Does anyone have operating procedures for centrifugal compressors?

.1.3 Put dry gas seal into use: 1.1.3.1 Use medium pressure nitrogen (pressure: 1.66MPa., normal temperature, flow rate: 300Nm3/h) as the air source of the primary sealing gas. The air source enters the sealing control system through the G1 flange port. After being filtered by the high-pressure fine filter F1 (or F2), one stream passes through the pneumatic membrane regulating valve PDV-2581 to adjust the pressure difference with reference to the secondary balance tube pressure PdICSA2581. Then it enters the primary sealing chamber at the low-pressure end and enters the shaft end seal through the flow orifice plate (Pdt2581). One flow passes through the flow orifice plate (FT2580, FT2581) and enters the primary sealing chamber of the high-pressure end. 1.1.3.2 Use low-pressure nitrogen at room temperature, 0.40MPa (G), and 120Nm3/h as the gas source for the secondary sealing gas and rear isolation gas. After entering the sealing control system through the G2 flange port, the gas source is finely filtered by filter F3 (or F4) and then divided into four channels to enter the high- and low-pressure end secondary sealing chambers and the rear labyrinth sealing chamber. 1.1.4 Contact the dispatching room to notify the circulating water position and make preparations before the circulating water is put into operation. 1.1.5 The switching status of ITCC and on-site inspection valves (except for instrument gas systems that have been put into operation and some normally open valves under shutdown conditions) are all closed. 1.1.6 Put the circulating water system into operation after receiving notification from the dispatching room. 1.1.6.1 Open the main valve for the circulating water in and out of the system. 1.1.6.2 Open the exhaust valve on the upper part of the inter-cylinder, inter-section cooler, condenser and oil-water cooler. When no gas is discharged from the exhaust valve, close it and open the inlet valve. 1.1.6.3 Open the condenser circulating water inlet valve, open the upper exhaust valve of the condenser, wait until no air is discharged from the upper exhaust valve, and when water flows out, close the exhaust valve, and open the condenser circulating water outlet valve. 1.1.7 Check that the oil level at the gas station is normal and that the oil temperature in the fuel tank is normal (if the oil temperature is low, the electric heater can be started in advance for heating). 1.1.8 Start the 1# oil pump of the oil station, open the oil filling valve to fill the high oil tank, and close it after it is full. Observe whether the oil pressure is normal. The primary oil pressure control is 1.1MPa (G). Check the oil return condition of the lubricating oil return main pipe, and control the pressure of the oil supply main pipe to 0.3MPa (G). 1.1.9 Check that all diversions in front of the main steam valve of the main steam pipeline are open. Adjust the valve to the appropriate opening according to the discharged steam and water. Open the bypass valve of the large steam valve, and open the diversion and drainage heating pipe on the pipeline after the bypass. 1.1.10 Contact the main dispatching department to supply desalted water for the turbine condenser. The emergency stop buttons of the two condensation water pump motors on site are turned on, and desalted water is added to the condenser. When the liquid level of the condenser reaches a high level and the alarm is triggered, water addition is stopped. Slowly open the inlet valve and outlet valve of the condensate pump. Open the cooling water inlet and outlet valves of the extractor cooler. 1.1.11 Condensate pump automatic start experiment: The emergency stop button of the 1# pump is reset, the 1# pump is started, and the 1# pump in the control room is turned on. The 2# pump is put into standby, the 2# pump motor emergency stop button is reset, the 2# pump starts automatically, and the dual pumps are running. In the same way, the 2# pump motor is running, the l# pump on-site emergency stop button, the 2# pump in the control room is put on the master, the 1# pump is put on the backup, the l# pump motor emergency stop button is reset, the 1# pump starts automatically, and the dual pumps are running. After the experiment is completed, turn on the pilot shower and drain until normal, then close the pilot shower, open the atmospheric safety valve water seal water filling valve, adjust the valve opening to ensure that no large amount of water flows out of the atmospheric safety valve exhaust port, stop the 2# pump in the control room, and select the 2# pump as a backup pump. 1.1.12 Double-pump interconnection test of oil pump: Check that the emergency stop button of the 2# backup oil pump is reset, the control system is switched to automatic, the 1# oil pump is switched to manual, the oil pressure regulating bypass valve is opened, if the oil pressure is lower than 0.15MPa, an alarm is given, and the 2# oil pump is started. Write down the data, close the oil pressure regulating bypass valve, and restore the oil pressure to normal. Stop the 1# pump and select the standby pump to start automatically, and the 2# pump to start manually. In the same way, do 1# automatic and 2# manual tests. 1.1.13 Low lubricating oil pressure trip test: 1.1.13.1 The control room checks whether the starting conditions of the turbine are met through the main interlocking diagram of the steam turbine. If the starting conditions are not met, it will be switched to bypass. 1.1.13.2 Notify the control room to press the "request interlock input (to DCS) button" for 2 seconds. When the interlock input signal appears in the ITCC, the ITCC operator sends power to the quick closing valve solenoid valve. In the control room, check that the solenoid valve light of the quick-closing valve is on and the solenoid valve is energized. 1.1.13.3 On site, turn the starting handle right to establish starting oil pressure. Turn the starting handle left to build up the quick-closing oil pressure and open the quick-closing valve. 1.1.13.4 Close the PCV2502 rear stop valve at the shared oil station and observe the lubricating oil pressure. When PS2512, PS2513, and PS2514 alarm, record the data (design value is 0.15MPaG). When the quick closing valve is closed, record the data (design value is 0.1 MPaG). 1.1.14 On-site gate opening and ITCC parking test: Establish the quick-closing oil pressure according to steps 1.1.13, open the quick-closing valve, press the parking handle on site, and close the quick-closing valve. At the same time, the quick-closing oil pressure is established and the quick-closing valve is opened. 1.1.15 Vacuum degree test: 1.1.15.1 Verify that the condensate pump is operating properly. 1.1.15.2 Open the valve on the condensate tank of the sealing gas regulating system and open the bypass valve of the regulating valve to artificially destroy the vacuum. According to the exhaust situation of the sealing gas discharge port, set the pressure to 0.0004~0.0006MPa and put it on automatically, and observe the tracking of the regulating valve until it stabilizes. 1.1.16 Contact the control room to start the turning device. The specific steps are: 1.1.16.1 Check that the emergency stop button of the turning device is reset. 1.1.16.2 Control room turning fault reset. 1.1.16.3 Observe that the turning preparation light is on. 1.1.16.4 Press the cranking device start button, the cranking device start light will light up, and the cranking device will run. 1.1.16.5 Open the extractor steam valve on site. 1.1.16.6 Open the steam extraction valve of the steam extractor and observe the vacuum degree on site. Observe the ITCC display vacuum degree, and when the alarm goes off, write down the data. 1.1.16.7 Stop the system and open the quick closing valve according to step (12). 1.1.16.8 Stop the steam extraction and slowly destroy the vacuum. The quick-closing valve operates to close. 1.1.16.9 Resume steam extraction and restore normal vacuum. 1.1.16.10 Adjust the water seal filling valve of the atmospheric safety valve on site to ensure that water flows out of the water seal overflow port. 1.1.17 Check that the ammonia compressor must meet the driving conditions 1.1.17.1 Check that the oil system, water system, and dry gas sealing system are in operating condition and that each valve is flexible and easy to use. 1.1.17.2 The control system meets the conditions for driving, and the monitoring of various instruments is normal and accurate. 1.1.17.3 Make preparations before starting the turbine. Prepare for drainage and pipe heating work. Steam is connected to the boundary area. 1.1.17.4 Open all pressure valves and put on-site instruments into use. 1.1.17.5 Open the second-way anti-surge valve of the compressor. 1.1.17.6 Close the ammonia inlet valve, the drain valve of the compressor gas-liquid separator, and the compressor outlet valve. 1.1.17.7 The ammonia compressor is qualified for nitrogen replacement. 1.2. Warming up (1000r.pm) 1.2.1 Open the main steam valve bypass valve, open the diversion valve in the factory building, and close it after draining water. 1.2.2 Notify the control room to stop turning and confirm on site. ITCC: Check the turbine starting interlock diagram to confirm that the starting conditions are met. 1.2.3 Check the steam drainage situation, observe the stability of the steam pressure and temperature in the entering section, confirm that the heating pipe is sufficient, contact the general dispatcher to confirm that the steam supply is guaranteed, press 5.1.1.12 Step 1: Open the quick-closing valve. 1.2.4 Inform the control room operator to press the start button on the governor panel. Press SPEED to switch to the conversion tracking interface and observe that the speed tracking on the panel is stable. 1.3 Increase the speed to 2000 rpm 1.3.1 Determine the speed increase time according to the time specified by the speed increase platform provided by Hangzhou Automobile (20 minutes) and the superheat of the steam (corresponding temperature under the corresponding pressure) (360℃ 2.5MPaA). 1.3.2 If the warm-up platform time has expired at 1000r.pm, but the temperature of the steam is not enough, you can stop the automatic speed increase, adjust the speed to 1000r.pm, and continue the low-speed warm-up. When the speed increase condition is reached, manually increase the speed to 2000r.pm. 1.3.3 If the warm-up platform time is sufficient, the speed can be automatically increased to 2000r.pm. 1.3.4 Observe the turbine shaft temperature displacement and vibration, observe the exhaust situation of the sealing gas exhaust port, and use sealing gas. 1.3.5 Observe the liquid level of the turbine condenser. If it is high, drain it appropriately. 1.3.6 Open the steam turbine cylinder guide shower. 1.3.7 Observe the cylinder temperature and main steam temperature and pressure (exhaust cylinder temperature

This post was last edited by 654262293 on 2010-8-10 11:33. The poster asked a question, centrifugal compressor? The scope can be narrowed down further. Is it an air compressor or a freezer? Or something else? The answer on the 2nd floor also doesn’t know why?

This post was last edited by 654262293 on 2010-8-10 11:32. The answer on the second floor is about the method of driving a centrifugal compressor driven by a steam turbine. It will be much simpler if it is driven by a motor. You can refer to the operation of centrifugal blower: 1. Preparation before driving: 1.1 Confirm that the oil level in the fuel tank is at 2/3 and the oil quality is good. 1.2 The temperature of the lubricating oil reaches above 35°C, otherwise the oil heater is turned on. 1.3 Manually turn the car for 2 to 3 turns to confirm that there are no abnormalities in the moving parts. During the cranking process, you should pay close attention to whether there are any abnormal sounds, abnormal collisions or jamming sounds, and whether the flow of lubricating oil is normal. When abnormal sounds or looseness are found, you should stop cranking immediately and check and handle to eliminate faults or abnormal conditions. 1.4 Open the oil cooler inlet and outlet valve. 1.5 Cooperate with instruments and electrical to check whether each control measuring instrument and the self-protection interlocking system are normal. 1.6 Check whether the process pipelines and ancillary pipelines are intact. 1.7 Contact the mechanical, electrical and instrument personnel to be present. 1.8 Contact an electrician to send electricity. 1.9 Turn on the auxiliary oil pump and check whether the oil pressure is normal. 2. Starting conditions: 2.1 The lubricating oil pressure is normally above 0.09MPa. 2.2 Open the fan inlet valve slightly, about 7-15°. 2.3 The anti-surge valve at the fan outlet is fully open. 2.4 The normal temperature of lubricating oil is between 35~45℃. 3. drive a car: 3.1 After confirming that the driving conditions are met, turn on the main motor. 3.2 Start the main oil pump together with the main engine, confirm that the pressure parameters of the lubricating oil system are normal, switch the auxiliary oil pump from manual to automatic within 1 minute, and stop the auxiliary oil pump. 3.3 Adjust the cooling water amount according to the lubricating oil temperature. When the lubricating oil temperature shows 40°C, open the water in the circulating cooler, and adjust the cooling water circulation amount through the inlet valve to keep the lubricating oil temperature between 35 and 45°C. At this time, completely open the cooling water outlet valve. 3.4 After confirming that the fan is running normally at low load, contact the main control room to prepare to supply air to the system, and slowly adjust the fan inlet valve to make the fan outlet pressure meet the process operation requirements. ； Slowly open the outlet inlet system valve until it is fully open, and slowly close the anti-surge vent valve.

Section 1 Overview 1. Application of Centrifugal Compressor The centrifugal compressor is a blade rotary compressor (i.e. turbine compressor). In a centrifugal compressor, the high-speed rotating impeller gives the gas a centrifugal force and a diffusion channel to the gas, thereby increasing the gas pressure. In the early days, because this kind of compressor was only suitable for low and medium pressure and large flow situations, it was not noticed by people. But recently, due to the development of the chemical industry and the establishment of various large-scale chemical plants and refineries, centrifugal compressors have become a key machine for compressing and transporting various gases in chemical production, and occupy an extremely important position. With the achievements of gas dynamics research, the efficiency of centrifugal compressors has been continuously improved, and due to the successful development of key technologies such as high-pressure sealing, processing of small-flow narrow impellers, and multi-oil wedge bearings, a series of problems in the development of centrifugal compressors towards high pressure and wide flow ranges have been solved. The application range of centrifugal compressors has been greatly expanded, so that it can replace reciprocating compressors in many occasions. * * greatly expanded the scope of application. The pressure of industrial high-pressure centrifugal compressors ranges from (150~350)×105Pa, and the pressure of centrifugal compressors used for gas injection in offshore oil fields ranges as high as 700×105Pa. The centrifugal blower used for blast furnace blast has a flow rate as high as 7000m3/min, a power of 52900KW, and a rotation speed generally above 10000r/min. Some basic chemical raw materials, such as propylene, ethylene, butadiene, benzene, etc., can be processed into important chemical products such as plastics, fibers, and rubber. In petrochemical plants that produce this basic raw material, centrifugal compressors also play an important role and are one of the key pieces of equipment. In addition, centrifugal compressors are also extremely critical equipment in other industries such as petroleum refining and refrigeration. The reason why centrifugal compressors are so widely used is that they have the following advantages over piston compressors. 1. The centrifugal compressor has large gas capacity, compact structure, light weight, small unit size and small floor space. 2. It has balanced operation, reliable operation, high operating rate and few friction parts, so it requires less spare parts, less maintenance costs and less personnel. 3. In the chemical process, the centrifugal compressor can achieve an absolutely oil-free compression process for chemical media. 4. The centrifugal compressor is a rotary motion machine, which is suitable for direct driving of industrial steam turbines or gas turbines. For general large-scale chemical plants, by-product steam is often used to drive industrial steam turbines as power, which provides the possibility for comprehensive utilization of heat energy. However, centrifugal compressors also have some disadvantages. 1. Centrifugal compressors are currently not suitable for situations where the gas volume is too small and the pressure ratio is too high. 2. The stable operating range of the centrifugal compressor is narrow, and although its gas volume adjustment is more convenient, it is less economical. 3. At present, the efficiency of centrifugal compressors is generally lower than that of piston compressors. my country has been able to manufacture centrifugal compressors in the 1950s. Since the early 1970s, it has introduced a series of high-performance medium and high-pressure centrifugal compressors, mainly in petrochemical plants and large fertilizer plants. It has gained rich experience in use and has digested and absorbed the imported technology. * * Enhanced its own research, design and manufacturing capabilities. 2. Types of centrifugal compressors There are many types of centrifugal compressors, which can be classified according to the following aspects according to their performance and structural characteristics. Classification name description According to the exhaust pressure, the exhaust pressure of low-pressure compressor is 3~10Kg/cm2, the exhaust pressure of medium-pressure compressor is 10~100Kg/cm2, the exhaust pressure of high-pressure compressor is 100~1000Kg/cm2, the exhaust pressure of ultra-high pressure compressor is >1000Kg/cm2, according to the power, the shaft power of micro compressor is less than 10KW and the shaft power of small compressor is 10~100KW. The shaft power of medium-sized compressors is 100~1000KW. The shaft power of large-scale compressors is above 1000KW. According to the flow rate of the suction gas, the flow rate of small-flow compressors is less than 100Nm3/min. The flow rate of medium-flow compressors is 100~1000Nm3/min. The flow rate of large-flow compressors is greater than 1000Nm3/min. According to the structural characteristics, it is divided into horizontal split type and vertical split type. Section 2: Working principle and structure of centrifugal compressor 1. Working principle The steam turbine (or electric motor) drives the main shaft impeller of the compressor to rotate. Under the action of centrifugal force, the gas is thrown into the diffuser behind the working wheel. A thin zone is formed in the middle of the working wheel, and the gas in front enters the impeller from the steam inlet part in the middle of the working wheel. Due to the continuous rotation of the working wheel, the gas can be continuously thrown out, thus maintaining the continuous flow of gas in the air compressor. The pressure of the gas increases due to centrifugal action, and it can also leave the working wheel at a very high speed. The gas gradually reduces its speed through the diffuser, and the kinetic energy is converted into static pressure energy, further increasing the pressure. If the pressure obtained by one working impeller is not enough, multi-stage impellers can be connected in series to meet the outlet pressure requirements. The series connection between stages is realized through bends and refluxers. This is how a centrifugal compressor works. 2. Basic structure The centrifugal compressor is composed of two parts: the rotor and the stator. The structure is shown in Figure 6-1. The rotor includes a rotating shaft, an impeller, a shaft sleeve, a balance plate, a thrust plate, a coupling and other components fixed on the shaft. The stator has a cylinder, various partitions positioned on the cylinder, and bearings and other components. Sealing elements are also provided where gas sealing is required between the rotor and stator. The functions of each component are introduced below. 1. Impeller The impeller is the most important component in a centrifugal compressor. The mechanical work of the driver is the work done by the high-speed rotating impeller on the gas to obtain energy from the gas. It is the only power-operating component in the compressor, also known as the working wheel. The impeller is generally a closed impeller composed of a wheel cover, a disc and blades, and there are also semi-open impellers without a wheel cover. 2. Spindle The spindle plays the role of supporting rotating parts and transmitting torque. According to its structural form. There are two types: stepped shaft and optical shaft. The optical shaft has the characteristics of simple shape and convenient processing. 3. In a multi-stage centrifugal compressor, the balance plate has different gas forces on both sides of each stage impeller, so the rotor is subject to a resultant force directed toward the low-pressure end. This resultant force is called the axial force. Axial force is harmful to the normal operation of the compressor. It can easily cause damage to the thrust bearing, causing the rotor to move to one end, causing the moving parts to shift and lose the correct relative position between the fixed components. In serious cases, the rotor may collide with fixed components and cause an accident. The balance plate is a part that uses the gas pressure difference on both sides to balance the axial force. The pressure on one side is the pressure in the gap on the side of the final impeller disk, and the other side leads to the atmosphere or the air inlet pipe. Usually the balance plate only balances a part of the axial force, and the remaining axial force is borne by the thrust bearing. An air seal needs to be installed on the outer edge of the balance plate to prevent gas from leaking and maintain the differential pressure on both sides. The balance of axial force can also be balanced by the air intake on both sides of the impeller and the reverse installation of the impeller. 4. Thrust plate: Since the balance plate only balances part of the axial force, the rest of the axial force is transmitted to the thrust block on the thrust bearing through the thrust plate, forming a balance of forces. The contact surface between the thrust plate and the thrust block should be made very smooth, and the gap between the two should be filled with suitable lubricating oil. Under normal operation, the thrust block will not wear. When the centrifugal compressor starts, the rotor It will move to the other end. In order to ensure the normal position of the rotor, the rotor needs to be thrust on both sides. The reason is that when the compressor is started, the gas at all levels has not yet been established, and the pressure difference on both sides of the balance plate does not yet exist. As long as the gas flows, the rotor will move in the opposite direction to the normal axial force. Therefore, the rotor is required to be thrust on both sides to prevent accidents. 5. Coupling Since the centrifugal compressor has the characteristics of high-speed rotation, high power and inevitable vibration during operation, the coupling used must be able to transmit large torque and allow a small amount of radial and axial displacement. The coupling is divided into tooth type coupling and diaphragm coupling. Currently, diaphragm couplings are commonly used. This coupling does not require lubricant and is easy to manufacture. 6. Casing: The casing is also called a cylinder. For medium and low-pressure centrifugal compressors, a horizontally divided casing is generally used to facilitate assembly. The upper and lower casings are positioned by positioning pins, that is, connected with bolts. For high-pressure centrifugal compressors, a cylindrical forged steel casing is used to withstand high pressure. The end cover of this structure is connected to the cylindrical casing with bolts. 7. When the diffuser gas flows out of the impeller, it still has a high flow speed. In order to make full use of this part of the velocity energy to increase the pressure of the gas, a diffuser with a gradually expanding flow area is installed behind the impeller. Diffusers generally come in various forms, including bladeless and straight-wall diffusers. 8. The curve is between the intermediate stage and the stage of the multi-stage centrifugal compressor. The gas must turn, so the curve is used. The curve is a curved annular space composed of the casing and the partition. 9. The channel connected behind the bend is the recirculator. The function of the recirculator is to make the air flow evenly enter the next stage in the required direction. It is composed of partitions and guide vanes. The guide vanes are usually arc-shaped and can be cast integrally with the cylinder or manufactured separately and then connected together with bolts. 10. Volute The main purpose of the volute is to collect the gas flowing out after the diffuser or the impeller and lead it out of the machine. The cross-sectional shapes of the volute include circular, plow, trapezoid and rectangular. 11. Seal In order to reduce the amount of air leakage through the gap between the rotor and the fixed components, seals are often installed. There are two types of sealing: inner sealing and outer sealing. The function of the inner seal is to prevent gas from flowing back between stages, such as the wheel cover seal at the wheel cover and the separator seal between the separator and the rotor. The external seal is set up to reduce and prevent the gas inside the machine from leaking out, or the outside air from escaping into the machine, such as the seal at the machine end. There are many types of seals in centrifugal compressors, the following are commonly used: 1) Labyrinth seal Labyrinth seal is currently a more commonly used sealing device for centrifugal compressors, used for the outer seal and inner seal of the compressor. Gas flow in labyrinth seal (see Figure 6-2) , when the gas flows through the gap of the comb-shaped labyrinth sealing plate, the gas undergoes an expansion process, and the pressure drops from P1 to P2 on the right end. This expansion process is completed gradually. When the gas enters the sealing chamber from the gap of the sealing plate, due to the sudden expansion of the cross-sectional area, the airflow forms a strong vortex, causing the velocity to almost completely disappear. There is a pressure difference between the gas on both sides of the sealing surface. The pressure in the sealing chamber is the same as the pressure at the gap. According to the law of gas expansion, as the gas pressure decreases, the velocity should increase and the temperature should drop, but because the flow of gas in a narrow gap is of a throttling nature, the kinetic energy of the gas due to the pressure drop is completely lost in the sealed cavity and converted into useless heat energy. This part of the heat energy is turned around and heats the gas, so that the temperature that has just dropped with the pressure rises again and returns to the temperature when the pressure has not dropped. The air flow passes through each subsequent sealing piece and cavity and repeats the above process until the pressure P2. It can be seen that the labyrinth seal uses the throttling principle. Every time the gas passes through a tooth plate, the pressure will drop. After passing through a certain number of tooth plates, there will be a larger pressure drop. In essence, the labyrinth seal provides pressure difference resistance to the flow of gas, thereby reducing the passage of gas. The most commonly used labyrinth seals are as follows. The smooth shape is shown in Figure 6-3. The shaft is made into a smooth axis. The sealing body is machined with comb teeth or inlaid with tooth plates. The structure is simple. Figure 6-3 Smooth labyrinth seal The zigzag shape is shown in Figure 6-4. In order to increase the throttling and pressure reducing effect of each tooth plate, the zigzag labyrinth seal was developed, and the sealing effect is better than that of the smooth labyrinth seal. Figure 6-4 The zigzag labyrinth seal step shape is shown in Figure 6-5. The sealing effect of this type is also better than that of the smooth type. It is often used for sealing the impeller cover and generally has 3 to 5 sealing teeth. 2) Oil film seal, that is, floating ring seal. The principle of floating ring seal is to rely on the high-pressure seal to form a film between the floating ring and the shaft sleeve, which produces throttling and pressure reduction, preventing the high-pressure side gas from flowing to the low-pressure side. The floating ring seal can form an oil film in the gap between the ring and the shaft, and the ring itself can freely float radially. The ring on the high-pressure side is called a high-pressure ring, and the ring on the low-pressure side is called a low-pressure ring. These rings can float freely in the radial direction, but cannot rotate. The sealing oil pressure is usually about 0.5Kg/cm2 higher than the process gas pressure. It enters the sealing chamber and flows to the high-pressure side through the gap between the high-pressure ring and the shaft. An oil film is formed in the gap to seal the high-pressure gas. The other way flows out from the gap between the low-pressure ring and the shaft and returns to the tank. Usually there are several low-pressure rings to achieve the purpose of sealing. The floating ring seal is made of steel, and the end face is tin-plated bronze. The inner side of the ring is poured with babbitt alloy to prevent short-term contact between the shaft and the oil ring. The babbitt alloy is used as a wear-resistant material. Floating ring seals can be completely leak-proof and are widely used as shaft sealing devices for compressors. 3) Mechanical seal Mechanical seal device is sometimes used on the shaft seal of small compressors. The main differences between mechanical seals for compressors and mechanical seals for general pumps are high rotation speed, high linear speed, high PV value, high friction heat and high dynamic balance requirements. Therefore, the spring and its loading device are generally designed to be static in structure and the geometry of the rotating parts should be symmetrical. The transmission method does not use pins, chains, etc., to reduce the influence of centrifugal force caused by unbalanced mass. At the same time, from the perspective of friction parts and end face specific pressure, a double-end face partial balance type should be adopted as much as possible. The end face width should be small and the friction coefficient of the friction pair material is low. At the same time, cooling and lubrication should be strengthened to quickly dissipate the friction heat of the sealing surface. 4) Dry gas seal With the continuous improvement and development of fluid dynamic pressure mechanical seal technology, one of its important sealing types, spiral groove surface gas dynamic pressure seal, namely dry gas seal, has been widely used in the petrochemical industry. Dry gas seals have many advantages over oil seals and floating ring seals.: Stable, reliable and easy to operate, with few auxiliary systems. * * The maintenance workload of the operator is reduced, and the seal consumes only a small amount of nitrogen, which is both energy-saving and environmentally friendly. Figure 6-6 shows a schematic diagram of a spiral groove surface dry gas seal. It consists of a moving ring 1, a static ring 2, a spring 4, O-rings 3, 5, 8, an assembly sleeve 7 and a shaft 6. Figure 6-7 shows the sealing surface where thread grooves are finished on the surface of the moving ring and then ground and polished. Generally speaking, the depth of the spiral groove is about 2.5~10μm. The parallelism of the sealing ring surface is very demanding, which needs to be less than 1μm. The shape of the spiral groove is approximate to a logarithmic spiral. As shown in Figure 6-7, when the moving ring rotates, the nitrogen used for sealing is sucked into the spiral groove circumferentially, flowing from the outer diameter toward the center and radially toward the sealing weir. The sealing weir plays a role in blocking the flow of gas to the center, so the gas is compressed and causes a pressure increase. The pressure of this gas film layer attempts to push open the seal and form the required gas film. The typical value of this balance gap or film thickness h is 3μm. In this way, the pressure of the sealed gas and the spring force are well matched with the pressure of the gas film layer, so that the gas film has good elasticity and high stiffness of the gas film, forming stable operation and preventing the sealing surfaces from contacting each other. At the same time, the nitrogen film with good stiffness can effectively prevent the leakage of the medium. The force of the dry gas seal is shown in Figure 6-8. Under normal operating conditions, the closing force (spring and gas force) of the seal is equal to the opening force (gas film force). When disturbed by external forces and the gap decreases, the gas shear rate increases, and the efficiency of the spiral groove in opening the gap increases. The opening force is greater than the closing force and returns to the original gap. If the gap is increased by external interference, the membrane pressure in the gap decreases, the opening force is less than the closing force, and the sealing surface closes and returns to the original gap. 12. Bearings Centrifugal compressors have radial bearings and thrust bearings. The radial bearing is a sliding bearing. Its function is to support the rotor and make it run at high speed. The thrust bearing bears the remaining axial force on the rotor, limits the axial movement of the rotor, and maintains the axial position of the rotor in the cylinder. (1) Radial bearings Radial bearings mainly consist of bearing seats, bearing caps, upper and lower half bearings, etc. Bearing seat: It is used to place the bearing bush. It can be cast together with the cylinder, or it can be cast separately and supported on the machine base. The force exerted by the rotor on the bearing will eventually be transmitted directly or indirectly to the machine base and foundation through it. Bearing cap: Cover the bearing bush and maintain a certain tightness with the bearing bush to prevent the bearing from beating. The bearing cover is fastened to the bearing seat with bolts. bush: It is used to directly support the journal, and the round surface of the bearing bush is poured with babbitt alloy. Because of its good friction reduction, high plasticity, and easy pouring and running-in, it is widely used in centrifugal compressors. In practice, for the convenience of loading and unloading, the bearing bush is usually made into upper and lower halves and fastened with bolts. The thickness of babbitt alloy currently used is usually 1~2mm. There are two ways to place the bearing bush in the bearing seat:: One is that the bearing bush is fixed, and the other is movable, that is, there is a spherical surface on the back of the bearing bush, which can automatically adjust the position of the bearing bush as the spindle deflection changes during movement, so that the bearing bush is stressed evenly along the entire length. The lubricating oil enters the bearing from the oil hole on the side surface of the bearing. On the oil path entering the bearing, a throttle orifice plate is installed. With the change of the diameter of the throttle orifice plate, the amount of oil entering the bearing can be adjusted. There is an annular oil groove in the upper half of the bearing bush, so that the lubricating oil can circulate better and cool the journal. (2) Thrust bearings, like radial bearings, thrust bearings are also divided into upper and lower halves. There are positioning pins on the middle plane and are connected with bolts. A positioning sleeve is used between the spherical shell and the spherical seat to prevent relative rotation. Because it is a spherical support, it can be automatically adjusted according to the degree of shaft deflection. The thrust bearing and the thrust plate work together. The thrust plate installed on the shaft rotates with the shaft, pressing the thrust from the shaft on several stationary thrust blocks. A layer of Babbitt alloy is also cast on the working surface of the thrust block. The thickness error of the thrust block is less than 0.01~0.02mm. Mitchell thrust bearings and Kingsbury thrust bearings are widely used in centrifugal compressors. During normal operation of a centrifugal compressor, the axial force always points to the low-pressure end, and the thrust block that bears this axial force is called the main thrust block. When the compressor starts, since the direction of the momentum of the airflow points to the high-pressure end, this force causes the axial high-pressure end to move. In order to prevent the axial high-pressure end from moving, another thrust block is installed. This thrust block is opposite the main thrust block and is called an auxiliary thrust block. There is a certain gap between the thrust plate and the thrust block to facilitate the formation of oil film. This gap is generally within 0.25~0.35mm. The most important thing is that the maximum value of the gap should be less than the minimum axial gap between the fixed component and the rotating component, so as to avoid collision between moving and static parts. The lubricating oil enters the spherical housing from the oil inlet at the lower part of the spherical surface, and then divides into two paths. One path enters the radial bearing through the middle splitting surface, and the other path leads to the thrust bearing through two sets of inclined holes. Part of the oil entering the thrust bearing enters the main thrust block, and the other part enters the auxiliary thrust block. Section 3 Adjustment of Centrifugal Compressor The operating operating points of the centrifugal compressor are shown on its characteristic curve, and the pressure and flow are in one-to-one correspondence. However, at which operating point the compressor will operate stably must be determined jointly with the compressor's pipe network system. The compressor has a certain stable operating point under a certain pipeline network state, and when the pipeline network state changes, the compressor's operating conditions will also change accordingly. 1. Pipe network characteristic curve The so-called pipe network generally refers to the general name of the intake pipeline, exhaust pipeline, and accessories and equipment on these pipelines connected to the compressor. But for centrifugal compressors, the pipe network only refers to the pipelines and all devices behind the compressor. Because after this provision, when studying the relationship between the compressor and its pipe network, the problem that the air inlet conditions of the compressor will change with the working conditions can be avoided, which simplifies the problem. Figure 5-6-8 shows the schematic diagram of the compressor connected to the first device in the exhaust system. There is an adjustment valve on the exhaust pipe. In order to send gas into the equipment with internal pressure Pr, the pressure at the beginning of the pipe network (called the back pressure at the compressor outlet) Pe is: Pe=Pr＋△P=Pr＋AQ2 (1) In the formula, △P includes friction loss and local resistance loss in the pipe network, and A is the calculation coefficient of the total resistance loss. Q Figure 6-9 Pipe Network Performance Curve Expressing equation (1) in Figure 6-9 is a quadratic curve. It is the relationship between the pipe network end pressure and the air intake volume, and is called the pipe network performance curve. The performance curve of the pipe network is actually equivalent to the resistance curve of the pipe network. The shape of this curve is related to the pressure of the container and the resistance of the pipeline. When the pipe network from the compressor to the container is very short and the valve is fully open, so the resistance loss is very small, the pipe network characteristic curve is almost a horizontal line such as line 1. When the pipeline is very long or the valve is closed, the resistance loss increases and the slope of the pipe network performance curve increases, thus becoming line 2. The smaller the valve opening, the steeper the curve becomes, such as line 3. If the pressure in the vessel decreases, the network performance curve will shift downward ； When Pr is normal pressure, the performance curve of the pipe network is line 4. It can be seen that the performance curve of the pipe network changes with the pressure and resistance of the pipe network. 2. Working point of the centrifugal compressor When the centrifugal compressor delivers gas to the pipe network, if the gas flow and discharge pressure are quite stable (that is, the fluctuation is very small), this means that the performance of the compressor and the pipe network is coordinated and in a stable operating state. This stable operating point has two conditions: First, the exhaust volume of the compressor is equal to the air intake volume of the pipe network ； Second, the discharge pressure provided by the compressor is equal to the end pressure required by the pipe network. Therefore, this stable operating point must be the intersection point of the compressor performance curve and the pipe network performance curve, because this intersection point meets the above two relevant conditions. For the convenience of explanation, the volume flow rate is converted into mass flow rate G. Line 1 in Figure 6-10 is the compressor performance curve, line 2 is the pipe network performance curve, and the intersection of the two is point A. Assume that the compressor is not working at point A but at a certain point A1. Since in this case, the flow rate G1 of the compressor is greater than the G0 at point A. When the flow rate is G1, the pipe network requires the end pressure to be PB1, which is greater than the pressure PA1 that the compressor can provide. At this time, the compressor can only automatically reduce the volume (reduce the kinetic energy of the gas to make up for the lack of pressure energy) ； As the air volume decreases, its exhaust pressure gradually increases until it returns to the operating point A. Assume that instead of returning to operating point A, we reach operating point A2. At this time, the exhaust pressure provided by the compressor is greater than the pressure required by the pipe network. The compressor flow will automatically increase, and the exhaust pressure will decrease accordingly. It will not be stable until it is equal to the pipe network pressure. This proves that only the intersection point A of the two curves is the stable operating point of the compressor. Figure 6-10 Stable operating condition point of centrifugal compressor 3. Maximum flow condition and surge condition 1. Maximum flow condition The operating condition when the compressor flow reaches the maximum is the maximum flow condition. There are two possibilities for causing this situation:: First, the air flow at a certain throat in the middle stage reaches a critical state. At this time, the volumetric flow rate of the gas is already at its maximum value. No matter how much the back pressure of the compressor decreases, the flow rate cannot increase further. This situation is called a "blocking" condition. Another situation is that the flow channel has not reached a critical state, that is, a "blocked" working condition has not yet occurred, but the compressor has a large flow loss in the machine at a huge flow rate, and the exhaust pressure it can provide is very small, almost close to zero energy head. It is only enough to overcome the flow resistance of the exhaust pipe to maintain such a large flow rate. This is also the maximum flow rate condition of the compressor. 2. Surge working condition: The working condition of the centrifugal compressor at the minimum flow rate is the surge working condition. As shown in Figure 6-10, line 1 is the hump-shaped centrifugal compressor PG characteristic curve, and point A3 is the peak point. When the flow rate of the centrifugal air compressor is reduced to make the air compressor work at point A3 of the characteristic curve, if the flow rate of the compressor further decreases for some reason, the outlet pressure of the air compressor will drop. However, the volume of the pipeline and system is large, and the gas is compressible, so the pressure in the pipe network cannot drop immediately and is still greater than the discharge pressure of the compressor, and gas will flow back into the machine. The air compressor supplements the flow rate and increases the outlet pressure. When the outlet pressure is higher than the pipe network pressure, the gas is discharged into the system again. In this way, when the air compressor works to the left of point A3, the gas will flow and oscillate repeatedly in the machine, causing strong fluctuations in flow rate and outlet pressure, which is the so-called surge phenomenon. When the compressor surges, the discharge pressure pulsates greatly, the gas flows in and out, periodic roars and strong vibrations of the machine occur. If timely measures are not taken to solve the problem, the bearings and seals of the compressor will be damaged first. In severe cases, the rotor and fixed components may even rub against each other, causing a vicious accident. The working condition corresponding to point A3 is the minimum flow condition of the compressor. The reason for surge is that the flow rate of the compressor is too small, less than the minimum flow rate of the compressor, and the pressure of the pipe network is higher than the discharge pressure provided by the compressor, causing gas to flow back and produce large air flow pulsations. The principle of anti-surge is to target the cause of surge and immediately try to increase the flow rate of the compressor when surge is about to occur. 3. Analysis of surge examples: When the performance curve of the compressor and the performance curve of the pipe network, or one of the two, changes, the intersection point will change, which means that the working conditions of the compressor will change, resulting in variable working condition operations. The characteristic curve (ε-Q) of the centrifugal compressor is related to the rotation speed of the compressor, the properties of the medium and the air intake state. The changes in the performance curve are shown in Figure 5-6-11. Figure 6-11 Changes in performance curves The changing operating conditions of centrifugal compressors sometimes do not occur under people's conscious direct control (such as adjusting valves, etc.), but indirectly occur due to unexpected interference from the production system or even the driver. Unexpected surges often occur in chemical plant centrifugal compressors. Examples are as follows. Figure 6-12 Surge caused by changes in centrifugal compressor performance a. The original inlet air temperature of a compressor was 20°C and the operating point was at point A (see Figure 6-12a). Due to a failure of the cooler during production, the incoming air temperature increased sharply to 60°C. At this time, the compressor suddenly surged. The reason is that the increase in inlet air temperature causes the compressor performance curve to shift downward, from line 1 to 1', while the pipe network performance curve does not change, and the compressor's working point changes to point A'. If this point falls on the surge limit, surge will occur. b. A certain compressor was operating normally at point A shown in Figure 6-12b. Later, for some reason, the air inlet pipe was blocked by foreign matter and surge occurred. The reason is analyzed that the air inlet pipe is blocked, the compressor inlet pressure drops from Pj to Pj', causing the machine performance curve to drop to the 1' line, and the pipe network performance curve does not change, so the operating point changes to A', falling into the surge limit. c. A certain compressor originally operated normally at a speed of n1, and the operating point was point A (see Figure 6-12C). Later, due to insufficient supply of high-pressure steam during production, the speed of the steam turbine as the driving engine dropped to n2. At this time, the working point A' of the compressor fell into the surge zone, thus causing surge. In addition, there are cases of surge caused by changes in gas molecular weight. The above situations all cause surge due to the downward shift of the compressor performance curve, and the performance of the pipe network has not changed. Sometimes surge is caused by changes in the performance curve of the pipe network (for example, the curve shifts upward or becomes steeper). Figure 6-13 Surge caused by changes in pipe network performance. A compressor was originally working at point A' (see Figure 6-13). Later, due to instability in the production system, the pressure in the pipe network increased significantly, and the pipe network performance curve moved up from 2 to line 2' (the performance curve of the compressor did not change at this time), so the compressor surged. Another similar situation is that when the exhaust pipe valve is closed too small, the pipe network performance curve becomes steeper. Once the working point of the compressor falls into the surge zone, surge occurs suddenly. When the performance of both the compressor and the pipe network changes for some reason, surge will suddenly occur as long as the final result is that the intersection point of the two curves falls within the surge zone. For example, during the startup process (speed increase and pressure increase) and shutdown process (speed reduction and pressure reduction) of a centrifugal compressor, both performance curves are gradually changing. Changing the speed is changing the compressor performance curve, and increasing or reducing the pressure in the system is changing the pipe network performance curve. During operation, you must always pay attention to the coordinated changes of the two to ensure that the compressor always works in the stable working condition area. 4. Adjusting the operating conditions of centrifugal compressors The essence of compressor adjustment is to change the operating point of the compressor. In principle, the method used is to try to change the performance curve of the compressor or change the performance curve of the pipe network. Specifically, there are the following adjustment methods:: a. Outlet throttling adjustment, that is, installing a regulating valve at the compressor outlet, and adjusting the opening of the regulating valve to change the pipeline performance curve, change the working point of the compressor, and adjust the flow rate. The adjustment method of outlet throttling is to artificially increase the outlet resistance to adjust the flow rate, which is an uneconomical method. Especially when the compressor performance curve is steep and the adjusted flow rate (or pressure) is large, the shortcomings of this adjustment method are more prominent. Currently, except for fans and small blowers, compressors rarely use this adjustment method. b. Inlet throttling adjustment, which means installing a regulating valve on the compressor inlet pipe and adjusting the inlet pressure through the inlet regulating valve. The reduction in air inlet pressure directly affects the compressor exhaust pressure and shifts the compressor performance curve downward. Therefore, the result of inlet adjustment is actually to change the compressor performance curve to achieve the purpose of adjusting the flow rate. Compared with the outlet throttling method, the inlet throttling adjustment is more economical. According to relevant information, a test on a certain compressor showed that: Within the flow range of 60 to 80%, inlet throttling saves about 4 to 5% more power than outlet throttling. So this is a relatively simple and commonly used adjustment method. However, there is still a certain throttling loss and some impact on the efficiency of the compressor itself after changes in working conditions. Another advantage of the import throttling method is that: Closing the inlet valve will move the compressor performance curve to the small flow area, thus allowing the compressor to work under smaller flow conditions and less likely to cause surge. c. Change the speed adjustment. When the compressor speed changes, its performance curve also changes accordingly, so this method can be used to change the operating point to meet production adjustment requirements. The energy head of the centrifugal compressor is approximately proportional to n2, so a considerable adjustment range can be obtained using the speed adjustment method. Variable speed adjustment does not cause other additional losses, but the new operating point after adjustment is not necessarily the highest efficiency point, resulting in some reduction in efficiency. Therefore, from the perspective of energy saving, this is an economical adjustment method. Changing the speed adjustment method does not require changing the structure of the compressor itself, but only needs to consider issues such as the strength of the rotor, critical speed and bearing life after increasing the speed. However, this method requires that the driver must be speed-adjustable. Section 4 Start-up and Stop of the Centrifugal Compressor Unit 1. Preparation and inspection before operation of the compressor unit 1. The driver and gear transmission should be tested individually and in series, and should be inspected and accepted to reach a complete standby state. Install the couplings between the driver, gear transmission and compressor, and recheck the alignment between the rotors to make them fully meet the requirements. 2. The unit's oil system has been properly cleaned and adjusted, the oil quality test meets the requirements, and the oil storage capacity is moderate. Check the main oil tank, oil filter, and oil cooler. If the oil level in the oil tank is insufficient, add more oil. Check that if the oil temperature is lower than 24°C, a heater should be used to make the oil temperature reach above 24°C. The oil cooler and oil filter should also be filled with oil and air should be released. The switching position of the oil cooler and filter should be switched to the side that needs to be put into use. Check the main oil pump and auxiliary oil pump to make sure they are working properly and steering correctly. The oil thermometer and pressure gauge should be complete, with qualified range and working properly. Fill the accumulator with dry nitrogen to keep the gas pressure in the accumulator within the specified value. Adjust the oil pressure in various parts of the oil system to meet the design requirements. Check the normal operation of various interlocking devices in the oil system to ensure the safety of the unit. 3. Each inlet filter of the compressor should be clean and undamaged, the inlet filter elements have been replaced, and the filter is qualified. 4. The compressor cylinder and pipeline drain valves have been opened. Turn them down after draining the condensation, and close them after inflating. 5. The intercoolers of each section of the compressor introduce water to establish cooling water circulation, exhaust the air and put it into operation. 6. The process piping system should be in good condition, the blind plates have all been removed and reset, and the weight of the cylinder body is not allowed to be affected by the expansion, contraction and vibration of the pipeline. 7. Adjust the valves on the process gas pipeline to a certain position according to the starting requirements. Generally, the inlet and outlet valves of the compressor should be closed, the anti-surge return valve or vent valve should be fully open, and the outlet valve to the process system should also be fully closed. The switches of various valves should be flexible and accurate without jamming. 8. Confirm that the safety valves and explosion-proof panels on the compressor pipeline and ancillary equipment are fully equipped, the safety valves are adjusted and adjusted to meet the requirements, and the specifications of the explosion-proof panels meet the requirements. 9. The instruments on the compressor and its auxiliary machinery are fully installed, and the range, temperature, pressure and accuracy level all meet the requirements. Important instruments should have calibration certificates. Check the electrical wiring and instrument air system for integrity. Instrument valves should be flexible and accurate, and the automatic control security system should be inspected and qualified to ensure accurate actions. 10. All interlocks of the unit have been tested and adjusted, and all setting values ​​have met the requirements. The anti-surge protection control system has passed the calibration test. Each vent valve and anti-surge return valve should open and close quickly without jamming. 11. Based on analysis, confirm that the gas composition in the process system before and after the compressor enters and exits the valve has met the design requirements or has been replaced with nitrogen. 12. Turn the machine to check whether the rotor of the unit can rotate smoothly and there should be no friction or jamming. 2. Start-up and shutdown of the steam turbine drive unit The system structure of the steam turbine-driven centrifugal compressor unit is relatively complex. The steam turbine is a thermal machine that operates at high temperature and high speed. Its start-up, stop, and operation are relatively complex and slow. After the installation and maintenance of the unit, a trial operation is also required. According to the provisions of professional regulations, the steam turbine unit must first be trial-operated, and necessary adjustments and tests must be performed. After passing the inspection, it will be connected to the gear transmission for series no-load operation. Only after completing the trial operation project and passing the acceptance check can it be connected in series with the compressor for trial operation and normal start-up and shutdown operation. The key points for the start-up and shutdown operation of this type of unit are as follows. 1. Starting of the oil system The starting of the compressor is similar to that of other power devices. The main engine is turned on last and the auxiliary engine is started first. After connecting various external energy sources (such as electricity, instrument air, cooling water and steam, etc.), the oil system is put into operation first. —The oil system is generally fully prepared and ready to start driving at any time. If the oil temperature is low, it should be heated until it is qualified. After the oil system is put into operation, adjust the oil pressure of each part to the specified value, and then perform the following operations: Check the automatic starting of the auxiliary oil pump ； Check the oil return condition of the bearing to see if the oil flow is normal ； Check the oil pressure drop in the oil filter and fill the lubricating oil tank ； Check the oil level in the high-level oil tank. It should be between the highest level and the lowest level controlled by the level controller. 2. Gas replacement When the compressed medium is flammable or explosive gas, after the oil system is in normal operation, gas replacement must be performed before starting the vehicle. First, use nitrogen to replace the air in the compressor system equipment pipeline. Then use compressed medium to completely replace the nitrogen so that it meets the gas composition required by the design. The main procedure of this two-step replacement is: ①Close the compressor inlet and outlet valves, and charge nitrogen with a pressure of generally 0.3 to 0.6MPa (meter) through the compressor pipeline, liquid separation tank, buffer tank and discharge joint of the compressor cylinder. If conditions permit, the compressor inlet valve can be opened when necessary to replace the compressor and process system at the same time. ②When the compressor system is filled with nitrogen and has a certain pressure, open the compressor pipeline and cylinder discharge valve to discharge the nitrogen to relieve the pressure. At this time, it must be ensured that the pressure in the system is always greater than the atmospheric pressure to prevent air from leaking into the system. Then close the discharge valve and fill the system with nitrogen, and repeat this process until the oxygen content of the gas sampled and analyzed everywhere in the system is less than 0.5%. ③After the nitrogen pressure is stable, the sealing system should be put in time and run normally before introducing the compressed medium. ④Check the replacement status of the process system and accept it after passing the inspection. Care must be taken when replacing gas: ①Before the formal introduction of process gas, the interlocking debugging work of the compressor oil system should be completed, and all test results should meet the design requirements. ②For compressors with high inlet gas pressure, the inlet valve should be opened particularly slowly when replacing it, and it is strictly forbidden for the gas flow to cause the rotor to rotate. ③The dry gas seal of the compressor does not leak, and the pipelines of each system do not leak. If leakage is found, the cause must be found in time and try to eliminate it. 3. The centrifugal compressor unit must make all preparations for starting the compressor, and only after passing the inspection and acceptance can the centrifugal compressor unit be started according to the procedures stipulated in the regulations. For turbine-driven centrifugal compressors, the speed gradually increases from low to high after starting. There is no overload problem due to excessive speed increase like motor-driven compressors. Therefore, the inlet valve is generally fully opened, and the anti-surge return valve or vent valve is fully opened. After preparations are made in accordance with the requirements of the relevant process, all instruments and interlocks are put into use, and the water in the intercooler is smooth. After everything is ready, the pipes should be warmed, cranked, the rotor driven and the engine warmed up in accordance with the steam turbine operating procedures. Warm up the engine and run it stably for half an hour at 500~1000r/min. Comprehensively check the unit, including the oil temperature and oil pressure of the lubricating oil system, especially the bearing oil temperature. ； Check and adjust the temperature and pressure of the power oil system, vacuum system, turbine seal system, steam system and the inlet and outlet gases of each section of the compressor, and whether there are any abnormal sounds. If everything is normal, the turbine warm-up meets the requirements, and the lubricating oil tank oil temperature reaches above 32°C, the speed can be started. When the oil temperature reaches 40°C, you can stop heating the oil and allow cooling water to flow through the oil cooler. The unit increases speed according to the prescribed speed increase curve. During the speed-up process, be careful not to stay within the ±10% speed range close to the critical speed of any rotor. When passing the critical speed, the speed should be increased quickly. Generally, it is appropriate to increase the design speed by about 20% per minute. When passing the critical speed, pay close attention to the vibration of the unit. After leaving the critical speed range, the design speed can be increased by 7% per minute. From the low speed of 500 to 1000 r/min to the normal operating speed, appropriate stops should be made in stages to avoid pressure fluctuations in the steam pipe network due to too rapid changes in steam load. It also facilitates a thorough inspection of the operation of the unit. Only when everything is normal can the speed continue to increase until the lowest speed at which the governor takes effect (generally about 85% of the design speed). 4. Compressor boost After the compressor is running, the exhaust of the compressor is vented or refluxed. At this time, the exhaust pressure is very low, and no gas is delivered to the process pipe network, and the speed is not high. At this time, the compressor is at no load, or to be precise, it is running at low load. Long-term light load operation is detrimental to both the turbine and the compressor. For steam turbine units, long-term low-load operation will accelerate the wear of the steam turbine regulating steam valve. ； The turbine can achieve very high torque at low speeds. If the weight flow through the compressor is high, excessive stress may occur on the unit's shaft. ； In addition, long-term low-pressure operation also affects the efficiency of the compressor and has a negative impact on the sealing system. Therefore, after the unit is stable and operating normally, it is very necessary to increase the voltage and load in a timely manner. Boosting should generally start after the turbine speed regulator has been put into operation and reaches normal speed. Compressor boosting (loading) can be achieved by increasing the speed and turning down the pressure until the vent valve or bypass return valve is closed. However, this operation must be done carefully and cannot be performed too fast or too hastily to avoid surge. Several issues need to be paid attention to when boosting the compressor: ①Some compressor pressure increases are achieved by first closing the vent valve, some by closing the bypass valve, and some units have more than one vent valve. These vent valves or bypass valves are open when the compressor is started. In order to increase the outlet pressure, the vent valve or bypass valve can be gradually closed. During the process of closing the valve and boosting pressure, pay close attention to surge. When signs of surge are found, open the large valve in time. After the outlet vent valve is fully closed, gradually open the flow control valve. At this time, the flow is mainly controlled by the flow control valve. When the vent valve is fully closed, the anti-surge flow control valve is put into automatic control. Gradually close the flow control valve and the compressor outlet pressure rises to the specified value. During the valve closing process, care must also be taken to avoid surge. If the pressure cannot reach the predetermined value through valve adjustment, the turbine needs to be increased in speed, but the speed should not be increased too fast to prevent compressor surge. ②The general principle of the boost operating procedure is to avoid the outlet pressure being lower than the inlet pressure within each stage of the compressor and to prevent the operating point from falling into the surge zone. The correct sequence and operation gradient for closing each vent valve and bypass valve should be determined for each unit. The outlet valve of the compressor can only be opened to deliver gas to the pipeline network when the pressure in the compressor pipeline is equal to or slightly higher than the pressure in the pipeline system at normal speed. ③When boosting, attention should be paid to controlling the water volume of the intercooler to keep the inlet air temperature of each section at the specified value. ④After the pressure is increased, set the anti-surge automatic control valve to the "automatic" position. Special attention should be paid to the fact that the compressor is absolutely not allowed to operate in a surge state. The signs of compressor surge can be seen in the strong vibration and roar of the compressor, as well as severe fluctuations in outlet pressure and flow. If signs of surge are found, the vent or bypass valve should be opened until pressure and flow stabilize. 5. Compressor anti-surge test. For safety reasons, before the compressor is integrated into the process pipe network, the anti-surge automatic device should be tested to check whether its action is reliable. This test must be performed especially when starting up for the first time. Before the test, the characteristic line of the compressor should be studied to see what the surge flow rate of the compressor is at the running speed and what the current running flow rate is. The compressor does not surge, and of course the delivered flow rate is greater than the surge flow rate. Then change the setting value of the anti-surge flow control valve and adjust the flow control setting value to the running flow rate. At this time, the anti-surge automatic vent valve or return valve should automatically open. If it fails to open, it means that the automatic anti-surge system is malfunctioning and should be checked and eliminated in time. During the test, be careful not to cause the compressor to surge. 6. Pressure maintenance and grid-connected air supply of the compressor. When the steam turbine reaches the working speed of the governor, the compressor boosts the pressure to adjust the outlet pressure to the specified pressure. The compressor unit is checked to confirm that everything is normal and the operation is stable. At this time, the main control room can be notified to prepare for air guidance to the system, that is, the high-pressure gas from the compressor outlet pipeline of the process department is introduced to each gas-consuming part. When the compressor outlet pressure is greater than the process system pressure and the air guidance command is received, the compressor outlet valve can be gradually and slowly opened to supply air to the system to avoid sudden changes in the compressor operating conditions due to no pressure in the system or too much pressure. When each gas-consuming part introduces the gas in the compressor outlet pipeline into each process system, as the air conduction volume increases, the compressor outlet pressure will inevitably decrease. Therefore, while guiding air, the compressor must perform "pressure maintenance", that is, maintain the stability of the outlet pressure through flow adjustment. When adjusting the flow rate during air guidance and pressure maintenance, care must be taken to prevent surge. Before adjusting, the surge flow rate should be remembered so that the adjusted flow rate is not close to the surge flow rate. ； During the adjustment process, attention should be paid to the movement of the unit. When signs of surge are found, the vent flow or return flow should be increased in time to prevent surge. If the specified outlet pressure cannot be reached through flow adjustment, the turbine must speed up at this time. Under normal gas supply operating conditions of the process system, all anti-surge return valves or vent valves should be fully closed. Only when production is reduced while maintaining the original pressure, the backflow valve or vent valve is allowed to be slightly opened as a last resort to keep the power consumption of the compressor at a minimum. After entering normal production, all manual operations should be switched to automatic control. At the same time, the operation of each part of the unit should be checked on time. Pay special attention to the temperature of the bearing or the temperature of the bearing oil return. If there is any abnormality, it should be dealt with in time. Always pay attention to the changes in gas parameters at the compressor outlet and inlet, and adjust the unit accordingly to avoid surge. 7. Routine inspection during operation. When the unit is operating normally, the machine must be inspected regularly. Some data that are not automatically recorded by the instrument should be recorded on the machine data recording paper by the operator in order to grasp all the conditions of the machine during operation, conduct comparative analysis, help understand the performance, and deal with problems in a timely manner. When the compressor unit is running at normal speed, the following inspections are generally required: ①Turbine inlet pressure and temperature ； ②Extraction steam flow, temperature and pressure ； ③Condenser vacuum degree ； ④Fuel tank level ； ⑤The oil temperature is within the specified range ； ⑥Oil pressure (including oil pump outlet oil pressure, filter oil pressure drop, oil main oil pressure, bearing oil pressure, and nitrogen pressure of dry gas seal) ； ⑦Oil flow in the oil return pipe (samples are regularly taken from the main oil tank for analysis) ； ⑧The axial thrust of the compressor, the axial displacement of the rotor and the vibration level of the unit ； ⑨The temperature and pressure of the gas at the inlet and outlet of each section of the compressor and the water temperature at the inlet and outlet of the cooler. 8. Compressor shutdown There are two types of compressor unit shutdown. One is planned shutdown, which is normal shutdown and manual shutdown. ； The other is an emergency shutdown, that is, an accident shutdown, which is an automatic shutdown due to the action of the security system, or a manual "opening" of the gate for emergency shutdown. The operating points and procedures for planned shutdown are:: ①After receiving the shutdown notice, set the automatic flow control valve to the "manual" position, use the main control room control system or on-site to open the bypass valve or vent valve of each section, close the outlet valve, cut off the compressor from the process system, and all perform self-circulation. ②The turbine is decelerated from the main control room or on site to the minimum speed of the governor. Slowly reduce the speed while reducing the load to avoid compressor surge. ③Shut down the steam turbine according to the steam turbine shutdown requirements and procedures. ④The lubricating oil pump and sealing oil pump should be stopped after the unit is completely shut down and cooled down. ⑤If the inlet valve of the compressor can be closed according to the regulations, it should be closed ； If the valve is required to be open and under pressure, the sealing system must remain operational. ⑥The lubricating oil pump and sealing oil pump must be kept running until the temperature at the outlet end of the compressor casing drops below 20°C. Check the lubricating oil temperature and adjust the water volume of the oil cooler to keep the outlet oil temperature at about 50°C. ⑦After parking, open the compressor casing and intercooler discharge valve, and close the intercooler water inlet valve. All drain valves or plugs on the compressor casing should be opened after shutdown to drain condensate, and then closed again before starting the machine next time. ⑧If there is still some residual pressure in the compressor after the compressor is shut down, the sealing system should continue to operate, the sealing oil tank heating coil should continue to heat, and the high-level oil tank and sealing oil collector should remain stable. If the ambient temperature drops below 5°C, in some pipeline systems, the accompanying pipes of the system should be heated and insulated. 3. Compressor anti-reverse It is strictly forbidden to reverse the compressor after it is stopped. When the compressor rotor is stationary, there is still a large capacity of process gas remaining in the pipeline and has a certain pressure. At this time, the compressor rotor stops rotating, and the pressure inside the compressor is lower than the pipeline pressure. At this time, if there is no check valve installed on the compressor outlet pipeline or the check valve is far away from the compressor outlet, the gas in the pipeline will flow backward, causing the compressor to reverse, and at the same time, it will also drive the rotors of the steam turbine or electric motor and gear transmission to reverse. The reversal of the compressor unit rotor will destroy the normal lubrication of the bearings, change the stress condition of the thrust bearing, and even cause the loss of the thrust bearing. The dry gas seal will also be damaged due to the reversal of the compressor. In order to avoid compressor reversal, several issues should be paid attention to: ①A check valve must be installed on the compressor outlet pipeline and installed as close to the outlet flange as possible to minimize the distance between the check valve and the compressor outlet, thereby minimizing the gas capacity in this section of the pipeline and preventing reversal. ②According to the conditions of each unit, a vent valve, exhaust valve or recirculation pipeline should be installed. When shutting down, these valves should be opened in time to remove high-pressure gas from the compressor outlet to reduce the gas capacity stored in the pipeline. ③The gas in the system may backflow when the compressor is shut down. High-pressure and high-temperature gas backflows back into the compressor, which will not only cause the compressor to reverse, but also burn out the bearings and seals. Due to the gas backflow causing many accidents in the country, it is very worth noting! In order to effectively prevent the occurrence of the above accidents, the following tasks must be done before slowing down or stopping the machine.: ①Open the vent valve or reflux valve to vent or reflux the gas. ②Securely close the check valve of the system pipeline. After doing the above work, gradually reduce the speed and stop the machine. 4. Operation of the compressor in a closed circuit Due to certain special needs of the compressor, it may be operated in a closed circuit. Operating in a closed circuit with air, oxygen and oxygen-containing gases is dangerous and can easily lead to explosions. It is therefore not allowed to operate in closed circuits using these gases as media. Gas combustion and explosion generally require three conditions, namely fuel, combustion accelerant and heat. The generation of heat is that after the gas is compressed, the temperature increases significantly as the pressure increases. ； It is inevitable that the compression work added to the gas is converted into heat and is contained in the gas. Heat alone without fuel or combustion accelerant will not cause combustion or explosion. If the compressed medium is air, oxygen or a gas containing oxygen, this provides combustion-supporting conditions. The fuel is generally oil, that is, the lubricating oil, sealing oil that leaks into the cylinder and comes into contact with the medium, or the oil that remains during installation and maintenance. These factors together can easily cause combustion and explosion. In order to avoid combustion and explosion, one of the three factors that constitute combustion and explosion-oxygen, oil and heat must be eliminated. However, heat cannot be eliminated, so we have to eliminate oil and oxygen. To prevent explosions, air or other oxygen-containing gases are never allowed to be operated within the closed circuit of the compressor. If it is necessary to use closed loop operation due to certain needs (such as inspection, commissioning, etc.), inert gases (such as helium), nitrogen or carbon dioxide should be used according to the required molecular weight. Preventing oil from entering the compressor and coming into contact with gas is also an important measure to prevent explosions. It is important to ensure that the internal parts of the compressor and connecting pipelines are clean and oil-free. This is particularly important for compressing oxygen-containing gaseous media. Before the compressor sealing system is put into operation, lubricating oil should not pass through the bearings ； Before shutting down the sealing system, the lubricating oil pump should be stopped first ； When the pressure in the sealing system is insufficient, the compressor should automatically stop. The above is only a general introduction, and relevant special regulations should be followed for specific precautions. 5. Compressor surge and anti-surge A special phenomenon in the operation of centrifugal compressors is surge. Preventing surge is an extremely important issue in compressor operation. Many facts have proven that a large number of compressor accidents are related to surge. Surge can cause great harm because the air flow produces strong reciprocating pulses during surge, which impacts the compressor rotor and other components back and forth. ； Strong and irregular oscillations of air flow cause strong vibration of the unit, resulting in various serious consequences. Surge once caused the large rotor shaft to bend ； The seal is damaged, causing serious air leakage and oil leakage. ； Surge increases the axial thrust and burns the thrust bearing ； Destroy alignment and installation quality, aggravate vibration ； Strong vibration can cause instrument failure ； Severe and persistent surge can cause the rotor to collide with the stationary part, break the main shaft and diaphragm, or even the entire compressor to be scrapped. This has already happened abroad. Surge is a problem that must be guarded against at all times during operation. 1. Signs of surge During operation, the signs of surge in the compressor usually include a significant drop in flow rate, a significant reduction in compressor displacement, fluctuating outlet pressure, the pointer of the pressure gauge swinging back and forth, and the unit experiencing strong vibrations accompanied by intermittent low roars, as if a person is coughing. In addition to judging surge by human feeling, it can also be detected based on instruments and operating parameters combined with performance curves. 2. Conditions for surge occurrence. According to the principle of surge, surge occurs under the following conditions:: ①When the flow rate decreases, it occurs when the flow rate drops to the surge flow rate at this speed. The characteristics of the compressor determine that under a certain speed, a certain flow corresponds to a certain outlet pressure or pressure boost ratio, and at a certain speed, there is a limit flow - surge flow. When the actual flow rate during compressor operation is lower than the surge flow rate, the compressor cannot operate stably and surge occurs. The comprehensive relationship between these flows, outlet pressure, speed and surge flow constitutes the compressor's characteristic line, also called the performance curve. If the flow rate is greater than the surge flow rate at a certain speed, surge will not occur. ②When the pressure of the gas in the pipe network system is greater than the corresponding maximum pressure at a certain speed, surge occurs. If the compressor is operated in conjunction with the system piping network, when the system pressure * * When the pressure is higher than the limit pressure corresponding to the compressor operating at this speed, the high-pressure gas in the system will form a very high "back pressure" at the compressor outlet, causing the compressor outlet to be blocked, the flow rate to be reduced, and even the pipe network gas to flow back. ； The inlet air source is reduced or cut off. For example, the air supply to the compressor is insufficient, and the compressor has no supplementary air source. If all these conditions are not discovered and adjusted in time, the compressor may surge. ③Surge may occur when mechanical parts become damaged and fall off. Insufficient installation of mechanical seals, balance plate seals, O-rings and other components, inaccurate installation positions or falling off will cause air leakage between stages or sections, which may cause surge. ； If the filter resistance is too large and the check valve fails or is damaged, it will also cause surge. ④During operation, increasing the speed and pressure too quickly and failing to reduce the pressure first before slowing down may cause surge. The speed and pressure should be increased slowly and evenly. Before reducing the speed, pressure relief measures should be taken, such as venting and reflux, to avoid backflow of air after the speed is reduced. ⑤The operating conditions change and the operating point falls into the surge zone. Changes in working conditions, such as changing speed, flow rate, and pressure, without checking the characteristic curve before changing the speed, flow rate, and pressure, causing the compressor operating point to fall into the surge zone. ⑥During normal operation, the anti-asthma system is not turned on automatically. When external factors change, such as steam pressure drops or steam volume fluctuations ； The turbine speed dropped and the anti-surge system had no time to adjust manually. ； or interruption of breathing, etc. ； Surge may occur due to failure to use the automatic anti-surge device. ⑦Media status changes. The occurrence of surge may have a lot to do with the state of the gas medium, because the state of the gas affects the flow rate, which also affects the surge flow rate. Of course, it affects surge. For example, the intake air temperature, intake pressure, gas composition, or molecular weight, etc. all have an impact on surge. When the rotational speed and outlet pressure remain unchanged, surge is likely to occur as the gas inlet temperature increases. ； When the rotation speed is constant, the higher the inlet pressure, the greater the surge flow rate. When the intake pressure is constant, the outlet pressure is constant, the rotation speed remains unchanged, and the gas molecular weight is greatly reduced, surge is likely to occur. 3. Reasons for surge during operation: ① The system pressure is extremely high. The reasons for this situation include emergency shutdown of the compressor and failure to vent or return the gas. ； The one-way check valve on the outlet pipeline does not operate properly or is not closed tightly. ； Or the one-way valve is too far from the compressor outlet, the gas capacity in front of the valve is very large, the system suddenly decreases, the compressor has no time to adjust, the anti-surge system is not activated automatically, etc. ②Insufficient suction flow. Due to external reasons, the suction volume is reduced below the surge flow rate. However, the speed has not changed, causing the compressor to enter the surge zone and cause surge. The compressor inlet filter is blocked, the resistance is too large, and the compressor speed cannot be adjusted. ； This may happen if the filter element is too dirty or if it freezes in winter. 4. Methods to prevent and eliminate surge. The fundamental measure to prevent and eliminate surge is to try to increase the inlet gas flow of the compressor. For general non-toxic and non-dangerous gases such as air, carbon dioxide, etc., venting can be used ； Reflux circulation can be adopted for gases such as natural gas, synthesis gas and ammonia. Using the above method can increase the gas flow through the compressor and eliminate surge ； However, the pressure decreases accordingly, resulting in a waste of power and reduced economy. If the system needs to maintain equal pressure, the rotation speed should be increased after venting or refluxing to bring the discharge pressure to the original level. Before increasing pressure, reducing speed, and shutting down, the vent valve or return valve should be opened in advance to reduce back pressure, increase flow, and prevent surge. The anti-surge margin should also be controlled based on the compressor performance curve, and the anti-surge system should be put into automatic operation during normal operation. Before increasing the speed or voltage, be sure to check the performance curve in advance, select the next operating point, and control the voltage and speed according to the anti-surge safety margin. The anti-surge safety margin is the ratio of the normal working flow to the surge flow at a certain working speed. Generally, the normal working flow should be 1.05 to 1.3 times larger than the surge flow. If the margin is too large, although it is not easy to surge, the pressure will drop a lot, the waste will be great, and the economy will decrease. In actual operation, it is best to set the setting value of the anti-surge valve (backflow control valve) according to the anti-surge margin. If it is too large, it is uneconomical, and if it is too small, it is unsafe. After the anti-surge system is adjusted according to the safety margin, the anti-surge valve should be closed and put into automatic operation during normal operation, which is both safe and economical. Some units do not operate the anti-surge device automatically, but use it manually. They dare not close the anti-surge valve strictly for fear of surge. During normal operation, a large amount of gas will flow back or vent. This is neither economical nor safe, because when surge occurs, manual operation is too late, and the result is that surge cannot be prevented. When boosting voltage and changing speed, it is necessary to emphasize the principle that "when boosting voltage, the speed must be raised first, and when reducing speed, the voltage must be lowered first." The compressor should be boosted after the turbine speed regulator is put into operation. ； Before boosting the pressure, check the performance curve to determine the speed that should be reached, and then increase the pressure after the speed reaches that speed. ； The compressor speed reduction should be started after the anti-surge valve is properly arranged. ； The speed and pressure cannot be increased too fast or too fast. ； The speed and pressure reduction should also be slow and even. The anti-surge valve must be opened and closed slowly and alternately, and the operation should not be too violent to avoid excessive shaft displacement and aggravation of axial thrust and vibration. If the compressor unit has more than two anti-surge valves, they should be opened or closed alternately to make the pressure of each cylinder change evenly, which is beneficial to the coordination of the stress, anti-surge and sealing systems of each cylinder. Section 5 Accident Handling of Centrifugal Compressors The performance of centrifugal compressors is affected by suction pressure, suction temperature, suction flow, molecular weight composition of the intake air, and the speed and control characteristics of the prime mover. Generally, it is most common for multiple reasons to interact with each other to cause failures or accidents. The possible causes and treatment measures for common failures are listed in the table below. 1. Possible reasons for compressor performance not meeting the requirements. Treatment measures: ① Design errors. Review the original design and check whether the technical parameters meet the requirements. If problems are found, negotiate with the seller and manufacturer and take remedial measures. ② Manufacturing errors. Check the original design and manufacturing process requirements, check the material and its processing accuracy. If problems are found, negotiate with the seller and manufacturer in a timely manner. ③ Gas Difference in physical performance Check various performance parameters of the gas. If the gas performance is too different from the original design, it will inevitably affect the performance indicators of the compressor. ④ Changes in operating conditions should identify the reasons for the changes. ⑤ Deposited inclusions. Check whether there are inclusions in the gas flow channel, impeller and cylinder. If there are inclusions, they should be removed. ⑥ If the gap is too large, check the clearance of each part. Those that do not meet the requirements must be adjusted. 2. Possible causes and solutions for insufficient compressor flow and discharge pressure ① If there is a problem with the flow rate, compare and study the discharge pressure and flow rate with the compressor characteristic curve to see if they match, so as to find the problem ② Check the direction of rotation when the compressor is reversed, it should be consistent with the direction of the arrow mark on the compressor casing ③ If the suction pressure is low, compare it with the instruction manual to identify the cause. 4. The molecular weight does not match. Check the actual molecular weight and chemical composition of the gas and compare it with the specified value in the instruction manual. If the actual molecular weight is smaller than the specified value, the exhaust pressure is insufficient. 5. The operating speed is low. Check the operating speed and compare it with the instruction manual. If the speed is low, increase the speed of the prime mover. ⑥ The circulation volume from the exhaust side to the suction side increases. Check the circulating air volume, check the external piping, and check the opening of the circulating air valve. If the circulation volume is too large, adjust it. ⑦ Check the pressure meter or flow meter for failure. Check each measuring instrument. If any problem is found, adjust, repair or replace it. 3. Possible causes of discharge pressure fluctuations. Treatment measures ① If the flow rate is too small, increase the flow rate. If necessary, install a new valve on the discharge pipe. Use the bypass pipe to supplement the flow. 2. The flow regulating valve is defective. Check the flow regulating valve and solve the problem promptly. 4. Possible reasons for the flow and pressure to be zero when the compressor is started. Treatment measures. 1. There is a problem with the rotating system, such as the impeller key and connecting shaft. Treatment measures ① Improper position of the inlet guide vane, check whether the inlet guide vane and its positioner are normal, especially check whether the actual position of the inlet guide vane is consistent with the indicator reading. If it is improper, the inlet guide vane and positioner should be readjusted. ② The anti-surge valve and the vent valve are abnormal. Check whether the anti-surge sensor and the vent valve are normal. If there are any abnormalities, they should be corrected and adjusted to make them work smoothly, without vibration and oscillation, and prevent air leakage. ③ Compressor surge. Check whether the compressor is surged and whether the flow rate is enough to disengage the compressor. Surge zone, especially to ensure that the inlet temperature of each stage is normal ④ The sealing gap is too large, adjust the sealing gap or replace the seal as required ⑤ The inlet filter is clogged, check the inlet pressure, pay attention to whether the gas filter is clogged, clean the filter 6. Possible causes of high gas temperature Treatment measures ① Insufficient cooling water volume Check whether the cooling water flow, pressure and temperature are normal, readjust the water pressure and water temperature ② The cooling capacity of the cooler decreases Check the cooling water volume, the water velocity in the cooler tube should be less than 2m/s ③ Dirt on the surface of the cooling tube. Check the temperature difference of the cooler to see if the cooling effect of the cooling tube is reduced due to scaling. Clean the cooler tube. ④ The cooling tube is broken or the fit between the tube and the tube plate is loose. The two ends of the damaged tube are blocked or use a tube expander to loosen the tube. The moving pipe end is swollen. ⑤ There are bubbles accumulated in the water side channel of the cooler. Check whether there are bubbles in the water side channel of the cooler. Open the vent valve to discharge the gas. ⑥ The operating point deviates too much from the design point. Check whether the actual operating point deviates too much from the specified operating point. Adjust Operating conditions 7. Possible causes and solutions for abnormal vibration and abnormal noise of the compressor ① The alignment accuracy of the unit is destroyed and misalignment. Check the vibration of the unit. The axial amplitude is large, and the vibration frequency is the same as the rotational speed, sometimes 2 times or 3 times... Remove the coupling and let the prime mover rotate alone. If the prime mover has no abnormal vibration, it may be misaligned and should be re-aligned. ② The rotor is unbalanced and check the vibration. If the radial amplitude is large, the vibration frequency is n, and the amplitude is proportional to the unbalance amount and n2. ； At this time, the rotor should be inspected to see if there is dirt or damage. If necessary, the rotor should be rebalanced. ③ Friction and damage of the rotor impeller. Check the rotor impeller to see if there is friction and damage. Repair and replace if necessary. ④ Spindle bending. Check whether the spindle is bent, and repair if necessary. Correct the straight shaft ⑤ If the coupling is faulty or out of balance, check the coupling and remove it, check the dynamic balance, and repair it ⑥ If the bearing is abnormal, check the bearing radial clearance and make adjustments. Check the interference between the bearing cap and the bearing pad back. If it is too small, it should be increased. ； If the bearing alloy is damaged, replace the tile, ⑦ and the sealing plate is not properly sealed, the sealing plate rubs, the vibration pattern is irregular, and the sound of metal friction can be heard when starting or stopping. Repair or replace the sealing ring ⑧ Gear increaser gear meshing is poor. Check the gear increaser gear meshing. If the vibration is small, but the vibration frequency is high, which is a multiple of the number of teeth, and the noise changes rhythmically, the non-parallelism between the meshing gears should be re-corrected. 9. The anchor bolts are loose and the foundation is not strong. Repair the foundation and tighten the anchor bolts. ； If the oil temperature is low, heat the lubricating oil. ⑾ There is dirt in the oil and it is not clean, causing the bearings to wear. Check the oil quality, strengthen filtration, and change the oil regularly. Check the bearings and replace them if necessary. ⑿ Inclusions intruding or adhering to the machine. Check the rotor and cylinder air flow channels and clear debris. ⒀ Immerse the machine in condensate water. Check the inside of the compressor and remove the condensate water. ⒁ Compressor surge. Check whether the compressor is running away from the surge point. Whether the anti-surge margin is sufficient, change the operating condition point according to the prescribed performance curve, increase the suction volume, and check whether the anti-surge device is working properly. ⒂ The gas pipeline has additional stress on the casing. The gas pipeline should be well fixed to prevent excessive stress from acting on the compressor cylinder. ； The pipeline should have sufficient elastic compensation to cope with thermal expansion. ⒃ There are machines working near the compressor to separate its foundation and base from each other, and increase the elasticity of the connecting pipe. ⒄ Adjust the throttle valve opening for sudden changes in compressor load. ⒅ Loose parts and fasten parts, and add anti-loosening facilities. 8. Possible causes of compressor surge. Treatment measures ① The operating condition point falls into the surge zone or is too close to the surge boundary. Check the position of the compressor operating condition point on the characteristic curve. If it is too close to the surge boundary or falls into the surge zone, break away from the surge in time and eliminate the surge. ② The anti-surge margin is not set correctly. The pre-set anti-surge margin under various working conditions should be controlled at about 1.03~1.50, and should not be too small. ③ The suction flow is insufficient, the intake valve opening is not enough, the filter element is too dirty or frozen, the air inlet channel is blocked, and the inlet air source is reduced or cut off. The cause should be found out and corresponding measures should be taken. ④ The compressor outlet gas system pressure exceeds the limit. When the compressor decelerates or shuts down, the gas is not vented or does not flow back. The outlet check valve is malfunctioning or loose, causing gas backflow. The cause should be found out and corresponding measures should be taken. ⑤ The working conditions change. When the inlet flow decreases or the rotational speed drops, or the rotational speed increases rapidly, the characteristic line should be identified, and the anti-surge valve or return valve should be opened in time. ⑥ The anti-surge device is not activated automatically. During normal operation, the anti-surge device should be activated automatically. ⑦The anti-asthma device or mechanism is not working accurately or malfunctioning. Regularly check the working condition of the anti-asthma device. If it is found that it is malfunctioning, inaccurate or stuck, or the movement is not working properly, it should be repaired and adjusted in time. ⑧The anti-asthma setting value is not allowed. Strictly set the anti-asthma value and test it regularly. If it is found, The numerical value is not allowed to be corrected in time ⑨ The speed increase and pressure increase are too fast. The operating conditions change. The speed increase and pressure increase should not be too sharp or too fast. They should be slow and even. ⑩ The pressure should be lowered before the speed decreases. Only by reasonable operation can the occurrence of surge be avoided. ⑾ The gas properties change or The gas state changes seriously. Before the gas properties or state change, the characteristic curve should be converted and the anti-surge value should be set according to the changed characteristic line. ⑿ The compressor parts are damaged and fall off. The interstage seal, balance plate seal and "O" ring are damaged and fall off, which will induce surge. They should be checked frequently to keep them in good condition. ⒀ The check valve on the compressor gas outlet pipeline is not working. Always check the check valve on the compressor outlet gas pipeline to keep the action flexible and reliable to avoid speed reduction or shutdown. Backflow of gas 9. Possible causes of abnormal machine sound and treatment measures ① Machine is damaged and shut down for inspection and repair ② The machine is running unstable and adjusts the process parameters. If it cannot be adjusted immediately, please ask for shutdown and inspection ③ Friction of bearings and seals Check the bearings and seals for repair or replacement If the O" ring is found to be defective or deteriorated, it should be replaced. ③ Cylinder or pipe joints are leaking. Check the cylinder joint surface and each flange joint. If air leakage is found, take timely measures. ④ Sealant failure. Check the sealant and packing in the middle face and other parts of the cylinder. Replace if found to be defective. ⑤ The sealing floating seat is too soft and cannot move. When parts are corroded, the material should be replaced. When solid matter is found inside the sealing part and sealing spring, the gas composition should be analyzed. ⑥ Abnormal operation. Check whether the operation is correct and problems are found. ⑦ Seals are damaged, broken, corroded, and worn. Check each sealing ring. If breakage, breakage, wear, and corrosion are found, identify the cause and take measures to solve it. 11. Possible causes of bearing failure. Treatment measures ① Abnormal lubrication. Make sure to use qualified lubricating oil, check regularly, and there should be no water and dirt entering the oil. ② Check the alignment for misalignment, and make corrections and adjustments if necessary. ③ The bearing clearance does not meet the requirements. Check the clearance, and adjust or replace the bearing if necessary. ④ Compressor Or the coupling is unbalanced. Check the compressor and coupling to see if there is dirt attached or parts are missing. If necessary, rebalance it. 12. Possible causes of thrust bearing failure and treatment measures ① The axial thrust is too large. Check whether the coupling is clean and assemble it. It is forbidden to transmit excessive axial thrust to the compressor through the prime mover coupling. ② If the lubrication is abnormal, check the oil pump, oil filter and oil cooler, check the oil temperature, oil pressure and oil quantity, check the quality of the oil, and deal with it in time if it does not meet the requirements. 13. Possible causes and measures for rising bearing temperature: ① The oil pipe is not smooth, the filter is clogged, and the oil volume is small. Check and clean the oil pipeline and filter, and increase the oil supply. ② The bearing oil inlet temperature is high and increase the water volume of the oil cooler. ③ The bearing clearance is too small or insufficient. Scrape the bearing bush evenly and adjust the amount of bushing. ④ The lubricating oil contains water or deteriorates. Analyze the oil quality and replace it with new oil. ⑤ Dust or impurities invade the bearing. Clean the bearing. Reasons ⑧ The oil wedge of the thrust bearing is small or reversed. Replace the bearing block. ⑨ The aperture of the oil inlet throttle valve of the bearing is too small and the oil inlet is insufficient. Increase the diameter of the throttle ring appropriately. ⑩ The cooling water of the oil cooler is insufficient and the inlet oil temperature is too high. Adjust the cooling water of the oil cooler. The amount of water inflow ⑾ The babbitt alloy grade of the bushing is incorrect or the casting is defective. Re-cast the babbitt alloy grade specified in the drawing ⑿ The lining oil groove is too small. Properly deepen and enlarge the oil groove. 14. Possible causes of alarm due to increased shaft displacement. Treatment measures ① Shaft If the axial displacement instrument fails, check the instrument failure and deal with it. ② The thrust bearing is damaged. Repair or replace the tiles. ③ The machine operation is unstable. Find out the cause and eliminate it. ④ Check the axial displacement system for poor installation and perform maintenance and adjustment. ⑤ The oil pipe is clogged. , the amount of oil in the bearing bush is small, check and clean the oil circuit ⑥ The machine vibrates, the temperature of the bearing bush rises, emergency stop, check and repair 15. Possible causes of oil seal ring and seal ring failure Treatment measures ① Please refer to the vibration section for misalignment and vibration ② Dirt in the oil Check the oil filter, replace the filter element with dirt, and check the cleanliness of the pipeline. ③ There is deviation in the sealing ring gap. Check the gap, and adjust or replace the sealing ring if necessary. ④ Insufficient oil pressure. ； Check the sealing oil temperature and adjust it. ③ The oil and air pressure difference system is not working properly. Check the reference air pressure and circuit and adjust it to the specified value. ； Check the working condition of each component of the differential pressure system. ④ The seal is partially worn or damaged. Remove the seal and reassemble it, and repair or replace it according to regulations. ⑤ If the seal ring is not worn, the contact surface of the shaft sleeve, impeller hub, etc. and the seal should be lightly ground and corrected to a right angle. ⑥ The end face of the floating seat has a gap or the sealing surface is worn. Eliminate suction damage and reduce Wear, replace with a new one if necessary ⑦ If the contact of the floating seat is not the same, grind and correct the contact surface or replace it with a new one ⑧ When the sealing ring is broken or damaged, be careful not to damage it and minimize the no-load. If it cannot be repaired, replace it If the sealing part is frozen during low-temperature operation, it is possible to eliminate the icing, or use dry nitrogen to purify the sealed atmosphere. ⑾ Check the measuring instrument working error of the measuring instrument system. If any inaccuracy is found, it should be repaired or replaced. 17. Possible causes of compressor impeller damage. Treatment measures ① The material is unqualified and the strength is not enough. Re-examine the original design and manufacturing. If the material is unqualified, the impeller should be replaced. ② Poor working conditions lead to a decrease in strength. The working conditions do not meet the requirements. Due to poor conditions, the strength is reduced. The working conditions should be improved to make it meet the design requirements. ③ The load is too large and the strength is reduced. The speed is too high or the flow rate and pressure ratio are too high, which reduces the strength of the impeller and causes damage. ； Severe overloading or overspeed operation is prohibited. ④ Abnormal vibration. The collision and vibration of the dynamic and static parts are too large, causing the rotating part to contact and collide with the stationary part, causing damage. It is strictly prohibited to operate with excessive vibration value. ； Eliminate abnormal vibration ⑤ Inclusions falling into the compressor may damage the impeller or other components ； Inclusions are strictly prohibited from entering the compressor, and the inlet air should be filtered. ⑥ Immersion in condensate water. Condensate water immersion or moisture in the gas condenses in the machine, which may cause water hammer and corrosion. Water intrusion and water accumulation must be prevented. ⑦ Deposited inclusions keep the gas pure. Sediments in the flow-through part and the cylinder should be removed in time. (8) Stress corrosion and chemical corrosion prevent stress concentration. ； Prevent harmful components from entering the compressor ； Take anti-corrosion measures for the compressor. 18. Possible reasons for the abnormal sound of the gear speed increaser. Treatment measures: ① The gear suddenly breaks due to overload or impact load (fatigue break or load concentration break). Repair or replace the gear. ； It should be smooth and slow when starting, and the operation should be stable ② Fatigue pitting corrosion, bonding distress or plastic deformation of the gear tooth surface Repair and adjust the gear, or replace the gear if it is serious ③ Poor meshing of the gear working surface Reinstall and adjust the meshing of the gear ④ Gear gap is not suitable and readjust the gap 19. Possible causes of increased gear vibration Treatment measures ① If the gear is worn or damaged, adjust the meshing clearance or replace the gear. ② The contact accuracy of the tooth surface is poor. Improve the machining accuracy and trim the tooth surface. ③ The centerline alignment is poor. Reinstall and align. ④ The bearing gap is too small and the scraper adjustment is required. ⑤ Poor lubrication. Find out the cause and eliminate it. ⑥ Identify the cause and eliminate the source of vibration caused by the vibration of the driver or compressor. 20. Possible causes of poor gear lubrication and treatment measures: ① The oil has deteriorated, contains water or contains impurities. Conduct a chemical analysis of the oil to find out the cause and change the oil. ② The oil supply system is clogged. Check the oil system and clean it. 21. Lubricating oil pressure drop, Possible causes and measures: ① main oil pump failure, switch to check, repair the oil pump ② oil pipe rupture or oil leakage at the connection, check, repair or replace the pipe section ③ oil line or oil filter is clogged, switch and clean ④ oil tank oil level is too low and refuel ⑤ oil line control Check and adjust the system mechanism for defects. ⑥ Oil pressure automatic control or pressure gauge failure. Check, repair or replace the pressure gauge. ⑦ Bearing temperature suddenly rises. Shut down and check the Babbitt surface. 22. Possible causes of severe oil pressure fluctuations. Treatment measures. ① Mixing in the oil line. Air or other impurities open the vent valve and remove the impurities ② The oil pressure regulating valve fails, adjust the oil pressure regulating valve or replace it ③ The oil pressure gauge is defective Check, repair or replace ④ The oil pump or pipeline vibrates violently Identify the cause and eliminate the source of the vibration 23. Oil cooler Possible causes of high rear oil temperature. Treatment measures: ① Insufficient cooling water volume, increase cooling circulation water volume ② Cooler scaling, low efficiency, remove dirt ③ Lubricating oil deterioration, oil change ④ Cooling water pressure is low, water temperature is high, increase cooling water pressure, increase water volume ⑤ Pipeline failure, cooling water interruption, check the pipeline and troubleshoot 24. Possible causes of vibration, heat or noise of the main oil pump. Treatment measures: ① Poor assembly of the oil pump. Reassemble according to the diagram. ② The oil pump and the motor shaft are not concentric and re-center. ③ Ground If the anchor bolts are loose, tighten the anchor bolts. 4. If the bearing gap is large, adjust the bearing gap. 5. Tighten or add pipe clamps due to pipeline pulsation. 6. Parts are worn or damaged. Repair parts or replace them. 7. Overflow valve or safety valve is unstable. Adjust the valve or replace the valve. 25. Oil temperature Possible causes and measures for the increase: ① High outlet water temperature, increase cooling circulation water volume ② Insufficient cooling water volume, increase cooling circulation water flow ③ There are bubbles in the lubricating oil system, deterioration releases gas in the oil system, change the oil ④ Oil cooler scale accumulation reduces the cooling effect, check the oil cooler, remove the scale 26. Possible causes of lubricating oil deterioration, processing measures ① Water and compressor gas mix into the lubricating oil, causing the oil to become turbid or discolored. Check the mechanical seal of the compressor to see if the leakage is expanding. ； Check the "O" ring of the shaft sleeve and solve the problem promptly if the problem is found ② The oil level is too high and the oil foams. Stop the machine to check the oil level. If the oil quality is poor, replace it. 27. Possible causes of sudden decrease in lubricating oil volume. Treatment measures ① If the oil pump fails, check whether the main oil pump is running. ； When the main oil pump is switched, is the auxiliary oil pump running? ② The oil seal at the input shaft of the oil pump is leaking. Check the amount of oil leakage at the input shaft, and replace the oil seal if necessary. ③ There is oil leakage at the mechanical seal of the gear box. Check the mechanical seal. If there is any problem, solve it in time. 28. Possible causes of prime mover overload. Treatment measures ① The molecular weight of the gas is larger than the specified value. Check the actual molecular weight, and compare it with the instructions Compare ② If there is an electrical problem with the prime mover, check the heat capacity and operating conditions of the circuit breaker, check whether the voltage is reduced, check whether the current difference of each phase is within 3%, and solve the problem promptly if found. ③ Mechanical defects such as prime mover, gear box, compressor, etc., parts collide and disassemble the prime mover, check whether the shafts of the prime mover, gear box and other equipment are free and rotate briskly. ； Study the discharge status of lubricating oil and check whether there is metal wear powder ； Disassemble the compressor body and check whether there is any contact or scratching. ④ The surface of the diffuser adjacent to the impeller is corroded and the degree of expansion is reduced. Disassemble the machine for inspection. Check each flow channel of the diffuser. If there is corrosion, the material should be improved or the surface hardness should be increased. ； Clean the surface (wipe with emery cloth) to make the surface smooth ； If the impeller collides with the diffuser, or the diffuser is deformed, it should be replaced. ⑤ The impeller or diffuser is deformed. The impeller or diffuser is deformed and should be repaired or replaced. ⑥ The rotating part collides with the stationary part. Disassemble the prime mover, compressor and gear box, check the clearance between each part and compare it with the instruction manual. If the problem is found, solve it promptly. 7. If the suction pressure is high, the weight flow rate will be large and the power consumption will be large. Compare it with the instruction manual to find out the cause and solve it.