The problem of excess air volume adjustment in stepless air volume control!
Thread Content
Which marine engineer has knowledge of pressure regulation procedures, fault troubleshooting, and relevant precautions? What are the operational parameters on the DCS control interface? In addition to the clearance adjustment load, are parameters such as hydraulic oil pressure and gas leakage pressure also needed to be increased? Should the pressure ratio for each stage also be introduced indoors as a reference?
I’m not too familiar with clearance. I can provide a system for stepless adjustment of air volume.:o
Sure, is there any material available? Can it be shared?
You can take a look at the post I sent; it contains pictures from the site where it was operated. I can’t send the PPT materials here, so you can give me an email address and I’ll send them to you
502481336@qq.com Thank you!
The documents have been sent to your email; please check it
Feasibility Study Report on the ASSV1.0 Clearance Adjustment Control System for the 4M32-13.82/24-186 New Hydrogen Compressors of Shandong Haihua Chemical Co., Ltd. Technical Planning: Luo Xinmin, 13870209881 Project Manager: Han Tao, 18654614566 Jiangxi Jiujiang Daan Automatic Control Equipment Co., Ltd. Shandong Youcheng Energy Saving Technology Co., Ltd. May 2017 Table of Contents 1 Significant Benefits Brought by the ASSV1.0 Control System……………………………2 2 Background of the Proposal and Need for the Project…………………………………2 3 Working Principle and System Composition of the ASSV1.0 Control System……………………………3 4 Contents of the Project Construction………………………………………………………7 5 System Configuration………………………………………………………………8 6 Advantages of the System……………………………………………………………9 7 Market Application Status…………………………………………………………11 1 Significant Benefits Brought by the ASSV1.0 Control System According to the data obtained from an on-site inspection of the compressors on May 13, 2017, the 4M32-13.82/24-186 new hydrogen compressors in the wax oil hydrogenation unit C1102A/B of Shandong Haihua Chemical Co., Ltd. have a designed flow rate of 17,360 Nm3/h; considering pressure variations during operation, the actual flow rate is around 16,000 Nm3/h. However, the actual operating flow rate is approximately 11,000 Nm3/h, which means that about 31% of the compression energy is wasted. 1.1 Advantages of equipping with the ASSV1.0 control system
1.1.1 It enables automatic, continuous, and rapid regulation within a load range of 60–100% according to the requirements of the main control variable ； 1.1.2 Automatic pressure control between different stages can be achieved based on the compression ratio, ensuring that the compressor operates in its optimal working condition at all times ； 1.1.3 Enables smooth loading of the compressor, shock-free switching, and shutdown ； 1.1.4 It can improve the operability of the compressor and help reduce friction in the moving mechanisms ； 1.1.5 Cooling the outer surface of the clearance cylinder enables the compressor to approach an isothermal compression process, thereby minimizing energy consumption ； 1.1.6 It has a significant reducing effect on compressors with high vibration levels. 1.2 Economic benefits brought by equipping the ASSV1.0 control system 1.2.1 With the ASSV1.0 variable clearance volume control system installed on this compressor, it is possible to save approximately 0.31*1600*8000 = 3.968 million kWh of electricity per year. This corresponds to around 396.8*0.70 = 2.7776 million yuan in monetary terms; thus, the investment cost can be recovered in a short period of time. 1.2.2 Energy savings and reduced consumption, high return on investment ； 1.2.3 The price is low, at around 30% of the cost of imported equipment ； 1.2.4 Low operating cost, with virtually no maintenance required. 2 Background of the proposal and necessity of the project: For the wax oil hydrogenation unit C1102A/B at Shandong Haihua Chemical Co., Ltd., the new hydrogen compressors of models 4M32-13, 82/24-186 are required; based on our on-site inspections, the designed flow rate for these compressors is approximately 16,000 Nm3/h. In actual operation, this unit requires approximately 11,000 Nm3/h of gas for production, which accounts for about 69% of the total gas volume needed. The shaft power of this unit still operates at full load, resulting in a waste of around 31% of the shaft power. Traditional methods for adjusting the air volume in reciprocating compressors include adjusting the intake valve, using a fixed clearance chamber, and bypass regulation. Among them, the adjustment of the poppet intake valve and the adjustment of the fixed clearance chamber are stepped adjustments, while the bypass adjustment is an energy-consuming adjustment. Currently, adjusting the intake valve by pushing it open during certain phases of the operation is a method that offers a large adjustment range and good energy-saving effects. This method enables stepless adjustment of air volume from 20% to 100%, but since there are precise requirements regarding the timing at which the intake valve is opened, it demands high standards for control and actuation mechanisms, resulting in high investment costs. Shandong Youcheng Energy Saving Technology Co., Ltd. has developed the ASSV1.0 variable air volume control system (hereinafter referred to as the ASSV1.0 control system) by utilizing the patented technology of the \"Variable clearance adjustment device for piston reciprocating compressors\". Without altering the original structure of the compressor or its control system, only the compressor cylinder head is modified, with the original fixed clearance end cover being removed. Through intelligent adjustment by the electro-hydraulic control mechanism, it can automatically control the flow rate to achieve continuous stepless regulation within 60%–100%, as well as adjust the compression ratio at various levels, based on the specified control parameters. It also enables smooth start-up, switching, and shutdown of the compressor, allowing for maintenance and repair of the control system in a short time without having to shut down the compressor. The ASSV1.0 control system adopts a mature and standard PLC-controlled electro-hydraulic control method, thereby enabling automatic control of the compressor’s air volume and the compression ratio at various stages. It features low investment and maintenance costs, high stability in air output, flexible parameter setting, and reliability. Since there is no excess air flowing in and out of the intake valve repeatedly, the resistance loss is low, which reduces the frequency of damage to the intake valve; moreover, its energy-saving performance is slightly better than that of some methods that use valve opening over a certain stroke for adjustment. In light of the above circumstances, we recommend installing the ASSV1.0 control system energy-saving equipment developed by our company on the 4M32-13 and 82/24-186 new hydrogen compressors of the wax oil hydrogenation unit C1102A/B at Shandong Haihua Chemical Co., Ltd. 3 Operation Principle and System Composition of the ASSV1.0 Control System 3.1 Operation Principle Figure 1 shows a schematic diagram of the compressor with a fixed clearance Vc, along with the p-V diagram of an ideal gas. In the graph, the horizontal axis V represents the change in cylinder volume, while the vertical axis P represents the change in cylinder pressure; P1 and P2 represent the intake and exhaust pressures respectively. In the diagram, 1—2—3—4 represents the cycle diagram for complete exhaust when there is a clearance volume Vc. Due to the presence of the clearance volume Vc, intake of gas begins only when the piston moves to the right to position 4, causing the gas volume in the cylinder to expand from Vc to V4 and the pressure to drop from P2 to P1. The length of the corresponding line segment for the air intake is 4–1; the compression process corresponds to 1–2, the exhaust process to 2–3, and the expansion process to 3–4. The area enclosed by 1—2—3—4—1 is the work required for one reciprocating stroke. Figure 2 shows a schematic diagram of the compressor with an additional clearance volume added to Vc, resulting in Vc′, along with the P-V diagram for an ideal gas. In the graph, the horizontal axis V represents the change in cylinder volume, while the vertical axis P represents the change in cylinder pressure; P1 and P2 represent the intake and exhaust pressures respectively. The length of the corresponding line segment for the air intake is 4′-1; the compression process corresponds to 1–2′, the exhaust process to 2′–3, and the expansion process to 3–4′. The area enclosed by 1—2′—3—4′—1 represents the work required for one complete cycle. When the clearance increases to Vc′, both the exhaust volume and the energy consumption required decrease. Adjustable clearance adjustment is a method that, based on fixed clearance adjustment, changes the fixed clearance to one where the clearance volume can be adjusted continuously. It eliminates the clearance end cover that controls the connection between the auxiliary clearance chamber and the cylinder; the adjustable clearance cylinder is in direct communication with the outer cylinder, resulting in almost no loss of pressure when gas enters or exits the adjustable clearance cylinder. As shown in Figure 3, which illustrates the schematic diagram and indicator diagram of adjustable clearance adjustment, when it is necessary to reduce the exhaust volume, the clearance volume can be increased to Vc′. In this case, the power cycle diagram becomes 1—2′—3—4′. The intake volume decreases from the length of line segment 4–1 corresponding to the total intake volume to the length of line segment 4′–1. The compression process occurs along the path 1–2′; the rate of increase in piston force during this compression process is lower than that when the clearance volume is Vc. The exhaust volume decreases from the length of line segment 2–3 corresponding to the total exhaust volume to the length of line segment 2′–3. Due to the absence of additional resistance, during the 3–4’ expansion cycle, the gas does work on the compressor piston, reducing the load on the crankshaft connecting rods. When zero exhaust volume from the outer cylinder is required, the clearance volume can be increased to Vc″. At this point, the high-pressure gas remaining in the clearance Vc″ expands until the intake stroke Vs ends, and the expansion line and the compression line merge into one, as shown by the process lines 1–3–3–4″ in Figure 3. As can be seen from the working principle of the adjustable clearance piston in the ASSV1.0 control system shown in Figure 4, for double-acting cylinders, by using relatively common electro-hydraulic control devices and controlling the position of the clearance piston, it is possible to achieve stepless adjustment of the compressor displacement within the range of 60% to 100%. The ASSV1.0 control system is a digital electro-hydraulic stepless capacity control system developed specifically for reciprocating compressors; it is suitable for compressors with radially arranged valves. The control system can, based on the set gas flow rate, specified values, or parameters entered manually, utilize an electro-hydraulic position control system composed of a PLC programmable controller, proportional valves, displacement sensors, and servo cylinders to cause the piston of the clearance cylinder to move linearly in response to the input signals. This enables servo control of the clearance volume at each stage, thereby allowing for control over the compressor’s exhaust volume and the compression ratio between stages. The actuator part of the cylinder features a venting function that prevents air leaks from entering the hydraulic oil system, as well as oil leaks from entering the compressor cylinders. Figure 4 shows the working principle of the adjustable clearance piston in the ASSV1.0 control system. As can be seen from Figure 5, which illustrates the basic components of the ASSV1.0 control system, a compressor with this control system consists mainly of an instrument control system, a hydraulic control system, cylinder actuators, as well as electrical and hydraulic pipelines. 3.2.1 Instrument Control System The instrument control system includes a PLC controller, an AD module for signal acquisition, and a signal display unit; it provides functions for processing signal exchange between the system itself and user systems. It serves as a bridge connecting the ASSV1.0 control system and the user’s DCS system, enabling automatic control based on the required process parameters such as pressure, flow rate, and temperature. 3.2.2 Hydraulic control system: The hydraulic oil station supplies high-pressure hydraulic oil to the actuators; through an internal gear oil pump, the pressure of this hydraulic oil is increased from atmospheric pressure to around 14 MPa (the exact pressure value depends on the highest inlet and outlet pressure levels under control in the compressor). A fuel station includes components such as an engine oil pump, solenoid valves, proportional valves, temperature relays, pressure transmitters, level switches, filters, and an oil tank. Figure 5: Basic composition diagram of the ASSV1.0 control system. Figure 3.2.3: Cylinder actuator. The actuator consists of a clearance cylinder, a hydraulic cylinder, a piston, and a displacement sensor. An electro-hydraulic control system made up of a PLC programmable controller, proportional valves, a displacement sensor, and a servo hydraulic cylinder is used to enable the piston of the clearance cylinder to move linearly in response to input signals, thereby achieving servo control over the changes in clearance volume at various stages. This, in turn, allows for control of the compressor’s exhaust volume and the compression ratio between different stages. 4. Content of project construction: The ASSV1.0 control system is designed for control valves that accept 4–20mA standard current signals, and it can be easily integrated into the user’s existing DCS control systems. The signals that typically need to be connected include the DCS control signals (4–20mA current signals) as well as the inlet and outlet pressures at various stages of the compressor. Under the monitoring of pressure sensors, the ASSV1.0 control system automatically adjusts the subsequent compression ratio based on the set compression ratio; it uses a PLC controller to calculate the drive values for the proportional valve in order to control the flow rate and pressure. The main components of the project to equip the compressor with an ASSV1.0 control system include: 4.1 Actuator section — To fulfill the control requirements, all the original end cover parts of the compressor are removed, and hydraulic clearance cylinder actuators are installed in their place. 4.2 Instrument section — The instruments include a PLC controller, analog-to-digital conversion unit, color LCD touch screen, switching power supply, and proportional valve driver; all of them are housed in the field instrument explosion-proof box. 4.3 Hydraulic unit section — The hydraulic system provides hydraulic power to the hydraulic actuators. It is integrated with the instrument control system section and can be directly placed on the floor next to the anti-vibration site compressor. Figure 6: On-site installation of the ASSV1.0 control system. 4.4 Installation – Jiujiang Daan Company provides all technical documentation related to the components of the ASSV1.0 control system, as well as relevant technical support, and is responsible for completing the system’s commissioning. As shown in Figure 6, the installation schematic of the ASSV1.0 control system mainly includes the following components: 4.4.1 Installing the clearance cylinders for each actuator; 4.4.2 Installing the hydraulic oil station; 4.4.3 Installing all hydraulic metal pipes and hoses; 4.4.4 Installing all cables for the control cabinets as well as external connection cables; 4.4.5 Installing displacement sensors and their cables. 5 System Configuration: Based on the structural characteristics of the compressors on site and the standard configuration scheme for the ASSV1.0 control system, the recommended scope of supply is listed in the table below: Actuators: Clearance cylinders – 45# brand, produced by Changzhou Tianyu; Displacement sensors – CHM0xxxMGR brand, produced by Beckhoff in Beijing; Seals and support rings – made of fluororubber, PTFE, or polyurethane, produced by Heliatek in the UK. Hydraulic oil station: Oil tank – made of 304 stainless steel, custom-made; Explosion-proof motor – YBxn3100L/3KW (specified), produced in Nanyang; Hydraulic circuit boards – made of alloy aluminum, custom-made; Electromagnetic directional valves – DSG-01-3C4/D24, produced by Oil Research; Pressure transmitters – 3051 model, produced by Rosemount; Relief valves – DBDH6K10/10Mpa, produced by Huade; Manual directional valves – SDF-02-01, custom-made; Accumulators – NXQ-25, produced in Fenghua; Precision filters – 5U-JFX-76H, produced by 707 Institute; Pressure gauges – DS63-D, produced by Wuhan Paixiang; Bimetallic temperature sensors – WSX-71, produced by Mingling Hydraulics; Level relays – YKJD24-300, produced by Mingling Hydraulics; Air filters – EF3-40, produced by Mingling Hydraulics; Hydraulic locks – YKF-02-02, custom-made; Level thermometers – YWZ-300T, produced by Mingling Hydraulics; Pump inlet filters – XU-63X80-J, produced by Mingling Hydraulics; Shut-off valves – JF-01-01, custom-made; Hydraulic pumps – ALP2A-D-16, produced by Mazuzzi in Italy. Control system: PLC – S7-200, produced by Siemens; Displays – 10″ color LCD touchscreens, produced by Kunlun Tongtai; AD modules – from Mitsubishi or Siemens; Wiring terminal blocks – JX--02--01, produced by Phoenix; Switching power supplies – SE-350, produced by Mean Well in Taiwan; Relays – from Omron; Power switches – Z8030, produced by Huarong; Explosion-proof instrument boxes – YX-01, produced by Huarong; Safety detection systems – from Daan; Pressure transmitters – AST, produced by Rosemount in the US; Shut-off valves – JF-01-01, custom-made; Pressure gauges – Y100BFZ, produced by Shanghai Yichuan; Pneumatic check valves – KA-15 (specified by SMC), produced by Xinyang Electromechanical; Pneumatic pressure reducers – QTY-8 (specified by SMC), produced by Leqing Shunyuan; Hydraulic pipes – made of 304 stainless steel, customized; Type of clearance cylinders – water-cooled. Scope of supply: Clearance cylinders, control cabinet systems, and cables connecting the clearance cylinders to the control cabinets are provided; however, cables connecting the control cabinets to the control room and power cables are not included. Scope of service: No responsibility for the installation of clearance cylinders on-site or for the wiring of electrical instruments; responsible only for providing on-site guidance for installation, commissioning, and training. Note: All the above configurations are in accordance with the factory-standard specifications. Advantages of the 6-system: The advantages of using the ASSV1.0 control system are mainly reflected in the following aspects. 6.1 System Operability: After being equipped with the ASSV1.0 control system, the compressor can have its load automatically adjusted between 60% and 100% through hydraulic manual control, on-site automatic control, or DCS control. Adjusting the compressor’s air volume is simplified to merely changing the clearance position of the actuator’s primary cylinder; the system then automatically tracks and adjusts the pressure value at the subsequent stage. After use, it makes the control of the compressor more rational, enabling smooth loading, shock-free switching, and shutdown of the compressor. 6.2 System safety The ASSV1.0 control system utilizes relatively common electro-hydraulic controls and actuators, and features a position locking control function to ensure that the load remains stable without any fluctuations. The control system also features a manual adjustment function; in the event of a failure in the instrument control unit, a manual directional valve can be used to control the amount of clearance, ensuring the reliable operation of the compressor. The actuator is equipped with vent ports to ensure that any leaked gas does not enter the hydraulic oil system, and any oil leakage does not enter the compressor cylinders. When the leakage exceeds the set value, an alarm or a high-alarm signal is issued; when the leakage reaches the high-alarm level, the control system shuts down the oil pump and increases the clearance to ensure that the compressor continues to operate. 6.3 System Reliability: The main components of the ASSV1.0 control system are from well-known foreign manufacturers; its excellent and rigorous design and manufacturing ensure high reliability for this product. Since its introduction in 2008, the units that have been used have been operating properly to this day, with immediate energy-saving effects. Due to its advantages such as low cost, safety and reliability, simple installation, and low maintenance requirements, it is gradually replacing imported equipment. 6.4 Key specifications of the energy-efficient compressor in the system: Shaft power (Kw): 1600 (motor: 1800). Suction pressure at each stage (MPa): 2.4/5.16/10.13; Suction pressure at each stage (MPa): 5.16/10.13/18.7; Suction temperature at each stage (°C): 40/40/40; Exhaust temperature at each stage (°C): 118/110/103. Operational parameters: Flow rate (Nm3/h): 11000. Suction pressure at each stage (MPa): 2.2/4.625/8.8; Suction pressure at each stage (MPa): 4.6/8.7/15.6. Based on the actual demand, the volume of compressed air required is approximately 69% of the designed amount. With the current bypass control system in place, about 31% of the compression energy is wasted, and a large amount of cooling water is also wasted to cool the compressed, high-pressure, high-temperature gas returning back. By adopting the ASSV1.0 variable air volume system with stepless clearance adjustment, which currently offers the best energy-saving effects, it is possible to save a large amount of electricity and water, resulting in significant economic benefits. Preliminary calculations show that, based on 31% of the actual output flow, the shaft power can be reduced by approximately 496 kW. Assuming 8,000 hours of operation per year, this results in an annual energy savings of around 3.968 million kWh. At an electricity price of 0.70 yuan per kWh, the annual cost savings amount to approximately 2.7776 million yuan. Now, we estimate the energy-saving effects of this compressor after being equipped with ASSV1.0 under different load conditions, as shown in the table below: Compressor load (%) 100 90 80 70 71 60 Shaft power (KW) 1600 1440 1280 1120 1104 960 Reduced shaft power (KW) 0 160 320 480 496 640 Electricity cost savings (10,000 RMB) 0 89.6 179.2 268.8 277.76 358.4 Considering the actual operating conditions of this compressor, a 31% reduction in shaft power is anticipated. This would result in annual electricity cost savings of approximately 2.7776 million RMB. The investment cost for using this equipment can thus be recovered in a short period of time. We will still design the adjustable clearance volume at 60%, and the volume of the actuator cylinders at each stage will also be calculated based on this value. The above are the results of theoretical calculations. After equipping this machine with a clearance adjustment system, and taking into account various factors such as the production volume of compressors on site, pressure fluctuations, valve leakage, and motor power losses, we have set a target of 69% of the shaft power as the budget figure; it is feasible to achieve annual electricity cost savings of over 2.7776 million yuan. Considering a more conservative compressor design as well as operation under conditions of high nonlinear compression ratios, our clearance adjustment range is 60–100%. Based on the actual usage patterns of clearance adjustment in various multi-stage compressors in existing plants, we have designed the compressors for your company using a three-stage, three-clearance cylinder configuration to provide you with the optimal design solution. 7 Market application Since its promotion in 2008, the ASSV1.0 control system has been installed on compressors used in numerous petrochemical enterprises, including Sinopec, PetroChina, CNOOC, and various local oil refineries. Its main users include Sinopec Jingmen Branch, Sinopec Zhanjiang Dongxing Petrochemical, PetroChina Jinxi Branch, Sinopec Tianjin Branch, Sinopec Zhongyuan Oilfield Branch, Qilu Petrochemical, Shandong Huifeng Petrochemical, Shandong Changyi Petrochemical, and Shandong Jingbo Chemical, among others. The energy-saving effects of this system are quite remarkable. For enterprises that consume large amounts of electricity, choosing our company’s ASSV1.0 control system—a highly efficient and energy-saving product—can not only help them **reduce unnecessary electricity costs, but also enable them to **make their due contributions toward energy conservation and emission reduction. Finally, we welcome the leaders and experts from Shandong Haihua Chemical Co., Ltd. to our company for an inspection and guidance, and we encourage them to choose our ASSV1.0 variable air volume control system! Thank you for reviewing! Please provide your valuable feedback!
1.1.1 It enables automatic, continuous, and rapid regulation within a load range of 60–100% according to the requirements of the main control variable ； 1.1.2 Automatic pressure control between different stages can be achieved based on the compression ratio, ensuring that the compressor operates in its optimal working condition at all times ； 1.1.3 Enables smooth loading of the compressor, shock-free switching, and shutdown ； 1.1.4 It can improve the operability of the compressor and help reduce friction in the moving mechanisms ； 1.1.5 Cooling the outer surface of the clearance cylinder enables the compressor to approach an isothermal compression process, thereby minimizing energy consumption ； 1.1.6 It has a significant reducing effect on compressors with high vibration levels. 1.2 Economic benefits brought by equipping the ASSV1.0 control system 1.2.1 With the ASSV1.0 variable clearance volume control system installed on this compressor, it is possible to save approximately 0.31*1600*8000 = 3.968 million kWh of electricity per year. This corresponds to around 396.8*0.70 = 2.7776 million yuan in monetary terms; thus, the investment cost can be recovered in a short period of time. 1.2.2 Energy savings and reduced consumption, high return on investment ； 1.2.3 The price is low, at around 30% of the cost of imported equipment ； 1.2.4 Low operating cost, with virtually no maintenance required. 2 Background of the proposal and necessity of the project: For the wax oil hydrogenation unit C1102A/B at Shandong Haihua Chemical Co., Ltd., the new hydrogen compressors of models 4M32-13, 82/24-186 are required; based on our on-site inspections, the designed flow rate for these compressors is approximately 16,000 Nm3/h. In actual operation, this unit requires approximately 11,000 Nm3/h of gas for production, which accounts for about 69% of the total gas volume needed. The shaft power of this unit still operates at full load, resulting in a waste of around 31% of the shaft power. Traditional methods for adjusting the air volume in reciprocating compressors include adjusting the intake valve, using a fixed clearance chamber, and bypass regulation. Among them, the adjustment of the poppet intake valve and the adjustment of the fixed clearance chamber are stepped adjustments, while the bypass adjustment is an energy-consuming adjustment. Currently, adjusting the intake valve by pushing it open during certain phases of the operation is a method that offers a large adjustment range and good energy-saving effects. This method enables stepless adjustment of air volume from 20% to 100%, but since there are precise requirements regarding the timing at which the intake valve is opened, it demands high standards for control and actuation mechanisms, resulting in high investment costs. Shandong Youcheng Energy Saving Technology Co., Ltd. has developed the ASSV1.0 variable air volume control system (hereinafter referred to as the ASSV1.0 control system) by utilizing the patented technology of the \"Variable clearance adjustment device for piston reciprocating compressors\". Without altering the original structure of the compressor or its control system, only the compressor cylinder head is modified, with the original fixed clearance end cover being removed. Through intelligent adjustment by the electro-hydraulic control mechanism, it can automatically control the flow rate to achieve continuous stepless regulation within 60%–100%, as well as adjust the compression ratio at various levels, based on the specified control parameters. It also enables smooth start-up, switching, and shutdown of the compressor, allowing for maintenance and repair of the control system in a short time without having to shut down the compressor. The ASSV1.0 control system adopts a mature and standard PLC-controlled electro-hydraulic control method, thereby enabling automatic control of the compressor’s air volume and the compression ratio at various stages. It features low investment and maintenance costs, high stability in air output, flexible parameter setting, and reliability. Since there is no excess air flowing in and out of the intake valve repeatedly, the resistance loss is low, which reduces the frequency of damage to the intake valve; moreover, its energy-saving performance is slightly better than that of some methods that use valve opening over a certain stroke for adjustment. In light of the above circumstances, we recommend installing the ASSV1.0 control system energy-saving equipment developed by our company on the 4M32-13 and 82/24-186 new hydrogen compressors of the wax oil hydrogenation unit C1102A/B at Shandong Haihua Chemical Co., Ltd. 3 Operation Principle and System Composition of the ASSV1.0 Control System 3.1 Operation Principle Figure 1 shows a schematic diagram of the compressor with a fixed clearance Vc, along with the p-V diagram of an ideal gas. In the graph, the horizontal axis V represents the change in cylinder volume, while the vertical axis P represents the change in cylinder pressure; P1 and P2 represent the intake and exhaust pressures respectively. In the diagram, 1—2—3—4 represents the cycle diagram for complete exhaust when there is a clearance volume Vc. Due to the presence of the clearance volume Vc, intake of gas begins only when the piston moves to the right to position 4, causing the gas volume in the cylinder to expand from Vc to V4 and the pressure to drop from P2 to P1. The length of the corresponding line segment for the air intake is 4–1; the compression process corresponds to 1–2, the exhaust process to 2–3, and the expansion process to 3–4. The area enclosed by 1—2—3—4—1 is the work required for one reciprocating stroke. Figure 2 shows a schematic diagram of the compressor with an additional clearance volume added to Vc, resulting in Vc′, along with the P-V diagram for an ideal gas. In the graph, the horizontal axis V represents the change in cylinder volume, while the vertical axis P represents the change in cylinder pressure; P1 and P2 represent the intake and exhaust pressures respectively. The length of the corresponding line segment for the air intake is 4′-1; the compression process corresponds to 1–2′, the exhaust process to 2′–3, and the expansion process to 3–4′. The area enclosed by 1—2′—3—4′—1 represents the work required for one complete cycle. When the clearance increases to Vc′, both the exhaust volume and the energy consumption required decrease. Adjustable clearance adjustment is a method that, based on fixed clearance adjustment, changes the fixed clearance to one where the clearance volume can be adjusted continuously. It eliminates the clearance end cover that controls the connection between the auxiliary clearance chamber and the cylinder; the adjustable clearance cylinder is in direct communication with the outer cylinder, resulting in almost no loss of pressure when gas enters or exits the adjustable clearance cylinder. As shown in Figure 3, which illustrates the schematic diagram and indicator diagram of adjustable clearance adjustment, when it is necessary to reduce the exhaust volume, the clearance volume can be increased to Vc′. In this case, the power cycle diagram becomes 1—2′—3—4′. The intake volume decreases from the length of line segment 4–1 corresponding to the total intake volume to the length of line segment 4′–1. The compression process occurs along the path 1–2′; the rate of increase in piston force during this compression process is lower than that when the clearance volume is Vc. The exhaust volume decreases from the length of line segment 2–3 corresponding to the total exhaust volume to the length of line segment 2′–3. Due to the absence of additional resistance, during the 3–4’ expansion cycle, the gas does work on the compressor piston, reducing the load on the crankshaft connecting rods. When zero exhaust volume from the outer cylinder is required, the clearance volume can be increased to Vc″. At this point, the high-pressure gas remaining in the clearance Vc″ expands until the intake stroke Vs ends, and the expansion line and the compression line merge into one, as shown by the process lines 1–3–3–4″ in Figure 3. As can be seen from the working principle of the adjustable clearance piston in the ASSV1.0 control system shown in Figure 4, for double-acting cylinders, by using relatively common electro-hydraulic control devices and controlling the position of the clearance piston, it is possible to achieve stepless adjustment of the compressor displacement within the range of 60% to 100%. The ASSV1.0 control system is a digital electro-hydraulic stepless capacity control system developed specifically for reciprocating compressors; it is suitable for compressors with radially arranged valves. The control system can, based on the set gas flow rate, specified values, or parameters entered manually, utilize an electro-hydraulic position control system composed of a PLC programmable controller, proportional valves, displacement sensors, and servo cylinders to cause the piston of the clearance cylinder to move linearly in response to the input signals. This enables servo control of the clearance volume at each stage, thereby allowing for control over the compressor’s exhaust volume and the compression ratio between stages. The actuator part of the cylinder features a venting function that prevents air leaks from entering the hydraulic oil system, as well as oil leaks from entering the compressor cylinders. Figure 4 shows the working principle of the adjustable clearance piston in the ASSV1.0 control system. As can be seen from Figure 5, which illustrates the basic components of the ASSV1.0 control system, a compressor with this control system consists mainly of an instrument control system, a hydraulic control system, cylinder actuators, as well as electrical and hydraulic pipelines. 3.2.1 Instrument Control System The instrument control system includes a PLC controller, an AD module for signal acquisition, and a signal display unit; it provides functions for processing signal exchange between the system itself and user systems. It serves as a bridge connecting the ASSV1.0 control system and the user’s DCS system, enabling automatic control based on the required process parameters such as pressure, flow rate, and temperature. 3.2.2 Hydraulic control system: The hydraulic oil station supplies high-pressure hydraulic oil to the actuators; through an internal gear oil pump, the pressure of this hydraulic oil is increased from atmospheric pressure to around 14 MPa (the exact pressure value depends on the highest inlet and outlet pressure levels under control in the compressor). A fuel station includes components such as an engine oil pump, solenoid valves, proportional valves, temperature relays, pressure transmitters, level switches, filters, and an oil tank. Figure 5: Basic composition diagram of the ASSV1.0 control system. Figure 3.2.3: Cylinder actuator. The actuator consists of a clearance cylinder, a hydraulic cylinder, a piston, and a displacement sensor. An electro-hydraulic control system made up of a PLC programmable controller, proportional valves, a displacement sensor, and a servo hydraulic cylinder is used to enable the piston of the clearance cylinder to move linearly in response to input signals, thereby achieving servo control over the changes in clearance volume at various stages. This, in turn, allows for control of the compressor’s exhaust volume and the compression ratio between different stages. 4. Content of project construction: The ASSV1.0 control system is designed for control valves that accept 4–20mA standard current signals, and it can be easily integrated into the user’s existing DCS control systems. The signals that typically need to be connected include the DCS control signals (4–20mA current signals) as well as the inlet and outlet pressures at various stages of the compressor. Under the monitoring of pressure sensors, the ASSV1.0 control system automatically adjusts the subsequent compression ratio based on the set compression ratio; it uses a PLC controller to calculate the drive values for the proportional valve in order to control the flow rate and pressure. The main components of the project to equip the compressor with an ASSV1.0 control system include: 4.1 Actuator section — To fulfill the control requirements, all the original end cover parts of the compressor are removed, and hydraulic clearance cylinder actuators are installed in their place. 4.2 Instrument section — The instruments include a PLC controller, analog-to-digital conversion unit, color LCD touch screen, switching power supply, and proportional valve driver; all of them are housed in the field instrument explosion-proof box. 4.3 Hydraulic unit section — The hydraulic system provides hydraulic power to the hydraulic actuators. It is integrated with the instrument control system section and can be directly placed on the floor next to the anti-vibration site compressor. Figure 6: On-site installation of the ASSV1.0 control system. 4.4 Installation – Jiujiang Daan Company provides all technical documentation related to the components of the ASSV1.0 control system, as well as relevant technical support, and is responsible for completing the system’s commissioning. As shown in Figure 6, the installation schematic of the ASSV1.0 control system mainly includes the following components: 4.4.1 Installing the clearance cylinders for each actuator; 4.4.2 Installing the hydraulic oil station; 4.4.3 Installing all hydraulic metal pipes and hoses; 4.4.4 Installing all cables for the control cabinets as well as external connection cables; 4.4.5 Installing displacement sensors and their cables. 5 System Configuration: Based on the structural characteristics of the compressors on site and the standard configuration scheme for the ASSV1.0 control system, the recommended scope of supply is listed in the table below: Actuators: Clearance cylinders – 45# brand, produced by Changzhou Tianyu; Displacement sensors – CHM0xxxMGR brand, produced by Beckhoff in Beijing; Seals and support rings – made of fluororubber, PTFE, or polyurethane, produced by Heliatek in the UK. Hydraulic oil station: Oil tank – made of 304 stainless steel, custom-made; Explosion-proof motor – YBxn3100L/3KW (specified), produced in Nanyang; Hydraulic circuit boards – made of alloy aluminum, custom-made; Electromagnetic directional valves – DSG-01-3C4/D24, produced by Oil Research; Pressure transmitters – 3051 model, produced by Rosemount; Relief valves – DBDH6K10/10Mpa, produced by Huade; Manual directional valves – SDF-02-01, custom-made; Accumulators – NXQ-25, produced in Fenghua; Precision filters – 5U-JFX-76H, produced by 707 Institute; Pressure gauges – DS63-D, produced by Wuhan Paixiang; Bimetallic temperature sensors – WSX-71, produced by Mingling Hydraulics; Level relays – YKJD24-300, produced by Mingling Hydraulics; Air filters – EF3-40, produced by Mingling Hydraulics; Hydraulic locks – YKF-02-02, custom-made; Level thermometers – YWZ-300T, produced by Mingling Hydraulics; Pump inlet filters – XU-63X80-J, produced by Mingling Hydraulics; Shut-off valves – JF-01-01, custom-made; Hydraulic pumps – ALP2A-D-16, produced by Mazuzzi in Italy. Control system: PLC – S7-200, produced by Siemens; Displays – 10″ color LCD touchscreens, produced by Kunlun Tongtai; AD modules – from Mitsubishi or Siemens; Wiring terminal blocks – JX--02--01, produced by Phoenix; Switching power supplies – SE-350, produced by Mean Well in Taiwan; Relays – from Omron; Power switches – Z8030, produced by Huarong; Explosion-proof instrument boxes – YX-01, produced by Huarong; Safety detection systems – from Daan; Pressure transmitters – AST, produced by Rosemount in the US; Shut-off valves – JF-01-01, custom-made; Pressure gauges – Y100BFZ, produced by Shanghai Yichuan; Pneumatic check valves – KA-15 (specified by SMC), produced by Xinyang Electromechanical; Pneumatic pressure reducers – QTY-8 (specified by SMC), produced by Leqing Shunyuan; Hydraulic pipes – made of 304 stainless steel, customized; Type of clearance cylinders – water-cooled. Scope of supply: Clearance cylinders, control cabinet systems, and cables connecting the clearance cylinders to the control cabinets are provided; however, cables connecting the control cabinets to the control room and power cables are not included. Scope of service: No responsibility for the installation of clearance cylinders on-site or for the wiring of electrical instruments; responsible only for providing on-site guidance for installation, commissioning, and training. Note: All the above configurations are in accordance with the factory-standard specifications. Advantages of the 6-system: The advantages of using the ASSV1.0 control system are mainly reflected in the following aspects. 6.1 System Operability: After being equipped with the ASSV1.0 control system, the compressor can have its load automatically adjusted between 60% and 100% through hydraulic manual control, on-site automatic control, or DCS control. Adjusting the compressor’s air volume is simplified to merely changing the clearance position of the actuator’s primary cylinder; the system then automatically tracks and adjusts the pressure value at the subsequent stage. After use, it makes the control of the compressor more rational, enabling smooth loading, shock-free switching, and shutdown of the compressor. 6.2 System safety The ASSV1.0 control system utilizes relatively common electro-hydraulic controls and actuators, and features a position locking control function to ensure that the load remains stable without any fluctuations. The control system also features a manual adjustment function; in the event of a failure in the instrument control unit, a manual directional valve can be used to control the amount of clearance, ensuring the reliable operation of the compressor. The actuator is equipped with vent ports to ensure that any leaked gas does not enter the hydraulic oil system, and any oil leakage does not enter the compressor cylinders. When the leakage exceeds the set value, an alarm or a high-alarm signal is issued; when the leakage reaches the high-alarm level, the control system shuts down the oil pump and increases the clearance to ensure that the compressor continues to operate. 6.3 System Reliability: The main components of the ASSV1.0 control system are from well-known foreign manufacturers; its excellent and rigorous design and manufacturing ensure high reliability for this product. Since its introduction in 2008, the units that have been used have been operating properly to this day, with immediate energy-saving effects. Due to its advantages such as low cost, safety and reliability, simple installation, and low maintenance requirements, it is gradually replacing imported equipment. 6.4 Key specifications of the energy-efficient compressor in the system: Shaft power (Kw): 1600 (motor: 1800). Suction pressure at each stage (MPa): 2.4/5.16/10.13; Suction pressure at each stage (MPa): 5.16/10.13/18.7; Suction temperature at each stage (°C): 40/40/40; Exhaust temperature at each stage (°C): 118/110/103. Operational parameters: Flow rate (Nm3/h): 11000. Suction pressure at each stage (MPa): 2.2/4.625/8.8; Suction pressure at each stage (MPa): 4.6/8.7/15.6. Based on the actual demand, the volume of compressed air required is approximately 69% of the designed amount. With the current bypass control system in place, about 31% of the compression energy is wasted, and a large amount of cooling water is also wasted to cool the compressed, high-pressure, high-temperature gas returning back. By adopting the ASSV1.0 variable air volume system with stepless clearance adjustment, which currently offers the best energy-saving effects, it is possible to save a large amount of electricity and water, resulting in significant economic benefits. Preliminary calculations show that, based on 31% of the actual output flow, the shaft power can be reduced by approximately 496 kW. Assuming 8,000 hours of operation per year, this results in an annual energy savings of around 3.968 million kWh. At an electricity price of 0.70 yuan per kWh, the annual cost savings amount to approximately 2.7776 million yuan. Now, we estimate the energy-saving effects of this compressor after being equipped with ASSV1.0 under different load conditions, as shown in the table below: Compressor load (%) 100 90 80 70 71 60 Shaft power (KW) 1600 1440 1280 1120 1104 960 Reduced shaft power (KW) 0 160 320 480 496 640 Electricity cost savings (10,000 RMB) 0 89.6 179.2 268.8 277.76 358.4 Considering the actual operating conditions of this compressor, a 31% reduction in shaft power is anticipated. This would result in annual electricity cost savings of approximately 2.7776 million RMB. The investment cost for using this equipment can thus be recovered in a short period of time. We will still design the adjustable clearance volume at 60%, and the volume of the actuator cylinders at each stage will also be calculated based on this value. The above are the results of theoretical calculations. After equipping this machine with a clearance adjustment system, and taking into account various factors such as the production volume of compressors on site, pressure fluctuations, valve leakage, and motor power losses, we have set a target of 69% of the shaft power as the budget figure; it is feasible to achieve annual electricity cost savings of over 2.7776 million yuan. Considering a more conservative compressor design as well as operation under conditions of high nonlinear compression ratios, our clearance adjustment range is 60–100%. Based on the actual usage patterns of clearance adjustment in various multi-stage compressors in existing plants, we have designed the compressors for your company using a three-stage, three-clearance cylinder configuration to provide you with the optimal design solution. 7 Market application Since its promotion in 2008, the ASSV1.0 control system has been installed on compressors used in numerous petrochemical enterprises, including Sinopec, PetroChina, CNOOC, and various local oil refineries. Its main users include Sinopec Jingmen Branch, Sinopec Zhanjiang Dongxing Petrochemical, PetroChina Jinxi Branch, Sinopec Tianjin Branch, Sinopec Zhongyuan Oilfield Branch, Qilu Petrochemical, Shandong Huifeng Petrochemical, Shandong Changyi Petrochemical, and Shandong Jingbo Chemical, among others. The energy-saving effects of this system are quite remarkable. For enterprises that consume large amounts of electricity, choosing our company’s ASSV1.0 control system—a highly efficient and energy-saving product—can not only help them **reduce unnecessary electricity costs, but also enable them to **make their due contributions toward energy conservation and emission reduction. Finally, we welcome the leaders and experts from Shandong Haihua Chemical Co., Ltd. to our company for an inspection and guidance, and we encourage them to choose our ASSV1.0 variable air volume control system! Thank you for reviewing! Please provide your valuable feedback!