Question: Exam questions on dry quenching of coke

Dry Quenching of Coke Training Exam (3) Team: Name: Score: I. Fill-in-the-blank questions (3 points per blank, 60 points in total) 1. The fixed drainage device consists of: (boiler fixed drainage), (water wall fixed drainage), (light tube fixed drainage), and (finned fixed drainage). 2. The rotation speed of the coke drum is: (6 – 9 rev/min) ； The lifting speed of the elevator is: (4 r/min), (10 r/min), (30 r/min) ； Travel speed: (3.5 m/min, 4 m/min) ； The operation modes are: (on-site momentary), (on-site sequential), (central automatic). 3. The three pneumatic valves of the dry quenching furnace are: (pre-storage chamber pressure regulation), (air introduction), and (pre-storage chamber return) ； The working pressure is: (0.5 MPa). 4. Rotational speed of the rotary seal valve: (5 r/min) ； Available shaft seal gases: (N2), (compressed air) ； The pressure is: (10 MPa). II. Short-answer questions (10 points per question, 40 points in total) 1. Control of combustible gas components within the system? (10 points) Answer: To maintain stability in the composition of the gases within the system, to ensure that all combustible components are completely burned, and to prevent accidents, it is necessary to adjust the amount of air introduced and the amount of nitrogen supplied to the system in a timely manner. 1. When the temperature of the gas entering the boiler is greater than 600°C and less than 930°C, air should be introduced to reduce the combustible components in the system. 2. When the temperature of the gas entering the boiler is less than 600°C or greater than 930°C, it is necessary to temporarily remove some of the circulating gas and introduce nitrogen in order to adjust the level of combustible components within the system. 3. When the combustible components in the system rise abnormally and cannot be reduced by introducing air, nitrogen should be introduced to adjust the level of combustible components in the system. 2. Regulation of the boiler inlet temperature? (10 points) Answer: The level of the boiler inlet temperature is primarily determined by the amount of coke dried in this way and the volume of circulating air. With the circulation air volume in the dry quenching process remaining unchanged, an increase in the amount of coke dried will raise the boiler inlet temperature. During operation, it is necessary to determine an appropriate ratio of gas (circulating gas) to coke (amount of dry quenched coke). The volume of circulating air must be adjusted based on the coke pushing schedule of the coke oven and the operating conditions of the dry quenching equipment, so that the temperature at the boiler inlet remains within the normal range and the steam production and quality can be maintained stably. It should be noted that when the boiler inlet temperature is higher than the set value, the OCC system triggers an alarm, and the coke discharge from the dry quenching furnace stops automatically (interlock) ； Once the boiler inlet temperature returns to normal, resume coke discharge. 3. How to start and stop the circulating fan? (10 points) Answer: Startup procedure for the circulating fan: 1. Contact the electrical staff to supply power, and conduct on-site as well as central \"air drop\" tests. 2. During on-site startup, switch the toggle switch in the on-site control box of the fan and inlet control valve to “On-site”; during centralized control, switch the toggle switch in the on-site control box to “Central”, then press the start button to initiate the circulation fan. 3. After confirming that the motor current reading is normal, contact the control room and, under its guidance, gradually open the fan inlet control valve to adjust the volume of circulating air so that it matches the amount of coke being processed. 4. Report the fan startup status to the plant dispatch center. 5. After startup, check whether all components are operating properly, and closely monitor the bearing temperature as well as the current and vibration levels of the circulation fan. 6. Set the purge nitrogen solenoid valve for the circulating gas pipeline to the “automatic” operating mode. 7. After the dry quenching of coke is adjusted properly, activate the interlock for the fan. Shutdown procedure for the circulating fan: 1. Check whether the nitrogen solenoid valve used for purging the circulating gas pipeline is in the “automatic” mode. 2. Gradually adjust the fan inlet flow control valve to reduce the amount of circulating air. 3. Contact the central operator to confirm the circulating air volume and changes in motor current. 4. Gradually reduce the flow control valve at the fan inlet to prevent the fan from surging. 5. Transmit the information about the shutdown of the circulating fan to the plant controller and the coke oven shift leader. 6. Press the “Stop” button for the fan on the local control panel; the “Stop” light will turn on. 7. The circulation fan stops operating. 8. Check whether the N2 solenoid valves at the front and back of the fan as well as those in the air intake pipe open automatically to fill the system with N2. If nitrogen is not being introduced, change the operation mode of the solenoid valve for nitrogen purging on the display screen in the control room to “manual”, and then open the solenoid valve to fill the system with nitrogen. 4. What are the items checked during routine inspections? (10 points) Answer: 1. Maintain the equipment in accordance with the equipment maintenance procedures. 2. Check the operating condition of each device. 3. Check the cooling water supply for each water pump, fan, hydraulic coupler, water seal, gamma-ray level gauge, radiation pyrometer, and gas analyzer, and verify that all cooling water pipelines are unobstructed. 4. Check the nitrogen supply to the circulation fan and rotary seal valve, as well as whether the nitrogen pressure remains stable after pressure reduction. 5. Check the circulating gas system for any air leakage. 6. Regularly measure the dimensions of the compensators in various parts of the circulating gas system, and conduct comparative analysis. 7. Check the compensators in the circulating gas system for any damage or leaks. 8. Check the lubrication of key equipment such as the elevator drum, loading device, and rotary seal valve, and refill the oil tank regularly. 9. Assist laboratory technicians in sampling and analyzing the dust content in circulating gas using common exhaust pipes. 10. Check the particle size of the coke powder collected by the primary and secondary dust collectors (inspect using a scraper conveyor). 11. Conduct nitrogen injection tests to open the solenoid valves once a week in conjunction with the electrical maintenance staff.

Dry Quenching of Coke Training Exam (1) Team: Name: Score: I. Fill-in-the-blank questions (5 points per question, 30 points in total) 1. The main equipment for dry quenching of coke includes: (electric locomotives), (coke carriages), (APS units), (elevators), (circulation fans), (loading devices), (dry quenching furnaces), (boilers), etc. 2. The rated current of the deaeration circulation pump is (166.1) A, and its rotation speed is (2970 r/min) ； The rated current of the boiler feed water pump is (28.7) A, and its rotational speed is (2975 r/min). 3. The sampler is used to test four types of samples: (boiler feed water), (turbine feed water), (saturated steam), and (superheated steam). 4. The operating pressure of the safety valve in the deaeration tank is (0.1) Pa, the operating pressure of the deaeration head is (0.1) Pa, and the operating pressure of the low-pressure steam used for deaeration is (0.462) Pa. 5. The set pressure of the safety valve for control in the steam drum is (5.05) Pa, and its operating set pressure is (5.15) Pa ； The boiler model is (Q192/920-77-3.82/450). 6. The main raw materials and energy consumed in the dry quenching system include (coke), (nitrogen), (deionized water), (industrial water), (electricity), (compressed air), (steam), (coke oven gas), sodium phosphate, and propane. II. Short-answer questions (5 points each, 20 points in total) 1. What is the basic principle of dry quenching technology? Answer: Dry quenching of coke involves using inert gases (mainly nitrogen) to extinguish the red coke produced in coke ovens within a dry quenching furnace. After absorbing heat, these inert gases enter a boiler where they exchange heat with deionized water to generate medium-pressure steam. The inert gases are recycled through circulation fans, and the coke that has been dried quenched is transported to subsequent processing stages via a coke discharge system. The steam produced is used for power generation or heating. 2. What is the operation procedure for starting and stopping the deaerated feed water pump? Answer: Starting of the deaeration feed water pump: 1. Adjust the cooling water volume and check that the bearing oil ring rotates properly. 2. Press the “Start” button, and the ammeter will return to normal within 10 seconds. 3. Once the motor reaches its rated speed (after stable operation), slowly open the valve that allows the deaeration feed water pump to return water to the desalination tank, while paying attention to pressure changes. 4. Once the pump is running stably, open the pump’s outlet valve. 5. Adjust the opening of the deaerator level control valve and observe the changes in the deaerator level. 6. Check and measure the vibration of the water pump, motor, and bearings, and listen to each component. 7. After the water pump is operating normally, activate the interlock switch. 8. Record the start time. Shutting down the deaeration feed water pump: 1. Close the pump outlet valve and the valve leading back to the desalination tank. 2. Press the “Stop” button. 3. If the water pump is used as a standby pump, the outlet valve of the pump should be opened, and cooling water should continue to be supplied to activate the pump in interlocked operation. 4. If the water pump needs to be repaired after stopping, the pump outlet valve, inlet valve, and drain valve should be closed first, followed by turning off the cooling water, and then contacting the electrical staff to cut off the power supply. 5. Record the stop time and reason. 3. What are the test parameters and data for the feed water? Answer: PH: 8.5 — 9.2 ； Hardness: ≤0.003 mmol/L ； Dissolved oxygen: <15 μg/L ； Conductivity: <0.2 μs/cm 4. To increase the pressure after the low-pressure steam pressure reducing valve, what adjustments need to be made to the valve body? Answer: Loosen the fixing nut of the valve body adjustment bolt, turn the adjustment bolt clockwise until the desired pressure is reached, then lock the nut. III. Drawing Questions (Total 50 points) 1. Diagram of gas circulation in dry quenching of coke: (20 points) 2. Diagram of the pump room and boiler pump system: (30 points)

Advanced Level I: True or False Questions: (×) 1. Cleaning a newly installed boiler before it starts operating has no impact on future production. (×) 2. The liquid level in the boiler drum should be maintained between 0 and 100. (×) 3. The quality of the steam generated by the boiler depends entirely on the quality of the boiler water. (×) 4. The feed water for the dry quenching boiler can be supplied with deoxygenated desalinated water in a short period of time. (√) 5. The dust content at the dust removal inlet (under standard conditions) is less than 10 g/m3. (×) 6. In dry quenching of coke, the gas-to-coke ratio should be as high as possible, as this helps to reduce the coke discharge temperature. (×) 7. The shorter the dry quenching time of coke in the dry quenching furnace, the better. (√) 8. The automatic alignment device is mainly composed of a hydraulic station and hydraulic cylinders. (×) 9. Before shutting down the boiler for routine maintenance, the inlet temperature of the boiler must be reduced to below 500°C as specified. (×) 10. Leakage in the positive-pressure section of dry quenching mainly refers to the leakage between the fan outlet and the inlet of the primary dust removal system. (×) 11. Leakage in the positive-pressure section of dry quenching mainly refers to the leakage between the fan outlet and the inlet of the primary dust removal system. (√) 12. The upper limit of the drum’s liquid level is at 150 mm along the centerline of the drum. (√) 13. The limitation on the oxygen content in the boiler feedwater is primarily aimed at protecting the economizer. (×)14. The lower the steam temperature at the outlet of the dry quenching coke waste heat boiler, the better. (√) 15. The better the tightness of the dry quenching device, the greater its production capacity. (×)16. After the circulating gas automatic analyzer fails, for safety reasons, the amount of air introduced should be reduced. (×) 17. When switching pumps during normal operation, the pump that is currently in use should be stopped first, before starting the backup pump. (√) 18. The red coke in the pre-storage chamber of the dry quenching furnace does not undergo heat exchange with the circulating gas. (×) 19. During warm air drying, to raise the temperature of the circulating gas, the amount of air introduced should be reduced. (×) 20. When adjusting the opening area of the annular flue, the opening of the adjustment hole on the side closer to the boiler should be larger. (√) 1. The temperature of the red coke entering the dry quenching furnace is approximately 950 – 1050°C, while the temperature of the circulating gas exiting the dry quenching furnace is 900 – 980°C. (√) 2. When loading red coke in the dry quenching process, maintain the pressure at the loading port between –50 and 0 mmH2O. (√) 3. One of the conditions for stable operation of the furnace when it is shut down is to maintain a stable level of material in the cooling section, which is currently achieved mainly by providing an adequate pre-storage section. (×) 4. The cooling time of red coke in the dry quenching furnace depends solely on the convective heat transfer between the airflow and the coke. (×) 5. Cleaning the newly installed boiler before it starts operating has no impact on future production. (×) 6. The quality of the steam produced by the boiler depends entirely on the quality of the boiler water. (√) 7. The water deoxidation method for the dry quenching coke boiler is atmospheric thermal spray deoxidation. (×) 8. The dust content at the primary dust removal inlet (under standard conditions) is less than 8 g/m3. (√) 9. The chemicals commonly used for dosing in furnaces are N2H4 and Na3PO4. (√) 10. When heating the furnace with gas, the temperature at the upper part of the pre-storage section is used as the main control temperature. (×) 11. In dry quenching of coke, the gas-to-coke ratio should be as high as possible, as this helps to reduce the coke discharge temperature. (×)12. The shorter the dry quenching time of coke in the dry quenching furnace, the better. (√) 13. The automatic alignment device is mainly composed of a hydraulic station and hydraulic cylinders. (×) 14. Before shutting down the boiler for routine maintenance, the inlet temperature of the boiler must be reduced to below 500°C as specified. (×)15. Leakage in the positive-pressure section of dry quenching of coke refers mainly to the leakage between the fan outlet and the inlet of the primary dust removal system. (×) Leaks in the positive-pressure section of the 16 dry quenching system refer mainly to leaks between the fan outlet and the inlet of the primary dust removal system. (√) 17. The upper limit of the liquid level in the drum is located at 150 mm from the center line of the drum. (√) 18. The limitation on the oxygen content in the boiler feedwater is mainly to protect the economizer. (×)19. The lower the steam temperature at the outlet of the waste heat boiler, the better. (√) 20. The better the tightness of the heating device, the greater its production capacity. (√) 1. When loading red coke in the dry quenching process, maintain the pressure at the loading port between –50 and 0 mmH2O. (√) 2. One of the conditions for stable operation of the furnace when it is shut down is to maintain a stable level of material in the cooling section; this is currently achieved primarily by providing an adequate pre-storage section. (×) 3. The quality of the steam generated by the boiler depends entirely on the quality of the boiler water. (√) 4. The water deoxidation method for the dry quenching coke boiler is atmospheric thermal spray deoxidation. (×) 5. The dust content at the primary dust removal inlet (under standard conditions) is less than 8 g/m3. (×) 6. The turnaround time of the coke ovens in the coking plant must not be less than 20 hours. (×) 7. The dry quenching time of coke in the dry quenching furnace shall not exceed 1.5 hours. (×) 8. The cooling time of red coke in the dry quenching furnace depends solely on the convective heat transfer between the airflow and the coke. (×) 9. Before shutting down the boiler for routine maintenance, the inlet temperature of the boiler must be reduced to below 500°C as specified. (×) 10. Leakage in the positive-pressure section of dry quenching mainly refers to the leakage between the fan outlet and the inlet of the primary dust removal system. (×) 11. After the circulating gas automatic analyzer fails, for safety reasons, the amount of air introduced should be reduced. (×)12. When switching pumps, the pump that is currently in operation should be stopped first, before starting the backup pump. (√) 13. The red coke in the pre-storage chamber of the dry quenching furnace does not undergo heat exchange with the circulating gas. (×)14. During air drying, to raise the temperature of the circulating gas, the amount of air introduced should be reduced. (×) 15. When it comes to the opening area of the annular flue, the opening degree of the adjustment hole on the side closer to the boiler should be larger. (√) 16. The temperature of the red coke entering the dry quenching furnace is approximately 950 – 1050°C, while the temperature of the circulating gas exiting the dry quenching furnace is 900 – 980°C. (√) 17. When loading red coke, maintain the pressure at the loading port at –50 to 0 mmH2O. (√) 18. One of the conditions for stable operation is maintaining a stable level of material in the cooling section, which is currently achieved primarily by providing an adequate pre-storage section. (×)19. The cooling time in the dry quenching furnace depends solely on the convective heat transfer between the air flow and the coke. (×) 20. Cleaning the boiler before it starts operation has no impact on future production. II. Fill-in-the-blank questions: 1. Dry quenching of coke originated in (Switzerland). The first company in China to introduce the dry quenching technology was Baosteel. 2. The capacity of the dry quenching unit in the first phase of Benxi Iron and Steel Company’s coking plant is 150 t/h, while the gas production capacity of the boilers is 80 t/h. 3. The primary dust collector uses a gravity sedimentation dust removal device. The secondary dust collector uses a (multi-tube cyclone) type dust removal device. 4. The coke discharge device mainly consists of a flat gate, an (electromagnetic vibrating feeder), a (rotary seal valve), and a coke discharge chute. 5. Dry quenching of coke allows for the recovery of about 83% of the sensible heat contained in the red coke, which is used to generate steam for power generation, **reducing the energy consumption in coke production. 6. An emergency vent device installed at the top of the dust removal system is used to release steam urgently in case of (boiler tube rupture). 7. The loading device is equipped with three operation modes: on-site (manual operation), on-site interlocked operation, and central control PLC interlocked operation. 8. The braking methods for dry quenching coke locomotives include (regenerative braking), disc braking, and air brake. 9. The gas produced after vapor-water separation in the dry quenching boiler is saturated steam. 10. The boiler cleaning methods include (mechanical removal) and (chemical cleaning); dry quenching boilers are generally cleaned using (chemical cleaning). 1. The (flat gate) is fully open under normal operating conditions; it is closed during annual maintenance or (chute cleaning) to stop the flow of (coke). 2. The coking drum mainly consists of the drum body, as well as the swinging (bottom gate) and (lifting rod). 3. The primary dust collector uses a gravity sedimentation dust removal device. The secondary dust collector uses a (multi-tube cyclone) type dust removal device. 4. The coke discharge device mainly consists of a flat gate, an electromagnetic vibrating feeder, a rotary seal valve, and a coke discharge chute. 5. The three pneumatic valves of the dry quenching furnace are: (pre-storage chamber pressure regulation), (air introduction), and (pre-storage chamber return). 6. The (emergency vent device) installed at the top for dust removal is used to urgently release steam in the event of a (boiler tube rupture). 7. The loading device is equipped with three operation modes: on-site (manual operation), on-site interlocked operation, and (central control PLC interlocked operation). 8. The set pressure of the safety valve for drum control is (5.05) Pa, and its operating set pressure is (5.15) Pa. 9. The gas generated after steam and water separation in a dry quenching boiler is (saturated steam). 10. Sampler testing of four types of samples: boiler feed water, furnace water, saturated steam, and superheated steam. 1. Water deoxidization is achieved through (physical deoxidization) and (chemical deoxidization); (Na3PO4) is added for adjustment in order to prevent scaling in the boiler. 2. Dry quenching of coke originated in (Switzerland). The first company in China to introduce the dry quenching technology was Baosteel. 3. The coking drum mainly consists of the drum body, as well as the swinging (bottom gate) and (lifting rod). 4. The dry quenching system mainly consists of: (circulating gas system), (steam and water system), (coke cooling system), and (dust removal system). 5. The pre-storage section of the dry quenching system is equipped with two types of level sensors: (gamma rays) and (capacitance). 6. The coke discharge device mainly consists of a flat gate, an electromagnetic vibrating feeder, a rotary seal valve, and a coke discharge chute. 7. The designed gas-to-coke ratio for the dry quenching process in Phase 1 of Benxi Iron and Steel Company’s coking plant is approximately (1280) m3/t of coke, with a coke discharge temperature of less than 200°C. 8. The dry quenching of coke is divided from top to bottom into three sections: (pre-storage section), (chute area), and (cooling section). 9. Dry quenching of coke allows for the recovery of about 83% of the sensible heat contained in the red coke, which is used to generate steam for power production, **reducing the energy consumption in coke production**. III. Multiple-choice questions:
1. Which of the following is not a safety accessory for a boiler’s drum? C
A. Safety valve
B. Pressure gauge
C. Flow meter

2. During the process of increasing or decreasing pressure in a dry quenching boiler, the temperature difference between the upper and lower walls of the boiler drum should not exceed (B)
A. 40°C
B. 50°C
C. 60°C

3. The location where boiler tubes suffer the most corrosion is (C)
A. Evaporator
B. Superheater
C. Economizer

4. The main purpose of warm air drying is (A)
A. To remove moisture from the refractory material
B. To heat the refractory material
C. To reduce the temperature difference between the refractory material and the red coke inside the dry quenching furnace

5. The normal water temperature after deoxygenation using an oxygen remover is (C)
A. 100°C
B. 110°C
C. 104°C

6. The pH level of boiler feedwater should be controlled at (A)
A. 8.5–9.2
B. >7
C. 8–9.5

7. In dry quenching processes, (C) is used as a carrier.
A. Air
B. CO2
C. N2

8. A dry quenching boiler is equipped with (B) level gauges. A、2 B、3 C、4 The content of component (C) that must be controlled in the circulating gas. A. CO2 H2 O2 B. CO2 H2 CO C. CO H2 O2. It is most reasonable to place the neutral zone for the gas pressure in the dry quenching process at (C). A、1DC B、Cooling section C、Storage section. 11. The instrument used to measure the concentration of CO in the circulating gas is (B). A、Thermiconductometer B、Infrared analyzer C、Magnetic oxygen analyzer. 12. The steam temperature at the inlet of the secondary superheater is controlled at (A). A、Above the saturation temperature B、Below the saturation temperature C、Equal to the saturation temperature. 13. From the perspective of the composition of the coke, dry quenching results in an increase in the coke dust ratio (A). A、Increase B、Remain unchanged C、Decrease. 14. The rated pressure and temperature of the boiler are (C). A、4.0 MPa, 430°C B、4.3 MPa, 460°C C、4.3 MPa, 480°C. 15. When the dry quenching system is operating properly, (A). A. The elevator is equipped with automatic control. B. The elevator is equipped with central manual control. C. The elevator is equipped with local control. 16 When the dust removal fan stops operating and the backup system is not activated, (C) measures must be taken for dry quenching of coke. A. Coke can be loaded and discharged. B. Stop loading and discharging coke. C. Coke cannot be loaded but can be discharged. 17. The instrument used to measure the CO concentration in the circulating gas is (B). A. Heat conduction meter. B. Infrared analyzer. C. Magnetic oxygen analyzer. 18. The steam temperature at the inlet of the secondary superheater is controlled at (A). A. Above the saturation temperature. B. Below the saturation temperature. C. Equal to the saturation temperature. 19. From the perspective of the composition of fully coked carbon, dry quenching results in a change in the metallization rate of (C). A. An increase. B. No change. C. A decrease. 20. The rated pressure and temperature of the boiler are (C). A. 4.0 MPa, 430°C. B. 4.3 MPa, 460°C. C. 4.3 MPa, 480°C. 1. Compared to coke produced by wet quenching, coke produced by dry quenching has the following characteristic (A). A. Uniform particle size; B. Reduced strength; C. Increased cracks. 2. The inner layer is N3, the middle layer is A1, and the outer layer consists of ceramic fiber mineral wool filler along with casting material – this is the masonry structure of a dry quenching furnace (A). A. Pre-storage section cone part B. Cooling section C. Chute area 3. The rated pressure and temperature of the boiler are (C). A. 4.0 MPa 430°C B. 4.3 MPa 460°C C. 4.3 MPa 480°C 4. The feedwater temperature of the boiler is (C) °C. A、920 B、130 C、104 3、The rated pressure and temperature of the boiler are (C). A. 4.0 MPa at 430℃ B. 4.3 MPa at 460℃ C. 4.3 MPa at 480℃ 4. The calorific value of coke oven gas is generally (B). A、4000 — 5000 B、3600 — 4400 C、17000—17600 5、Among the following refractory materials, the one with better mechanical strength and wear resistance is (A). A. Silica brick B. Cylinder brick C. High-alumina brick 6. The constant-pressure heating of a boiler takes place in (C). A. Water wall B. Economizer C. Evaporator 7. The secondary superheater uses (B) as its heating method. A. Downstream B. Upstream C. Mixed flow 8. The steam temperature at the inlet of the secondary superheater is controlled at (A). A. Greater than saturation temperature B. Less than saturation temperature C. Equal to saturation temperature 9. The instrument used to measure the concentration of CO in circulating gas is (B). A. Heat conduction meter B. Infrared analyzer C. Magnetooxidation analyzer 10. The pH of boiler feedwater should be controlled at (A). A、8.5 — 9.2 B、＞7 C、8 — 9.5 11、Dry quenching of coke uses (C) as a carrier. A. Air B. CO2 C. N2 12. The area where boiler tubes suffer the most corrosion is (C). A. Evaporator B. Superheater C. Economizer 13. A dry quenching coke boiler has (B) safety valves. A、2 B、3 C、4 14. It is most reasonable to locate the pressure neutral zone in the dry quenching of coke cycle at (C). A、1DC B、Cooling section C、Storage section 15、When the inlet temperature of the waste heat boiler is high, (A) should be used. A. Introduce N2 B. Introduce air C. Increase the amount of coke discharged 16. When the inlet temperature of the waste heat boiler is high, (A) should be used. A. Introduce N2 B. Introduce air C. Increase the amount of coke discharged 17. Boiler corrosion is mainly of type (C) corrosion. A. Dew point B. Scaling C. Oxygen 18. The normal value for the vibration of the circulation fan bearings is (B) A. 40μm B. 32μm C. 42μm 19. The low-pressure alarm value for the compressed air used in instruments is (A) A. 4kgf/cm2 B. 6 kgf/cm2 C. 8 kgf/cm2 20. The pH level of boiler feedwater should be controlled at (A) A. 8.5–9.2 B. >7 C. 8–9.5 1. Compared to coke produced by wet quenching, coke produced by dry quenching has the following characteristic (A). A. Uniform particle size B. Reduced strength C. Increased cracks 2. The material of the split-bottom gate in the coking tank is (B). A、HT250 B、0Cr19Ni10NbN C、KMTBCr26 3、One of the maintenance methods used when a boiler is not in use for an extended period of time is to fill it with ( A ). A. Demineralized water B. Hard water C. Natural water 4. What is located between the primary superheater and the secondary superheater in a boiler? (C) A. **Pressure reduction device B.** Temperature and pressure reduction device C. **Temperature reduction device 5. To ensure the tightness of rotary seal valves, (A) is used. A. Fill with N2 B. Fill with compressed air C. Fill with air 6. The three-element control for the drum water level is achieved by adjusting the feedwater flow rate, the drum water level, and (B). A. Main steam pressure B. Main steam flow C. Main steam temperature 7. Coke with a particle size greater than (A) is called metallurgical coke, which can be used in blast furnaces for smelting. A、25 mm B、40 mm C、60 mm 8、The normal liquid level of the drum is at (A) below the drum’s centerline. A、100mm B、150mm C、250mm 9、The basis for determining the boiler’s exhaust flow rate (B) depends on the test results. A. Feed water B. Boiler water C. Deionized water. 10. A masonry structure with BM on the inner layer, N3 in the middle layer, and A1 on the outer layer belongs to (C). A. Pre-storage section B. Lower pre-storage chamber section C. Cooling section. 11. It is most reasonable to locate the pressure neutral zone of the dry quenching cycle gas in (C). A、1DC B、Cooling section C、Storage section 12、When the dust removal fan stops operating and the backup system is not in use, what measure must be taken for dry quenching of coke at this time? (C) A. Coke can be loaded and discharged. B. Stop loading and discharging coke. C. Coke cannot be loaded but can be discharged. 13. The instrument used to measure the CO concentration in the circulating gas is (B). A. Thermocouple thermometer B. Infrared analyzer C. Magnetooxidation analyzer 14. The area where boiler tubes suffer the most corrosion is (C). A. Evaporator B. Superheater C. Economizer 15. The constant-pressure heating of a boiler takes place in (C). A. Water wall B. Economizer C. Evaporator. 16 When the dust removal fan stops operating and the backup system is not in use, (C) measures need to be taken for dry quenching of coke. A. Coke can be loaded and discharged. B. Stop loading and discharging coke. C. Coke cannot be loaded but can be discharged. 17. The instrument used to measure the CO concentration in the circulating gas is (B). A. Heat conduction meter. B. Infrared analyzer. C. Magnetic oxygen analyzer. 18. The steam temperature at the inlet of the secondary superheater is controlled at (A). A. Above the saturation temperature. B. Below the saturation temperature. C. Equal to the saturation temperature. 19. From the perspective of the composition of fully coked material, dry quenching results in a change in the metallization rate of (C). A. An increase. B. No change. C. A decrease. 20. The rated pressure and temperature of the boiler are (C). A. 4.0 MPa, 430°C. B. 4.3 MPa, 460°C. C. 4.3 MPa, 480°C. IV. Short-answer questions 1. What is foaming? Answer: It refers to the phenomenon where, as steam and water rise on the evaporation surface of a boiler, a large number of bubbles are generated, resulting in a mixture of steam and water. 2. What is dew point? Answer: The temperature at which certain gases in flue gas begin to liquefy. 3. What are the purposes and functions of operating a boiler cleaning process? Answer: Through cleaning, deposits such as scale, salt deposits, and metal corrosion products that form during boiler operation are removed. Keep the inner surface of the heating surfaces clean to improve thermal efficiency and prevent accidents caused by scaling or other issues on those surfaces. 4. What is saturated steam? Answer: Steam generated when water is heated to its saturation temperature. 1. What are the disadvantages of dry quenching of coke? Answer: (1) High investment and complex technology. ⑵ Coke has low moisture content, resulting in high dust removal costs. ⑶ There are many operating devices, resulting in high electricity consumption. ⑷ The coke has burn damage. ⑸ The dust ratio increases, while the metallurgical coke ratio decreases. 2. What is dew point? Answer: The temperature at which certain gases in flue gas begin to liquefy. 3. What is latent heat of vaporization? Answer: The heat required for a unit weight of liquid to turn into dry saturated vapor at the boiling temperature. 4. If the pressure after the low-pressure steam pressure regulator is to be increased, what adjustments should be made to the regulator body? Answer: Loosen the fixing nut of the valve body adjustment bolt, turn the adjustment bolt clockwise until the desired pressure is reached, then lock the nut. 1. Briefly describe the purpose and functions of cleaning operating boilers. Answer: Through cleaning, deposits such as scale, salt deposits, and metal corrosion products that form during boiler operation are removed. Keep the inner surface of the heating surfaces clean to improve thermal efficiency and prevent accidents caused by scaling or other issues on those surfaces. 2. What is the basic principle of dry quenching technology? Answer: Dry quenching of coke involves using inert gases (mainly nitrogen) to extinguish the red coke produced in coke ovens within a dry quenching furnace. After absorbing heat, these inert gases enter a boiler where they exchange heat with deionized water to generate medium-pressure steam. The inert gases are recycled through circulation fans, and the coke that has been dried quenched is transported to subsequent processing stages via a coke discharge system. The steam produced is used for power generation or heating. 3. What are the main equipment for dry quenching of coke? Answer: The main equipment for dry quenching of coke includes motor cars, coke tank cars (including the coke tanks and transport vehicles), automatic alignment devices, elevators, circulation fans, loading devices, dry quenching furnaces, gas supply systems, coke discharge systems, dry quenching boilers, as well as primary and secondary dust collectors. 4. Why must the pressure in the pre-chamber be controlled at zero? Answer: (1) To prevent gases from escaping inside the furnace or excessive amounts of external air from entering during coke loading ； ⑵ Maintain stability in circulatory system pressure ； ⑶ Prevent air from entering and causing coke burnout. V. Essay Questions 1. Briefly describe the phenomenon of coke floating at the inclined chute entrance of a dry quenching furnace 1 The pressure of the circulating gas at the boiler inlet is lower than the normal operating pressure. When the speed of the 2-cycle fan remains unchanged, the decrease in the volume of circulating air is significant. With 3 rows of coke discharge, the boiler inlet temperature rises significantly. The ash discharge valve with a water-cooled sleeve arrangement at the lower part of 41DC is blocked by coke lumps, preventing normal ash discharge. 5 The pressure in the pre-storage section of the dry quenching process increases, and the pressure control valve in this section is unable to regulate it effectively. 2. Briefly describe the process flow of the dry quenching gas cycle? Answer: 1. The power is generated by the circulating fan; it flows through the feedwater preheater to the dry quenching furnace, enters the primary dust collector via the circulating air duct, the gas exiting the primary dust collector goes into the boiler, and finally returns to the circulating fan after passing through the secondary dust collector. 2 Due to resistance, the entire process of the circulating gas involves a decrease in pressure followed by an increase. 1. What are the regular blowdown operations for boilers and the precautions to take? Answer: ① First, open the secondary regular blowdown valve slowly, then open the primary regular blowdown valve quickly. ② When shutting down, first close the regular blowdown valve quickly, then close the regular blowdown valve No. 2 slowly.③ Each regular blowdown should not last more than 30 seconds; it is normal to perform this operation once per shift. ④ Drainage cannot be carried out simultaneously on the same header. 2. Why is it necessary to maintain the integrity of the CDQ circulating gas system? Answer: (1) Reduce coke burn loss ； ⑵ Preventing flammable gas explosions and backfires ； ⑶ Prevent gas leakage at the positive pressure area to avoid human poisoning ； ⑷ Prevent fires caused by the leakage of high-concentration flammable gases ； ⑸ Maintain stable reservoir pressure ； ⑹ It prevents combustion of the coke at the bottom of the dry quenching furnace in the event of a prolonged failure of the fan (an excessively long downtime). 1. Why must the temperature be reduced to 600°C before shutting down the furnace for routine maintenance? Answer: When the CDQ unit stops operating, a large amount of heat remains stored inside components such as the dust collector and the boiler walls. This heat continues to be transferred to the tubes in the boiler’s heating surfaces. When the temperature at T6 becomes too high, the heat storage effect can lead to overheating and damage of these tubes. The maximum temperature that the superheater in a CDQ boiler can withstand is around 600°C; therefore, to ensure the safety of the boiler, the temperature at T6 is reduced to 600°C during regular maintenance. 2. Briefly describe the phenomenon of coke floating at the inclined chute entrance of the dry quenching furnace. Answer: (1) The pressure of the circulating gas at the boiler inlet is lower than the normal operating pressure. (2) The decrease in the volume of circulating air is significant when the speed of the circulation fan remains unchanged. (3) Coke discharge temperature; the boiler inlet temperature rises significantly. (4) The ash discharge valve of the water-cooled sleeve type at the lower part of 1DC is blocked by coke lumps, preventing normal ash discharge. (5) The pressure in the dry quenching coke pre-storage section rises, and the pressure control valve in this section cannot regulate it effectively.

We conduct training tests for new employees every month, and we refer to our colleagues’ study materials – thank you

Thank you so much! They are all necessary materials. . I can only give 2 points at a time, so I gave you 2 points for each one. :victory: Thank you! ! !

Boiler Knowledge Review Materials I. Term Explanations: 1. Pressure: refers to the force acting vertically on a unit area. 2. Gauge pressure: refers to the pressure difference with the ambient atmospheric pressure as the reference pressure. 3. Absolute pressure: refers to the pressure with respect to a reference pressure of the component. 4. Vacuum gauge: It refers to a pressure gauge used to measure negative pressure. 5. Evaporation rate: The amount of steam generated per hour by the boiler per square meter of area. 6. Evaporation rate: The amount of steam generated by the boiler per hour, measured in tons per hour. 7. Convection: refers to the process of heat transfer through the flow of gases and liquids. 8. Vaporization: refers to the phenomenon in which a substance changes from a liquid state to a gas state. 9. Steam space: refers to the space occupied by steam at the upper part of the boiler’s drum. 10. Temperature: A physical quantity that indicates the degree of hotness or coldness of a reference material. 11. Maximum continuous evaporation rate: It is the maximum evaporation rate that a steam boiler can achieve when operating continuously for an extended period under rated steam parameters, rated feedwater temperature, and with the designed fuel. 12. Water circulation circuit: In natural circulation and forced circulation boilers, it is a closed evaporation system composed of downcomers, upcomers, the boiler drum, and the header (or lower boiler drum). 13. Saturation temperature of water: When water is heated at a certain pressure, its temperature rises to a certain point at which it begins to vaporize. During this vaporization process, the temperature remains constant until all the water has vaporized; this temperature is known as the saturation temperature of water. 14. Stalled water circulation: In pipes with weak heating, when the effective head is too low to overcome the resistance in the downcomer, the flow velocity of the working fluid in the upcomers on the evaporation surface becomes extremely low, resulting in a stagnation of the amount of water circulating into the upcomers at certain points. 15. Steam-water stratification: The phenomenon in which a steam-water mixture flows through a horizontal or slightly inclined pipe, and at low flow rates, water stays in the lower part while steam is in the upper part, resulting in stratified flow. 16. Backflow in the water cycle: In tubes that are less heated, the effective head cannot overcome the resistance in the downward-flowing tubes; as a result, the tubes through which the fluid originally flowed upward become tubes through which the fluid flows downward, a phenomenon known as backflow. 17. Membrane-type water wall: The water wall tubes are connected using flat steel strips, or fins are used on the tubes to connect them together, thereby forming a unified water wall structure. 18. Secondary scale: There are two types of water sludge; one type does not stick easily to the heating surfaces, while the other type sticks easily to them. The sticky slag, after being baked on the heated surface, turns into scale, known as secondary scale. 19. Dry maintenance: After the boiler is taken out of service, the water inside it is drained to remove scale and sediment, and the heating surfaces are dried. Then, desiccants are placed in the boiler drum and header, and the access openings are sealed to isolate them from the atmosphere. 20. Saturated water: Water that has reached its saturation temperature but has not vaporized is called saturated water. 21. Saturated steam: Steam produced by the vaporization of water at its saturation temperature is saturated steam. 22. Opening height: The actual lift of the safety valve disc from its closed position. When calibrating a safety valve, the required opening height refers to the opening height under discharge pressure conditions. 23. Unit plant: One boiler is paired with one steam turbine, forming an independent thermal system; the main steam pipeline and main feedwater pipeline are separate from those of other units. 24. Fixed carbon: The solid substance composed of carbon and ash that remains after the volatiles in a fuel have been separated and burned; the carbon in this substance is referred to as fixed carbon. 25. Lower calorific value: Volatiles in the fuel burn and form water vapor, and the moisture present in the fuel also turns into vapor. The lower heating value is the fuel heating value minus the latent heat of water vapor. 26. Air leakage coefficient: The difference in the excess air coefficient of the flue gas at the inlet of the flue gas passage, or the ratio of the difference in the air volume at the inlet of the air passage to the theoretical air volume. 27. Wind pressure test: A pressure test using air on the furnace chamber or flue at specified pressures and for a defined duration, to verify its airtightness. II. Fill in the blanks: 1. The water level gauge should be installed in a place that is convenient for (observation). 2. Glass tube level gauges also come equipped with protective devices such as (protective covers, quick-close valves, and automatic locking mechanisms). 3. A centrifugal water pump is composed of a pump casing, bearing housing, impeller, packing, and packing gland. 4. Boiler water treatment methods can be divided into two main categories: in-furnace chemical water treatment and off-furnace chemical water treatment. 5. At one atmosphere of pressure, water’s temperature rises as it is heated and absorbs heat; when the water is heated to 100 degrees, it boils. 6. The boiler feedwater system shall ensure a reliable water supply. 7. During boiler operation, it is necessary to maintain stable air pressure, which must not exceed the allowable pressure. 8. Heat transfer in a boiler occurs through three mechanisms: radiation, convection, and conduction. 9. In industrial boilers, the heat-exchanging surfaces where convective heat transfer plays a major role include convective tube banks, superheaters, economizers, and flue tubes. 10. The erosion of convective heating surfaces by flue gas occurs in two ways: longitudinal erosion and lateral erosion, among which lateral erosion results in better heat transfer performance. 11. The spring-type safety valve adjusts its opening pressure by rotating the adjustment nut to compress or relax the spring. 12. The methods for deoxidizing boiler feed water include chemical deoxidation, vacuum deoxidation, stripping deoxidation, and thermal deoxidation. 13. Common faults in the water circulation include stagnation, backflow, and vapor-water stratification. 14. Based on their physical state, fuels can be divided into three categories: solid fuels, liquid fuels, and gaseous fuels. 15. The components of the smoke generated during coal combustion are carbon dioxide, carbon monoxide, and sulfur dioxide. 16. Coal is classified into four types—anthracite, bituminous coal, lignite, and peat—based on its age of formation and degree of carbonization. 17. The arrangement types of forced-circulation hot water boilers are divided into co-current, counter-current, and mixed types according to the flow direction of flue gas and the flow direction of water in the boiler; co-current or mixed types are commonly used. 18. In boilers whose water level is monitored by remote water level gauges, at least two reliable remote water level gauges shall be installed in the control room; each such gauge shall have clear markings at the highest and lowest safe water level marks specified in the operating procedures. 19. After the safety valve passes the calibration, a label should be attached to the seal; the label must indicate the name of the calibration facility, the calibration number, the registration number of the equipment in question, the set pressure, and the date of the next calibration. 20. The calibration of safety valves on operating boilers and pressure vessels can be carried out either on the equipment itself or by removing them from the equipment for calibration. 21. Before testing a safety valve, it should be disassembled for inspection; thereafter, its set pressure and sealing test pressure should be checked. Safety valves that pass these tests must be sealed with lead and labeled. 22. The total discharge capacity of the safety valves on steam boilers must be greater than the boiler’s maximum continuous evaporation rate; moreover, when all safety valves on the drum and superheater are opened, the steam pressure inside the drum shall not exceed 1.1 times the design pressure. 23. After the safety valve of a steam boiler is calibrated, the test results such as its opening pressure, setting pressure, and returning pressure should be recorded in the boiler’s technical documentation. 24. To ensure the safe operation of boilers and pressure vessels and to protect people’s lives and **property, the State Council has issued the Interim Regulations on the Safety Supervision of Boilers and Pressure Vessels. 25. The Interim Regulations on the Safety Supervision of Boilers and Pressure Vessels stipulate that plans for major repairs and modifications to the pressure-bearing components of boilers and pressure vessels must be submitted to the local authority responsible for the safety supervision of boilers and pressure vessels for review and approval. 26. After the safety valve has passed the calibration, the calibration agency shall issue a report, and it shall be reviewed and signed in accordance with the provisions of the agency’s quality assurance system and management procedures. The calibrator shall evaluate the report and inspect the safety valve in line with the requirements of relevant regulations and standards. 27. When the inner diameter control method is used for boiler tube expansion, the expansion rate should generally be within the range of 1%-2%. 28. Steam pressure gauges should be calibrated at least once a year, and they must be sealed after calibration. 29. The steam boiler feed water stop valve shall be installed between the boiler drum and the water check valve, and connected directly to the feed water return valve. 30. Steam boilers with a rated evaporation capacity of more than 4 tons per hour shall be equipped with automatic water supply regulators, and manual water supply devices shall be installed at a location easily accessible to the boiler operator. 31. During the water pressure test of a steam boiler, the water pressure should be increased or decreased gradually. When the pressure reaches the operating pressure, the increase in pressure should be paused temporarily to check for any leaks or abnormalities, before continuing to raise the pressure to the test level. 32. The \"Regulations on Safety Technical Inspection of Hot Water Boilers\" apply to fixed hot water boilers that use water as the medium and meet the following conditions simultaneously: 1. The rated power is greater than or equal to 0.1 WM. 2. The rated outlet water pressure is greater than or equal to 0.1 Mp. 33. The accuracy of the pressure gauge used in hot water boilers is not lower than grade 2.5. 34. Install a bypass pipe with a check valve between the pipelines before and after the circulation pump in forced-circulation hot water boilers to prevent water hammer when the pump stops suddenly. 35. During the boiler water pressure test, the pressure retention time at the test pressure for the following types of boilers is: 5 minutes for welded boilers, 20 minutes for riveted boilers, and 30 minutes for cast iron boilers. 36. For major repairs to the pressure-bearing components of a boiler, drawings and construction technical plans must be available. 37. The furnace structure of the boiler should have sufficient pressure resistance and reliable explosion-proof measures, as well as good sealing properties. 38. The “Regulations on Safety Technical Inspection of Steam Boilers” stipulate that the safety technical management related to the use of power generation boilers in electrical systems, as well as the requirements for boiler operators, shall be carried out in accordance with the “Regulations on Inspection of Industrial Boilers in the Electric Power Industry” and relevant provisions. The management of safety technical regulations for the boilers used in self-provided power plants is carried out in accordance with the regulations set by the power sector. 39. The “Regulations on Safety Technical Inspection of Steam Boilers” stipulate that the load-bearing structure of a boiler must possess sufficient strength, stiffness, stability, and corrosion resistance when subjected to design loads. 40. The ‘Regulations on Safety Technical Inspection of Steam Boilers’ stipulate that for boilers equipped with split-type cast-iron economizers, in order to prevent the economizer from being damaged, bypass flues or other effective measures should be employed, and a bypass water circuit should also be installed. 41. The discharge capacity of the safety valves at the superheater and reheat gas outlets shall ensure sufficient cooling of the superheater and reheat gas when the safety valves operate. 42. Boilers with a rated steam pressure of 450 degrees Celsius or higher shall be equipped with steam temperature recording instruments, as well as alarms for high and low temperatures. 43. The ‘Inspection Regulations for Industrial Boilers in the Power Industry’ apply to boilers with superheated steam pressure of 3.82 MPa or higher. Fixed steam boilers for generating power by burning fuel. Power generation boilers with superheated steam pressure below 3.82 MPa may refer to this for implementation. 44. Wet steam is composed of saturated liquid and dry saturated vapor. 45. The main purpose of the reheat cycle is to increase the dryness at the turbine exit. 46. At one atmosphere of pressure, the saturation temperature of water is 100°C. 47. The pressure under standard conditions is P = 101.25 KPa, T = 273.15 K, and V = 0.0224 cubic meters. 48. Thermal conductivity is a parameter that indicates the efficiency with which a material conducts heat, and its unit is W/M*K. 49. Metal materials have the highest thermal conductivity, liquids have an intermediate value, while gases have the lowest. 50. Forces acting on a liquid are generally divided into two main categories: body forces and surface forces. Fluid particles are uniformly subjected to a force proportional to their mass, and this force is known as a mass force. A force acting on the surface of the fluid under study and proportional to the surface area of the fluid is called a surface force. 51. The surface force per unit area is called stress, which is often divided into tangential stress and normal stress. In a stationary fluid, there is no tangential stress; only normal stress exists. 52. Fluids with a high volumetric elastic modulus have low compressibility, while fluids with a low volumetric elastic modulus have high compressibility. 53. The magnitude of internal friction in a fluid is proportional to the velocity gradient of the fluid and the size of the contact area, and it is also related to the properties of the fluid, namely its viscosity. 54. As the temperature rises, the viscosity of liquids decreases, while the viscosity of gases increases. 56. A boiler is a device that uses the thermal energy released by the combustion of fuel or other heat sources to heat water or other fluids to certain specified parameters. 57. The rear heating surfaces of the boiler are the gas economizer and air preheater. 58. Coal-fired boilers can be classified into two types based on the ash discharge method: solid ash discharge and liquid ash discharge. 59. The main components of fuel are: carbon, hydrogen, oxygen, nitrogen, sulfur, ash, and moisture. 60. A gap should be left at the junction of the chimney and the roof of a small boiler, and cables should be installed on tall chimneys. To prevent the chimney from being blown away by the wind. 61. By fuel is meant the chemical reaction process in which the combustible substances within the fuel react with oxidizers ； During the reaction, intense heat is released, raising the temperature of the combustion products. 62. The main factors affecting the heat loss of a boiler are its external surface area, surface temperature, furnace wall structure, and the temperature of the surrounding environment. 63. The safety valve is a major safety accessory of a boiler. When the pressure inside the boiler rises above the allowable level and the strength of the boiler’s pressure-bearing components is no longer sufficient, the boiler is at risk of exploding. 64. Currently, the common types of safety valves used in industrial boilers are lever-type and spring-type; in the past, weight-type and combined-type valves were also used. 65. The water level gauge is used to indicate the water level inside the boiler, serving to monitor the dynamics of the water level there in order to keep it within normal limits. 66. Gate valves should be used for the inlet pipes of centrifugal pumps in the boiler room, while globe valves can be used for the outlet pipes. 67. A check valve, often referred to as a foot valve, should be installed at the lower end of the suction pipe of the boiler water pump. 68. Water hardness is classified into calcium hardness and magnesium hardness based on the substances that cause it. 69. The water that can be supplied to boilers includes natural water and treated water. 70. There are six methods for dealkalizing boiler feed water: acid addition, lime treatment, hydrogen ion exchange, ammonium-sodium ion exchange, chloride-sodium ion exchange, and salt treatment. 71. The hazards of poor water quality to boilers include scaling, corrosion, and foaming. 72. The causes of boiler explosions include overpressure, overheating, corrosion, cracking, deficiencies in design and manufacturing, and water hammer.