Question banks on hydrocracking and hydrorefining

This year, Sinopec and CNPC are holding competitions for hydrocracking technologies; I hope everyone will engage in more exchanges.

1. Hydrocracking question bank, Hydrorefining question bank: http://bbs.hcbbs.com/viewthread.php?tid=122263 Hydrorefining question bank: http://bbs.hcbbs.com/viewthread.php?tid=146554 2. Hydrocracking question bank, Questions related to accident handling in hydrocracking: http://bbs.hcbbs.com/viewthread.php?tid=112296 Does anyone among the forum members have question banks for hydrocracking skill competitions?: http://bbs.hcbbs.com/viewthread.php?tid=289256&page=1#pid1402712 Hydrocracking exam questions: http://bbs.hcbbs.com/viewthread.php?tid=386171 A set of hydrocracking exam questions has been uploaded: http://bbs.hcbbs.com/viewthread.php?tid=290208 Questions related to hydrocracking positions: http://bbs.hcbbs.com/viewthread.php?tid=190575 Exam questions for hydrocracking unit operators and technicians: http://bbs.hcbbs.com/viewthread.php?tid=147194 Hydrocracking question bank: http://bbs.hcbbs.com/viewthread.php?tid=39817 Collection of training questions on operating procedures for refining units – Hydrocracking units: http://bbs.hcbbs.com/viewthread.php?tid=11739

Training question bank for diesel hydrorefining operators: Question 1: How to adjust fluctuations in the distillation overhead temperature? I. Operation steps: 1. Enable the cascade control valve for tower top temperature and reflux rate ； 2. Stable return flow rate ； 3. Strengthen the water cutting operation in the return tank ； 4. Stable feed temperature ； 5. Stabilize the outlet temperature of the heating furnace ； 6. Adjust the appropriate bottom circulation rate ； 7. Understand the reasons for changes in feed composition, and make adjustments based on the key operating principles ； 8. Pressure at the top of the stabilizer tower ； 9. If the instrument malfunctions, contact an instrument technician for repair. II. Requirements: 1. The top of the tower temperature should be adjusted and controlled based on the dry point of the gasoline product at the tower top; if the dry point is high, the top of the tower temperature must be reduced ； 2. The top temperature of the tower is controlled by the reflux rate; the normal temperature is 169℃ ； 3. The dry point of gasoline is also related to the top pressure of the tower; this pressure is generally kept at around 0.35 Mpa. Question 2: How to control the oxygen content in flue gas? I. Operating steps: 1. For natural draft furnaces, the greater the opening of the air dampers and flue dampers, the higher the oxygen content; otherwise, it is lower ； 2. When the wind is strong, it is necessary to appropriately reduce the opening of the flue dampers and air valves ； 3. During rainy weather when the air pressure is low, the flue dampers should be opened appropriately ； 3. For forced-air furnaces, the higher the opening degree of the butterfly valve at the fan inlet and the butterfly valve at the outlet, the higher the oxygen content; otherwise, it is lower. II. Requirements: 1. Different heating furnaces should be treated separately; a one-size-fits-all approach is not applicable ； 2. Changes in weather conditions have a significant impact on the oxygen content in flue gas, and this should be taken into account. Question 3: What is the method to address the high dry point of the distillation overhead gasoline? I. Operating steps: 1. Reduce the temperature at the top of the tower ； 2. Reduce the bottom temperature of the tower ； 3. Reduce the feed temperature ； 4. Strengthen concurrent dehydrating effect ； 5. Increase the operating pressure of the tower ； 6. Appropriately increase the return flow rate. II. Requirements: 1. To maintain product quality and increase the operating pressure of the tower, it is necessary to raise the temperature accordingly ； 2. One should start with the main contradiction of the problem ； 3. It should be adjusted slowly. Question 4: What are the steps for a normal shutdown? I. Operating steps: 1. Cool down and turn off the engine ； 2. Steam purging of the furnace chamber ； 3. Use large vents to allow natural cooling; if necessary, open the flue dampers to accelerate cooling. 4. Close the main gas valve, vent any remaining pressure through a flare, and finally clean everything with steam. II. Requirements: 1. When cooling down, the burner can be gradually reduced until it is completely turned off ； 2. The cooling process should be carried out at a speed that meets the process requirements ； 3. The smoke induction machine stops operating after all the burners have gone out. Question 5: How is scanning carried out? I. Operation steps: 1. First, sweep the heavy oil pipeline, then the light oil pipeline ； 2. The heat exchanger should first be purged through the main line, and then through the secondary line ； 3. First, cut off the cooling water supply, drain all the remaining water by releasing it from behind the inlet valve, and then use steam to clean the lines ； 4. The control valve should first be flushed through the bypass line, and then through the main line of the control valve ； 5. The tee merging valve should be moved back and forth during cleaning ； 6. The gasoline and condensed oil systems should first be flushed with water to remove all the oil, and then purged with steam. II. Requirements: 1. The pressure-holding scanning method must be used for scanning ； 2. When draining oil into the oily wastewater system, it must be rinsed with hot water ； 3. Line scanning should be carried out in accordance with the procedures and regulations ； 4. When supplying steam, all condensate water must be removed from it; it is not allowed to feed steam containing water into the hot oil pipelines ； 5. Before performing line cleaning, the inlet and outlet valves of the shell side or tube side of the heat exchanger that are not to be cleaned should be kept at a certain opening degree to avoid pressure buildup ； 6. For the cooler, stop the water supply, close the inlet and outlet valves, and open the vent ； 7. Ensure that all oil in the container has been drained before performing line cleaning, and the bottom drain valve should be opened ； 8. When cleaning the inside of the centrifugal pump, the cooling water for the pump must be turned on; after cleaning is complete, open the plug on the pump to drain the condensate, and then turn off the cooling water ； 9. At the end of the line cleaning process, the relevant connection valves should be closed first, followed by shutting off the steam supply, to strictly prevent cross-contamination. Question 6: How is the load of the heating furnace adjusted? I. Operation steps: 1. For reducing the furnace’s output, the burners should be turned down gradually; when they reach the minimum setting, any extra burners should be shut off. At the same time, the air vents and smoke deflectors need to be adjusted accordingly ； 2. For increasing the furnace’s capacity, gradually increase the power of the burners or add more burners, while adjusting the air valves and smoke dampers accordingly ； II. Requirements: 1. Different approaches should be adopted depending on the changes in the furnace load ； 2. While ensuring a stable outlet temperature of the furnace, the load at the four corners of the furnace chamber should vary in accordance with the overall load; sudden changes are strictly prohibited ； Question 7: How to prevent backfire in a heating furnace? I. Steps: 1. Strengthen oil removal from the gas tank ； 2. Determine the correct position of the smoke baffle, and be careful not to close it too tightly when adjusting it ； 3. Do not operate under overload conditions to ensure that a negative pressure is maintained inside the furnace at all times ； 4. Strengthen equipment management, including gas valves, flashback arrestors, etc ； 5. Before ignition, it is necessary to check carefully and make the necessary preparations. II. Requirements: 1. The gas valve should be opened slowly before ignition ； 2. Before ignition, the furnace must be purged with steam for 10–15 minutes, until steam is visible at the chimney ； 3. If ignition fails, be sure to purge the furnace with steam before attempting to ignite it again. Question 8: How to light a heating furnace? I. Steps: 1. Preparation work ； 2. Maintain the pressure in the gas pressure tank at around 0.3 Mpa. 3. Close the air valves; set the smoke barrier to 1/3 of its opening degree ； 4. Blow steam into the furnace chimney until steam is seen ； 5. Light the ignition rod and place it at the upper end of the burner ； 6. Open the gas burner manual valve ； 7. After lighting, remove the ignition rod and extinguish the fire ； 8. Adjust the gas flow rate, damper settings, and smoke baffle opening ； 9. Adjust the furnace outlet temperature according to the regulations. II. Requirements: 1. The preparatory work must be thorough, including shutting down all burners and manual valves, removing condensate and water from the system’s gas, expelling air, and preparing the ignition rod as well as the light diesel fuel for ignition ； 2. The burner manual valve should be opened slowly ； 3. At the beginning of ignition, manually adjust the gas volume and use symmetrical burners ； 4. To adjust the burners, it is necessary to ensure multiple burners, short flames, even flame distribution, and flames that do not touch the furnace tubes ； 5. Generally, two people work together to ignite it. Question 9: How to handle sudden power outages. I. Steps: 1. Reduce the temperature at the outlet of the heating furnace ； 2. Emergency start of pump and air cooling ； 3. Adjust the high and low liquid levels and pressure in a timely manner ； 4. Closely monitor the reactor bed temperature; overheating is strictly prohibited ； 5. Product sampling and analysis; if it fails the standards, it is sent back for processing or discharged through the oil waste line. II. Requirements: 1. Reduce the temperature of the heating furnace to around 300°C ； 2. Maintain a low liquid level for both high and low pressure levels, with pressure staying within normal ranges ； 3. When starting each pump and air cooler, it is necessary to follow the startup procedures strictly. Question 9: What emergency measures should be taken if the supply of fresh hydrogen for hydrogenation is interrupted? Steps: 1. Close the hydrogen valve of the high-pressure tank ； 2. The heating furnace shuts down ； 3. Cut off the feed ； 4. Maintain gas circulation. II. Requirements: 1. Reduce the reactor temperature to 200°C in order to minimize hydrogen consumption and pressure loss ； 2. Gas flow through the catalyst bed must be maintained throughout the process to prevent catalyst coking. Question 10: What measures should be taken if the hydrogen feed pump fails? Steps: 1. Switch the distillation process to a closed-loop cycle to maintain the liquid levels in various sections ； 2. Cool the hydrogenation heater to 280°C and maintain a single-pass flow through the bed of the hydrogenation reactor ； 4. Contact the plant dispatch and maintenance team to carry out emergency repairs on the pumps. II. Requirements: 1. The distillation section shall be operated in accordance with the process requirements, waiting to be integrated into the hydrogenation process ； 2. The processing volume can be appropriately reduced ； 3. Strictly prevent coking of the hydrogenation catalyst. Question 11: Methods for dealing with high dry point of gasoline 1. Steps: 1. Reduce the temperature at the top of the tower ； 2. Reduce the bottom temperature of the tower ； 3. Reduce the feed temperature ； 4. Enhance dehydration in the flow tank ； 5. Increase the operating pressure of the tower ； 6. Appropriately increase the return flow rate. II. Requirements: 1. The feed temperature at the top and bottom of the tower must not exceed the process requirements ； 2. The pressure in the tower must not exceed 0.3 MPa ； 3. The reflux ratio shall not be greater than 0.25. Question 12: How to deal with overheating in the hydrogenation bed? 1. Reduce the reactor inlet temperature ； 2. Stop feeding, the compressor continues to cycle ； 3. The heating furnace shuts down ； 4. If the temperature continues to rise, stop supplying hydrogen, reduce the pressure, shut down the circulating hydrogen compressor, and open the emergency vent valve. After venting is complete, introduce nitrogen to maintain a positive pressure. II. Requirements: 1. The reactor inlet temperature should be reduced to 270℃ ； 2. Try to increase the circulation volume of the circulating compressor as much as possible ； 3. If the temperature continues to rise, more steam can be introduced into the heating furnace, and the smoke baffle can be opened. Question 13: How to adjust when the flash point of refined diesel is not up to standard? I. Steps: 1. Increase the feed temperature for distillation ； 2. Strengthen dehydration in the reflux tank ； 3. Increase the bottom temperature of the tower ； 4. Increase the top temperature of the tower ； This post was last edited by qlasd on 2009-4-4 14:45.]

Given that your specialty is diesel and gasoline hydrogenation, could you please provide some information on the situation regarding diesel and gasoline hydrogenation at CNPC? Thank you.