How to operate a delayed coking unit during a power outage

In the case of a short-term power outage (transient power loss), close the pump outlet valve. Once power is restored, restart the pumps in the following order: (1) Heating furnace area: feed water pump, radiation pump, seal oil pump, induced draft fan, and flue gas exhaust fan. (2) Fractionation unit: feed pump, wax oil pump, tower top reflux pump, intermediate stage pump, gasoline pump, sewage pump, diesel pump, deaerator water pump. Coke tower position: Start the pump in a timely manner or switch to a backup pump based on production conditions, to ensure continuous operation. Pneumatic compressor station: If the compressor stops operating due to power fluctuations, activate the flare system promptly to maintain system pressure. In the event of a prolonged power outage, the heating furnace should be shut down immediately; natural ventilation should be used, and if necessary, the flue dampers can be adjusted to allow more airflow. (2) Treat it as an emergency shutdown. (3) Inform the dispatch team to stop feeding raw materials in, and clean the lines promptly. (4) Use a steam pump to remove all the oil from the device.

This post was last edited by jnlxcyg on 2009-5-28 09:47. Here is our plan for dealing with power fluctuations: Phenomenon: (1) Flickering lighting； (2) Some pumps and air coolers are shut down ； (3) The reflux sections of the fractionation system and stabilization system are interrupted, causing the top pressure to rise and the side-line temperature to increase. Handling: (1) Team leader: a. Immediately report to the dispatch team, workshop duty personnel, and relevant workshops to determine the cause. b. Make overall arrangements and direct the entire class in handling it. (2) Reaction operator: a. Check the feed rates for the four feed lines of the heating furnace. If a downward trend or interruption in the feed rate is detected, quickly increase the water injection volume; depending on the operation of the radiation pump, reduce or completely close the fuel gas control valve. This can help lower the pressure in the gas tank, preventing the flame of the pilot light from becoming too strong, which in turn would avoid further increases in furnace temperature and prevent coking of the furnace tubes. Notify the site of Reaction 2 to close the fuel gas valve of the coker as appropriate. After the radiation pump is restored, the temperature is increased gradually to resume production. b. Check the water injection volume of the heating furnace. If there is a downward trend or interruption in the water injection flow rate and pressure, immediately inform Operator 3 to go to the site to start the high-pressure water injection pump; at the same time, notify the main operator in charge of distillation to increase the feed volume to the four feed lines of the heater accordingly, thereby raising the feed pressure of the heater. (This assumes a stable feed rate of four streams and no abnormalities with the radiation pump.) If both the feed rate and the water injection volume are interrupted, the main operator responsible for the reaction should close the fuel gas control valve completely and reduce the pressure in the gas tank. At the same time, they should inform the assistant operator responsible for the reaction to immediately start the high-pressure water injection pump; depending on the status of the radiation pump, they should also instruct the assistant operator 2 to shut off the fuel gas valves of the coking furnace on site. c. Check whether the ESD protection is interlocked for the blast furnace blowers and exhaust fans, as well as whether the dampers in the flue or air ducts have self-protection interlocking. Notify to go to Site 4 for inspection to check the operation status of the blowers and induced draft fans, as well as whether interlocks are in place in the flue ducts and air ducts. When the situation returns to normal, the chain is restored, and it is instructed to start the blowers and induced draft fans at Site 4. d. Check the top pressure, bottom temperature of the coke tower, and the temperature at the furnace outlet. If there is overpressure at the top of the coke tower, immediately notify the shift leader to vent the fractionation system. If there is pressure buildup at the furnace outlet, immediately inform Operator 2 and 3 to raise the coke tower by 10 meters. If a tower that has been preheated is available, switch to it; if no such tower is available, set the four-way valve to position C and use the emergency pressure relief line to direct the flow to the cold tank discharge system. The old tower should be handled according to the normal cooling procedures for coke. Operator 4 should check whether the downstream path is unobstructed. If everything is normal, notify the personnel responsible for operations 3 and 4 to go to the site to check whether there are any abnormalities in the positions of the four-way valves and electric isolation valves on the 10-meter platform of the coke tower, as well as whether the indicator lights are functioning correctly. f. If nothing is abnormal in the above items, check whether the circulation pump at the bottom of the vent tower is operating properly; contact the assistant operator to go to the site for inspection and start the pump promptly. (3) Reaction Assistant Operator: Upon detecting voltage fluctuations or upon receiving notification from the main operator, Reaction Operator 2 should immediately head to the fuel gas valve of the heating furnace, while Reaction Operator 3 should go to the high-pressure water injection pump. They are to monitor the operation of the water injection pump and report to the main operator; in case of any abnormalities, they must shut down the pump immediately. Reaction Operator 4 should then go to a location 10 meters away from the coke tower, open the main steam valve for Production Tower 1 to prevent sticky oil from flowing back, and subsequently go to the blowers and exhaust fans to monitor their operation and report to the main operator. Reactions 2, 3, and 4 should proceed with the next steps as instructed by the main operator. (4) Fractionation Operator: a. Check the feed rates for the four feeds to the heating furnace. If a downward trend or interruption in the feed rate is detected, check the ESD radiation pump interlock, contact the assistant reactor operator, and once it is confirmed that there are no abnormalities in the seal oil system, restore the radiation pump interlock and inform the assistant operator to start the radiation pump promptly (specify which pump should be started when giving the instruction). b. Close the crude gasoline flow control valve at the absorption tower, and close the level control valve of D-4003 to prevent high pressure from leaking into the low pressure system. c. Control the levels of D-4001, D-4018, and D-4003 to prevent overfilling. d. Check the pressure at the top of the distillation tower. In case of overpressure, promptly inform the assistant operator to open the fractionation flare valve. e. Check in order of priority: the flow rates at the inlet and outlet of the crude oil pump, deaeration water pump, wax oil pump, top circulation pump, intermediate reflux pump, diesel pump, air-cooling fan, gasoline pump, and sulfur-containing wastewater pump, as well as the amount of fluid drawn out from each stage and the amount returned to the tower. In the order mentioned above, sequentially inform the assistant operator to start the corresponding pump for intentional shutdown. (During the processing, remain calm and steady; confirm that there are no issues with the pump starting, and then contact the assistant operator to start the next pump that is to be shut down temporarily.) f. Once all pumps are functioning properly, promptly check whether there are any abnormalities in the various process parameters of the distillation system, and make adjustments to production as needed. (5) Fractionation assistant operator: a. Upon detecting voltage fluctuations or upon receiving notification from the main operator, immediately head to the oil sealing pump. If it is detected that the oil sealing pump has stopped operating, start it immediately. b. Follow the instructions of the chief operator to sequentially start the heating furnace radiation feed pump, crude oil pump, deaerator water pump, wax oil pump, top circulation pump, intermediate reflux pump, diesel pump, air-cooling fan, gasoline pump, and sulfur-containing wastewater pump. Before turning on the radiation pump, be sure to check whether the seal oil pipeline and the cooling water pipeline are in good condition. When starting the pump, first close the pump outlet valve and press the \"Stop\" button; then start the pump. Once the outlet pressure and current have stabilized, slowly open the pump outlet valve. When starting the backup pump, the outlet valve of the operating pump must also be closed to prevent oil from flowing back. To enable air cooling, simply press the “Stop” button and then start it up. c. After the operator confirms that there are no abnormalities with the pumps, a prompt on-site inspection of the distillation system should be carried out to verify whether the opening degrees of the control valves are normal and whether the process flow is correct. (6) Compressor: a. Check the DCS and ESD screens for the inlet and outlet pressures, flow rates, and anti-surge control settings of the compressor. If any abnormalities are detected, check whether the air compressor is interlocked. Run to the site promptly to verify whether the interlocks of the air compressor have been activated [the inlet and outlet valves of the air compressor are closed, a flare is in use, and the anti-surge valve is open]. (a) In cases where there is an assistant operator for the compressor, after a power fluctuation, the assistant operator immediately goes to the compressor site, while the main operator monitors the DCS and ESD systems from the control room. b. Once it is confirmed that the compressor interlocks can be restored, the supervisor is informed; the ESD system then restores the compressor interlocks (in cases where there is no assistant operator, the supervisor is instructed to restore the compressor interlocks from the control room). Start the compressor at low frequency, and fully close the fractionation flare valve. In the event of a prolonged power outage, shut down the system using the emergency shutdown procedure.

Thank you for your reply. Could you tell me how your ESD systems are interlinked, and how they respond in the event of an accident?

There are two scenarios for ESD interlock: the tripping of the turbine oil pump (which is an electric pump) leads to the interlock of the compressor； Insufficient inlet rich gas flow causes the compressor interlock ；

The general approach to dealing with power outages is to prevent oil from coking and blocking the pipelines, as well as to ensure the safety of the facility. It’s troublesome when there’s a widespread power outage; we’ve experienced full-scale outages across the entire plant, and in such situations we’re basically helpless – there’s even no steam available.

Listen to the steam throughout the whole length; just leave it to fate. I remember another time, in the dead of winter when the temperatures were extremely low, it stopped working. Calling to the heavens yields no response; calling to the earth yields no reply. Powerless, filled with fear.

Workers on the 6th and 7th floors, how did you handle this situation? After the call was made, was it still possible to inject steam or water for cooling into the coke tower? Were there any problems that arose? Thank you

Reply to 8# Dancing Wind001: Methods for dealing with power outages. 1. Methods for handling a complete power outage: ① A complete power outage refers to the loss of power in all 10KD, 380D, and 220D power grids. After a complete power outage, all compressors and pumps stopped operating, and the plant was put into emergency shutdown mode. After the power loss, the backup power supply of the DCS switched on automatically. The pressures of steam, air, gas, etc. gradually decreased, but did not drop to zero immediately. The main operator of the furnace quickly closed the steam control valve, while the shift leader promptly switched to using excess steam for cooling. The assistant operator rushed outside to shut off the valves upstream and downstream of the furnace’s fuel control valve, fully opened the flue dampers, and opened all the natural draft doors in order to rapidly cool down the furnace chamber. The other operator quickly starts the steam reciprocating pump when there is excess steam pressure, using it to replace the radiation pump in order to transfer the hot oil that is forming coke inside the furnace tubes to the coke tower, thereby reducing the temperature of those tubes. At the same time, the main furnace operator shuts down the other steam-using control valves, informs the dispatch center to supply steam only to the coking unit, cuts off the supply to other steam-consuming devices, and then quickly works together with the team leader to shut down the main equipment: first by closing the inlet and outlet valves of the radiation pump, then stopping the compressor, and finally shutting down the other pumps. Then wait for the call ； In the event of a short-term power outage, the counter-rotating pump should be started immediately to initiate circulation. Once a new column meets the switching conditions, the flow should be directed to the feed inlet of that new column; the oil should not be routed through the make-up line to the distillation column. After power is restored, the furnace should be ignited to raise the temperature, and feed should be supplied to the production column following the normal startup procedures. If the power outage lasts for a long time and temperatures drop everywhere, it is necessary to wait until steam supply is restored, then shut down the system in accordance with the prescribed sequence before restarting the operation by feeding oil again. ②Fractionation and subsequent unit operations: After a power outage, the pressure in the general air system drops rapidly. The operator then checks the temperatures and pressures displayed on the DCS, and goes out to adjust the various control valves (which can be controlled via auxiliary lines). First, Fu Cao closed the inlets and outlets of the moving equipment and set the power switches of the equipment to the off position. To maintain the liquid levels in various towers and vessels, he closed the valves for the discharge of oils, the valves for discharging sulfur-containing wastewater, and the valves for gas discharge, thereby trying to keep the pressures at various points stable and thus creating a good foundation for resuming operations once power is restored. 2. Procedures for dealing with a power outage of 10KD high-voltage power while 380V and 220V powers remain operational: The compressors, radiation pumps, and high-pressure water pumps in the coking unit all rely on 10KD power; therefore, when this power is interrupted, these units cease to operate. The steps to take are as follows: ① For the heating furnace: The operator should reduce the furnace temperature by lowering the gas control valve and the opening degree of the burner valves, increase the amount of water injected to prevent the furnace tubes from overheating, reduce the volume of convective feed, and coordinate the operations of the furnace as a whole. Adjustments should also be made to C-1001/A and B. The operator must act quickly by shutting down the radiation feed pump and activating the steam reciprocating pump to replace it in feeding the furnace, thereby resuming production. Operations should be adjusted accordingly, but the overall processing volume should be kept at its minimum level. Once power is restored, start P1002; depending on the situation, preheating may be necessary before starting it, and the steam pump should be turned off after the radiation pump starts operating. ②Distillation stabilization: Redirect the excess vapor to the flare, adjust the distillation pressure to maintain normal system pressure, control the level of the distillate properly to prevent it from becoming either too full or too low, and ensure that the three-tank cycle is carried out in a stable manner to maintain system pressure and level. ③Stop defocussing. 3. Procedures for handling a 380V low-voltage power outage: ① Complete shutdown of 380V low-voltage power: In this case, all low-voltage pumps, fan air-cooling motors, etc. will stop operating, while the compressor P1002 will continue to run; the system shall be handled as an emergency shutdown. ②If there is a power outage for one of the 380D units, the motor of the other unit should be started immediately; after that, the pump should be shut down and the backup pump activated. In the event of air-cooling failure, production can only be maintained by reducing the output volume, and all relevant personnel must adjust their operations accordingly. 4. Methods for dealing with instantaneous voltage fluctuations: (1) Methods for handling 10 KD voltage fluctuations: ① If P1002 stops operating momentarily, first reduce the temperature in the furnace, then increase the water injection volume; subsequently, the main operator makes adjustments, while the assistant operator closes the inlet and outlet valves of P1002 before restarting it. ②If the injection pump or compressor stops operating, start the injection pump immediately; redirect the rich gas to the flare system, use the absorption and stabilization system to maintain pressure, and operate the three towers in a cyclic manner. Meanwhile, control the top pressure properly. Then close the inlet and outlet valves of the compressor first, open the compressor’s flare valve, and subsequently start the compressor following its startup procedure. Stable adjustment operation. ⑵Principles for handling power outages: ① Prevent the D-1001 tank from becoming full. ②The system does not experience overheating or overpressure. ③It is crucial to ensure the proper operation of the flue gas heating furnace, as well as units P1002 and P1001. Special attention should be paid to the maintenance of the hot oil pumps to prevent oil leakage from the end-face seals, which could lead to fires.