Emergency Plan for Startup Accidents of Catalytic Units

Chapter 5: Emergency Procedures for Equipment Incidents 1. Operating Principles: For various reasons, the equipment may encounter emergencies such as water supply interruptions, steam supply disruptions, power outages, air supply disruptions, as well as fires and explosions. In the event of such emergencies, it is necessary to remain calm and composed, make accurate analyses and judgments, take decisive action, and ensure unified command. Different positions must work closely together; while prioritizing safety, efforts should be made to protect the equipment and prevent the incident from spreading, following the normal shutdown procedures as much as possible. 2. Several common accident handling procedures 2.1 Procedure for shutting off feed in case of a reaction issue 2.1.1 Reaction unit: (1) Activate the feed safety interlock to shut off the feed to the reaction vessel. ⑵Check the operation of each pressure relief valve, and close the manual valve before shutting down the feed nozzle. ⑶Check whether the raw material accident return line and the slurry accident return line are unobstructed. ⑷Closely monitor changes in system pressure, pressure difference, temperature, inventory, density, and pressure drop, make timely adjustments to maintain proper fluidization in both reactors. ⑸Analyze the reasons, resolve the accident as soon as possible, reorganize the feeding process according to the startup procedures, and resume production. ⑹Burn oil is injected into the regenerator bed to maintain the regenerator bed temperature at no less than 550°C. 2.1.2 Distillation unit: Processing steps and principles: (1) Establish three circulation paths for crude oil, reprocessed oil, and slurry (open-loop circulation). ⑵Crude gasoline is discharged directly from the unit; for V—202A,B, pay attention to the liquid level and enhance water separation. ⑶After the top circulation pump and the intermediate circulation pump are evacuated, stop the pumps and close the outlet valves. ⑷Use the top cold reflux to control the temperature of T–201 at no more than 110°C. ⑸Adjust the heat exchange capacities of E—210A and B so as to maintain the bottom temperature of T—201 at around 300°C and the temperature of the reprocessed oil at around 250°C, thereby enabling the reprocessing of feedstock and the reprocessing of oil slurry as soon as possible after feed is reintroduced. ⑹Adjust the amount of discharge to properly control the level of T—201 liquid. ⑺After resuming feeding to the reactor, operations are resumed in coordination with other teams. ⑻If feeding cannot be resumed for an extended period, it shall be treated as a shutdown. 2.1.3 Absorption stabilization post: processing steps and principles ； ⑴Notify the pneumatic press operator to adjust the inlet valve of the pneumatic press. ⑵Remove the heat source from the middle section and close the valves for the output of stabilized gasoline and liquid hydrocarbons. ⑶Maintain pressure in the system. ⑷Close the V—302 water cut-off valve, and close the wash water valve assemblies at the shut-off valves for T—201, V—302, and V—813. ⑸Establish a three-tower gasoline cycle. At this time, stop the circulating oil return pump in the middle section of tower T-301, close its outlet valve, or use the method of shutting down the pump to maintain normal levels of the various liquids. 2.1.4 Procedures and principles for the two-machine operation post: (1) The main fan and booster must operate properly, with air supply not being interrupted. ⑵Contact the reaction shift to shut down the compressor, and vent the rich gas to the flare. ⑶Contact the air compressor station to maintain the air pressure at no less than 0.4 MPa (gauge). 2.2 Principles for Handling Emergency Power Outages in the Facility 2.2.1 Reaction Unit ⑴ Emergency handling steps: Step 1: Activate the automatic protection system to shut off the feed, disconnect the two reactors, and cut off the main air supply (activate the fan’s automatic protection system as appropriate); open the double-acting slide valve and the oil-gas butterfly valve to relieve pressure in the settler. Operation 2: Shut off the feed valve before closing the nozzle, check the operation of the automatic protection mechanism; open the preheating valve of the nozzle, adjust the emergency return flow process for crude oil and slurry, and close the primary and secondary main air cut-off valves. Note: Depending on the conditions of steam and air pressure, close the first shut-off valves at each steam, air, loosening, atomization, and reverse-blowing point from top to bottom, and send the oil slurry back to the reprocessing line. ⑵Restore power supply in a short time; organize feeding and adjust operations depending on the condition of the main fan. ⑶In the event of a prolonged power outage, coordinate with the fractionation unit to handle crude oil, reprocessed oil, added oil slurry, and oil slurry lines. ⑷If the settler removes all oil and gas over a period of more than 30 minutes, a blind flange can be installed on the main oil and gas pipeline and the steam seal can be switched; however, if steam supply is stopped at the same time, it is not possible to install a blind flange on the main oil and gas pipeline or switch the steam seal. 2.2.2 Fractionation unit: (1) Close the outlet valves of all pumps, shut off the bottom steam valve of tower T-201 and the bottom stripping steam valve of T-202, and supply water to T-201. ⑵After power is restored, start the pump to establish a three-way circulation first. ⑶Cooperate with other position adjustment operations. ⑷If steam is shut off simultaneously and power and steam supply cannot be restored for an extended period, oil shall be drained provided that the temperature at the bottom of T-201 and in the heavy oil pipelines does not exceed 100°C. 2.2.3 Absorption stabilization position: (1) Set the instruments to manual mode, and close the pressure compressor to prevent compressed rich gas from entering the stabilization manual valve. ⑵Guantan T-304, V-303 pressure-controlled manual valves for system pressure retention. ⑶Turn off the stable gasoline; open the valve for liquid hydrocarbons to leave the unit. ⑷Close the outlet valves of all pump shutdown valves. ⑸Close the V—302 and V—813 water cut-off valves, and close the wash water valve. ⑹Regarding the gas release to atmospheric pressure and the power hand valve. ⑺Close E—804 heating steam manual valve, main hydraulic control and auxiliary line. ⑻After power is restored, first establish a stable three-column gasoline cycle, or maintain the respective liquid levels, and proceed according to the normal startup procedures. 2.2.4 Dual-machine operation ⑴ Close the electric butterfly valve at the main fan outlet, and open the anti-surge valve of the main fan. ⑵Close the inlet and outlet valves of the pressure compressor, and vent the rich gas to the flare. ⑶After power is restored, start the main fan following the specified procedures: first evacuate the air, and then connect the main air flow to the regenerator. ⑷After the reaction and fractionation systems are operating stably, start the air compressor according to the specified procedures to supply compressed rich gas to the absorption stabilization system; pay attention to removing condensate from the rich gas before starting the compressor. 2.3 Principles for handling steam shutdown in the unit 2.3.1 Reaction section a. When the steam pressure inside the unit is below 0.3 MPa (gauge), close the feed isolation valve and switch to the emergency return T—201 process; establish a three-way circulation system, with steam being supplied to R—101/A and D. b. First, close the regeneration slide valve to increase the positive pressure difference between the two vessels (increase the pressure in R—101B and decrease it in R—101C). Transfer the catalyst from the settler to the regenerator; then close the raw catalyst plug valve to achieve single-vessel fluidization. Reduce the main air flow based on the bed temperature in order to minimize catalyst loss, and inject combustion oil according to the bed temperature to maintain it at around 500–550°C. c. If the steam pressure does not recover within half an hour, treat it as a shutdown. d. Emergency steam shutdown: ⑴ Activate the automatic shut-off system to cut off feed, close the raw material stop valve and regeneration slide valve, open the double-acting slide valve, open the oil-gas butterfly valve to relieve pressure in the settler, and close the steam inlet and outlet valves. ⑵Before closing the nozzle, shut off the feed valve; open the nozzle preheating valve to establish the emergency return-to-column procedure. ⑶After completion, turn off all steam-using points from bottom to top, including accident shutdown, atomization, purging, cooling, sampling, stripping, loosening, and anti-coking functions. ⑷If steam supply cannot be restored quickly, treat it as an emergency shutdown. 2.3.2 Fractionation Unit ⑴ Establish three circulation paths for crude oil, reprocessed oil, and slurry; close the valves for stirring steam and stripping steam. ⑵Use cold reflux to keep the tower top temperature at no more than 110°C. ⑶The crude gasoline is sent directly to alkaline washing, with the V—202 liquid level controlled at 50%. ⑷Gradually reduce the amount of feed oil while maintaining the bottom of the tower temperature and the reprocessed oil temperature. ⑸If the steam pressure does not recover within half an hour, proceed with normal shutdown procedures. ⑹Emergency steam shutdown: Maintain the three-way circulation; if recovery is not possible for an extended period, drain the oil and vent any remaining heavy oil. 2.3.3 Absorption stabilization station ⑴ After stopping the air compressor, close the manual valve for compressing rich gas from the compressor into the stabilization system. ⑵Close the T—304 and V—303 pressure control valves to maintain system pressure. ⑶Close the valves for stable gasoline and liquid hydrocarbons leaving the unit. ⑷Close the V—302 and V—813 water cut-off valves, and close the wash water valve. ⑸Turn off E—804 heating steam, ethanolamine circulation, or stop the pump. ⑹Establish a stable three-tank cycle for gasoline, or stop the pumps to maintain each liquid level. ⑺If the steam pressure does not recover within half an hour, proceed with normal shutdown procedures. ⑻Emergency steam shutdown: Handle it as a normal shutdown. 2.3.4 Dual-machine position ⑴ The main fan operates normally to maintain air supply. ⑵Stop the air compressor, close the inlet and outlet valves of the compressor, and open the rich gas flare. 2.4 Principles for shutting down water treatment in the plant 2.4.1 Shutting off fresh water: The fresh water used in this plant is primarily for general domestic use and as makeup water for the cooling tower. When fresh water supply is stopped or the pressure of fresh water is below 0.01 MPa (gauge), the valve connecting the circulating water to the fresh water line can be opened to introduce circulating water into the fresh water line; at this time, the main valve for fresh water entering the system as well as all the branch valves should be closed. 2.4.2 Shutdown of circulating water: The circulating water in this unit is primarily used for cooling the air compressors, various coolers, and the main fan; it constitutes the main source of water necessary for the proper operation of this unit, and its supply must not be interrupted arbitrarily. If the supply of circulating water to this unit is interrupted, the system’s circulating water should be diverted into this unit’s circulation system. In such cases, the reaction system should operate at reduced capacity, and the return valves of all cooling equipment should be closed in order to maintain proper cooling of the main fan. When the pressure of the circulating water is too low to ensure normal operation, the feed to the reaction system should be stopped for processing. In the event of a prolonged interruption in water supply, emergency shutdown procedures should be followed. 2.4.3 Shutdown of deoxygenated water: The deoxygenated water used in this unit is primarily for waste heat recovery. When shutting down the deoxygenated water system, the inlet and outlet valves for this water should be closed; the heat exchange coils should be fed with protective steam or superheated steam, which should then be directed to the vent. Operations should be carried out based on the temperature drop in the regenerator bed. If recovery is not possible over an extended period, the system should be shut down as per standard procedures. 2.4.4 Stop both fresh water and circulating water simultaneously, and handle it as an emergency shutdown. 2.5 Principles for shutting down air supply in the device 2.5.1 Shutting down non-purified air: The non-purified air used in this device is primarily for various loose connections in the reaction system and for the fluidization and transportation of catalysts; when this air supply is shut off, steam can be used to replace it at those loose connections. 2.5.2 Stop the purification air supply: ⑴ When the pressure of the purification air is below 0.35 MPa (gauge), promptly contact the dispatch team and the air compressor station to increase the air pressure. ⑵When the pressure of the purge air is below 0.3 MPa (gauge), manually operate each butterfly valve to appropriately reduce the pressure in the two units; ensure that the storage volume and circulation volume remain stable, and replace the backblast air, fluidization air, and loosening air for the raw material plug valve and single-acting slide valve with steam. ⑶The purge air pressure dropped to 0.2 MPa (gauge), all instruments stopped functioning, and an emergency shutdown was initiated. 2.6 Fire incidents: In the event of a fire in the unit, it is necessary to first determine the location of the fire, try to eliminate the source of ignition, close the connected valves, and control the fire. When the fire becomes difficult to control and poses a threat to the safety of the entire unit, the feed to the reaction process must be stopped immediately, and the oil inside the unit should be removed as quickly as possible. 2.7 Leakage incidents in the facility: When a fault occurs in the gas or liquid hydrocarbon system, resulting in significant leakage, all open flames within the facility must be extinguished immediately. All motorized vehicles, including fire trucks, are prohibited from entering the site. Operators on duty should promptly use explosion-proof or rubber-coated wrenches to close the relevant valves in order to cut off the gas supply and prevent further spread of the gas. People should not stay in areas with high gas concentrations for long periods to avoid gas poisoning; in case of gas poisoning, the affected person must be taken to the hospital for treatment immediately