Handling of shutdown incidents in the recycle hydrogen compressor of hydrogenation units

Shut down the furnace, discharge waste hydrogen, or use emergency pressure relief to control the bed temperature; monitor areas where high pressure might leak into low pressure areas... The rest can be dealt with gradually – avoid creating vacuum conditions and ensure the tanks are not filled to capacity

Position Title: Shift Leader 1. Immediately report the shutdown of the cyclohydrogen compressor to the dispatch center and the unit. 2. And organize personnel at the relevant positions to handle the accident. Job Title: Diesel Operator – Operational Tasks. Task 1: Verify indoors whether the emergency pressure relief shut-off valve at 0.7 MPa/Min opens in an interlocked manner ； Whether the cut-off valve of the F-101 reaction feed heater, the electric valves at the inlet and outlet of the recycle hydrogen compressor, and the anti-surge electric valve are closed. For internal operations, change the heating furnace for feeding the F-101 reaction and the emergency cooling hydrogen control valve to manual mode and shut them down; also inform external operators to start the cycle hydrogen compressor’s crank operation based on the on-site conditions, for at least 60 minutes. For internal control, use the control valves of the new hydrogen compressor labeled “One Return One” and “Two Returns Two” to adjust the amount of supplementary new hydrogen, reducing this amount to half of its level before shutdown or shutting down the compressor altogether. Internal operator 1: Notify the external operator to switch the product diesel to a short-cycle distillation hot oil system, gradually reduce the outlet flow rate of reaction feed P102 to 60-70% of the design capacity, and coordinate with the upstream and downstream units to stop fresh feed in order to reduce the reaction heat in the system. Internal operation 2:5 – Control the levels of hot high and cold high fluids properly to prevent high pressure from leaking into the low pressure system. For internal operation 26, carefully monitor the reactor temperature; if the reaction temperature stops rising, reset the emergency pressure relief valve and slightly open the waste hydrogen discharge valve to maintain gas flow in the bed. If the temperature cannot be controlled or if the temperature of any reactor bed exceeds the set value, cut off the supply of hydrogen and continue to relieve pressure through the emergency pressure relief valve. Internal operation 17: When the system pressure drops below 4.0 MPa, stop the feed water pump P-103. Ensure that the outlet main valve and flow control valve of this pump are closed. Be careful not to let the liquid level in the feed water tank reach its maximum; in such cases, the level control valve for the tank can be closed. Internal Operation 18: If the top reflux in the distillation system cannot be maintained, shut down the two reflux pumps P202/P204 based on the liquid level conditions. Internal Operation 29: When the bottom temperature of hydrogen sulfide stripping tower C201 is below 150°C, stop steam injection at the bottom of tower C201, close the flow control valve for the stripping steam in C-201, and direct the superheated steam to waste gas discharge at the outlet of reboiler F201. For Internal Operation 2 10, if the reaction temperature rises sharply or a fire occurs, the pressure in the reaction system is reduced to 1.0 MPa; then, the utility department is contacted to supply nitrogen at 2.5 MPa to purge the reaction system. If nitrogen at 2.5 MPa cannot be supplied, the pressure is lowered to 0.7 MPa, and nitrogen at 0.7 MPa is used for purification. Internal Operation 1: Position Name – Diesel External Operation. Operational tasks: At Location 1, verify whether the emergency pressure relief system is activated at a rate of 0.7 MPa/Min, and check if there is any sound indicating pressure relief. If the system is not activated, press the on-site pressure relief button; if that button fails to function, then activate the backup emergency pressure relief valve to relieve pressure. Outdoor Operation 1/2: Verify on-site whether the main fuel cut-off valve of the reaction feed heater F-101 is closed, and also close the valve upstream of the main fuel control valve. Thereafter, turn off some of the continuously burning lamps as needed, leaving a certain number of them lit (after the main steps have been completed). For external operation 2 and 3, establish a short-cycle flow for the fractionated hot oil; direct the naphtha to the unqualified stream, close the manual valve for diesel output from the unit, and then close the manual valve at the inlet area upstream of the diesel hydrogenation unit. For external operation 4 and 4, shut down the circulator, close the manual valve upstream of the cold hydrogen control valve, close the valve located near the wall of the hydrogen sulfide stripping tower C-201 on the stripping steam line, open the drain valve of the steam flow control valve, and direct the superheated steam from the reboiler F201 to the vent. During external operation cycle 5 5, if the circulator stops, quickly open the vent valve for the steam entering the turbine, close the steam inlet valve of the turbine, and divert a small amount of steam to the vent. Outdoor Operation 2 6: Manual valves for the inlet and outlet of the cyclohydrogen compressor, as well as the anti-surge line. External operation 2: Steam at the top of D-501 is diverted to vent. For outdoor operations 5 8, verify that the isolation valve and flow control valve on the main outlet pipe of the injection pump are closed, and close the manual valves upstream of them as well ； Stop all pump injections, and close the outlet manual valves of each injection pump. Operator 2

– Report to the workshop supervisor and company dispatch team – Gather the personnel on duty and activate the \"Emergency Response Plan for Shutdown of the Circulating Hydrogen Compressor C1001 in the Hydrocracking Unit.\" Assign tasks to the relevant personnel:
Reaction unit: Ø Shut down the reaction feed pumps P1001A/B via interlock. Ø Shut down the furnace via interlock associated with F1001. Ø Close the manual valves in front of the main burner of F1001. Ø Once the reaction temperature drops to 150°C and no further temperature rise occurs in the catalyst bed, shut down the feed water pump P1002. Ø Monitor the level of high-pressure liquid closely to prevent overfilling and pressure surges.
Distillation unit: Ø After the feed pumps stop operating, divert the tail oil to another route. Ø Reduce the output volume of each product as necessary. Ø Redirect each product to the circulation line as appropriate. Ø Maintain the pressures and levels in each tower.
Note: Avoid triggering the low-flow interlock in the distillation heater F2001. Investigate the cause of the shutdown of C1001; once the fault is resolved, start up the C1002A/B reaction systems and pressurize them to 2.4 MPa before restarting C1001. The hydrogen circulation pump cannot be restarted; the distillation section is in short-cycle operation, and the entire reaction process has come to a halt.
Reaction plant operator: Ø The emergency low-speed pressure relief valve XCV3112 activates automatically at a rate of 0.7 Mpa/min. Ø Ensure that the electric valves at the inlet and outlet of the hydrogen circulation pump are closed, and that the anti-surge valves are fully open. Ø Stop the feed pump and confirm that the interlock related to XCV3106 is activated. Ø Ensure that the feed furnace is shut down via its interlock system. Ø Close the electric valves MV3101E/MV3101F at the outlets of P1001A/B. Ø Close the pilot light isolation valve XCV3103. Ø Fully open the flue dampers. Ø When the liquid level drops too low, close the manual valve connecting the reaction vessel to the distillation unit. Ø Once the system pressure drops below 0.07 MPa, the emergency low-speed pressure relief valve XOV3112 closes. Ø Fill the system with N2 for protection.
External reactor plant operator: Ø The emergency low-speed pressure relief valve XCV3112 activates automatically at a rate of 0.7 Mpa/min. Ø Stop P1001A/B (see equipment operation procedures). Ø Close the manual valve in front of the main burner of reactor F1001. Ø Shut down the raw material feed pumps in the tank area according to the procedures, and close the valves used to receive diesel into the tanks. Ø Open the steam traps and steam vent valves set at 3.5 Mpa. Ø Open the steam traps and steam vent valves set at 1.0 Mpa. Ø Close the inlet valve of the turbine. Ø Close the outlet valve of the turbine. Ø Turn off all burners in the heating furnace. Ø Fill the system with N2 for protection.
Internal distillation plant operator: Ø After the feed pump stops operating, divert the residual oil elsewhere. Ø Reduce the output volume of each product as appropriate. Ø Adjust the circulation lines for each product as necessary. Ø Maintain the pressure and liquid level of each tower. Outside operation post: Ø Put into use the large-orifice plate flow meter in the tail oil discharge unit, and add air cooling for the tail oil. Ø Activate the circulation lines for each product. Ø Close the valves on the output lines for each product. Shift supervisor post: Ø If the 0.7 Mpa/min emergency pressure relief valve does not open, manually activate it. Ø Coordinate with various posts to check the handling situation at each position

One, pay attention to the high liquid level. Second, pay attention to the temperature rise in the reactor bed; if it becomes too high, emergency pressure relief can be employed. Third, decide whether to shut down the operation or restart it immediately based on the status of the cycle hydrogen compressor