[Q&A Question 257] 2017.09.15
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This post was last edited by liuquan1100 on 2017-9-15 14:27. [Q&A Question 257] How should circular pumps (centrifuges) be handled during the power outage on 2017.09.15? (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) The answers to the daily questions change, and today’s answers are shown in subsequent questions. For management purposes, if you need to view content from a few days ago, please go through the summary post below. 2017 Q&A Summary Thread (updates have started) http://bbs.hcbbs.com/thread-1657793-1-1.html 2017 Daily Question Summary Thread (updates have started) http://bbs.hcbbs.com/thread-1657794-1-1.html 2016 Q&A Summary Thread (updates completed) http://bbs.hcbbs.com/thread-1597792-1-1.html (Source: Haichuan Chemical Industry Forum)
Close the inlet and outlet manual valves of the circulation pump; after power is cut off, the electric valve will not be able to operate
Shut down the machine, stop the pump, extinguish the furnace fire, and relieve pressure urgently
Quickly close the inlet and outlet valves of the circulation pump, and open the circuit valve. Open the vent valve to relieve pressure and turn off the cooling water. At the same time, quickly start the backup circulator, contact the previous process unit to reduce the flow rate, and maintain the normal temperature of the synthesis tower furnace.
After the circulation pump stops operating, the emergency pressure relief valve XDV2104 opens in sequence to relieve pressure in the system; depending on the temperature rise of the reactor bed, the pressure in the reaction system is reduced to below 2.5 MPa. Due to the shutdown of the circulation pump, the heat generated in the reactor cannot be removed, which poses a risk of the bed temperature getting out of control. Therefore, it is necessary to closely monitor the bed temperature, and if needed, increase the rate of pressure release: open the PV2301 valve leading to the flare on site, close the valve leading to the catalytic cracker, and open PV2301 to accelerate pressure release. While doing so, pay attention to the condition of the flare. If the bed temperature continues to rise, continue to reduce the pressure until it reaches 0.5 MPa, at which point N2 can be introduced from the hydrogen generator.
After confirming that the compressor has stopped operating, first close the secondary-to-primary and primary-to-primary control valves as well as the on-site manual valves and the bypass valves； Move the compressor start button to the lockout position, close its inlet and outlet valves (close the new hydrogen machine first), and open the flare to release the pressure inside the unit.
Confirm interlock; divert medium-pressure steam to vent, divert backpressure steam to vent, close the orbit manual valve, start the booster pump, perform manual shaft rotation, and switch the main seal gas to nitrogen when the pressure is below 0.7.
Confirm interlock; divert medium-pressure steam to vent, divert backpressure steam to vent, close the orbit manual valve, start the booster pump, perform manual shaft rotation, and switch the main seal gas to nitrogen when the pressure is below 0.7.
After the circulation pump trips, close its inlet and outlet valves, open the bypass valve, and relieve pressure from the circulation pump. To prevent the system from overpressuring, shut off the fresh gas valve and open the vent valve to release pressure; control the pressure in the synthesis drum based on the temperature of the catalyst bed to avoid overheating. Coordinate with the previous process to reduce consumption, and quickly activate the backup circulation machine; if no backup circulation machine is available, take emergency shutdown measures.
Shut down the circulator, and close the inlet and outlet electric valves XV-11802 and XV-11801, as well as the anti-surge electric valve XV-11803.