Operating Procedures for the Urea Pump Room

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Operating Procedures for the Urea Pump Room 1. Main Tasks of the Position: Responsible for transporting materials, pressurizing them to the pressure required by the manufacturing process using plunger pumps or centrifugal pumps, and delivering them to various equipment and containers. Ensure that the operating conditions meet the requirements specified in the process parameters. In charge of starting up, shutting down normally, initiating emergency shutdowns, as well as performing routine maintenance on the ammonium carbamate tank, the evaporation and condensation liquid tank, as well as the ammonia pump, monoethylamine pump, diethylamine pump, ammonia water pump, evaporation and condensation liquid pump, and desorption pump. It is also necessary to keep accurate records of all operations. 2. External Communication 2.1. Maintain regular contact with the control room, report in a timely manner on the operation status of the liquid ammonia pump, the primary methanol pump, the secondary methanol pump, and the ammonia water pump, and make corresponding adjustments as required by the control room. 2.2. During startup, shutdown, and abnormal conditions, contact the circulation shift to carry out flushing of certain equipment and pipelines. 2.3. Communicate with electrical and instrumentation systems to reflect issues related to electrical equipment and instruments. 3. Process Parameters 3.1. Pressure ⑴ Inlet pressure of the ammonia pump: 1.7–1.9 MPa; outlet pressure: 20.0–20.6 MPa. ⑵ Inlet pressure of the monoammonium pump: 1.8–2.0 MPa; outlet pressure: 20.0–20.6 MPa. ⑶ Outlet pressure of the dimonoammonium pump: 1.8–2.0 MPa. ⑷ Outlet pressure of the ammonia water pump: 1.8–2.0 MPa. ⑸ Outlet pressure of the flushing pump: 20–25 MPa. ⑹ Outlet pressure of the desorption pump: 0.7–1.0 MPa. ⑺ Outlet pressure of the evaporation condensate pump: 0.4–0.8 MPa. ⑻ Outlet pressure of the steam condensate pump: 0.8–1.0 MPa. 3.2. Liquid Level ⑴ The normal liquid level in the ammonium carbonate tank should be maintained between 25% and 50%. ⑵Level of the secondary tank liquid ≥50% ⑶ Condensate tank: 50–90% 4. Startup, shutdown, and emergency shutdown procedures 4.1. Initial startup 1.1.1. Preparation work 1.1.1.1. Check that all tools, equipment, fire protection measures, protective gear, and reports are available and in good condition. 1.1.1.2. Contact an electrician to check for any issues with the electrical system and interlock devices. 1.1.1.3. Check whether the pump body, pipes, valves, and associated equipment (including instruments) are in good condition. 1.1.1.4. Check the safety valves and safety devices, and open the root valves of each safety valve and pressure gauge. 1.1.1.5. Check the quality and level of oil in the crankcase and transmission, and change the oil or top it up as necessary. 1.1.1.6. Valves in each cooling system draw in cooling water. 1.1.1.7. Open the insulation steam inlet valve of the companion pipe, the insulation valve of the material jacket at the bottom of the synthesis tower, and open the drain valve. 1.1.1.8. Upon receiving instructions from the control room, fill the ammonium carbonate tank and the second metering tank to a 20% liquid level. 1.1.1.9. When pressurizing the circulation system, upon receipt of the instruction, drain the water accumulated in the inlet and outlet pipes of the ammonia pump as well as inside the pump. 1.1.1.10. After receiving the ammonia introduction signal, start the tail suction pump. 1.1.2. Starting the high-pressure ammonia pump 1.1.2.1. Rotate the pump 2–3 times to check whether the connecting parts of the main unit are in good condition. 1.1.2.2. Rotate the oil pump 2–3 times, open the inlet and outlet valves of the oil cooler (they can be opened slightly or later in winter), start the oil pump motor, adjust the oil pressure to the specified value, top up the seal water by starting the seal water pump, and adjust the amount of seal water. 1.1.2.3. Valves to be closed: flush water inlet valve, pump outlet valve, drain valve, drain valve between the two check valves at the pump outlet, standby pump outlet valve, bypass valve, liquid ammonia inlet valve, and reactor bottom inlet valve. 1.1.2.4. Valves to be opened: the pump outlet bypass valve, the valve connecting the circulation buffer tank to the pump inlet main valve, and the pressure gauges located in front of the cut-off valves on the pump body. 1.1.2.5. Slowly open the inlet isolation valve. 1.1.2.6. After receiving notification from the control room, start the pump and simultaneously check whether the pump body and associated equipment are functioning properly. 1.1.2.7. Slowly close the pump bypass valve to gradually raise the pump outlet pressure to 19.67 MPa, and check the operation of the pump and associated equipment. 1.1.2.8. Open the two stop valves at the pump outlet to direct ammonia to before it enters the synthesis tower. 1.1.3. Starting up the No. 1 pump 1.1.3.1. Preheat the pump body with steam condensate 1.1.3.2. Rotate the pump 2–3 times to check that the connecting parts are in good condition and to verify that the auxiliary lines are unobstructed. 1.1.3.3. Rotate the oil pump 2–3 times, open the outlet valve of the oil cooler, and adjust the oil pressure to the specified value. 1.1.3.4. Stop pump preheating. Valves to be closed: Ammonium hydroxide liquid inlet pipe discharge valve, pump outlet isolation valve, high-pressure flushing valve at the pump outlet, 1.1.1.1. water valve, and outlet bypass valve. 1.1.1.2. Valves to be opened: pump outlet valve, pump outlet bypass valve, seal water inlet and outlet valves, to feed methylammonium solution into the pump. 1.1.1.3. Contact the control room, adjust the pump to its lowest speed, start the pump, and use a bypass line to create circulation in order to check whether the pump itself and its associated equipment are functioning properly. 1.1.1.4. Gradually close the bypass valve to apply pressure slowly, while adjusting the pump speed to raise the outlet pressure to 19.6 MPa. 1.1.2. Starting the high-pressure flushing water pump 1.1.2.1. Rotate the pump 2–3 times to check whether the connecting parts are in good condition. 1.1.2.2. Valves to be opened: pump inlet valve, pump outlet bypass valve, and pressure gauge root valve. 1.1.2.3. Valves to be closed: the pump outlet valve, the flushing water valves for each material at the bottom of the tower, and the flushing water valve at the top of the synthesis tower should be closed, in coordination with the circulation team. 1.1.2.4. Start the pump and check whether it is operating normally. 1.1.2.5. Slowly close the outlet valve and pressurize to 25 MPa. 1.1.2.6. Once normal operation is achieved, open the pump outlet valve to flush the material pipelines leading to the synthesis tower one by one, as well as the material pipeline at the outlet of the synthesis tower. 1.1.2.7. After flushing is complete, open the outlet bypass valve, close the outlet valve, stop the pump, and stop the oil pump. 1.1.3. Introduction of three materials into the tower 1.1.3.1. Raise the pressure of ammonia; upon receiving the corresponding instruction, close the discharge valve at the bottom of the synthesis tower, open the drain valve at the outlet of the ammonia preheater, and slightly open the shut-off valve for liquid ammonia entering the tower at its bottom. Control the amount of ammonia by adjusting the outlet valve of the ammonia pump. After being preheated to over 150°C in the preheater, the ammonia is sent into the synthesis tower. As the pressure in the synthesis tower increases and the amount of ammonia rises, the control room will instruct that the bypass line of the ammonia pump be gradually closed, after which it will be instructed to use the frequency control of the ammonia pump to regulate the amount of ammonia fed into the tower. 1.1.3.2. When the pressure in the synthesis tower rises to 8.0 MPa, and after a thorough inspection reveals no issues, methyl alcohol is fed in according to the requirements of the central control system. 1.1.3.3. In connection with compression, CO2 gas is fed into the synthesis tower (if the tower is started while maintaining pressure, ammonia should be fed first, followed by CO2; finally, methylamine liquid should be fed into the tower according to the requirements of the central control system). 1.2. Parking 1.2.1. Long-term parking 1.2.1.1. Upon receiving instructions from the shift supervisor or hearing the parking signal, close the valve for feeding materials into the tower; first open the CO2 vent valve to release CO2, then stop the NH3 supply, and finally stop the supply of monoethylamine. Start the flushing pump to flush into the three-material pipeline of the synthesis tower; stop the ammonia pump and switch the methyl pump to circulation mode. Once the pressure in the synthesis tower is reduced to 8.0 MPa, contact the circulation team. 1.1.1.1. Once the pressure in the synthesis tower is reduced to 8.0 MPa, ask the circulation team to discharge material from the bottom of the synthesis tower to the second stage; use the high-pressure discharge valve to control the amount of material discharged. Then, follow the instructions from the circulation team to start the flushing water pump in order to flush the outlet pipe of the synthesis tower. Turn off the leak detection steam. 1.1.1.2. When the pressure in the synthesis tower is reduced to 0.3–0.5 MPa, the flow is directed to the ammonium carbonate liquid tank for discharge. 1.1.1.3. When the pressure in the synthesis tower reaches atmospheric level, steam is used in conjunction with the circulation unit to displace the contents within the tower; once the analysis shows that the displacement is successful, the steam supply is stopped, and the top and bottom drains are opened to allow air to enter. 1.1.1.4. Stop Pump 1A and the medium and low pressure pumps as per the notification. 1.1.2. Short-term shutdown: Immediately close the shut-off valves for the three materials entering the tower, stop the supply of these three materials to the tower. Start the flushing water pump to flush the pipelines through which these materials enter the synthesis tower; simultaneously, the circulation unit should be used to flush the material pipelines. Stop the ammonia pump and use the Phase I methane pump for circulation. 1.1.3. Normal shutdown of the ammonia pump 1.1.3.1. After receiving the shutdown instruction, relieve pressure using the outlet bypass valve, close the outlet valve, and fully open the bypass valve. 1.1.3.2. Stop the main pump and the oil pump, and turn off the cooling water and seal water for the oil cooler. 1.1.4. Normal shutdown of the Type-1A pump 1.1.4.1. Set the pump to its lowest speed. 1.1.4.2. Check whether the bypass line is unobstructed. 1.1.4.3. Relieve pressure using the bypass valve, close the outlet valve; once the outlet valve is closed, fully open the bypass valve. 1.1.4.4. Stop the main pump and the oil pump, and turn off the seal water and the cooling water for the oil cooler. 1.1.4.5. After the pump has been depressurized through drainage, clean the pump and the bypass line using condensate. 1.2. Switching between the ammonia pump and the Type-1A pump 1.2.1. Inform the control room and notify the relevant personnel. 1.2.2. Start the standby pump following the normal operation procedures. 1.2.3. Perform a pressure test by using the bypass valve to bring the pressure to the same level as that of the original operating pump. 1.2.4. When reducing the amount of material fed into the tower using the original pump via a bypass line, increase the flow rate from the new pump; once the new pump has delivered all the fluid, close the outlet valve of the original pump and fully open the bypass line valve. 1.2.5. Once the new pump is operating normally, shut down the original pump. 1.3. The startup procedures for the dimethylamine pump and the ammonia water pump are basically the same as those for the methylamine pump. 2. Emergency shutdown 2.1. Reasons for emergency shutdown 2.1.1. Power outage, interruption of raw material supply, or interruption of cooling water supply. 2.1.2. Severe mechanical accidents. 2.1.3. Massive leakage of liquid ammonia. 2.1.4. Serious electrical accidents as well as fires and explosions. 2.2. Steps for emergency shutdown: Turn off the feed to the reactor and start the flushing water pump to flush the feed lines; shut down the pump and handle the inlet and outlet valves. The rest of the procedures follow those for normal shutdown. 3. Common accidents, their causes, and solutions Phenomenon Cause Solution 1. Abnormal operation of the liquid ammonia pump ⑴ Gas present in the pump without proper venting. ⑵ Faulty combination valve. ⑶ Inlet valve not open or blocked at the inlet. ⑷ Severe leakage from the pump’s bypass valve. ⑸ Severe leakage from the pump’s packing. ⑹ Safety valve fails to return to its normal position after activation. ⑺ The buffer tank is empty. ⑻ Low medium-pressure. ⑼ High temperature of the liquid ammonia. ⑴ Remove gas from the pump before starting it up. ⑵ Replace the combination valve during shutdown. ⑶ Open the inlet valve or shut down the pump for cleaning. ⑷ Seal the bypass valve; if this isn’t possible, shut down the pump and replace or repair it. ⑸ Shut down the pump and replace the packing. ⑹ Shut down the pump and re-adjust the safety valve. ⑺ Contact the control room to increase the level in the buffer tank. ⑻ Contact the control room to increase the medium pressure. ⑼ Contact the control room to lower the temperature of the liquid ammonia. 2. Abnormal operation of the methylamine pump ⑴ Faulty combination valve. ⑵ Inlet valve not open, or opened too little, or blocked at the inlet. ⑶ Severe leakage from the pump’s bypass valve. ⑷ Severe leakage from the pump’s packing. ⑸ Safety valve fails to return to its normal position after activation. ⑹ Excessively high concentration of methylamine liquid. ⑺ Unstable operation of the medium-pressure system. ⑻ Too high temperature of the methylamine liquid. ⑼ Failure of the speed control device. ⑽ Too low temperature of the methylamine liquid. ⑴ Replace the combination valve during shutdown. ⑵ Open the inlet valve wider or clean the inlet pipe. ⑶ Seal the bypass valve; if this isn’t possible, shut down the pump and replace or repair it. ⑷ Shut down the pump and replace the packing. ⑸ Shut down the pump and re-adjust the safety valve. ⑹ Contact the control room to adjust the composition of the methylamine liquid. ⑺ Contact the control room to adjust the operation of the medium-pressure system. ⑻ Stop supplying heating steam after starting the pump. ⑽ Contact the electrical and instrumentation department to address the issue with the speed control device. 3. Overpressure at the outlets of the methylamine pump and the ammonia pump ⑴ Inlet valve at the pump outlet not open, or the outlet pipe is blocked. ⑵The shut-off valve at the inlet of the synthesis tower is not open or is opened too slightly. ⑶Overpressure in the synthesis tower. ⑷Instrument malfunction (indicates overpressure, but there is no actual overpressure). ⑴Open the outlet valve or shut down the pump to handle the outlet pipe. ⑵Inlet tower valve. ⑶Contact the control room to inform them of overpressure in this position. ⑷Replace the pressure gauge. 4. Trip of the primary pump and ammonia pump ⑴ Power loss. ⑵The motor load is overloaded. ⑶Electrical malfunction. ⑷Low oil pressure triggers interlock action: (1) Inform the control room to cut power at this station and initiate an emergency shutdown. ⑵Reduce load. ⑶Notify the electrician to handle it. ⑷Remove the filter screen, top up the oil level, and increase the oil pressure. 5. Sealing water block of Pump 1A: (1) Sealing leakage in the packing of Pump 1A is severe. ⑴Stop the pump to replace the packing. ⑵ Treat the seal water pipeline. 6. Abnormal noise from the No. 1 pump gearbox. ⑴ There are foreign objects inside the gearbox. ⑵The components of the methylammonium solution are not suitable. ⑶Electrical fault ⑷ Excess oil pressure ⑸ Faulty combination valve ⑴ Stop the pump and check the gearbox. ⑵Contact the main control for adjustment. ⑶Contact an electrician to handle it. ⑷ Adjust the oil pressure. ⑸ Stop the pump and replace the combination valve. 7. Oil pump shuts down: ⑴ Low oil temperature and high viscosity. ⑵The oil has gone bad. ⑴Increase the oil temperature. ⑵Replace with new oil.