Operating procedures for commissioning of ammonium sulfate saturator

1. Normal operation: (1) The saturator uses a continuous acid addition system; the acidity of the circulating mother liquor is analyzed every half hour, with the acidity level to be maintained between 3-5%. (2) Adjust the temperature of the gas after the gas preheater in a timely manner according to the temperature of the mother liquor. (3) The circulating mother liquor pump must operate continuously; if it fails, operations shall be halted and a backup saturator shall be prepared for use. (4) The full-flow outlet of the saturator must flow at full capacity. (5) During normal production, the acid tar in the full-flow trough is regularly removed at the end of each shift. When preparing the mother liquor, remove the acid tar from the mother liquor tank in a timely manner. (6) The secondary spraying pump must spray continuously; if a fault occurs, the pump must be stopped for inspection, and feeding under elevated temperature is prohibited after the pump is stopped. (7) The crystallization pump should operate continuously; the centrifuge is started to extract ammonium sulfate crystals when the crystal content in the mother liquor reaches 30%, and the centrifuge is stopped when this content drops to 5%. (8) Add acid and carry out the mother liquor preparation. The saturator undergoes acid addition every 24 hours, with the acidity level maintained at 8-10%. After acid addition, the mother liquor is circulated for 30 minutes, after which the process of preparing the mother liquor continues, ensuring that the acidity remains above 4%. 2. Commencement of operation (1) Before starting up, check whether the internal and external auxiliary equipment are ready for operation, and open the vent valve on the gas pipeline at the saturator outlet. (2) Start the secondary spraying pump to add liquid to the saturator or pour water into it until the water level in the saturator’s flow trough is at full capacity. (3) Remove the blind flanges from the gas inlet and outlet valves, slightly open the gas inlet valve, and use a gas expeller to remove the air from inside until the explosion test is successful. (4) Start the mother liquor circulation pump for spraying, and add acid to control the acidity at 4%. (5) Shut off the gas pipeline vent; first open the gas outlet valve of the saturator, then gradually increase the opening of the saturator inlet valve. (6) Start ammonia vaporization; the ammonia gas enters the saturator. (7) In the event of any abnormality during operation, it should be stopped; the cause should be identified and corrective actions taken before resuming operation. (8) Once normal operation is resumed, shut down the other saturator and close its gas inlet and outlet valves; open the vent valve. 3. Shutdown (1) When a saturator is shut down or undergoing routine maintenance, it must be done while another saturator is operating properly. (2) When crystallization extraction in the saturator is complete (crystal ratio less than 5%), acid is added to the vessel, with the acidity controlled at 8-10%. (3) After closing the inlet and outlet valves of the saturator gas, start the circulation pump for the discharge mother liquor, the crystallization pump, and the secondary spraying pump. (4) Use a steam cleaner to purge the gas inside until steam is emitted from the outlet, then stop the steam supply after 10 minutes. (5) Drain the mother liquor from the saturator, open the lower manhole, clean it thoroughly, and then have the mechanical maintenance team conduct an inspection. Start-up and shutdown procedures for the mother liquor circulation pump, crystallization pump, and secondary spraying pump: 1. Starting the mother liquor circulation pump: (1) Open the cooling water valve of the mother liquor circulation pump. (2) Check the lubricating oil level of the pump; it should be at the center of the oil sight glass. (3) Turn the coupling 1 to 2 revolutions. (4) Open the inlet valve of the mother liquor circulation pump to expel all air from within the pump. (5) Start the motor, and check whether the current and pressure are within the specified values. The pressure in the distribution box should be 0.15–0.22 Mpa, and the current must not exceed the rated value. 2. Turn on the crystallization pump: (1) Open the cooling water valve of the pump. (2) Check the lubricating oil level of the pump; it should be at the center of the oil sight glass. (3) Turn the coupling 1 to 2 revolutions. (4) Open the inlet valve of the pump to expel all air from inside the pump, then close the outlet valve. (5) Start the motor and adjust the outlet valve (be careful not to overload the current). 3. Turn on the secondary spraying pump (same as above). 4. Pump shutdown procedure: (1) Close the pump’s outlet valve. (2) Turn off the power supply. (3) Turn off the cooling water after the pump stops rotating. (4) Close the inlet valve. V. Technical specifications: 1. Acidity of the mother liquor in the crystallization chamber: 3-5%. 2. Acidity of the mother liquor in the crystallization chamber with additional acid added: 8-10%. 3. Mother liquor temperature: 50-60°C. 4. Ammonia content after the saturator: ≤50 mg/m3. 5. Resistance of the saturator: ≤3000 Pa. 6. Specific gravity of the mother liquor: (1.26-1.32 g/cm3). 7. Saturator cleaning: It should be cleaned by adding acid every 24 hours, and the mother liquor should be filled up to the tank’s capacity. 8. Temperature of gas after preheater: 60-700°C

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