Purging steps for the initial startup of the ammonia synthesis unit

Purging of the ammonia synthesis system ①Preparations before purging: A. The ammonia absorbers, copper washers, various ammonia coolers in the synthesis unit, as well as all gaseous ammonia pipelines, are purged simultaneously with this system. B. Remove the relevant flanges of each device and main valve in sequence according to the process, and insert the baffle. C. Open the vent valves, drain valves, oil discharge valves, and drain valves of each device, and remove the gas and liquid phase valves of the pressure gauge valves and level gauges. ②Purging operation: Start the chiller following the normal operating procedures; air is drawn in through the inlet, and the pressure is increased to 0.2–0.3 MPa. Purge each piece of equipment and each section of pipeline sequentially (it is not allowed to bypass connections between equipment, pipelines, valves, or different sections of the system). Blowing out of the vent, drain, and instrument pipelines is carried out simultaneously. When cleaning, gently tap the outer wall with a wooden hammer to adjust the flow rate, making it larger or smaller, and repeat this process several times until the gas emitted is clean and meets the standards. During the purging process, after each section is purged, the relevant baffle is removed immediately, and the corresponding valves and flanges are installed.

Synthesis system cleaning and purging plan. Purpose of purging: During installation, residues such as welding slag, iron filings, and dust may remain in the equipment and pipelines. If these are not removed, they can block the equipment, pipelines, and valves once operations begin, affecting production and safety. Therefore, it is necessary to clear these debris before driving to ensure smooth driving and prevent accidents. I. Preparatory work before purging 1. Before purging, it is necessary to check that all equipment pipelines, flanges, valves, instruments (a gauge with a low range should be used for the purging pressure gauge), safety devices, etc. are present in full, and that the flow path is unobstructed, to ensure compliance with production safety and process requirements. 2. Prepare a blind flange (determined according to the size of the pipe opening), a wooden hammer, tin, white cloth, or white paint to check whether cleaning is thorough. 3. Before cleaning, each department’s personnel must have clear responsibilities, and the cleaning process can only proceed with the approval of the chief commander and deputy chief commander. 3. Blowing must be completed thoroughly; work can only stop after the test run team gives approval. Blowing clean requirements: 1. Overall blowing clean requirements dictate that rust, slag, and other debris must not be allowed to enter the equipment, in order to prevent blockages in various drainage outlets. Remove the inlet flanges or short pipes of each device and install blind plates. 2. Detailed records must be kept for cleaning each device and every pipe section. 3. Compressed air is used as the medium for cleaning at this stage. 4. During the cleaning process, it is necessary to protect the contact surfaces of the inlet flanges of various equipment to ensure that the sealing surfaces are not damaged. 5. During the purging process, the flange in front of the valve must be removed; purging should be carried out first, and then the valve should be opened to purge the subsequent section. 8. In the process of purging, it is necessary to stop purging in case of special circumstances or when safety is at risk. 9. Drying time: All installation work is completed. 8. Purging pressure: During the air purging process of the system, it is necessary to keep the system pressure at no more than 2.0 Mpa, and ensure that the pressure difference inside and outside the synthesis tower, heat exchangers, and cooling exchangers is no more than 0.8 Mpa, in order to prevent leakage from occurring in the equipment. III. Purging step (using the main valve for make-up air to control the air flow for purging the equipment and pipelines behind the tower): 1. Remove the flange in front of the make-up air inlet valve, and purge the pipeline ahead of the inlet valve; once purging is complete. Remove the flange at the inlet of the ammonia cooling system for supplementary gas supply, install a baffle, and blow the supplementary gas into the flange at the inlet of the ammonia cooler. 2. Remove the flange on the outlet pipe of the ammonia cooler, and blow out the ammonia cooler through the inlet pipe. 3. Remove the oil inlet flange from the outlet flange of the diammonia cooler. Blow clean the oil inlet pipeline. 4. Connect the oil separator inlet flange, remove the oil separator outlet flange, and open the oil separator drain to blow it clean. 5. Connect the oil outlet flange; add a blind plate below the ammonia cooling inlet tee, remove the ammonia cooler inlet flange and the cold exchanger outlet flange, and blow out the ammonia cooler inlet pipeline. 6. Connect the inlet flange of the ammonia cooler; remove the outlet flange of the ammonia cooler and install a blind plate at the outlet of the heat exchanger. First, purge the ammonia-cooled ammonia fraction. 7. Remove the ammonia cooling outlet flange and purge the ammonia cooling system; once this is done, reattach the ammonia cooling outlet flange. Then remove the ammonia separation inlet flange and purge the pipeline from the ammonia cooling outlet to the ammonia separation inlet. After that, reattach the ammonia separation inlet flange and remove the ammonia separation outlet flange, opening the ammonia outlet to purge the ammonia separation system. After completion, connect the ammonia outlet, remove the flange at the cold exchanger inlet, and purge the pipeline leading from the ammonia to the cold exchanger inlet. 8. Remove the flange at the cold junction outlet and add a baffle. Blow out the cold exchanger; once that is done, connect the flange at the outlet of the cold exchanger, remove the blind flanges at both ends of the inlet of the circulation pumps, and remove the flanges in front of the inlet valves of the four circulation pumps. Then blow out the section from the cold exchanger to the main inlet pipe of the circulation pumps. 9. Once completed, connect the flanges and install blind flanges at both ends. Remove the inlet flanges of the four circulators and blow out the inlet branches of the circulators. 10. Close the inlet valve of the circulation machine. Connect the flange at the inlet of the circulation machine, remove the flange in front of the outlet valve, and blow air through the pipeline leading to the outlet valve using the circulation machine. Connection flange. Unscrew the inlet flange of the oil at the outlet of the circulation pump. Blow clean the outlet of the circulator to the oil distribution line. 11. After completion, connect the flange and remove the oil outlet flange. Blow off the oil residue. After completion, connect the flange, and remove the flanges in front of the main valve and the branch valve. Blow out the pipeline between the two valves to remove oil, then connect the flanges and open the main valve. Remove the pipeline flange at the entrance of the synthesis tower. Blow out the area between the main tower valve and the synthesis tower. Close the main tower valve once it is done. 12. Remove the flange in front of the F3 feed line valve, the flange at the outlet of the synthesis tower, and the flange for the hot gas inlet; blow clean the outlet pipeline, and then install a blind plate at the outlet of the synthesis tower. Remove the flange from F3 to the top of the synthesis tower, open F3, and purge its branch lines; once this is done. Remove the flange at the hot air outlet of the heat exchanger and blow out the heat exchanger. Once finished, connect the flange. 13. Open the flange before the feed line valve, remove the inlet flange of the synthesis tower; after cleaning it thoroughly, install a blind plate at the inlet. Then remove the inlet flange of the synthesis tower’s feed line and clean that feed line as well. 14. Once completed, remove the flanges before the valves in the F1 and F2 bypass systems, and blow out the pipelines ahead of those valves. Once completed, remove the flanges of F1 and F2 up to the top of the synthesis tower, open the branch line valves of F1 and F2, and purge their branch line pipes. 15. After completion, a blind plate is installed at the inlet of the ammonia cooler; the inlet flange of the heat exchanger is removed, and the heat exchanger is purged. Once finished, connect the flange. 16. Remove the flange of the water-cooling outlet valve, blow out the area from the water cooler to the heat exchanger, and then reattach the flange. Remove the heat exchanger outlet flange and blow out the area from the heat exchanger outlet to the water-cooling pipeline. After that, connect the flange. 17. Remove the heat exchanger inlet flange and blow out the heat exchanger. Once completed, connect the heat exchanger inlet flange. Remove the waste heat boiler outlet flange and blow out the section from the waste heat boiler outlet to the heat exchange pipeline. After that, connect the flange. 18. Remove the inlet flange of the waste boiler and blow it clean. Once finished, connect the flange. 19. Disconnect the second outlet flange of the synthesis tower and purge the pipeline leading to the secondary waste boiler.