Use of nitrogen in the ammonia synthesis process

It is mainly used for replacement during startup and shutdown, as well as for dry-pressure charging protection of standby and inactive equipment. For example: shutdown for maintenance and purging of boiler burners and fuel gas pipelines, N2 purging before restarting the burners, purging of process pipelines, and dry protection when the boiler is out of service. There are also very few cases where the nitrogen-filled bladders in the turbine oil system are used as sealing gas for dry gas seals, etc.

1. Nitrogen protection and nitrogen purging for plant shutdown. 2. Stamping and nitrogen heating during the driving process. 3. In daily production, some tanks are filled with nitrogen to remove air from the tanks. Partially sealed air source.

One of the raw materials for ammonia synthesis is medium-pressure high-purity nitrogen (99.8% purity)； Used for replacement during startup and shutdown, as well as for dry pressurization protection of standby and decommissioned equipment, and for the dry gas seal air of compressors (mainly low-pressure nitrogen).

Thank you all for your answers. I was wondering: is the amount of nitrogen used generally large? Are the devices based on cryogenic methods or PSA technology? I’m thinking that if oxygen isn’t needed in the production process, then a PSA nitrogen generation system should suffice, right?

1. Nitrogen protection and nitrogen purging for plant shutdown. 2. Stamping and nitrogen heating during the driving process. 3. In daily production, some tanks are filled with nitrogen to remove air from the tanks. Partially sealed air source. 4. For the conversion of coke oven gas, oxygen + nitrogen can be used as a substitute for oxygen-enriched air; our plant uses cryogenic air separation

May I ask what is the annual production capacity of ammonia synthesis at your facility, in terms of tons? What is the capacity of the deep cryogenic air separation unit in use there? What is your demand for nitrogen in standard cubic feet per hour? Thank you! I would like to compare whether it is more cost-effective to use a deep cryogenic system or a PSA system at that scale

1. Purging during testing 2. Passivation of the catalyst in the synthesis tower 3. Regeneration of silica gel

Used for replacement during startup and shutdown, as well as dry pressurization protection for standby and decommissioned equipment. For example: switching to methanol, ammonia, or catalyst protection gas during major repairs. Shutdown for maintenance and purging of boiler burners and fuel gas pipelines; N2 purging before restarting the burners; purging of process pipelines; purging for hot work on maintenance pipelines and towers; dry protection when the boiler is out of service, etc. There are also very few cases where they are used as nitrogen-filled bladders in turbine oil system accumulators, as sealing gas for dry gas seals, or as supplementary gas for the nitrogen-filled bladders in oil pressure system accumulators.

1. In the ammonia synthesis process, nitrogen is an important feed gas, which is mixed with hydrogen from the gas generation and purification section in a ratio of 1:3. 2. In the carbon dioxide stripping towers of some gas generation processes, the purifying gas is nitrogen. 3. Before starting the gasifier, the oxygen pipeline must be purged with nitrogen. 4. Used for pressure testing and leak detection of relevant pipelines in the synthesis workshop. To ensure the safe use of catalysts in all stages, the purity of nitrogen should be above 99.9%. This post was last edited by Nine Heavens is me on 2009-2-21 09:46.]

1: The nitrogen used in Workshop 2 for synthesis (including N5 and N120) is supplied by Workshop 1 for synthesis. To ensure that Workshop 1 is not affected during use and to maintain safety, these regulations have been established.
2: N5 System
1. There are several public connection points for N5 in Workshop 2, as follows:
(1) Next to 121-C
(2) South of 114-F
(3) On the fourth-floor platform of 105-D
(4) Next to 108-C
(5) North of 127-C
(6) South of 102-E
(7) 105-J
(8) 104-D
(9) 103-D
Under normal conditions, the valves at these nine public connection points are fully closed. If nitrogen needs to be drawn from these points for nitrogen purging of equipment and pipelines, the following procedures must be followed:
(1) Confirm that the pressure inside the equipment and pipelines to be purged has been reduced to atmospheric pressure.
(2) Contact the dispatch team to confirm that the N5 system can be used.
(3) Take samples from the N5 connection points for analysis; the oxygen level must be zero

To understand the use of nitrogen, it is necessary to be aware of what kind of gasification process, as well as what kind of shift and decarburization processes are used. In the case of ordinary hydrocarbon conversion, only a small amount of nitrogen is used in the system as an auxiliary. In the case of oxygen-enriched gasification, it is necessary to adjust the hydrogen-to-nitrogen ratio in the syngas; whereas in Shell gasification, large amounts of nitrogen are required for coal feeding, burner protection, backwashing, and adjusting the hydrogen-to-nitrogen ratio. In decarburization as well, a large amount of nitrogen is often used as the stripping gas. The above are those commonly and extensively used in ammonia synthesis. As for system leak testing, pressure testing, pressure holding, purging, and emergency backup, the amounts used in these processes are very small, and they are not used frequently. Is it really necessary to have a dedicated air separation unit for this purpose? Our plant has 28,000 units for air separation and cryogenic processing, as well as 46,000 units for nitrogen production (covering high, medium, and low pressure levels), but this is not sufficient.

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