For air separation in ammonia synthesis plants, it is more cost-effective to use separate refrigeration or ammonia compressors for cooling
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Due to the ammonia compressor, about 4 tons of ammonia per hour are used for air separation cooling. Using larger units offers greater advantages due to higher efficiency and more stable operation, and it also allows for the reduction of one smaller chiller. However, the figures I calculated show that the use of an ammonia compressor increases the steam consumption in the turbine, resulting in higher operating costs. I don’t know why; who has calculated it?
That’s impossible! I haven’t done specific calculations, but it’s definitely more cost-effective to use an ammonia compression system for cooling. Approximately 4 tons of ammonia are required per hour for air separation cooling, and this doesn’t result in much increased steam consumption with an ammonia compression cooling system. If a separate cooling unit is used, an additional chiller would be needed; moreover, many organizations prefer to use imported equipment, which incurs high maintenance costs and requires motors with high power output. It is estimated that the original poster overestimated the amount of steam required for compression refrigeration (the pressure at the inlet of the ammonia compressor is negative, while the pressure of the gas exiting the ammonia cooler in the air separation unit is relatively high; it’s not clear how to estimate the steam consumption required for cooling in the air separation unit separately), which led to overly high values in the calculations.
Why not change the process to use the previous water-cooled tower, and then utilize the excess polluted nitrogen and nitrogen gas for heat exchange? Wouldn’t that be more cost-effective! :lol
A well-designed air separation unit shouldn’t require external cooling, right?