Ammonia synthesis, high-pressure ammonia separator, medium-pressure ammonia separator, temperature setting
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In the ammonia synthesis process, the ammonia splitter functions similarly to a flash separation process. The outlet at the bottom of the high-pressure ammonia separator is at -7°C and 13.2 MPa; the fluid from this bottom outlet enters the medium-pressure ammonia separator, whose outlet at the top is at -4.7°C and 2.9 MPa. Why does the temperature rise after pressure is reduced?
The result obtained using the PR method is a temperature rise to -4.4°C. The reason for this phenomenon is not the expansion of hydrogen gas, which would cause a temperature increase; the small amount of gas dissolved does not suffice to lead to an overall rise in temperature. Moreover, the evaporation of ammonia occurs when the gas is released, and this process absorbs heat. The actual cause is the work done by the high-pressure liquid, which possesses a large amount of potential energy; once it passes through the pressure relief valve, this energy is converted into heat