Cooling principle of the small ice mechanism in the vent gas from ammonia tanks at low temperature and normal pressure

Gaseous ammonia condenses into liquid ammonia; a certain pressure corresponds to a certain temperature: that is, as long as the pressure remains relatively stable, cooling it to the corresponding temperature will result in the formation of liquid ammonia； Or, if the temperature remains relatively stable and pressure is increased to the corresponding value, it becomes liquid ammonia. An ice machine utilizes this principle to compress gaseous ammonia into liquid ammonia.

How can I keep the temperature during the compression process relatively stable?

As the pressure increases, the boiling point of ammonia rises, and liquid ammonia is thus formed. At 1.5 MPa, ammonia at 30 degrees remains in liquid form. Large and small refrigeration units both operate on this principle; if you pay attention, you will see that large refrigeration units are equipped with three flash tanks whose pressure gradually decreases, and the ammonia gas produced in these tanks – at high, medium, and low pressures – enters respectively the high-pressure and low-pressure sections of the ammonia compressor. The liquid ammonia from the high-pressure flash tank is sent to some ammonia cooler users, while the rest is pumped to an ammonia tank for storage. Each ammonia cooler undergoes heat exchange to turn into ammonia gas, which then returns to the flash tank where it flashes back into ammonia gas before being sent to the high-pressure cylinder of the ammonia compressor.

This question is a bit hard to understand. The temperature of ammonia in a tank at low temperature and normal pressure is usually -33°C, with practically no non-condensable gases dissolved in the liquid ammonia. The off-gas mentioned by the original poster is likely the ammonia vapor that results from flashing The cooling principle is the same for both small and large ice machines. As explained on the second floor, a small ice machine increases the pressure by pumping in ammonia, thereby raising the condensation temperature of gaseous ammonia; this allows the gaseous ammonia to be cooled using ordinary circulating water and turned into liquid ammonia. At high water temperatures, a higher pressure is required; at lower water temperatures, the temperature can be kept lower. Of course, it is also possible to condense gaseous ammonia at very low pressure using a very cold liquid; however, the cooling energy required for such a cold liquid must also be provided by some other substance. This post was last edited by huangwf98 on 2008-2-28 11:10.]

Following the same cooling principle, the condensed liquid ammonia is returned to the low-temperature storage tank via throttling

The refrigeration principle generally involves four processes: 1. Evaporation, 2. Compression, 3. Condensation, and 4. Throttling. When the large tank absorbs heat from the surroundings, the ammonia inside it evaporates; it is then compressed by a large or small compressor, and after condensation and throttling through a throttle valve, it turns back into liquid ammonia. There is inevitably some non-condensable gas in the gaseous ammonia, and if the exhaust pressure of the compressor is high, this pressure can be reduced by releasing the non-condensable gas. Otherwise, the compression work required by the compressor increases, leading to higher energy consumption, which is also detrimental to the machine itself. Fellow colleagues upstairs, I wonder if your large compressors are driven by steam? Especially the guy on the sixth floor – I really want to communicate with you. The processes in my factory seem to be similar to what you described, and I look forward to exchanging ideas with you