The automatic valve is actually a kind of one-way valve, which is installed at the cold end and central extraction of the switching heat exchanger. It is matched with the forced valve. When the positive flow air is used, the air (and intermediate air extraction) automatic valve will open and the sewage nitrogen (or oxygen, nitrogen) automatic valve will close; when the backflow air is used, the sewage nitrogen automatic valve will open and the air automatic valve will close.When the boiling point difference between rare gases is very large, the components with high boiling point can be condensed and frozen out. When separating neon and helium, because neon is frozen at 24.3k and the liquefying temperature of helium is 4.178k, liquid hydrogen can be used as the cold source to separate neon and helium.DEAR Cryogenic air separation unit.This kind of regulation method is only effective when the on-6 valve is closed very small (within one revolution) and the high pressure air pressure is not equal to the pressure in front of the expander. And each adjustment can only rotate 3-5 degrees, not too large.
DEAR Cryogenic air separation unit.The generation and accumulation of liquid in the main cooling tower depend on the liquid hollow section of the lower tower to flow into the upper tower. When liquid air appears in the lower tower and throttles to the upper tower, part of the liquid vaporizes after throttling, and the temperature further decreases. These low-temperature liquids and gases are used to cool the upper tower.Heating stage: the inlet temperature of sewage nitrogen increases rapidly, but the outlet temperature will continue to decline at the beginning, and then gradually increases. Because the heat at this time is first consumed in the heat required for desorption, the middle and upper molecular sieves of the bed are desorbed, and the heat is stored in the bed. The influencing factors of regeneration effect in this stage are nitrogen flow rate, heating time and regeneration temperature. The main purpose is to monitor the inlet temperature of sewage nitrogen.Since the subcooler and liquefier can fully recover the cooling capacity of the expansion air, it is unnecessary to send air to the upper tower too early. When the main cooling liquid area is enough, the normal distillation condition is established, it is appropriate to stop one expander and then send gas to the upper tower.
Membrane air separation method: it uses the permeation selectivity of some organic polymer membranes. When air passes through the membrane (0.1 μ m) or hollow fiber membrane, the speed of oxygen passing through the membrane is about 4-5 times that of nitrogen, so as to realize the separation of oxygen and nitrogen. The oxygen enrichment concentration of this method is generally suitable for 28% - 35%, and the scale is only suitable for medium and small scale.The unit of entropy is J / (mol · K) or kJ / (KMOL · K). However, what we usually care about is not the value of entropy, but the change trend of entropy. For the actual adiabatic expansion process, the entropy must increase. The smaller the increase of entropy, the smaller the loss and the higher the efficiency.The argon fraction enters from the bottom, and the liquid at the bottom contains high argon, which returns to the main column for distillation. Therefore, only a part of argon in argon fraction is extracted as crude argon product, and the amount of argon fraction required is about 35-40 times of that of crude argon.
