In addition, helium is the best refrigerant for cryocooler. Helium liquefier and helium refrigerator can obtain low temperature close to absolute zero. The pump operated by liquid helium can reach 133.32 × 10-9pa high vacuum in electronic industry and 133.32 × 10-10 ～ 133.32 × 10-12pa ultra vacuum in space research.At the beginning, the amount of air that can be fed into the air separation tower is very small, because the liquid air, liquid nitrogen pipeline and control valve are considered according to the flow rate of liquid, and the specific volume of gas is much larger than that of liquid, so the ability to pass through gas is limited. With the accumulation of liquid, when there is liquid in the main cooling, the condensing evaporator will start to work, and part of the rising steam in the lower tower will condense into liquid in the main cooling.Due to the hard work of valve opening and closing, the valve stem is often twisted and the hand wheel is broken. Therefore, after the maintenance of the valve, the packing should be installed evenly and tightly, and the compression nut should be tightened. During the overall leakage test of air separation unit, the leakage at the valve rod packing should also be checked, and this problem should be solved before cold start-up.
Entropy, like temperature, pressure and enthalpy, is also a physical quantity reflecting the internal state of matter. It can't be measured directly with instruments, it can only be calculated, so it's more abstract. Sometimes it is convenient to use the concept of entropy in theoretical analysis.DEAR Cryogenic air separation unit.The content of argon in the gas phase should be gradually reduced, but because the content of oxygen in the gas phase is greater than that of argon, and oxygen is a difficult volatile component for argon, oxygen condenses more into the liquid phase than argon, so the concentration of argon at the first few trays is relatively higher.DEAR Cryogenic air separation unit.Shorten the adsorption cycle to ensure the work within the allowable range of adsorption capacity; pay attention to monitor the carbon dioxide content in the air at the outlet of the adsorber below 1 × 10-6. At the same time, reduce the product nitrogen flow properly, increase the nitrogen flow of decontamination nitrogen cooling tower to reduce the temperature of cooling water as much as possible, and increase the flow of common cooling water.
DEAR Cryogenic air separation unit.If the effective energy of the environmental state is zero, the air is separated into oxygen and nitrogen, that is, in an unbalanced state with the environment, it needs to consume energy, that is, the separated product has effective energy. Because the raw air is in the environmental state, its effective energy is zero.If you want to increase the output of liquid products and open one more expander in normal production, it is OK only from the perspective of cold balance, but too much expansion air into the upper tower will destroy the distillation condition of the upper tower and reduce the extraction rate of low oxygen. At the same time, taking more liquid will also affect the working condition of the heat exchanger in the tower and the reflux ratio of the distillation tower, so it is also limited.Large size gate valves and pneumatic control valves should be installed vertically to avoid deviation due to the heavy weight of the valve core, which will increase the mechanical wear between the valve core and the bushing and cause leakage; when tightening the compression screw, the valve should be slightly open to avoid damaging the top sealing surface of the valve.
