In normal production, the air pressure (e.g. 2.0MPa) is lower than the critical pressure, the corresponding saturated steam temperature is 119k (- 154 ℃), and the specific enthalpy is 1760j / mol. When the temperature of air in the main heat exchanger drops to the above temperature, some air will be liquefied, and the lower part of the heat exchanger acts as a liquefier. After throttling, the liquid containing air is still in the saturated zone and maintains a certain liquefaction rate. After mixing with the expanded air, it enters the lower tower in a moist state. As the temperature of the positive flow air into the main heat exchanger also increases, the maximum reheating temperature of the low-temperature and low-pressure gas in the backflow can be equal to the inlet air temperature T ′ 2, that is, t ′ 4 = t ′ 2. Accordingly, the enthalpy is h ′ 4.
The process argon obtained from the crude argon after deoxidization and drying needs to further remove the nitrogen and excess hydrogen in order to obtain the refined argon (containing more than 99.99% argon). Generally, distillation is used to remove nitrogen and hydrogen in refined argon column. The process argon is cooled in the heat exchanger and throttled into the middle of the refined argon tower. Argon is a nonvolatile component relative to nitrogen. Therefore, the argon content in the downstream is constantly increasing, and high purity liquid argon can be obtained at the bottom of the tower. The operation condition of refined argon tower of air separation plant manufacturer mainly depends on whether the condenser and evaporator work well together. If the cooling capacity of the condenser is too much, the condensation capacity is too large, and the reflux liquid is too much, the nitrogen part will not evaporate sufficiently, and the argon at the bottom may be polluted by nitrogen, thus reducing the purity of argon.
Equipment resistance of air separation plant manufacturers increased. Due to the blockage of tray, liquid air adsorber or subcooler, the opening of liquid air and liquid nitrogen throttle valve is too small or blocked, the pressure of lower tower will rise and the air flow into tower will decrease. When the switching heat exchanger freezes, the resistance of the system will increase and the air flow into the tower will automatically decrease. In order to ensure continuous gas supply, air separation plant manufacturers need to use more than two adsorption towers alternately. The method of regeneration can be heating to increase temperature (TSA) or reducing pressure (PSA). This method has the advantages of simple process, convenient operation and low operation cost, but it is difficult to obtain high purity product, and the oxygen purity of the product is about 93%. Moreover, it is only suitable for separation units with small capacity (less than 4000 m3 / h).
The plate fin heat exchanger of air separation plant manufacturer has great adaptability, which can be used for heat exchange between different fluids of gas gas, gas-liquid and liquid-liquid. Moreover, through the arrangement and combination of various flow channels, it can adapt to different heat exchange conditions such as counter flow, cross flow, multi stream flow and multi pass flow. The main fault in the valve body is that the sealing surface between the valve top and the valve seat is not tight, which causes the valve not to close. The most common is the O-ring rubber seal off. This is mainly related to the uncleanness of the bonding surface and the poor quality of the adhesive. In addition, there are foreign matters at the valve seat; The concave convex spherical washers at both ends of the valve stem and valve top are screwed too tightly or too loose; The fixed nut is not tightened, which causes the valve top to be loose; The bending of the valve stem may cause the valve to close loosely.
For the same heat transfer area, the number of long tubes is less than that of short tubes, so the diameter of condensing evaporator can be reduced. Moreover, because it is in tube evaporation, bubbles are constantly generated in the evaporation process, and the flow disturbance is intense. The heat transfer coefficient is about 800 w / (M2 ·℃), and the consumption of metal materials can be reduced. For the liquid oxygen pump, the liquid oxygen at its inlet should be in the supercooled state, because if part of the liquid oxygen is gasified in the pump, the capacity of the pump will be reduced, and the liquid oxygen can not be smoothly transported to the main cooler. When the pressure of the upper tower drops too much, the temperature of the liquid oxygen at the inlet of the liquid oxygen pump will exceed the saturation temperature corresponding to the pressure, resulting in the gasification of part of the liquid oxygen and the "entrainment" phenomenon, so that the liquid oxygen can not be sent out, resulting in the rise of the liquid level at the bottom of the upper tower.
