When the absolute pressure is increased from 0.55mpa to 0.6MPa, the liquefaction temperature can be increased by about 1 ℃, and the cooling capacity difference needed to condense 1kg air is about 2kJ. At this time, the bypass valve from the air to the waste nitrogen pipeline should be closed to increase the downtower pressure. Of course, there is a limit to the increase of pressure.DEAR Air separation equipment.With a large amount of oxygen condensation, the amount of argon condensation is relatively increased, and the content of argon in the gas phase is gradually reduced. In this way, an argon rich region above the liquid air inlet is formed. The distribution of argon in the upper column varies with the product and concentration of oxygen and nitrogen.Since the argon content in the air is constant, the argon content in the stripping section will decrease and the argon content in the distillation section will increase correspondingly. If the nitrogen production decreases, the nitrogen concentration will increase, and the argon rich section will move down. That is to say, the argon content in the argon rich region of the distillation section should be reduced, and the argon content in the argon rich region of the stripping section should be increased.
When a full annular gas is added, it can reduce the temperature difference at the cold end and ensure self-cleaning; the throttling effect of the air throttled by the bypass valve can recover its cooling capacity through the sewage nitrogen channel; the cooling capacity of the plate heat exchanger will move down and expand the freezing area. But it has the side effect of enlarging the temperature difference at the hot end and increasing the cooling loss.DEAR Air separation equipment.The heat transfer process of fluid passing through the wall is a complex process, and there are many factors affecting the heat transfer. The experimental results show that the hourly heat transfer Q (also known as heat load) is directly proportional to the temperature difference △ t (℃) between cold and hot fluids, and is directly proportional to the size of heat transfer area f (M2). The formula is q = 3600kf △ t (kJ / h).The amount of backflow gas and its temperature into the accumulator (or switching heat exchanger) are basically unchanged, and the heat transfer area is also unchanged, so the heat transfer temperature difference will expand. Therefore, although the temperature of the hot end of the backflow gas increases, it is less than that of the air entering the device.
DEAR Air separation equipment.When liquid began to accumulate in the main cooling system, the temperature in the nitrogen channel of the main cooling system at the top of the lower tower was higher than that of the liquid oxygen. If the temperature difference is too large and the liquid evaporates too fast, the rise of liquid oxygen level will be slow or even not. At this time, turn down the regulating valve-1 and slightly open the liquid nitrogen reflux valve, so that the distillation condition of the lower tower can be established as soon as possible.A number of interlayers are overlapped or arranged properly to form a number of parallel channels. At the two ends of the channels, the guide plates for the inlet and outlet of cold and hot fluids are equipped, and they are welded together by brazing method to form a group of plate bundles (or units). Combined with the head and pipe joint of fluid flow in and out, a complete plate fin heat exchanger is formed.DEAR Air separation equipment.When the expansion air is sent to the upper tower depends on the specific process of air separation. But the reason is the same, that is to give full play to the refrigeration capacity of the expander and reasonably distribute the cooling capacity. In some air separation processes, there is a butterfly valve at the nitrogen outlet of the upper tower, which can be turned down to increase the pressure of the upper tower.
