DEAR Air separation plant.When the packing is not uniform or tight, or the valve stem is not straight or round, the cryogenic liquid or gas will leak out along the gap of the packing. As the cooling capacity is transmitted, the moisture in the air will freeze on the packing and freeze the valve stem. In this case, only steam or hot water can be used to heat the packing to open and close the valve. However, after the valve is opened and closed, the water accumulated in the packing will freeze again.The adjustment of the temperature condition of the accumulator (or switching heat exchanger) is based on the middle temperature. The "middle part" here does not refer to the median position in geometric dimension, but refers to the temperature on the cylinder (or switching channel) near the outlet of the middle suction or circulation.First, increase the circulating current to keep the front of the machine at a higher temperature (e.g. - 120 ℃), so that the carbon dioxide content in front of the machine is in an unsaturated state. After expansion, carbon dioxide is not easy to precipitate in the machine. When the temperature of the cold end reaches - 150 ℃, the amount of carbon dioxide brought into the expander is very small, so the bypass and circulation can be cut off temporarily, so that the temperature in front of the expander can be reduced rapidly, and the expander will not be blocked if it is forced to cross the carbon dioxide freezing zone in about 10 minutes.
The long tube condensing evaporator is evaporation inside the tube and condensation outside the tube. Its boiling intensity and condensation intensity are related to the geometric size of the tube. The experimental results show that when the unit heat load Q (heat transfer per unit area and time) is constant, the larger the ratio L / Di of tube length L to tube inner diameter Di, the stronger the boiling heat release.When the amount of backflow gas increases and the amount of positive flow air and its inlet temperature remain unchanged, the situation is opposite to the above. That is to say, the middle temperature decreases, the cold end temperature decreases, the cold end temperature difference decreases, and the hot end temperature difference expands. The range of temperature change in the middle is also larger than that in the end. To sum up, the change of middle temperature can reflect the change of cold end and hot end temperature condition, and the change is significant and easy to detect.
The disadvantage of the long tube type is that it can not be directly installed between the upper and lower towers, and the piping is more complicated. The length of short tube is about 1.5m, which is evaporation outside the tube and condensation inside the tube, and the heat transfer coefficient is small. Its advantages are that it can be directly installed between the upper and lower towers, with simple structure and compact layout. Generally used in small air separation plant.If the nitrogen content of the argon fraction is too much, the purity of the crude argon will be reduced, and the temperature difference of the crude argon condenser will be reduced, or even zero, and the crude argon tower will stop working. Moreover, too much nitrogen in the crude argon will bring difficulties to the production of refined argon, so the argon fraction should be located in the place with as little nitrogen as possible.DEAR Air separation plant.After grouting for 7 days, tighten the screws and recheck the verticality of the tower again. Then, the pad iron and the bottom plate shall be welded firmly, and the slurry shall be sealed around; the connecting pipeline shall be installed, and the air tightness of the connecting pipe flange and welded joint shall be inspected. Generally, it is qualified if there is no bubble in soapy water.
