DEAR Air separation equipment.The inlet and outlet temperature of the expander will drop very low, the refrigeration capacity will be reduced, and the operation is not safe. At the same time, the liquid level will also be in the "hovering" situation. At this time, the expansion should be reduced, and the role of subcooler and liquefier should be brought into full play. Some units lead the expanded air into the upper tower ahead of time, which increases the temperature of the backflow gas at the cold end of the accumulator and changes the subcooling conditionThe oxygen concentration is between 35% and 90%. For the flash furnace with an annual output of 3600t / a copper, an oxygen generator with a production capacity of 3000m3 / h and oxygen purity of 95% is needed. For a smelter with a capacity of 1 000 t / a of lead and zinc, an oxygen generator with a capacity of 1 500 m3 / h and oxygen purity of 95% is needed. Because it requires low oxygen purity, relatively speaking, the required capacity of oxygen generator is small, so molecular sieve adsorption oxygen generator can be used.
DEAR Air separation equipment.In the main condensing evaporator, with the continuous evaporation of liquid oxygen, acetylene and other hydrocarbons contained in it will be continuously concentrated. For the sake of safety, it must be removed. Setting auxiliary condensing evaporator is one of the cleaning methods.The chemical property of nitrogen is not active, it has great inertia in the normal state, and it is not easy to react with other substances. Therefore, nitrogen is widely used as protective gas in metallurgical industry, electronic industry and chemical industry. For example, protective gas for cold rolling, galvanizing, chromium plating, heat treatment and continuous casting; sealing gas for blast furnace top and converter hood to prevent combustible gas leakage, and cooling gas for coke in CDQ device. The nitrogen purity required by general protective gas is 99.99%, and some require that the nitrogen purity is above 99.999%.DEAR Air separation equipment.The air separation unit with switching purification process refers to the self removal of water and carbon dioxide in the channel of switching plate fin heat exchanger (or cold accumulator) by switching the switching valve. In the air separation unit with switching purification process, circulation or intermediate extraction is often used to reduce the temperature difference at the cold end of plate fin heat exchanger (or cold accumulator);
DEAR Air separation equipment.The cooling of each equipment is carried out in stages, so the cooling is uniform and the thermal stress is small. In addition, in the second cooling stage, the cooling capacity of each equipment in the cooling tower is large, which makes the expander run for a long time at a higher inlet temperature, so as to give play to the large cooling capacity of the turbo expander at high temperature and shorten the start-up time.DEAR Air separation equipment.Due to the contact heat transfer, part of the water evaporates into the waste nitrogen. Due to the absorption of the latent heat of evaporation, the temperature of the effluent may be several degrees lower than that of the incoming sewage nitrogen. The temperature difference is related to the cooling water quantity, inlet water temperature and the amount of water allowed to evaporate in the polluted nitrogen. When the water quantity is constant, the higher the outlet temperature of sewage nitrogen is, the more sensible heat it absorbs and the corresponding saturated water content.
DEAR Air separation equipment.The difference of air inlet and outlet temperature is related to the air inlet temperature. Because the higher the temperature of the air inlet is, the greater the saturated moisture content is, the higher the removal load of the adsorber is, the greater the adsorption heat is, and the temperature difference will increase accordingly. When the air inlet temperature is 10 ℃, the temperature rise is about 4 ℃.From the vaporization temperature (saturation temperature) of liquid oxygen, if the liquid oxygen surface is too high, the greater the static pressure difference between the upper and lower liquid oxygen surface, the higher the average pressure of liquid oxygen and the corresponding saturation temperature. In order to maintain the heat transfer temperature difference of the condensing evaporator, it is necessary to increase the pressure of the lower tower. From this point of view, we do not want to make the plate unit too high.The packing fouling of spray cooling tower not only makes the air out of the tower easy to carry water, but also makes the air out of the tower temperature rise, which is unfavorable to the air separation production. Therefore, the water quality should be improved to make the spray water as clean as possible. In order to prevent scaling, try to reduce the temperature of the air entering the spray tower.
