DEAR Biogas purification unit.The cooling capacity is balanced, so the condensation capacity of gaseous nitrogen is larger than the evaporation capacity of liquid oxygen. Is there any liquid accumulating? No. Because liquid nitrogen is throttled to the upper tower and the pressure is reduced, part of it will be vaporized. Therefore, the amount of liquid nitrogen flowing to the condensing evaporator is still equal to the amount of liquid oxygen evaporation, and no liquid will accumulate.DEAR Biogas purification unit.There is a flow resistance when the gas flows through the switching heat exchanger. The resistance is usually expressed by the pressure drop of backflow gas, which is about 10KPA. The resistance is not only related to the amount of gas flow, but also related to the manufacturing quality of the equipment and the accumulation of water or carbon dioxide. Air leakage in the automatic valve box will also increase the resistance.If the heat transfer surface of the condensing evaporator is insufficient, its heat load will be reduced, that is, the heat transfer will be reduced. Therefore, the evaporation of liquid oxygen will be reduced, and the condensation of gas nitrogen will be reduced accordingly. This will directly affect the distillation conditions of the upper and lower columns. At the same time, the air intake of the lower tower will be reduced, the air can not be fed, and the oxygen production will be reduced.
When the external work W is consumed in the steam compressor 1 and the refrigerant is compressed to a certain pressure, the corresponding saturation temperature will be higher than the ambient temperature. When passing through condenser 2, heat Q1 is released to the cooling water, and then it is condensed into liquid. After throttling and depressurizing through throttle valve 3, part of the liquid is gasified, and with the decrease of pressure, the corresponding saturation temperature also decreases.DEAR Biogas purification unit.In the rectifying tower, the steam with higher temperature and the liquid with lower temperature contact each other continuously, the nitrogen in the liquid evaporates more and the oxygen in the gas condenses more, so that the nitrogen content in the rising steam increases continuously and the oxygen content in the downstream liquid increases continuously, so as to realize the air-gas separation.The oxygen content of liquid oxygen and liquid air in the air separation unit is high, which will cause the oxygen concentration to increase in local range after evaporation in the air. If there is a fire, there is a risk of combustion and explosion. A large amount of liquid oxygen was discharged into the trench in a chemical fertilizer plant, and the electric welding spark caused an explosion injury accident. Therefore, it is strictly forbidden to discharge the liquid into the trench at will, and it should be discharged into the liquid evaporation tank or special low temperature resistant metal discharge pit through pipeline.
The refrigerating capacity provided by the refrigerator is usually precooled by the low-temperature working medium of the refrigerator in the air separation unit purified by molecular sieve, so as to improve the adsorption purification effect. This is the cooling capacity provided by the outside of the air separation unit, which refers to the heat carried away by the chilled water from the air. It can reduce the required throttling effect and the cooling capacity of the expander.DEAR Biogas purification unit.The refrigeration capacity of the expander is determined according to the cooling capacity demand of the whole air separation unit. In the start-up stage, in order to make the device cool and accumulate liquid as soon as possible, an additional expander is often used to increase the expansion air volume to increase the total cooling capacity.When there is liquid in the storage tank, it is strictly forbidden to use hot work for repair; the thawing of equipment pipeline should be heated slowly, and do not use overheated working medium or open fire to thaw; protective gloves should be worn when contacting low-temperature liquid to avoid direct contact between skin and low-temperature liquid; the transportation process should be stable, and there should be no big bumps.
