DEAR Cryogenic air separation unit.The amount of oxygen running away with sewage nitrogen is 18100 (m3 / h) × 60.2 /% × 5.5% = 599.2m3/h. If the oxygen content in sewage nitrogen increases to 7.5%, the amount of oxygen running away with sewage nitrogen is 18100 (m3 / h) × 60.2% × 7.5% = 817.2m3/h. Therefore, the oxygen production will be reduced by (817.2-599.2) m3 / h = 218m3 / h, that is, (3200-218) m3 / h = 2982m3 / h.DEAR Cryogenic air separation unit.With the development of large-scale air separation plant, the heat transfer area of the main condensing evaporator is also increasing. If the tube type is used, the number of tubes will be more than 20000, which brings great difficulties to the manufacturing. At present, the plate fin type has been completely replaced.DEAR Cryogenic air separation unit.The temperature of intermediate extraction is related to the balance of cooling capacity. If we need to increase the cooling capacity, that is to say, increase the expansion capacity, the temperature of the central extraction will decrease. When there are several groups of parallel plate fin heat exchangers working, the temperature of the central extraction can be maintained by the control valve of the large group: the group with higher temperature can be opened larger, otherwise it can be closed smaller.
Condensing evaporator generally refers to the average heat transfer temperature difference between gas nitrogen and liquid oxygen. It is based on the different boiling points (saturation temperatures) of oxygen and nitrogen at different pressures and purities. Therefore, the temperature difference of condensing evaporator is affected by the purity of oxygen and nitrogen and the pressure change of upper and lower tower.DEAR Cryogenic air separation unit.Fin is the most basic element of plate fin heat exchanger, its function is to increase the heat transfer area. In fact, when the heat is transferred from the hot fluid to the cold fluid through the baffle, because the area of the fins is much larger than that of the baffle, most of the heat is transferred from the baffle to the fins first, and then from the fins to the cold fluid. Only a small part is directly through the diaphragm to complete. At the same time, the clapboard also supports and reinforces the clapboard to form an organic whole and increase its strength.
Special attention should be paid to the liquid discharge pipeline to prevent the increasing cold loss caused by the continuous gasification of liquid. The outlet pipe should be inclined upward, and an upward bend should be made within 800mm near the cold insulation box, with the height of about 6-10 times of the diameter, but not less than 200 mm. When the valve is closed, a liquid seal is formed, and the liquid will not continuously flow to the valve side for gasification. Some of the liquid discharge pipe with heating sleeve, in order to prevent freezing;With the increase of air intake, the air pressure decreases and the upper tower pressure increases. Purity method. When a small amount of leakage occurs between the product oxygen and nitrogen channels and the air channel, it can be judged by the product purity analysis results, and the product purity of the switching heat exchanger decreases.A cooler is added at the end of the turbine air compressor to reduce the air temperature below 100 ℃ before entering the spray tower. The packing ring and water separation device should be inspected, cleaned or replaced regularly. The maintenance of the liquid level self regulating device should be strengthened to ensure the normal indication of the water level gauge and the accurate and reliable action of the automatic water level regulating valve. Even if the self-regulation is put into operation, the water level should be checked frequently and strictly controlled within the specified range.
