The relationship between the refrigeration capacity of expander and various factors is as follows: the larger the expansion capacity is, the larger the total refrigeration capacity is. However, for the low-pressure air separation unit, the expansion air is directly sent to the upper column to participate in the distillation, too much expansion air will affect the distillation effect. This is what the separation process does not want.DEAR Cryogenic air separation unit.The purpose of purging after heating the fractionator is to remove the mechanical impurities in pipes and vessels. The blowing out steps are as follows: the preparation before blowing out: close the main inlet valve of heating air and all heating valves, open the blowing out valve of oil-water separator of purifier at the same time, loosen the ejector rods of inlet and outlet valves of expander, close the on-6 valve, pull open the stem of joint-1 valve, open the blowing-1 valve, blowing-2 valve and high pressure gauge valve, and close the blowing out valve of oil-water separator of purifier;
High heat transfer efficiency, large heat transfer area per unit volume, about 2500 m3 / m3. Moreover, due to the direct heat exchange between cold and hot fluids, it is basically a stable heat transfer process, which can ensure the stability of working conditions in the tower. The temperature of air flow and packing in the accumulator will change periodically with the switching time, which is an unstable heat transfer process;DEAR Cryogenic air separation unit.If the temperature of the product channel and circulation channel in the middle of the switching heat exchanger is uniform, and the temperature deviation in the middle of other channels is very large, it is due to the bias flow caused by insufficient air volume. It is necessary to try to increase the air intake volume, which is generally used in rough adjustment. The product oxygen and nitrogen are backflow gases. Changing their flow distribution can also achieve the purpose of adjusting the temperature condition.For the gas channel, it is better to select high and thin fins and increase the heat transfer area to make up for the lack of surface heat transfer coefficient. Now the fin specifications have been finalized. For example, there are mainly two kinds of serrated fins: 9.5mm high and 0.2mm thick for gas passage; 4.7MM high and 0.3mm thick for liquid passage. The wing spacing tends to be smaller, and 1.4mm is usually used.
It can make the accumulator pass through the freezing stage of water and carbon dioxide more quickly, prevent water and carbon dioxide from entering the distillation tower more effectively, shorten the working time of expander in the precipitation stage of water and carbon dioxide, and reduce the possibility of water and carbon dioxide freezing and blocking the expander.The corresponding model of the equipment matched with the air separation unit has also been compiled. For example, the model of fractionator: fon-6000 / 13000 means: f-fractionator: on oxygen and nitrogen products; 6000 - oxygen production, m3 / h; 13000 - nitrogen production, m3 / h. Model of liquefaction equipment: ypon -- 200 / 300 means y-liquefaction unit; p-expander; on oxygen nitrogen product; 200 liquid oxygen output L / h; 300 liquid nitrogen output L / h.The proportion of neon and helium in air is very small, the volume fraction of neon in air is 15 × 10-6 ~ 18 × 10-6, and the volume fraction of helium in air is 4.6 × 10-6 ~ 5.3 × 10-6. Because their liquefying temperature is lower than that of nitrogen, neon and helium in the lower tower will not condense when they rise to the upper part of the condensing side of the main condensing evaporator (i.e. at the main cooling top cover).
