DEAR Air separation equipment.Entropy, like temperature, pressure and enthalpy, is also a physical quantity reflecting the internal state of matter. It can't be measured directly with instruments, it can only be calculated, so it's more abstract. Sometimes it is convenient to use the concept of entropy in theoretical analysis.If the temperature difference at the hot end of each backflow gas is equal, the sum of their air volume is equal to the positive flow air volume. When the temperature difference at the hot end increases by 1 ℃, the incomplete heat exchange loss will increase by 1.31kj/m3, which will increase the total cooling loss by more than 10%. Therefore, it is of great significance to reduce the total cooling loss of the device by reducing the temperature difference at the hot end as much as possible. Especially when it is found that the temperature difference at the hot end is larger than the specified value, we should pay attention to find out the reasons and take corresponding measures.
DEAR Air separation equipment.When the scale is serious, it must be removed. The cleaning methods are usually mechanical or acid washing. The mechanical method is to brush off the scale with an iron brush; the pickling method is to use the dilute solution containing 10% hydrochloric acid to clean with a small water pump, dissolve and remove the scale with acid (because the scale is generally alkaline), and then neutralize it with alkali. It should be noted that the acid should not be too thick to avoid corrosion of metal.DEAR Air separation equipment.Although the heat capacity of fins and baffles is very small, they still have some influence. The results show that the temperature changes greatly in 2-3 minutes after switching, and the other parts of the temperature are basically unchanged most of the time. Therefore, when measuring the temperature of air and sewage nitrogen and calculating the temperature difference between the hot end and the cold end, it is better to measure the temperature before switching as the same as the accumulator.
DEAR Air separation equipment.The crude argon produced by distillation of argon fraction in crude argon column contains 95% ～ 98% argon, 1% ～ 3% oxygen and 3% ～ 5% nitrogen. In order to produce refined argon, oxygen and nitrogen need to be further purified. The most commonly used method of crude argon deoxidization is to add a certain amount of hydrogen, make oxygen and hydrogenate to synthesize water through catalyst, and then to achieve the purpose of clean removal through dryer.In order to maintain the dryness of the heated gas after leaving the purifier, it is necessary to switch every 4h, but the regeneration time after switching is too late; if it is not switched in time, the service time will exceed 4h, and the moisture content of the heated gas after leaving the purifier will increase, thus affecting the heating effect of the fractionator.DEAR Air separation equipment.The gas source for the test shall be oil-free, dry air or nitrogen, and the pressure shall be higher than the maximum pressure of the heat exchanger. The pressure gauge used in the test shall be calibrated accurately and avoid oil. The accuracy shall be higher than 1.5. The dial diameter shall be greater than 100 mm. The scale on the dial shall meet the requirements of measurement value (the measurement value shall be between 1 / 3 and 2 / 3 of the dial). The inlet flange of high pressure air and outlet flange of oxygen, nitrogen and fraction are sealed with blind plate, and the inlet and outlet of expander can be closed tightly with valve. Remove the safety valve and replace the plug for pressure test.
DEAR Air separation equipment.In normal operation, the biggest influence on the operation cycle is the temperature difference control of the cold end of the switching heat exchanger. If the temperature is not well controlled, on the one hand, the self-cleaning effect of the switching heat exchanger will be poor, and carbon dioxide will accumulate in the heat exchanger and increase its resistance; on the other hand, a small amount of carbon dioxide will be brought into the tower.The main heat exchanger and condensing evaporator play a key role in the production of liquid in air separation plant. The main heat exchanger uses the low-temperature and low-pressure gas after expansion as the backflow gas of the heat exchanger to cool the high-pressure positive flow air, so that its temperature before expansion is gradually reduced. At the same time, the temperature after expansion will gradually decrease to a lower level until the temperature required for liquefaction is reached, which makes the positive air partially liquefied. The cooling process of air separation unit in the start-up stage is such a gradual cooling process.
