DEAR Air separation equipment.When pressure test and leakage test, if such leakage is found, it is better to pull out the valve stem, re tin and tighten it, and silver welding is preferred. In the normal operation of the air separation plant, the cryogenic valve is an equipment that should be maintained frequently. We should have high standards, strict requirements, careful maintenance and good use.The flange connection is easy to use and can bear large pressure. Flange connection is widely used in industrial pipeline. In the family, the pipe diameter is small, and it is low pressure, and the flange connection is invisible. If in a boiler room or production site, there are flange connected pipes and equipment everywhere.DEAR Air separation equipment.Safety valve is an automatic valve, its function is to ensure that the machine or equipment will not be damaged due to overpressure. When the working pressure P ≥ 0.6MPa, the take-off pressure of the safety valve should be 1.05 ~ 1.1 times of the working pressure; when the working pressure P < 0.6MPa, it should be 1.2 ~ 1.25 times of the working pressure.
Attention should be paid to the following points when degreasing: degreaser with oil content less than 50mg / l can be used as net degreasing agent, degreaser with oil content in the range of 50-500mg / l can only be used for crude degreasing, and then it must be cleaned again with net degreaser. If the oil content is more than 500 mg / L, it must be distilled and regenerated, and the oil content must be tested before it can be used for degreasing;The amount of pure liquid nitrogen supplied by the lower tower to the upper tower is less, so a stream of dirty liquid nitrogen can be extracted to the upper tower, which increases the reflux ratio of the upper tower distillation section and has greater distillation potential, so as to allow more expanded air to enter the upper tower, so as to prevent the bypass of expanded air and affect the oxygen extraction rate.The lower tower needs a larger reflux ratio to ensure the quantity and purity of pure liquid nitrogen, and then it is sent to the upper tower as reflux liquid. In this process, the unit cooling capacity of the expanded refrigerant is higher, and the expansion capacity is smaller on the premise of compensating the same cooling loss.
The "on-off-on" operation method is actually an effective operation method to shorten the start-up time of the air separation unit by properly distributing the cooling capacity to make the main cooler accumulate liquid as soon as possible. In the start-up stage, the main cooling liquid level can not rise, on the one hand, the main cooling did not pre cool through;Inter wall type: the cold and hot fluids are separated by the heat transfer wall, and do not contact each other in the heat transfer process. Heat is transferred from the hot fluid to the cold fluid through the wall, such as tubular and plate heat exchangers. Heat storage type: the cold and hot fluids flow alternately through the solid heat storage body with sufficient heat capacity, the heat storage body absorbs heat when the hot fluid flows, and the heat storage body releases heat when the cold fluid flows, so as to realize the heat exchange between the cold and hot fluids.If the ratio of backflow to positive flow is smaller than the normal value, for example, if the annular flow is reduced or the pumping capacity is reduced, the positive flow air volume is more than the backflow air volume, and the cooling capacity absorbed by the positive flow air is more than that released by the backflow gas, that is, if the cooling capacity is insufficient, the temperature of the air out of the accumulator will rise, resulting in a larger temperature difference at the cold end.
