For 1000m3 / h such a small low-pressure air separation plant, when producing gaseous products, the required expansion air volume has reached 28% of the processing air volume, and it can not all enter the tower to participate in distillation. If some liquid products are to be produced, more expansion air will be needed, and more expansion air will be bypassed to the heat exchanger.DEAR Air separation plant.Safety valve is divided into spring type and lever type. The seal of spring type safety valve disc and valve seat depends on the force of spring, while the seal of lever type safety valve relies on the force of heavy hammer through lever. The spring type safety valve changes the compression degree of the spring through the upper adjusting screw, and the take-off pressure increases when the spring is compressed.In order to check the perpendicularity next time, the shell of the tower (6-7m above the ground) is welded with a correction iron with a hole of 1 mm, the heavy vertical line is hoisted, the correction iron plate is welded at 150 mm above the ground, and a point is made on the correction plate at the vertical center for future inspection.
DEAR Air separation plant.The evaporation technology has been applied in the imported 72000m3 / h and 20000m3 / h air separation units. However, in recent years, although molecular sieve purification process has been adopted in large air separation plants at home and abroad, there are still several main cooling explosion accidents. The exact cause of the explosion has not been found out, but membrane evaporation seems to increase the possibility that hydrocarbons dissolved in liquid oxygen may precipitate on the heat transfer surface during evaporation.DEAR Air separation plant.Generally, the whole system pressure test in the installation of air separation unit refers to the latter. The pressure level and test method of air tightness test are different according to the tested object, and shall be carried out according to the technical documents of the manufacturer. Generally, after the installation of the air separation unit, the pressure test of the whole system should be carried out and the residual rate should be calculated. The residue rate should be above 95%.
DEAR Air separation plant.Make up pebbles can be added from the pebble make-up port at the upper part of the accumulator without stopping. The filling ports are equipped with sealing devices to prevent air leakage and cooling during filling. Before filling, pebbles should be cleaned to prevent weeds, silt and other debris from entering the accumulator, affecting heat transfer and increasing resistance.Before heating the device, the air cooling tower and water cooling tower should be separated from the device with blind plates; the oxygen content in the air cooling tower and water cooling tower should be analyzed. Only when the oxygen content is between 19% and 21%, can the maintenance personnel be allowed to enter; if they work in the area with oxygen content lower than 19%, they must be supervised by someone and wear isolation masks (oxygen respirator, long tube mask, etc.).DEAR Air separation plant.If the cold end temperature is too low, the air will start to liquefy somewhere in the cold section, and the cold end air temperature will not decrease. At this time, the temperature difference at the cold end will further expand and the temperature in the middle will decrease. The reason for the further expansion of the temperature difference at the cold end is that the temperature of the backflow gas rises continuously when it passes through the cold end, while the temperature of the air is almost unchanged after partial liquefaction.
In our daily life, we can see that a cup of hot water will naturally cool to the ambient temperature, and a piece of ice will naturally melt into water in the environment above 0 ℃. But water doesn't spontaneously drop to a lower temperature than the surrounding air and freeze. These phenomena show a basic law of nature: heat can only be transferred spontaneously from high-temperature objects to low-temperature objects, but the opposite process cannot be carried out spontaneously.DEAR Air separation plant.If the nitrogen purity at the top of the lower tower is improved, the temperature at the nitrogen side will be reduced, the temperature difference between the main cooling system and the evaporation of liquid oxygen will be reduced, and the rising speed of liquid level will be accelerated. When the liquid oxygen level rises to a certain extent, the heat load of the main cooler increases gradually. If the regulating valve-1 continues to be closed, the liquid nitrogen level in the main cooling system will be too high, which will affect the heat transfer of the main cooling system, and the air volume will not be able to enter.
