Flange connection is to fix two pipes, pipe fittings or equipment on one flange respectively, and then add flange gasket between the two flanges and fasten them together with bolts to complete the connection. Some pipe fittings and equipment have their own flange, which also belongs to flange connection. The flange is divided into threaded connection (threaded connection) flange and welding flange.DEAR Cryogenic air separation unit.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.
The number of water vapor molecules in space is less, and there are more water molecules in liquid that can run into space, which increases the number of water vapor molecules in space. At the same time, some water vapor molecules will run into the liquid. When the number of molecules leaving the liquid is equal to the number of molecules running back to the liquid, the number of vapor molecules in space will not increase, that is, the content of vapor reaches the maximum.DEAR Cryogenic air separation unit.For the liquid oxygen pump, the liquid oxygen at its inlet should be in the supercooled state, because if part of the liquid oxygen is gasified in the pump, the capacity of the pump will be reduced, and the liquid oxygen can not be smoothly transported to the main cooler. When the pressure of the upper tower drops too much, the temperature of the liquid oxygen at the inlet of the liquid oxygen pump will exceed the saturation temperature corresponding to the pressure, resulting in the gasification of part of the liquid oxygen and the "entrainment" phenomenon, so that the liquid oxygen can not be sent out, resulting in the rise of the liquid level at the bottom of the upper tower.
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.Therefore, the total cooling loss of an air separation unit that does not produce liquid products is 8.1-11.4kj/m3. It can be seen that most of the total cooling loss is made up by expander cooling, and the required expander cooling capacity is 6.74-10.04kj/m3, accounting for 83% - 88% of the total cooling capacity.If the pipe network is allowed to be shut down completely, the oxygen compressor can be used to depressurize and put into operation. This is simpler than the above-mentioned shutdown and commissioning methods of local pipelines or spherical tanks. In short, when opening the oxygen valve, attention should be paid to controlling the oxygen flow rate and the cleanliness of the pipeline behind the valve to prevent combustion, so as to achieve safe operation.
It represents the heat transfer capacity per unit area when the temperature difference between the two sides of the wall is 1 ℃, and its unit is w / (M2 ℃). The heat transfer coefficient reflects all the factors affecting the heat transfer except the heat transfer area F and the temperature difference △ t. Obviously, the larger the heat transfer coefficient K is, the stronger the heat transfer ability is. On the contrary, it is weak.After extracting argon fraction, it has a great influence on the working conditions from the liquid air feed port to the fraction extraction port of the main tower. Because the amount of rising steam decreases and the reflux ratio increases, more trays are needed to ensure the purity of liquid oxygen.The main fault in the valve body is that the sealing surface between the valve top and the valve seat is not tight, which causes the valve not to close. The most common is the O-ring rubber seal off. This is mainly related to the uncleanness of the bonding surface and the poor quality of the adhesive. In addition, there are foreign matters at the valve seat; the concave convex spherical washers at both ends of the valve stem and the valve top are too tight or too loose; the fixed nut is not tightened, resulting in the loosening of the valve top; the bending of the valve stem may cause the valve to close loosely.
