Why are acetylene the most dangerous substance in DEAR air separation equipment parts?
When water enters the cold accumulator (or switching heat exchanger) to freeze and block the channel, the resistance will be greatly increased, the upper tower pressure and the exhaust pressure of the air compressor will be increased, the switching sound will become dull and elongated, and a large amount of water gas can be seen in the waste nitrogen discharge pipe. These phenomena can be used to judge the water inflow accident of the cold accumulator (or switching heat exchanger).For the DEAR air separation unit with liquid air subcooler, part of the liquid in the lower tower and main cooler should be drained before starting to prevent the liquid air subcooler from blocking; when the temperature of the cold end reaches - 150 ℃, the circulating flow should be reduced as far as possible to prevent the circulation channel from being blocked by carbon dioxide;In the cold section of the switching heat exchanger, carbon dioxide has been basically removed theoretically, but due to the entrainment effect of the gas flow, the amount of carbon dioxide brought into the tower is much more than the theoretical content. In addition to being partially removed by the adsorption filter, the rest of the carbon dioxide will gradually accumulate in the tower and block the tray, pipes and valves.
The drying zone is between - 60 ℃ and - 133 ℃. Based on this principle, the cooling process of equipment in start-up operation is divided into stages, which is called stage cooling method. The whole cooling process is divided into four stages: the first stage is water analysis and freezing stage.Water is sprayed from the top of the tower to contact and mix with the air to cool the air. A plurality of cross flow sieve plates or fillers are arranged in the air cooling tower to increase the gas-liquid contact area. In order to separate the water, a water capture layer is set on the top of the tower. When the air flow rate in the air cooling tower is too fast, the water carrying or spraying amount is too much, and the water level automatic regulation fails, the water inflow accident of Molecular Sieve Purifier will occur.This kind of regulation method is only effective when the on-6 valve is closed very small (within one revolution) and the high pressure air pressure is not equal to the pressure in front of the expander. And each adjustment can only rotate 3-5 degrees, not too large.
There are two ways of blowing: continuous blowing and intermittent blowing. The so-called "continuous blowing" is the blowing method that the blowing valve is always open for a period of time. The so-called "intermittent blowing" means that the blowing valve is closed and opened when it is closed, and then it is suddenly opened after holding high pressure when it is closed and repeated. This method has a good effect on removing solid impurities and free water. Because the pressure difference increases when the pressure is held, the air flow speed increases when the blow off valve is opened, and the impact entrainment effect is enhanced.The valve stem falls off. The reasons are: the fixed split pin is broken, the nut is loose, falls off, and the spring is broken. The fixing bolt falls off, causing the whole automatic valve to fall off. ）The valve stem is broken. The main reason is that the material of the valve stem is poor and the manufacturing is defective. Or the spring is too hard, the valve stem is under too much force in the process of opening and closing.