DEAR Air separation equipment.The average temperature difference is related to the relative flow direction of cold and hot fluids. The parallel flow of two fluids in the same direction is called "forward flow"; the parallel reverse flow is called "counter flow"; the vertical cross flow is called "cross flow". When the properties, flow rate, inlet and outlet temperature and heat exchange area of the cold and hot fluids are the same, the maximum average temperature difference between the cold and hot fluids is found in the counter flow arrangement, followed by the cross flow, and the minimum in the downstream flow.In order to avoid the increase of hydrocarbon concentration in liquid oxygen, according to the material balance, it is necessary to extract part of liquid oxygen from the main cooler and extract part of hydrocarbon from the main cooler. The minimum amount of liquid oxygen extracted is equal to 1% of the gas oxygen output, and then gasified separately.Shorten the adsorption cycle to ensure the work within the allowable range of adsorption capacity; pay attention to monitor the carbon dioxide content in the air at the outlet of the adsorber below 1 × 10-6. At the same time, reduce the product nitrogen flow properly, increase the nitrogen flow of decontamination nitrogen cooling tower to reduce the temperature of cooling water as much as possible, and increase the flow of common cooling water.
Because the temperature of bypass air is the saturation temperature under the tower inlet air pressure, which is basically unchanged, when the expansion volume increases, the temperature in front of the expander decreases, and the superheat after expansion decreases. If the expansion is within the allowable range of the upper column distillation potential, the oxygen extraction rate will be reduced. On the contrary, the temperature in front of the expander increases with the decrease of expansion.The argon fraction enters from the bottom, and the liquid at the bottom contains high argon, which returns to the main column for distillation. Therefore, only a part of argon in argon fraction is extracted as crude argon product, and the amount of argon fraction required is about 35-40 times of that of crude argon.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.
During short-term shutdown, if the cold blowing of regenerated molecular sieve adsorber is about to end, the regenerated molecular sieve adsorber can be manually switched; when the regeneration system of molecular sieve adsorber is adjusted to normal process conditions and the carbon dioxide content at the analysis point after molecular sieve is less than 1 × 10-6, the air is slowly introduced into the air separation tower; while adjusting the air separation condition, the molecular sieve regeneration can be slowly switched In addition, waste nitrogen is used to ensure the flow of regeneration gas.The internal reason for the phase transition is that when the temperature changes, the motion of the molecules that make up the material changes. When the temperature decreases, the molecular motion slows down, the distance between the molecules decreases, and the force between the molecules increases until the attraction increases to the liquid state. The temperature at this point is the liquefaction temperature. Since the liquefaction temperature of air under atmospheric pressure ranges from - 191.3 ℃ to - 194.3 ℃, it exists in the form of gas at room temperature. However, as long as the temperature is low enough, air can not only turn into liquid, but also into solid.
