DEAR Air separation plant.For example, when the pressure before throttling is 4.5MPa and the temperature is reduced to 145K (- 128 ℃), the specific enthalpy will be less than the specific enthalpy of the above saturated steam. After throttling, the state point falls in the wet steam area, indicating that some liquid air has been generated.Under the action of gravity, the liquid flowing to the trough flows down rapidly along the trough and is discharged along the longitudinal groove, so that the condensation heat transfer coefficient is significantly improved. After the new condensing evaporator (copper) is used in 150m3 / h air separation unit, the heat transfer temperature difference is reduced from 2.5 ℃ to 1.2 ℃, the heat transfer coefficient is increased from 600W / (M2 · K) to 1500W / (M2 · K), and the energy consumption is reduced by 5% ~ 7%.DEAR Air separation plant.There is a flow resistance when the gas flows through the switching heat exchanger. The resistance is usually expressed by the pressure drop of backflow gas, which is about 10KPA. The resistance is not only related to the amount of gas flow, but also related to the manufacturing quality of the equipment and the accumulation of water or carbon dioxide. Air leakage in the automatic valve box will also increase the resistance.
For safety, the impurities are removed in the purification device, such as molecular sieve adsorber. However, it can not be done for the self cleaning process of switching heat exchanger. Therefore, the following measures should be taken in the process design and operation: the volume fraction of acetylene and hydrocarbon in the raw material air should not exceed 0.5 × 10-6 and 30 × 10-5 respectively; liquid air adsorber should be installed to absorb harmful impurities;DEAR Air separation plant.Since the argon content in the air is constant, the argon content in the stripping section will decrease and the argon content in the distillation section will increase correspondingly. If the nitrogen production decreases, the nitrogen concentration will increase, and the argon rich section will move down. That is to say, the argon content in the argon rich region of the distillation section should be reduced, and the argon content in the argon rich region of the stripping section should be increased.
DEAR Air separation plant.It can be divided into three stages: cooling equipment, liquid accumulation and rectification condition adjustment. Compared with the start-up mode of switching process, it can be called "overall cooling method" or "one-time cooling method". Attention should be paid to the following points during the start-up operation: the molecular sieve used for the first time should be activated and regenerated to remove the water and carbon dioxide absorbed in the transportation and filling process.If the heat exchange effect of the air compressor end cooler (or nitrogen water precooler) is not good, or the cooling water temperature is high, the air temperature into the device will rise. If the air volume remains unchanged, the cooling capacity required to cool the air to near the liquefaction temperature will increase accordingly.DEAR Air separation plant.With the increase of air intake, the air pressure decreases and the upper tower pressure increases. Purity method. When a small amount of leakage occurs between the product oxygen and nitrogen channels and the air channel, it can be judged by the product purity analysis results, and the product purity of the switching heat exchanger decreases.
