DEAR Liquid air separation unit.The hot end temperature difference of small equipment refers to the difference between the temperature of high pressure air before entering the tower and the average temperature of reflux oxygen, nitrogen and distillate tower. It is 5 ~ 8 ℃ for general gas equipment and 8 ~ 12 ℃ for liquid equipment. The pressure difference before and after the heat exchanger refers to the difference between the pressure at the inlet of the dryer (or purifier) and the high pressure air pressure at the end of the heat exchanger. Under normal circumstances, this pressure difference is difficult to see on the high pressure gauge.Under the condition of constant water vapor content, due to the decrease of temperature, the original unsaturated water vapor in the air can become saturated vapor, and the excess water will be separated out. The temperature at which water vapor reaches saturation is called the dew point.DEAR Liquid air separation unit.Palladium plating on activated alumina. In this way, oxygen and hydrogen can be directly combined into water, and the crude argon containing 1% - 3% oxygen can be reduced to 0.15 × 10-6 without additional heat source. Moreover, the production of catalyst is more convenient and the price is cheaper. However, this method requires strict control of oxygen content and excess hydrogen in crude argon, otherwise the effect of oxygen removal will be affected or the catalyst will be burned.
DEAR Liquid air separation unit.The so-called nitrogen water precooler with water, generally refers to the air out of the spray cooling tower with too much water fault. The air cooling tower cools the air through direct contact between air and water. Theoretically, the moisture content of the air out of the tower is the corresponding moisture content of the saturated air at that time.DEAR Liquid air separation unit.The pipe is filled with both air and backflow gas, so the temperature of hot blowing period (filled with air) and cold blowing period (filled with backflow gas) can be measured. The cold end temperature is measured at the bottom of the accumulator with a resistance thermometer. The following describes how to measure the temperature condition of the accumulator and calculate the temperature difference between the hot end and the cold end with some measured data.In addition, helium is the best refrigerant for cryocooler. Helium liquefier and helium refrigerator can obtain low temperature close to absolute zero. The pump operated by liquid helium can reach 133.32 × 10-9pa high vacuum in electronic industry and 133.32 × 10-10 ～ 133.32 × 10-12pa ultra vacuum in space research.
Under the same pressure, the saturation temperature of nitrogen is lower than that of oxygen. Under the standard atmospheric pressure (0.1013mpa), the liquefaction (gasification) temperature of nitrogen is - 195.8 ℃, and the liquefaction (gasification) temperature of oxygen is - 183 ℃. However, the saturation temperature is pressure dependent and increases with the increase of pressure.With a large amount of oxygen condensing, the oxygen content in gas phase decreases, and the argon condensing relatively increases. Therefore, the argon content in gas phase gradually decreases, and it is only 0.0% after reaching the top of the tower. Because oxygen and argon are difficult to volatilize to nitrogen, they condense into liquid phase more than nitrogen, so the concentration of oxygen and argon in liquid phase is higher than that in gas phase.In the rectifying tower, the steam with higher temperature and the liquid with lower temperature contact each other continuously, the nitrogen in the liquid evaporates more and the oxygen in the gas condenses more, so that the nitrogen content in the rising steam increases continuously and the oxygen content in the downstream liquid increases continuously, so as to realize the air-gas separation.
