Plate fin type is widely used in various air separation plants, mainly used in medium and large air separation plants. It is the condensation and evaporation of gaseous nitrogen and liquid oxygen in the adjacent channels. The adjustment of their heat load should be carried out according to their different working principles.The middle pumping volume should be small at the beginning. For the 6000m3 / h oxygen generator, 200m3 / h can be pumped first. With the continuous decrease of the temperature of the intermediate extraction, the gas extraction volume is gradually increased. Increase 500m3 / h each time, so that the temperature at the bottom of the accumulator does not rise sharply and the outlet temperature of the expander is not lower than - 180 ℃.DEAR Air separation equipment.When the temperature is constant, the partial pressure of water vapor in saturated air (that is, the saturated pressure of water vapor at that temperature) is a constant value, which has nothing to do with the total pressure of saturated air. In other words, regardless of the total pressure of saturated air, the mass content of water vapor in the same volume of saturated air is the same. Therefore, the higher the total pressure of the same mass of saturated air is controlled, the smaller the total volume and the less water (mass) contained in the saturated air.
When the pressure of the upper and lower towers is constant, the temperature difference between the main cooling tower and the main cooling tower will be reduced by increasing the purity of liquid oxygen, and the temperature difference between the main cooling tower and the main cooling tower will be reduced by increasing the purity of gas nitrogen. If the purity and pressure of gas nitrogen remain unchanged and the purity of liquid oxygen is constant, the temperature difference of condensing evaporator can be reduced by increasing the pressure of upper tower.DEAR Air separation equipment.According to the law of conservation of energy, the total energy (enthalpy) of the fluid before and after throttling should remain unchanged. However, each part of the three components of enthalpy: kinetic energy of molecular motion, potential energy of molecular interaction and flow energy may change.DEAR Air separation equipment.When the expander expands, the decrease of gas temperature is not only caused by the decrease of pressure, resulting in the increase of molecular potential energy, but also the decrease of molecular kinetic energy. It is mainly caused by external work, so the effect of temperature drop is much greater than that of throttling.
DEAR Air separation equipment.It is known from practice that as long as there is a temperature difference, the heat will be transferred spontaneously. Moreover, heat is always transferred from the fluid with higher temperature to the fluid with lower temperature. Temperature difference is the power of heat transfer. The heat transfer processes of three kinds of heat exchangers are different, but their basic rules are the same.DEAR Air separation equipment.Low temperature liquid evaporator has atmospheric type and steam water bath type. The atmospheric evaporator is composed of finned evaporation tubes, which are placed in parallel in several groups and have a large volume. With the flow of low temperature liquid, the surface of evaporation fin will be frosted gradually. The frost should cover the evaporator surface.The fundamental purpose of setting nitrogen water precooler is to reduce the temperature of air entering the air separation column and avoid the temperature fluctuation. Because the inlet air temperature directly affects the working conditions of the switching heat exchanger and the distillation column, as well as the economy of the whole air separation unit.
