When the liquid level increases, the flow velocity in the oxygen channel increases and the bubbles on the wall are continuously washed, which will improve the heat transfer coefficient of the evaporation side. For the heat transfer on the condensation side, the heat transfer coefficient is larger than that on the evaporation side, and the heat transfer coefficient is almost constant when the height of the plate unit is determined.When the gas is expanded by external power through the expander, the internal energy will be consumed, and the effect of temperature drop is much greater than when the throttle is not expanded by external power. Especially for the low pressure air separation plant, the refrigeration capacity mainly depends on the expander. However, the higher the inlet temperature is, the greater the effect is. In addition, no liquid is allowed in the expander to avoid damaging the blades.If the temperature of cold end reaches - 130 ℃ and the temperature of intermediate extraction is between 15 ℃ and 25 ℃, the CO2 adsorber will be easily blocked. At this time, it can be solved by frequently exchanging adsorbers.
DEAR Air separation unit.In the full low pressure oxygen generator, the butterfly valve is commonly used to regulate the flow of air, oxygen and nitrogen, the air volume of brake fan, etc., and the remote control electric butterfly valve is generally used. The opening indicated by the butterfly valve is expressed as 0% ～ 100%. Indicates whether the value is proportional to the flow rate. In fact, when the opening of the butterfly valve is small, the flow changes greatly when the opening of the butterfly valve is changed;DEAR Air separation unit.According to the characteristics of throttling process, the energy (enthalpy) before and after throttling remains unchanged, but the corresponding saturation temperature also decreases due to the decrease of pressure after throttling. The specific enthalpy (H ′ 2) of low-pressure saturated liquid is smaller than that before throttling. Therefore, some liquid (y) must be gasified into low-pressure saturated steam, and its enthalpy value is h ″ 2, so that the sum of energy of gas and liquid remains unchanged. That is: H1 = (1-y) H ′ 2 + YH ″ 2, y = (h1-h ′ 2) / (H ″ 2-h ′ 2).
DEAR Air separation unit.The temperature of intermediate extraction is related to the balance of cooling capacity. If we need to increase the cooling capacity, that is to say, increase the expansion capacity, the temperature of the central extraction will decrease. When there are several groups of parallel plate fin heat exchangers working, the temperature of the central extraction can be maintained by the control valve of the large group: the group with higher temperature can be opened larger, otherwise it can be closed smaller.DEAR Air separation unit.In terms of self-cleaning performance, the fin structure has good self-cleaning characteristics, which is better than the accumulator; the heat capacity is small, which can shorten the start-up time; the equipment volume is small, the switching cycle is long, the switching loss is small, and the resistance is small.DEAR Air separation unit.Condensation is the reverse process of evaporation. For pure matter, the condensation temperature is also called liquefying temperature, which is equal to the evaporation temperature under the same pressure. The saturation temperature can unify them.
