The amount of liquid air generated by the biogas purification equipment in the liquefier is less than 10%, that is, only a small amount of cooling capacity is transferred to the tower through the liquefier, and most of the remaining cooling capacity will be transferred to the switching heat exchanger, resulting in supercooling of the switching heat exchanger, decreasing the temperature in the middle and expanding the temperature difference at the hot end. The regeneration of waste nitrogen is insufficient. If the temperature is increased by 1 ℃, the energy consumption of air separation equipment will increase by about 2%. Reducing the air temperature into the tower can not only improve the economy of the air separation plant, but also reduce the saturated moisture content in the air. For example, when the absolute pressure of air is 0.6MPa and the air temperature is reduced from 40 ℃ to 30 ℃, the saturated moisture content in every 1kg of air will be reduced by about 40%.

因旁通空气的温度为进塔空气压力下的饱和温度，基本不变，所以当膨胀量增加时，膨胀机前温度下降，膨胀后过热度减小。如果膨胀量在上塔精馏潜力允许的范围内，仍可全部送入上塔，则会使氧的提取率降低。反之，膨胀量减少则膨胀机前的温度提高。沼气提纯设备贮氧球罐每隔两年至少应进行一次内部检查，每隔5年测定一次壁厚。对腐蚀严重者，应缩短上述检查年限，并采取防腐措施。在罐的内壁可涂以长期耐腐蚀的无机富锌涂料(由锌粉和水玻璃为主配制而成)。设置在北方地区的球罐，在冬季停产时应降压或卸压，以降低罐壁的工作应力。

Because the temperature of bypass air is the saturation temperature under the air pressure into the tower, which is basically unchanged, when the expansion amount 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 distillation potential of the upper tower, it can still be sent to the upper tower, which will reduce the extraction rate of oxygen. On the contrary, if the expansion amount decreases, the temperature in front of the expander increases. The oxygen storage spherical tank of biogas purification equipment shall be internally inspected at least once every two years, and the wall thickness shall be measured every five years. For those with serious corrosion, the above inspection years shall be shortened and anti-corrosion measures shall be taken. The inner wall of the tank can be coated with long-term corrosion-resistant inorganic zinc rich coating (mainly prepared from zinc powder and water glass). For spherical tanks set in the north, the pressure shall be reduced or relieved when they are shut down in winter, so as to reduce the working stress of the tank wall.

沼气提纯设备传热量与传热面积成正比，而保冷箱的表面积并不与装置的容量成正比，所以，随着装置容量的增大，相对于每立方米加工空气的跑冷损失(单位冷损)是减小的。对一些采用管式蓄冷器的旧型空分装置，相同容量的制氧机在保冷箱内的设备多，相对来说表面积要大，跑冷损失也会大一些。沼气提纯设备调节中部温度的方法主要是调整正、返流气量的比例关系。常用的有：改变中抽气量或环流量；改变蓄冷器(或切换式换热器)各组间空气进气量的分配，或产品氧、氮气量的分配等。例如，中部温度偏高，可关小空气进口阀，减少空气进气量或增加环流量(或中抽量)。

The heat transfer of biogas purification equipment is directly proportional to the heat transfer area, while the surface area of the cold box is not directly proportional to the capacity of the device. Therefore, with the increase of the capacity of the device, the cooling loss per cubic meter of processing air (unit cooling loss) is reduced. For some old air separation units with tubular cold accumulators, oxygen generators with the same capacity have more equipment in the cold insulation box. Relatively speaking, the surface area is larger and the cooling loss will be larger. The method of adjusting the central temperature of biogas purification equipment is mainly to adjust the proportional relationship between positive and backflow gas. Commonly used are: changing the medium extraction volume or ring flow; Change the distribution of air intake between groups of cold accumulator (or switching heat exchanger), or the distribution of product oxygen and nitrogen. For example, if the temperature in the middle is too high, turn down the air inlet valve to reduce the air intake or increase the ring flow (or intermediate extraction).