The efficiency of expander reflects the performance of expander. The more close to the ideal enthalpy drop, the higher the efficiency. The efficiency of medium pressure piston expander is 55% ～ 60%, that of low pressure turbine expander is over 80%, and that of new high efficiency turbine expander is over 85%.DEAR Biogas purification unit.The purpose of controlling low pressure during fractionator heating is to speed up fractionator heating. If the low-pressure pressure is not controlled, the heated gas will be discharged from the oxygen and nitrogen discharge pipes with small resistance, and the heating gas volume of small pipes with large resistance (such as analysis valve, level gauge valve, etc.) and expander parts is very small, which is easy to cause high temperature in some pipes and incomplete heating in some pipes.Only after the installation of equipment and process pipeline is ready, the inspection pipeline can be installed. Its installation quality will affect the accuracy of instrument measurement. During installation, attention should be paid to: all detection pipelines (except in the tower) should be installed with a movable joint or stop valve at one end of the measurement point for easy blowing and maintenance;
DEAR Biogas purification unit.The refrigeration capacity of the expander is determined according to the cooling capacity demand of the whole air separation unit. In the start-up stage, in order to make the device cool and accumulate liquid as soon as possible, an additional expander is often used to increase the expansion air volume to increase the total cooling capacity.The oxygen extraction rate was as follows: ψ = 2982 × 99.6 / (18100 × 20.9) = 0.718 = 71.8%. Therefore, efforts should be made to reduce the oxygen content in sewage nitrogen, so as to produce more oxygen and improve the oxygen extraction rate. The oxygen extraction rate of all low pressure distillation column was only 80% ～ 85% before, but now it has been increased to 90% ～ 95%, and the most advanced one can even reach about 99%.The ordinate is temperature T (k), and the abscissa is entropy S (kJ / KMOL · K). There are isobaric lines and isoenthalpy lines on the graph. According to the two parameters (temperature, pressure) can determine a state point, can find out the corresponding specific enthalpy and entropy. For example, when the inlet absolute pressure P1 of the expander is 3.0MPa and the inlet temperature is - 85 ℃ (T1 = 188k), the specific enthalpy H1 of this point can be found to be 4880kj / KMOL.
If the heat transfer surface of the condensing evaporator is insufficient, its heat load will be reduced, that is, the heat transfer will be reduced. Therefore, the evaporation of liquid oxygen will be reduced, and the condensation of gas nitrogen will be reduced accordingly. This will directly affect the distillation conditions of the upper and lower columns. At the same time, the air intake of the lower tower will be reduced, the air can not be fed, and the oxygen production will be reduced.In order to improve the distillation condition of the upper tower, it is mainly to control the amount of oxygen and nitrogen taken out. On the one hand, the removal amount of the two should be appropriate; on the other hand, the valve opening should be appropriate, so as to reduce the pressure of the upper tower as much as possible, which is conducive to distillation and improve the purity of waste nitrogen.DEAR Biogas purification unit.Switching heat exchanger with water will also shorten the operation cycle. It is usually caused by improper operation of nitrogen water precooler. However, the slight water inflow is often due to the neglect of the blowing out of the water separator and the discharge of the condensed water in the air main pipe of the switching heat exchanger.
