The classical single column process is the first one to be used in industrial application. However, there are many disadvantages in the classical single column process. One is that oxygen and nitrogen cannot be produced simultaneously, and the other is that the oxygen extraction rate can only reach about 70%. There are two improvement schemes to solve the defects of classical single column process. One is the current double column process. Firstly, the pressure air is separated into liquid nitrogen and oxygen rich liquid space by condensation distillation in a column with condensation, and then the oxygen gas and nitrogen are produced simultaneously by distillation and separation in atmospheric distillation column. Another improvement is to add a heat pump distillation system with nitrogen as the circulating working medium in the distillation section of classical single column process. It can also be used to produce oxygen and nitrogen products and improve the oxygen extraction rate.
In order to achieve the product plan with low liquid product quantity in small air separation units and large air separation units, it is necessary to adjust the process plan of the new single column process to reduce the air quantity through expander to reduce the expansion refrigeration capacity under the condition of keeping the expansion refrigeration efficiency basically unchanged, or increase the refrigeration capacity required by the air separation unit.
The product plan of air separation unit is given, and it can not be adjusted arbitrarily. The product plan of air separation unit not only includes the quantity and purity of oxygen, nitrogen and argon gas, but also the quantity and purity of liquid products. The purity of liquid products is close to that of gas products, but the quantity of liquid products is a big problem. The process plan of air separation unit will have a significant impact.
The new single column process is different from the double column process. Air distillation is undertaken by nitrogen heat pump compressor, air oxygen air heat pump compressor and crude argon heat pump compressor, while air compressor only undertakes the function of air raw material transportation and expansion refrigeration. If the outlet pressure of air compressor is the same as that of double column process air compressor, the expansion refrigeration capacity is not only used to compensate for the temperature difference at the heat end and air separation device, The liquid product can reach about 25% of the oxygen output of the air separation unit. The energy consumption of gas products is less than 20% than that of double column process after deducting the energy consumption of liquid products.
DEAR Air Separation has a number of patent technologies, of which two ultra-low pressure energy saving patents are the leading domestic level, which can reduce the energy consumption of biogas purification unit by 5% - 15%, and save operation costs.
