In the cooling phase of small air separation unit, the lower the expander outlet temperature the better, while ensuring that no liquid appears at the expander outlet. The operating point is also determined according to the outlet pressure and outlet temperature of the expansion.
In the accumulation of liquid and oxygen, nitrogen purification stage, all equipment in the cold box when further cooling, air began to liquefy, the lower tower began to appear liquid-air liquid level, followed by the main condensing evaporator into work, and will gradually output liquid, on the upper and lower tower distillation working conditions gradually established, and then can gradually increase into the tower (into the lower tower) processing air volume. When the main condensing evaporator liquid oxygen level reaches 80% of the normal liquid level, you can start to adjust the product purity. At the same time make good liquid oxygen pump pre-cooling work. When the liquid oxygen level rises and reaches the design level, the liquid oxygen pump can be started. The liquid oxygen pump gradually increases the output of liquid oxygen through frequency conversion, and the relative stability of the liquid oxygen level should be maintained. Adjust the oxygen venting valve to gradually make the oxygen pressure reach 3.0 MPa. as the high pressure air from the booster end of the turbine expander gradually liquefies, the outlet pressure of the booster compressor remains stable.
During the liquefaction phase, the inlet temperature of the expander is lowered as much as possible to increase the cooling capacity, while ensuring that the turbine outlet is not liquid.
Dear Air Separation has many years of experience in the manufacture of small air separation units，large air separation units and liquid air separation plants, and each piece of liquid air separation plants has technical research and design theory to ensure the safety and quality of the small air separation units.
