CO cryogenic separation system and method using nitrogen cycle

Abstract

The invention discloses a CO cryogenic separation system using nitrogen cycle. The CO cryogenic separation system comprises a main heat exchanger, a cryogenic separator, a hydrogen stripper, a demethanizer, a denitrogenation tower, a condensing evaporator and a cycle nitrogen compressor. The invention further discloses a CO cryogenic separation method using nitrogen cycle, wherein the CO cryogenic separation method comprises process steps of heat exchange, dehydrogenation, demethanation, denitrogenation, nitrogen compression refrigeration cycle and the like. The CO cryogenic separation system and method provided by the invention have beneficial effects that a nitrogen cycle compression and refrigeration process is adopted to fully play roles of high efficiency and low investment of a nitrogen compressor; the condensing evaporator is arranged to cleverly integrate the demethanizer and the denitrogenation tower, so as to greatly reduce power consumption of distillation; an operation pressure of a distillation tower is increased or a CO liquid pump is provided for replacing a CO compressor so as to meet pressure requirements of CO products; start-up and purification time of the device can be shortened and a venting amount at a start-up stage can be reduced; the system and the method has advantages of low energy consumption, fast start-up, investment saving and less emission, are in line with a general trend of energy conservation and consumption reduction, and have good economic and environmental protection benefits.

Description

technical field [0001] The invention relates to the field of cryogenic gas separation, in particular to a CO cryogenic separation system using nitrogen circulation and a method thereof. Background technique [0002] CO is an important raw material gas for oxo synthesis, and almost all organic chemicals can be prepared from CO. At present, the synthesis gas for producing CO mainly comes from pressurized coal gasification or natural gas / naphtha steam reforming. In addition to CO and hydrogen, the synthesis gas produced by coal gasification also contains a small amount of methane, nitrogen and argon. In view of the very high purity requirements (≥98.5%) of raw material CO in the production of chemical products such as ethylene glycol, acetic acid and dimethyl diamide, it is necessary to mix hydrogen, methane, nitrogen and argon in the synthesis gas remove. Cryogenic separation technology has mature technology, stable operation, large processing capacity, high product purity a...

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Problems solved by technology

[0003] Chinese invention patent CN 100427862 C "method and equipment for producing carbon monoxide by low-temperature distillation" and CN101823709 B "separation of carbon monoxide from a gas mixture containing carbon monoxide" both use pure CO Compression and refrigeration cycles, in view of the low efficiency and high technical requirements of the CO compressor and expander, the energy consumption and investment of this process are relatively large, and the start-up and purification of the device take a long time, and the amount of venting during the start-up stage is large

[0004] Chinese invention patent CN 104326472 B "A system and method for producing CO by nitrogen circulation process" adopts nitrogen compression and refrigeration cycle, and the demethanizer and denitrification tower both use conventional evaporators and condensers, and the evaporator uses nitrogen As the heat source, the condenser uses liquid nitrogen as the cold source. This process requires high pressure and large flow of circulating nitrogen gas, which has the disadvantage of high energy consumption. At the same time, the pressure of CO product gas is low.

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