Nitrogen-cycled methane washing system and method for separating CO and H2 in deep cooling manner

Abstract

The invention discloses a nitrogen-cycled methane washing system for separating CO and H2 in a deep cooling manner. The nitrogen-cycled methane washing system comprises a main heat exchanger, a methane washing tower, a hydrogen gas extraction tower, a demethanation tower, a denitrification tower, a condensation evaporator, a methane liquid pump, a cycled-nitrogen compressor and a CO product compressor. The invention further discloses a nitrogen-cycled methane washing method for separating the CO and H2 in the deep cooling manner. The method comprises the steps of heat exchange, methane washing, dehydrogenation, demethanation, denitrification, nitrogen gas compression and refrigeration cycle, CO product compression and the like. The nitrogen-cycled methane washing system and method have the beneficial effects that the methane washing method is adopted to produce the H2, the energy consumption and investment for producing the H2 are greatly lowered, and the recycling rate of the CO and the H2 can also be increased; the nitrogen cycle compression and refrigeration process is adopted, and high efficiency and low investment of a nitrogen compressor are fully played; the condensation evaporator is arranged, the demethanation tower and the denitrification tower are integrally connected ingeniously, and rectification energy consumption is greatly lowered; the start and purification time of a device can also be shortened, and the venting amount in the start stage is reduced; and good economic benefits and environmentally-friendly benefits are achieved.

Description

technical field [0001] The invention relates to the field of cryogenic gas separation, in particular to a cryogenic separation of CO and H 2 A nitrogen cycle methane scrubbing system and method. 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 coal pressurized gasification, natural gas / naphtha steam reforming or coke oven gas. In addition to CO, H 2 In addition, it also contains a small amount of methane, nitrogen and argon. In view of the high purity requirements of raw material CO (≥98.5%) in the production of chemical products such as ethylene glycol, acetic acid and dimethyl diamide, it is necessary to convert the synthesis gas The removal of hydrogen, methane, nitrogen and argon in the process. Cryogenic separation technology has mature technology, stable operation, large processing capacity, high product purit...

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Problems solved by technology

[0004] Chinese Invention Patent Grant No. CN 101680713 B "Method for Separating Mixtures Containing Carbon Monoxide, Methane, Hydrogen and Optional Nitrogen by Low-Temperature Distillation" and US Patent US 6578377 B1'Recovery of hydrogen and carbon monoxide from mixtures including methane and hydrocarbons heavier thanmethane' 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. At the same time, the purity of the circulating refrigerant CO causes the device to start, The purification time is long, and the venting volume in the start-up stage is large

[0005] Chinese Invention Patent Application No. CN 201510014944.9 "A Method and Device for Efficiently Separating Synthesis Gas to Produce Hydrogen and Carbon Monoxide". The device uses liquid nitrogen as a cold source. This process requires high pressure and large flow rate of circulating nitrogen, which has the disadvantage of high energy consumption, and the pressure of CO products is low.

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