Method and device for preparing hydrogen and carbon monoxide by efficient synthesis gas separation

Abstract

The invention relates to a method and a device for preparing hydrogen and high-purity carbon monoxide by efficient synthesis gas separation. Continuous rectification is performed by a methane washing tower (C1 tower) with an intermediate heat exchanger and a tower bottom reboiler, a deoxidation-methane tower (C2 tower) with an overhead condenser and a tower pot reboiler and a denitrification tower (C3 tower) with an overhead condenser and a tower pot reboiler to prepare the hydrogen and the high-purity carbon monoxide. According to the method and the device for preparing the hydrogen and the carbon monoxide by efficient synthesis gas separation, the methane washing tower with the reboiler and an intermediate cooler are applied, synthesis gas in which hydrogen content is smaller than 0.5% can be obtained by a single tower pot, hydrogen content of the tower pot is low so that a stripping tower is never required, meanwhile, the hydrogen and the carbon monoxide can be prepared by low energy consumption, 99.9% and over 99.999% of carbon monoxide products can be prepared, and a carbon monoxide compressor is never required when the pressure is larger than 0.2MPa during carbon monoxide preparation so that purposes of saving energy and investments and enhancing operation safety can be achieved.

Description

technical field [0001] The present invention relates to a method for gas separation by cryogenic liquefaction, in particular to a method for separating hydrogen, methane and carbon monoxide from synthesis gas. Background technique [0002] Carbon monoxide is usually separated from synthesis gas produced by steam reforming catalytic conversion or partial oxidation of natural gas, coal and other hydrocarbons. In addition to carbon monoxide, there are often hydrogen, nitrogen, methane and oxygen in the gas. These impurity components often limit the use of carbon monoxide, so that many mixed gases containing a large amount of carbon monoxide can only be burned and emptied, resulting in a waste of resources. [0003] Carbon monoxide and hydrogen are important basic chemical raw materials, widely used in chemical processes such as oxo synthesis, and have become important raw materials for a series of basic organic chemical products and intermediates. The source of carbon monoxid...

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Problems solved by technology

The methane scrubber of this invention does not contain a reboiler, so it cannot be removed in one tower at a time. It is necessary to add a stripper to discharge hydrogen-rich gas at the top of the stripper. This gas cannot be used as a product gas, so the hydrogen extraction rate of the device lower

[0007] In the patent CN101568788B, the raw hydrogen gas enters the bottom of the C1 tower, and a C2 tower is required to remove the residual hydrogen. The raw materials with a hydrogen content > 1.5% in the C2 tower are removed at the top of the C2 tower. This part of the crude hydrogen cannot be used as a hydrogen product. Reduced hydrogen recovery

At the same time, in this patent, the decompressed carbon monoxide 29 enters the condensing evaporator of the C4 tower and evaporates into gas, then enters the main heat exchanger for reheating, enters the circulating compressor for boosting, and then outputs, and the carbon monoxide compressor has a safety function during operation risks of

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