Dehydrogenation method of carbon dioxide feed gas

Abstract

The invention discloses a dehydrogenation method of carbon dioxide feed gas. The method comprises the following steps: 1) injecting oxygen-enriched air in the carbon dioxide feed gas to ensure the content of oxygen to be 1.25-1.4%; 2) injecting the carbon dioxide feed gas containing oxygen-enriched air into a compression engine to compress, performing fine desulfurization, performing heat transferto the desulphurized gas, heating, sending the obtained gas to a dehydrogenation reactor to dehydrogenize to ensure the content of hydrogen and other combustible gases in the dehydrogenized carbon dioxide gas to be less than 50PPm; 3) performing heat transfer to the dehydrogenized gas, cooling, then sending the obtained gas to a CO2 vapour liquid separator to perform gas water separations and finally emptying liquid drops to obtain the gas which is used for the synthesis of urea. The dehydrogenation method of carbon dioxide feed gas adds oxygen to perform dehydrogenation and adds air to perform anticorrosion so as to avoid the problem that a great deal of nitrogen and other inert gases are generated after the dehydrogenation step, reduce the venting amount of the high pressure system, increase the conversion rate, improve the system loading, increase the urea capacity, reduce the absorption loading, desorption loading and hydrolysis loading, lower the consumption of ammonia, steam andthe like and benefit the environmental control.

Description

technical field [0001] The invention relates to a dehydrogenation method of carbon dioxide raw material gas. Background technique [0002] Currently, CO 2 When the stripping process produces urea, the CO 2 A certain amount of air is added to the inlet of the first or second stage of the compressor. The main purpose is: 1. Use the oxygen in the air to remove the hydrogen in the raw material gas under the action of the catalyst to ensure that the high-pressure scrubber releases the explosive components of the air. Keep it outside the explosive range to ensure system safety; 2. Urea production is a high-temperature, high-pressure, highly corrosive reaction. In order to ensure the long-term operation of urea production equipment, oxygen in the air is used to blunt the inner wall of high-pressure equipment. A dense oxide film is formed to prevent corrosion of high-voltage equipment. [0003] However, there are the following drawbacks: CO 2 The purity of the raw material gas i...

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Problems solved by technology

[0004] In view of the above-mentioned existing situation, in order to solve the problem that the venting volume of the high-pressure system of the urea plant remains high, the present invention provides a dehydrogenation method of carbon dioxide raw material gas. The present invention proposes to add pure oxygen to the dehydrogenation reactor for dehydrogenation Hydrogen, adding air for anticorrosion, to reduce the problem of a large amount of nitrogen and other inert gases after dehydrogenation, reduce the venting volume of the high-pressure system, improve the conversion rate, increase the system load, and at the same time ensure a certain amount of nitrogen storage to ensure system safety

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