Method and device for recycling hydrogen from synthesis ammonia released air and preparing LNG (liquefied natural gas) with membrane separation and cryogenic integration technology

Abstract

The invention discloses a method and a device for recycling hydrogen from synthesis ammonia released air and preparing LNG (liquefied natural gas) with a membrane separation and cryogenic integration technology. The method is characterized in that the synthesis ammonia released air sequentially passes through three treatment units as follows: a synthesis ammonia released air pretreatment unit, a membrane separation and hydrogen recycling unit, and an LNG preparation unit with a cryogenic technology. The integration technology utilizes technical advantages of a membrane technology which is small in investment and high in hydrogen recovery rate and doesn't produce depressurized tail gas and technical advantages of the cryogenic technology which can prepare LNG, and simultaneously avoids technical defects that the cryogenic investment is large, the energy consumption is high, and a single membrane or PSA (Pressure Swing Adsorption) technology cannot simultaneously recycle H2 and CH4. By means of the integration technology, the technical problem that the synthesis ammonia released air cannot be economically, conveniently, efficiently and comprehensively utilized is solved; while the hydrogen is recycled, the LNG can be prepared; and a new energy-saving, emission-reduction and efficient technological process route is provided for a synthesis ammonia enterprise, and the integration technology has an excellent application prospect.

Description

technical field [0001] The invention relates to the field of synthetic ammonia industry, in particular to a method and device for recovering hydrogen from the air released from synthetic ammonia and producing LNG by using membrane separation and cryogenic integration technology. Background technique [0002] At present, ammonia synthesis is a basic chemical industry and occupies an important position in the chemical industry. At present, my country's synthetic ammonia production exceeds 50 million tons per year, accounting for about one-third of global production. With the increase of the global population, the human demand for increased crop production determines the increase in demand for synthetic ammonia. In contrast, since synthetic ammonia is a high-energy-consuming industry, and its raw materials are non-renewable resources such as coal, oil, and natural gas, resources Today, with increasingly tense and more serious environmental pollution, how to improve the energy ...

AI Technical Summary

Problems solved by technology

At present, the usual way to deal with the release air of synthetic ammonia is to use membrane separation or PSA technology to recover only hydrogen, and burn or discharge other gases containing a large amount of methane, which will cause a lot of waste of resources

Due to the characteristics of the technology itself, membrane separation or PSA technology cannot be used alone to recover hydrogen and methane at the same time, and cryogenic technology alone is rarely used due to large equipment investment, high energy consumption, complicated operation, and poor economy.

Therefore, the method and device for simultaneously recovering hydrogen and methane from vented air are seldom mentioned.

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