A low-pressure ammonia synthesis process for co-production of methanol

Abstract

The invention provides a low-pressure ammonia synthesis process for the co-production of methanol, comprising the following steps: 1) performing cryogenic air separation on air to obtain nitrogen and oxygen, and performing pure oxygen autothermal conversion of oxygen and natural gas to obtain CO and H 2 The mixed gas; 2) will contain CO and H 2 The mixed gas is divided into two streams, one stream is used to synthesize methanol under the action of a catalyst, and the other stream is electrolyzed to separate water to obtain hydrogen; 3) hydrogen and nitrogen are mixed to form raw material gas for ammonia synthesis, and the feedstock gas is mixed with iron-based catalyst Carry out primary ammonia synthesis in the first ammonia synthesis tower, synthesis pressure is 5-7MPa; 4) the mixed gas that comes out from described first ammonia synthesis tower enters the second ammonia synthesis tower of filling ruthenium-based catalyst to carry out secondary ammonia synthesis Synthesis, the synthesis pressure is 4‑6MPa. The invention satisfies the requirements of the ammonia synthesis process, ensures the smooth operation of the process, improves the net ammonia value at the outlet of the ammonia synthesis tower and the utilization rate of nitrogen and hydrogen, and co-produces methanol.

Description

technical field [0001] The invention belongs to the technical field of ammonia synthesis, and in particular relates to a low-pressure ammonia synthesis process for co-producing methanol. Background technique [0002] Ammonia is one of the important inorganic chemical products and occupies an important position in the national economy. Except that liquid ammonia can be directly used as fertilizer, nitrogen fertilizers used in agriculture, such as urea, ammonium nitrate, ammonium phosphate, ammonium chloride and various nitrogen-containing compound fertilizers, all use ammonia as raw material. Therefore, synthetic ammonia plays an important role in the national economy. The world's annual synthetic ammonia output has reached more than 100 million tons, of which about 80% of ammonia is used to produce chemical fertilizers, and 20% is used as raw materials for other chemical products. [0003] As we all know, synthetic ammonia is directly synthesized by nitrogen and hydrogen un...

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Problems solved by technology

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the defects in the prior art that the outlet ammonia net value is not high and the utilization rate of nitrogen and hydrogen is low, and then provide a high outlet ammonia net value, high nitrogen and hydrogen utilization rate, and low energy consumption. Low-pressure ammonia synthesis process with low energy consumption and stable operation

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