Synthesis ammonia and methanol co-production method and device for improving methanol productivity

Abstract

The invention relates to the technical field of synthesis ammonia and methanol co-production process and device, in particular to a synthesis ammonia and methanol co-production method and device for improving methanol productivity, the method introduces a stream of process gas subjected to a shift reaction, and the process gas is added into an inlet of a shift section non-shift gas system to form non-shift mixed gas with low nitrogen content as raw material gas for methanol synthesis. According to the method, the unconverted gas is subjected to a front hydrogen distribution mode, the rear hydrogen distribution amount is remarkably reduced, the nitrogen content in the front hydrogen distribution gas is low, so that the nitrogen content in the methanol synthesis raw material gas is reduced, the nitrogen content in the methanol synthesis circulating gas can be reduced, the emptying amount of the methanol synthesis purge gas is reduced, and the methanol yield is improved; meanwhile, the load of the shift gas washing tower at the low-temperature methanol washing section can be reduced, and the shift gas washing tower stably runs.

Description

technical field [0001] The invention relates to the technical field of synthetic ammonia and co-production of methanol technology and devices, and relates to a method and device for synthesizing ammonia and co-production of methanol for increasing methanol production capacity. Background technique [0002] In the existing co-alcohol process, unshifted gas is used to produce methanol, that is, there is no shift furnace in the methanol synthesis gas system. After the saturated water gas produced by gasification is cooled to separate saturated water, it is washed from the shift gas in the low-temperature methanol washing section of the ammonia synthesis system. The tower is equipped with a stream of hydrogen (i.e. post-allocation hydrogen) to meet the requirements of methanol production, so the load of the shift gas scrubber in the low-temperature methanol washing section is relatively high. When the load of the shift gas scrubber rises to 117% of the load, the operation is unst...

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Problems solved by technology

[0002] In the existing co-alcohol process, unshifted gas is used to produce methanol, that is, there is no shift furnace in the methanol synthesis gas system. After the saturated water gas produced by gasification is cooled to separate saturated water, it is washed from the shift gas in the low-temperature methanol washing section of the ammonia synthesis system. The tower is equipped with a stream of hydrogen (i.e. post-allocation of hydrogen) to meet the requirements of methanol production. In this way, the load of the shift gas scrubber in the low-temperature methanol washing section is relatively high. When the load of the shift gas scrubber rises to 117% of the load, the operation is unstable

In addition, the high-nitrogen tail gas (containing 30% nitrogen) sent out by liquid nitrogen washing is recovered to the inlet of the second conversion furnace after the compressor increases the pressure, so that 2% of the nitrogen in the after-mixed hydrogen enters the methanol synthesis system, and the nitrogen does not participate. Methanol synthesis reaction, due to the presence of nitrogen in the methanol synthesis cycle gas, a large amount of purge gas is emptied, which cannot be recycled, reducing methanol production capacity

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