Energy-saving inter-section high low temperature gradient alcohol-division two-stage alcohol generation method and energy-saving inter-section high low temperature gradient alcohol-division two-stage alcohol generation device

Abstract

The invention discloses an inter-section high low temperature gradient alcohol-division two-stage alcohol generation method which comprises the following steps: respectively reheating fresh synthesis gas and recycle gas, mixing the fresh synthesis gas with the recycle gas, introducing the mixed gas into a first reactor, and enabling part of carbon oxides to react to obtain methyl alcohol; cooling a mixture containing synthesis gas and methyl alcohol steam output from the first reactor, guiding the mixture to flow to a first methyl alcohol separator, separating out methyl alcohol, pressurizing the separated gas, preheating, then introducing into a second reactor, and enabling part of carbon oxides to react to obtain methyl alcohol; cooling a mixture containing synthesis gas and methyl alcohol steam output from the second reactor, guiding the mixture to flow to a second methyl alcohol separator, separating out methyl alcohol, preheating the separated gas which separately serves as the recycle gas and fresh synthesis gas, mixing the recycle gas and the fresh synthesis gas, and feeding the mixture into the first reactor so as to perform next round of circulating preparation of methyl alcohol. The invention further discloses an inter-section high low temperature gradient alcohol-division two-stage alcohol generation device. The method is relatively high in single-pass alcohol net value and relatively small in circulation ratio, achieves a ton-alcohol steam yield as high as 1.2-1.3 ton, and is high in energy heat recovery amount.

Description

technical field [0001] The invention relates to a large-scale methanol preparation method, in particular to an energy-saving two-stage alcohol production method and device with high and low temperature gradient alcohol separation between stages. Background technique [0002] At present, in large-scale methanol synthesis units, the process for preparing methanol from synthesis gas is mostly a series of towers or a parallel tower process. The main typical technical process is the two-stage isothermal methanol synthesis of "air-cooled reactor + water-cooled reactor" by Lurgi Company in Germany Technology, IMC methanol synthesis technology in Casale, Switzerland (two-stage reaction in the reactor), Davy (ICI) radial flow steam ascending methanol synthesis technology (serial loop series tower process), Denmark The company adopts several shell-and-tube synthesis reactors connected in series and parallel. [0003] With the expansion of production capacity, enterprises pay more at...

AI Technical Summary

Problems solved by technology

Main disadvantages: low heat recovery efficiency and high system consumption when operating under design conditions (low load conditions and late stage of reaction)

The main disadvantages: the operating temperature of the catalyst bed in the upper part of the reactor is relatively high, generally above 280 °C, and the utilization rate of the catalyst in the lower part of the air-cooled part is poor

Main features: The fresh gas is sent into the front and rear systems in two streams, the hydrogen-carbon ratio of the raw material gas entering the reactor in the front and rear systems can be adjusted flexibly, and the hydrogen-carbon ratio and alcohol output of the front and rear systems are approximately equal; the main disadvantage: fresh The gas is directly added to the inlet of the circulator, and the pressure loss is large

Circulating cooling water consumption is large, and the total alcohol net value of the synthesis circuit is low, about 8-9%

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