Process using synthetic gas and fluidized bed to prepare methanol based on interstage absorption and separation

Abstract

The invention provides a process using synthetic gas and fluidized beds to prepare methanol based on interstage absorption and separation. The process is characterized in that a reaction system comprises a methanol fixed bed pre-reactor and the two-stage or multi-stage serially-connected methanol fluidized bed reactors, the purified synthetic gas with the ratio of CO to H2 being 1:2 after conversion is allowed to enter the first-stage fluidized bed reactor with a cooler tube through the methanol fixed bed pre-reactor, part of CO and H2 has average-temperature methanol synthetic reaction with micro-powder methanol catalyst through the cooler tube under 200-280 DEG C and 3.0-7.0Mpa, a gas-solid separator is used to remove the catalyst of the product gas, and the product gas is cooled by a water cooler and enters a methanol absorption and separation tower; the product gas enters the subsequent-stage methanol fluidized bed reactors with cooler tubes after methanol removing, and the process above is repeated; part of separated tail gas is discharged and part of the separated gas is pressurized and returned to serve as the synthetic gas raw material; methanol-rich absorption liquid on the upper section of the absorption tower is subjected to depressurization and flash evaporation to recycle methanol, and the methanol is used as the absorption agent of the lower section of the tower to absorb the methanol and remove fine powder; the methanol discharged from the bottom of the tower is collected and subjected to impurity removing and enters a rectification system.

Description

1. Technical field [0001] The invention provides a synthetic gas fluidized bed methanol production process based on interstage absorption and separation, which belongs to the field of coal chemical industry. 2. Background technology [0002] Methanol synthesis at medium and low pressure is an advanced technology commonly used in the world at present. According to the form of catalyst reactor, it can be divided into three types: fixed bed, gas-solid fluidized bed and three-phase slurry bed. Since methanol synthesis is a strong exothermic reaction, for fixed-bed reactors, due to the difficulty in heat removal, in order to ensure that the reactor does not overheat locally, the single-pass conversion rate of methanol synthesis is generally not high at present, about 10%-15%. Methanol content is only 3%-4%. In order to solve local over-temperature and achieve isothermal operation, foreign countries have also developed a super-conversion methanol fixed-bed synthesis tower, with a...

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Problems solved by technology

[0007] The purpose of the present invention is to provide a syngas fluidized bed methanol process based on interstage absorption and separation in order to overcome the shortcomings of the existing syngas to methanol technology, and solve the full mixing characteristics of the fluidized bed reactor through the methanol fixed bed pre-reactor The defects of rapid catalyst poisoning and deactivation and short service life are caused. The graded reaction reduces the heat extraction load of the heat extraction pipe of the fluidized bed and increases the effective reaction cross-sectional area of ​​the fluidized bed; It promotes the positive reaction of methanolylation and improves the one-way conversion rate of synthesis gas; the concentration of methanol removal is high, the concentration of impurity removal is high, the energy consumption is low, and the harmless treatment of catalyst powder does not contain secondary harmful wastewater containing heavy metals.

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