Once-through isothermal methanol-methanation advanced purification process and device

Abstract

The invention discloses a once-through isothermal methanol-methanation advanced purification process which ensures that process gas from gas producing working sections is changed, decarbonized, and compressed by a low-pressure cylinder of a synthesis gas compressor, then enters an isothermal methanol-methanation advanced purification device and is sequentially subject to methanolizing and methanation reactions to obtain the process gas with the content of CO plus CO2 less than 10ppmv, and the process gas is fed into the next working section for drying and purifying. The invention is suitable for a synthesis gas advanced purification process for preparing synthetic ammonia by taking coal, natural gas, acetylene tail gas and coal synthetic tail gas and the like as raw materials, enables thepurified gas to meet the requirements of ammonia synthetic catalysts, has the advantages of high purifying efficiency, strong adaptability, simple flow, less investment, low energy consumption, simpleoperation, no pollution and the like, solves the problems existing in the prior synthetic ammonia and synthetic gas advanced purification process and device and ensures that the content of the CO plus CO2 in the synthesis gas is less than 10ppmv. The invention also provides a device for realizing the once-through isothermal methanol-methanation advanced purification process.

Description

technical field [0001] The invention belongs to the technical field of gas purification and nitrogen fertilizer industry, and in particular relates to a one-pass isothermal deep purification process and device, which is suitable for the syngas depth of synthetic ammonia prepared from coal, natural gas, acetylene tail gas, coal-to-synthetic oil tail gas, etc. In the purification process, the quality of the purified gas meets the requirements of the ammonia synthesis catalyst. Background technique [0002] The ammonia synthesis process is the basis of all nitrogen fertilizer industries and plays a pivotal role in China's agricultural economy. The synthetic ammonia industry is also a high-energy-consuming industry. Even if the synthetic ammonia technology is slightly improved, promotion in the industry will have a positive effect on the energy saving of the entire synthetic ammonia industry. [0003] At present, the feed gas for ammonia synthesis must be pure hydrogen and nitr...

AI Technical Summary

Problems solved by technology

At present, the alcohol alkylation method and alcohol alkylation method used in industry have their own characteristics, but there are also shortcomings. Although it is beneficial to the formation of methanol and methane, CO and CO 2 The gas needs to be compressed to high pressure, which not only increases the power consumption of the compressor, but also increases the risk of leakage; the medium-pressure and high-pressure purification devices are respectively connected to the compressor in series, the process is complicated, and has a great impact on the compressor, especially not suitable for centrifugal Compressor process; medium-pressure and high-pressure purification processes are not suitable for low-pressure ammonia synthesis processes, generally only suitable for small and medium fertilizer plants

The core of the alcohol alkanization method is the use of three processes: fine desulfurization, methanolylation, and methanation. The process gas is connected back and forth between the three processes, and the process is complicated and resistant; the electric furnace tube is used for heating, and the process is complicated; the adiabatic methanolylation reactor is used , cannot by-produce medium-pressure steam, the energy utilization efficiency is low, and a large amount of cooling water is wasted; the single-pass conversion rate is low, and the energy-saving effect is poor; generally only suitable for small and medium-sized fertilizer plants

[0009] Regardless of the alcohol alkylation method or the alcohol alkanization method, because the range of alcohol-ammonia ratio that can be achieved is very large (0.067-1.25 or 0.06-1.3), the output of methanol can account for 6-7% of the total alcohol-ammonia production. 70-80% and can be adjusted, which will inevitably lead to waste of chemical plant production capacity and investment

That is, when more methanol is produced, it will cause waste of ammonia synthesis capacity and low-load and low-efficiency operation; when more synthetic ammonia is produced, it will cause waste of capacity and low-load and low-efficiency operation of the methanol plant

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