A method and device for drying and purifying ammonia synthesis fresh gas

Abstract

The invention discloses a method for drying and purifying fresh gas from ammonia synthesis. The synthesis gas from a compressor is sent to a cooling step to be cooled to 30-40°C, and the cooled synthesis gas and a small amount of liquid ammonia are sent to a cooling capacity recovery step. Cool to 10°C ~ -30°C, and then send it to a combined purifier for purification. During the purification process of the combined purifier, the synthesis gas enters from the top of the combined purifier, and the liquid ammonia entering from the middle of the combined purifier A countercurrent is formed. After sufficient gas-liquid mixing, the H2O and CO2 contained in the synthesis gas are absorbed and removed by liquid ammonia. The purified synthesis gas is discharged from the upper part of the combined purifier and returned to the cooling recovery step for reheating. The final synthesis gas is sent to the compressor to increase the pressure and then sent to the synthesis circuit. The purification degree of synthesis gas reaches H2O≤0.1ppmv, and CO2 cannot be detected, which meets the purification requirements of ammonia synthesis catalyst for poisons. The quality of liquid ammonia, a product of the synthetic circuit, has reached the national standard premium grade. The invention also discloses a device for realizing the drying and purifying method.

Description

technical field [0001] The present invention relates to the field of purification of ammonia synthesis gas, in particular to a method and device for drying and purifying fresh gas from ammonia synthesis. Through the drying and purification method and purification device, the compressed syngas can be optimized for direct feeding into the catalytic reaction after boosting the pressure. The ammonia synthesis process of the device. Background technique [0002] At present, the process of the ammonia synthesis loop is mainly the ammonia separation process before the tower and the ammonia separation process after the tower. The basic process of separating ammonia after the tower is that the fresh synthesis gas is compressed and boosted by the low-pressure cylinder of the compressor, dried and purified, and then sent to the high-pressure cylinder of the compressor to be compressed and boosted, and then mixed with the circulating gas, further boosted and sent directly to the Ammoni...

AI Technical Summary

Problems solved by technology

However, there are disadvantages in this patent: the resistance drop of the plate tower or the bubble cap tower is large, and the compression power consumption is increased; the equipment investment is large; the scrubbed synthesis gas contains a lot of vaporized ammonia, and this part of the vaporized ammonia enters the synthesis circuit and synthesis tower circulation, reduce the performance of the synthesis tower, increase the circulation gas volume, and then increase the consumption of ammonia synthesis

Although the efficiency of the second stage of the compressor has been improved, it is generally uneconomical due to the increase in cooling capacity usage, power consumption of the compressor and investment in the refrigeration system; and an ammonia cooler must be installed

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