Method for preparing semi-water gas with fixed bed

Abstract

The invention relates to a method for preparing semi-water gas with a fixed bed. The method comprises the following steps that: 1) about 250 DEG C of semi-water gas passes through a sensible heat recovery device and is cooled to 170 DEG C; 2) then the obtained semi-water gas enters an upper tower of a stripper, 50 DEG C of hot water is sprayed downwards from the top of the upper tower to perform counter-current contact with the semi-water gas, and the semi-water gas is cooled from about 170 DEG C to 70 DEG C; 3) the obtained semi-water gas enters a gas-making cooling tower from the upper tower of the stripper, is cooled to the room temperature and is sent to a gas holder; and 4) the temperature of hot water in the upper tower is increased to 85-90 DEG C, hot water enters a lower tower to perform counter-current contact with room-temperature air from a gas-making fan, the air is humidified and contains rich steam, the temperature is increased to about 75-80 DEG C, and the obtained air is sent to each gas gas-making furnace to prepare semi-water gas. By adopting the method, 200-250kg of steam (which amounts to 40kg of bituminous coal) can be saved per ton of ammonia, 200-250kg of gas-making wastewater can be reduced per ton of ammonia and 30 tons of circulated cooling water can be reduced per ton of ammonia. The method plays an important role in the realization of wastewater zero emission of the synthetic ammonia enterprise.

Description

technical field [0001] The invention relates to a method for producing semi-water gas in a fixed bed in the field of chemical industry. Background technique [0002] The existing fixed-bed semi-water gas synthesis ammonia enterprise adopts sensible heat recovery device to recover part of the sensible heat in the semi-water gas, and the semi-water gas is reduced from 250°C to 140°C. However, because a large amount of pulverized coal in the gas adheres to the heat transfer tube wall of the sensible heat recovery device, the heat transfer efficiency is greatly reduced. The temperature of the sensible heat recovery device often reaches 170 ° C, and then enters the cooling tower to cool down to 35°C, which not only wastes the sensible heat in the gas, but more importantly, the phase change heat of water vapor with 170°C in the gas cannot be recycled, and a large amount of cooling water will be consumed to cool down. After the water vapor condenses into water, it often causes the...

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Problems solved by technology

[0003] The object of the present invention is to provide a method for producing semi-water gas in a fixed bed in order to overcome the defects of the prior art that the sensible heat of semi-water gas and the recovery rate of phase change heat are low

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