Sulfur-tolerant shift method and sulfur-tolerant shift device for hydrogen production from coal and ammonia synthesis

Abstract

The invention belongs to the field of coal chemical industry, and discloses a sulfur-tolerant shift method and a sulfur-tolerant shift device for hydrogen production from coal and ammonia synthesis. According to the method, all or part of self-produced steam is used for distributing steam to primarily adjust a water-gas ratio; raw material gas is divided into three paths after the raw material gaspasses through a protection bed reactor, and the water-gas ratio is subjected to tertiary adjustment by adjusting the proportion of the three paths; and the water-gas ratios of a second-stage sulfur-tolerant shift reactor and a third-stage sulfur-tolerant shift reactor are adjusted through a cooling tower, so that the water-gas ratio is subjected to multi-stage adjustment. According to the invention, with the method and the device, by cooperatively sleecting the axial and radial secondary and tertiary sulfur-tolerant shift reactors, arranging the regulating valves on the shell pass and the tube pass of a raw material gas heat exchanger and using other measures, on the premise of the maintaining of the stable operation of the device, the steam consumption is reduced, the inlet temperatureof the first-stage sulfur-tolerant shift reactor is well adjusted, and the service life of the catalyst is well ensured.

Description

technical field [0001] The invention belongs to the field of coal chemical industry, and more specifically relates to a sulfur-resistant conversion method and device for coal-to-hydrogen and synthetic ammonia. Background technique [0002] The sulfur-resistant shift device is an important link in the coal chemical process. Its main function is to transform the CO component and water vapor in the raw gas obtained from coal gasification on the catalyst to produce hydrogen and carbon dioxide, and to increase the H 2 concentration to obtain syngas that meets the requirements. [0003] Since the shift reaction of CO is a strong exothermic reaction, and Al 2 o 3 The supported Co-Mo-based catalyst has high activity, so the catalyst is easily deactivated due to "flying temperature" during the CO shift reaction (especially the first-order shift), and the Al 2 o 3 The carrier is easily agglomerated and inactivated due to hydration reaction with water vapor. Therefore, how to carr...

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Problems solved by technology

Another method is to add a pre-reactor before the main conversion reactor, introduce all the gasification process gas into the pre-reactor, reduce the dry basis composition of CO to about 40%-50% at high space velocity, and then enter the main conversion Reactor, the problem is that the pre-shift reaction product needs to cool down before entering the main reactor, otherwise the main reactor will still be overheated; since all the gas passes through the pre-shift reactor, the heat transfer area needs to be large enough

There is also a method that the first shift reactor adopts a very low water-gas ratio (such as 0.2-0.4), and the degree of reaction is limited by the consumption of water, thereby controlling the bed temperature; but there is a methanation reaction under the low water-gas ratio However, the methanation reaction is a strong exothermic reaction. Once the methanation reaction occurs, the reactor bed will "overheat", causing catalyst sintering and even damage to the reactor; more importantly, most of the gasification process gas The water-air ratio itself is higher than 0.2-0.4, and the low water-air ratio process has multiple cooling and heating processes of the material, resulting in high energy consumption and large equipment investment.

[0005] For the gasification synthesis gas with low water-gas ratio and high CO content, the existing sulfur-tolerant shift device increases the water-gas ratio to above 1.1 by adding a large amount of steam at one time, so as to avoid the temperature rise of the sulfur-tolerant shift reactor. This method will consume a large amount of steam and high energy consumption, but it cannot adjust the inlet temperature of the sulfur-tolerant shift reactor in time, and the delay phenomenon is very obvious. The catalyst is always in a high water-gas ratio, hot spot and high temperature area, which affects the life of the catalyst. Operation fluctuates, making it difficult to achieve smooth operation

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