Method and device for multi-stage adjustment of water-gas ratio for sulfur-resistant transformation

Abstract

The invention belongs to the field of coal chemical industry, and discloses a sulfur-resistant conversion method and device for multi-stage adjustment of water-gas ratio. In this method, all or part of the self-produced steam is used for steam distribution to initially adjust the water-gas ratio, and then the raw material gas is heated up after heat exchange and mixed with the sprayed boiler feed water through the spray desuperheater to achieve the second water-gas ratio adjustment. Then the raw material gas is divided into three paths after passing through the guard bed reactor, and the water-gas ratio is adjusted for the third time by adjusting the ratio of the three paths, and then the water-gas ratio of the second and third-stage sulfur-tolerant shift reactors is adjusted through the desuperheating tower. On the premise of maintaining stable operation of the device, the water-gas ratio is adjusted in stages, the consumption of steam is reduced, the inlet temperature of the primary sulfur-tolerant shift reactor is better regulated, and the service life of the catalyst is better guaranteed.

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 multi-stage adjustment of water-gas ratio. 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 c...

AI Technical Summary

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

Images