阅读说明：本技术 一种用于煤制氢及合成氨的耐硫变换方法及装置 (Sulfur-tolerant shift method and device for coal hydrogen production and ammonia synthesis ) 是由 吴迪 王青川 于 2018-09-12 设计创作，主要内容包括：本发明属于煤化工领域,公开了一种用于煤制氢及合成氨的耐硫变换方法及装置。该方法首先通过使用自产蒸汽全部或部分用于配汽初步调节水气比,然后原料气通过保护床反应器后被分为三路,通过调整三路比例第三次调节水气比,之后通过减温塔调节二级及三级耐硫变换反应器的水气比,多级调节水气比,同时配合选用轴径向二级及三级耐硫变换反应器、在原料气换热器管壳程均设置调节阀等措施,在保持装置平稳操作的前提下,减少了蒸汽的消耗,更好的调控一级耐硫变换反应器入口温度,更好的保证了催化剂的寿命。(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 and ammonia synthesis from coal. The method comprises the steps of firstly, using all or part of self-produced steam for preliminary adjustment of water-gas ratio through steam distribution, then dividing raw material gas into three paths after passing through a protective bed reactor, adjusting the water-gas ratio for the third time by adjusting the proportion of the three paths, then adjusting the water-gas ratio of a second-stage sulfur-tolerant shift reactor and a third-stage sulfur-tolerant shift reactor through a temperature reduction tower, adjusting the water-gas ratio in multiple stages, simultaneously matching and selecting axial and radial second-stage and third-stage sulfur-tolerant shift reactors, arranging adjusting valves on tube shell sides of raw material gas heat exchangers and the like, reducing the consumption of steam on the premise of keeping the stable operation of a device, better adjusting and controlling the inlet temperature of the first-stage sulfur-tolerant.)

1. A sulfur tolerant shift process for coal to produce hydrogen and to synthesize ammonia, comprising:

a. raw material gas from a coal hydrogen production and ammonia synthesis device is subjected to liquid separation through a raw material gas liquid separation tank, gas obtained from the top of the raw material gas liquid separation tank is mixed with steam through a gas distribution mixer, water-gas ratio adjustment is carried out, and then the raw material gas enters a raw material gas heat exchanger to exchange heat with reaction gas from the outlet of a first-stage sulfur-tolerant shift reactor;

b. the raw material gas after heat exchange enters a protective bed reactor to remove impurities, and the outlet of the protective bed reactor is respectively connected to the top of the first-stage sulfur-tolerant shift reactor, the middle of the first-stage sulfur-tolerant shift reactor and the outlet pipeline of the first-stage sulfur-tolerant shift reactor through three pipelines; the material flow at the outlet of the protective bed reactor enters a first pipeline, and optionally enters a second pipeline and a third pipeline; the reaction gas at the outlet of the first-stage sulfur-tolerant shift reactor enters a raw material gas heat exchanger to exchange heat with the raw material gas and reduce the temperature; adjusting the feed gas entering the secondary sulfur-tolerant shift reactor by adjusting the material flow ratio entering the three pipelines;

c. high-temperature gas from a raw material heat exchanger enters a temperature reduction tower I to be mixed with boiler feed water from a boiler feed water heat exchanger so as to reduce the temperature and humidify, the water-gas ratio is adjusted, and then the high-temperature gas enters a secondary sulfur-tolerant shift reactor;

d. the reaction gas at the outlet of the second-stage sulfur-tolerant shift reactor passes through a steam generator to generate steam, then enters a temperature reduction tower II to be mixed with boiler feed water from a boiler feed water heat exchanger to reduce the temperature and humidify, and then enters a third-stage sulfur-tolerant shift reactor after water-gas ratio adjustment is carried out;

e. and the reaction gas at the outlet of the three-stage sulfur-tolerant shift reactor sequentially passes through the boiler feed water heat exchanger, the demineralized water heat exchanger, the water cooler and the gas-liquid separator, and the gas obtained at the top of the gas-liquid separator is sent to a downstream device.

2. The sulfur tolerant shift conversion process of claim 1, wherein boiler feed water passes through the boiler feed water heat exchanger and enters the steam generator, the attemperation tower i and the attemperation tower ii, respectively; and all or part of the steam at the outlet of the steam generator is distributed into the feed gas through the steam distribution mixer.

3. The sulfur tolerant shift conversion process according to claim 1, wherein the feed gas has a dry CO content of 40 mol% to 70 mol%, a water-to-gas ratio of 0.3 to 1.2, and a temperature of 180 ℃ to 230 ℃.

4. The sulfur-tolerant shift conversion method according to claim 1, wherein the water-gas ratio of the outlet stream of the steam distribution mixer is 0.2-0.4, the outlet temperature of the raw gas side of the raw gas heat exchanger is 200-260 ℃, the outlet temperature of the temperature reduction tower I is 210-250 ℃, the water-gas ratio is 0.25-0.4, the outlet temperature of the temperature reduction tower II is 210-250 ℃, the water-gas ratio is 0.2-0.35, and the temperature of the boiler feed water from the boiler feed water heat exchanger is 180-250 ℃.

5. The sulfur tolerant shift process of claim 1, wherein the stream entering the first pipeline comprises 60-100% of the stream exiting the guard bed reactor.

6. The sulfur tolerant shift conversion process of claim 1, wherein the second pipeline stream is fed into the primary sulfur tolerant shift reactor at start-up or at a plant load of less than 50%, and the stream entering the second pipeline accounts for 0-40% of the guard bed reactor outlet stream.

7. The sulfur tolerant shift process of claim 1, wherein the third pipeline stream is mixed with the first sulfur tolerant shift reactor outlet stream when the second sulfur tolerant shift reactor inlet CO dry basis concentration is less than 8 mol%, and the third pipeline stream comprises 0-20% of the guard bed reactor outlet stream.

8. A sulfur tolerant shift unit for coal to produce hydrogen and synthetic ammonia, comprising:

the system comprises a raw material gas liquid separating tank, a gas distribution mixer, a raw material gas heat exchanger, a guard bed reactor, a primary sulfur-tolerant shift reactor, a raw material gas heat exchanger, a temperature reduction tower I, a secondary sulfur-tolerant shift reactor, a steam generator, a temperature reduction tower II, a tertiary sulfur-tolerant shift reactor, a boiler feed water heat exchanger, a desalted water heat exchanger, a water cooler and a gas-liquid separator which are sequentially connected according to the material flowing direction;

a boiler water supply pipeline is connected with a boiler water supply heat exchanger, and a boiler water supply outlet of the boiler water supply heat exchanger is respectively connected with a steam generator, a temperature reduction tower I and a temperature reduction tower II; the steam outlet of the steam generator is respectively connected with the steam distribution mixer and the steam pipeline;

wherein, the shell side of the raw gas heat exchanger is provided with a regulating valve;

the bottom of the protective bed reactor is respectively connected with the top, the middle and the bottom of the first-stage sulfur-tolerant shift reactor through a first branch pipeline, a second branch pipeline and a third branch pipeline, and the second branch pipeline and the third branch pipeline are respectively provided with a regulating valve.

9. The sulfur tolerant shift conversion unit of claim 8, wherein a plurality of catalyst beds are arranged in the primary sulfur tolerant shift conversion reactor, wherein the height of the first catalyst bed from top to bottom accounts for 10-90% of the total height of the catalyst beds, and the connection position of the second branch line and the middle part of the primary sulfur tolerant shift conversion reactor is positioned between the catalyst beds.

10. The sulfur tolerant shift unit of claim 8, wherein the secondary and tertiary sulfur tolerant shift reactors are axial and radial reactors.

Technical Field

The invention belongs to the field of coal chemical industry, and particularly relates to a sulfur-tolerant shift method and a sulfur-tolerant shift device for hydrogen production and ammonia synthesis from coal.

Background

Sulfur-tolerant shift device is coal chemical industry processAn important link in the process mainly plays a role in carrying out conversion reaction on CO components in raw material gas obtained by coal gasification and the like and steam on a catalyst to produce hydrogen and carbon dioxide and improve H₂And (4) concentration to obtain the synthesis gas meeting the requirement.

Since the CO shift reaction is strongly exothermic, Al is used₂O₃The supported Co-Mo based catalyst has high activity, so that the catalyst is easily deactivated by 'runaway' during CO shift reaction (especially first-order shift), and Al₂O₃The carrier is easy to agglomerate and deactivate due to hydration reaction with water vapor. Therefore, how to perform sulfur-tolerant CO conversion on a raw material gas with high CO concentration, low water-gas ratio and containing oil stain and dust becomes a technical problem to be solved urgently at present.

At present, three main approaches for solving the problem of CO transformation exist: one method is to reduce the temperature of the bed layer by adopting high water-gas ratio, for example, the temperature of the lower part of the bed layer can be reduced to be lower than 460 ℃ by increasing the water-gas ratio to about 1.8; but has a problem of large steam consumption. The other method is that a pre-reactor is added before a main shift reactor, gasification process gas is completely introduced into the pre-reactor, the composition of CO dry basis is reduced to about 40-50% at high space velocity, and then the gas enters the main shift reactor, and the problem exists that the pre-shift reaction product can enter the main reactor only after being cooled, otherwise, the main reactor still has overtemperature; since all the gas passes through the pre-shift reactor, the heat exchange area needs to be large enough. Yet another approach is to control the bed temperature by using a very low water-to-gas ratio (e.g., 0.2-0.4) in the first shift reactor to limit the extent of the reaction by water consumption; however, the danger of methanation reaction exists under low water-gas ratio, the methanation reaction is a strong exothermic reaction, once the methanation reaction occurs, the bed layer of the reactor can generate temperature runaway, so that the catalyst is sintered, and even the reactor is damaged; more importantly, the water-gas ratio of most gasification process gas is higher than 0.2-0.4, and the process of cooling and heating materials for many times exists by adopting the low water-gas ratio process, so that the energy consumption is high, and the equipment investment is large.

For gasification synthesis gas with low water-gas ratio and high CO content, the existing sulfur-tolerant shift device increases the water-gas ratio to more than 1.1 by adding a large amount of steam once to avoid the temperature rise of the sulfur-tolerant shift reactor, usually, the method consumes a large amount of steam, has high energy consumption, but cannot adjust the inlet temperature of the sulfur-tolerant shift reactor in time, has obvious delay phenomenon, and has the disadvantages that the catalyst is always in a high water-gas ratio and high heat point temperature region, the service life of the catalyst is influenced, the operation of the device fluctuates, and the stable operation is difficult to realize.

Disclosure of Invention

In order to overcome the defects, the invention provides a method for adjusting the water-gas ratio in multiple stages by utilizing self-produced steam, which achieves the purposes of reducing the consumption of the steam, better regulating and controlling the inlet temperature of a first-stage sulfur-tolerant shift reactor and better ensuring the service life of a catalyst on the premise of better controlling the water-gas ratio of each stage of sulfur-tolerant shift reactor and ensuring the stable operation of a device.

The invention provides a sulfur-tolerant shift method for hydrogen production from coal and ammonia synthesis, which comprises the following steps:

a. raw material gas from a coal hydrogen production and ammonia synthesis device is subjected to liquid separation through a raw material gas liquid separation tank, gas obtained from the top of the raw material gas liquid separation tank is mixed with steam through a gas distribution mixer, water-gas ratio adjustment is carried out, and then the raw material gas enters a raw material gas heat exchanger to exchange heat with reaction gas from the outlet of a first-stage sulfur-tolerant shift reactor;

b. the raw material gas after heat exchange enters a protective bed reactor to remove impurities, and the outlet of the protective bed reactor is respectively connected to the top of the first-stage sulfur-tolerant shift reactor, the middle of the first-stage sulfur-tolerant shift reactor and the outlet pipeline of the first-stage sulfur-tolerant shift reactor through three pipelines; the material flow at the outlet of the protective bed reactor enters a first pipeline, and optionally enters a second pipeline and a third pipeline; the reaction gas at the outlet of the first-stage sulfur-tolerant shift reactor enters a raw material gas heat exchanger to exchange heat with the raw material gas and reduce the temperature; adjusting the water-gas ratio of the feed gas entering the secondary sulfur-tolerant shift reactor by adjusting the material flow ratio entering the three pipelines, and adjusting the outlet temperature of the primary sulfur-tolerant shift reactor;

c. high-temperature gas from a raw material heat exchanger enters a temperature reduction tower I to be mixed with boiler feed water from a boiler feed water heat exchanger so as to reduce the temperature and humidify, the water-gas ratio is adjusted, and then the high-temperature gas enters a secondary sulfur-tolerant shift reactor;

d. the reaction gas at the outlet of the second-stage sulfur-tolerant shift reactor passes through a steam generator to generate steam, then enters a temperature reduction tower II to be mixed with boiler feed water from a boiler feed water heat exchanger to reduce the temperature and humidify, and then enters a third-stage sulfur-tolerant shift reactor after water-gas ratio adjustment is carried out;

e. and the reaction gas at the outlet of the three-stage sulfur-tolerant shift reactor sequentially passes through the boiler feed water heat exchanger, the demineralized water heat exchanger, the water cooler and the gas-liquid separator, and the gas obtained at the top of the gas-liquid separator is sent to a downstream device.

According to the invention, preferably, boiler feed water passes through the boiler feed water heat exchanger and then enters the steam generator, the temperature reduction tower I and the temperature reduction tower II respectively; and all or part of the steam at the outlet of the steam generator is distributed into the feed gas through the steam distribution mixer.

In the invention, the preferable CO dry basis content in the feed gas from the coal hydrogen production and ammonia synthesis device is 40-70 mol%, the water-gas ratio is 0.3-1.2, and the temperature is 180-230 ℃. The raw material gas is firstly subjected to liquid separation through a raw material gas liquid separation tank, gas obtained from the top of the raw material gas liquid separation tank and all or part of steam from a steam generator are mixed through a steam distribution mixer, and the water-gas ratio is adjusted, wherein the water-gas ratio of the outlet material flow of the steam distribution mixer is preferably 0.2-0.4. The raw material gas subjected to preliminary water-gas ratio adjustment enters a raw material gas heat exchanger to exchange heat with reaction gas from the outlet of a first-stage sulfur-tolerant shift reactor, the temperature of the raw material gas after heat exchange is preferably controlled by a tube shell side temperature regulating valve of the raw material gas heat exchanger, and the outlet temperature of the raw material gas side of the raw material gas heat exchanger is preferably controlled to be 200-260 ℃.

The raw material gas after heat exchange enters a protective bed reactor to remove impurities and dust particles and then is divided into three pipelines, the first pipeline is connected with the top of the first-stage sulfur-tolerant shift reactor, and the material flow entering the first pipeline preferably accounts for 60-100% of the material flow at the outlet of the protective bed reactor. The second pipeline is connected with the middle part of the first-stage sulfur-tolerant shift reactor, preferably, when the start-up or the device load is lower than 50%, the material flow of the second pipeline is sent into the first-stage sulfur-tolerant shift reactor, and the material flow entering the second pipeline accounts for 0-40% of the material flow at the outlet of the protective bed reactor. And the third pipeline is connected with an outlet pipeline of the primary sulfur-tolerant shift reactor, preferably, when the CO dry basis concentration at the inlet of the secondary sulfur-tolerant shift reactor is less than 8 mol%, the material flow of the third pipeline is mixed with the material flow at the outlet of the primary sulfur-tolerant shift reactor, and the material flow entering the third pipeline accounts for 0-20% of the material flow at the outlet of the protective bed reactor. And adjusting the water-gas ratio of the feed gas for the third time by adjusting the material flow ratio entering the three pipelines.

And the reaction gas at the outlet of the first-stage sulfur-tolerant shift reactor enters a raw material gas heat exchanger to exchange heat with the raw material gas for cooling, then enters a temperature reduction tower I to be mixed with boiler feed water from a boiler feed water heat exchanger for cooling and humidifying, and enters a second-stage sulfur-tolerant shift reactor after adjusting the water-gas ratio, wherein the outlet temperature of the temperature reduction tower I is preferably 210-250 ℃, and the water-gas ratio is preferably 0.25-0.4.

And the reaction gas at the outlet of the second-stage sulfur-tolerant shift reactor is subjected to steam generation through a steam generator, then enters a temperature reduction tower II, is mixed with boiler feed water from a boiler feed water heat exchanger for cooling and humidifying, is adjusted in water-gas ratio and then enters a third-stage sulfur-tolerant shift reactor, wherein the outlet temperature of the temperature reduction tower II is preferably 210-250 ℃, and the water-gas ratio is preferably 0.2-0.35.

And the reaction gas at the outlet of the three-stage sulfur-tolerant shift reactor sequentially passes through the boiler feed water heat exchanger, the demineralized water heat exchanger, the water cooler and the gas-liquid separator, and the gas obtained at the top of the gas-liquid separator is sent to a downstream device.

The boiler feed water is subjected to heat exchange with reaction gas at the outlet of the three-stage sulfur-tolerant shift reactor through a boiler feed water heat exchanger and then enters a steam generator, a temperature reduction tower I and a temperature reduction tower II respectively, and preferably, the temperature of the boiler feed water from the boiler feed water heat exchanger is 180-250 ℃. And exchanging heat with reaction gas from the outlet of the second-stage sulfur-tolerant shift reactor in a steam generator to obtain 40barg steam, distributing all or part of the steam into the feed gas through a steam distribution mixer, and delivering the rest steam into a steam pipe network when only part of the steam is distributed into the feed gas through the steam distribution mixer.

In another aspect, the present invention provides a sulfur-tolerant shift converter for hydrogen production from coal and ammonia synthesis, comprising:

the system comprises a raw material gas liquid separating tank, a gas distribution mixer, a raw material gas heat exchanger, a guard bed reactor, a primary sulfur-tolerant shift reactor, a raw material gas heat exchanger, a temperature reduction tower I, a secondary sulfur-tolerant shift reactor, a steam generator, a temperature reduction tower II, a tertiary sulfur-tolerant shift reactor, a boiler feed water heat exchanger, a desalted water heat exchanger, a water cooler and a gas-liquid separator which are sequentially connected according to the material flowing direction;

a boiler water supply pipeline is connected with a boiler water supply heat exchanger, and a boiler water supply outlet of the boiler water supply heat exchanger is respectively connected with a steam generator, a temperature reduction tower I and a temperature reduction tower II; the steam outlet of the steam generator is respectively connected with the steam distribution mixer and the steam pipeline;

wherein, the shell side of the raw gas heat exchanger is provided with a regulating valve;

the bottom of the protective bed reactor is respectively connected with the top, the middle and the bottom of the first-stage sulfur-tolerant shift reactor through a first branch pipeline, a second branch pipeline and a third branch pipeline, and the second branch pipeline and the third branch pipeline are respectively provided with a regulating valve.

According to the invention, preferably, a plurality of stages of catalyst beds are arranged in the first stage sulfur-tolerant shift reactor, wherein the height of the first stage catalyst bed arranged from top to bottom accounts for 10-90% of the total height of the catalyst beds, and the joint of the second branch pipeline and the middle part of the first stage sulfur-tolerant shift reactor is positioned between the catalyst beds.

In the invention, no special requirement is required for selection of each device, preferably, the secondary sulfur-tolerant shift reactor and the third-stage sulfur-tolerant shift reactor are axial radial reactors, the steam generator is preferably in a kettle type, a steam outlet is directly connected with an inlet of a steam distribution mixer through a pipeline, a preferred top inlet of the temperature reduction tower I is connected with a feed gas heat exchanger through a pipeline, a preferred side inlet is connected with a boiler feed water preheater through a pipeline, a preferred top inlet of the temperature reduction tower II is connected with the steam generator through a pipeline, and a preferred side inlet is connected with the boiler feed water heat exchanger through a pipeline.

According to the invention, all or part of self-produced steam is used for preliminarily adjusting the water-gas ratio by steam distribution, then the feed gas is divided into three paths after passing through the protective bed reactor, the water-gas ratio is adjusted for the third time by adjusting the proportion of the three paths, then the water-gas ratios of the second-stage and third-stage sulfur-tolerant shift reactors are adjusted by the temperature reduction tower, the water-gas ratios are adjusted in multiple stages, and meanwhile, the measures of selecting the axial-radial second-stage and third-stage sulfur-tolerant shift reactors, arranging adjusting valves on the shell sides of the feed gas heat exchanger and the like are matched, so that on the premise of keeping the stable operation of the device, the consumption of the steam is reduced, the inlet temperature of the first-.

Compared with the prior art, the invention has the following advantages:

(1) the temperature regulating valves are arranged on the shell-and-tube sides of the raw gas heat exchanger, so that the inlet temperature of the first-stage sulfur-tolerant shift reactor can be flexibly adjusted in time to meet different temperature requirements in the initial stage and the final stage, and temperature runaway is prevented.

(2) The invention utilizes the self-produced steam in the device to be fully or partially used for steam distribution, reduces the water-steam ratio, and adjusts the gasified synthetic gas with high CO content to the range which is easy to control the shift reaction, thereby being beneficial to the stable operation of the sulfur-resistant shift device and simultaneously reducing the consumption of extra steam.

(3) The first-stage sulfur-tolerant shift reactor adopts a sectional feeding mode, so that the catalyst bed layer in the first-stage sulfur-tolerant shift reactor is prevented from being in a high-temperature area with heat point during the start-up period and low-load operation, the service life of the catalyst can be effectively ensured, the CO at the inlet of the second-stage sulfur-tolerant shift reactor is ensured to have proper concentration, and the temperature at the outlet is increased enough, so that the heat of the whole device is balanced.

All the advantages enable the invention to have higher economic benefit, lower comprehensive energy consumption and more controllable device operation compared with the traditional technical method. The invention is particularly suitable for the sulfur-resistant shift unit of the coal gasification process.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout.

FIG. 1 shows a schematic diagram of a sulfur tolerant shift process for coal to hydrogen and ammonia synthesis according to one embodiment of the present invention.

Description of reference numerals:

1. a raw material gas liquid separation tank; 2. a gas distribution mixer; 3. raw material gas; 4. a raw gas heat exchanger; 5. protecting the bed reactor; 6. a first stage sulfur tolerant shift reactor; 7. a temperature reduction tower I; 8. a secondary sulfur tolerant shift reactor; 9. a steam generator; 10. a temperature reduction tower II; 11. a three-stage sulfur tolerant shift reactor; 12. a boiler feed water heat exchanger; 13. a demineralized water heat exchanger; 14. a water cooler; 15. a gas-liquid separator; 16. feeding water to the boiler; 17. changing the product gas; 18. and (4) steam.

Detailed Description

Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein.