阅读说明：本技术 煤气化系统的联合除渣装置及其应用方法 (Combined deslagging device of coal gasification system and application method thereof ) 是由 曾令艳 郑智巍 陈智超 李争起 于 2020-07-27 设计创作，主要内容包括：煤气化系统的联合除渣装置及其应用方法,本发明要解决现有气流床气化炉运行温度低时,在余热锅炉内灰渣流动性变差,造成灰渣的沉积而使U形气化炉水平烟道堵塞影响连续运行的问题。本发明煤气化系统的联合除渣装置中余热锅炉下渣口位于余热锅炉底部,气化炉下渣口位于气化炉的底部,竖直下降管的一端与气化炉下渣口相通,竖直下降管的另一端与联合集渣系统中的渣池相连通,倾斜下降管的一端与余热锅炉下渣口相通,倾斜下降管的另一端与竖直下降管相连通。本发明在余热锅炉的底部设有排渣口,使余热锅炉中的渣直接落下,避免了气化设备因工况变化而出现水平烟道堵塞等情况导致被迫停车,增强了运行的稳定性,并能提高气化效率和合成气品质。(The invention discloses a combined deslagging device of a coal gasification system and an application method thereof, and aims to solve the problem that when the operation temperature of the existing entrained flow gasifier is low, the fluidity of ash in a waste heat boiler is poor, so that the ash is deposited, and the continuous operation is influenced because a horizontal flue of a U-shaped gasifier is blocked. The slag discharging port of the waste heat boiler in the combined slag removing device of the coal gasification system is positioned at the bottom of the waste heat boiler, the slag discharging port of the gasification furnace is positioned at the bottom of the gasification furnace, one end of a vertical downcomer is communicated with the slag discharging port of the gasification furnace, the other end of the vertical downcomer is communicated with a slag pool in the combined slag collecting system, one end of an inclined downcomer is communicated with the slag discharging port of the waste heat boiler, and the other end of the inclined downcomer is communicated with the vertical downcomer. The bottom of the waste heat boiler is provided with the slag discharge port, so that slag in the waste heat boiler directly falls down, forced shutdown of gasification equipment due to the conditions of horizontal flue blockage and the like caused by working condition change is avoided, the running stability is enhanced, and the gasification efficiency and the quality of synthesis gas can be improved.)

1. A combined deslagging device of a coal gasification system is characterized by comprising a gasification furnace (2), a waste heat boiler (1), a horizontal flue (3), a waste heat boiler slag discharging port (5), a gasification furnace slag discharging port (4), a vertical descending pipe (6), an inclined descending pipe (7) and a combined slag collecting system (8), wherein a U-shaped gasification reaction zone is formed between the gasification furnace (2) and the waste heat boiler (1) through the horizontal flue (3), the waste heat boiler slag discharging port (5) is positioned at the bottom of the waste heat boiler (1), the gasification furnace slag discharging port (4) is positioned at the bottom of the gasification furnace (2), one end of the vertical descending pipe (6) is communicated with the gasification furnace slag discharging port (4), the other end of the vertical descending pipe (6) is communicated with a slag pool (9) in the combined slag collecting system (8), one end of the inclined descending pipe (7) is communicated with the waste heat boiler slag discharging port (5), the other end of the inclined downcomer (7) is communicated with the vertical downcomer (6), and the inclined downcomer (7) is arranged obliquely downwards;

the combined slag collecting system (8) comprises a slag pool (9), a slag dragging machine (21), an ash lock hopper (18), a circulating pump (13), a slag crusher (10), a first connecting pipe (17), a second connecting pipe (22), a flushing water tank (14) and a high-pressure nitrogen source (15), wherein a slag outlet of the slag pool (9) is connected with a slag inlet of the ash lock hopper (18) through the first connecting pipe (17), the slag crusher (10) is installed on the first connecting pipe (17), the ash lock hopper (18) is communicated with the slag dragging machine (21) through the second connecting pipe (22), a circulating pipeline is arranged between the slag pool (9) and the ash lock hopper (18), and the circulating pump (13) is arranged on the circulating pipeline;

the flushing water tank (14) is communicated with the ash lock hopper (18) through a flushing pipe, and the high-pressure nitrogen source (15) is communicated with the ash lock hopper (18) through an air pipe.

2. A combined slag removal installation for a coal gasification system according to claim 1, characterized in that the flushing tank (14) is provided with a water inlet pipe (12).

3. A combined slag removal unit for a coal gasification system according to claim 1, wherein the inclined downcomer (7) has an angle of 15 ° to 80 ° with the horizontal plane.

4. A combined slag removal installation for a coal gasification system according to claim 1, characterized in that a slag drop valve (11) is arranged on the first connecting pipe (17) below the slag crusher (10).

5. A combined slag removal installation for a coal gasification system according to claim 1, characterized in that a flushing valve (16) is arranged on the flushing pipe between the flushing water tank (14) and the ash lock hopper (18).

6. The combined slag removal unit for coal gasification systems according to claim 1, characterized in that a ram valve (19) is provided on the gas pipe between the high-pressure nitrogen source (15) and the ash lock hopper (18).

7. The combined slag removal installation for a coal gasification system according to claim 1, characterized in that a slag removal valve (20) is provided on the second connecting pipe (22) between the ash lock hopper (18) and the slag conveyor (21).

8. The method for removing the slag by using the combined slag removing device of the coal gasification system is characterized by comprising the following steps of:

when the gasification furnace (2) operates, coal powder is subjected to gasification reaction in a hearth to generate synthesis gas and liquid slag, a part of the liquid slag is deposited on a water-cooled wall in the gasification furnace (2), falls along the water-cooled wall and enters a slag pool (9) through a gasification furnace slag outlet (4) and a vertical downcomer (6);

the residual liquid slag and the synthesis gas form mixed gas flow, the mixed gas flow enters the waste heat boiler (1) through the horizontal flue (3), the temperature of the mixed gas flow is reduced through the heat absorption of a water-cooled wall in the waste heat boiler (1), and the liquid slag in part of the mixed gas flow falls to a slag discharging port (5) of the waste heat boiler along the water-cooled wall in the waste heat boiler (1) and enters a slag pool (9) along an inclined downcomer (7);

secondly, a circulating pump (13) is arranged between a slag pool (9) and an ash lock hopper (18) in the combined slag collecting system (8) to assist in slag water circulation, a slag crusher (10) is arranged at an outlet of the slag pool (9) to crush blocky slag, the slag falls into the slag pool (9) under the action of gravity, and the circulating pump (13) pumps water at the upper part of the ash lock hopper (18) out and sends the water into the slag pool (9) to accelerate the slag collecting speed of the ash lock hopper (18);

thirdly, after the ash lock hopper (18) finishes slag collection, closing a slag falling valve (11), opening a flushing valve (16) to enable the ash lock hopper (18) to release pressure into a water tank (14), opening a slag discharging valve (20) after the pressure is released to normal pressure, flushing the ash lock hopper (18) by using water in a flushing water tank (14), enabling ash slag to fall into a slag salvaging machine (21) under the action of flushing water, stopping flushing, closing the slag discharging valve (20) and the flushing valve (16), simultaneously supplementing water to the water tank (14), opening a punching valve (19), and punching the ash lock hopper (18) by using high-pressure nitrogen (15) until the pressure of the ash lock hopper is equal to the pressure of a hearth;

and fourthly, after the stamping is finished, opening a slag falling valve (11) and a circulating pump (13) and restarting to collect slag, thereby finishing the slag removal of the coal gasification system.

9. The method for removing the slag by using the combined slag removal device of the coal gasification system according to claim 8, wherein the pulverized coal used in the operation of the gasification furnace (2) is high-ash coal.

10. The method of claim 8, wherein the gasifying agent used in the gasifier is oxygen or a mixture of oxygen and steam.

Technical Field

The invention relates to a coal gasification combined deslagging device and a deslagging method by using the same.

Background

China is a world large country for coal production and consumption, coal accounts for about 60% of the primary energy consumption structure of China, most of the coal is used in a direct combustion mode, and the generated coal-fired pollutants cause serious pollution to the ecological environment. Coal gasification is one of the most important clean coal technologies, and can be used for producing industrial fuel gas, civil fuel gas, chemical synthetic raw material gas, synthetic fuel oil raw material gas, hydrogen fuel cells, synthetic natural gas, rocket fuel and the like. The current major coal gasification technologies include moving bed (fixed bed) gasification, fluidized bed gasification, entrained flow bed gasification and molten bed gasification, wherein the entrained flow bed gasification technology has become the main development direction of coal gasification technology due to the advantages of high gasification intensity, large single-furnace production capacity, wide coal type application range, high carbon conversion rate and the like.

The U-shaped gasification technology is that a horizontal flue is arranged at the bottom of a gasification furnace chamber and the bottom of a waste heat boiler to be connected with each other. The gasification hearth, the horizontal flue and the waste heat boiler form a U-shaped gasification reaction area, the U-shaped gasification can increase the space of gasification reaction, prolong the gasification reaction time and effectively improve the efficiency. However, when the load of the gasification furnace is reduced and the temperature in the waste heat boiler is reduced, the temperature of partial ash in the waste heat boiler is reduced, and the fluidity is poor, so that the partial ash is deposited at the bottom of the waste heat boiler and is difficult to flow back to the gasification furnace, and the horizontal flue is blocked by slagging along with the increase of the ash accumulation height, so that the gasification furnace is stopped, and the stability of the system operation is influenced.

In addition, in the existing dry powder coal gasification technology, because different coal types have great component differences and parameters such as ash melting points are also greatly different, when the difference between the used coal type and the designed coal type is large, the problems of excessive ash content of the synthetic gas, unsmooth slag discharge at a slag outlet of the gasification furnace, slag bonding and blockage of a horizontal flue and the like are likely to occur, so that the gasification furnace is frequently maintained, the workload is increased, and the economic benefit is influenced.

Disclosure of Invention

The invention aims to solve the problems that when the operating temperature of the existing entrained flow gasifier is low, the fluidity of ash in a waste heat boiler is poor, the ash is deposited, the horizontal flue of a U-shaped gasifier is blocked, the continuous operation is influenced, and even safety accidents are caused. And provides a coal gasification combined deslagging device and a deslagging method by using the device.

The combined deslagging device of the coal gasification system comprises a gasification furnace, a waste heat boiler, a horizontal flue, a waste heat boiler slag tap, a gasification furnace slag tap, a vertical downcomer, an inclined downcomer and a combined slag collecting system, wherein a U-shaped gasification reaction zone is formed between the gasification furnace and the waste heat boiler through the horizontal flue, the waste heat boiler slag tap is positioned at the bottom of the waste heat boiler, the gasification furnace slag tap is positioned at the bottom of the gasification furnace, one end of the vertical downcomer is communicated with the gasification furnace slag tap, the other end of the vertical downcomer is communicated with a slag pool in the combined slag collecting system, one end of the inclined downcomer is communicated with the waste heat boiler slag tap, the other end of the inclined downcomer is communicated with the vertical downcomer, and the inclined downcomer is arranged obliquely downwards;

the combined slag collecting system comprises a slag pool, a slag salvaging machine, an ash lock hopper, a circulating pump, a slag crusher, a first connecting pipe, a second connecting pipe, a flushing water tank and a high-pressure nitrogen source, wherein a slag outlet of the slag pool is connected with a slag inlet of the ash lock hopper through the first connecting pipe, the slag crusher is arranged on the first connecting pipe, the ash lock hopper is communicated with the slag salvaging machine through the second connecting pipe, a circulating pipeline is arranged between the slag pool and the ash lock hopper, and the circulating pump is arranged on the circulating pipeline;

the flushing water tank is communicated with the ash lock hopper through a flushing pipe, and the high-pressure nitrogen source is communicated with the ash lock hopper through an air pipe.

The method for removing the slag by using the combined slag removing device of the coal gasification system is realized according to the following steps:

when the gasification furnace operates, coal powder is subjected to gasification reaction in a hearth to generate synthesis gas and liquid slag, and a part of the liquid slag is deposited on a water-cooled wall in the gasification furnace, falls along the water-cooled wall and enters a slag pool through a slag outlet and a vertical downcomer of the gasification furnace;

the residual liquid slag and the synthesis gas form mixed gas flow, the mixed gas flow enters the waste heat boiler through the horizontal flue, the temperature of the mixed gas flow is reduced through the heat absorption of a water-cooled wall in the waste heat boiler, and the liquid slag in part of the mixed gas flow falls to a slag discharging port of the waste heat boiler along the water-cooled wall in the waste heat boiler and enters a slag pool along an inclined descending pipe;

secondly, a circulating pump is arranged between a slag pool and an ash lock hopper in the combined slag collecting system to assist slag water circulation, a slag crusher is arranged at the outlet of the slag pool to crush blocky slag, the slag sinks into the slag pool under the action of gravity, and the circulating pump pumps water at the upper part of the ash lock hopper and sends the water into the slag pool to accelerate the slag collecting speed of the ash lock hopper;

after the ash lock bucket collects the slag, a slag falling valve is closed, a flushing valve is opened to enable the ash lock bucket to release the pressure to a water tank, a slag discharging valve is opened after the pressure is released to normal pressure, the ash lock bucket is flushed by water in a flushing water tank, ash falls into a slag conveyor under the action of the flushing water, flushing is stopped, the slag discharging valve and the flushing valve are closed, water is supplied to the water tank, a stamping valve is opened, and the ash lock bucket is stamped to be equal to the pressure of a hearth by high-pressure nitrogen;

and fourthly, after the stamping is finished, opening a slag falling valve and a circulating pump, and recovering slag again, so that slag removal of the coal gasification system is finished.

The combined deslagging device of the coal gasification system and the application method thereof have the following beneficial effects:

the method can reduce the starting and stopping times of the gasification system and effectively improve the operation stability of the gasification furnace;

in the existing U-shaped gasification technology, mixed gas flow from a gasification furnace passes through a waste heat boiler, and molten slag flows back to the gasification furnace through a horizontal flue after falling down in the waste heat boiler. When the load operation is reduced, the temperature in the waste heat boiler is reduced, and when the temperature is too low, the fluidity of ash slag is poor, and the ash slag is difficult to flow back into the gasification furnace through the horizontal flue, so that the horizontal flue is blocked. The waste heat boiler slag discharging port is arranged, so that slag in the waste heat boiler directly falls down, forced shutdown of gasification equipment due to the fact that a horizontal flue is blocked due to working condition change is avoided, and operation stability is enhanced.

The combined deslagging device of the coal gasification system and the application method thereof can effectively improve the economy;

for example, in patent CN1639306 published by international shell research limited, sensible heat of synthesis gas is recovered by using a waste heat boiler process, and the waste heat boiler deposits ash and slag to block a synthesis gas channel and affect operation stability and an operation period in long-term operation. In actual use, a scheme of one-use one-standby and the like can be adopted to ensure the stable operation of the equipment, and the equipment needs to be shut down and maintained more frequently. Building backup facilities can greatly increase initial capital investment, and frequent shutdown maintenance can also reduce economic benefits. The slag discharging port is arranged below the waste heat boiler, slag catching and discharging capacity is enhanced, meanwhile, the waste heat boiler and the gasification furnace share one set of slag removing facility, and under the condition that basic investment is not changed greatly, the operation period of equipment can be effectively prolonged, and economic benefit is improved.

Thirdly, the adaptability of the coal type is strong;

when high ash content or coal with short slag property is adopted, the amount of slag in the gasification furnace and the waste heat boiler is increased, and the slag discharging difficulty is increased; meanwhile, excessive slag causes a large amount of slag to be gathered, the slag cannot be uniformly heated, the fluidity is poor, and the problems of unsmooth slag discharging, blockage of a horizontal flue and the like are likely to occur. The slag discharging device is provided with the two slag discharging ports, so that the slag discharging amount of a single slag discharging port is reduced, and the risk of slag blockage is reduced. Because the combined deslagging is adopted, the problem of blockage of a horizontal flue can be effectively avoided, the adaptability to high-ash coal and coal with short slag property which is not beneficial to slag tapping is better, and the adaptability to coal types is strong.

Fourthly, the gasification efficiency and the quality of the synthesis gas can be improved;

in the actual work of the gasification equipment, ash and slag are deposited on the bottom of the waste heat boiler and the horizontal flue under the influence of coal types, loads and the like, the accumulation of the ash and slag of the waste heat boiler can cause the secondary gasification space to be reduced, and the gasification efficiency is reduced; ash is entrained in the flushed portion of the syngas stream and can result in increased fly ash content in the final syngas and increased difficulty in post-processing. After the combined deslagging device of the coal gasification system is applied, the problem of slag blockage is solved, so that the gasification efficiency and the quality of the synthesis gas can be improved.

Drawings

FIG. 1 is a schematic structural diagram of a combined deslagging device of a coal gasification system according to the invention.

Detailed Description