阅读说明：本技术 一种带有喷淋降温装置的u形煤气化余热锅炉及降温方法 (U-shaped coal gasification waste heat boiler with spraying cooling device and cooling method ) 是由 曾令艳 谭紫莹 路跃 陈智超 李争起 于 2020-11-03 设计创作，主要内容包括：一种带有喷淋降温装置的U形煤气化余热锅炉及降温方法,本发明涉及一种U形煤气化余热锅炉,本发明是要解决现有煤气化系统二次气化室内熔渣易附着在水冷壁上,形成大的渣块,渣块掉落时堵塞水平烟道,影响气化炉安全运行；同时现有煤气化系统余热换热室入口合成气温度高导致余热换热室内受热面烧损和排烟温度高的问题,气化炉体与二次气化室连通,气化炉出渣口设置在渣池内,余热换热室靠近二次气化室设置,气化炉体与二次气化室通过水平烟道连通,余热换热室内设置有对流受热面,对流受热面底部为合成气出口,对流受热面顶部设有合成气入口,喷淋系统安装在二次气化室水冷壁的外侧壁上,喷淋系统、供水系统均与控制系统连接。本发明属于锅炉领域。(The invention relates to a U-shaped coal gasification waste heat boiler with a spray cooling device and a cooling method, and aims to solve the problems that molten slag in a secondary gasification chamber of an existing coal gasification system is easy to attach to a water-cooled wall to form a large slag block, and the horizontal flue is blocked when the slag block falls off to influence the safe operation of a gasification furnace; meanwhile, the problem that the temperature of synthesis gas at the inlet of the waste heat exchange chamber of the existing coal gasification system is high, so that the heating surface in the waste heat exchange chamber is burnt and the exhaust gas temperature is high is solved. The invention belongs to the field of boilers.)

1. A U-shaped coal gasification waste heat boiler with a spray cooling device comprises a waste heat boiler body (1), a gasification furnace body (7), a horizontal flue (10), a gasification furnace slag hole (12) and a slag pool (13); the waste heat boiler body (1) comprises a secondary gasification chamber (2) and a waste heat exchange chamber (21), and is characterized in that: the secondary gasification chamber (2) comprises a spraying system, a water supply system and a control system; the gasification furnace body (7) is communicated with the secondary gasification chamber (2), the gasification furnace slag outlet (12) is arranged in a slag pool (13), the waste heat exchange chamber (21) is arranged close to the secondary gasification chamber (2), the gasification furnace body (7) is communicated with the secondary gasification chamber (2) through a horizontal flue (10), a convection heating surface (16) is arranged in the waste heat exchange chamber (21), the bottom of the convection heating surface (16) is a synthetic gas outlet (14), the top of the convection heating surface (16) is provided with a synthetic gas inlet (20), the spraying system is arranged on the outer side wall of the water-cooled wall of the secondary gasification chamber (2), the water supply system is communicated with the spraying system, and the spraying system and the water supply system are both connected with the control system.

2. The U-shaped coal gasification waste heat boiler with the spray cooling device according to claim 1, characterized in that: the spraying system comprises a plurality of connecting flanges (3), a plurality of supports (17), a plurality of nozzles (18) and a plurality of spray pipes (19), one connecting flange (3) is installed at each of two ends of each spray pipe (19), the plurality of spray pipes (19) are installed on the secondary gasification chamber (2) from top to bottom, the plurality of nozzles (18) are installed on the spray pipes (19) along the peripheral direction, and the spray pipes (19) are installed on the outer wall of the water wall of the secondary gasification chamber (2) through the plurality of supports (17).

3. The U-shaped coal gasification waste heat boiler with the spray cooling device according to claim 2, characterized in that: the water supply system comprises a water pump (11), a water inlet pipe (5) and a water outlet pipe (6), the water pump (11) is installed on the water inlet pipe (5), the water inlet pipe (5) is communicated with the inlet end of a spray water pipe (19), and the outlet end of the spray water pipe (19) is communicated with the water outlet pipe (6).

4. The U-shaped coal gasification waste heat boiler with the spray cooling device according to claim 3, characterized in that: control system includes DCS controller (15), flowmeter (4), a plurality of high temperature thermocouple (9), a plurality of medium temperature thermocouple (22) and a plurality of electric valve (8), install one flowmeter (4) and one electric valve (8) on every spray header (19), a plurality of high temperature thermocouple (9) are installed on secondary gasification room (2) water-cooling wall, a plurality of medium temperature thermocouple (22) set up around synthetic gas entry (20), DCS controller (15) and flowmeter (4), high temperature thermocouple (9), water pump (11), medium temperature thermocouple (22) and electric valve (8) are connected.

5. The U-shaped coal gasification waste heat boiler with the spray cooling device according to claim 2, characterized in that: the spray header (19) is a rectangular frame body, the number of the connecting flanges (3) is three, the three spray headers (19) are arranged on the outer side wall of the water wall of the secondary gasification chamber (2) at equal intervals from top to bottom, the distance from the nozzle (18) on the top spray header (19) to the synthesis gas inlet (20) is L1, the distance between every two adjacent spray headers (19) is L2, the distance from the nozzle (18) on the bottom spray header (19) to the bottom of the secondary gasification chamber (2) is L3, the distance from the center lines of the two adjacent nozzles (18) on the frame of each spray header (19) is M, the nozzle jet flow contraction section diameter of the nozzle (18) is a, and the numerical values of M, L1, L2 and L3 are less than or equal to one half of a.

6. The U-shaped coal gasification waste heat boiler with the spray cooling device according to claim 5, characterized in that: the cross section of the secondary gasification chamber (2) is rectangular, the side length of a hearth of the secondary gasification chamber (2) is I, the product of the number of nozzles (18) on each side of the spray header (19) and the diameter value of the jet flow contraction section of the nozzles (18) is more than or equal to the side length I of each hearth of the secondary gasification chamber (2), the nozzle range of the nozzles (18) is b, b is more than or equal to one half of I, the distance between the edge nozzles (18) on the spray header (19) and the edge of the frame of the spray header (19) is N, and N is less than or equal to one half of a.

7. The U-shaped coal gasification waste heat boiler with the spray cooling device according to claim 2, characterized in that: the nozzles (18) are atomizing nozzles, the angle formed by the central line of each nozzle (18) and the horizontal plane is 0-15 degrees, and the nozzles (18) are inclined upwards by 0-15 degrees or downwards by 0-15 degrees.

8. The utilization right of claims 1 to 7 discloses a cooling method of a U-shaped coal gasification waste heat boiler with a spray cooling device, which is characterized in that: the method is realized according to the following steps:

the method comprises the following steps: when spraying is carried out, the DCS controller (15) controls the spray head of the nozzle (18) to be extended, the spray head of the nozzle (18) extends into a hearth of the secondary gasification chamber (2) to spray water for cooling the synthesis gas and the molten slag, and when spraying is finished, the DCS controller (15) controls the spray head of the nozzle (18) to be shortened and quit the hearth of the secondary gasification chamber (2) to avoid the nozzle (18) from being damaged by high temperature;

step two: when the mixed gas flow of the synthesis gas and the liquid slag generated by the gasification furnace enters a secondary gasification chamber (2) in the waste heat boiler (1), one part of slag is attached to the water-cooled wall of the secondary gasification chamber (2), and the other part of slag is changed into fly ash and then flows out from a synthesis gas outlet (14) along with the synthesis gas;

step three: after the mixed gas flow of the synthesis gas and the liquid slag in the secondary gasification chamber (2) is cooled by water spraying, the liquid slag is divided into three parts, a small amount of slag in the first part flows with the synthesis gas in a mixed way and enters a waste heat exchange chamber (21) with the synthesis gas; the second part of slag is solidified into small slag blocks and falls to the bottom of the secondary gasification chamber (2); the third part of slag is adhered to the water wall of the secondary gasification chamber (2), some slag is washed and falls to the bottom, some slag is exploded into small slag blocks after being cooled and falls to the bottom, the small slag blocks falling from the bottom of the secondary gasification chamber (2) are heated by high-temperature synthetic gas coming from the horizontal flue (10) and liquid slag, the small slag blocks are melted to form new slag, the liquid slag from the gasification furnace and the new slag melted by the small slag blocks are mixed, and the mixture returns to the gasification furnace (7) along the inclined horizontal flue (10), flows out from a slag hole (12) of the gasification furnace and enters a slag pool (13).

9. The utilization right of claim 8 discloses a cooling method of a U-shaped coal gasification waste heat boiler with a spray cooling device, which is characterized in that:

in the first step, when a high-temperature thermocouple (9) in a secondary gasification chamber (2) detects that the temperature of synthesis gas is higher than 1300 degrees, or a medium-temperature thermocouple (22) detects that the temperature is higher than 900 degrees, the high-temperature thermocouple (9) or the medium-temperature thermocouple (22) transmits signals to a DSC controller (15), the DCS controller (15) controls a water pump (11) and an electric valve (8) to be opened, spray water enters a water inlet pipe (5), the controller (15) controls a spray head of a nozzle (18) to be extended, the spray head of the nozzle (18) extends into a hearth of the secondary gasification chamber (2) to spray water for cooling, when the high-temperature thermocouple (9) in the secondary gasification chamber (2) detects that the temperature of the synthesis gas is smaller than or equal to 1300 degrees, or the medium-temperature thermocouple (22) detects that the temperature is smaller than or equal to 900 degrees, the high-temperature thermocouple (9) or the medium-temperature thermocouple (22) transmits signals to the DSC controller (15), and the DCS controller, and the secondary gasification chamber (2) hearth is withdrawn, so that the nozzle (18) is prevented from being damaged by high temperature. The water pump (11) and the electric valve (8) are gradually closed, and the residual water flows out from the water outlet pipe (6).

10. The utilization right of claim 8 discloses a cooling method of a U-shaped coal gasification waste heat boiler with a spray cooling device, which is characterized in that:

in the second step, the synthesis gas and a small amount of slag in the secondary gasification chamber (2) enter a waste heat exchange chamber (21) through a synthesis gas inlet (20) at the upper part of the secondary gasification chamber (2), energy is transferred in the waste heat exchange chamber (21) through a convection heating surface, and the slag is converted into fly ash and flows out from a synthesis gas outlet (14) along with the synthesis gas.

Technical Field

The invention relates to a U-shaped coal gasification waste heat boiler, in particular to a U-shaped coal gasification waste heat boiler with a spray cooling device and a cooling method, and belongs to the field of boilers.

Background

Coal is the most abundant conventional energy source and the most widely distributed conventional energy source in the world, and is also an important strategic resource. In the world, the coal reserves account for about 90% of the total reserves of various energy sources, and the coal reserves are widely applied to the industrial production fields of steel, electric power, chemical industry and the like and the living field of residents. With the increase of low-carbon economic development and environmental governance, the environmental pressure of coal as fossil energy is getting bigger and bigger, so that an efficient and clean coal gasification technology is a necessary strategic choice for economic and social sustainable development in China, and is an important basis for ensuring stable and reliable supply of energy and sustainable development in China.

At present, the coal gasification process is operated in China, and is distinguished according to the contact mode of coal materials and a gasification agent in a gasification furnace, and mainly comprises a fixed bed gasification technology, a fluidized bed gasification technology, an entrained flow gasification technology, a molten bed gasification technology and the like. On the basis of adopting an entrained flow coal gasification technology, a U-shaped coal gasification reaction device disclosed in patents CN106987279A and CN107099337A of Harbin university of industry connects a gasification furnace and a waste heat boiler through a horizontal flue to form a U-shaped coal gasification reaction area. The adoption of the U-shaped coal gasification mode has the advantages of increasing the space of gasification reaction, prolonging the gasification reaction time and improving the reaction efficiency. However, the problem of overhigh temperature of the synthesis gas at the inlet of the waste heat exchange chamber also exists, so that the burning loss of the heating surface in the waste heat exchange chamber is caused, slag is easy to attach to the water-cooled wall of the secondary gasification chamber, and a slag block falls to block the horizontal flue, thereby finally causing the problems of damage of coal gasification equipment and low coal gasification efficiency.

Disclosure of Invention

The invention aims to solve the problems that the slag in the secondary gasification chamber of the existing coal gasification system is easy to attach to a water-cooled wall to form a large slag block, and the slag block blocks a horizontal flue when falling off to influence the safe operation of a gasification furnace; meanwhile, the problem that the temperature of synthesis gas at the inlet of the waste heat exchange chamber of the existing coal gasification system is high, so that the heating surface in the waste heat exchange chamber is burnt and the temperature of exhaust smoke is high is solved, and further the U-shaped coal gasification waste heat boiler with the spray cooling device and the cooling method are provided.

The technical scheme adopted by the invention for solving the problems is as follows:

the waste heat boiler comprises a waste heat boiler body, a gasification furnace body, a horizontal flue, a gasification furnace slag outlet and a slag pool; the waste heat boiler body comprises a secondary gasification chamber and a waste heat exchange chamber, and the secondary gasification chamber comprises a spraying system, a water supply system and a control system; the gasification furnace body is communicated with the secondary gasification chamber, a slag outlet of the gasification furnace is arranged in the slag pool, the waste heat exchange chamber is arranged close to the secondary gasification chamber, the gasification furnace body is communicated with the secondary gasification chamber through a horizontal flue, a convection heating surface is arranged in the waste heat exchange chamber, a synthetic gas outlet is arranged at the bottom of the convection heating surface, a synthetic gas inlet is arranged at the top of the convection heating surface, the spraying system is arranged on the outer side wall of the water-cooled wall of the secondary gasification chamber, the water supply system is communicated with the spraying system, and the spraying system and the water supply system.

The method is realized according to the following steps:

the method is realized according to the following steps:

the method comprises the following steps: when spraying, the DCS controller controls the spray head of the nozzle to extend, the spray head of the nozzle extends into a secondary gasification chamber hearth to spray water for cooling the synthesis gas and the molten slag, and when spraying is finished, the DCS controller controls the spray head of the nozzle to shorten and quit the secondary gasification chamber hearth to avoid high temperature damage to the nozzle;

step two: when the mixed gas flow of the synthesis gas and the liquid slag generated by the gasification furnace enters a secondary gasification chamber in the waste heat boiler, one part of slag is attached to the water-cooled wall of the secondary gasification chamber, and the other part of slag is changed into fly ash and then flows out from a synthesis gas outlet along with the synthesis gas;

step three: after the mixed gas flow of the synthesis gas and the liquid slag in the secondary gasification chamber is cooled by water spraying, the liquid slag is divided into three parts, and a small amount of slag in the first part flows with the synthesis gas in a mixed manner and enters the waste heat exchange chamber with the synthesis gas; the second part of slag is solidified into small slag blocks and falls to the bottom of the secondary gasification chamber; the third part of slag is adhered to the water wall of the secondary gasification chamber, some slag is washed and falls to the bottom, some slag is cracked into small slag blocks after being cooled and falls to the bottom, the small slag blocks falling from the bottom of the secondary gasification chamber are heated by high-temperature synthesis gas coming from the horizontal flue and liquid slag, the small slag blocks are melted to form new slag, the liquid slag from the gasification furnace and the new slag melted by the small slag blocks are mixed, and the mixture returns to the gasification furnace along the inclined horizontal flue and flows out from a slag outlet of the gasification furnace to enter a slag pool.

The invention has the beneficial effects that:

firstly, the invention can ensure the safety of the U-shaped coal gasification system in the operation process:

in the running process of the U-shaped coal gasification system, the spraying device for preventing the U-shaped coal gasification system from slagging can adopt air, nitrogen and the like as working media to reduce the temperature, if the air is adopted as the working media, because the air contains oxygen, when the temperature reaches the ignition condition, explosion is easily generated in the secondary gasification chamber, and the safety of the coal gasification production running process and personnel and equipment is seriously influenced; if the nitrogen is adopted as the working medium, the nitrogen is mixed into the synthesis gas, and the proportion of the effective gas hydrogen and the nitrogen in the mixed gas is reduced. The invention adopts water as the working medium, the water can be used as the gasifying agent to further react with carbon to generate carbon monoxide and hydrogen, and the possibility of explosion in a secondary gasification chamber which adopts air as the cooling working medium due to overhigh temperature and pressure is avoided. And by spraying in the secondary gasification chamber, the temperature in the secondary gasification chamber is effectively reduced to be lower than the melting temperature of molten slag, the formation of molten slag is effectively reduced, and the risk of the damage of the coal gasification equipment caused by the blockage of a large slag block formed by excessive molten slag at a synthesis gas inlet is reduced. In actual production, the temperature at the position of a synthesis gas inlet 20 is usually too high and far exceeds the designed value of 900 ℃, after waste heat is absorbed by a waste heat exchange chamber 21, the temperature of the synthesis gas at the position of a synthesis gas outlet 14 still reaches about 300 ℃, and far exceeds the designed outlet temperature of 180 ℃ and the running temperature of a bag-type dust collector by 250 ℃, so that the bag-type dust collector is damaged. The synthesis gas and the slag in the secondary gasification chamber 2 are sprayed, so that the synthesis gas is rapidly cooled, the temperature at the inlet 20 of the synthesis gas can reach the designed value of 900 ℃, after the waste heat is absorbed by the heat exchange chamber 21, the temperature of the synthesis gas at the outlet 14 of the synthesis gas can reach the designed outlet temperature of 180 ℃, and the safe operation of the bag-type dust collector can be ensured. The stability and the safety of the operation process of the coal gasification system are effectively improved.

Secondly, the invention can effectively increase the waste heat recovery efficiency of the convection heat exchange surface

According to the invention, the secondary gasification chamber is sprayed, water further reacts with carbon in fly ash to generate carbon monoxide and hydrogen, so that secondary gasification is effectively realized, and the yield of synthesis gas is increased; meanwhile, as water is vaporized at high temperature to generate a large amount of water vapor, the volume of gas in the secondary gasification chamber is increased, and the flow speed of mixed gas flow from the secondary gasification chamber to the waste heat exchange chamber is increased, so that the convection heat exchange coefficient of a convection heating surface in the waste heat exchange chamber is increased, and the waste heat recovery efficiency of the convection heat exchange chamber is improved.

Thirdly, the invention can reduce the operation and maintenance cost of the coal gasification device

During the operation of the U-shaped coal gasification device, ash and slag are easily accumulated in the secondary gasification chamber 2, and slag blocks fall to smash coal leakage gasification equipment and block the horizontal flue 10; the high temperature of the synthesis gas inlet 20 of the secondary gasification chamber 2 will burn the heating surface of the waste heat exchange chamber 21, which will lead to frequent start-up and shut-down of the coal gasification equipment. After the waste heat is absorbed by the waste heat exchange chamber 21, the temperature of the synthesis gas at the synthesis gas outlet 14 still reaches about 300 ℃ and exceeds the operation temperature of the bag-type dust remover by 250 degrees, so that the bag-type dust remover is damaged. Frequent start-up and shut-down of the coal gasification system will also result.

During the starting and stopping process of the gasification furnace 7, the slag blocks blocked by the horizontal flue 10 are cleaned, the water-cooled wall of the horizontal flue, the heating surface of the waste heat exchange chamber 21 and the bag-type dust remover are replaced, a large amount of material cost, installation cost, labor cost and fuel cost are generated, and the economic benefit of the coal gasification production process is greatly reduced; meanwhile, the coal gasification system is shut down and maintained, so that normal production is influenced, and the economic and credit of enterprises are greatly influenced. According to the invention, the synthesis gas and the slag are sprayed by taking water as a working medium in the secondary gasification chamber 2, and the temperature in the secondary gasification chamber is reduced to be below the melting temperature, so that the formation of the slag is effectively reduced, the blockage at the outlet of the horizontal flue 10 is prevented, the temperatures at the synthesis gas inlet 20 and the synthesis gas outlet 14 of the secondary gasification chamber 2 are reduced, the design values are reached, the damage of the heating surface of the waste heat exchange chamber 21 and the damage of a bag-type dust collector are avoided, the furnace shutdown hidden danger of the coal gasification system is greatly reduced, the operation period of the coal gasification system is prolonged, the influence of frequent furnace startup and shutdown on the coal gasification production process is reduced, and the cost required by the operation and maintenance. Thereby ensuring the stable operation of the coal gasification system and laying a good foundation for the coal chemical production.

Drawings

FIG. 1 is a schematic overall structure of the present application;

FIG. 2 is a view taken along line A-A of FIG. 1;

FIG. 3 is an enlarged view at B in FIG. 1;

fig. 4 is a schematic view of the end face shape of the jet of the nozzle of fig. 1.

Detailed Description

The first embodiment is as follows: the embodiment is described with reference to fig. 1 to 4, and the U-shaped coal gasification waste heat boiler with a spray cooling device according to the embodiment comprises a waste heat boiler body 1, a gasification furnace body 7, a horizontal flue 10, a gasification furnace slag hole 12 and a slag bath 13; the waste heat boiler body 1 includes secondary gasification room 2 and waste heat exchange chamber 21, its characterized in that: the secondary gasification chamber 2 comprises a spraying system, a water supply system and a control system; the gasification furnace body 7 is communicated with the secondary gasification chamber 2, the slag outlet 12 of the gasification furnace is arranged in the slag pool 13, the waste heat exchange chamber 21 is arranged close to the secondary gasification chamber 2, the gasification furnace body 7 is communicated with the secondary gasification chamber 2 through the horizontal flue 10, the convection heating surface 16 is arranged in the waste heat exchange chamber 21, the bottom of the convection heating surface 16 is a synthetic gas outlet 14, the top of the convection heating surface 16 is provided with a synthetic gas inlet 20, the spraying system is arranged on the outer side wall of the water-cooled wall of the secondary gasification chamber 2, the water supply system is communicated with the spraying system, and the spraying system and the water supply system are both connected with the.

The second embodiment is as follows: the embodiment is described with reference to fig. 1 and 2, and the U-shaped coal gasification waste heat boiler with a spray cooling device in the embodiment includes a plurality of connection flanges 3, a plurality of supports 17, a plurality of nozzles 18 and a plurality of spray water pipes 19, wherein one connection flange 3 is respectively installed at two ends of each spray water pipe 19, the plurality of spray water pipes 19 are installed on the secondary gasification chamber 2 from top to bottom, the plurality of nozzles 18 are installed on the spray water pipes 19 along the peripheral direction, and the spray water pipes 19 are installed on the outer wall of the water wall of the secondary gasification chamber 2 through the plurality of supports 17. Other structures and methods are the same as those of the first embodiment.

In this embodiment, the number of the shower pipes 19 is one to eight from the top to the bottom.

The third concrete implementation mode: referring to fig. 1, the embodiment is described, and a water supply system of a U-shaped coal gasification waste heat boiler with a spray cooling device according to the embodiment includes a water pump 11, an inlet pipe 5 and an outlet pipe 6, the water pump 11 is installed on the inlet pipe 5, the inlet pipe 5 is communicated with an inlet end of a spray water pipe 19, and an outlet end of the spray water pipe 19 is communicated with the outlet pipe 6. Other structures and methods are the same as those of the first embodiment.

The fourth concrete implementation mode: the embodiment is described with reference to fig. 1 and 3, and the control system of the U-shaped coal gasification waste heat boiler with a spray cooling device in the embodiment includes a DCS controller 15, a flowmeter 4, a plurality of high-temperature thermocouples 9, a plurality of medium-temperature thermocouples 22 and a plurality of electric valves 8, wherein each spray water pipe 19 is provided with one flowmeter 4 and one electric valve 8, the plurality of high-temperature thermocouples 9 are installed on the water-cooled wall of the secondary gasification chamber 2, the plurality of medium-temperature thermocouples 22 are arranged around the synthesis gas inlet 20, and the DCS controller 15 is connected with the flowmeter 4, the high-temperature thermocouples 9, the water pump 11, the medium-temperature thermocouples 22 and the electric valves 8. Other structures and methods are the same as those of the first embodiment.

The fifth concrete implementation mode: the embodiment is described with reference to fig. 1 and 4, in the U-shaped coal gasification waste heat boiler with a spray cooling device, the spray water pipes 19 are rectangular frames, the number of the connecting flanges 3 is three, the three spray water pipes 19 are arranged on the outer side wall of the water wall of the secondary gasification chamber 2 at equal intervals from top to bottom, the distance from the nozzle 18 on the top spray water pipe 19 to the synthesis gas inlet 20 is L1, the distance between two adjacent spray water pipes 19 is L2, the distance from the nozzle 18 on the bottom spray water pipe 19 to the bottom of the secondary gasification chamber 2 is L3, the distance from the center line of two adjacent nozzles 18 on the frame of each spray water pipe 19 is M, the nozzle jet flow contraction section diameter of the nozzle 18 is a, and the numerical values of M, L1, L2 and L3 are all less than or equal to one half of a. Other structures and methods are the same as those of the first embodiment.

The sixth specific implementation mode: the embodiment is described with reference to fig. 1, fig. 2 and fig. 4, and the U-shaped coal gasification waste heat boiler with a spray cooling device according to the embodiment has a rectangular cross section of the secondary gasification chamber 2, the side length of the furnace of the secondary gasification chamber 2 is I, the product of the number of nozzles 18 on each side of the spray header 19 and the diameter value of the nozzle jet flow contraction cross section of the nozzles 18 is greater than or equal to each side length I of the furnace of the secondary gasification chamber 2, the range of the nozzles 18 is b, b is greater than or equal to one half of I, the distance between the edge nozzles 18 on the spray header 19 and the edge of the frame of the spray header 19 is N, and N is less than or equal to one half of a. Other structures and methods are the same as those of the first embodiment.

The seventh embodiment: referring to fig. 1, the embodiment is described, and the nozzles 18 of the U-shaped coal gasification waste heat boiler with the spray cooling device in the embodiment are atomizing nozzles, the angle formed by the central line of each nozzle 18 and the horizontal plane is 0-15 degrees, and the nozzles 18 are inclined upwards by 0-15 degrees or downwards by 0-15 degrees. Other structures and methods are the same as those of the first embodiment.

The specific implementation mode is eight: the present embodiment is described with reference to fig. 1 to 4, and the method for cooling a U-shaped coal gasification waste heat boiler with a spray cooling device according to the present embodiment is implemented according to the following steps:

the method comprises the following steps: when spraying, the DCS controller 15 controls the spray head of the nozzle 18 to extend, the spray head of the nozzle 18 extends into the hearth of the secondary gasification chamber 2 to spray water for cooling the synthetic gas and the molten slag, and when spraying is finished, the DCS controller 15 controls the spray head of the nozzle 18 to shorten and quit the hearth of the secondary gasification chamber 2 to avoid the nozzle 18 from being damaged by high temperature;

step two: when the mixed gas flow of the synthesis gas and the liquid slag generated by the gasification furnace enters the secondary gasification chamber 2 in the waste heat boiler 1, one part of slag is attached to the water-cooled wall of the secondary gasification chamber 2, and the other part of slag is changed into fly ash and then flows out from a synthesis gas outlet 14 along with the synthesis gas;

step three: after the mixed gas flow of the synthesis gas and the liquid slag in the secondary gasification chamber 2 is cooled by water spraying, the liquid slag is divided into three parts, a small amount of slag in the first part flows with the synthesis gas in a mixed way and enters the waste heat exchange chamber 21 with the synthesis gas; the second part of slag is solidified into small slag blocks and falls to the bottom of the secondary gasification chamber 2; the third part of the slag is adhered to the water-cooled wall of the secondary gasification chamber 2, some slag is washed and falls to the bottom, some slag is exploded into small slag blocks after being cooled and falls to the bottom, the small slag blocks falling from the bottom of the secondary gasification chamber 2 are heated by high-temperature synthetic gas coming from the horizontal flue 10 and liquid slag, the small slag blocks are melted to form new slag, the liquid slag from the gasification furnace and the new molten slag melted by the small slag blocks are mixed, and the mixture returns to the gasification furnace 7 along the inclined horizontal flue 10 and flows out from a slag outlet 12 of the gasification furnace to enter a slag pool 13.

The specific implementation method nine: referring to fig. 1, the embodiment is described, and a method for cooling a U-shaped coal gasification waste heat boiler with a spray cooling device according to the embodiment includes a first step of transmitting a signal to a DSC controller 15 by a high-temperature thermocouple 9 or a medium-temperature thermocouple 22 when the temperature of synthesis gas detected by the high-temperature thermocouple 9 in a secondary gasification chamber 2 is higher than 1300 ° or the temperature detected by the medium-temperature thermocouple 22 is higher than 900 °, controlling a water pump 11 and an electric valve 8 to be opened by the DCS controller 15, allowing spray water to enter a water inlet pipe 5, controlling a nozzle 18 to extend by the controller 15, allowing the nozzle 18 to extend into a furnace chamber of the secondary gasification chamber 2 to spray water for cooling, transmitting a signal to the DSC controller 15 by the high-temperature thermocouple 9 or the medium-temperature thermocouple 22 when the temperature of synthesis gas detected by the high-temperature thermocouple 9 in the secondary gasification chamber 2 is lower than or equal to 1300 °, the DCS controller 15 controls the nozzle 18 to be shortened, the secondary gasification chamber 2 is quitted from the hearth, the water pump 11 and the electric valve 8 are gradually closed, and the residual water flow flows out from the water outlet pipe 6. Other structures and methods are the same as those of the first embodiment.

The detailed implementation mode is ten: in the cooling method of the U-shaped coal gasification waste heat boiler with the spray cooling device according to the second embodiment, the synthesis gas and a small amount of slag in the secondary gasification chamber 2 enter the waste heat exchange chamber 21 through the synthesis gas inlet 20 at the upper part of the secondary gasification chamber 2, energy is transferred in the waste heat exchange chamber 21 through the convection heating surface, and the slag is converted into fly ash and flows out from the synthesis gas outlet 14 along with the synthesis gas. Other structures and methods are the same as those of the first embodiment.