Horizontal flat flame gasifier, boiler stable combustion system and boiler stable combustion method

Abstract

The present invention relates to the technical field of boiler combustion, and discloses a horizontal flat flame gasifier, a boiler combustion stabilization system, and a method for stabilizing the combustion of a boiler under abnormal load. The gasifier comprises a burner device, a plasma ignition device, and a combustion chamber; wherein the burner device is arranged in the combustion chamber, comprising a nozzle and at least three feeding units arranged in the nozzle, and the outlet end nozzles of the feeding units are evenly distributed in the circumferential direction on the outlet end surface of the nozzle, and the outlet end nozzles of the feeding units are tilted 2-15° in the horizontal direction. The method for stabilizing the combustion of a boiler under abnormal load provided by the present invention can stabilize the combustion temperature of the main combustion zone of the boiler at above 800°C, and can realize stable combustion of the boiler under low load or ultra-low load.

Description

Technical Field

[0001] The invention relates to the technical field of boiler combustion, and in particular to a horizontal flat-flame gasifier, a boiler combustion stabilization system and a boiler combustion stabilization method under abnormal load. Background Art

[0002] The goal of "carbon peak in 2030, carbon neutrality in 2060" has increased the grid's demand for renewable energy generation, such as photovoltaic, wind power, and hydropower, and has also put forward more stringent requirements for the grid's deep peak regulation. In order to enable a large amount of renewable energy to be connected to the grid, power plant boilers are adjusted to operate at low or ultra-low loads. How to ensure that existing power plant boilers can operate stably at low or ultra-low loads without safety accidents such as shutdowns has become a technical problem faced by all power plants.

[0003] The current solution is to add an oil burner to the existing power plant boiler side, similar to a perpetual lamp, and increase the load of the oil burner to ensure the stable combustion of the power plant boiler system. Although this technical solution has played a good role in ensuring the stable and safe operation of the system, due to the high price of oil and the fact that the charge of the oil smoke generated by oil combustion is not within the dust removal range of the electrostatic precipitator, it is impossible to use the existing electrostatic precipitator for dust removal. In order to meet environmental protection requirements, a separate dust removal device needs to be matched, which increases the complexity of the entire system and the operating cost of the power plant. Therefore, it is particularly important to use the inherent resources of the power plant to develop an economically feasible stable combustion technology for power plant boilers at low or ultra-low loads.

[0004] CN108518666 A describes a pulverized coal boiler stable combustion system and method using coal as fuel. The system includes a gasifier body, a pulverized coal boiler and a first steam drum. The gasifier body adopts a vertical gasifier, and the gasifier is divided into a gasification section, a radiation waste boiler section and a slag pool section from top to bottom. Pulverized coal and gasifying agent undergo pyrolysis and gasification reaction under high temperature environment to produce coal gas and ash particles. The coal gas and a part of the ash particles enter the stable gas burner through the stable gas pipeline, and the other part of the ash particles fall into the slag pool section and are discharged through the slag discharge pipeline. Although the system has low-load operation and deep peak regulation capabilities, and can meet the needs of maintaining the long-term low-load operation of the pulverized coal boiler at low cost. However, the gasifier in the system is a vertical gasifier. If the coal gas and ash particles generated by the reaction of the gasifier are to be smoothly transported to the pulverized coal boiler, there are great difficulties in pneumatic transportation by the gasifier itself. This is because the movement direction of the coal gas and ash particles is vertical, and the transportation to the pulverized coal boiler requires horizontal transportation. In order to change the direction of transportation, it is necessary to add material turning equipment. However, the temperature of coal gas is generally high, and the high temperature resistance of fans or pumps is relatively poor, and they cannot be used for high temperature coal gas turning. Therefore, this patent is basically impossible to implement in reality.

[0005] CN207674428U describes a coal-fired unit coupled with biomass gasification power generation and gas combustion system, which includes a circulating fluidized bed, a separation device, a heat exchanger, and a pressurizing device. The system uses a circulating fluidized bed for gasification and then replaces the existing petroleum combustion system with synthetic gas after a series of post-treatments to ensure stable combustion of the system. This patent uses a circulating fluidized bed, and this patent only transports the synthetic gas generated by the gasifier to the pulverized coal boiler for combustion. According to this patent, the purpose of transporting pulverized coal to the pulverized coal boiler for gasification cannot be achieved. Summary of the invention

[0006] The purpose of the present invention is to overcome the problem of high operating cost of stable combustion of power plant boilers under low load or ultra-low load in the prior art, and to provide a horizontal flat flame gasifier, a boiler stable combustion system and a method for stabilizing combustion of the boiler under abnormal load. The method for stabilizing combustion of the boiler under abnormal load provided by the present invention has the advantages of low operating cost and good combustion stability.

[0007] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a horizontal flat-flame gasifier, wherein the gasifier includes a burner device, a plasma ignition device and a combustion chamber; wherein the burner device is arranged in the combustion chamber, including a nozzle and at least three feeding units arranged in the nozzle, the outlet end nozzles of the feeding units are evenly distributed in the circumferential direction on the outlet end surface of the nozzle, and the outlet end nozzles of the feeding units are tilted 2-15° in the horizontal direction.

[0008] The second aspect of the present invention provides a boiler stable combustion system, wherein the system includes a horizontal flat flame gasifier and a boiler; wherein the horizontal flat flame gasifier is the gasifier described in the first aspect of the present invention, and the outlet of the horizontal flat flame gasifier is horizontally connected to the fuel inlet of the boiler.

[0009] The third aspect of the present invention provides a method for stabilizing combustion of a boiler under abnormal load, wherein the method comprises first subjecting the fuel and the gasifying agent to an incomplete gasification reaction, and then feeding the reaction mixture into the boiler for combustion; wherein the abnormal load comprises a low load and an ultra-low load; the method is carried out in the boiler stabilizing combustion system described in the second aspect of the present invention; and the temperature of the incomplete gasification reaction is 1000-1200°C.

[0010] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0011] 1) The horizontal flat-flame gasifier provided by the present invention has the advantages of fast reaction speed, short flame, wide adaptability to coal types, and can effectively gasify low calorific value fuels, thereby improving the stability of boiler combustion;

[0012] 2) The horizontal flat flame gasifier provided by the present invention increases the service life of the refractory bricks of the gasifier by changing the arrangement of the nozzles at the outlet end;

[0013] 3) The horizontal flat flame gasifier provided by the present invention adopts plasma ignition, which meets the requirement of the whole device for rapid ignition;

[0014] 4) The boiler combustion stabilization system provided by the present invention can use the horizontal flat flame gasifier as a ventilation duct for the primary air required for boiler combustion by switching the valve when the pulverized coal boiler is operating under normal load, thereby ensuring the compact layout and cost control of the entire device; when the pulverized coal boiler is operating under low load or ultra-low load, the fuel is incompletely gasified under the action of the gasifying agent by coupling the horizontal flat flame gasifier with the boiler to generate a high-temperature mixed gas (CO, CH4, H2, tar, etc.) and incompletely gasified fuel; the mixture containing the high-temperature mixed gas, incompletely gasified fuel, fuel that has not participated in the reaction, and the carrier gas obtained after the incomplete gasification treatment is horizontally transported to the boiler under pressure, and since the mixed gas and incompletely gasified fuel are easy to ignite, the problem of incomplete combustion or failure to ignite caused by directly transporting cold fuel to the boiler under low load or ultra-low load is avoided;

[0015] 5) The pulverized coal boiler stable combustion system provided by the present invention does not require an additional oil / gas combustion-supporting system, and the subsequent dust removal system can be used normally without adding or modifying the dust removal system of the original device, thereby significantly reducing the operating cost of the device;

[0016] 6) The stable combustion method of the boiler under abnormal load provided by the present invention controls the gasification temperature below the ash melting point, so that no slag is produced when the fuel undergoes an incomplete gasification reaction in the flat flame gasifier, and the incompletely gasified mixture is conveniently transported to the boiler to ensure the stable combustion of the boiler system, and at the same time, the slag can be prevented from falling into the combustion chamber and corroding the refractory bricks;

[0017] 7) The method for stabilizing combustion of a boiler under abnormal load provided by the present invention can overcome the technical difficulties of traditional stabilizing combustion control technology, such as the need for a subsequent dust removal system for stabilizing the combustion of synthetic gas in a gasifier, the high price of gasoline / diesel, the inability of vertical gasification to transport entrained particles to a pulverized coal boiler, etc., the complex equipment, unstable operation, difficulty in starting and stopping, slow start and stop, high operating cost, etc., and is suitable for industrial promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a horizontal flat flame gasifier in a preferred embodiment provided by the present invention;

[0019] Figure 2 It is a schematic diagram of a right side view of a burner device in a preferred embodiment provided by the present invention;

[0020] Figure 3 It is a schematic diagram of a nozzle at the outlet end of a feeding unit in a preferred embodiment provided by the present invention;

[0021] Figure 4 It is a structural schematic diagram of a boiler combustion stabilization system in a preferred embodiment provided by the present invention.

[0022] Description of Reference Numerals

[0023] DETAILED DESCRIPTION

[0024] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0025] The terms "upper" and "lower" used in the present invention are Figure 1 The X direction in the figure is used as a reference for determination, the direction along the X direction is "up", and the opposite direction is "down". Stable combustion in the present invention means that the combustion temperature of the main combustion zone of the boiler can be stabilized at above 800°C.

[0026] The first aspect of the present invention provides a horizontal flat flame gasifier, the gasifier comprising a burner device 1, a plasma ignition device 2 and a combustion chamber 3, such as Figure 1 As shown; wherein the burner device 1 is arranged in the combustion chamber 3, including a nozzle 11 and at least three feeding units arranged in the nozzle 11, and the outlet end nozzles 12 of the feeding unit are evenly distributed along the circumferential direction on the outlet end surface of the nozzle 11, as shown Figure 2 As shown, the outlet nozzle 12 of the feed unit is tilted 2-15° in the horizontal direction, as shown in FIG. Figure 3 shown.

[0027] Among them, the horizontal flat flame type gasifier in the present invention is used for incomplete gasification of fuel. The motion trajectory of the incompletely gasified fuel generated after the reaction in the combustion chamber is a parabola. If it is arranged in a conventional horizontal manner, the refractory bricks at the bottom of the gasifier are more likely to be corroded, affecting the service life and stability of the system. In the present invention, the outlet end nozzles of the feed unit are evenly distributed along the circumferential direction on the outlet end surface of the nozzle and the outlet end nozzles of the feed unit are tilted 2-15° in the horizontal direction, which can change the motion trajectory of the incompletely gasified fuel and play a certain protective role on the refractory bricks at the bottom of the combustion chamber, thereby solving the problem of short service life of refractory bricks in the horizontal flat flame type gasifier.

[0028] In a preferred embodiment, the present invention does not impose any special limitation on the number of the feed units. Preferably, the burner device 1 includes three feed units.

[0029] In a preferred embodiment, the feed unit comprises a fuel pipeline and at least two gasifying agent pipelines, wherein a convergence point of the gasifying agent sprayed from the gasifying agent pipeline falls on the fuel sprayed from the fuel pipeline.

[0030] In a further preferred embodiment, the present invention does not impose any special limitation on the number of gasifying agent pipelines, and the number of gasifying agent pipelines may be 2-6, preferably 2-3.

[0031] In a preferred embodiment, the outlet nozzle 12 of the feed unit includes a fuel pipeline nozzle 121 and a gasifying agent pipeline nozzle 122 ; wherein the gasifying agent pipeline nozzle 122 is evenly distributed along the fuel pipeline nozzle 121 .

[0032] In the present invention, when the feed unit includes a fuel pipeline and three gasifying agent pipelines, the gasifying agent pipeline nozzles are distributed in a regular triangle on the nozzle end surface, and the fuel pipeline nozzle is located at the center of the regular triangle surrounded by the gasifying agent pipeline nozzles.

[0033] In a preferred embodiment, the angle between the injection direction of the gasifying agent pipeline nozzle 122 and the injection direction of the fuel pipeline nozzle 121 is 30-60°, preferably 40-50°.

[0034] In a preferred embodiment, a cooling liquid coil is further provided at the outlet nozzle 12 of the feeding unit, and the cooling liquid coil is used to cool the nozzle.

[0035] In a preferred embodiment, the fuel sprayed from the fuel pipeline nozzle 121 in the feeding unit and the gasifying agent sprayed from the gasifying agent pipeline nozzle 122 both intersect on plane A, and the ion ignition device 2 is arranged on the combustion chamber 3 and is located at the junction of the plane A and the combustion chamber 3.

[0036] Among them, in the present invention, the fuel and the gasifying agent sprayed from the burner device in an oblique upward direction intersect and contact each other, and are ignited by the plasma ignition device, so that an incomplete gasification reaction occurs to generate a high-temperature mixed gas and incompletely gasified fuel.

[0037] In a preferred embodiment, a boost air inlet 4 is further provided on the combustion chamber 3 ; wherein the boost air inlet 4 is provided at the bottom of the combustion chamber 3 , close to the outlet of the combustion chamber 3 .

[0038] In a preferred embodiment, the distance between the boost air inlet 4 and the combustion chamber outlet is 20%-40% of the combustion chamber length, preferably 25-35%. The boost air inlet refers to the inlet of the boost air inlet on the outer wall of the combustion chamber.

[0039] In a preferred embodiment, in the horizontal direction from the inlet to the outlet of the combustion chamber 3, the angle between the boost air inlet 4 and the bottom of the combustion chamber 3 is 30-60°, preferably 40-50°.

[0040] Among them, in the present invention, a certain amount of gasifying agent is blown obliquely upward from the rear half of the combustion chamber by utilizing the booster air inlet. On the one hand, it can further prevent incompletely gasified fuel from falling into the lower part of the combustion chamber to corrode the refractory bricks. On the other hand, it can increase the oxygen content in the mixture coming out of the combustion chamber, which can have a combustion-aiding effect.

[0041] In a preferred embodiment, the combustion chamber 3 is cylindrical. A square combustion chamber has sharp corners and stress concentration, and is generally difficult to use as a reaction device for coal pulverized gasification. To avoid cracking of the combustion chamber, the present invention preferably sets the combustion chamber to be cylindrical.

[0042] In a preferred embodiment, the combustion chamber 3 is made of refractory bricks, and a thermocouple 5 is arranged on the wall of the combustion chamber 3 for monitoring the temperature of the combustion chamber.

[0043] In a preferred embodiment, the gasifier further comprises a discharge pipe 6, and the discharge pipe 6 is used to deliver the mixture from the combustion chamber out of the fuel chamber.

[0044] In a preferred embodiment, refractory bricks are arranged outside the burner device and the discharge pipe.

[0045] The second aspect of the present invention provides a boiler stable combustion system, the system comprising a horizontal flat flame gasifier and a boiler; wherein the horizontal flat flame gasifier is the gasifier described in the first aspect of the present invention, and the outlet of the horizontal flat flame gasifier is horizontally connected to the fuel inlet of the boiler, such as Figure 4 shown.

[0046] The third aspect of the present invention provides a method for stabilizing combustion of a boiler under abnormal load, wherein the method comprises first subjecting the fuel and the gasifying agent to an incomplete gasification reaction, and then feeding the reaction mixture into the boiler for combustion; wherein the abnormal load comprises a low load and an ultra-low load; the method is carried out in the boiler stabilizing combustion system described in the second aspect of the present invention; and the temperature of the incomplete gasification reaction is 1000-1200°C.

[0047] Among them, the incomplete gasification reaction in the present invention refers to the fuel without slag generation during the reaction process. In the present invention, the fuel and the gasifier are ignited in a horizontal flat flame gasifier using a plasma electric fire device, and an incomplete gasification reaction is carried out at 1000-1200°C, so that the fuel can undergo an incomplete gasification reaction without generating slag, and generate a mixed gas and an incompletely gasified fuel. The generated mixed gas carries the incompletely gasified fuel and the fuel that does not participate in the reaction and is directly transported horizontally to the boiler for combustion, which can play a role in supporting combustion, thereby solving the problem of incomplete combustion or failure to ignite the fuel directly delivered to the boiler in the prior art, resulting in the furnace stopping; the generated incompletely gasified fuel, due to the precipitation of volatile matter, leads to an increase in the porosity of the incompletely gasified fuel, further reducing the difficulty of igniting the incompletely gasified fuel in the boiler, which can further increase the combustion-supporting effect and improve the stability of boiler operation.

[0048] In a preferred embodiment, the low load means that the boiler operating load is 35-50% (including 35%) of the boiler rated load; the ultra-low load means that the boiler operating load is 15-35% (excluding 35%) of the boiler rated load.

[0049] In a preferred embodiment, the particle size of the fuel is ≤2 mm, preferably 20-100 μm; the water content of the fuel is ≤5 wt%, preferably 1-3 wt%.

[0050] In a preferred embodiment, the fuel is selected from coal powder and / or biomass powder, preferably coal powder. The biomass powder in the present invention has a well-known meaning in the art, and the present invention does not specifically limit the biomass powder.

[0051] In a preferred embodiment, the fuel enters the horizontal flat-flame gasifier under the influence of a carrier gas; wherein the carrier gas is selected from nitrogen and / or carbon dioxide.

[0052] In a preferred embodiment, the pressure of the carrier gas is 0.5-4 MPa, preferably 3-4 MPa.

[0053] In a preferred embodiment, the mass ratio of the fuel to the carrier gas is 10-30:1, preferably 15-25:1.

[0054] In a preferred embodiment, the gasifying agent is selected from air and / or oxygen, preferably oxygen.

[0055] In a preferred embodiment, the pressure of the gasifying agent is 5-10 MPa, preferably 6-8 MPa.

[0056] In a preferred embodiment, the mass ratio of the fuel to the gasifying agent is 500:0.5-2, preferably 500:0.9-1.1.

[0057] Among them, by controlling the mass ratio of the fuel and the gasifying agent, the fuel can be incompletely gasified under the gasification conditions, thereby avoiding complete gasification and preventing the generation of ash.

[0058] In a preferred embodiment, the injection speed of the fuel is 3-10 m / s, preferably 5-7 m / s; the injection speed of the gasifying agent is 50-80 m / s, preferably 60-70 m / s.

[0059] In a preferred embodiment, the plasma arc temperature in the plasma ignition device is 2000-7000K, preferably 3000-6000K.

[0060] Among them, in the present invention, the plasma igniter releases a plasma arc of 3000-6000K, which can provide initial heat for incomplete gasification of the fuel. When the heat released by the incomplete gasification of the fuel can ensure the stable gasification, the plasma ignition device is turned off, which can avoid accidents such as parking caused by failure of the plasma ignition device.

[0061] In a preferred embodiment, the temperature of the incomplete gasification reaction is 1000-1100°C, and the pressure of the incomplete gasification reaction is 3-4MPa. When the incomplete gasification temperature is 1000-1100°C and the pressure is 3-4MPa, the boiler has a better stable combustion effect.

[0062] In a preferred embodiment, the mixture includes a mixed gas, an incompletely gasified fuel and a fuel that does not participate in the reaction; wherein the mixed gas includes a carrier gas, a gasifying agent that does not participate in the reaction, and CO, CH4, H2 and tar generated by the reaction.

[0063] Among them, in the present invention, the mixture after the incomplete gasification reaction directly enters the boiler, which can reduce heat loss, increase the feed temperature entering the boiler, avoid the risk of boiler shutdown caused by directly entering the boiler with cold fuel in the prior art, and improve the stability of boiler combustion.

[0064] In a preferred embodiment, in the combustion, the ratio of the mixture to the secondary air is 100:20-30, preferably 100:5-20.

[0065] Among them, the stable combustion method of the boiler under abnormal load provided by the present invention can stabilize the combustion temperature of the main combustion zone of the boiler at above 800°C, and can achieve stable combustion of the boiler under low load or ultra-low load.

[0066] The present invention will be described in detail below by way of examples. Figure 4 The boiler stable combustion system shown in the figure includes a 300MW subcritical boiler and a horizontal flat flame gasifier;

[0067] The horizontal flat flame gasifier comprises a burner device, a plasma ignition device, a combustion chamber and a discharge pipe; wherein the burner device is arranged in the combustion chamber, comprising a nozzle and three feeding units arranged in the nozzle, the outlet end nozzles of the three feeding units are evenly distributed along the circumferential direction on the outlet end surface of the nozzle, and the outlet end nozzles of the feeding units are tilted 5° in the horizontal direction;

[0068] The feed unit includes a fuel pipeline and three gasifying agent pipelines. The angle between the injection direction of the gasifying agent pipeline nozzle and the injection direction of the fuel pipeline nozzle is 45°. The inner diameter of the gasifying agent pipeline nozzle is 6.8 mm and is distributed in a regular triangle on the end face of the nozzle. The inner diameter of the fuel pipeline nozzle is 9 mm and is located at the center of the regular triangle surrounded by the gasifying agent pipeline nozzles. A coolant coil is provided at the outlet nozzle of the feed unit.

[0069] The fuel sprayed from the nozzles of the fuel pipelines and the gasifying agent sprayed from the nozzles of the gasifying agent pipelines in the three feeding units all intersect on plane A. The ion ignition device is arranged on the combustion chamber and is located at the junction of plane A and the combustion chamber.

[0070] The combustion chamber is cylindrical and made of refractory bricks. A thermocouple is arranged on the combustion chamber wall. The booster air inlet is arranged at the bottom of the combustion chamber, close to the combustion chamber outlet, and the distance from the combustion chamber outlet is 30% of the combustion chamber length. In the horizontal direction from the combustion chamber inlet to the outlet, the included angle between the booster air inlet and the bottom of the combustion chamber is 30°.

[0071] The horizontal flat-flame gasifier is horizontally connected to the 300MW subcritical boiler through a discharge pipe.

[0072] Example 1

[0073] The carrier gas carries the fuel and is sprayed into the combustion chamber from the nozzle of the fuel pipeline. The gasifying agent is sprayed into the combustion chamber from the nozzle of the gasifying agent pipeline. The injected fuel and the gasifying agent collide and contact, and are incompletely gasified after plasma ignition to obtain a mixture including a mixed gas, incompletely gasified fuel and fuel that has not participated in the reaction. Air is blown obliquely upward from the booster air inlet to assist in transporting the obtained mixture, so that the mixture is directly transported horizontally to the boiler and burned after mixing with the secondary air. The specific operating conditions are shown in Table 1.

[0074] Example 2

[0075] The same as Example 1, the difference is that the operating conditions are different, as shown in Table 1.

[0076] Table 1

[0077]

[0078] Among them, the stable combustion method of the boiler under abnormal load provided by the present invention can stabilize the combustion temperature of the boiler at above 800°C, and can achieve stable combustion of the boiler under low load or ultra-low load.

[0079] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A horizontal flat flame gasifier, characterized in that: The gasifier comprises a burner device, a plasma ignition device and a combustion chamber; wherein the burner device is arranged in the combustion chamber, comprises a nozzle and at least three feeding units arranged in the nozzle, the outlet end nozzles of the feeding units are evenly distributed along the circumferential direction on the outlet end surface of the nozzle, and the outlet end nozzles of the feeding units are tilted 2-15° in the horizontal direction; Wherein, the feed unit comprises a fuel pipeline and at least two gasifying agent pipelines, and the intersection point of the gasifying agent sprayed from the gasifying agent pipeline falls on the fuel sprayed from the fuel pipeline; The outlet end nozzle of the feed unit includes a fuel pipeline nozzle and a gasifying agent pipeline nozzle, and the gasifying agent pipeline nozzles are evenly distributed along the fuel pipeline nozzle; The angle between the injection direction of the gasifying agent pipeline nozzle and the injection direction of the fuel pipeline nozzle is 30-60°.

2. The horizontal flat flame gasifier according to claim 1, wherein: The angle between the injection direction of the gasifying agent pipeline nozzle and the injection direction of the fuel pipeline nozzle is 40-50°.

3. The horizontal flat flame gasifier according to claim 1, wherein: The intersection point of the fuel sprayed from the fuel pipeline nozzle in the feeding unit and the gasifying agent sprayed from the gasifying agent pipeline nozzle is on the same plane as the plasma ignition device arranged on the combustion chamber.

4. The horizontal flat flame gasifier according to claim 1 or 2, wherein: A boost air inlet is also provided on the combustion chamber; the boost air inlet is provided at the bottom of the combustion chamber, close to the combustion chamber outlet.

5. The horizontal flat flame gasifier according to claim 1 or 2, wherein: The distance between the boost air inlet and the combustion chamber outlet is 20%-40% of the combustion chamber length.

6. The horizontal flat flame gasifier according to claim 5, wherein: The distance between the boost air inlet and the combustion chamber outlet is 25-35% of the combustion chamber length.

7. The horizontal flat flame gasifier according to claim 1 or 2, wherein: In the horizontal direction from the inlet to the outlet of the combustion chamber, the angle between the boost air inlet and the bottom of the combustion chamber is 30-60°.

8. The horizontal flat flame gasifier according to claim 7, wherein: In the horizontal direction from the inlet to the outlet of the combustion chamber, the angle between the boost air inlet and the bottom of the combustion chamber is 40-50°.

9. A boiler combustion stabilization system, characterized in that: The system comprises a horizontal flat-flame gasifier and a boiler; wherein the horizontal flat-flame gasifier is the gasifier according to any one of claims 1 to 8, and an outlet of the horizontal flat-flame gasifier is horizontally connected to a fuel inlet of the boiler.

10. A method for stabilizing combustion of a boiler under abnormal load, characterized in that: The method comprises first subjecting the fuel and the gasifying agent to an incomplete gasification reaction, and then sending the reaction mixture into a boiler for combustion; wherein the abnormal load comprises a low load and an ultra-low load; the method is carried out in the boiler stable combustion system as described in claim 9; the temperature of the incomplete gasification reaction is 1000-1200°C.

11. The method according to claim 10, wherein: The low load refers to the boiler operating load being 35-50% of the boiler rated load; the ultra-low load refers to the boiler operating load being 15-35% of the boiler rated load.

12. The method according to claim 10, wherein: The particle size of the fuel is ≤2 mm, and the water content of the fuel is ≤5 wt %.

13. The method according to claim 12, wherein: The particle size of the fuel is 20-100 μm; the water content of the fuel is 1-3 wt %.

14. The method according to claim 10, wherein: The fuel is selected from coal powder and / or biomass powder.

15. The method according to claim 14, wherein: The fuel is pulverized coal.

16. The method according to claim 10, wherein: The fuel is carried by a carrier gas into a horizontal flat-flame gasifier; wherein the carrier gas is selected from nitrogen and / or carbon dioxide.

17. The method according to claim 16, wherein: The pressure of the carrier gas is 0.5-4 MPa.

18. The method according to claim 17, wherein: The pressure of the carrier gas is 3-4 MPa.

19. The method according to claim 16, wherein: The mass ratio of the fuel to the carrier gas is 10-30:

1.

20. The method according to claim 19, wherein: The mass ratio of the fuel to the carrier gas is 15-25:

1.

21. The method according to claim 10, wherein: The gasifying agent is selected from air and / or oxygen.

22. The method according to claim 21, wherein: The gasifying agent is oxygen.

23. The method according to claim 10, wherein: The pressure of the gasifying agent is 5-10 MPa.

24. The method according to claim 23, wherein: The pressure of the gasifying agent is 6-8 MPa.

25. The method according to claim 10, wherein: The mass ratio of the fuel to the gasifying agent is 500:0.5-2.

26. The method according to claim 25, wherein: The mass ratio of the fuel to the gasifying agent is 500:0.9-1.

1.

27. The method according to claim 10, wherein: The plasma arc temperature in the plasma ignition device is 2000-7000K.

28. The method according to claim 27, wherein: The plasma arc temperature in the plasma ignition device is 3000-6000K.

29. The method according to claim 10, wherein: During the combustion, the mass ratio of the mixture to the secondary air is 100:20-30.

30. The method of claim 29, wherein: During the combustion, the mass ratio of the mixture to the secondary air is 100:5-20.

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