High-alkali coal furnace device for power station boiler combustion

Abstract

The invention discloses a high-alkali coal furnace device for power station boiler combustion, and belongs to the technical field of boiler transformation. At least four combustion chambers are arranged on the outer wall of the upper end of a hearth of the molten slag discharging boiler in a central symmetry mode, each combustion chamber is provided with two columns and four rows of cyclone combustors, each cyclone combustor is sequentially sleeved with an outer secondary air pipe, an inner secondary air pipe, a primary air pipe and a central air pipe from outside to inside, and a throat structure is arranged on the inner side of the primary air pipe. An axial rotational flow generator is arranged in the inner secondary air pipe, and a tangential rotational flow generator is arranged in the outer secondary air pipe. Air is divided into direct-flow center air, direct-flow primary air, rotational-flow inner secondary air and rotational-flow outer secondary air to be fed into the combustion chamber through the rotational-flow combustor, so that pulverized coal airflow firstly moves downwards and then turns to move upwards, and the movement stroke of pulverized coal particles in a high-temperature area in the furnace is prolonged; the flame center height and the combustion stability of pulverized coal airflow in the hearth of the liquid-state deslagging boiler are controlled, and the heat conduction efficiency of the hearth of the liquid-state deslagging boiler is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of boiler transformation, and in particular relates to a high-alkali coal-fired furnace device for a power station boiler. Background Art

[0002] Thermal power generation, which is mainly coal-fired power generation, still occupies a dominant position in my country's primary energy structure. my country's eastern and northern Xinjiang regions have rich high-alkali coal reserves and resources, which have great development and utilization value. And with the proposal of my country's dual carbon goals, the transformation of the boiler furnace structure will still help to achieve carbon peak as soon as possible. However, when the alkali metal salt content in the ash of high-alkali coal is high, the melting point of the ash will be reduced, and the ash will easily adhere to the high-temperature furnace wall in a molten or semi-molten state to form an initial slag layer and continuously absorb other ash particles to grow. Therefore, the direct use of high-alkali coal in ordinary boilers will cause serious ash accumulation and slagging problems on the heating surface, and even cause the heating surface to overheat and burst, affecting the normal operation of the boiler, which seriously hinders the promotion and application of high-alkali coal as a fuel for power station boilers. As an efficient liquid slag boiler, the double U-flame liquid slag boiler has the characteristics of high volumetric heat load and small size, and can effectively burn high-alkali coal. The electricity produced by the power plant must always be balanced with the user's consumption in terms of power and energy, which requires the boiler to be able to operate stably for a long time and have a certain load regulation capability. At the same time, it has higher thermal efficiency.

[0003] Traditional high-alkali coal-fired boilers mainly rely on on-site observations of high-alkali coal slagging, contamination and ash blockage to optimize the combustion of high-alkali coal. There are problems such as large delays and serious lags in regulation and control, which are not conducive to the safe and continuous combustion of high-alkali coal. At present, the types of boilers burning high-alkali coal usually include four-corner cut-circle coal-fired boilers with liquid slag discharge and double U-shaped liquid slag discharge boilers. The coal powder combustion area of ​​the double U-shaped flame boiler is mainly concentrated in the lower furnace, and the lower furnace is equipped with a fire-protection belt to prevent the flame temperature from decreasing. Therefore, the temperature of the lower furnace is higher than that of the traditional four-corner cut-circle boiler, which will lead to thermal NO x The amount of generated increases, and the possibility of slagging in the lower furnace increases. And it is unstable during variable load operation. Therefore, it is very necessary to reasonably transform the furnace of the double U-flame liquid slagging boiler, increase the boiler capacity and its heat load, and then improve the boiler production efficiency, which can provide ideas for the optimization and transformation of the liquid slagging furnace in the future.

[0004] To this end, the present invention provides a high-alkali coal-fired furnace device for a power station boiler based on the transformation of a liquid slag boiler furnace type. On the basis of fully considering the limited load variation range of traditional four-corner cut liquid slag boilers and double U-shaped liquid slag boilers, the requirements for the liquid slag boiler of the power station under conditions such as equipment foundation and load changes are further clarified, thereby ensuring the scientific rationality and practical guidance significance of the stable operation of the boiler under different loads. Summary of the invention

[0005] The purpose of the present invention is to propose a high-alkali coal-fired furnace device for power station boilers. Taking into full consideration that thermal power plants mainly burning high-alkali coal need a reasonable liquid slag discharge furnace and need to meet the load changes during boiler operation, the present invention proposes an optimization strategy of changing the furnace type, arranging four burners and combustion chambers on the left and right sides of the boiler and the front and rear walls; it is used to increase the boiler load and increase the boiler capacity so that the pulverized coal can be fully burned and meet the needs of variable load operation of power station boilers. At the same time, the burner structure is improved to achieve low-nitrogen combustion. It solves the problem that ordinary boilers burning high-alkali coal will cause serious ash and slagging on the heating surface, and even cause the heating surface to overheat and burst, affecting the normal operation of the boiler, and promotes the promotion and application of high-alkali coal as a fuel for power station boilers.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] The present invention provides a high-alkali coal-fired furnace device for a power station boiler, wherein at least four combustion chambers are symmetrically arranged at the center of the upper outer wall of the liquid slag discharge boiler furnace, and 2 rows and 4 rows of swirl burners are arranged on the top of each combustion chamber along the width direction of the combustion chamber, and the swirl burners include an outer secondary air duct, an inner secondary air duct, a primary air duct and a central air duct which are sequentially sleeved from the outside to the inside, and the outer secondary air duct, the inner secondary air duct, the primary air duct and the central air duct are all connected to the pre-pyrolysis chamber, a throat structure is arranged on the inner side of the primary air duct, an axial swirl generator is arranged in the inner secondary air duct, and a tangential swirl generator is arranged in the outer secondary air duct;

[0008] The swirl burner divides the incoming air into DC central air, DC primary air, secondary air inside the swirl and secondary air outside the swirl, and sends them into the combustion chamber, so that the coal powder airflow moves downward first and then turns and moves upward, extending the movement range of the coal powder particles in the high-temperature zone in the furnace, controlling the flame center height and combustion stability of the coal powder airflow in the furnace of the liquid slag discharge boiler, and improving the heat conduction efficiency of the furnace of the liquid slag discharge boiler.

[0009] Furthermore, for the above-mentioned power station boiler burning high-alkali coal furnace device, what is the relationship between the lengths of the swirl outer secondary air duct, the swirl inner secondary air duct, the primary air duct and the central air duct, and what is the relationship between their diameters.

[0010] Furthermore, in the above-mentioned power station boiler burning high-alkali coal furnace device, the throat structure includes a straight pipe and two first conical tubes, the diameter of the straight pipe is smaller than the diameter of the primary air duct, both ends of the straight pipe are connected to a first conical tube, and the other end of the first conical tube is connected to the primary air duct; along the axial direction of the primary air duct, the angle between the side wall of the first conical tube and the horizontal line of the primary air duct is 40°.

[0011] Furthermore, in the above-mentioned power station boiler burning high-alkali coal furnace device, the inner secondary air duct includes an inner secondary first air duct, an inner secondary second air duct and a second conical tube, the diameter of the inner secondary second air duct is larger than the diameter of the inner secondary first air duct, one end of the inner secondary first air duct is connected to the pre-pyrolysis chamber, and the other end is connected to one end of the second conical tube, and the other end of the second conical tube is connected to one end of the inner secondary first air duct; along the axial direction of the primary air duct, the angle between the side wall of the second conical tube and the horizontal line of the inner secondary air duct is 40°.

[0012] Furthermore, in the above-mentioned power station boiler burning high-alkali coal furnace device, the central air duct includes a central straight air duct and an arc tube, one end of the central straight air duct is connected to the pre-pyrolysis chamber, and the other end is connected to the arc tube, the pipe mouth of the arc tube faces downward, and the outer wall of the connecting end of the central straight air duct and the arc tube is provided with combustion stabilizing teeth.

[0013] Furthermore, in the above-mentioned power station boiler burning high-alkali coal furnace device, the axial swirl generator includes an axial swirl shaft, a swirl disk and a plurality of arc-shaped swirl blades, the axial swirl shaft is rotatably arranged in the inner secondary air duct, the swirl disk is arranged in the inner secondary air duct, all the arc-shaped swirl blades are rotatably arranged in the swirl disk, and all the arc-shaped swirl blades are connected to the axial swirl shaft.

[0014] Furthermore, in the above-mentioned power station boiler burning high-alkali coal furnace device, the tangential swirl generator includes a tangential swirl shaft, a tangential swirl disk and a plurality of arc-shaped tangential blades, the tangential swirl shaft is rotatably arranged in the outer secondary air duct, the tangential swirl disk is arranged in the outer secondary air duct, all the tangential blades are rotatably arranged in the tangential swirl shaft, and all the tangential blades are connected to the tangential swirl shaft.

[0015] Furthermore, in the above-mentioned power station boiler burning high-alkali coal furnace device, an impeller-type damper baffle is tangentially provided on the secondary air duct outside the swirl.

[0016] Furthermore, the above-mentioned power station boiler uses a high-alkali coal furnace device and a pre-pyrolysis chamber.

[0017] Furthermore, the above-mentioned power station boiler uses a high-alkali coal-fired furnace device, and the liquid slag discharge boiler furnace includes a cooling chamber, and the combustion chamber is centrally symmetrically arranged on a centrally symmetrical outer wall. The cooling chamber is provided with a slag catching pipe, and the slag catching pipe is located at the lower part of the cooling chamber. The combustion chamber is also provided with an ash hopper, and the ash hopper is located above the swirl burner.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention fully considers that thermal power plants mainly burning high-alkali coal need a reasonable liquid slag discharge furnace and need to meet the load changes during boiler operation. It proposes an optimization strategy for changing the furnace type and arranging four burners and combustion chambers on the left and right sides of the boiler and the front and rear walls. It is used to increase the boiler load and increase the boiler capacity so that the coal powder can be fully burned and meet the needs of variable load operation of power station boilers. At the same time, the burner structure is improved to achieve low-nitrogen combustion. It solves the problem that ordinary boilers burning high-alkali coal will cause serious ash and slagging on the heating surface, and even cause the heating surface to overheat and burst, affecting the normal operation of the boiler, and promotes the promotion and application of high-alkali coal as a fuel for power station boilers.

[0020] 2. The burner provided in the present invention enables the coal powder airflow to move downward first and then turn upward, thereby extending the movement distance of the coal powder particles in the high temperature zone in the furnace and increasing the residence time of the coal powder particles in the high temperature zone, which can significantly improve the ignition and burnout of low-volatile coal.

[0021] 3. In the boiler furnace proposed by the present invention, a small amount of secondary air enters the furnace from the arch along with the primary air, and most of the secondary air is delivered from the bottom of the arch in a graded air supply manner, thereby reducing the air volume in the main combustion zone and allowing the pulverized coal airflow to absorb more heat from the high-temperature reflux flue gas to increase its own temperature, thereby increasing the combustion stability of the flame.

[0022] 4. The liquid slag removal furnace proposed by the present invention can realize an efficient combustion process. By optimizing the combustion parameters, the thermal efficiency of the boiler can be improved, the fuel consumption can be reduced, and thus the energy consumption and operating costs can be reduced.

[0023] 5. The traditional liquid slag furnace has limited boiler capacity due to structural limitations, but the boiler proposed in the present invention can effectively increase the boiler capacity. By optimizing the combustion chamber structure and cooling system, the heat generated by combustion can be fully utilized, the heat conduction efficiency of the boiler can be improved, and the boiler capacity can be expanded.

[0024] 6. The boiler proposed by the present invention can adapt to changes in demand. With the changes in industrial production demand, a boiler system that can be flexibly adjusted is needed. By adjusting the boiler load, it can better adapt to changes in production demand and meet the heat supply demand under different load conditions.

[0025] 7. In the present invention, along the axial direction of the primary air duct, the angle between the side wall of the first truncated cone tube and the horizontal line of the primary air duct is 40°, and the angle between the side wall of the second truncated cone tube and the horizontal line of the inner secondary air duct is 40°. Smaller primary air and inner secondary air expansion cone angles and outer secondary air area are used to improve the rigidity of the outer secondary air, which can delay the mixing of the primary air and the secondary air, thereby reducing the NOx emission level and alleviating the coking problem of the water-cooled wall.

[0026] 6. The inner-concentrated and outer-lean coal powder separation device of the present invention can directly heat the concentrated coal powder by central reflux heating, thereby increasing the ignition point concentration and the ignition point coal powder temperature, thereby advancing the ignition of the coal powder in the low-nitrogen combustion mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of a high-alkali coal-fired furnace device for a power station boiler of the present invention;

[0028] Figure 2 It is a side view structural schematic diagram of a high-alkali coal-fired furnace device for a power station boiler of the present invention;

[0029] Figure 3 It is a top view of the structure of the high-alkali coal-fired furnace device of the power station boiler of the present invention;

[0030] Figure 4 It is a structural schematic diagram of the combustion chamber of the present invention;

[0031] Figure 5 It is a structural schematic diagram of the burner of the present invention;

[0032] Figure 6 It is a schematic diagram of the structure of the axial swirl generator and the tangential swirl generator of the present invention;

[0033] Description of reference numerals:

[0034] 1. Cooling chamber, 2. Combustion chamber, 3. Swirl burner, 31. External secondary air duct, 32. Internal secondary air duct, 321. Internal secondary first air duct, 322. Internal secondary second air duct, 323. Second truncated cone tube, 33. Primary air duct, 331. Throat structure, 3311. Straight tube, 3312. First truncated cone tube, 34. Central air duct, 341. Central straight air duct, 342. Arc tube, 4. Slag catching tube, 5. Ash hopper, 6. Axial swirl generator, 61. Axial swirl shaft, 62. Swirl disk, 63. Arc swirl blade, 7. Tangential swirl generator, 71. Tangential swirl shaft, 72. Tangential swirl disk, 73. Tangential blade. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand that the technical solution of the present invention can be implemented, the present invention is further described below in conjunction with specific embodiments and drawings. The described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0036] The pulverized coal combustion area of ​​the double U-flame boiler is mainly concentrated in the lower furnace, and the lower furnace is equipped with a fire-protection belt to prevent the flame temperature from decreasing. Therefore, the temperature of the lower furnace is higher than that of the traditional four-corner tangential boiler, which will lead to thermal NO x The amount of generated increases, and the possibility of slagging in the lower furnace is increased. And it is unstable during variable load operation, and the application number 202011146537.3 discloses a stepless peak-shaving coupled pyrolysis burner and combustion system, wherein the burner includes a pre-pyrolysis chamber, an outer secondary air duct, an inner secondary air swirl blade, an inner secondary air duct, a primary air duct and a central air duct, and the pyrolysis process of the pulverized coal in the pre-pyrolysis chamber is controlled by the burner to adapt to the low-load stable ignition of different types of coal; solve the problem of stable combustion of pulverized coal when the power station boiler is running at low load, and enhance the deep peak-shaving capacity of the thermal power unit to a greater extent. However, the pulverized coal concentration separation structure set in the primary air duct forms an inner thin and outer thick structure, which is not conducive to the ignition and burnout of pulverized coal in the low-nitrogen combustion mode, that is, it is easy to produce hypoxia at the ignition point, and the angles of the primary air duct and the inner secondary air duct are easy to cause thermal deformation, and even cause the heating surface to overheat and burst, and the heat conduction efficiency of the boiler is reduced, affecting the normal operation of the boiler.

[0037] Based on this, the present invention provides a power station boiler burning high-alkali coal furnace device, such as Figure 1-5As shown, at least four combustion chambers 2 are symmetrically arranged on the center of the outer wall of the upper end of the furnace 1 of the liquid slag discharge boiler. Two rows and four lines of swirl burners 3 are arranged on the top of each combustion chamber 2 along the width direction of the combustion chamber 2. The boiler structure is a symmetrical arrangement of the burners, and one combustion chamber is arranged on both sides and in front and behind the intermediate cooling chamber. The primary air and secondary air carrying coal powder are vertically shot down in the combustion chamber and ignite. The high-temperature flue gas flowing out of the combustion chamber flows through the slag catching pipe and enters the cooling chamber to continue to release heat. The height of the combustion chamber (to the bottom of the ash hopper) is 13.734m, the height of the cooling chamber is 41.314m, the width of the furnace is 14.706m, the depth of the combustion chamber is 5.700m, the depth of the lower part of the cooling chamber is 7.300m, and the depth of the upper part of the cooling chamber is 13.506m. There are 2 rows and 4 lines of swirl burners arranged above the combustion chambers on all four sides of the boiler, with a total of 16 burners. Burner 3 adopts a coal powder distribution with a concentrated inner layer and a light outer layer, a central reflux heating, and an outer ring ignition combustion organization form. Compared with the power process produced by the double U-type liquid slag discharge boiler power plant, which has a high tensile volume heat load and a small size, and cannot meet the long-term stable operation and has a certain load regulation capability, the present invention fully considers that the thermal power plant mainly burning high-alkali coal needs a reasonable liquid slag discharge furnace and needs to meet the load changes during boiler operation. On the basis of the process, it proposes an optimization strategy of changing the furnace type and installing burners on the front and back walls respectively; it is used to increase the boiler load and increase the boiler capacity so that the coal powder is fully burned and meet the needs of variable load operation of the power station boiler, so that the coal powder airflow moves downward first and then turns upward, extending the movement of the coal powder particles in the high temperature zone of the furnace, and increasing the residence time of the coal powder particles in the high temperature zone, which can significantly improve the ignition and burnout of low-volatile coal. Without changing the burner layout elevation and position or adding new burners, the ignition of coal is enhanced and brought forward, thereby controlling the center height of the furnace flame and strengthening the burnout of pulverized coal, thereby ensuring low-nitrogen combustion and controlling the carbon content of fly ash and large slag and the amount of cooling water.

[0038] The swirl burner 3 comprises an outer secondary air duct 31, an inner secondary air duct 32, a primary air duct 33 and a central air duct 34 which are sequentially sleeved from the outside to the inside, the outer secondary air duct 31, the inner secondary air duct 32, the primary air duct 33 and the central air duct 34 are all connected to the pre-pyrolysis chamber 35, a throat structure 331 is provided on the inner side of the primary air duct 33, an axial swirl generator 6 is provided in the inner secondary air duct 32, and a tangential swirl generator 7 is provided in the outer secondary air duct 31; the swirl burner 3 divides the introduced air into direct current central air, direct current primary air, swirl inner secondary air and swirl outer secondary air and sends them into the combustion chamber 2, so that the pulverized coal airflow moves downward first and then turns to move upward, thereby extending the movement stroke of the pulverized coal particles in the high temperature zone in the furnace, controlling the flame center height and combustion stability of the pulverized coal airflow in the furnace 1 of the liquid slag discharge boiler, and improving the heat conduction efficiency of the furnace 1 of the liquid slag discharge boiler. Burner 3 adopts a combustion organization form of inner-thick and outer-thin coal powder distribution, central reflux heating, and outer ring ignition. After the coal powder passes through the primary air duct, it forms an inner-thick and outer-thin stratification. The central reflux heating can directly heat the thick side coal powder, which can increase the ignition point concentration while increasing the ignition point coal powder temperature, and realize the early ignition of coal powder in the low-nitrogen combustion mode (ignition point lack of oxygen). In order to prevent the wear of the parts in contact with the coal powder in the burner, all ceramic sheets are used for anti-wear in the low-temperature area far from the nozzle. The ceramic sheets are not only bonded to the parts by high-temperature glue, but also fixed to the parts by fixed cone welding to prevent the ceramic sheets from falling off; in the high-temperature area close to the nozzle, all parts are made of high-temperature and wear-resistant high-chromium and high-nickel cast alloy steel, and the material is ZG 40 Cr 26 Ni 16 Si2NRe. At the same time, the primary air and inner secondary air expansion cone angles are set to 40°, reducing the outer secondary air area and improving the rigidity of the outer secondary air. In order to prevent thermal deformation, the secondary air expansion cone is integrally cast with high-temperature resistant high-nickel alloy steel. The material is ZG 40 Cr 25 Ni 20 The external secondary air expansion cone is made of high-temperature plastic corundum on-site. A combustion stabilizing tooth is set at the front end of the central air duct to enhance the combustion stabilizing performance of the burner. In order to prevent the central tube support from abrasion and causing the central tube to deviate, an integral ceramic wrap is set on the windward side of the central air duct support.

[0039] The invention is further described below through specific examples.

[0040] A power station boiler burning high-alkali coal furnace device, such as Figure 1-5As shown, at least four combustion chambers 2 are symmetrically arranged on the center of the outer wall of the upper end of the furnace 1 of the liquid slag discharge boiler. Two rows and four lines of swirl burners 3 are arranged on the top of each combustion chamber 2 along the width direction of the combustion chamber 2. The boiler structure is a symmetrical arrangement of the burners, and one combustion chamber is arranged on both sides and in front and behind the intermediate cooling chamber. The swirl burner 3 includes an outer secondary air duct 31, an inner secondary air duct 32, a primary air duct 33 and a central air duct 34 which are sequentially sleeved from the outside to the inside. The outer secondary air duct 31, the inner secondary air duct 32, the primary air duct 33 and the central air duct 34 are all connected to the pre-pyrolysis chamber 35. A throat structure 331 is provided on the inner side of the primary air duct 33. An axial swirl generator 6 is provided in the inner secondary air duct 32. A tangential swirl generator 7 is provided in the outer secondary air duct 31. The diameter of the central air duct 34 is 200mm and the length is 4172mm. The diameter of the primary air duct 33 is 665-740mm. The length is 3617mm, the diameter of the inner secondary air duct 32 is 710-1200mm, the length is 2647mm, the diameter of the outer secondary air duct 31 is 1770mm, and the length is 772mm; the swirl burner 3 divides the incoming air into DC central air, DC primary air, swirl inner secondary air and swirl outer secondary air, and sends them into the combustion chamber 2, so that the coal powder airflow moves downward first and then turns upward, extending the movement range of the coal powder particles in the high temperature zone in the furnace, controlling the flame center height and combustion stability of the coal powder airflow in the liquid slag discharge boiler furnace 1, and improving the heat conduction efficiency of the liquid slag discharge boiler furnace 1.

[0041] The throat structure 331 includes a straight tube 3311 and two first truncated cone tubes 3312. The diameter of the straight tube 3311 is smaller than the diameter of the primary air duct 33. Both ends of the straight tube 3311 are connected to a first truncated cone tube 3312, and the other end of the first truncated cone tube 3312 is connected to the primary air duct 33. Along the axial direction of the primary air duct 33, the angle between the side wall of the first truncated cone tube 3312 and the horizontal line of the primary air duct 33 is 40°. The side wall water-cooled wall in the main burner area of ​​the furnace is severely corroded by high-temperature sulfur, and there is coking. The average coking of the water-cooled wall in the burner area is 100-200 mm, and the bottom of the screen superheater is seriously coked, with the largest coke block being about 1 ton. The main reasons are: the original burner design has an unreasonable expansion cone angle of the inner and outer secondary air nozzles, that is, the angle between the side wall of the first conical tube 3312 and the horizontal line of the primary air duct 33, which delays ignition. In the low-nitrogen mode, the rotational momentum of the inner and outer secondary air decreases and diffuses too quickly, causing the coal powder particles to be thrown to the walls around the burner and burn; at the same time, the outer secondary air area is reduced and the rigidity of the outer secondary air is increased.

[0042] In a specific embodiment, the present invention arranges a throat structure inside the primary air duct 33, and the pulverized coal forms inner-concentrated and outer-lightened stratification after passing through the throat structure. Therefore, the central reflux heating can directly heat the concentrated side pulverized coal, and while increasing the ignition point concentration, it can also increase the ignition point pulverized coal temperature, and achieve early ignition of the pulverized coal in the low nitrogen combustion mode (ignition point lack of oxygen).

[0043] In a specific embodiment, the inner secondary air duct 32 includes an inner secondary first air duct 321, an inner secondary second air duct 322 and a second truncated cone tube 323. The diameter of the inner secondary second air duct 322 is greater than the diameter of the inner secondary first air duct 321. One end of the inner secondary first air duct 321 is connected to the pre-pyrolysis chamber 35, and the other end is connected to one end of the second truncated cone tube 323. The other end of the second truncated cone tube 323 is connected to one end of the inner secondary first air duct 321. Along the axial direction of the primary air duct 33, the angle between the side wall of the second truncated cone tube 321 and the horizontal line of the inner secondary air duct 32 is 40°. The primary air and the secondary air are essentially for providing oxygen for coal powder combustion. The position of the diffusion cone can be extended or retracted to adjust the outlet velocity of the primary air and the size of the airflow diffusion angle. When burning low-volatile coal, it is customary to increase the cone angle of the diffusion cone, that is, the angle between the side wall of the second conical tube 321 and the horizontal line of the inner secondary air duct 32 is increased to increase the reflux of high-temperature flue gas, but at the same time it also increases the probability of coal powder particles colliding with the surface of the diffusion cone. The coal powder particles that lose kinetic energy after the collision will be separated from the gas-powder flow and fall into the cold ash hopper of the boiler before being completely burned, resulting in incomplete combustion losses.

[0044] In a specific embodiment, the central air duct 34 includes a central straight air duct 341 and an arc tube 342. One end of the central straight air duct 341 is connected to the pre-pyrolysis chamber 35, and the other end is connected to the arc tube 342. The mouth of the arc tube 342 faces downward, and the outer wall of the connecting end of the central straight air duct 341 and the arc tube 342 is provided with a combustion stabilizing tooth 343. The primary air inlet is an arc tube 342, which can utilize the inlet effect and generate secondary circulation due to the centrifugal force in the curved section of the arc tube to increase disturbance, which is conducive to sufficient mixing with coal powder; the stabilizing teeth 343 are composed of a circle of small teeth (or an additional ring), and its purpose is to form many small vortices on the back flow surface of the teeth to stabilize the ignition of the coal powder airflow. The recirculation zone formed by the stabilizing teeth 343 attached to the outside of the primary air powder airflow is in the annular area between the primary and secondary air. The temperature of the recirculation zone is not high. It is difficult to stabilize the ignition and combustion of coal powder relying solely on this recirculation zone, but it has the effect of properly preventing the primary and secondary air from mixing too early and blocking the tendency of coal powder (especially coarse coal powder) to diffuse into the secondary air. It can also allow an appropriate amount of coal powder particles to enter the high-temperature internal recirculation zone, which has a certain effect on the stabilization of coal powder combustion; the stabilizing teeth 343-shaped stabilizer attached to the inner side of the primary air helps the reflux of high-temperature flue gas, which has a certain effect on the ignition and combustion of the coal powder airflow.

[0045] In a specific embodiment, the axial swirl generator 6 includes an axial swirl shaft 61, a swirl disk 62 and a plurality of arc swirl blades 63, wherein the axial swirl shaft 61 is rotatably arranged in the inner secondary air duct 32, the swirl disk 62 is arranged in the inner secondary air duct 32, all the arc swirl blades 63 are rotatably arranged in the swirl disk 62, and all the arc swirl blades 63 are connected to the axial swirl shaft 61. When the pulverized coal airflow passes through the axial swirl generator 6, the swirl shaft 61 rotates to form a rotating jet of the arc swirl blades 63 on the swirl disk 62. The rotating jet can form a high-temperature flue gas recirculation zone that is conducive to ignition and make the airflow strongly mixed. After ejecting the nozzle, a recirculation zone is formed in the center of the airflow, and this recirculation zone is called the inner recirculation zone. The inner recirculation zone draws the high-temperature flue gas in the furnace to heat the pulverized coal airflow. When the pulverized coal airflow has a certain amount of heat and reaches the ignition temperature, it starts to ignite, and the flame spreads outward from the inner edge of the inner recirculation zone.

[0046] In a specific embodiment, the tangential swirl generator 7 includes a tangential swirl shaft 71, a tangential swirl disk 72 and a plurality of arc-shaped tangential blades 73. The tangential swirl shaft 71 is rotatably arranged in the outer secondary air duct 31, the tangential swirl disk 72 is arranged in the outer secondary air duct 31, all the tangential blades 73 are rotatably arranged in the tangential swirl shaft 71, and all the tangential blades 73 are connected to the tangential swirl shaft 71. After the coal powder airflow in the outer secondary air duct 31 enters the tangential swirler 7, the swirl shaft 71 rotates to make the arc-shaped tangential blades 73 on the tangential swirl disk 72 form a tangential rotating jet, and the secondary air forms a rotating airflow, from

[0047] In a specific embodiment, an impeller-type damper is tangentially arranged on the swirl external secondary air duct 31. The purpose of the impeller-type damper is to rotate the airflow.

[0048] In a specific embodiment, the pre-pyrolysis chamber 35 includes a pre-pyrolysis chamber inner cavity 351, and the outer secondary air duct 31 is arranged circumferentially around the pre-pyrolysis chamber inner cavity 351. The purpose of the pre-pyrolysis chamber 35 is to mix coal powder and air for combustion.

[0049] In a specific embodiment, the liquid slag discharge boiler furnace 1 includes a cooling chamber 5, the combustion chamber 2 is centrally symmetrically arranged on a centrally symmetrical outer wall, the cooling chamber 5 is provided with a slag catching pipe 6, and the slag catching pipe 6 is located at the lower part of the cooling chamber 5, that is, the slag catching pipe 6 is located at the lower part of the cooling chamber 5, that is, between the combustion zone and the heat transfer zone, and the combustion chamber 2 is also provided with an ash hopper 7, and the ash hopper 7 is located above the swirl burner 3.

[0050] The burner 2 allows the coal powder airflow to pass through the swirl burner 3. The swirl burner 3 is sequentially sleeved with an outer secondary air duct 31, an inner secondary air duct 32, a primary air duct 33 and a central air duct 34 from the outside to the inside, and the air introduced is divided into a DC central air, a DC primary air, a swirl inner secondary air and a swirl outer secondary air, and is sent into the combustion chamber of the burner 2, so that the coal powder airflow moves downward first and then turns and moves upward, extending the movement stroke of the coal powder particles in the high-temperature zone in the furnace, controlling the flame center height and combustion stability of the coal powder airflow in the furnace 1 of the liquid slag discharge boiler, and improving the heat conduction efficiency of the furnace 1 of the liquid slag discharge boiler. A small amount of secondary air in the boiler furnace 1 enters the furnace 1 from the arch along with the primary air, and most of the secondary air is sent from the bottom of the arch in a graded air supply manner, thereby reducing the air volume in the main combustion zone and allowing the coal powder airflow to flow back from the high temperature zone. The flue gas absorbs more heat to increase its own temperature, thereby increasing the combustion stability of the flame; when the pulverized coal airflow and wind pass through the pre-pyrolysis chamber 35 for mixed combustion, when the pulverized coal airflow passes through the axial swirl generator 6, a rotating jet is used to form a high-temperature flue gas recirculation zone that is conducive to ignition, and the airflow is strongly mixed; after the pulverized coal airflow in the outer secondary air duct 31 enters the tangential swirler 7, a tangential rotating jet is formed, and the secondary wind forms a rotating airflow, and the burner 3 adopts a combustion organization form of inner-thick and outer-thin pulverized coal distribution, central reflux heating, and outer ring ignition. After the pulverized coal passes through the primary air duct, an inner-thick and outer-thin stratification is formed, and the central reflux heating can directly heat the pulverized coal on the thick side, which can increase the ignition point concentration while increasing the ignition point pulverized coal temperature, thereby achieving early ignition of the pulverized coal in the low nitrogen combustion mode (ignition point lack of oxygen). The present invention fully considers that thermal power plants mainly burning high-alkali coal need a reasonable liquid slag discharge furnace and need to meet the load changes during boiler operation. It proposes an optimization strategy of changing the furnace type, arranging four burners and combustion chambers on the left and right sides of the boiler and the front and rear walls; it is used to increase the boiler load and increase the boiler capacity so that the coal powder is fully burned and meet the needs of variable load operation of power station boilers. At the same time, the burner structure is improved to achieve low-nitrogen combustion. It solves the problem that ordinary boilers burning high-alkali coal will cause serious ash and slagging on the heating surface, and even cause the heating surface to overheat and burst, affecting the normal operation of the boiler, and promotes the promotion and application of high-alkali coal as a fuel for power station boilers.

[0051] It should be noted that the component connection relationships not specifically mentioned in the present invention are assumed to adopt the existing technology. Since they do not involve the invention point and are widely used in the existing technology, the structural connection relationships are not described in detail.

[0052] It should be noted that when the present invention involves a numerical range, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0053] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A power station boiler burning high-alkali coal furnace device, including a liquid slag discharge boiler furnace, characterized in that: At least four combustion chambers (2) are symmetrically arranged at the center of the upper outer wall of the furnace of the liquid slag discharge boiler, and two rows and four lines of swirl burners (3) are arranged at the top of each combustion chamber (2) along the width direction of the combustion chamber (2), the swirl burners (3) comprising an outer secondary air duct (31), an inner secondary air duct (32), a primary air duct (33) and a central air duct (34) which are sequentially sleeved from the outside to the inside, the outer secondary air duct (31), the inner secondary air duct (32), the primary air duct (33) and the central air duct (34) are all connected to the pre-pyrolysis chamber (35), a throat structure (331) is arranged on the inner side of the primary air duct (33), an axial swirl generator (6) is arranged in the inner secondary air duct (32), and a tangential swirl generator (7) is arranged in the outer secondary air duct (31); The swirl burner (3) divides the air introduced into direct current central air, direct current primary air, secondary air inside the swirl and secondary air outside the swirl and delivers them into the combustion chamber (2), so that the coal powder airflow first moves downward and then turns to move upward, thereby extending the movement range of the coal powder particles in the high-temperature zone in the furnace, controlling the flame center height and combustion stability of the coal powder airflow in the furnace (1) of the liquid slag discharge boiler, and improving the heat conduction efficiency of the furnace (1) of the liquid slag discharge boiler.

2. The power station boiler burning high-alkali coal furnace device according to claim 1, characterized in that: The throat structure (331) comprises a straight tube (3311) and two first truncated cone tubes (3312); the diameter of the straight tube (3311) is smaller than the diameter of the primary air duct (33); both ends of the straight tube (3311) are connected to a first truncated cone tube (3312); the other end of the first truncated cone tube (3312) is connected to the primary air duct (33); along the axial direction of the primary air duct (33), the angle between the side wall of the first truncated cone tube (3312) and the horizontal line of the primary air duct (33) is 40°.

3. The power station boiler burning high-alkali coal furnace device according to claim 1, characterized in that: The inner secondary air duct (32) comprises an inner secondary first air duct (321), an inner secondary second air duct (322) and a second truncated cone tube (323); the diameter of the inner secondary second air duct (322) is greater than the diameter of the inner secondary first air duct (321); one end of the inner secondary first air duct (321) is connected to the pre-pyrolysis chamber (35), and the other end is connected to one end of the second truncated cone tube (323); the other end of the second truncated cone tube (323) is connected to one end of the inner secondary first air duct (321); along the axial direction of the primary air duct (33), the angle between the side wall of the second truncated cone tube (323) and the horizontal line of the inner secondary air duct (32) is 40°.

4. The power station boiler burning high-alkali coal furnace device according to claim 1, characterized in that: The central air duct (34) comprises a central straight air duct (341) and an arc-shaped tube (342); one end of the central straight air duct (341) is connected to the pre-pyrolysis chamber (35), and the other end is connected to the arc-shaped tube (342); the tube mouth of the arc-shaped tube (342) faces downward, and the outer wall of the connecting end of the central straight air duct (341) and the arc-shaped tube (342) is provided with a combustion stabilizing tooth (343).

5. The power station boiler burning high-alkali coal furnace device according to claim 1, characterized in that: The axial swirl generator (6) comprises an axial swirl shaft (61), a swirl disk (62) and a plurality of arc-shaped swirl blades (63); the axial swirl shaft (61) is rotatably disposed in the inner secondary air duct (32); the swirl disk (62) is disposed in the inner secondary air duct (32); all the arc-shaped swirl blades (63) are rotatably disposed in the swirl disk (62), and all the arc-shaped swirl blades (63) are connected to the axial swirl shaft (61).

6. The power station boiler burning high-alkali coal furnace device according to claim 1, characterized in that: The tangential swirl generator (7) comprises a tangential swirl shaft (71), a tangential swirl disk (72) and a plurality of arc-shaped tangential blades (73); the tangential swirl shaft (71) is rotatably disposed in an outer secondary air duct (31); the tangential swirl disk (72) is disposed in the outer secondary air duct (31); all of the tangential blades (73) are rotatably disposed in the tangential swirl shaft (71), and all of the tangential blades (73) are connected to the tangential swirl shaft (71).

7. The power station boiler burning high-alkali coal furnace device according to claim 1, characterized in that: An impeller-type damper plate is tangentially arranged on the swirl outer secondary air duct (31).

8. The power station boiler burning high-alkali coal furnace device according to claim 1, characterized in that: The central air duct (34) has a diameter of 200 mm and a length of 4172 mm, the primary air duct (33) has a diameter of 665-740 mm and a length of 3617 mm, the inner secondary air duct (32) has a diameter of 710-1200 mm and a length of 2647 mm, and the outer secondary air duct (31) has a diameter of 1770 mm and a length of 772 mm.

9. The power station boiler burning high-alkali coal furnace device according to claim 1, characterized in that: The pre-pyrolysis chamber (35) includes an inner cavity (351) of the pre-pyrolysis chamber, and the outer secondary air duct (31) is arranged around the inner cavity (351) of the pre-pyrolysis chamber in a circumferential direction.

10. The power station boiler burning high-alkali coal furnace device according to claim 1, characterized in that: The furnace of the liquid slag discharge boiler comprises a cooling chamber (1), the combustion chamber (2) is centrally symmetrically arranged on the outer wall of the cooling chamber (1), the cooling chamber (1) is provided with a slag catching pipe (4), the slag catching pipe (4) is located at the lower part of the cooling chamber (1), and the combustion chamber (2) is also provided with an ash hopper (5), and the ash hopper (5) is located above the swirl burner (3).

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