Anti-coking furnace of four-corner tangential combustion boiler

Abstract

The utility model provides a coking-proof furnace of a four-corner cut-circle combustion boiler, belonging to the field of boiler combustion equipment manufacturing; the utility model comprises: a chamber body; the lower inner part of the chamber body is a combustion area, and the upper inner part of the chamber body is a burnout wind area; multiple layers of coal powder injection areas are arranged from top to bottom in the combustion area; each layer of the coal powder injection area includes four coal powder injection ports that are centrally symmetrically arranged and located in the same plane; in each layer of the coal powder injection area, at least two of the coal powder injection ports are inclined. The utility model tilts the coal powder injection ports, thereby systematically concentrating the oxygen for part of the coal powder to burn out, while leaving enough space for part of the coal powder to be burned out in the burnout area, thereby greatly reducing and eliminating the coking problem caused by the collision and adhesion of unburned particles.

Description

Technical Field

[0001] The utility model relates to a coking prevention technology for a four-corner tangentially fired boiler, in particular to an anti-coking furnace for a four-corner tangentially fired boiler, and belongs to the technical field of boiler equipment manufacturing. Background Art

[0002] During the combustion of fuel, the generation of nitrogen oxides is part of the combustion reaction: the nitrogen oxides generated by combustion are mainly NO and NO2, collectively referred to as NOx. NOx in the atmosphere will dissolve in water and generate nitric acid rain. Acid rain will cause extensive harm to the environment, cause huge economic losses, and easily endanger human health.

[0003] The four-corner tangential combustion boiler has burners arranged at the four corners, usually with a layer of wind and a layer of coal, forming a wind-coated coal situation. The primary air-powder mixture is ejected from the four corners to the confined space of the furnace within a certain distance from the burner nozzle, and is directly impacted by the high-temperature hot air in the furnace, which has excellent ignition conditions and good ignition stability. The four-corner injection tangential circle, the primary air-powder power is strong and the tangential circle is small, and the secondary air power is weak and the tangential circle is large, forming a natural wind-coated coal combustion form, interacting with each other, strengthening the mixing with the secondary air, and at the same time, the ash shell on the surface of the coal powder particles during combustion is easily detached by impact, which accelerates the internal combustion of the coal powder particles and is conducive to the burnout of the coal powder. However, low-nitrogen combustion control is to burn the main combustion area with insufficient oxygen, use about 30% of the secondary air as the burnout air, control the oxygen content to control the combustion speed, reduce the combustion flame temperature, and achieve the control of nitrogen oxide generation. The burnout air is then used to form a new level of graded combustion, the purpose of which is to control the generation of nitrogen oxides without affecting the burnout of the fuel.

[0004] However, due to the lack of oxygen in the main combustion area, most of the coal powder particles are delayed in burning, which greatly reduces the secondary air and weakens the wind-coated coal capacity in the main combustion area of ​​the furnace. These unburned carbon particles originally collide with each other to shed the ash shell, which is beneficial for the combustion of particles. Under the lack of oxygen, the molten particles stop burning, and the particles become coarser when they collide with each other, just like a rolling snowball that keeps getting bigger. Under the centrifugal force of the four-corner tangent circle, the coarse particles adhere to the water-cooled wall surface to form coke, pass through the furnace outlet and enter the horizontal flue, and also form contamination and adhesion to the tail superheater, which weakens the heat absorption of the overall heating surface and increases the exhaust gas temperature. The contamination and coking of the furnace also affect the local water-cooled wall heat absorption, pushing up the flame temperature in this area. In addition, the lack of oxygen combustion is prone to reduce-type oxidized flue gas, generating a large amount of CO, resulting in high-temperature corrosion, oxidation peeling and thinning, and finally bursting. In addition, the carbon particles are enlarged by mutual collision and adhesion. Because the wind-coated coal is weakened, the coarse particles directly flush the surface of the water-cooled wall, resulting in thinning of the water-cooled wall tube wall and bursting.

[0005] In the process of burning Zhundong coal in the existing technology, in order to alleviate the coking in the furnace and protect the safety of boiler equipment, a certain proportion of kaolin is burned, which makes the composition of the flue gas emitted by the boiler combustion more complex. This is because kaolin may produce volatile organic compounds (VOCs) and other combustible pollutants during combustion. These wastes pollute the soil, air, and water sources, and are more harmful to the environment and human health.

[0006] Therefore, there is an urgent need for equipment and technology that does not require the addition of other raw materials, can effectively prevent furnace coking and can ensure low-nitrogen combustion. Utility Model Content

[0007] The utility model provides a novel anti-coking furnace of a four-corner tangential combustion boiler, which solves the technical problem of easy coking in the furnace in the prior art by tilting some coal powder injection ports on the same layer in the combustion area so that some coal powder is fully burned and enough floating space is left for the coal powder that is not fully burned.

[0008] The anti-coking furnace of the four-corner tangential combustion boiler of the utility model embodiment comprises: a furnace body; the lower part of the furnace body is a combustion area, and the upper part of the furnace body is a burnout air area;

[0009] Multiple layers of pulverized coal injection zones are arranged from top to bottom in the combustion zone; each layer of the pulverized coal injection zone includes four pulverized coal injection ports that are centrally symmetrically arranged and located in the same plane; in each layer of the pulverized coal injection zone, at least two of the pulverized coal injection ports are inclinedly arranged.

[0010] The anti-coking furnace of the four-corner tangential combustion boiler as described above, wherein multiple layers of overburnt air injection zones are arranged from top to bottom in the overburnt air zone;

[0011] Each layer of the burnout wind injection zone includes four burnout wind injection ports on the same plane; in each layer of the burnout wind injection zone, the injection trajectories of the four burnout wind injection ports are located on the circumference of the same inscribed circle, and the diameter of the inscribed circle is the inscribed circle airflow diameter; the inscribed circle airflow diameters of two adjacent burnout wind injection zones are different.

[0012] As described above, in the anti-coking furnace of the four-corner tangential circle combustion boiler, the diameter of the inscribed circle airflow in the multiple layers of the burnout air injection zone increases gradually from top to bottom.

[0013] As described above, in the anti-coking furnace of the four-corner tangential circle combustion boiler, the diameter of the inscribed circle airflow in the multiple layers of the burnout air injection zone gradually decreases from top to bottom.

[0014] As described above, in the anti-coking furnace of the four-corner tangential combustion boiler, in each layer of the pulverized coal injection area, the inclination angles of the two pulverized coal injection ports spaced apart from each other are the same, and the other two pulverized coal injection ports are located in the plane where the pulverized coal injection area of ​​the layer is located.

[0015] As described above, in the anti-coking furnace of the four-corner cut-circle combustion boiler, in each layer of the pulverized coal injection area, the inclination angles of the two pulverized coal injection ports spaced apart from each other are the same and are both inclined upward; the inclination angles of the other two pulverized coal injection ports are the same and are both inclined downward.

[0016] As described above, in the anti-coking furnace of the four-corner tangential combustion boiler, the inclination angle of each of the pulverized coal injection ports in each layer of the pulverized coal injection zone is adjustable.

[0017] In the anti-coking furnace of the four-corner tangential combustion boiler as described above, the inclination angle of the coal powder injection port is 8 to 15 degrees.

[0018] In the embodiment of the utility model, the coal powder injection port is tilted so that the oxygen is concentrated in a planned manner to supply part of the coal powder for combustion, while leaving enough space for part of the coal powder to be burned in the combustion area, which greatly reduces and eliminates the coking problem caused by the collision and adhesion of unburned particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the coal powder injection trajectory in the combustion area of ​​the anti-coking furnace of the four-corner tangential combustion boiler according to the embodiment of the utility model;

[0020] Figure 2 It is a schematic diagram of the coal powder injection trajectory in the combustion area of ​​the anti-coking furnace of a four-corner tangential combustion boiler according to another embodiment of the utility model;

[0021] Figure 3 A schematic diagram of the coal powder injection trajectory in the combustion area of ​​the anti-coking furnace of a four-corner tangential combustion boiler according to another embodiment of the utility model;

[0022] Figure 4 It is a schematic diagram of tangential airflow in the burnout air region of the anti-coking furnace of a four-corner tangential combustion boiler according to an embodiment of the utility model;

[0023] Figure 5 This is a schematic diagram of tangential airflow in the burnout air area of ​​the anti-coking furnace of a four-corner tangential combustion boiler according to another embodiment of the utility model. DETAILED DESCRIPTION

[0024] The anti-coking furnace of the four-corner tangential combustion boiler described in the utility model can be made of the following materials and components, but is not limited to the following materials and components, such as: burner, injection port, wind box, furnace, burnout air burner, etc.

[0025] like Figure 1 The figure shows the coal powder injection trajectory diagram of the combustion area of ​​the anti-coking furnace of the four-corner tangential combustion boiler according to the embodiment of the utility model; Figure 2 and Figure 3 .

[0026] The anti-coking furnace of the four-corner cut-circle combustion boiler of this embodiment includes: a furnace body; the lower inner part of the furnace body is a combustion area, and the upper inner part of the furnace body is a burnout air area; particles that are not fully burned in the combustion area enter the burnout air area for secondary combustion to release energy again.

[0027] Multiple layers of coal powder injection zones are arranged from top to bottom in the combustion area; each layer of the coal powder injection zone includes four coal powder injection ports (respectively, coal powder injection port No. 1 1, coal powder injection port No. 2, coal powder injection port No. 3 and coal powder injection port No. 4) which are centrally symmetrically arranged and located in the same plane; in each layer of the coal powder injection zone, at least two of the coal powder injection ports are inclined.

[0028] Generally, the arrangement of the pulverized coal injection ports in each pulverized coal injection zone is the same. Figure 1 and Figure 2 and Figure 3 Only one layer of the layout is drawn.

[0029] The utility model tilts part of the coal powder injection port so that the coal powder can be burned in order in sequence and in layers; oxygen is concentrated in a planned manner to provide part of the coal powder for combustion, leaving enough space for part of the coal powder that is not fully burned to enter the area to be burned. In this way, the orderly combustion of the coal powder particles in the combustion area is achieved, which not only reduces the generation of NOx, but also avoids various situations in which the thick unburned flame smoke carries molten particles. The utility model changes the single-layer tangential circle combustion in the prior art into a double-layer wide-width tangential circle, so that part of the coal powder can fully contact sufficient oxygen and burn at the same time, and leaves space for the unburned coal powder particles to continue to rise until they are fully mixed with the burnout wind and burned.

[0030] The utility model avoids the disorderly collision and adhesion of molten unburned carbon particles to grow larger, and resolves the phenomenon that the unburned carbon particles, after growing larger, impact and adhere to the water-cooled wall under the action of the tangential circle centrifugal force, resulting in slag and coking in the furnace.

[0031] like Figure 4 and Figure 5 , multiple layers of overburnt air injection zones are arranged from top to bottom in the overburnt air zone; Figure 4 and Figure 5 Four layers of burnout air injection areas are set up in the middle.

[0032] Each layer of the burnout wind injection zone includes four burnout wind injection ports 5 on the same plane; in each layer of the burnout wind injection zone, the injection trajectories of the four burnout wind injection ports are located on the circumference of the same inscribed circle, and the diameter of the inscribed circle is the inscribed circle airflow diameter; the inscribed circle airflow diameters of two adjacent burnout wind injection zones are different.

[0033] Generally, the arrangement of the burnout air injection ports in each burnout air injection zone is the same.

[0034] At the same time, each layer of the burnout air in the burnout air injection zone is divided regularly. When the unburned carbon particles enter, due to the different diameters of the inscribed circular airflows in the two upper and lower adjacent burnout air injection zones, the unburned coal powder particles with different combustion degrees can enter different inscribed circular airflows for combustion. The entire burnout area forms layers of inscribed circular wind-wrapped coal, which is fully mixed and burned, eliminating the impact and bonding of unburned particles and the coking phenomenon, greatly reducing the coking phenomenon caused by disordered combustion.

[0035] like Figure 4 As shown, the diameters of the inscribed circular airflows of the multiple layers of the overburnt air injection zone gradually increase from top to bottom. The diameter of the inscribed circular airflow 10 of the top layer, the diameter of the inscribed circular airflow 20 of the second layer, the diameter of the inscribed circular airflow 30 of the third layer and the diameter of the inscribed circular airflow 40 of the bottom layer increase in sequence.

[0036] like Figure 5 As shown, the diameters of the inscribed circular airflows of the multiple layers of the overburnt air injection zone gradually decrease from top to bottom. The diameter of the inscribed circular airflow 10 of the top layer, the diameter of the inscribed circular airflow 20 of the second layer, the diameter of the inscribed circular airflow 30 of the third layer and the diameter of the inscribed circular airflow 40 of the bottom layer decrease in sequence.

[0037] The gradual increase or decrease in the diameter of the inscribed circular airflow in the multi-layer overburnt air injection zone can allow unburned coal powder particles with different combustion degrees to enter different inscribed circular airflows, so that the overburnt air area can fully utilize the overburnt air for orderly combustion.

[0038] like Figure 1 As shown; in each layer of the coal powder injection area, the inclination angles of the two coal powder injection ports spaced apart from each other are the same, and the other two coal powder injection ports are located in the plane where the coal powder injection area of ​​the layer is located.

[0039] Figure 1 In the figure, the four coal powder injection ports in the coal powder injection area of ​​this layer are located on the same reference plane B, and the No. 1 coal powder injection port 1 and the No. 3 coal powder injection port 3 are tilted upward so that the injection trajectory is located on the upper plane A; the No. 2 coal powder injection port 2 and the No. 4 coal powder injection port 4 remain horizontal and are also located on the same reference plane B.

[0040] Similarly, the No. 1 pulverized coal injection port 1 and the No. 3 pulverized coal injection port 3 can also be tilted downward at the same time so that the injection trajectory is located on the lower plane C.

[0041] Since the No. 1 pulverized coal injection port 1 and the No. 3 pulverized coal injection port 3 are facing upward or downward, they do not burn synchronously with the No. 2 pulverized coal injection port 2 and the No. 4 pulverized coal injection port 4, and no longer compete for oxygen-rich air, so that combustion proceeds in an orderly manner.

[0042] like Figure 2As shown, in another embodiment of the utility model, in each layer of the coal powder injection area, the inclination angles of the two coal powder injection ports spaced apart from each other are the same and are both inclined upward; the inclination angles of the other two coal powder injection ports are the same and are both inclined downward.

[0043] The four coal powder injection ports in this coal powder injection area are located on the same reference plane B. The No. 1 coal powder injection port 1 and the No. 3 coal powder injection port 3 are tilted upward so that the injection trajectory is located on the upper plane A; the No. 2 coal powder injection port 2 and the No. 4 coal powder injection port 4 are tilted downward and are also located on the lower plane C.

[0044] In this embodiment, the coal powder injection ports are swung up or down one by one to form a wide shape of four-cornered double-tangent circles. The angle of the tangent circles remains unchanged, the diameter of the tangent circles remains unchanged, and the upper and lower swung angles widen the tangent circle flame, which is conducive to the No. 2 coal powder injection port 2 and the No. 4 coal powder injection port 4 to burn first after they are ejected. There is abundant oxygen and loose combustion space, and the particles that are easy to coke can burn freely. If they are not molten, there will be no collision and bonding to form coke. After burning out, space is freed up. After the No. 1 coal powder injection port 1 and the No. 3 coal powder injection port 3 are ejected, they are limited by the amount of oxygen and fail to burn or burn out. Fortunately, there is loose space to fly, and they rise steadily to the burnout area, and are fully mixed and burned with the well-divided layers of burnout wind. If they are not crowded, disordered, collided, and bonded, there will be no bonding and coking. This is the orderly combustion of the wide-width tangent circle in layers, which also provides space for unburned carbon particles to avoid collision, bonding, and coking of unburned carbon particles. Reducing the amount of coarse particles that stick to the water-cooled wall will reduce the direct impact of the centrifugal force of the cutting circle on the bonding water-cooled wall, and the particles that are prone to coking will not be able to take root, thus avoiding the occurrence of coking in the furnace.

[0045] like Figure 3 The figure shows another embodiment of the utility model; the four coal powder injection ports in the coal powder injection zone of this layer are located on the same reference plane B, the No. 1 coal powder injection port 1 is tilted upward so that the injection trajectory is located on the upper plane A; the No. 3 coal powder injection port 3 is tilted downward and is located on the lower plane C; the No. 2 coal powder injection port 2 and the No. 4 coal powder injection port 4 remain horizontal and are also located on the same reference plane B.

[0046] At this time, the pulverized coal injected from the No. 3 pulverized coal injection port 3 is preferentially burned in oxygen-rich combustion, the pulverized coal injected from the No. 2 pulverized coal injection port 2 and the No. 4 pulverized coal injection port 4 is burned normally with low nitrogen; the pulverized coal injected from the No. 1 pulverized coal injection port 1 is partially burned with low nitrogen. The three can burn in an orderly manner, and all can reduce the flame temperature, and greatly reduce the adhesion of unburned particles caused by the current crowded collision.

[0047] In the anti-coking furnace of the four-corner tangential combustion boiler of this embodiment, in each layer of the pulverized coal injection area, the inclination angle of each pulverized coal injection port is adjustable. Generally, the inclination angle of the pulverized coal injection port is 8 to 15 degrees.

[0048] The furnace of the utility model has strong adaptability to multiple coal types. In order to determine whether the inclination angle of the coal powder injection port is upward or downward, the fuel ratio is mainly obtained based on the fixed carbon ratio and the volatile matter ratio.

[0049] For example, taking the ratio of 2 as the boundary, when the ratio is less than 2, the combustion speed increases, and the upward swing angle can slow down the impact and adhesion of carbon particles, while taking into account the adjustment of steam temperature; when the ratio is greater than 2, the combustion speed is relatively slow, and the downward swing angle prolongs the combustion time, which is conducive to the burnout of unburned carbon particles; when the ratio is close to 2, the combustion speed matches the furnace height, and the swing angles intersect up and down to maintain stable combustion.

[0050] The utility model embodiment also provides a method for preventing coking of a four-corner tangential combustion boiler, which adopts the four-corner tangential combustion boiler anti-coking furnace of the above embodiment; wherein a secondary air injection area is arranged between two adjacent layers of coal powder injection areas in the combustion area.

[0051] That is to say, secondary air is injected between two adjacent layers of pulverized coal injection zones in the combustion area, so that the pulverized coal is completely wrapped by the secondary air, thereby preventing the pulverized coal from contacting the inner wall of the furnace during combustion.

[0052] like Figures 1 to 5 As shown, the pulverized coal injection ports in two adjacent pulverized coal injection zones in the combustion zone correspond to each other in the vertical direction; the nozzles in the overburnt air zone also correspond to each other in the vertical direction, and are generally located on the same vertical projection plane.

[0053] At least three layers of burnout wind injection zones are arranged in the burnout wind area; the air volume and air pressure output by the nozzles of the burnout wind injection zone in the lowest layer and the burnout wind injection zone in the uppermost layer are greater than the air volume and air pressure output by the nozzles of the burnout wind injection zone in the middle layer.

[0054] like Figure 4 and Figure 5 As shown, the air volume and air pressure output by the nozzles in the bottom and top burnout air injection zones are greater than the air volume and air pressure output by the nozzles in other layers.

[0055] The top and bottom overburnt air injection areas are the focus of air volume, which improves the function of overburnt air from a structural perspective, and surrounds the overburnt air layer by layer to avoid repeated coverage and omission of overburnt air areas. If the overburnt air cannot be fully mixed with the fuel-rich flame flue gas in the overburnt area, it will not be able to eliminate molten particles and CO in seconds, and it will not be able to eliminate the slagging and coking phenomenon in the furnace.

[0056] In addition, the anti-coking furnace of the four-corner tangential combustion boiler of the utility model has low implementation cost, exquisite layout, compact structural design, is not easy to coke, does not require additional kaolin doping, is easy to maintain, is suitable for various four-corner tangential combustion boilers, and is particularly suitable for the combustion of Zhundong coal.

[0057] The serial numbers of the above-mentioned embodiments of the utility model are only for description and do not represent the advantages and disadvantages of the embodiments. Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of some deformations plus the necessary general technology superposition; of course, it can also be implemented by simplifying some important technical features. Based on this understanding, the technical solution of the utility model is essentially or the part that contributes to the prior art is: the overall structure and connection method, and the structure described in each embodiment of the utility model.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the utility model.

Claims

1. A coking-proof furnace of a four-corner tangential combustion boiler, characterized in that: include: The lower part of the chamber body is a combustion area, and the upper part of the chamber body is a burnout air area; Multiple layers of pulverized coal injection zones are arranged from top to bottom in the combustion zone; each layer of the pulverized coal injection zone includes four pulverized coal injection ports that are centrally symmetrically arranged and located in the same plane; in each layer of the pulverized coal injection zone, at least two of the pulverized coal injection ports are inclinedly arranged.

2. The anti-coking furnace of the tangentially fired boiler according to claim 1 is characterized in that: Multiple layers of burnt-out air injection zones are arranged from top to bottom in the burnt-out air zone; Each layer of the burnout wind injection zone includes four burnout wind injection ports on the same plane; in each layer of the burnout wind injection zone, the injection trajectories of the four burnout wind injection ports are located on the circumference of the same inscribed circle, and the diameter of the inscribed circle is the inscribed circle airflow diameter; the inscribed circle airflow diameters of two adjacent burnout wind injection zones are different.

3. The anti-coking furnace of the tangentially fired boiler according to claim 2 is characterized in that: The diameter of the inscribed circle airflow in the multi-layer overburnt air injection zone increases gradually from top to bottom.

4. The anti-coking furnace of the tangentially fired boiler according to claim 2 is characterized in that: The diameter of the inscribed circle airflow in the multi-layer overburnt air injection zone gradually decreases from top to bottom.

5. The anti-coking furnace of the tangentially fired boiler according to any one of claims 2 to 4, characterized in that: In each layer of the pulverized coal injection area, the inclination angles of two pulverized coal injection ports spaced apart from each other are the same, and the other two pulverized coal injection ports are located in the plane where the pulverized coal injection area of ​​the layer is located.

6. The anti-coking furnace of the tangentially fired boiler according to any one of claims 2 to 4, characterized in that: In each layer of the pulverized coal injection area, the two pulverized coal injection ports spaced apart from each other have the same inclination angle and are both inclined upward; the other two pulverized coal injection ports have the same inclination angle and are both inclined downward.

7. The anti-coking furnace of the tangentially fired boiler according to any one of claims 2-3, characterized in that: In each layer of the pulverized coal injection area, the inclination angle of each pulverized coal injection port is adjustable.

8. The anti-coking furnace of the tangentially fired boiler according to any one of claims 2-3, characterized in that: The inclination angle of the coal powder injection port is 8 to 15 degrees.

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