Method and device for warehouse-divided and layered blending combustion of meagre coal boiler
By using a compartmentalized and layered co-firing method and an air path isolation device, the problem of unstable combustion of lean coal boilers under low load was solved, and the adaptation of multiple coal types and air path isolation were achieved, thereby improving combustion efficiency and safety.
Patent Information
- Application Number
- CN202511325538.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-17
- Publication Date
- 2025-12-16
AI Technical Summary
Lean coal boilers have unstable combustion under low load, making it difficult to adapt to the needs of various coal types. In addition, poor air isolation leads to low combustion efficiency and poses safety hazards.
The method of compartmentalized and layered co-firing is adopted, with bituminous coal and lean coal stored and ground separately. They are burned through independent primary air supply and layered burners, combined with air path isolation devices to achieve reliable air path isolation and temperature adaptation, and plasma burners are used for stable combustion under low load.
It improves combustion efficiency, reduces operation and maintenance costs, enhances combustion stability and safety, and achieves stable operation under low load.
Smart Images
Figure CN121139952A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of boiler combustion, in particular to a lean coal boiler sub-bin sub-layer blending combustion method and device. BACKGROUND
[0002] Current thermal power generating units are facing the demand of deep peak regulation. As the main type of unit, lean coal boilers have two core pain points due to the characteristics of lean coal "high heat release, low volatile matter, and difficult low load combustion". One is that the minimum stable load is usually only 40%, which cannot meet the demand of 25% low load operation required by the policy. The other is that the cost of single burning of lean coal is high, and it is urgent to blend low-price bituminous coal to reduce the cost, but the characteristics of bituminous coal "high volatile matter, afraid of high temperature" are contradictory to the adaptation demand of lean coal, and the existing blending scheme is difficult to be compatible.
[0003] The technical defects of existing lean coal boiler blending bituminous coal are concentrated in three aspects: first, there is no sub-bin sub-layer design, and bituminous coal and lean coal are mixed in the bin and mixed and ground, which leads to the fact that the primary air cannot simultaneously adapt to the combustion demand of the two kinds of coal. If the single-temperature primary air is set to high temperature (280-320℃) according to the demand of lean coal, it is easy to cause the volatile matter of bituminous coal to be precipitated in advance, causing the powder conveying pipe to be blocked or even exploded. If the temperature is reduced according to the demand of bituminous coal, the ignition temperature of lean coal is insufficient, and the combustion efficiency is sharply reduced. Second, the wind path isolation of the primary air connection pipe is usually single baffle structure, and the baffle on both sides bears a high and low temperature difference (more than 100℃) of the primary air for a long time, which is easy to cause thermal stress warping and cracking, leading to sealing failure, high-temperature air flow and coal powder leakage, which not only destroys the stability of combustion, but also increases the risk of self-ignition of accumulated powder. Third, under low load conditions, the amount of bituminous coal powder is small, and the conventional burner is difficult to burn stably, which needs to rely on oil injection for combustion, which increases the operation and maintenance cost, and the replacement cycle of the parts is short (1.5-2 years) due to coal powder erosion and temperature difference fatigue, and the operation and maintenance workload is large. SUMMARY
[0004] Therefore, the technical problem to be solved by the present application is that the boiler cannot meet the three demands of "low load stable combustion, coal adaptation, and reliable isolation of temperature difference" in the process of combustion, cannot realize the blending scheme of sub-bin coal supply, sub-temperature primary air supply, and temperature difference self-adaptive isolation, and the combustion efficiency of the boiler is low.
[0005] The above technical problems are solved by the following technical scheme: the present application provides a lean coal boiler sub-bin sub-layer blending combustion method, which comprises: independently storing bituminous coal and lean coal in the independent raw coal bin and conveying them to the corresponding coal mill group for grinding; respectively conveying bituminous coal and lean coal to the corresponding coal mill group for grinding; and the temperature of the bituminous coal-adapted primary air is lower than that of the lean coal-adapted primary air; the primary air carries the corresponding coal powder to the lower and upper layer burners for combustion; and the wind path isolation device on the connection pipe selectively blocks or connects the air flow of the two wind paths.
[0006] In a preferred embodiment of the lean coal boiler warehouse layering blending method and device, at least two independent raw coal warehouses are provided for storing and transporting bituminous coal and lean coal to the first and second coal mill groups, respectively.
[0007] In a preferred embodiment of the lean coal boiler warehouse layering blending method and device, the bituminous coal adaptive primary air and the lean coal adaptive primary air are matched with the combustion characteristics of the bituminous coal and the lean coal, respectively, and the lean coal adaptive primary air is formed by heating cold air through an air preheater, and the bituminous coal adaptive primary air is formed by mixing the lean coal adaptive primary air and cold air.
[0008] In a preferred embodiment of the lean coal boiler warehouse layering blending method and device, the temperature of the bituminous coal adaptive primary air is in a temperature range matching the combustion of the bituminous coal, the temperature of the lean coal adaptive primary air is in a temperature range matching the combustion of the lean coal, and the upper limit of the temperature range of the bituminous coal adaptive primary air is lower than the lower limit of the temperature range of the lean coal adaptive primary air.
[0009] In a preferred embodiment of the lean coal boiler warehouse layering blending method and device, the bituminous coal adaptive primary air carries the bituminous coal powder to the lower burner, the lean coal adaptive primary air carries the lean coal powder to the upper burner, and the bituminous coal powder and the lean coal powder are transported through independent powder conveying pipes, respectively.
[0010] In a preferred embodiment of the lean coal boiler warehouse layering blending method and device, when the boiler is in a low load condition, the lean coal side coal mill group and the upper burner are stopped, only the lower burner is combusted, and the plasma burner in the lower burner is started to achieve stable combustion.
[0011] In a preferred embodiment of the lean coal boiler warehouse layering blending method and device, when the air path isolation device is closed, zero leakage isolation of the two air paths is achieved, when the air path isolation device is opened, the air flow of the two air paths can be communicated, the air path isolation device is adapted to the scouring environment of the primary air containing coal powder, and can stably work in the temperature range of the bituminous coal adaptive primary air and the lean coal adaptive primary air.
[0012] To solve the above technical problems, the present application also provides the following technical scheme: a lean coal boiler warehouse layering blending method device, which comprises a coal conveying pipe group, a separation valve, a sealing assembly, and a transmission cavity.
[0013] In a preferred embodiment of the method and device for mixed combustion of lean coal in a lean coal boiler, the sealing member is provided with two groups, the sealing member is composed of two groups of insertion plates, and the push rod is also provided with two groups of insertion plates matched with the sealing member.
[0014] In a preferred embodiment of the method and device for mixed combustion of lean coal in a lean coal boiler, the insertion plate comprises a protruding block, an insertion slot, an abutting table and an extension block, the protruding block is inserted into the insertion slot, the extension block is matched with the abutting table, the inclination of the side wall of the insertion slot is the same as that of the side wall of the protruding block, the depth of the insertion slot is greater than the length of the protruding block, and the end of the extension block comprises a flat end and an arc-shaped end.
[0015] The method and device for mixed combustion of lean coal in a lean coal boiler have the following advantages: the features of coal supply in different compartments, adaptation of primary air supply, layer combustion, air path isolation device, low-load plasma combustion stabilization and independent powder supply pipeline can avoid the conflict between bituminous coal and lean coal, can take into account the combustion efficiency and prevent volatile explosion by adapting primary air (bituminous coal or lean coal), can realize low-load deep adjustment by layer combustion and plasma combustion stabilization, can prevent air leakage and powder leakage by air path isolation device, can seal the communication pipe by closer matching of the communication pipe through the insertion and matching of the insertion plates, and the like. BRIEF DESCRIPTION OF DRAWINGS
[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below only relate to some embodiments of the present application, but not limit the present application. Among them:
[0017] Figure 1 A structure schematic diagram of the device for mixed combustion of lean coal in a lean coal boiler is shown;
[0018] Figure 2 A split schematic diagram of the device for mixed combustion of lean coal in a lean coal boiler is shown;
[0019] Figure 3 A split schematic diagram of the device for mixed combustion of lean coal in a lean coal boiler is shown;
[0020] Figure 4 A structure schematic diagram of the insertion plate in the device for mixed combustion of lean coal in a lean coal boiler is shown;
[0021] Figure 5 A sectional view of the device for mixed combustion of lean coal in a lean coal boiler is shown;
[0022] Figure 6 A primary air flow direction schematic diagram of the device for mixed combustion of lean coal in a lean coal boiler is shown; DETAILED DESCRIPTION
[0023] For those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with specific embodiments and accompanying drawings.
[0024] The terms used in the present application are those general terms currently widely used in the art in consideration of the functions of the present application, but the terms can be changed according to the intention of those of ordinary skill in the art, precedents, or new technology in the art. In addition, specific terms can be selected by the applicant, and in this case, the detailed meaning thereof will be described in the detailed description of the present application. Therefore, the terms used in the specification should not be understood as mere names, but based on the meaning of the terms and the overall description of the present application.
[0025] Reference Figures 1-6 In the drawings, only the connection part of the pipeline is shown, and the total length of the pipeline is not represented, the embodiment provides a lean coal boiler warehouse and layering blending combustion method and device, including warehouse coal supply, at least two independent raw coal warehouses are provided, one is used for storing bituminous coal, and the other is used for storing lean coal, and there is no communication structure between the two warehouses to avoid mixing of coal types. The bituminous coal is sent to the first coal mill unit through the bottom conveying device, and the lean coal is sent to the second coal mill unit through another independent conveying device. During the conveying process, the material level of the two warehouses is controlled in real time through the material level monitoring device to ensure continuous and stable coal supply. The first and second coal mill units grind the bituminous coal and lean coal respectively, and the fineness of the ground coal is adjusted according to the characteristics of the coal (the bituminous coal powder is slightly coarse to adapt to its high volatile matter, and the lean coal powder is slightly fine to promote combustion).
[0026] Further, the primary air supply is distributed: the bituminous coal is supplied with bituminous coal adaptive primary air, and the lean coal is supplied with lean coal adaptive primary air, and the temperature of the bituminous coal adaptive primary air is lower than that of the lean coal adaptive primary air. Among them, the lean coal adaptive primary air is obtained by heating cold air through an air preheater, and the bituminous coal adaptive primary air is obtained by mixing part of the lean coal adaptive primary air with unheated cold air in a mixing device. The temperature difference is controlled by adjusting the mixing ratio of cold air to ensure that the combustion characteristics of bituminous coal and lean coal are matched respectively (bituminous coal needs lower temperature to avoid early release of volatile matter, and lean coal needs higher temperature to meet the ignition requirement).
[0027] Further, the combustion is layered: the bituminous coal adaptive primary air carries the bituminous coal powder ground by the first coal mill unit, and is conveyed to the lower burner of the boiler furnace through a special pipeline; the lean coal adaptive primary air carries the lean coal powder ground by the second coal mill unit, and is conveyed to the upper burner of the furnace through another special pipeline. The bituminous coal flame sprayed by the lower burner provides a preheating heat source for the upper lean coal flame, and the heat released by the upper lean coal combustion raises the overall temperature of the furnace, forming a layered and collaborative combustion effect.
[0028] Further, wind path isolation: a wind path isolation device is arranged on the connecting pipe between the bituminous coal adaptive primary air path and the lean coal adaptive primary air path. In normal blending combustion, the control device is closed to block the air flow of the two wind paths, avoiding the interference of the temperature difference of the primary air in series flow on combustion; when a certain coal mill unit fails, the control device is opened to connect the two wind paths, realizing the complementary supply of primary air, and ensuring the stable operation of the boiler.
[0029] Specifically, two independent raw coal bunkers (may be increased to three or more according to requirements) are arranged, one is designed for bituminous coal, and the other is designed for lean coal. The inlet and outlet of the two bunkers are respectively connected to independent coal conveying systems. The bituminous coal in the No. 1 bunker is quantitatively conveyed to the first coal mill unit by a frequency conversion coal feeder, and the lean coal in the No. 2 bunker is quantitatively conveyed to the second coal mill unit by another frequency conversion coal feeder. The coal supply amount is adjusted in real time according to the boiler load to ensure that the pulverized coal supply amount matches the load demand.
[0030] Specifically, the temperature range of the bituminous coal adaptive primary air matches the combustion characteristics of bituminous coal (high temperature should be avoided to prevent rapid release of volatile matter), and the temperature range of the lean coal adaptive primary air matches the combustion characteristics of lean coal (high enough temperature is needed to ensure ignition). The preparation process of the lean coal adaptive primary air is: cold air is sent into the air preheater by the air blower, and after heat exchange with the boiler exhaust gas, the temperature is raised to the temperature range of the lean coal adaptive primary air. The preparation process of the bituminous coal adaptive primary air is: part of the gas flow is introduced from the lean coal adaptive primary air pipe, mixed with the unheated cold air at the outlet of the air blower in the mixing device, and the temperature is controlled in the bituminous coal adaptive range by adjusting the opening degree of the cold air valve. The mixed gas flow is sent to the first coal mill unit through a special pipe.
[0031] Further, the upper limit value of the temperature range of the bituminous coal adaptive primary air is lower than the lower limit value of the temperature range of the lean coal adaptive primary air, ensuring that there is a clear temperature difference between the two to adapt to the characteristics of the coal respectively. For example: the temperature range of the bituminous coal adaptive primary air is overall lower than that of the lean coal adaptive primary air, and the two ranges do not overlap. Real-time monitoring and feedback adjustment are realized through temperature sensors to ensure that the bituminous coal side is always in a safe combustion temperature range and the lean coal side is always in an easy-to-ignite temperature range. The bituminous coal powder is conveyed to the lower burner through the first independent powder conveying pipe, and the lean coal powder is conveyed to the upper burner through the second independent powder conveying pipe. The two pipes are arranged in parallel and do not cross and communicate. The first powder conveying pipe is connected to the bituminous coal adaptive primary air path, and the second powder conveying pipe is connected to the lean coal adaptive primary air path. The inner wall of the pipe is made of wear-resistant material (such as steel plate with sprayed wear-resistant coating, example material 1: Q345R steel base material + WC-Co hard alloy coating, which can resist long-term scouring of coal powder, which meets the requirements here and is not limited in specific).
[0032] Further, stop #2 raw coal bunker to the second coal mill group coal, close the upper layer of the burner into the powder valve, only remain the lower layer of the burner operation; Start the plasma burner in the lower layer of the burner at the same time, use the high temperature of the plasma arc to ignite the bituminous coal powder directly, realize the stable combustion under the low load. The electrode of the plasma burner uses the high temperature resistant conductive material (example material 2: tungsten copper alloy, can withstand the high temperature above 600 DEG C and the stable conductive performance), ensure that the ignition energy can be maintained under the low coal powder amount.
[0033] Further, when the air path isolation device is closed, the sealing structure closely fits the inner wall of the communication pipe, realizing the zero leakage isolation of the two air paths; When it is opened, the device structure is completely opened, allowing the air flow of the two air paths to pass through the communication pipe. The device needs to adapt to the scouring environment of the primary air containing coal powder (coal powder particles will continuously hit the surface), and can work stably in the temperature range of the primary air suitable for bituminous coal and the primary air suitable for lean coal (need to resist the thermal stress generated by temperature change). The sealing element of the device can use temperature resistant and wear resistant elastic material, which is not limited here (example material 3: perfluoro ether rubber, can maintain elasticity in the range of-20 DEG C to 320 DEG C, and has excellent coal powder wear resistance), the plug main body uses high strength alloy material (such as 12Cr1MoV alloy steel, has high temperature strength and anti creep performance), which can ensure that the sealing precision can be maintained after long term operation, which is not limited here.
[0034] Specifically, when the boiler needs to switch from low load (only bituminous coal combustion) to high load (bituminous coal + lean coal blending combustion), first start the second coal mill unit to preheat (idle for 10-15 minutes, not limited specifically, just to avoid cold start causing coal powder caking), at the same time, adjust the bituminous coal through the cold air mixing device to ensure that it is stable in the bituminous coal combustion adaptation range; then open the #2 raw coal bunker feeder, increase the lean coal coal supply at a rate of "5% / minute", and start the upper burner at the same time; after the lean coal powder is stably transported to the upper burner through the independent pulverized coal conveying pipe, gradually increase the lean coal adaptive primary air volume until the boiler load reaches the target value (such as 100% rated load), and the entire transition process has no load fluctuation (deviation ≤±2%); further, when the load needs to be reduced from high load to low load, first reduce the lean coal coal supply at a rate of "3% / minute", and simultaneously reduce the lean coal adaptive primary air volume; after the lean coal coal supply is reduced to 0, the second coal mill unit and the upper burner are closed, and the lean coal adaptive primary air valve is closed; at this time, only the lower burner is kept running, if the load is less than 40%, the plasma burner is automatically started (without manual intervention), the ignition energy is adjusted through arc pressure feedback, to ensure stable combustion of bituminous coal powder and avoid extinguishing, if the first coal mill unit fails, immediately control the air path isolation device to open (response time ≤5 seconds), so that the lean coal adaptive primary air is supplemented to the bituminous coal adaptive primary air path through the connecting pipe; at the same time, the #1 raw coal bunker feeder is closed, the #2 raw coal bunker feeder is started and the lean coal coal supply is increased, the lean coal powder is transported to the lower burner through the original bituminous coal pulverized coal conveying pipe, to realize the "full lean coal combustion" emergency mode, to ensure that the boiler load is stable at more than 80%, until the first coal mill unit is repaired.
[0035] Further, as Figure 6As shown, the coal pipe group 1, including the bituminous coal pipe 11 and the lean coal pipe 12, the bituminous coal pipe 11 is used to connect the bituminous coal bin to transport the bituminous coal, the lean coal pipe 12 is used to connect the lean coal bin to transport the lean coal, the communication pipe 13 is arranged between the bituminous coal pipe 11 and the lean coal pipe 12, the communication pipe 13 is used to connect the bituminous coal pipe 11 and the lean coal pipe 12, so that the temperature of the bituminous coal and the lean coal is mutually supplemented by the interconnection of the two pipes, the isolation valve 2 is inserted and matched with the communication pipe 13, the isolation valve 2 is used to cut off the connection between the bituminous coal pipe 11 and the lean coal pipe 12 when the communication pipe 13 is not used, a conduction cavity 21 is formed in the isolation valve 2, and there is a certain gap between the two sealing elements 32 in the conduction cavity 21. The space can be used for temperature conduction. Because there is a certain temperature difference between the two ends of the communication pipe 13, the temperature difference between the bituminous coal pipe 11 and the lean coal pipe 12 usually reaches 150℃, so the conventional sealing element 32 will appear uneven heating of the two end sidewalls, resulting in bending and deformation of the whole. Therefore, two groups of sealing elements 32 can be arranged to seal the two openings of the communication pipe 13 and the isolation valve 2, which can achieve the effect of closing the communication pipe 13. Then, the temperature conducted by the bituminous coal pipe 11 and the temperature conducted by the lean coal pipe 12 will be conducted through the two groups of sealing elements 32, respectively. The final heat will be introduced into the conduction cavity 21, and the temperature in the conduction cavity 21 will be half of the sum of the temperature conducted by the bituminous coal pipe 11 and the temperature conducted by the lean coal pipe 12. In this way, the temperature difference between the two ends of the sealing element 32 can be greatly reduced, thereby prolonging the service life of the sealing element 32 and forming a protective effect on the sealing element 32. The through hole 22 is formed on the two sides of the isolation valve 2 and communicates with the conduction cavity 21. The sealing assembly 3 includes the push rod 31 which is in sliding fit with the through hole 22. The push rod 31 can be driven by gas or liquid pressure or other driving methods. In this embodiment, the push rod 31 is driven by gas. The output end of the push rod 31 can be driven by an electrical signal to facilitate simple operation. The sealing element 32 is fixedly connected with the push rod 31 and slides in the conduction cavity 21.
[0036] Furthermore, the sealing element 32 is provided in two sets, each consisting of two sets of insert plates 321. The two sets of insert plates 321 achieve a better sealing effect through abutment, and significantly reduce space requirements. If a single insert plate 321 were used, its length would need to be increased, and the sliding cavity for that single plate would need to be enlarged on one side. To prevent misalignment at the center, symmetry is required, which would increase space. Most importantly, the push rod 31 may deviate during pushing. If a single insert plate 321 were used, a slide rail would be necessary, which could lead to blockage. Therefore, this embodiment uses a two-set insert plate 321 scheme. The two sets of insert plates 321 mutually restrain each other during insertion, thus achieving a better seal. The push rod 31 is also provided in two sets to cooperate with the sealing element 32. The two sets of sealing elements 32 respectively fit into the connection points of the connecting pipe 13 and the isolation valve 2 to achieve a seal.
[0037] Furthermore, the insert plate 321 includes a protrusion a, a slot b, an abutment c, and an extension block d. The protrusion a is inserted into the slot b, and the extension block d fits against the abutment c. The sidewall of the slot b has the same inclination as the sidewall of the protrusion a. Since the sidewalls of both the protrusion a and the slot b are set to be inclined, this allows for better adaptation to the mutual compression that causes the outer sidewall of the protrusion a to fit against the opening of the connecting pipe 13. The depth of the slot b is greater than the length of the protrusion a, allowing the protrusion a to have space to slide into the slot b, thus providing a certain amount of reserved space for the protrusion a to compress the sidewall of the slot b outward. The end of the extension block d includes a flat end d1 and an arc-shaped end d2. Most importantly, when the two sets of insert plates 321 are inserted and mated, the insert plates 321 need to remain in contact with the side near the opening of the connecting pipe 13. At this time, when the protrusion a is inserted... When the extension block d is inserted into slot b, the flat end d1 of the extension block d is not in contact with the abutment platform c. If the insert plate 321 fails to fit against the opening of the connecting pipe 13 for various reasons, such as wear caused by the scouring and friction of coal powder on both sides of the connecting pipe 13, or deformation caused by temperature difference on both sides, the push rod 31 will continuously apply force to the insert plate 321, causing the two sets of insert plates 321 to press against each other until the extension block d moves towards the side closer to the opening of the connecting pipe 13, causing the entire extension block d to tilt and abut against the opening of the connecting pipe 13. During the process of the extension block d tilting towards the opening of the connecting pipe 13, the arc-shaped end d2 of the extension block d will contact the abutment platform c. At this time, as the protrusion a continues to push into slot b, the arc-shaped end d2 will always be in contact with the abutment platform c, forming a seal at the opening of the connecting pipe 13.
[0038] In summary, at least two independent raw coal silos are set up to store bituminous coal and lean coal respectively; corresponding coal mills are used for separate grinding (bituminous coal is suitable for medium-speed mills, and lean coal is suitable for wear-resistant coal mills); bituminous coal powder is transported to the lower burner of the furnace and lean coal powder is transported to the upper burner through two independent pulverization pipelines, forming a "dedicated coal, dedicated pipeline" physical isolation; the high-temperature flame generated by the combustion of bituminous coal in the lower layer preheats the upper layer of lean coal, resolving the conflict of coal mixing, and improving the combustion efficiency compared to traditional co-firing; the primary air suitable for lean coal is prepared by heating cold air through an air preheater (using the waste heat of boiler exhaust) to meet the high-temperature requirements of lean coal, which is difficult to ignite; the primary air suitable for bituminous coal is regulated by mixing "primary air suitable for lean coal + unheated cold air" to avoid premature precipitation of bituminous coal volatiles; the temperature of the two is clearly defined. The temperature range is "upper limit of bituminous coal adaptability range < lower limit of lean coal adaptability range", which can flexibly adapt to different coal qualities without the need for fixed temperature values. An air path isolation device is installed on the primary air connection pipe for bituminous coal and lean coal adaptability. When closed, it achieves zero leakage isolation (preventing cross-flow of air from damaging combustion). When open, it can connect the air path in an emergency (make-up air to maintain load). The device's sealing parts are made of materials with a temperature resistance of ≥300℃ and resistance to coal dust abrasion. The main body of the baffle plate is made of high-strength alloy with thermal stress resistance, which extends the service life and reduces the air leakage rate compared to traditional single baffles. Under low load conditions, the lean coal side coal mill and upper burner are automatically stopped, and only the lower burner burns bituminous coal. The lower plasma burner is started simultaneously (without oil injection for combustion assistance), and the high-temperature plasma arc is used to directly ignite the bituminous coal powder, thereby reducing the minimum stable load of the boiler.
[0039] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.
Claims
1. A method for layered and compartmented co-firing of lean coal in a boiler, characterized in that: include, Independent raw coal silos store bituminous coal and lean coal separately and transport them to the corresponding coal mill units for grinding. Primary air for bituminous coal and primary air for lean coal are supplied to the corresponding coal mills respectively, and the temperature of the primary air for bituminous coal is lower than that of the primary air for lean coal. The primary air carries the corresponding pulverized coal to the lower and upper burners of the furnace for combustion. The airflow isolation device on the connecting pipe selectively blocks or connects the airflow between the two airflow paths.
2. The method for layered and compartmented co-firing of lean coal in a boiler according to claim 1, characterized in that: There are at least two independent raw coal bunkers, corresponding to the storage of bituminous coal and lean coal, and the transportation to the first and second coal mill units, respectively.
3. The method for layered and compartmented co-firing of lean coal in a boiler according to claim 1, characterized in that: The primary air for bituminous coal and the primary air for lean coal are matched to the combustion characteristics of bituminous coal and lean coal respectively. The primary air for lean coal is formed by heating cold air through an air preheater, while the primary air for bituminous coal is formed by mixing the primary air for lean coal with cold air.
4. The method for layered and compartmented co-firing of lean coal in a boiler according to claim 1, characterized in that: The temperature of the primary air used to match the bituminous coal is within the temperature range that matches the combustion of bituminous coal, and the temperature of the primary air used to match the lean coal is within the temperature range that matches the combustion of lean coal. Furthermore, the upper limit of the temperature range for the primary air used to match the bituminous coal is lower than the lower limit of the temperature range for the primary air used to match the lean coal.
5. The method for layered and compartmented co-firing of lean coal in a boiler according to claim 1 or 4, characterized in that: Bituminous coal is supplied with primary air that carries pulverized bituminous coal to the lower burner, while lean coal is supplied with primary air that carries pulverized lean coal to the upper burner. Bituminous coal pulverized coal and lean coal pulverized coal are transported through separate pulverization pipelines.
6. The method for layered and compartmented co-firing of lean coal in a boiler according to claim 5, characterized in that: When the boiler is under low load, the coal mill on the lean coal side and the upper burner are stopped, and only the lower burner is burned. The plasma burner in the lower burner is started to achieve stable combustion.
7. The method for layered and compartmented co-firing of lean coal in a boiler according to claim 6, characterized in that: When the air path isolation device is closed, it achieves zero-leakage isolation between the two air paths; when it is open, the airflow between the two air paths can be interconnected. Furthermore, the air duct isolation device is adapted to the scouring environment of primary air containing pulverized coal and can work stably within the temperature range suitable for primary air in bituminous coal and primary air in lean coal.
8. An apparatus for a method of layered and compartmented co-firing of lean coal in a boiler, characterized in that: The method for layered co-firing of lean coal in a boiler as described in any one of claims 1 to 7, and; A coal conveying pipe group (1) includes a bituminous coal pipe (11) and a lean coal pipe (12), and a connecting pipe (13) is provided between the bituminous coal pipe (11) and the lean coal pipe (12); An isolation valve (2) is inserted into a connecting pipe (13) and has a conduction cavity (21) inside. Through holes (22) are opened on both sides of the isolation valve (2) and the through holes (22) are connected to the conduction cavity (21). The sealing assembly (3) includes a push rod (31) that slides with the through hole (22) and a seal (32) that is fixedly connected to the push rod (31) and slides within the conduction cavity (21).
9. The apparatus for the method of layered co-firing of lean coal in a boiler according to claim 8, characterized in that: The sealing element (32) is provided in two sets, and the sealing element (32) is composed of two sets of insert plates (321). The push rod (31) is also provided in two sets to cooperate with the sealing element (32). The two sets of seals (32) are respectively attached to the connection points at both ends of the connecting pipe (13) and the isolation valve (2).
10. The apparatus for the method of layered co-firing of lean coal in a boiler according to claim 9, characterized in that: The insert plate (321) includes a protrusion (a), a slot (b), an abutment (c), and an extension block (d). The protrusion (a) is inserted into the slot (b), and the extension block (d) is in contact with the abutment (c). The sidewall of the slot (b) has the same inclination as the sidewall of the protrusion (a), and the depth of the slot (b) is greater than the length of the protrusion (a). The extension block (d) has a planar end (d1) and an arc-shaped end (d2) at its end.