A dual fuel large scale swirl burner

Abstract

The application discloses a dual-fuel large-proportion mixed combustion type swirl burner, which comprises a main fuel primary air inlet, a first fuel primary air inlet, straight flow inner secondary air, swirl outer secondary air, a secondary air swirl straight flow proportion adjusting baffle and a precombustion chamber. The main fuel primary air pipe is a straight pipe, the first fuel primary air inlet is divided into an annular uniform air distribution device and second fuel primary air inlets which are uniformly arranged around the main fuel primary air pipe, are communicated with the outer edge of the main fuel primary air pipe and form a four-corner tangential flow type in the straight pipe section of the main fuel primary air pipe, thereby ensuring that the two different fuels of the main fuel and the secondary fuel are mixed in a large proportion and uniformly in time, and the proportion of the straight flow and the swirl of the secondary air is adjusted according to different mixed proportions through the baffle, so that the optimized combustion organization of the two fuels under different mixed proportions is realized.

Description

A dual-fuel, high-proportion co-firing type swirl burner Technical Field

[0001] This invention belongs to the field of environmental protection technology for power plants, and specifically relates to a dual-fuel, high-proportion co-firing swirl burner. Background Technology

[0002] With the continuous development and utilization of fossil energy, the supply situation of coal is not optimistic. In order to ensure the fuel supply of thermal power plants, the power plants currently in operation often face the need to blend different types of coal, and even non-traditional fossil fuels such as biomass. How to achieve the mixing of different types of coal before entering the furnace for combustion and the optimization of the flow field organization at the burner outlet after the blending ratio changes have put forward higher requirements for the design of existing burners.

[0003] Existing blending methods generally have certain shortcomings, such as the uniformity of blending different fuels, whether the fuel blending ratio can be adjusted, and whether the air distribution method and flow field of the burner can be optimized and adjusted according to different blended fuel types and blending ratios after the burner design is completed. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a dual-fuel, high-proportion co-firing swirl burner. This burner can achieve timely and uniform mixing of the two fuels before they enter the furnace, and adjust the ratio of swirl secondary air to direct-flow secondary air as needed after changes in the mixing ratio of the two fuels. This achieves optimized flow field organization for different fuel mixture characteristics.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A dual-fuel, high-proportion co-firing swirl burner includes a primary fuel duct, a primary fuel inlet and a first fuel primary air inlet connected sequentially to the primary fuel duct, a secondary duct fitted onto the primary fuel duct, and a pre-combustion chamber connected to both the primary fuel duct and the secondary duct; the secondary duct is equipped with a secondary swirl DC proportional adjustment baffle, an inner DC secondary duct, and an outer swirl secondary duct, with swirl vanes installed inside the outer swirl secondary duct.

[0007] A further improvement of the present invention is that the first fuel primary air inlet is divided into an annular uniform air distribution device and a second fuel primary air inlet uniformly arranged around the main fuel primary air duct, wherein the second fuel primary air inlet is connected to the outer edge of the main fuel primary air duct and forms a tangential flow pattern at the four corners in the straight section of the main fuel primary air duct.

[0008] A further improvement of the present invention is that the cross-section of the four second fuel primary air inlets is perpendicular to the flow direction of the main fuel primary air duct.

[0009] A further improvement of the present invention is that the secondary air duct is divided into a direct current internal secondary air duct and a vortex external secondary air duct.

[0010] A further improvement of the present invention is that the DC inner secondary air duct is arranged close to the main fuel primary air duct, and the swirl outer secondary air duct is arranged close to the DC inner secondary air duct.

[0011] A further improvement of the present invention is that both the DC internal secondary air duct and the vortex external secondary air duct are led out from the secondary air duct.

[0012] A further improvement of the present invention is that a secondary air vortex DC ratio adjustment baffle is provided inside the secondary air duct. By adjusting the left and right opening of the secondary air vortex DC ratio adjustment baffle, the ratio of DC to vortex of the secondary air is adjusted according to different mixing ratios, thereby achieving optimized combustion organization of the two fuels under different mixing ratios.

[0013] A further improvement of the present invention is that the secondary air duct is connected to the pre-combustion chamber via a DC secondary air vent.

[0014] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0015] The present invention discloses a dual-fuel, high-proportion blending swirl burner. In specific operation, four secondary fuel primary air inlets are arranged on a cross-section perpendicular to the primary fuel primary air flow direction. The extension lines of these four secondary fuel primary air inlets form a tangent circle of radius R within the primary fuel primary air duct. Mimicking the flow field organization of tangent-circle combustion, the primary air of the secondary fuel, flowing in a tangent-circle pattern within the primary air duct, enhances the mixing with the primary fuel primary air, resulting in a uniform blend of the primary and secondary fuels before entering the furnace. The radius R needs to be optimized based on the actual density difference between the primary and secondary fuels. By rationally setting the rotational momentum of the secondary fuel primary air, uniform mixing of the two fuels is achieved with minimal flow resistance. Furthermore, after determining the fuel types and blending ratios of the primary and secondary fuels, the ratio of direct current and swirl secondary air entering the furnace can be adjusted using a secondary air swirl direct current ratio adjusting baffle installed within the secondary air duct. The ratio of direct current and swirl secondary air is optimized based on the characteristics of the predetermined fuel types and blending ratios of the primary and secondary fuels. For example, for difficult-to-ignite blended primary and secondary fuels, it is necessary to increase the flow rate of the swirl secondary air to enhance the entrainment of high-temperature flue gas in the furnace within the pre-combustion chamber, thereby increasing the average temperature within the pre-combustion chamber and ensuring that the blended primary and secondary fuels ignite promptly upon entering the pre-combustion chamber. Conversely, for easily flammable blended primary and secondary fuels, it is necessary to appropriately reduce the flow rate of the swirl secondary air and increase the flow rate of the direct-flow secondary air to moderately weaken the entrainment of high-temperature flue gas in the furnace within the pre-combustion chamber, thereby appropriately lowering the average temperature within the pre-combustion chamber and preventing premature ignition of the blended primary and secondary fuels, which could burn out the burner nozzles and cause ash and slag buildup on the walls of the pre-combustion chamber. Attached Figure Description

[0016] Figure 1 is a schematic diagram of the overall structure of the present invention.

[0017] Figure 2 is a schematic diagram of the first fuel primary air inlet of the present invention.

[0018] Explanation of reference numerals in the attached figures:

[0019] 1- Primary fuel primary air inlet; 2- DC inner secondary air duct; 3- Swirl vane; 4- Swirl outer secondary air duct; 5- Pre-combustion chamber; 6- Main fuel primary air inlet; 7- Secondary air swirl DC proportional adjustment baffle; 8- Secondary air duct; 9- DC secondary air vent.

[0020] 1-1- Annular uniform air distribution device; 1-2- Second fuel primary air inlet; 10- Main fuel primary air duct. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion regarding the concepts disclosed in the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0022] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0023] In the context of this invention, when a layer / element is referred to as being "above" another layer / element, the layer / element may be directly above the other layer / element, or there may be an intermediate layer / element between them. Furthermore, if a layer / element is "above" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "below" the other layer / element.

[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0025] The present invention will now be described in further detail with reference to the accompanying drawings:

[0026] Referring to Figures 1 and 2, the present invention provides a dual-fuel high-proportion co-firing swirl burner, comprising a primary fuel air duct 10, a primary fuel air inlet 6 and a first fuel air inlet 1 connected sequentially to the primary fuel air duct 10, a secondary air duct 8 fitted onto the primary fuel air duct 10, and a pre-combustion chamber 5 connected to both the primary fuel air duct 10 and the secondary air duct 8; the secondary air duct 8 is provided with a secondary air swirl DC proportional adjustment baffle 7, a DC inner secondary air duct 2 and a swirl outer secondary air duct 4, the swirl outer secondary air duct 4 is provided with a swirl vane 3, and the secondary air duct 8 is connected to the pre-combustion chamber 5 via a DC secondary air vent 9.

[0027] The first fuel primary air inlet 1 is divided into an annular uniform air distribution device 1-1 and a second fuel primary air inlet 1-2 that is uniformly arranged around the main fuel primary air duct 10. The second fuel primary air inlet 1-2 is connected to the outer edge of the main fuel primary air duct 10 and forms a tangential flow pattern at the four corners in the straight section of the main fuel primary air duct.

[0028] The cross-sections of the four secondary fuel primary air inlets 1-2 are perpendicular to the flow direction of the main fuel primary air duct.

[0029] A secondary air duct 8 is arranged around the primary air duct 10 of the main fuel. The secondary air duct 8 is further divided into a direct-flow inner secondary air duct 2 and a swirling outer secondary air duct 4. The direct-flow inner secondary air duct 2 is arranged close to the primary air duct of the main fuel, and the swirling outer secondary air duct 4 is arranged close to the direct-flow inner secondary air duct 2.

[0030] Both the DC internal secondary air duct 2 and the vortex external secondary air duct 4 are led out from the secondary air duct 8.

[0031] The secondary air duct 8 is equipped with a secondary air vortex DC ratio adjustment baffle 7. By adjusting the left and right opening of the secondary air vortex DC ratio adjustment baffle 7, the ratio of DC to vortex of the secondary air can be adjusted according to different mixing ratios, thereby achieving optimized combustion organization of the two fuels under different mixing ratios.

[0032] The principle and working process of this invention:

[0033] The dual-fuel, high-proportion co-firing swirl burner of this invention operates in the same way as a traditional swirl burner, where the primary air of the main fuel carries pulverized coal into the furnace. However, four secondary fuel primary air inlets 1-2 are arranged on the cross-section perpendicular to the flow direction of the primary fuel primary air, both inside and outside the horizontal primary fuel primary air duct. These four secondary fuel primary air inlets 1-2 are evenly distributed around the primary air duct, and their extensions form a tangent circle of radius R within the primary fuel primary air duct. This mimics the flow field organization of tangent-circle combustion, enhancing the mixing of the primary fuel and primary fuel primary air within the primary air duct. This results in a uniform mixture of the primary and secondary fuels before they enter the furnace. The radius R needs to be optimized based on the actual density difference between the primary and secondary fuels. By rationally setting the rotational momentum of the secondary fuel primary air, uniform mixing of the two fuels is achieved with minimal flow resistance. Secondly, after the fuel types and blending ratios of the primary and secondary fuels are determined, the ratio of direct and swirling secondary air entering the furnace can be adjusted by using a secondary air swirl-direct current ratio regulating baffle 7 installed in the secondary air duct 8. The optimal ratio of direct and swirling secondary air is selected based on the characteristics of the predetermined fuel types and blending ratios of the primary and secondary fuels. For example, for difficult-to-burn blended primary and secondary fuels, the flow rate of the swirling secondary air needs to be increased to enhance the entrainment of high-temperature flue gas in the furnace within the pre-combustion chamber 5, thereby increasing the average temperature within the pre-combustion chamber 5 and ensuring timely ignition of the blended primary and secondary fuels upon entering the pre-combustion chamber 5. Conversely, for easily flammable blended primary and secondary fuels, the flow rate of the swirling secondary air needs to be appropriately reduced, while the flow rate of the direct secondary air needs to be increased. This moderately weakens the entrainment of high-temperature flue gas in the furnace within the pre-combustion chamber 5, appropriately lowering the average temperature within the pre-combustion chamber 5, and preventing premature ignition of the blended primary and secondary fuels, which could burn the burner nozzles and cause ash and slag buildup on the walls of the pre-combustion chamber 5.

[0034] In summary, this invention can adapt to different fuel types and blending ratios of primary and secondary fuels. Under a wide range of fuel types and blending ratios, it can achieve uniform blending between the two fuels and optimize the combustion organization under the corresponding blending conditions. This ensures timely ignition of the difficult-to-burn blended primary and secondary fuels after they enter the pre-combustion chamber. For the easily flammable blended primary and secondary fuels, it appropriately weakens the high-temperature flue gas entrained in the furnace within the pre-combustion chamber and moderately reduces the average temperature within the pre-combustion chamber. This prevents premature ignition of the blended primary and secondary fuels, burning the burner nozzles, and preventing ash and slag buildup on the walls of the pre-combustion chamber. This enables safe, stable, efficient, and low-pollution operation of the boiler under a wide range of fuel types and blending ratios.

Claims

1. A dual-fuel, high-proportion co-firing swirl burner, characterized in that, It includes a primary fuel air duct (10), a primary fuel air inlet (6) and a first fuel air inlet (1) connected sequentially on the primary fuel air duct (10), a secondary air duct (8) fitted on the primary fuel air duct (10), and a pre-combustion chamber (5) connected to both the primary fuel air duct (10) and the secondary air duct (8); the secondary air duct (8) is provided with a secondary air vortex DC proportional adjustment baffle (7), a DC inner secondary air duct (2) and a vortex outer secondary air duct (4), and a vortex vane (3) is provided in the vortex outer secondary air duct (4); the first fuel air inlet (1) is divided into an annular uniform air distribution device (1-1) and a second fuel air inlet (1-2) evenly arranged around the primary fuel air duct (10), wherein the second fuel air inlet (1-2) is connected to the outer edge of the primary fuel air duct (10) and forms a four-corner tangential flow pattern in the straight section of the primary fuel air duct.

2. The dual-fuel high-proportion co-firing swirl burner according to claim 1, characterized in that, The cross-sections of the four secondary fuel primary air inlets (1-2) are perpendicular to the flow direction of the main fuel primary air duct (10).

3. A dual-fuel, high-proportion co-firing swirl burner according to claim 1, characterized in that, The secondary air duct (8) is divided into a direct current internal secondary air duct (2) and a vortex external secondary air duct (4).

4. A dual-fuel, high-proportion co-firing swirl burner according to claim 3, characterized in that, The DC inner secondary air duct (2) is arranged close to the main fuel primary air duct (10), and the vortex outer secondary air duct (4) is arranged close to the DC inner secondary air duct (2).

5. A dual-fuel, high-proportion co-firing swirl burner according to claim 3, characterized in that, The DC internal secondary air duct (2) and the vortex external secondary air duct (4) are both led out from the secondary air duct (8).

6. A dual-fuel, high-proportion co-firing swirl burner according to claim 3, characterized in that, The secondary air duct (8) is equipped with a secondary air vortex DC ratio adjustment baffle (7). By adjusting the left and right opening of the secondary air vortex DC ratio adjustment baffle (7), the ratio of DC to vortex of the secondary air is adjusted according to different mixing ratios, thereby achieving optimized combustion organization of the two fuels under different mixing ratios.

7. A dual-fuel, high-proportion co-firing swirl burner according to claim 1, characterized in that, The secondary air duct (8) is connected to the pre-combustion chamber (5) via the DC secondary air vent (9).

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