Biomass fuel combustion system

Abstract

To provide a biomass fuel combustion system which is achieved in space saving, and excellent in combustion efficiency.SOLUTION: A biomass fuel combustion system 1 is substantially constituted of a combustor 2, a screw conveyor 3, and a storage tank 4. A rotating shaft of a screw 40 is formed into a conical shape having an air passage 45 at a center part, and continuously arranged at a hollow drive shaft having an air flow passage 46 which communicates with the air passage 45. A space 47 is formed between a tip of a screw casing 43 and a tip of the screw 40, and particulate matters transported by the screw 40 are mixed with compressed air which is injected through the air passage 45 and the air flow passage 46 in the space 47, and supplied to the combustor 2. The combustor 2, the screw 40 and the casing 43 are arranged in the storage tank 4. A notched hole is notched and formed at an upper part of the screw casing 43, and the particulate matters in the storage tank 4 are introduced to the screw 40 through the notched hole.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a system for burning biomass fuels, particularly particulate biomass fuels. [Background technology]

[0002] In recent years, there has been a demand for a shift to renewable energy sources from the perspective of environmental protection, and biomass fuels are a typical example of this. One type of biomass fuel is wood chips that have been finely pulverized into granular form. This is preferable because it does not require compression molding like wood pellets, does not require labor or cost, is dry, and burns completely, resulting in high combustion efficiency. The applicant has proposed various devices for burning such granular form.

[0003] For example, Patent Document 1 discloses a biomass energy production system that mixes powder and compressed air and sends them into a combustion chamber, where they can be completely combusted without the need for auxiliary fuel due to the swirling flow. Patent Document 2 discloses a screw conveyor that efficiently mixes powder and compressed air and supplies a fixed amount of two fluids into a combustor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2014-202362 [Patent Document 2] Patent application 2020-173610

[0005] However, when installing the screw conveyors in the biomass energy production system, a large space is required because each conveyor is placed separately, which makes it difficult to install the conveyors in small workshops or private homes. Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a biomass fuel combustion system that is excellent in combustion efficiency, requires as little space as possible, and can be installed in a variety of locations. [Means for solving the problem]

[0007] In order to solve the above problems, a first feature of the biomass fuel combustion system according to the present invention is a combustor having a plurality of combustion chambers for burning powdered or granular material that is a biomass fuel, a screw conveyor that sends the powdered or granular material to the combustor by a screw having blades, The combustor and the screw conveyor and a tank for storing powdered or granular material to be discharged. In the biomass fuel combustion system, the screw has a conical rotating shaft with an air passage penetrating through its center, and the rotating shaft is connected to a hollow drive shaft having an air flow path communicating with the air passage. The combustor comprises a cover and a combustion furnace body installed inside the cover, and a heat insulating material is filled between the cover and the combustion furnace body. and a space is formed between the tip of the casing of the screw and the tip of the screw, and the powdered material transported by the screw is mixed in the space with the compressed air ejected through the air flow path and the air passage, and is supplied to the combustor through a two-fluid supply pipe communicating with the space.

[0008] A second feature of the biomass fuel combustion system of the present invention is that, in the biomass fuel combustion system of the first feature, a cutout hole is formed in the upper part of the casing of the screw, and the combustor, the screw and the casing are arranged inside the storage tank, and the powdered material in the storage tank is introduced into the screw through the cutout hole.

[0009] Furthermore, a third feature of the biomass fuel combustion system of the present invention is that, in the biomass fuel combustion system of the first or second feature, the screw and the casing are arranged at the bottom of the storage tank.

[0010] Furthermore, a fourth feature of the biomass fuel combustion system of the present invention is that, in the biomass fuel combustion system of any one of the first to third features, the combustor has two combustion chambers, one combustion chamber has a two-fluid supply nozzle for supplying powdered material and compressed air and an auxiliary fuel supply nozzle for ignition, the two-fluid supply nozzle is connected to the screw conveyor via the two-fluid supply pipe, and the other combustion chamber has a compressed air supply nozzle.

[0011] A fifth feature of the biomass fuel combustion system according to the present invention is that in any one of the biomass fuel combustion systems according to the first to fourth features, the screw is formed in a conical shape having multiple blades.

[0012] Further, a sixth feature of the biomass fuel combustion system according to the present invention is the biomass fuel combustion system according to any one of the first to fifth features, further comprising: Axis The pitch of the blades facing each other in the linear direction increases toward the tip of the rotating shaft. Effect of the Invention

[0013] According to the present invention, by integrating the combustor, the transport means, and the storage facility, a biomass fuel combustion system can be constructed in the space required for the storage facility alone, making it possible to use the system in places where it was previously difficult to install a biomass fuel combustion system. This promotes the use of biomass fuel as a carbon-neutral fuel, and contributes to the realization of a decarbonized society.

[0014] In addition, the present invention uses a combustor that generates a swirling flow, which provides high combustion efficiency and enables complete combustion of biomass fuel. Meanwhile, by making the combustor structure simple, it is possible to reduce the number of parts, making inspection and operation easier, and enabling the combustor itself to be made smaller and lighter.

[0015] Furthermore, the present invention uses a screw conveyor that can simultaneously supply biomass fuel and compressed air, eliminating the need for a separate compressed air supply facility. Combined with the combustor, the entire biomass fuel combustion system can be made more compact, further reducing space and enabling a significant reduction in manufacturing costs. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic front view of a biomass fuel combustion system. [Diagram 2] FIG. 1 is a schematic explanatory diagram of a biomass fuel combustion system as viewed from the left side. [Diagram 3] FIG. 1 is a schematic front view of a biomass fuel combustion system. [Figure 4] FIG. 2 is a schematic explanatory diagram showing a screw as viewed from the front. [Diagram 5] FIG. 2 is a schematic explanatory diagram showing a screw as viewed from the front. BEST MODE FOR CARRYING OUT THEINVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described by way of example with reference to the accompanying drawings.

[0018] Figures 1 to 3 are explanatory diagrams showing the overall configuration of the biomass fuel combustion system, with Figure 1 showing the cross-sections of the storage layer, the screw casing, and the burner cover so that the screw of the screw conveyor in the storage layer and the configuration of the burner can be seen, Figure 2 showing the cross-sections of the storage layer and the burner cover so that the configuration of the burner in the storage layer can be seen, and Figure 3 showing the cross-section of the screw in Figure 1 and the state in which biomass fuel is stored in the storage tank. Figures 4 and 5 show the screw, with Figure 4 showing the cross-section of the screw casing and Figure 5 showing the notched holes in the screw casing.

[0019] In the figure, reference numeral 1 denotes a powder combustion system, which is roughly composed of a combustor 2, a screw conveyor 3, and a storage tank 4, and the combustor 2 and the screw of the screw conveyor 3 are disposed inside the storage tank 4.

[0020] The combustor 2 is roughly composed of a cylindrical iron cover 11 and a cylindrical combustion furnace body 20 installed inside the cover 11. The cover 11 is provided to ensure safety by absorbing heat generated from the combustion furnace body 20, and a heat insulating material 12 is filled between the cover 11 and the combustion furnace body 20. The combustor 2 is fixed to the wall surface 60 of the storage tank 4 via lids 13 and 14 on both ends of the cover 11.

[0021] The combustion furnace body 20 burns biomass fuel inside while swirling it with compressed air to generate high-temperature heat energy, and its peripheral walls are made of refractory materials such as firebricks. The combustion furnace body 20 is also provided with an orifice 21 at the approximate middle of its cylindrical length, and is divided by the orifice 21 into a first combustion chamber 22 and a second combustion chamber 23 which communicate with each other.

[0022] In addition, a window 14 through which the state inside the first combustion chamber 22 can be seen is formed by blocking the tip of a sight glass pipe 15 that communicates with the first combustion chamber 22 and extends outside the storage tank 4 with a removable transparent acrylic plate 17.

[0023] Through holes 24, 25 are drilled in the peripheral wall of the first combustion chamber 22 in the tangential direction of the inner peripheral wall of the first combustion chamber 22, and a two-fluid supply nozzle 26 that sprays fuel-mixed air (two fluids) in which biomass powder fuel and compressed air are mixed is inserted into the through hole 24. An auxiliary fuel supply nozzle 27 that sprays auxiliary fuel is inserted into the through hole 25. An ignition device (not shown) is attached to the tip of the auxiliary fuel supply nozzle 27, and an ignition flame is sprayed from the tip. It is also possible to directly ignite the auxiliary fuel using an external ignition device without providing an ignition device at the tip of the auxiliary fuel supply nozzle 27.

[0024] In addition, a through hole 28 is drilled in the peripheral wall of the second combustion chamber 23 in the tangent direction of the inner peripheral wall of the first combustion chamber 22, and a compressed air supply nozzle 29 that sprays compressed air is inserted into the through hole 28.

[0025] The auxiliary fuel supply nozzle 27 is connected to an auxiliary fuel supply source (not shown) through an auxiliary fuel supply pipe 30. The auxiliary fuel is preferably propane gas or the like. The compressed air supply nozzle 29 is connected to a compressed air supply source (not shown) through a compressed air supply pipe 31.

[0026] The second combustion chamber 23 is connected to a horizontal cylindrical sleeve 30 that sends out the thermal energy generated within the combustion chamber to the outside, and the thermal energy is sent to other heat exchangers, boilers, and other devices that require thermal energy.

[0027] The screw conveyor 3 is roughly composed of a conical screw 40 having two helical blades 42a, 42b on the surface of a conically formed rotating shaft 41, a screw casing 43 formed in an approximately conical shape according to the shape of the screw 40 and having a notched hole 50 on the upper part of the surface, and a drive shaft 44 for rotating the screw 40.

[0028] The screw 40 is made of a metal such as iron, or a resin. The screw 40 has an air passage 45 that passes through the center of the rotating shaft 41. The drive shaft 44 has an air flow passage 46 that passes through the center of the drive shaft 44 and is formed hollow. The tip of the drive shaft 44 is inserted into the rear end of the center of the rotating shaft 41, and the air flow passage 46 communicates with the air passage 45. The air flow passage 46 is formed to have a slightly larger diameter than the air passage 45. This is to increase the pressure of the compressed air toward the tip of the screw 40.

[0029] In the figure, reference numeral 5 denotes a motor, the driving force of which is transmitted to the rear end of a drive shaft 44 by a transmission mechanism, causing the drive shaft 44 to rotate. Reference numeral 6 denotes a compressed air inlet pipe which communicates with an air flow path 46, and is connected to the rear end of the drive shaft 44 via a rotary joint 7. The compressed air inlet pipe 6 is connected to a fluid supply source (not shown) such as a compressor, and guides compressed air supplied from the fluid supply source into the air flow path 46 of the drive shaft 44. Reference numeral 8 denotes a bearing which supports the rear end of the drive shaft.

[0030] In this embodiment, two blades are formed on the surface of the rotating shaft 41. That is, the screw 40 is provided with blades 42a from the rear end to the tip of the rotating shaft 41, and blades 42b from the middle of the rotating shaft 41, slightly toward the rear end, to the tip. By providing two blades on the screw, it is possible to transport twice as much material as with a single blade. The blades can be multiple, such as two, three, or four, or may be single.

[0031] The vertical length of the two blades 42a, 42b becomes shorter toward the tip of the rotating shaft 41, and the angle of the blade with respect to the longitudinal direction (horizontal direction) of the rotating shaft 41 becomes smaller toward the tip. In other words, the angle θ1 of the blade near the tip of the rotating shaft 41 is smaller than the angle θ2 of the blade closer to the rear end.

[0032] Furthermore, the pitch of each of the blades 42a, 42b facing each other in the longitudinal direction of the rotating shaft 41 increases toward the tip of the rotating shaft 41. That is, in the illustrated example, the pitch P1 of the blades closer to the tip of the rotating shaft 41 is larger than the pitch P2 of the blades closer to the rear end.

[0033] The screw 40 has a so-called cone shape, and the casing 43 is formed in a cone shape with a diameter decreasing toward the tip of the casing 43 along the cone shape of the screw 40. That is, the diameter of the casing 43 is formed along the vertical length of the blades 42a, 42b. A space 47 is formed between the tip of the casing 43 and the tip of the screw 40, and a male thread is formed at the tip of the casing 43, and a screw block 49 is fastened to the male thread and connects a dual-fluid supply pipe 48 to the casing 43. The tip of the dual-fluid supply pipe 48 is connected in communication with the dual-fluid supply nozzle 26.

[0034] A substantially elliptical cutout hole 50 is formed in the upper part of the casing 43 for introducing biomass fuel into the screw 40. A flange 51 is formed in the rear end of the casing 43 for fixing the screw 40 to the storage tank 4. The rear end of the casing 43 is airtightly closed by a lid 52 through which the drive shaft 44 passes in the center, preventing the powdered biomass fuel from leaking to the outside. 53 is a fixing member for fixing the screw 40 to the storage tank 4 while supporting the drive shaft 44. The screw 40 is inserted into the storage tank 4 through a hole formed in the lower part of the wall surface 60 of the storage tank 4, and is fixed to the storage tank 4 through the fixing member 53, the lid 52, and the flange 51 by fastening means such as bolts.

[0035] The screw 40 is formed so that the pitch between each blade increases toward the tip, so that the amount of material that can be brought into the rear end of the screw 40 can be transported directly to the tip of the screw. If the screw has two blades, this can double the transport amount, thereby improving the transport efficiency.

[0036] The storage tank 4 is formed in a box shape, and houses the combustor 2, the screw 40, and its casing portion. The screw 40 and its casing portion are disposed below the combustor 2. A flange 61 is formed on the upper portion of the storage tank 4 so that it can be connected to other equipment.

[0037] In the figure, the area marked with many black dots in the storage tank 4 indicates biomass fuel made by pulverizing wood chips, wood chips, pallets, stalks, rice straw, etc. into powder form. The biomass fuel is supplied to the screw 40 through a notch 50 formed in the upper part of the casing 43 by its own weight, and is sent to the tip of the screw 40 by the rotation of the screw 40. In addition, compressed air is supplied from the fluid inlet pipe 6 through the air flow path 46 of the drive shaft 44, then into the air passage 45 of the screw 40, and is ejected from the tip of the rotating shaft 41. The biomass fuel transported to the tip of the screw 40 is mixed with the compressed air ejected from the tip of the rotating shaft 41 in the space 47 formed at the tip of the rotating shaft 41, and is supplied to the combustor 2 via the two-fluid supply pipe 48 and the two-fluid supply nozzle 26 connected to the tip of the casing 43 on the compressed air. This allows the biomass fuel to be continuously sent out of the screw 40 by compressed air, so that the biomass fuel does not remain on the screw 40 or become clogged.

[0038] The two fluids, biomass fuel and compressed air, ejected from the two fluid supply nozzle 26 into the first combustion chamber 22 swirl along the inner wall of the first combustion chamber 22, and the two fluids are also ignited by the flame ignited by the gas ejected from the auxiliary fuel supply nozzle 27, and the biomass fuel burns efficiently due to the swirling flow. After the biomass fuel is ignited, the flame supplied by the auxiliary fuel supply nozzle 27 is no longer necessary because the biomass fuel combusts spontaneously, and the flame is extinguished by stopping the gas supply.

[0039] The swirling flame that ignites the biomass fuel is narrowed by the orifice 21 provided in the combustion furnace body 20, increasing the flow rate, and moves to the second combustion chamber 23 while increasing the combustion power, where it is swirled by the compressed air supplied from the compressed air supply nozzle 29, increasing the combustion efficiency, and reaches a high temperature of over 1500 degrees. In this process, the biomass fuel is completely combusted.

[0040] Thermal energy generated within the furnace body 20 is transferred through the sleeve 30 to a thermal power engine, such as a boiler, directly or indirectly connected to the sleeve 30 .

[0041] The above describes the embodiment of the present invention through examples, but the present invention is not necessarily limited to the above-mentioned examples, and can be modified and implemented as appropriate within the scope of the claims. [Industrial Applicability]

[0042] The biomass fuel combustion system according to the present invention is suitable for heating facilities such as vinyl greenhouses, factories, hot springs, and public baths. It can also be used for heating private homes, particularly in cold regions, for floor heating, etc. Furthermore, it can be applied to facilities that generate steam using thermal energy and use the steam. [Explanation of symbols]

[0043] 1. Biomass fuel combustion system 2. Combustor 3. Screw conveyor 4. Storage tank 22 First Combustion Chamber 23 Second Combustion Chamber 26 Two-fluid nozzle 27 Auxiliary fuel supply nozzle 29 Compressed air supply nozzle 40 Screw 41 Rotation axis 42a, 42b Feather 43 Screw casing 44 Drive shaft 45 Air passage 46 Air Flow Path 50 Notch hole

Claims

1. A biomass fuel combustion system including a combustor having a plurality of combustion chambers for burning powdered or granular material that is a biomass fuel, a screw conveyor that delivers the powdered or granular material to the combustor by a screw having blades, and a tank that stores the powdered or granular material to be delivered to the combustor and the screw conveyor, The screw has a conical rotation shaft with an air passage at its center. the rotating shaft is connected to a hollow drive shaft having an air flow passage communicating with the air passage; The combustor comprises a cover and a combustion furnace body installed inside the cover, and a heat insulating material is filled between the cover and the combustion furnace body. the combustor, the screw, and the casing of the screw are each disposed inside the storage tank; A notch hole is formed in the upper part of the casing of the screw, and the powder in the storage tank is introduced into the screw through the notch hole; a space is formed between a tip of a casing of the screw and a tip of the screw, and the powder or granular material transported by the screw is mixed in the space with compressed air ejected through the air flow path and the air passage, and is supplied to the combustor through a two-fluid supply pipe communicating with the space; A biomass fuel combustion system comprising:

2. The screw and the casing are disposed at the bottom of the storage tank; 2. The biomass fuel combustion system according to claim 1 .

3. The combustion furnace body has two combustion chambers, one of which has a two-fluid supply nozzle for supplying powder and compressed air and an auxiliary fuel supply nozzle for ignition, and the two-fluid supply nozzle is connected to the screw conveyor via the two-fluid supply pipe; and the other combustion chamber is equipped with a compressed air supply nozzle; 2. The biomass fuel combustion system according to claim 1 .

4. The screw is formed in a conical shape having multiple blades; 2. The biomass fuel combustion system according to claim 1 .

5. the pitch of the blades facing each other in the axial direction of the rotating shaft increases toward the tip end of the rotating shaft; 2. The biomass fuel combustion system according to claim 1 .

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