JP6060499B2 - Biomass mill - Google Patents

Description

  The present invention relates to a biomass mill for pulverizing wood-based biomass as boiler fuel, and more particularly to a biomass mill for pulverizing wood pellets.

At present, coal is mainly used as solid fuel for boilers, but as a measure for reducing CO ₂ , it is considered to use woody biomass that is renewable and has a low environmental impact as fuel.

  In order to use woody biomass as fuel for a boiler, it is necessary to grind woody biomass such as wood chips and wood pellets so that burner combustion is possible.

  When mixing woody biomass with coal to make fuel, it is possible to mix and pulverize with existing coal mills if the amount of woody biomass is small, but when the amount of woody biomass used increases, However, it is necessary to grind with woody biomass alone.

  In addition, a pulverization apparatus based on a coal roller mill for pulverizing coal as an apparatus for pulverizing woody biomass can be achieved at a low cost without significant improvements and major equipment changes.

  When coal is pulverized using a coal roller mill, lump coal is dropped from the coal supply device to the center of the pulverization table, the pulverization table is rotated by a table driving device, and the pulverization table rotates in the outer circumferential direction. The moved coal is pulverized by being caught in a pressure roller provided rotatably.

  The pulverized coal particles are further moved in the outer circumferential direction by the rotation of the pulverization table, blown upward by the primary air ejected at a high speed from the outlet, and fed to the burner from the pulverized coal pipe. .

  In the case of a conventional coal roller mill, the primary air outlet is provided in a circumferentially inclined manner around the grinding table so that the primary air is ejected from the circumference of the grinding table. The blown-up coal particles rise while swirling the classification chamber.

  However, when pulverizing woody biomass alone or when the mixing ratio of woody biomass to coal increases, the woody biomass is light and entangled with each other in the fiber, so that the rotation centrifugal force of the grinding table causes Movement to the outer periphery is not performed smoothly compared to coal.

  In addition, the woody biomass blown up to the primary air rises while swirling in the classification chamber, so the flow path becomes longer, making it difficult for the woody biomass to be discharged out of the mill, and it stays in the mill and stays in the mill. As a result, the blast power increases and the power of the table driving device increases. Due to an increase in the mill differential pressure and an increase in the power of the table driving device, the pulverization capacity of the woody biomass is limited to about 10% of the pulverization capacity of coal.

  As mentioned above, when woody biomass is supplied to a vertical mill or a mill with an equivalent structure and pulverized, the woody biomass behaves differently from coal, and sufficient pulverization efficiency and pulverization capacity are obtained. There was a problem that it was not possible.

  In Patent Document 1, a drift plate having a triangular cross section is provided on the inner surface of the casing above the air guide ring, and an air flow accompanied by a fine powder raw material is collided with the drift plate so that coarse particles are transferred onto the rotary table. A vertical roller mill that performs primary classification for dropping is disclosed.

JP 2007-209838 A

  In view of such circumstances, the present invention provides a biomass mill that promotes the discharge of woody biomass to the outside of the mill to increase the crushing capacity.

  The present invention includes a housing forming a classification chamber, a crushing table housed in a lower part of the housing and driven by a table driving device, and a plurality of pressure roller units having pressure rollers pressed against the crushing table. A blowout port for blowing primary air from the periphery of the pulverization table, a chute for supplying woody biomass to the center of the pulverization table, and a reduced flow tube covering the periphery of the chute, the reduced flow tube And a biomass mill in which a contracted flow path that reduces the cross-sectional area of the flow path of the primary air ejected from the outlet is formed between the housing and the housing.

  According to the present invention, the contracted flow cylinder has a cylindrical portion whose upper end is open, and a guide portion that extends between the pressure roller units while being inclined from the lower end of the cylindrical portion, and the guide portion and the housing Between the cylinder and an accelerating passage in which the cross-sectional area gradually decreases, and the contraction tube extends downward from the middle of the cylindrical portion toward the lower end of the chute. The present invention relates to a biomass mill that has a collection part having an inverted conical curved surface and in which an annular discharge port is formed between the lower end of the collection part and the chute.

  The present invention further includes a collecting umbrella provided so as to cover the upper end opening of the cylindrical portion, the collecting umbrella having a conical curved surface, and an annular shape between the collecting umbrella and the cylindrical portion. The present invention relates to a biomass mill in which a collection port is formed, and the lower end of the collection umbrella relates to a biomass mill located below the upper end of the cylindrical portion.

  Furthermore, the present invention further includes a chute support portion provided above the contracted flow tube and supporting the chute, and the chute support portion has an inverted conical curved surface that smoothly deflects the flow of primary air. It is related to.

  According to the present invention, a plurality of pressure rollers having a housing forming a classification chamber, a crushing table housed in a lower portion of the housing and driven by a table driving device, and a pressure roller pressed against the crushing table. A unit, a blow-off port for ejecting primary air from the periphery of the pulverization table, a chute for supplying woody biomass to the center of the pulverization table, and a reduced flow cylinder covering the periphery of the chute, A reduced flow path that reduces the cross-sectional area of the primary air jetted from the outlet is formed between the flow tube and the housing, so the flow rate of the primary air that rises up the classification chamber is increased. By reducing the time during which the pulverized wood biomass stays in the classification chamber, it is possible to promote the discharge of the pulverized wood biomass outside the mill, and to increase the pulverization capacity. It exhibits an excellent effect that it is.

1 is a schematic sectional elevation view of a vertical mill according to a first embodiment of the present invention. It is a schematic sectional elevation view of a vertical mill according to a second embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, referring to FIG. 1, a vertical mill 1 according to a first embodiment of the present invention will be described.

  A cylindrical housing 3 is erected on a base 2 having a hollow structure or a leg structure, and a sealed space is formed by the housing 3. A crushing table 5 is provided in the lower part of the space via a speed reducer 4, and the crushing table 5 is driven and rotated by a table drive motor 6 via the speed reducer 4. The crushing table 5 is rotated at a constant speed or a variable speed by the table driving motor 6, and the speed reducer 4 and the table driving motor 6 constitute a table driving device 7.

  A table segment 9 having a concave groove 8 having a circular arc cross section is provided on the upper surface of the pulverizing table 5, and the table segment 9 is connected in a ring shape. The rotational center of the pulverizing table 5 is formed by the concave groove 8. A ring-shaped pulverizing groove centering on is formed.

  A required number of, for example, three sets of pressure roller units 11 are provided radially from the rotation center of the crushing table 5 at intervals of 120 °. The pressure roller unit 11 has a pressure roller 12 and is tiltable about a pivot shaft 13. In addition, three sets of roller pressing devices 14 are provided below the housing 3 so as to penetrate the housing 3 radially. The roller pressure device 14 includes an actuator, for example, a hydraulic cylinder 15, and presses the pressure roller 12 against the concave groove 8 by the hydraulic cylinder 15.

  A primary air chamber 16 is formed below the grinding table 5, and a classification chamber 17 is located above the grinding table 5 inside the housing 3.

  A primary air supply port 18 is attached to the lower portion of the housing 3, and the primary air supply port 18 is connected to a blower (not shown) and communicates with the primary air chamber 16. Around the crushing table 5, primary air outlets 19 are provided on the entire circumference so that the primary air blows up along the inner wall of the housing 3. The outlet 19 is vertical or substantially vertical, or is inclined in the range of 0 ° to 5 ° in the central direction of the pulverizing table 5 and in the range of −5 ° to 0 ° in the rotational direction of the pulverizing table 5. You may form so that it may do.

  A fuel supply / discharge portion 20 is provided on the upper side of the housing 3, and a pipe-like chute 21 is provided so as to penetrate the central portion of the fuel supply / discharge portion 20. The chute 21 extends into the housing 3 and has a lower end located above the center of the crushing table 5. The chute 21 is supplied with woody biomass such as wood pellets, and the supplied wood pellets fall to the center of the crushing table 5.

  The chute 21 is provided with a contraction tube 22 so as to cover the lower part from the middle part of the chute 21. The contracted flow cylinder 22 has a hollow structure, and has a cylindrical cylindrical portion 24 with an open upper end, and extends downward from the lower end of the cylindrical portion 24 and at a predetermined angle toward the center of the classification chamber 17. The guide portion 25 has an inverted conical curved surface inclined at the bottom, and the guide portion 25 whose lower end is opened, and the inverted portion that extends from the middle portion of the cylindrical portion 24 toward the lower end of the chute 21 and gradually decreases in diameter downward. It is comprised from the collection part 27 which has a conical curved surface and the lower end was open | released. The upper end of the cylindrical portion 24 is supported by the chute 21 by a support member 23, and the collecting portion 27 is supported by the chute 21 by the support member 23.

  The cylindrical portion 24 has a diameter smaller than the inner diameter of the housing 3, and a cylindrical contracted flow path 28 is formed between the housing 3 and the cylindrical portion 24. The cross-sectional area of the contracted flow path 28 is not less than 1/15 times and not more than 1/10 times the cross-sectional area of the housing 3, and the flow rate of the primary air that rises up the contracted flow path 28 is reduced. Is about 10 times to 15 times.

  A plurality of notches 26 are formed in the guide portion 25 so as not to interfere with the pressure roller unit 11, and the guide portion 25 is prevented from contacting the pressure roller unit 11 by the notch portion 26. ing. That is, the guide portion 25 extends between the pressure roller units 11 and 11. Further, the guide portion 25 has a predetermined inclination angle, for example, the lower end is located inside the outer edge of the table segment 9, and the upper portion is interposed between the housing 3 and the guide portion 25. An accelerating channel 29 having a gradually decreasing cross-sectional area is formed. The acceleration channel 29 guides the primary air ejected from the outlet 19 to the contracted channel 28 while increasing the speed.

  The collecting part 27 has a lower end located in the vicinity of the lower end of the chute 21, and an inner diameter of the lower end of the collecting part 27 is larger than an outer diameter of the chute 21. A ring-shaped discharge port 31 having a predetermined width is formed between the chute 21 and the chute 21.

  A rotating tube 32 is fitted on the chute 21, and the rotating tube 32 is rotatably supported by a rotating tube support 33 via a bearing 34. The rotary pipe 32 is provided with a pulley 35, and a belt 37 is wound between the pulley 35 and the pulley 36. The pulley 36 is fitted to the output shaft of the speed reducer 38, A classifier motor 39 is connected to the machine 38. Thus, the rotary tube 32 is rotated by the classifier motor 39 via the speed reducer 38, the pulley 36, the belt 37, and the pulley 35.

  A blade 41 is attached to the rotary tube 32, and a classifier 42 is constituted by the rotary tube 32, the pulley 35, the pulley 36, the belt 37, the speed reducer 38, the classifier motor 39, and the blade 41. ing.

  The blades 41 have a strip shape and are arranged on the inverted conical curved surface at a predetermined angular pitch in the circumferential direction. The blade 41 is inclined from the lower end toward the upper end so as to be separated from the rotary tube 32, and is attached to the rotary tube 32 via a blade support portion 43.

  The fuel supply / discharge unit 20 is provided with a pulverized material supply pipe 44 for supplying pulverized wood pellets, and the pulverized material supply pipe 44 is connected to a burner (not shown) of a boiler. A pulverized material feed port 45 is formed at the base end of the pulverized material feed pipe 44, and the classification chamber 17 and the pulverized material feed pipe 44 communicate with each other through the pulverized material feed port 45. It has become.

  Next, the pulverization of wood pellets in the vertical mill 1 will be described. The wood pellet is an object in which wood flour such as sawdust is pressed to a diameter of 6 mm to 10 mm and a length L of 20 mm to 30 mm.

  In the figure, the solid line indicates the flow of primary air, and the dotted line indicates the flow of wood pellets.

  The pulverization table 5 is rotated by the table drive motor 6 via the speed reducer 4, and primary air at around 200 ° C. is introduced into the primary air chamber 16 from the primary air supply port 18. A wood pellet is introduced from the chute 21. The wood pellets flow down from the lower end of the chute 21 to the center of the crushing table 5 and are supplied onto the crushing table 5.

  The wood pellets on the crushing table 5 are moved in the outer peripheral direction by the centrifugal force generated by the rotation of the crushing table 5, and are pulverized by being caught by the pressure roller 12. The pulverized powder further moves to the outer periphery by centrifugal force.

  The primary air introduced into the primary air chamber 16 from the primary air supply port 18 is blown up vertically or substantially vertically from the blowout port 19 formed vertically or substantially vertically around the pulverization table 5. It is done. The powder that has passed over the table segment 9 due to the centrifugal force generated by the rotation of the pulverizing table 5 rides on the primary air blown up from the blow-out port 19, and becomes a powder flow as the inner wall side of the housing 3 by the guide portion 25. The accelerating flow path 29 is raised while being guided. Since the cross-sectional area of the acceleration channel 29 gradually decreases upward, the powder flow rising up the acceleration channel 29 is gradually contracted and increased as it rises.

  The powder flow increased in the process of passing through the acceleration flow path 29 flows into the contracted flow path 28. Since the cross-sectional area of the contracted flow channel 28 is small, the powder flow is further contracted and increased in the process of passing through the contracted flow channel 28.

  The powder flow that has passed through the contracted flow path 28 is decelerated due to an increase in the cross-sectional area of the flow path. The powder and unpulverized wood pellets blown to primary air separate from the powder stream.

  Further, after the gravity classification, the powder flow reaches the classifier 42, and the classifier 42 classifies the powder. Fine powder having a predetermined particle size or less flows into the classifier 42, is sent from the pulverized material feed pipe 44 through the pulverized material feed port 45, and is supplied to a burner of a boiler (not shown). The coarse powder and unground wood pellets are repelled by the blade 41, the coarse powder repelled by the blade 41, unground wood pellets, and the coarse powder separated from the powder stream by gravity classification, Unground wood pellets fall into the cylindrical portion 24.

  Since the primary air ejected from the outlet 19 is guided by the guide portion 25 and is blown upward without being blown into the contracted flow tube 22, the contracted flow The pressure inside the cylinder 22 is lower than the pressure around the classifier 42. Accordingly, a part of the primary air in the powder flow that has passed through the contracted flow channel 28 becomes a downward flow that descends inside the contracted flow cylinder 22, and the coarse powder that has fallen into the cylindrical portion 24 and the unflowed powder. The pulverized wood pellets fall with the descending flow, slide down the slope of the collecting portion 27, and fall onto the pulverizing table 5 through the discharge port 31. Furthermore, since the upward flow and the downward flow are separated by the cylindrical portion 24, it is possible to suppress the occurrence of pressure loss caused by the interference between the upward flow and the downward flow.

  At this time, the powder flow rises in the classification chamber 17 without swirling. Therefore, compared with the conventional vertical mill that has been swung up in the classification chamber 17, the powder flow from the outlet 19. Since the flow path to the pulverized material feed pipe 44 is shortened and the powder flow is increased in the process of passing through the acceleration flow path 29 and the contracted flow path 28, the powder flow rate is increased. The arrival time to the pulverized material feed pipe 44 is also shortened.

  The coarse powder and the unpulverized wood pellets that have been classified by the gravity and the classifier 42 are moved to the concave groove 8 by the rotational centrifugal force of the pulverizing table 5, and are pulverized again by the pressure roller 12. Blown up by primary air.

  As described above, in the first embodiment, between the cylindrical portion 24 of the contracted flow cylinder 22 and the housing 3, for example, 1/15 times or more and 1/10 times or less of the sectional area of the housing 3. Since the cylindrical contracted flow path 28 having a cross-sectional area is formed, the powder flow passing through the contracted flow path 28 is accelerated. That is, the time until the powder reaches the pulverized material feeding pipe 44 is shortened, the time during which the powder stays in the vertical mill 1 is shortened, and the powder is positively moved out of the vertical mill 1. Can be discharged, and the pulverization capacity can be increased.

  Further, since the guide portion 25 extending downward from the lower end of the cylindrical portion 24 is provided, the powder flow is smoothly increased in the process of passing through the acceleration flow path 29, and the powder is more positively activated. In addition, it can be discharged to the outside of the vertical mill 1, and the pressure loss when the powder flows from the acceleration flow path 29 to the contracted flow path 28 can be reduced, and the pulverization capacity can be further increased. it can.

  In addition, since the collecting portion 27 extending downward from the middle portion of the cylindrical portion 24 toward the lower end portion of the chute 21 is provided, coarse powder that has fallen into the cylindrical portion 24 after classification is not The pulverized wood pellet can be reliably dropped onto the center of the pulverization table 5.

  In addition, a downward flow of primary air is formed in the contracted flow tube 22 and the discharge port 31 is formed between the lower end of the collection part 27 and the chute 21 so that the cross-sectional area is reduced. Therefore, the primary air blown out from the blowout port 19 rises in the contracted flow tube 22 through the discharge port 31 and the blown-up powder stays in the classification chamber 17. Can be prevented.

  Further, by making the inclination of the blowout port 19 vertical or substantially vertical, the upward flow of the primary air ejected from the blowout port 19 is made vertical or substantially vertical, and the pulverized material feed pipe is fed from the blowout port 19. Since the flow path of the powder flow up to 44 is shortened, the time during which the powder stays in the vertical mill 1 can be shortened, and the grinding capacity can be increased.

  Next, referring to FIG. 2, a second embodiment of the present invention will be described. 2 that are the same as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

  In the vertical mill 1 in the second embodiment, the classifier 42 (see FIG. 1) in the first embodiment is omitted.

  The chute 21 for supplying the wood pellets onto the crushing table 5 is supported by a chute support 46 provided in the fuel supply / discharge unit 20. The chute support 46 has an inverted conical shape having an inverted conical curved surface that is inclined from the lower end toward the upper end so as to be separated from the chute 21, and the upper end is at the same position as the upper end of the pulverized material feed port 45. ing.

  A collecting umbrella 48 is provided so as to cover the upper end opening of the cylindrical portion 24 of the contracted flow tube 22, and the collecting umbrella 48 is supported by the chute 21 by a rod-shaped collecting umbrella support member 47. The collecting umbrella 48 has a truncated cone shape having a conical curved surface inclined from the upper end toward the lower end so as to be separated from the chute 21, and the lower end of the collecting umbrella 48 is more than the upper end of the cylindrical portion 24. Located below. That is, the lower end portion of the collecting umbrella 48 is accommodated in the cylindrical portion 24.

  The outer diameter of the collecting umbrella 48 is smaller than the inner diameter of the cylindrical portion 24, and a ring-shaped collecting port 49 having a predetermined width is provided between the collecting umbrella 48 and the cylindrical portion 24. It is formed.

  When the wood pellets are pulverized, the powder flow that has passed through the accelerating flow path 29 and the contracted flow path 28 is deflected by the chute support portion 46, and the outer periphery along the inclination of the chute support portion 46. While being guided in the direction, the crushed material is smoothly fed to the pulverized material feed port 45, and is fed from the pulverized material feed port 45 to the pulverized material feed pipe 44.

  Further, after passing through the contracted flow path 28, the powder separated from the powder flow by being decelerated and deflected slides down along the inclination of the collection umbrella 48 and passes through the collection port 49. It falls into the cylindrical portion 24 and falls to the center of the crushing table 5 through the discharge port 31.

  As described above, since the classifier 42 (see FIG. 1) is omitted in the second embodiment, the configuration of the vertical mill 1 can be simplified and the cost can be reduced.

  Further, the collecting umbrella 48 having a conical curved surface is provided so as to cover the upper end opening of the contracted flow cylinder 22, and the powder flow that has passed through the contracted flow path 28 is fed to the pulverized material feed pipe 44. In the process, the powder separated from the powder flow slides down on the collecting umbrella 48 and falls into the cylindrical portion 24. Therefore, the powder separated from the powder flow falls on the collecting umbrella 48. Can be prevented.

  Further, the lower end of the collecting umbrella 48 is positioned below the upper end of the cylindrical portion 24. That is, since the collection port 49 is located below the upper end of the contracted flow channel 28, the powder sliding down the collection umbrella 48 is again converted into the powder flow that has passed through the contracted flow channel 28. Without being blown up, it is possible to prevent an increase in the mill differential pressure due to the retention of the powder.

  Further, since the chute support portion 46 that supports the chute 21 has an inverted conical curved surface, the powder flow that has passed through the contracted flow channel 28 can be guided to the pulverized material feed pipe 44. It is possible to prevent the powder from staying above the collecting umbrella 48 and increasing the mill differential pressure.

DESCRIPTION OF SYMBOLS 1 Vertical mill 3 Housing 5 Crushing table 7 Table drive device 11 Pressure roller unit 12 Pressure roller 16 Primary air chamber 17 Classification chamber 19 Outlet 20 Fuel supply / discharge part 21 Chute 22 Shrinking cylinder 24 Cylindrical part 25 Guide part 27 Collection Portion 28 Shrinkage Flow Channel 29 Acceleration Flow Channel 31 Discharge Port 42 Classifier 46 Chute Support Portion 48 Collection Umbrella 49 Collection Port

Claims (4)

A housing forming a classification chamber, a crushing table housed in a lower portion of the housing and driven by a table driving device, a plurality of pressure roller units having pressure rollers pressed against the crushing table, and the crushing table A blowout port for blowing out primary air from the periphery, a chute for supplying woody biomass to the center of the crushing table, and a reduced flow tube covering the periphery of the chute, the upper end of the reduced flow tube being open And a notch that does not contact the pressure roller unit, and extends between the pressure roller units while inclining toward the center from the lower end of the cylinder, and the lower end is the crushing table. a guide portion positioned at the center side from the outer edge of, and a collecting portion having an extending out inverted cone curved downward toward the lower end of the chute from the intermediate portion of the cylindrical portion, before A contracted flow path is formed between the cylindrical portion and the housing to reduce a cross-sectional area of the primary air jetted from the blowout port, and gradually increases upward between the guide portion and the housing. An accelerating flow path having a reduced cross-sectional area is formed , an annular discharge port is formed between the lower end of the collecting portion and the lower end of the chute, and the primary air blown from the blow-out port is caused by the guide portion. A biomass mill configured to be guided to the acceleration flow path. A housing forming a classification chamber, a crushing table housed in a lower portion of the housing and driven by a table driving device, a plurality of pressure roller units having pressure rollers pressed against the crushing table, and the crushing table A blowout port for blowing out primary air from the periphery, a chute for supplying woody biomass to the center of the crushing table, and a reduced flow tube covering the periphery of the chute, the upper end of the reduced flow tube being open And a notch that does not contact the pressure roller unit, and extends between the pressure roller units while inclining toward the center from the lower end of the cylinder, and the lower end is the crushing table. of a guide portion positioned on the center side from the outer edge, and a trapping umbrella provided as to cover the upper end opening of the cylindrical portion has a conical curved surface, of the housing and the cylindrical portion An accelerating flow path in which a contracted flow path for reducing the flow path cross-sectional area of the primary air ejected from the outlet is formed, and the cross-sectional area gradually decreases upward between the guide portion and the housing. Is formed, and an annular collection port is formed between the collection umbrella and the cylindrical portion, and primary air ejected from the blowout port is guided to the acceleration flow path by the guide portion. A biomass mill characterized by that . The biomass mill according to claim 2 , wherein a lower end of the collecting umbrella is positioned below an upper end of the cylindrical portion. Wherein provided above the contraction flow tube further comprises a chute supporting portion supporting the chute, the chute support portion of claim 1 to claim 3 having an inverted conical curved surface to smoothly deflect the flow of primary air One of these biomass mills.

Images