JP6500066B2 - Biomass mill - Google Patents

Description

  The present invention relates to a biomass mill that pulverizes woody biomass to produce biomass particles that can be used as boiler fuel.

  In recent years, as this kind of biomass mill, a housing forming a classification chamber, a classifier provided at the upper part of the classification chamber, a grinding table provided at the lower part of the classification chamber and driven by a table driving device, A plurality of pressure roller units having pressure rollers pressed against the pulverization table; a blow-out port for ejecting primary air from the periphery of the pulverization table; and a chute for supplying woody biomass to the center of the pulverization table; A flow-reducing portion, and the flow-reducing portion includes an inner flow-reducing portion surrounding the chute and an outer current-reducing portion provided at a position facing the inner flow-reducing portion on the inner peripheral surface of the housing. A truncated conical part in which a contracted flow path is formed between the inner contracted part and the outer contracted part, and the inner contracted part extends above the upper end of the contracted flow path; Extends downward from the upper end of the truncated cone Having a inverted truncated cone section which has been proposed (e.g., see Patent Document 1.).

  According to Patent Document 1, since the conventional biomass mill is configured as described above, the powder in the classification chamber is increased by increasing the powder flow of the woody biomass through the contraction section. Retention time is reduced, the increase in the mill differential pressure is suppressed, the pulverization capacity is increased, and the accumulation of powder on the inner constricted part is prevented, and the powder is prevented from remaining in the classification chamber. It is said that safety can be improved. According to Patent Document 1, it is said that the biomass mill can be implemented at a low cost without significant improvement or equipment change by using a pulverizer based on a coal mill for pulverizing coal.

JP 2017-47383 A

  However, in the conventional biomass mill, a contracted portion having a contracted flow path capable of passing only biomass particles pulverized to a size of about 1 to 2 mm is formed between the pulverization table and the classifier. For large-sized coarse particles and woody biomass blown up with primary air without being crushed, it is made to collide with the lower surface of the reduced flow part, separate from the powder flow, and drop again onto the crushing table; It has become.

  For this reason, the conventional biomass mill tends to accumulate a large amount of woody biomass on the grinding table, it is difficult to efficiently produce the target biomass particles, and the pressure loss in the mill and the grinding power of the woody biomass are also low. Easy to increase. Moreover, since the conventional biomass mill tends to accumulate a large amount of woody biomass on the pulverization table, the volatile components contained in the woody biomass tend to be high in the mill, and there is a risk of ignition in the mill. Therefore, the conventional biomass mill has room for further improvement in these respects.

  Therefore, an object of the present invention is to provide a biomass mill capable of pulverizing woody biomass with high efficiency and safety.

  In order to achieve the above object, a representative present invention includes a rotary table disposed in a lower part of a housing, a grinding roller for pulverizing woody biomass between the rotary table, the rotary table, and the housing. A primary air outlet, a center chute for supplying woody biomass as a raw material to the center of the upper surface of the rotary table, a rotary classifier disposed at the top of the housing, and the housing The rotary classifier is configured by a cylindrical inner wall disposed inside the housing, an inner surface of the housing and an outer surface of the inner wall, and a powder flow blown up by primary air injected from the outlet An annular flow path for guiding the coarse particles of the woody biomass that has not passed through the rotary classifier to the annular flow path. Characterized in that it is configured to return only.

  According to the present invention, the biomass particles pulverized between the rotary table and the pulverizing roller can be efficiently discharged out of the mill, and the pressure loss in the mill and the pulverization power of the woody biomass can be suppressed. Woody biomass can be crushed safely. Problems, configurations, and effects other than those described above will become apparent from the description of the embodiments described below.

It is sectional drawing which shows the whole structure of the vertical biomass mill which concerns on embodiment. It is a perspective view which shows the principal part of the vertical biomass mill which concerns on embodiment. It is a perspective view which shows the structure of the internal wall with which the vertical biomass mill which concerns on embodiment is equipped. It is a graph which shows the grinding | pulverization motive power value of the vertical biomass mill which concerns on embodiment by a relative value with a prior art. It is a graph which shows the pressure loss value of the vertical biomass mill which concerns on embodiment by a relative value with a prior art. It is a graph which compares and shows the grinding | pulverization motive power characteristic and pressure loss characteristic with respect to the biomass supply load of the vertical type biomass mill which concerns on embodiment, and a prior art.

  Hereinafter, an embodiment of a biomass mill according to the present invention will be described using a vertical biomass mill as an example. In addition, embodiment described below shows a specific example at the time of implementing this invention, Comprising: The range of this invention is not restrict | limited to embodiment described below. In addition, pulverizing woody biomass, particularly wood pellets, to obtain biomass particles is generally referred to as “pulverization”, but in the present specification, it is referred to as “pulverization” following the example of a coal mill.

  FIG. 1 is a cross-sectional view showing the overall configuration of a vertical biomass mill according to an embodiment. As is apparent from this figure, the vertical biomass mill 1 according to the embodiment has a woody biomass as a raw material between the rotary table 3 that is rotationally driven in a horizontal plane by the table driving device 2 and the rotary table 3. A crushing roller 4 for crushing and producing biomass particles as a target product, a center chute 5 disposed above the turntable 3 and supplying woody biomass to the center of the upper surface of the turntable 3, and an outer periphery of the center chute 5 A rotating classifier 6 disposed on the outer periphery of the rotating classifier 6, a fixed classifier 7 disposed on the outer periphery of the rotating classifier 6, a bounce plate 8 disposed further on the outer periphery of the fixed classifier 7, the rotating classifier 6 and the fixed classifier. And a distribution unit 9 that conveys the biomass particles classified in 7 to a predetermined supply destination.

  The rotary table 3, the grinding roller 4, the rotary classifier 6, and the fixed classifier 7 are accommodated in a cylindrical housing 11, and the upper end of the housing 11 is connected to the distributor 9. . Further, between the crushing roller 4 and the rotary classifier 6, an inner wall 12 that prevents the return of coarse particles from the rotary classifier 6 and the fixed classifier 7 to the rotary table 3 is disposed concentrically with the housing 11. ing. As a result, an annular flow path 13 that is a flow path of the powder flow containing biomass particles is formed between the inner surface of the housing 11 and the outer surface of the inner wall 12.

  Between the outer peripheral surface of the turntable 3 and the inner surface of the housing 11, a primary air outlet 15 having a rotary throat vane 14 is provided. The primary air is supplied from the primary air duct 16, the flow velocity and the wind direction are adjusted by the rotary throat vane 14, and are injected into the housing 11 from the blowout port 15. In the vertical biomass mill 1, the primary air temperature is adjusted to, for example, 150 ° C., which is lower than that of the coal mill.

  On the upper surface of the rotary table 3, a ring-shaped concave groove 3 a having a width capable of receiving the grinding roller 4 is formed concentrically with the rotation center of the rotary table 3. Therefore, when the rotary table 3 is rotationally driven by the table driving device 2, the crushing roller 4 rolls in the concave groove 3a, whereby the woody biomass as the raw material is pulverized to produce the biomass particles as the target product. The

  Various types of woody biomass can be used, but since wood particles having a uniform size of about 1 mm to 2 mm can be obtained by pulverization, woody pellets obtained by pressing wood powder into pellets. Is particularly preferred.

  The grinding roller 4 is rotatably attached to a roller bracket 21, and the roller bracket 21 is supported by a pressure frame 23 via a roller pivot 22. Further, the pressure frame 23 is connected to a pressure rod 26 of a pressure cylinder 25 having one end connected to a predetermined fixing portion via a pressure arm 24. Accordingly, the crushing roller 4 is moved up and down via the pressure rod 26, the pressure arm 24, the pressure frame 23, the roller pivot 22, and the roller bracket 21 by driving the pressure cylinder 25, The grinding load acting between the rotary table 3 and the grinding roller 4 is adjusted. A plurality of crushing rollers 4 are provided in the circumferential direction of the rotary table 3 (in many cases, three).

  In addition, the aspect of the above-mentioned grinding | pulverization is an example, Comprising: This invention is not limited to this. The form of the pulverizer is not limited to a roller shape, but may be a ball shape. If the crusher is pushed down and the crushing load acts on the concave groove 3a, such as the rotating shaft of the roller, the components and the operation of each element are not limited.

  The center chute 5 has an upper end portion attached to the distribution portion 9 and a lower end portion inserted into the inner wall 12.

  The rotary classifier 6 is configured by arranging a large number of fins 6a at predetermined intervals in the circumferential direction, and classifying biomass particles by rotationally driving these fins 6a with a motor (not shown). It is like that. The particle size distribution of the biomass particles is adjusted by the rotational speed of the fins 6a. In the rotary classifier 6 according to the embodiment, the bottom plate is a fin support annular plate 6b for standing the fins 6a. The rotary classifier 6 has a function of evenly distributing the biomass particles to each of a plurality of (only one is shown in FIG. 1) transport pipes 9a provided in the distribution unit 9.

  The fixed classifier 7 includes a large number of non-rotating fins arranged in a circumferential direction at a predetermined interval, and classifies biomass particles in the powder flow by applying the powder flow to the fins.

  The rebound plate 8 repels biomass particles that have blown up through the annular flow path 13 and above the rotary classifier 6 and the fixed classifier 7 and leads them to the rotary classifier 6 and the fixed classifier 7. It also functions as a contraction member for adjusting the flow velocity of the powder flow flowing into the machine 6 and the fixed classifier 7. The rebound plate 8 adjusts the flow rate of the powder flow flowing into the rotary classifier 6 and the fixed classifier 7 to, for example, about 10 m / sec.

  The distribution unit 9 is provided with a transport pipe 9a that transports biomass particles produced by the vertical biomass mill 1 to a predetermined transport destination. As a transfer destination of the biomass particles, there is a biomass-fired boiler or a biomass-fired boiler that co-fires woody biomass and coal. In addition, when the distribution part 9 is provided with the some conveyance pipe | tube 9a, the structure which makes the edge part of the conveyance pipe | tube 9a protrude in the distribution part 9 in order to equalize introduction | transduction of the biomass particle | grain into each conveyance pipe | tube 9a. It can also be.

  The housing 11 is formed in a cylindrical shape that can accommodate the rotary table 3, the crushing roller 4, the rotary classifier 6, the fixed classifier 7, and the rebound plate 8. To facilitate maintenance of the vertical biomass mill 1, For example, it can also be configured with a combination of a plurality of members that can be disassembled, such as being composed of three members, an upper housing, a middle housing, and a lower housing.

  As shown in FIGS. 2 and 3, the inner wall 12 extends downward from a ring member 31 disposed opposite to the fin support annular plate 6 b of the rotary classifier 6 and an upper end portion to which the ring member 31 is attached. Accordingly, the upper conical portion 32 having a large diameter, a cylindrical portion 33 connected to the lower end portion of the upper conical portion 32, and a plurality of detachable plates 34 detachably connected to the lower end portion of the cylindrical portion 33 are configured. ing.

  As shown in FIG. 1, the inner wall 12 is disposed between the rotary table 3 and the rotary classifier 6 inside the housing 11. The inner wall 12 is attached to the housing 11 using a fixing member (not shown) extending from the inner surface of the housing 11. A slight clearance d is provided between the fin support annular plate 6 b and the ring member 31 in order to prevent interference between the rotary classifier 6 and the inner wall 12. The size of the clearance d is set to about 2 mm to 8 mm in order to keep the flow path resistance of the flow path from the inner side to the outer side of the inner wall 12 large. Thereby, the penetration | invasion of the biomass particle | grains between the fin support annular plate 6b and the ring member 31 can be prevented, and the fin support annular plate 6b and the ring member 31 by a biomass particle can be prevented from galling.

  In the cylindrical portion 33, a pressure arm through hole 35 for penetrating the pressure arm 24 is opened, and a maintenance door 36 for enabling loading and unloading of the grinding roller 4 during maintenance can be opened and closed. Provided. As described above, by opening the pressure arm through hole 35 in the cylindrical portion 33, the inner wall 12 can be installed in the housing 11. Further, by providing the cylindrical portion 33 with the maintenance door 36, the grinding roller 4 can be replaced during maintenance.

  The detachable plate 34 is attached to the cylindrical portion 33 after the pressurizing arm 24 penetrates into the pressurizing arm through hole 35, and an access door 37 through which a person enters and exits during maintenance is opened and closed. It is possible. As described above, the cylindrical wall 33 and the detachable plate 34 are configured as separate members, so that the inner wall 12 can be installed in the housing 11. Further, by providing the access door 37 on the detachable plate 34, it is possible for an operator to enter the vertical biomass mill 1 and to perform maintenance on the grinding roller 4 and the like.

  The desorption plate 34 has a function of guiding the biomass particles blown up by the primary air into the annular flow path 13. For this reason, the detaching plate 34 is disposed on the outer peripheral side of the crushing roller 4 so as to overlap at least a part of the crushing roller 4, and more preferably, the lower end part covers the lower part than the rotation center of the crushing roller 4. Configured as follows.

  Hereinafter, the operation and effect of the biomass mill 1 according to the embodiment configured as described above will be described.

  The woody biomass A supplied from the center chute 5, as indicated by an arrow in FIG. 1, falls on the center of the turntable 3 and then spirals on the turntable 3 due to the centrifugal force accompanying the rotation of the turntable 3. The trajectory is drawn and moved to the outer peripheral portion and enters the concave groove 3a. The woody biomass A that has entered the groove 3a is caught between the rotary table 3 and the tire-like crushing roller 4 and pulverized into biomass particles.

  The generated biomass particles are blown upward while being dried by the primary air blown into the housing 11 from the blowout port 15, and are introduced into the annular flow path 13 as a powder flow B containing biomass particles. The The powder flow B moves upward while spirally rotating in the annular flow path 13, and moves along the flow path along the upper conical portion 32 provided on the inner wall 12 on the rotary classifier 6 and fixed classifier 7 side. Change to

  Among the biomass particles that have passed through the annular flow path 13, those having an appropriate size enter the distribution unit 9 through the direct rotary classifier 6 or the fixed classifier 7. Further, among the biomass particles that have passed through the annular flow path 13, the fine particles strike the bounce plate 8 and then enter the distribution unit 9 through the rotary classifier 6 or the fixed classifier 7. On the other hand, of the biomass particles that have passed through the annular flow path 13, the coarse particles C cannot pass through the rotary classifier 6 or the fixed classifier 7, and are guided to the upper cone portion 32 provided in the inner wall 12, and again. Return to the annular flow path 13.

  The coarse particles that have returned to the annular flow path 13 move up and down in the annular flow path 13 due to the balance between their own weight and the blowing force of the primary air, and are finely pulverized therebetween. It enters the distribution unit 9 through the classifier 7. That is, the annular flow path 13 functions as a biomass particle gravity classifier.

  Thus, the vertical biomass mill 1 according to the embodiment includes the inner wall 12 between the rotary table 3 and the rotary classifier 6, and the coarse particles C that have not passed through the rotary classifier 6 or the fixed classifier 7. Is returned to the annular flow path 13 formed between the inner surface of the housing 11 and the outer surface of the inner wall 12, so that the coarse particles C can be prevented from returning onto the turntable 3. That is, the vertical biomass mill 1 according to the embodiment has a one-through structure in which biomass particles pulverized between the rotary table 3 and the pulverizing roller 4 are discharged only to the distribution unit 9 side through the annular flow path 13. Therefore, the return of the coarse particles C onto the turntable 3 can be reliably prevented.

  Therefore, according to the vertical biomass mill 1 according to the embodiment, the woody biomass A exceeding the preset amount does not stay on the turntable 3, so that the power required for pulverizing the woody biomass can be suppressed, and the mill The pressure loss inside can also be suppressed. Furthermore, according to the vertical biomass mill 1 according to the embodiment, an increase in the concentration of volatile components in the mill can be prevented.

  In FIG. 4, the grinding | pulverization motive power value of the vertical biomass mill 1 which concerns on embodiment is shown compared with the conventional vertical biomass mill which does not provide the internal wall 12. FIG. In this graph, the grinding power value of the vertical biomass mill 1 according to the embodiment is shown as a relative value when the grinding power value of the conventional vertical biomass mill is “1”. In the conventional vertical biomass mill, a large amount of woody biomass A tends to stay on the turntable 3, and if a large amount of woody biomass A stays on the turntable 3, the pulverization power increases rapidly. Is difficult to raise. Therefore, in FIG. 4, it is a comparison at a low load operation that can be compared.

  The pulverization power varies greatly depending on the type of woody biomass that is the raw material and the operating conditions of the mill, but according to the data in FIG. 4, the pulverization power value of the vertical biomass mill 1 according to the embodiment is the conventional vertical type. It is 0.42 to 0.63 times the grinding power value of the biomass mill. From this data, it can be said that the vertical biomass mill 1 which concerns on embodiment can suppress a grinding | pulverization power markedly compared with the conventional vertical biomass mill.

  In FIG. 5, the pressure loss value of the vertical biomass mill 1 which concerns on embodiment is shown compared with the conventional vertical biomass mill which does not have the internal wall 12. FIG. This graph also shows the pressure loss value of the vertical biomass mill 1 according to the embodiment as a relative value when the pressure loss value of the conventional vertical biomass mill is “1”. Moreover, it is a comparison at the time of low load operation that can be compared.

  The pressure loss in the mill also varies greatly depending on the type of woody biomass that is the raw material and the operation conditions of the mill, but according to the data in FIG. 5, the pressure loss value of the vertical biomass mill 1 according to the embodiment is conventionally It is 0.37-0.67 times the pressure loss value of the vertical type biomass mill. From this data, it can be said that the vertical biomass mill 1 which concerns on embodiment can suppress a pressure loss markedly compared with the conventional vertical biomass mill.

  In FIG. 6, the pulverization power characteristic and the pressure loss characteristic with respect to biomass supply load of the vertical biomass mill 1 according to the embodiment and the conventional vertical biomass mill not provided with the inner wall 12 are compared and shown. As is apparent from this data, the vertical biomass mill 1 according to the embodiment has stable pulverization power characteristics and pressure loss characteristics against fluctuations in biomass supply load, and can be used in a wide range of operations from low loads to high loads. Is possible. On the other hand, the conventional vertical biomass mill can be operated only at a low load. From this data, it can be said that the vertical biomass mill 1 according to the embodiment is capable of high-load operation and has a high production capacity of biomass particles.

  The vertical biomass mill 1 of the present invention is characterized in that an internal wall 12 that restricts the return of the coarse particles C to the turntable 3 is installed in the housing 11, and other parts are described above. The present invention is not limited to the embodiment and can be changed as appropriate. For example, the vertical biomass mill 1 of the present invention can be configured by modifying a conventionally known coal mill, but is not limited thereto. In the embodiment, only the woody biomass is pulverized, but the coal and the woody biomass can be mixed and pulverized. According to the vertical biomass mill 1 of the present invention, when coal and wood biomass are mixed and pulverized, wood biomass can be mixed at a high ratio.

  Note that the vertical biomass mill 1 of the present invention is configured so that the inner wall 12 can be attached to and detached from the housing 11, so that the inner wall 12 is removed from the housing 11, and the rotational classifier 6 is disposed at the lower part of the rotational classifier 6. By providing a hopper that returns the coarse particles C that have not passed through the machine 6 or the fixed classifier 7 to the center of the rotary table 3, it can be used as a coal mill.

  DESCRIPTION OF SYMBOLS 1 ... Vertical type biomass mill, 2 ... Table drive device, 3 ... Rotary table, 3a ... Groove, 4 ... Grinding roller, 5 ... Center chute, 6 ... Rotary classifier, 6a ... Fin, 6b ... Fin support annular plate , 7 ... Fixed classifier, 8 ... Bounce plate, 9 ... Distributing part, 9a ... Transport pipe, 11 ... Housing, 12 ... Inner wall, 13 ... Annular flow path, 14 ... Rotating throat vane, 15 ... Blowing of primary air Mouth, 16 ... primary air duct, 21 ... roller bracket, 22 ... roller pivot, 23 ... pressure frame, 24 ... pressure arm, 25 ... pressure cylinder, 26 ... pressure rod, 31 ... ring member, 32 ... Upper conical portion, 33 ... cylindrical portion, 34 ... desorption plate, 35 ... pressure arm through hole, 36 ... maintenance door, 37 ... access door, A ... woody biomass, B ... powder flow, C ... coarse particles

Claims (8)

A rotary table disposed in a lower part of the housing, a grinding roller for grinding woody biomass between the rotary table, a primary air outlet provided between the rotary table and the housing, A center chute for supplying woody biomass as a raw material to the center of the upper surface of the rotary table, a rotary classifier arranged at the top of the housing, a cylindrical inner wall arranged inside the housing, and the housing An annular flow path that is configured by an inner surface of the inner wall and an outer surface of the inner wall and guides the powder flow blown up by the primary air injected from the outlet to the rotary classifier,
The biomass mill, wherein the inner wall is configured to return coarse particles of the woody biomass that has not passed through the rotary classifier only to the annular flow path.   The inner wall includes a ring member disposed opposite to the rotary classifier, an upper cone portion whose diameter increases from an upper end portion to which the ring member is attached, and a lower end portion of the upper cone portion. 2. The biomass mill according to claim 1, wherein the biomass mill is configured by a coupled cylindrical portion and a plurality of detachable plates removably coupled to a lower end portion of the cylindrical portion.   The biomass mill according to claim 2, wherein the cylindrical portion includes a maintenance door capable of carrying in and out the crushing roller.   The biomass mill according to claim 2, wherein the detachable plate includes an access door through which a person can go in and out.   The inner wall is detachably attached to the housing through a required clearance between the upper surface of the ring member and the lower end of the rotary classifier, which can prevent biting of woody biomass. The biomass mill according to claim 2, wherein:   The biomass mill according to claim 2, wherein the desorption plate is disposed on an outer peripheral side of the crushing roller so as to overlap a part of the crushing roller.   The biomass mill according to claim 6, wherein the desorption plate is configured such that a lower end portion thereof covers a portion below a rotation center of the crushing roller.   The biomass mill according to claim 1, further comprising a contraction member that increases a flow rate of the powder flow flowing into the rotary classifier at an outer peripheral portion of the rotary classifier.

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