JP6163728B2 - 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 coal is mixed with woody biomass, fuel can be mixed and ground with existing coal roller 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 pulverizing table, and are jetted upward by primary air ejected at a high speed from the ejection port, and are fed to the burner from the feeding pipe. The

  In the case of a conventional coal roller mill, the primary air ejection port is inclined in the circumferential direction around the grinding table so that the primary air is ejected from the circumference of the grinding table. The coal particles squirted into the ascending are swirling in the mill.

  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.

  Also, the woody biomass blown up to the primary air rises while swirling in the mill, so the flow path becomes longer, making it difficult for the woody biomass to be discharged out of the mill and staying in the mill. This causes an increase in the differential pressure in the interior and increases the blast power and the power of the table driving device. Due to the increase in power of the table driving device, the pulverizing capacity of woody biomass is limited to about 10% of the pulverizing capacity of coal.

  As described above, when wood biomass is supplied to the coal roller mill or a mill having an equivalent structure and pulverized, the wood biomass of the mill exhibits a behavior different from that of coal, and sufficient pulverization efficiency and pulverization capacity are obtained. There was a problem that could not be obtained.

  In Patent Document 1, a separator is arranged at the upper part of the casing, and the lower part of the separator is covered with an inverted truncated conical cone, and is formed by a space sectional shape formed by the inner surface of the casing and the outer periphery of the cone. However, an arrangement is disclosed in which the speed of the rising gas stream is gradually increased and no stagnation occurs.

JP 2003-268394 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 that forms a classification chamber, a classifier provided at an upper portion of the classification chamber, a pulverization table provided at a lower portion of the classification chamber and driven by a table driving device, and a pressure applied to the pulverization table A plurality of pressure roller units each having a pressure roller, a spout for ejecting primary air from the periphery of the grinding table, a chute for supplying woody biomass to the center of the grinding table, and the chute A biomass mill comprising a contracted flow cylinder that reduces the flow passage cross-sectional area of the primary air covering and a guide portion that is positioned above the reduced flow cylinder and that gradually decreases in diameter from the inner wall of the housing toward the downstream side. It is concerned.

  Further, according to the present invention, the contracted flow cylinder has a cylindrical portion whose upper end is opened, and an inverted conical curved surface extending from the lower end of the cylindrical portion toward the lower end of the chute and gradually decreasing in diameter downward. The present invention relates to a biomass mill that includes a collection part and in which a ring-shaped gap is formed between the collection part and the chute.

  According to the present invention, the contracted flow cylinder has a cylindrical portion whose upper end is closed, and an inverted conical curved surface that extends from the lower end of the cylindrical portion toward the lower end of the chute and gradually decreases in diameter downward. It is comprised from an inverted truncated cone part, and concerns on the biomass mill which the lower end of this inverted truncated cone part and the outer peripheral surface of the said chute | shoot contact | abut.

  Furthermore, the present invention relates to a biomass mill in which the guide portion has a truncated conical curved surface whose diameter is reduced upward.

  According to the present invention, the housing forming the classification chamber, the classifier provided in the upper part of the classification chamber, the pulverization table provided in the lower part of the classification chamber and driven by the table driving device, and the pulverization table A plurality of pressure roller units having pressure rollers to be pressed against each other, a spout for ejecting primary air from the periphery of the crushing table, a chute for supplying woody biomass to the center of the crushing table, Since it includes a reduced flow cylinder that covers the chute and reduces the cross-sectional area of the primary air flow path, and a guide portion that is located above the reduced flow cylinder and gradually decreases in diameter from the inner wall of the housing toward the downstream side. The primary air having a reduced flow velocity after passing through the contracted flow tube can be smoothly deflected by the guide portion, so that the primary air can be prevented from staying and causing a pressure loss, and the woody biomass can be discharged. But Result in advance, it exhibits an excellent effect of obtaining aims to increase the crushing capacity.

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 ejection ports 19 are provided on the entire circumference so that the primary air is jetted along the inner wall of the housing 3. The ejection port 19 is vertical or substantially vertical, or in the range of 0 ° to 5 ° in the central direction of the grinding table 5 and −5 ° to 0 ° in the rotational direction of the grinding table 5. You may form so that it may incline.

  A fuel supply / discharge portion 21 is provided on the upper side of the housing 3, and a pipe-like chute 22 is provided so as to penetrate the center portion of the fuel supply / discharge portion 21. The chute 22 extends into the housing 3 and has a lower end located above the center of the crushing table 5. The chute 22 is supplied with woody biomass, for example, wood pellets, and the supplied wood pellets fall to the center of the crushing table 5.

  The chute 22 is provided with a contraction cylinder 23 so as to cover the lower part from the middle part of the chute 22, and a lower partial chamber 17 a is formed at the lower part of the contraction cylinder 23, and the upper part of the contraction cylinder 23 The upper partial chamber 17b is formed. The contracted flow cylinder 23 has a hollow structure, a cylindrical cylindrical portion 24 having an open upper end, and extends from the lower end of the cylindrical portion 24 toward the lower end of the chute 22 and gradually decreases in diameter downward. It is comprised with the collection part 25 which has an inverted conical curved surface which decreases, and the lower end of this collection part 25 is open | released. The upper end of the cylindrical portion 24 is supported by the chute 22 by a support member 26, and the collecting portion 25 is supported by the chute 22 by a support member 27.

  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, for example, 10 m / sec.

  The collecting unit 25 has a lower end located in the vicinity of the lower end of the chute 22, and an inner diameter of the lower end of the collecting unit 25 is larger than an outer diameter of the chute 22. A ring-shaped discharge port 29 having a predetermined width is formed between the chute 22 and the chute 22.

  A rotating tube 31 is fitted on the chute 22, and the rotating tube 31 is rotatably supported by a rotating tube support portion 32 via a bearing 33. A pulley 34 is provided at the upper end of the rotary pipe 31, a belt 36 is wound between the pulley 34 and the pulley 35, and the pulley 35 is fitted to the output shaft of the speed reducer 37, A classifier motor 38 is connected to the speed reducer 37. Thus, the rotary tube 31 is rotated by the classifier motor 38 via the speed reducer 37, the pulley 35, the belt 36, and the pulley 34.

  A blade 39 is attached to the rotary pipe 31, and a classifier 41 is constituted by the rotary pipe 31, the pulley 34, the pulley 35, the belt 36, the speed reducer 37, the classifier motor 38, and the blade 39. ing.

  The blades 39 have a strip shape and are arranged on the inverted conical curved surface at a predetermined angular pitch in the circumferential direction. The blade 39 is inclined from the lower end toward the upper end so as to be separated from the rotary tube 31, and is attached to the rotary tube 31 via a blade support portion 42. The diameter of the circle enveloping the lower end of the blade 39 is smaller than the diameter of the cylindrical portion 24.

  In addition, a guide portion 43 is formed on the inner wall of the housing 3 facing the blade 39 to surround the classifier 41 over the entire circumference. The guide portion 43 has a truncated conical curved surface whose lower end faces the upper end of the cylindrical portion 24 and inclines so as to approach the blade 39 upward from the inner wall of the housing 3. The upper end of 43 is located in the vicinity of the upper end of the blade 39.

  By providing the guide portion 43, the upper partial class chamber 17b formed above the cylindrical portion 24 has a structure in which the diameter is gradually reduced upward.

  The fuel supply / discharge section 21 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. The wood pellets are fed from the chute 22. The wood pellets flow from the lower end of the chute 22 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 jetted vertically or substantially vertically from the ejection port 19 formed vertically or substantially vertically around the pulverization table 5. Raised. 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 spouted from the ejection port 19 and is classified as a powder flow along the inner wall of the housing 3. The chamber 17 is raised.

  The powder flow rising in the classification chamber 17 flows into the contracted flow channel 28 while being guided by the inclination of the collection unit 25. Since the cross-sectional area of the contracted flow channel 28 is small, the powder flow is contracted and increased in the process of passing through the contracted flow channel 28.

  The powder flow that has passed through the contracted flow channel 28 is deflected toward the center along the inclination of the guide portion 43 and guided toward the classifier 41. Further, since the cross-sectional area of the upper partial chamber 17b is larger than that of the contracted flow passage 28, the powder flow is decelerated in the upper partial chamber 17b, and the powder flow is reduced by the deceleration. The powder is classified by gravity. By performing the gravity classification, the coarse powder having a large particle size and the wood pellet spouted to the primary air without being pulverized are separated from the powder flow.

  Further, after the gravity classification, the powder flow reaches the classifier 41, and the classifier 41 classifies the powder. Fine powder having a predetermined particle size or less flows into the classifier 41 while being accelerated by the rotation of the blade 39, and is sent from the pulverized material feed pipe 44 through the pulverized material feed port 45. It is supplied to a boiler burner (not shown). Since the upper partial chamber 17b is reduced in diameter toward the downstream side by the guide portion 43, the decelerated powder flow is increased again, and the pulverized material feed pipe is increased in the accelerated state. 44.

  The coarse powder and unpulverized wood pellets are repelled by the blade 39, the coarse powder repelled by the blade 39, the uncrushed wood pellets, and the coarse powder separated from the powder stream by gravity classification, Unground wood pellets fall into the cylindrical portion 24.

  In addition, since the ejection port 19 is formed vertically or substantially vertically so that the powder flow rises along the inner wall of the housing 3, the powder flow is placed inside the contracted flow tube 23. The air is blown upward without blowing, and the pressure inside the contracted flow cylinder 23 becomes lower than the pressure around the classifier 41. 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 tube 23, and the coarse powder that has fallen into the cylindrical portion 24 and the unflowed powder. The pulverized wood pellets fall together with the downward flow, slide down the slope of the collection unit 25, and fall onto the pulverization table 5 through the discharge port 29. 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 swung up in the classification chamber 17 and swung, the ejection port 19 Since the flow path from the crushed material feed pipe 44 is shortened and the powder flow is accelerated in the process of passing through the contracted flow path 28, the powder crushed material feed pipe The time to reach 44 is also shortened.

  The coarse powder and the unpulverized wood pellets that have been classified by the gravity and the classifier 41 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. Spouted by primary air.

  As described above, in the first embodiment of the present invention, for example, 1/15 times or more of the cross-sectional area of the housing 3 is 1/10 between the cylindrical portion 24 of the contracted flow cylinder 23 and the housing 3. Since the cylindrical contracted flow path 28 having a cross-sectional area less than double is formed, the powder flow passing through the contracted flow path 28 can be 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. Therefore, the pulverization capacity can be increased.

  Further, the guide part 43 having a truncated conical curved surface is provided above the contracted flow cylinder 23, and the guide part 43 deflects the powder flow that has passed through the contracted flow path 28 toward the classifier 41. As a result, the powder flow can be smoothly introduced into the classifier 41 without flowing into the outer peripheral side of the ceiling portion of the housing 3 which becomes a dead space, and the powder is formed at the ceiling portion of the housing 3. It is possible to prevent the flow from staying and causing pressure loss.

  Further, since the collecting part 25 extending downward from the lower end of the cylindrical part 24 toward the lower end part of the chute 22 is provided, coarse powder that has fallen into the cylindrical part 24 after classification and uncrushed Wood pellets can be reliably dropped onto the center of the crushing table 5.

  Further, since the discharge port 29 is formed between the lower end of the collection part 25 and the chute 22, the diameter of the discharge port 29 is smaller than the diameter of the discharge port 19. It is possible to prevent the primary air ejected from the inlet 19 from flowing into the contracted flow tube 23 from the outlet 29 and preventing the upward flow and the downward flow of the primary air from interfering with each other.

  Further, by making the inclination of the ejection port 19 vertical or substantially vertical, the upward flow of the primary air ejected from the ejection port 19 is made vertical or substantially vertical, so that the powder flow in the housing 3 Therefore, the flow path of the powder flow from the ejection port 19 to the pulverized material feed pipe 44 can be shortened. Therefore, the time for the powder to stay 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 second embodiment, the contracted flow cylinder 23 in the first embodiment has a cylindrical portion 46 whose upper end is closed, and extends from the lower end of the cylindrical portion 46 toward the lower end of the chute 22 and downwards. It is comprised from the inverted truncated cone part 47 which has an inverted conical curved surface in which a diameter reduces gradually. The lower end of the inverted truncated cone part 47 is in contact with the outer peripheral surface of the chute 22 so that no gap is formed between the inverted truncated cone part 47 and the chute 22.

  In addition, it is preferable that the upper surface of the cylindrical portion 46 is inclined downward from the central direction to the outer peripheral direction. By making the upper surface of the cylindrical portion 46 an inclined surface that inclines downward from the center direction toward the outer peripheral direction, when the supply of primary air for spraying powder is stopped, such as when the vertical mill 1 is stopped, The powder falling on the contracted flow cylinder 23 can be slid down from the upper surface of the contracted flow cylinder 23, and accumulation of powder on the contracted flow cylinder 23 can be prevented.

  In the second embodiment, the upper end of the cylindrical portion 46 is closed, and no gap is formed between the inverted truncated cone portion 47 and the chute 22. No downflow of primary air occurs. Accordingly, since all the primary air ejected from the ejection port 19 can be used for conveying the powder, the powder can be more actively discharged out of the vertical mill 1 and the pulverization capacity can be increased. Increase can be achieved.

  In the first and second embodiments, the guide portion 43 is configured to be a conical curved surface. However, the guide portion 43 may be a curved surface that gradually decreases in diameter upward. Needless to say.

DESCRIPTION OF SYMBOLS 1 Vertical mill 3 Housing 5 Crushing table 7 Table drive device 11 Pressure roller unit 12 Pressure roller 17 Classification chamber 19 Ejection port 22 Chute 23 Shrinking cylinder 24 Cylindrical part 25 Collection part 28 Shrinking flow path 29 Discharge port 41 Classifier 43 Guide 46 Cylindrical 47 Inverted truncated cone

Claims (2)

A housing forming a classification chamber, a classifier provided in the upper part of the classification chamber, a pulverization table provided in the lower part of the classification chamber and driven by a table driving device, and a pressure applied to the pulverization table A plurality of pressure roller units having rollers, an ejection port for ejecting primary air from the periphery of the pulverizing table, a chute for supplying woody biomass to the center of the pulverizing table, and the primary air covering the chute And a guide located above the reduced flow tube, gradually reducing in diameter from the inner wall of the housing toward the downstream side, and having a lower end facing the upper end of the reduced flow tube The contracted flow cylinder has a cylindrical portion whose upper end is closed, and an inverted conical curved surface extending from the lower end of the cylindrical portion toward the lower end of the chute and gradually decreasing in diameter downward. Having an inverted cone Is composed of a part, the top surface of the cylindrical portion is inclined downward toward the outer circumferential direction from the center direction, biomass mill and the lower end of the inverted truncated cone portion and the outer peripheral surface of the chute and wherein the abutting . The biomass mill according to claim 1 , wherein the guide portion has a truncated conical curved surface whose diameter decreases toward the downstream side .

Images