Vertical mill

Abstract

A vertical mill 100 comprises: a crushing table 120, a crushing roller 132, a distributor 114, an exhaust port 160, a blowout port 170, and an airflow formation part 180, all of which are provided within a cylindrical housing 110; an upstream-side contraction flow part 200 including an annular first upstream contraction flow ring 210, which is provided between the crushing roller 132 and the distributor 114 and which protrudes from the inner circumferential surface of the housing 110 toward the center of the housing 110, and an annular second upstream contraction flow ring 220, which is provided nearer to the center of the housing 110 than the first upstream contraction flow ring 210 and which protrudes toward the inner circumferential surface of the housing 110; and a downstream-side contraction flow part 300 including an annular first downstream contraction flow ring 310, which is provided between the upstream-side contraction flow part 200 and the distributor 114 and which protrudes from the inner circumferential surface of the housing 110 toward the center of the housing 110.

Description

Vertical Mill

[0001] This application claims the benefit of priority from Japanese Patent Application No. 2024-109788, filed on July 8, 2024, the contents of which are incorporated herein by reference.

[0002] For example, as shown in Patent Document 1, vertical mills for pulverizing materials such as coal, biomass, and cement raw materials are widely used. Vertical mills include a grinding table, grinding rollers, and an airflow generating unit. In vertical mills, the material to be pulverized is supplied between the grinding table and the grinding rollers. The material is then crushed by the grinding rollers on the grinding table and pulverized. Furthermore, in vertical mills, the airflow generating unit generates an ascending airflow from the grinding table toward the discharge port. Therefore, the pulverized material rides on the ascending airflow and moves from the grinding table to the discharge port, where it is discharged outside the vertical mill.

[0003] JP 2013-158667 A

[0004] In the above vertical mill, there is a demand for increasing the amount of material discharged per unit time.

[0005] In view of the above problems, the present disclosure aims to provide a vertical mill that can increase the amount of material discharged per unit time.

[0006] In order to solve the above problems, a vertical mill according to one aspect of the present disclosure includes a cylindrical housing, a grinding table provided within the housing, a grinding roller provided within the housing above the grinding table, a discharge port formed in the housing above the grinding roller, an air outlet provided at the outer edge of the grinding table or outside the outer edge, an airflow forming unit that forms an airflow from the air outlet toward the discharge port within the housing, a distribution unit that is provided between the grinding roller and the discharge port and has a flow path cross-sectional area that gradually increases from below toward above, and a pressure adjusting unit that is provided between the grinding roller and the distribution unit. the upstream contraction section is arranged between the upstream contraction section and the distribution section and narrows the flow path of the airflow, the upstream contraction section including a first annular upstream contraction ring protruding from the inner surface of the housing toward the center of the housing and a second annular upstream contraction ring located closer to the center of the housing than the first upstream contraction ring and opposite the first upstream contraction ring, and protruding toward the inner surface of the housing; and the downstream contraction section is arranged between the upstream contraction section and the distribution section and narrows the flow path of the airflow, the downstream contraction section including a first annular downstream contraction ring protruding from the inner surface of the housing toward the center of the housing.

[0007] The downstream contraction section may include a second annular downstream contraction ring provided on the first downstream contraction ring and protruding toward the center of the housing.

[0008] In order to solve the above-mentioned problems, another vertical mill according to one aspect of the present disclosure includes a cylindrical housing, a grinding table provided within the housing, a grinding roller provided within the housing above the grinding table, a discharge port formed in the housing above the grinding roller, an air outlet provided at the outer edge of the grinding table or outside the outer edge, an airflow forming unit that forms an airflow from the air outlet toward the discharge port within the housing, a distribution unit that is provided between the grinding roller and the discharge port and has a flow path cross-sectional area that gradually increases from below toward above, and a powder The housing has an upstream contraction section that is provided between the crushing roller and the distribution section and narrows the flow path of the airflow, the upstream contraction section including a second annular upstream contraction ring that is provided on the central side of the housing and protrudes toward the inner peripheral surface of the housing; and a downstream contraction section that is provided between the upstream contraction section and the distribution section and narrows the flow path of the airflow, the downstream contraction section including a first annular downstream contraction ring that protrudes from the inner peripheral surface of the housing toward the center of the housing, and a second annular downstream contraction ring that is provided on the first downstream contraction ring and protrudes toward the center of the housing.

[0009] The second downstream contraction ring may be configured to be detachable from the first downstream contraction ring.

[0010] The upstream contraction section and the downstream contraction section may be positioned such that the upstream contraction flow path formed by the upstream contraction section is closer to the inner surface of the housing than the downstream contraction flow path formed by the downstream contraction section.

[0011] The downstream contracted flow path formed by the downstream contracted portion may be inclined from the bottom to the top toward the center of the housing.

[0012] The downstream contraction section may include an annular third downstream contraction ring that is located closer to the center of the housing than the first downstream contraction ring, faces the first downstream contraction ring, and protrudes toward the inner circumferential surface of the housing.

[0013] According to the present disclosure, it is possible to increase the amount of material discharged per unit time.

[0014] 1 is a schematic diagram of a vertical mill according to an embodiment of the present disclosure, and FIG. 2 is an enlarged partial view of FIG.

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Dimensions, materials, and other specific numerical values ​​shown in the embodiments are merely examples for ease of understanding and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation. Elements not directly related to the present disclosure are not shown.

[0016] [1. Overview of the Vertical Mill] First, an overview of a vertical mill 100 according to an embodiment of the present disclosure will be described with reference to Fig. 1. Fig. 1 is a schematic diagram of the vertical mill 100 according to this embodiment. In Fig. 1, solid arrows indicate the flow of the material to be pulverized and the gas-solid two-phase flow. Also, dashed arrows in Fig. 1 indicate the flow of gas.

[0017] 1, the vertical mill 100 according to this embodiment includes, for example, a housing 110, a grinding table 120, one or more roller units 130, one or more pressure devices 140, a supply pipe 150, an outlet 160, an outlet 170, an airflow forming section 180, a rotary classifier 190, an upstream contraction section 200, and a downstream contraction section 300. For ease of understanding, only one roller unit 130 and one pressure device 140 are shown in FIG. 1, and the other roller units 130 and pressure devices 140 are omitted.

[0018] The housing 110 has a cylindrical shape. For example, the housing 110 has a substantially cylindrical shape. The housing 110 is provided such that the axial direction of the housing 110 is aligned vertically or substantially vertically.

[0019] The housing 110 includes a main body 112 and a distribution section 114. The inner diameter of the main body 112 is substantially constant along the vertical direction. The distribution section 114 is connected to the upper part of the main body 112. The inner diameter of the distribution section 114 gradually increases from the bottom to the top. In other words, the flow path cross-sectional area of ​​the distribution section 114 gradually increases from the bottom to the top. Note that a communication point 116 between the main body 112 and the distribution section 114 is, for example, smaller than the inner diameter of the main body 112.

[0020] The grinding table 120 is provided within the housing 110. The grinding table 120 is, for example, disk-shaped. The grinding table 120 is provided within the housing 110 so that its rotation axis is vertical. The grinding table 120 is rotated by a table drive motor 124 via a reducer 122. The grinding table 120 is rotated by the table drive motor 124 at a constant speed or a variable speed.

[0021] A groove 126 is formed on the upper surface of the rotary table 120. The groove 126 is an annular groove centered on the rotation axis of the rotary table 120. A vertical cross section of the groove 126 passing through the rotation axis of the rotary table 120 is arc-shaped.

[0022] One or more roller units 130 are provided. For example, three roller units 130 are provided. The roller unit 130 includes a crushing roller 132, a roller shaft 134, a bracket 136, and a pivot shaft 138. The crushing roller 132 is provided above the crushing table 120 within the housing 110. The crushing roller 132 is disposed, for example, at an incline above the groove 126 of the crushing table 120. The more material to be crushed that is guided into the groove 126, the smaller the inclination of the crushing roller 132 (approaching horizontal), and the fewer material to be crushed that is guided into the groove 126, the greater the inclination of the crushing roller 132.

[0023] In this embodiment, the three crushing rollers 132 are provided radially at 120° intervals from the rotation center of the crushing table 120. The crushing rollers 132 are supported by bearings (not shown) attached to roller shafts 134. The roller shafts 134 are inserted into a bracket 136. In addition to the roller shafts 134, a pivot shaft 138 is inserted into the bracket 136. The pivot shaft 138 is supported by a bearing (not shown).

[0024] One pressure device 140 is provided for each roller unit 130. In this embodiment, the vertical mill 100 has three roller units 130, and therefore three pressure devices 140 are provided. The pressure device 140 includes an actuator. The actuator is, for example, a hydraulic cylinder. The pressure device 140 presses the grinding roller 132 toward the grinding table 120. In this embodiment, the pressure device 140 presses a receiving seat 136a formed on the bracket 136. This causes a load to act on the receiving seat 136a. This causes the bracket 136 to swing around the pivot shaft 138 as the center of rotation. The grinding roller 132 swings together with the bracket 136 and is pressed downward toward the grinding table 120.

[0025] The supply pipe 150 is cylindrical. The supply pipe 150 is inserted through the upper wall 118 of the housing 110 so that its axial direction is vertical or approximately vertical. In this embodiment, the supply pipe 150 is inserted through the housing 110 so as to be coaxial with the housing 110. Also, in this embodiment, the supply pipe 150 is inserted through the housing 110 so as to be coaxial with the rotation axis of the grinding table 120. An upper opening of the supply pipe 150 is located outside the housing 110. A lower opening of the supply pipe 150 faces the grinding table 120 provided inside the housing 110. A material supplying device (not shown) is connected to the upper opening of the supply pipe 150. The material supplying device supplies the material to be ground onto the grinding table 120 through the supply pipe 150.

[0026] The material to be crushed is, for example, solid fuel such as coal or biomass pellets. The biomass is, for example, one or more of woody biomass, herbaceous biomass, and waste-based biomass. Woody biomass is, for example, wood, sawdust, bark, etc. Herbaceous (plant) biomass is, for example, sugarcane, sorghum, bamboo, wheat straw, rice straw, etc. Waste-based biomass is, for example, empty fruit bunches (EFBs) and palm kernel shells (PKSs) that are generated as a result of producing palm oil from palm trees.

[0027] The discharge port 160 is formed in the housing 110 above the grinding roller 132. The discharge port 160 is formed, for example, in the top wall 118 of the housing 110. Therefore, the distributor 114 is provided between the grinding roller 132 and the discharge port 160. In this embodiment, the vertical mill 100 is equipped with a plurality of discharge ports 160. The plurality of discharge ports 160 are formed in the top wall 118 of the housing 110 at approximately equal intervals along the circumferential direction of the housing 110. A discharge pipe 162 is connected to the discharge port 160. The discharge pipe 162 discharges the material ground by the grinding table 120 and the grinding roller 132 to the outside. The discharge pipe 162 is connected, for example, to a combustion port of a furnace that constitutes a power generation device.

[0028] The air outlets 170 are provided on the outer edge or outside the outer edge of the grinding table 120. In this embodiment, the vertical mill 100 is equipped with a plurality of air outlets 170. The plurality of air outlets 170 are provided outside the outer edge of the grinding table 120 and are formed at approximately equal intervals along the outer edge of the grinding table 120.

[0029] The airflow forming unit 180 forms an airflow from the air outlet 170 toward the exhaust port 160 within the housing 110. That is, the airflow forming unit 180 forms an ascending air current within the housing 110. The airflow forming unit 180 includes, for example, a blower that supplies gas to the air outlet 170. The gas supplied by the airflow forming unit 180 is, for example, air, combustion exhaust gas, or nitrogen. Note that the configuration of the airflow forming unit 180 is not limited as long as it can form an airflow from the air outlet 170 toward the exhaust port 160 within the housing 110. The airflow forming unit 180 may include, for example, a blower that sucks gas from the exhaust port 160 instead of or in addition to the blower that supplies gas to the air outlet 170 described above.

[0030] In this embodiment, the vertical mill 100 may also include a rotary classifier 190. The rotary classifier 190 is provided within the main body 112 of the housing 110. The rotary classifier 190 includes, for example, a rotary rotor 192 and a plurality of blades 194. The rotary rotor 192 is an annular member provided to surround the outer periphery of the supply pipe 150. The plurality of blades 194 are provided at approximately equal intervals around the circumferential direction of the rotary rotor 192. The rotary rotor 192 is rotated by a drive device (not shown). The rotation of the rotary rotor 192 rotates the plurality of blades 194. Note that, as will be described in detail later, in this embodiment, the rotation of the rotary rotor 192 may be stopped. Furthermore, the plurality of blades 194 may be removed.

[0031] 2. Operation of the Vertical Mill Next, the operation of the vertical mill 100 according to this embodiment will be described with reference to Fig. 1. First, the material to be crushed is supplied onto the crushing table 120 through the supply pipe 150 by the material to be crushed supply device.

[0032] The material to be crushed supplied to the crushing table 120 is caught between the recessed groove 126 of the crushing table 120 and the crushing roller 132. As the crushing table 120 rotates, the caught material to be crushed is crushed by the crushing roller 132 and crushed.

[0033] The pulverized material then rises within the main body 112 of the housing 110 together with the gas blown out through the outlet 170 by the airflow forming section 180. In other words, the pulverized material rises within the main body 112 of the housing 110 in a solid-gas two-phase flow state. The pulverized material then passes through the rotary classifier 190 and is transported by airflow to the distributor 114 of the housing 110.

[0034] As described above, the inner diameter of the distribution section 114 gradually increases from bottom to top. Therefore, the flow rate of the gas-solid two-phase flow transported to the distribution section 114 gradually decreases from bottom to top. This allows a vortex to be formed within the distribution section 114. The material to be pulverized is then efficiently dispersed within the distribution section 114 by the vortex. Therefore, the material to be pulverized is distributed approximately uniformly to the multiple discharge ports 160. The material to be pulverized distributed to the multiple discharge ports 160 is then discharged to the outside through the discharge pipe 162.

[0035] [3. Upstream contraction section and downstream contraction section] Next, the upstream contraction section 200 and downstream contraction section 300 according to this embodiment will be described in detail with reference to Figures 1 and 2. Figure 2 is a partial enlarged view of Figure 1. In Figure 2, solid arrows indicate the flow of the material to be pulverized and the gas-solid two-phase flow.

[0036] When coal is supplied to a furnace that constitutes a power generation system, the target particle size of the coal required in the furnace is, for example, about 40 μm. Therefore, in a vertical mill designed for pulverizing coal, the flow velocity of the ascending air current and the rotation speed of the rotary classifier are determined so that particles having a particle size of about 40 μm are discharged from the outlet.

[0037] On the other hand, when biomass is supplied to a furnace constituting a power generation apparatus, the target particle size of the biomass required in the furnace is, for example, 600 μm or more and 700 μm or less. That is, the target particle size of the biomass in the furnace is larger than the target particle size of coal, for example, 15 times or more the target particle size of coal. Therefore, when biomass is pulverized using a vertical mill designed for pulverizing coal, a problem occurs in that the biomass cannot be air-transported to the discharge outlet even though it has been pulverized to the target particle size. In other words, when biomass is pulverized using a vertical mill designed for pulverizing coal, the biomass cannot be air-transported to the discharge outlet unless it is excessively pulverized to the target particle size of coal.

[0038] Furthermore, biomass has lower pulverizability than coal. Therefore, when biomass is pulverized using a vertical mill designed for pulverizing coal, the amount of biomass remaining in the housing increases compared to when pulverizing coal. This results in a thick layer of biomass between the pulverizing table and the pulverizing rollers, further reducing the pulverizability of the biomass.

[0039] Therefore, the vertical mill 100 according to this embodiment is provided with an upstream contraction section 200 and a downstream contraction section 300 .

[0040] 3.1. Upstream Contraction Section The upstream contraction section 200 is provided between the grinding roller 132 and the distributor 114, and narrows the flow path of the airflow. In this embodiment, the upstream contraction section 200 is provided below the rotary classifier 190 in the main body 112 of the housing 110. The upstream contraction section 200 includes, for example, a first upstream contraction ring 210 and a second upstream contraction ring 220.

[0041] In the following description, terms such as "no flow path (gap) is formed," "without gaps," "no gaps formed," and "without gaps" mean that "no flow path (gap) is formed" or "there are no gaps" to the extent that a return flow path from above to below is not formed within the housing 110. Therefore, terms such as "no flow path (gap) is formed," "without gaps," "no gaps formed," and "without gaps" include cases where no flow path is formed at all, no gaps are formed at all, as well as cases where a flow path is formed to the extent that no return flow path is formed, and cases where gaps are formed to the extent that no return flow path is formed.

[0042] 2, the first upstream contraction ring 210 is annular and protrudes from the inner circumferential surface of the housing 110 toward the center of the housing 110. In order to restrict the flow path of the airflow to the upstream contraction flow path 250 formed by the first upstream contraction ring 210 and the second upstream contraction ring 220, the first upstream contraction ring 210 is attached to the inner circumferential surface of the housing 110 so that no flow path (gap) is formed.

[0043] In this embodiment, the vertical cross section of the first upstream contraction ring 210 passing through the axis of the housing 110 is, for example, trapezoidal. That is, the first upstream contraction ring 210 includes, for example, a flat surface 212 and inclined surfaces 214 and 216. The flat surface 212 extends in the vertical direction. The inclined surface 214 is provided below the flat surface 212. The inclined surface 214 slopes downward from the lower end of the flat surface 212 in a direction approaching the inner circumferential surface of the main body 112. The inclined surface 216 is provided above the flat surface 212. The inclined surface 216 slopes upward from the upper end of the flat surface 212 in a direction approaching the inner circumferential surface of the main body 112.

[0044] The first upstream contraction ring 210 may be configured by a plurality of arc-shaped divided members. For example, the first upstream contraction ring 210 may be formed by arranging a plurality of divided members closely together in the circumferential direction of the housing 110.

[0045] The second upstream contraction ring 220 is annular, and is provided closer to the center of the housing 110 than the first upstream contraction ring 210 , facing the first upstream contraction ring 210 , and protrudes toward the inner circumferential surface of the housing 110 .

[0046] In this embodiment, the vertical length from the upper end to the lower end of the second upstream contraction ring 220 is greater than the vertical length from the upper end to the lower end of the first upstream contraction ring 210. In this embodiment, the lower end of the second upstream contraction ring 220 is disposed below the lower end of the first upstream contraction ring 210. The upper end of the second upstream contraction ring 220 is disposed above the upper end of the first upstream contraction ring 210.

[0047] In this embodiment, the second upstream contraction ring 220 is provided on the outer peripheral surface of the supply pipe 150. The second upstream contraction ring 220 surrounds the outer peripheral surface of the supply pipe 150. The second upstream contraction ring 220 protrudes from the outer peripheral surface of the supply pipe 150 toward the inner peripheral surface of the main body 112 of the housing 110. In this embodiment, the amount by which the second upstream contraction ring 220 protrudes from the supply pipe 150 is greater than the amount by which the first upstream contraction ring 210 protrudes from the inner peripheral surface of the housing 110.

[0048] Similarly to the first upstream contraction ring 210, the second upstream contraction ring 220 is attached to the outer circumferential surface of the supply pipe 150 so as not to form any gaps (gaps) in order to restrict the airflow path to the upstream contraction flow path 250. The second upstream contraction ring 220 is, for example, hollow and formed of a plate member. The upper and lower ends of the second upstream contraction ring 220 are attached to the outer circumferential surface of the supply pipe 150 without any gaps. In this embodiment, the upper end of the second upstream contraction ring 220 is connected between the lower end of the supply pipe 150 and a position below the installation location of the rotary classifier 190 (described later) on the supply pipe 150. The lower end of the second upstream contraction ring 220 is connected to the lower end of the supply pipe 150.

[0049] The second upstream contraction ring 220 includes, for example, a flat surface 222, inclined surfaces 224 and 226, and a horizontal surface 228. The flat surface 222 extends in the vertical direction. The flat surface 222 faces the flat surface 212 of the first upstream contraction ring 210. The vertical length of the flat surface 222 is shorter than the vertical length of the flat surface 212 of the first upstream contraction ring 210. The inclined surface 224 is provided below the flat surface 222. The inclined surface 224 slopes downward from the lower end of the flat surface 222 toward the outer circumferential surface of the supply pipe 150. The lower end of the plate member constituting the inclined surface 224 is connected to the outer circumferential surface of the supply pipe 150 without any gaps. The inclined surface 226 is provided above the flat surface 222. The inclined surface 226 slopes upward from the upper end of the flat surface 222 toward the outer circumferential surface of the supply pipe 150. The horizontal surface 228 extends horizontally from the upper end of the inclined surface 226 toward the outer circumferential surface of the supply pipe 150. The tip of the plate member that constitutes the horizontal surface 228 is connected to the outer circumferential surface of the supply pipe 150 without any gaps.

[0050] The second upstream contraction ring 220 may be configured by a plurality of arc-shaped divided members, similar to the first upstream contraction ring 210. For example, the second upstream contraction ring 220 may be formed by arranging a plurality of divided members closely spaced apart along the circumferential direction of the supply pipe 150.

[0051] The inclined surface 214 of the first upstream contraction ring 210 and the inclined surface 224 of the second upstream contraction ring 220, as well as the flat surface 212 of the first upstream contraction ring 210 and the flat surface 222 of the second upstream contraction ring 220, form an upstream contraction flow channel 250. The upstream contraction flow channel 250 is an annular flow channel. The flow channel cross-sectional area of ​​the upstream contraction flow channel 250 is much smaller than the horizontal cross-sectional area of ​​the main body 112 of the housing 110.

[0052] As described above, the first upstream contraction ring 210 is attached to the inner peripheral surface of the housing 110 so as not to form any gaps, and the second upstream contraction ring 220 is attached to the outer peripheral surface of the supply pipe 150 so as not to form any gaps. As a result, no return flow path is formed for the material to be crushed that has passed through the upstream contraction flow path 250 to fall below the upstream contraction section 200.

[0053] 3.2. Downstream Contraction Section The downstream contraction section 300 is provided between the upstream contraction section 200 and the distribution section 114, and narrows the flow path of the airflow. In this embodiment, at least a portion of the downstream contraction section 300 is provided above the first upstream contraction ring 210 in the main body section 112 of the housing 110. The downstream contraction section 300 includes a first downstream contraction ring 310.

[0054] 2 , the first downstream contraction ring 310 is annular and protrudes from the inner circumferential surface of the housing 110 toward the center of the housing 110. In this embodiment, the amount of protrusion of the first downstream contraction ring 310 from the inner circumferential surface of the housing 110 is greater than the amount of protrusion of the first upstream contraction ring 210 from the inner circumferential surface of the housing 110.

[0055] The first downstream contraction ring 310 is mounted within the housing 110 without forming any gaps to restrict the airflow path in the downstream contraction flow path 350 formed by the first downstream contraction ring 310. The first downstream contraction ring 310 is, for example, hollow and formed of a plate member. The lower end of the first downstream contraction ring 310 is mounted without gaps to the inclined surface 216 of the first upstream contraction ring 210. The upper end of the first downstream contraction ring 310 is mounted without gaps to the inner surface of the upper wall of the main body 112 of the housing 110 via a plurality of contact plates 112a. The first downstream contraction ring 310 is, for example, welded to a plurality of contact plates 112a. The plurality of contact plates 112a are provided on the inner circumferential surface of the main body 112 of the housing 110. The plurality of contact plates 112a are provided at equal intervals around the circumferential direction of the main body 112 of the housing 110. The number of contact plates 112a corresponds to the number of divided members constituting a first downstream contraction ring 310, which will be described later, for example.

[0056] The first downstream contraction ring 310 includes, for example, inclined surfaces 312 and 314 and a flat surface 316. The inclined surface 312 faces the inclined surface 226 of the second upstream contraction ring 220. The inclined surface 312 slopes upward from the inclined surface 216 of the first upstream contraction ring 210 toward the center of the housing 110. The lower end of the plate member constituting the inclined surface 312 is connected to the inclined surface 216 of the first upstream contraction ring 210 without any gap. The inclined surface 314 is provided above the inclined surface 312. The inclined surface 314 slopes upward from the upper end of the inclined surface 312 toward the inner circumferential surface of the main body 112. The flat surface 316 is provided above the inclined surface 314. The flat surface 316 extends vertically from the upper end of the inclined surface 314 toward the upper wall of the main body 112. The tip of the plate member that forms the flat surface 316 is connected to the inner surface of the upper wall of the main body 112 without any gap.

[0057] The first downstream contraction ring 310 may be configured by a plurality of arc-shaped divided members, similar to the above-described first upstream contraction ring 210 and second upstream contraction ring 220. For example, the first downstream contraction ring 310 may be formed by arranging a plurality of divided members closely spaced apart along the inner circumferential direction of the main body 112.

[0058] In this embodiment, the downstream contraction section 300 may further include a second downstream contraction ring 320 and a third downstream contraction ring 330 .

[0059] The second downstream contraction ring 320 is provided on the first downstream contraction ring 310. The second downstream contraction ring 320 is annular and protrudes toward the center of the housing 110. The amount of protrusion of the second downstream contraction ring 320 from the first downstream contraction ring 310 is determined so as not to collide with, for example, the blades 194 of the rotary classifier 190.

[0060] Similarly to the first downstream contraction ring 310, the second downstream contraction ring 320 is attached to the first downstream contraction ring 310 without forming any gaps to restrict the airflow path in the downstream contraction flow path 350. The second downstream contraction ring 320 is, for example, hollow and made of a plate member. The lower end of the second downstream contraction ring 320 is attached to the inclined surface 314 of the first downstream contraction ring 310 without any gaps. The upper end of the second downstream contraction ring 320 is attached to the flat surface 316 of the first downstream contraction ring 310 without any gaps.

[0061] The second downstream contraction ring 320 includes, for example, inclined surfaces 322 and 324 and a horizontal surface 326. The inclined surface 322 slopes upward from the inclined surface 314 of the first downstream contraction ring 310 toward the center of the housing 110. The lower end of the plate member constituting the inclined surface 322 is attached to the inclined surface 314 of the first downstream contraction ring 310 without any gap. The inclined surface 324 is provided above the inclined surface 322. The inclined surface 324 slopes upward from the upper end of the inclined surface 322 toward the inner circumferential surface of the main body 112. The horizontal surface 326 is provided above the inclined surface 324. The horizontal surface 326 extends horizontally from the upper end of the inclined surface 324 toward the flat surface 316 of the first downstream contraction ring 310. The tip of the plate member that forms the horizontal surface 326 is connected to the flat surface 316 of the first downstream contraction ring 310 without any gap.

[0062] The second downstream contraction ring 320 may be configured by a plurality of arc-shaped divided members, similar to the first downstream contraction ring 310. For example, the second downstream contraction ring 320 may be formed by arranging a plurality of divided members closely spaced apart along the circumferential direction of the first downstream contraction ring 310.

[0063] Furthermore, the second downstream contraction ring 320 may be configured to be detachable from the first downstream contraction ring 310. The second downstream contraction ring 320 may be attached to the first downstream contraction ring 310 by, for example, bolts.

[0064] The third downstream contraction ring 330 is provided closer to the center of the housing 110 than the first downstream contraction ring 310, facing the first downstream contraction ring 310. The third downstream contraction ring 330 is annular and protrudes toward the inner circumferential surface of the housing 110. In this embodiment, the third downstream contraction ring 330 is attached to the rotary rotor 192 of the rotary classifier 190. The amount of protrusion of the third downstream contraction ring 330 from the rotary rotor 192 is determined so as not to collide with the blades 194, for example.

[0065] Similarly to the first downstream contraction ring 310 and the second downstream contraction ring 320, the third downstream contraction ring 330 is attached to the rotor 192 and the supply pipe 150 so as not to form any gaps in order to restrict the airflow path in the downstream contraction flow path 350. The third downstream contraction ring 330 is, for example, hollow and formed of a plate member. The lower end of the third downstream contraction ring 330 is attached without gaps to the lower part of the rotor 192 of the rotary classifier 190. The upper end of the third downstream contraction ring 330 is attached without gaps to the outer circumferential surface of the supply pipe 150. In the vertical mill 100 according to this embodiment, when the rotary classifier 190 is rotated, the upper end of the third downstream contraction ring 330 is slidably connected to the supply pipe 150. Meanwhile, in the vertical mill 100 according to this embodiment, when the rotation of the rotary classifier 190 is stopped, the upper end of the third downstream contraction ring 330 is directly connected to the supply pipe 150 .

[0066] The third downstream contraction ring 330 includes, for example, an inclined surface 332 and a horizontal surface 334. The inclined surface 332 faces the inclined surfaces 322, 324 of the second downstream contraction ring 320. The inclined surface 322 slopes upward from the bottom of the rotary rotor 192 of the rotary classifier 190 toward the center of the housing 110. The lower end of the plate member constituting the inclined surface 332 is connected to the rotary rotor 192 of the rotary classifier 190 without any gap. The horizontal surface 334 extends horizontally from the upper end of the inclined surface 332 toward the supply pipe 150. The tip of the plate member constituting the horizontal surface 334 is connected to the outer circumferential surface of the supply pipe 150 without any gap.

[0067] Note that a portion of the rotor 192 may penetrate the inclined surface 332 of the third downstream contraction ring 330 without any gap.

[0068] The third downstream contraction ring 330 may be configured by a plurality of arc-shaped divided members, similar to the first downstream contraction ring 310 and the second downstream contraction ring 320. For example, the third downstream contraction ring 330 may be formed by arranging a plurality of divided members closely spaced apart along the circumferential direction of the supply pipe 150.

[0069] A downstream contraction flow channel 350 is formed by the inclined surface 312 of the first downstream contraction ring 310 and the inclined surface 226 of the second upstream contraction ring 220, the inclined surface 314 of the first downstream contraction ring 310 and the inclined surface 332 of the third downstream contraction ring 330, and the inclined surfaces 322, 324 of the second downstream contraction ring 320 and the inclined surface 332 of the third downstream contraction ring 330. The downstream contraction flow channel 350 is an annular flow channel. The flow channel cross-sectional area of ​​the downstream contraction flow channel 350 is much smaller than the horizontal cross-sectional area of ​​the main body 112 of the housing 110. The flow channel cross-sectional area of ​​the downstream contraction section 300 may be equal to or different from that of the upstream contraction section 200. For example, the flow channel cross-sectional area of ​​a portion of the downstream contraction section 300 may be smaller than that of the upstream contraction section 200.

[0070] In addition, the upstream contraction section 200 and the downstream contraction section 300 may be positioned such that the upstream contraction flow path 250 formed by the upstream contraction section 200 is closer to the inner surface of the housing 110 than the downstream contraction flow path 350 formed by the downstream contraction section 300.

[0071] Furthermore, the downstream contracted flow path 350 formed by the downstream contracted section 300 may be inclined from the bottom to the top toward the center of the housing 110 .

[0072] As described above, the first downstream contraction ring 310 is attached to the inner peripheral surface of the housing 110 so as not to form any gaps, and the third downstream contraction ring 330 is attached to the outer peripheral surfaces of the rotary rotor 192 of the rotary classifier 190 and the supply pipe 150 so as not to form any gaps. As a result, no return flow path is formed for the material to be pulverized that has passed through the downstream contraction flow path 350 to fall below the downstream contraction section 300.

[0073] [4. Summary] As described above, the vertical mill 100 according to this embodiment includes the cylindrical housing 110, the grinding table 120 provided within the housing 110, the grinding roller 132 provided above the grinding table 120 within the housing 110, the discharge port 160 formed above the grinding roller 132 within the housing 110, the air outlet 170 provided at the outer edge of the grinding table 120 or outside the outer edge, the airflow forming unit 180 that forms an airflow from the air outlet 170 toward the discharge port 160 within the housing 110, the distribution unit 114 that is provided between the grinding roller 132 and the discharge port 160 and has a flow path cross-sectional area that gradually increases from below toward above, and the combination of the grinding roller 132 and the distribution unit 114. and a downstream contraction section 300 provided between the upstream contraction section 200 and the distribution section 114 to narrow the flow path of the airflow, the downstream contraction section 300 including an annular first upstream contraction ring 210 protruding from the inner circumferential surface of the housing 110 toward the center of the housing 110 and an annular second upstream contraction ring 220 provided closer to the center of the housing 110 than the first upstream contraction ring 210 and opposite the first upstream contraction ring 210, and protruding toward the inner circumferential surface of the housing 110; and a downstream contraction section 300 provided between the upstream contraction section 200 and the distribution section 114 to narrow the flow path of the airflow, the downstream contraction section 300 including an annular first downstream contraction ring 310 protruding from the inner circumferential surface of the housing 110 toward the center of the housing 110.

[0074] As a result, the vertical mill 100 according to this embodiment can increase the speed of the ascending air current in the space above the grinding roller 132 within the housing 110 compared to vertical mills designed for coal grinding. Therefore, when grinding biomass pellets, the vertical mill 100 according to this embodiment can effectively transport the biomass ground to a target particle size from the grinding table 120 to the discharge outlet using an air current. Therefore, the vertical mill 100 according to this embodiment can increase the amount of biomass discharged per unit time compared to grinding biomass pellets using a vertical mill designed for coal grinding. Furthermore, regardless of the type of material to be ground, the vertical mill 100 according to this embodiment can increase the amount of material to be ground per unit time compared to grinding the material using a vertical mill designed for coal grinding.

[0075] Furthermore, the vertical mill 100 according to this embodiment can increase the amount of biomass discharged per unit time, thereby reducing the amount of biomass remaining in the housing 110. As a result, the vertical mill 100 according to this embodiment can thin the layer of biomass between the grinding table 120 and the grinding roller 132, thereby improving the efficiency of grinding the biomass.

[0076] Furthermore, the vertical mill 100 according to this embodiment can increase the speed of the ascending air current simply by attaching the upstream contraction section 200 and the downstream contraction section 300 to a vertical mill designed for coal milling. Therefore, the vertical mill 100 according to this embodiment can achieve both an increase in the amount of biomass discharged per unit time and an improvement in the biomass milling efficiency with simple modifications.

[0077] Furthermore, the vertical mill 100 according to this embodiment includes a downstream contraction section 300 in addition to the upstream contraction section 200. If only the upstream contraction section 200 were provided, the material to be ground might stagnate above the upstream contraction section 200. This could prevent the material to be ground, transported by airflow from the grinding table 120, from entering the upstream contraction flow path 250. Therefore, the vertical mill 100 according to this embodiment includes a downstream contraction section 300 above the upstream contraction section 200. This allows the vertical mill 100 according to this embodiment to increase the flow velocity above the upstream contraction section 200. The flow velocity at which the material to be ground can be blown upward is determined by the particle size of the material to be ground. The downstream contraction section 300 according to this embodiment makes it possible to increase the flow velocity above the upstream contraction section 200 to a level at which the material to be ground can be blown upward after passing through the upstream contraction section 200. Therefore, the vertical mill 100 according to this embodiment can efficiently transport the material to be ground from above the upstream contraction section 200 to the discharge port 160. As a result, the vertical mill 100 according to this embodiment can avoid a situation in which the material to be ground becomes stagnant above the upstream contraction section 200, and can prevent obstruction to the transport of the material to be ground from the grinding table 120 to the upstream contraction section 200.

[0078] The downstream contraction section 300 may also include an annular second downstream contraction ring 320 that is provided on the first downstream contraction ring 310 and protrudes toward the center of the housing 110 .

[0079] As a result, the vertical mill 100 according to this embodiment can further increase the speed of the ascending air current, thereby further increasing the amount of material discharged per unit time.

[0080] Furthermore, the second downstream contraction ring 320 may be configured to be detachable from the first downstream contraction ring 310 .

[0081] This allows the vertical mill 100 according to this embodiment to adjust the speed of the ascending air current, making it possible to easily adjust the speed of the ascending air current to a speed suitable for the material to be ground.

[0082] In addition, the upstream contraction section 200 and the downstream contraction section 300 may be positioned such that the upstream contraction flow path 250 formed by the upstream contraction section 200 is closer to the inner surface of the housing 110 than the downstream contraction flow path 350 formed by the downstream contraction section 300.

[0083] As a result, the vertical mill 100 according to this embodiment can reduce the particle size of the material to be pulverized when it is airflow-transported to the discharge port 160. The upstream contracted flow channel 250 is preferably provided radially outward of the housing 110 relative to the outlet 170. This presumably allows larger particle sizes to collide with the wall near the inlet of the upstream contracted flow channel 250 and fall, while smaller particle sizes to be pulverized are presumably prevented from colliding with the wall near the inlet of the upstream contracted flow channel 250 and are smoothly transported to the upstream contracted flow channel 250. Therefore, by providing the upstream contracted flow channel 250 radially outward of the housing 110 relative to the outlet 170, the vertical mill 100 according to this embodiment can further reduce the particle size of the material to be pulverized when it is airflow-transported to the discharge port 160.

[0084] Furthermore, the downstream contracted flow path 350 formed by the downstream contracted section 300 may be inclined from the bottom to the top toward the center of the housing 110 .

[0085] As a result, the vertical mill 100 according to this embodiment can shorten the length of the downstream contracted flow channel 350, and can efficiently discharge the material to be pulverized.

[0086] In addition, the downstream contraction section 300 may include a third annular downstream contraction ring 330 that is located closer to the center of the housing 110 than the first downstream contraction ring 310, opposite the first downstream contraction ring 310, and protrudes toward the inner surface of the housing 110.

[0087] As a result, the vertical mill 100 according to this embodiment can further reduce the cross-sectional area of ​​the downstream contracted flow channel 350. Therefore, the vertical mill 100 according to this embodiment can further increase the speed of the ascending air current. Therefore, the vertical mill 100 according to this embodiment can further increase the discharge amount of the material to be ground per unit time.

[0088] As described above, the upper end of the first downstream contraction ring 310 is connected to the inner surface of the upper wall of the main body 112 of the housing 110 via a plurality of contact plates 112a. This makes it easy to position each divided member when the first downstream contraction ring 310 is made up of a plurality of divided members. Therefore, the divided members can be installed without gaps inside the housing 110, and the first downstream contraction ring 310 can be installed without gaps.

[0089] Although the embodiments have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to the above-described embodiments. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure.

[0090] For example, in the above embodiment, the downstream contraction section 300 includes the second downstream contraction ring 320. However, it is sufficient that the downstream contraction section 300 includes at least the first downstream contraction ring 310. Furthermore, in addition to the second downstream contraction ring 320, the downstream contraction section 300 may further include an annular fourth downstream contraction ring provided on the second downstream contraction ring 320 and protruding toward the center of the housing 110.

[0091] In the above embodiment, the second downstream contraction ring 320 is configured to be detachable from the first downstream contraction ring 310. However, the second downstream contraction ring 320 may be fixed to the first downstream contraction ring 310 by welding or the like.

[0092] In the above embodiment, the upstream contraction section 200 and the downstream contraction section 300 are positioned such that the upstream contraction flow path 250 is closer to the inner circumferential surface of the housing 110 than the downstream contraction flow path. However, the upstream contraction flow path 250 does not have to be located closer to the inner circumferential surface of the housing 110 than the downstream contraction flow path. The upstream contraction flow path 250 may be located closer to the center of the housing 110 than the downstream contraction flow path, for example.

[0093] In the above embodiment, the downstream contracted flow path 350 is inclined toward the center of the housing 110 from below to above. However, the downstream contracted flow path 350 does not have to be inclined toward the center of the housing 110 from below to above. The downstream contracted flow path 350 may extend vertically from below to above, for example. Furthermore, the downstream contracted flow path 350 may be inclined toward the inner circumferential surface of the housing 110 from below to above.

[0094] In the above embodiment, the downstream contraction section 300 includes the third downstream contraction ring. However, the downstream contraction section 300 may include at least the first downstream contraction ring 310.

[0095] In the above embodiment, the vertical mill 100 includes the rotary classifier 190. However, the vertical mill 100 does not necessarily need to include the rotary classifier 190. For example, when a vertical mill designed for coal pulverization is modified to the vertical mill 100 by adding the upstream contraction section 200 and the downstream contraction section 300, the rotary classifier 190 may be removed. In this case, the protrusion amount of one or more rings selected from the group consisting of the first downstream contraction ring 310, the second downstream contraction ring 320, and the third downstream contraction ring 330 of the downstream contraction section 300 can be increased, thereby reducing the cross-sectional area of ​​the downstream contraction channel 350. This increases the flow velocity of the ascending air current in the downstream contraction channel 350. This further increases the amount of material discharged per unit time.

[0096] Furthermore, when a vertical mill designed for coal pulverization is modified to become a vertical mill 100 by attaching the upstream contraction section 200 and the downstream contraction section 300, the blade 194 of the rotary classifier 190 may be removed. In this case, too, the protrusion amount of one or more rings selected from the group consisting of the first downstream contraction ring 310, the second downstream contraction ring 320, and the third downstream contraction ring 330 of the downstream contraction section 300 can be increased, thereby reducing the cross-sectional area of ​​the downstream contraction channel 350. This increases the flow velocity of the ascending air current in the downstream contraction channel 350. Therefore, it becomes possible to further increase the amount of material discharged per unit time.

[0097] In the above embodiment, the upstream contraction section 200 of the vertical mill 100 is provided with the first upstream contraction ring 210. However, the upstream contraction section 200 of the vertical mill 100 does not have to be provided with the first upstream contraction ring 210. In this case, the first upstream contraction ring 210 may be replaced with a second downstream contraction ring 320. That is, the housing 110 includes a cylindrical housing 110, a crushing table 120 provided within the housing 110, a crushing roller 132 provided above the crushing table 120 within the housing 110, a discharge port 160 formed above the crushing roller 132 within the housing 110, an air outlet 170 provided at the outer edge of the crushing table 120 or outside the outer edge, an air flow forming unit 180 that forms an air flow from the air outlet 170 toward the discharge port 160 within the housing 110, a distribution unit 114 that is provided between the crushing roller 132 and the discharge port 160 and has a flow path cross-sectional area that gradually increases from below toward above, and a flow path between the crushing roller 132 and the distribution unit 114. and a downstream contraction section (300) provided between the upstream contraction section (200) and the distribution section (114) to narrow the flow path of the airflow, the downstream contraction section (300) including a first annular downstream contraction ring (310) that protrudes from the inner circumferential surface of the housing (110) toward the center of the housing (110) and a second annular downstream contraction ring (320) that is provided on the first downstream contraction ring (310) and protrudes toward the center of the housing (110).

[0098] The present disclosure can contribute, for example, to Sustainable Development Goal (SDG) Goal 7 "Ensure access to affordable, reliable, sustainable and modern energy" and Goal 13 "Take urgent action to combat climate change and its impacts."

[0099] 100: Vertical mill 110: Housing 114: Distribution section 120: Grinding table 132: Grinding roller 160: Discharge port 170: Outlet 180: Air flow forming section 200: Upstream contraction section 210: First upstream contraction ring 220: Second upstream contraction ring 250: Upstream contraction flow channel 300: Downstream contraction section 310: First downstream contraction ring 320: Second downstream contraction ring 330: Third downstream contraction ring 350: Downstream contraction flow channel

Claims

an air outlet formed in the housing above the grinding roller; an air outlet provided at the outer edge of the grinding table or outside the outer edge; an airflow forming section that forms an airflow from the air outlet toward the air outlet within the housing; a distribution section that is provided between the grinding roller and the air outlet and has a flow path cross-sectional area that gradually increases from bottom to top; an upstream contraction section that is provided between the grinding roller and the distribution section and narrows the flow path of the airflow, the upstream contraction section including: a first annular upstream contraction ring that protrudes from the inner circumferential surface of the housing toward the center of the housing; and a second annular upstream contraction ring that is provided closer to the center of the housing than the first upstream contraction ring and opposite the first upstream contraction ring and protrudes toward the inner circumferential surface of the housing; and a downstream contraction section that is provided between the upstream contraction section and the distribution section and narrows the flow path of the airflow, a downstream contraction portion including a first annular downstream contraction ring protruding from the inner circumferential surface of the housing toward the center of the housing.

2. A vertical mill according to claim 1, wherein the downstream contraction section includes an annular second downstream contraction ring provided on the first downstream contraction ring and protruding toward the center of the housing.

3. A cylindrical housing; a grinding table provided within the housing; a grinding roller provided within the housing above the grinding table; a discharge port formed in the housing above the grinding roller; an air outlet provided at the outer edge of the grinding table or outside the outer edge; an airflow forming section that forms an airflow from the air outlet toward the discharge port within the housing; a distribution section that is provided between the grinding roller and the discharge port and has a flow path cross-sectional area that gradually increases from bottom to top; an upstream contraction section that is provided between the grinding roller and the distribution section and narrows the flow path of the airflow, the upstream contraction section being provided at the center of the housing and including a second annular upstream contraction ring that protrudes toward the inner circumferential surface of the housing; and a downstream contraction section that is provided between the upstream contraction section and the distribution section and narrows the flow path of the airflow, the first annular downstream contraction ring that protrudes from the inner circumferential surface of the housing toward the center of the housing. a downstream contraction section including a second annular downstream contraction ring provided on the first downstream contraction ring and protruding toward the center of the housing.

4. A vertical mill according to claim 2 or 3, wherein the second downstream contraction ring is configured to be detachable from the first downstream contraction ring.

5. A vertical mill as described in claim 1 or 3, wherein the upstream contraction section and the downstream contraction section are positioned such that the upstream contraction flow path formed by the upstream contraction section is closer to the inner peripheral surface of the housing than the downstream contraction flow path formed by the downstream contraction section.

6. A vertical mill according to claim 1 or 3, wherein the downstream contraction flow path formed by the downstream contraction section is inclined from the bottom to the top toward the center of the housing.

7. A vertical mill as described in claim 1 or 3, wherein the downstream contraction section includes an annular third downstream contraction ring that is located closer to the center of the housing than the first downstream contraction ring, facing the first downstream contraction ring, and protruding toward the inner surface of the housing.

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