JP6869323B2 - Evaluation method of crushing capacity of vertical mill - Google Patents

Description

The present invention relates to a method for evaluating the crushing capacity of a vertical mill for evaluating the crushing capacity of a vertical mill when biomass is used as the solid to be crushed in a vertical mill that crushes and pulverizes a solid material. It is a thing.

In boilers and gasifiers, solid fuels such as coal and biomass are used as fuel. When this coal or the like is used as a solid fuel, for example, the raw material is crushed by a vertical mill to produce fine pulverized fuel, and the obtained pulverized fuel is used.

In this vertical mill, a crushing table is rotatably arranged at the lower part of the housing, and a plurality of crushing rollers can be carried around on the upper surface of the crushing table, and a crushing load can be applied. It is composed of. Therefore, when the raw coal is supplied from the coal supply pipe onto the crushing table, it is dispersed over the entire surface by centrifugal force to form a coal layer, which is crushed by being pressed by each crushing roller against the coal layer, and is crushed by the supply air. The dried and classified pulverized coal is discharged to the outside.

By the way, it has been proposed to use biomass as an alternative raw material for coal. Biomass is biomass of wood, plants, crops, kitchen waste and the like. However, when crushing by inserting a biomass calibration between the crushing roller of the vertical mill and the crushing table, this biomass raw material has compressibility unlike coal, so the crushing pressure is not sufficiently transmitted and crushing is performed. There is a problem that it is difficult to do.

As a solution to such a problem, for example, there is one described in Patent Document 1 below.

Japanese Unexamined Patent Publication No. 2013-184115

By the way, when crushing coal with a vertical mill, it is necessary to set the capacity of the vertical mill according to the type of coal. That is, since the roller pressing force in the vertical mill differs depending on the hardness and water content of coal, it is necessary to obtain the coal crushing capacity (crushing amount per unit time) according to the properties of the coal used. Conventionally, when coal is used as a crushing raw material, the crushability index HGI (Hardgrove Grindability Index) of coal is calculated by the crushability test method (hardgrove method) specified in JIS m 08801 or the like, and this crushability index HGI. Is used to set the coal crushing capacity according to the coal properties in the vertical mill. However, as described above, since the properties of the biomass raw material are completely different from those of coal, it is difficult to set the crushing capacity in the vertical mill by the same method, and the crushing capacity in the biomass-dedicated crushing mill is evaluated. There is a need for a way to do it.

The present invention solves the above-mentioned problems, and an object of the present invention is to provide a method for evaluating the crushing capacity of a vertical mill in which the crushing capacity of the vertical mill when crushing a biomass raw material is set with high accuracy.

The method for evaluating the crushing capacity of the vertical mill of the present invention for achieving the above object is a step of pre-grinding a biomass raw material to form a biomass crushed product having a predetermined raw material particle size set in advance, and the biomass crushing. A step of finely pulverizing a product by a hard glove crushability test according to a biomass raw material, a step of determining the generation rate of fine powder smaller than the evaluated particle size in the pulverized biomass raw material, and a step of obtaining the fine powder obtained in advance. It is characterized by having a step of evaluating the biomass crushing capacity from the correlation between the rate and the crushing capacity of the biomass crushing mill.

The method for evaluating the crushing capacity of the vertical mill of the present invention includes a step of pre-grinding a biomass raw material to form a biomass crushed product having a predetermined raw material particle size set in advance, and a hardware method in which the biomass crushed product is made according to the biomass raw material. A step of pulverizing by a glove crushability test and a step of calculating the hard glove crushability index of the biomass raw material by obtaining the weight of the fine powder smaller than the evaluation particle size in the pulverized biomass raw material were obtained in advance. It is characterized by having a step of evaluating the biomass crushing capacity from the correlation between the hard globe crushability index of the biomass raw material and the crushing capacity of the biomass-dedicated crushing mill.

Therefore, the crushing capacity of the biomass raw material having properties different from those of coal can be obtained, and as a result, the crushing capacity of the vertical mill when crushing the biomass raw material can be set with high accuracy.

The method for evaluating the pulverization capacity of a vertical mill of the present invention is characterized in that the evaluation particle size of the biomass pulverized product is set to 0.21 mm to 0.84 mm in the hard glove pulverization test.

Therefore, the crushing capacity of the biomass raw material can be obtained with high accuracy by setting the evaluation particle size of the pulverized biomass product that matches the properties of the biomass raw material.

The method for evaluating the crushing capacity of a vertical mill of the present invention is characterized in that the raw material particle size of the biomass raw material is set to 1.0 mm to 6.73 mm.

Therefore, by setting the raw material particle size of the biomass raw material that matches the properties of the biomass raw material, the crushing capacity of the biomass raw material can be obtained with high accuracy.

The method for evaluating the pulverization capacity of a vertical mill of the present invention is characterized in that the amount of the biomass pulverized product charged into the container for the hard glove pulverization test is set to 20 g to 40 g.

Therefore, the crushing capacity of the biomass raw material can be obtained with high accuracy by setting the amount of the crushed biomass material charged into the container suitable for the properties of the biomass raw material.

The method for evaluating the crushing capacity of a vertical mill of the present invention is characterized in that a container in which the biomass pulverized product is charged is rotationally pulverized at a preset predetermined rotation speed for 5 to 10 minutes.

Therefore, by setting the rotation speed of the container suitable for the properties of the biomass raw material, the crushing capacity of the biomass raw material can be obtained with high accuracy.

According to the crushing capacity evaluation method of the vertical mill of the present invention, the crushing capacity of the vertical mill when crushing the biomass raw material can be set with high accuracy.

FIG. 1 is a table showing milling data in a hardgrove grindability test using coal and biomass. FIG. 2 is a graph showing the ratio of pulverized volume to the ratio of the amount of pulverized material smaller than the evaluated particle size. FIG. 3 is a flowchart showing a method for evaluating the crushing capacity of the vertical mill of the present embodiment. FIG. 4 is a schematic configuration diagram showing a vertical mill. FIG. 5 is a plan view showing an arrangement of crushing rollers in a vertical mill.

Hereinafter, preferred embodiments of the method for evaluating the crushing capacity of the vertical mill according to the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to this embodiment, and when there are a plurality of embodiments, the present invention also includes a combination of the respective embodiments.

FIG. 4 is a schematic configuration diagram showing the vertical mill of the first embodiment, and FIG. 5 is a plan view showing an arrangement of crushing rollers in the vertical mill of the first embodiment.

Vertical mills grind solids such as coal and biomass. Here, biomass is a renewable organic resource derived from living organisms, for example, thinned wood, waste wood, drifting wood, grass, waste, sludge, tires, and recycled fuel (pellets and chips) made from these. ) Etc., and is not limited to those presented here.

In the vertical mill 10, as shown in FIGS. 4 and 5, the housing 11 has a vertical cylindrical hollow shape, and the solid material supply pipe 13 is mounted on the ceiling portion 12. The solid material supply pipe 13 supplies the solid material into the housing 11, and the lower end portion extends downward. A gantry 14 is installed at the lower part of the housing 11, and a crushing table 15 is rotatably arranged on the gantry 14. The crushing table 15 can be driven and rotated by a driving device (not shown), and faces the lower end of the solid material supply pipe 13. Further, the crushing table 15 has an inclined shape in which the central portion of the upper surface is high and is lowered toward the outside, and the outer peripheral portion is curved upward.

A plurality of crushing rollers 16 are arranged above the crushing table 15 so as to face each other. Each of the crushing rollers 16 is arranged above the outer peripheral portion of the crushing table 15 at equal intervals in the circumferential direction, and is rotatably supported by the first support shaft 17. Each support arm 18 is vertically swingably supported by the housing 11 by a second support shaft 19 whose intermediate portion is along the horizontal direction. The first support shaft 17 of the crushing roller 16 is supported at the tip of each support arm 18. Therefore, each crushing roller 16 swings up and down with the second support shaft 19 as a fulcrum so that the crushing roller 16 can approach and separate from the upper surface of the crushing table 15. Further, each crushing roller 16 has an outer peripheral surface in contact with the upper surface of the crushing table 15, and receives rotational force from the crushing table 15 to rotate around.

Further, each support arm 18 is provided with a reaction force load applying member 20 for applying a reaction force load of each crushing roller 16 to the upper end portion 18a, while a stopper 21 is provided for the lower end portion 18b. Each support arm 18 receives a load from the reaction force load applying member 20, and presses each crushing roller 16 against the upper surface of the crushing table 15. Therefore, when the solid matter is supplied to the central portion of the crushing table 15, the solid matter moves to the outer peripheral side by centrifugal force and enters the gap between each crushing roller 16 and the crushing table 15. Each crushing roller 16 crushes by applying a solid matter pressing load by a load from the reaction force load applying member 20.

Further, the housing 11 is provided with an inlet port 22 located on the outer periphery of the crushing table 15 at the lower part and into which the primary air is sent, while the rotary separator 23 for classifying the crushed material and the outlet for discharging the classified crushed material are discharged at the upper part. A port 24 is provided. Further, the housing 11 is provided with a foreign matter discharge pipe 25 at the lower part.

When designing and manufacturing such a vertical mill 10, it is necessary to set the crushing capacity (driving force) of the vertical mill according to the properties of the raw material to be crushed. In this case, when the raw material to be crushed is coal, the grindability index HGI of coal is calculated by the grindability test method (hardgrove method) determined by Japanese Industrial Standards (JIS m 08801, etc.), and this grindability index HGI Is used to set the coal crushing capacity in the vertical mill 10.

FIG. 1 is a table showing milling data in a hardgrove grindability test using coal and biomass.

In the hardgrove grindability test of coal, as shown in the table of FIG. 1, a raw material particle size of 0.6 mm to 1.18 mm, a charging amount of 50 g, a crushing time of 4 minutes, and an evaluation particle size of 0.074 mm are set. First, a pulverized coal product having a raw material particle size of 0.6 mm to 1.18 mm is formed by preliminary pulverization, and then the pulverized coal product is further pulverized using a hardgrove grindability test device. This hard glove crushability test device includes a container having a crushing chamber formed with a plurality of hemispherical recesses, a plurality of steel balls fitted in the recesses, and a top ring placed on the plurality of steel balls. 50 g of crushed coal is placed in each recess of the container, a steel ball is placed on it, and a top ring is placed on it. Then, the container is finely pulverized by rotating at a rotation speed of 15 to 20 rotations per minute (15 rpm to 20 rpm) for 4 minutes.

Then, the pulverized coal product is sieved for 20 minutes to measure the weight W of the pulverized coal product having an evaluation particle size of 0.074 mm or less. Then, the Hardgrove Grindability Index HGI is calculated to the right of the decimal point using the following formula.
HGI = 13 + 6.93W

When the hardgrove grindability index HGI of coal is calculated in this way, for example, a correction integer is obtained based on a preset coal mill crushing capacity correction integer, and a correction integer is added to the reference coal crushing capacity of the vertical mill 10. Is multiplied to set the coal crushing capacity according to the coal properties. This coal crushing capacity is the driving force of the vertical mill 10 capable of crushing to an evaluated particle size of 0.074 mm per unit time.

On the other hand, since the biomass raw material has compressibility unlike coal, the hardgrove grindability index HGI of the biomass raw material is highly accurate in terms of the raw material particle size, the amount charged, the crushing time, and the evaluation particle size set according to the coal. Cannot be calculated, and it becomes difficult to set the optimum crushing capacity according to the biomass raw material.

Therefore, in the present embodiment, the test conditions in the hard glove pulverizability test that can set the optimum pulverization capacity according to the biomass raw material are set. That is, in the hard glove crushability test of the biomass raw material, as shown in the table of FIG. 1, the raw material particle size is 1.0 mm to 6.73 mm, the charging amount is 20 g to 40 g, and the crushing time is 5 to 10 minutes as the appropriate range 1. , The evaluation particle size is set to 0.21 mm to 0.84 mm.

In this case, for example, when wood pellets are applied as a biomass raw material, the wood pellets are obtained by compressing particles having a particle size of 0.6 mm to 1.0 mm and forming them into a cylindrical shape. It will be loosened. In the crushing of coal, lump coal having a particle size of 1 mm to 50 mm is crushed to a particle size of about 0.05 mm, while in the crushing of wood pellets, particles having a particle size of 0.6 mm to 1.0 mm are compression-molded. The molded body is pulverized to a particle size of about 0.5 mm to 1 mm. Therefore, if the grain size of the raw material is 0.6 mm to 1.18 mm, which is the same as that of coal, the grain size of the wood pellets after pre-grinding will be close to the grain size after fine crushing. The particle size was 1.0 mm to 6.37 mm, which can be finely pulverized by the test device. The particle size of the raw material is preferably 1.18 mm to 4.76 mm as the appropriate range 2. Moreover, the biomass raw material is not limited to wood pellets.

In addition, since biomass raw materials (wood pellets) are lighter than coal, if the same crushing container as coal is used, it is necessary to reduce the amount charged in order to secure the same volume, and coal is charged. The amount of biomass charged was 20 g to 40 g, which was smaller than the amount of 50 g. The amount charged is preferably 30 g as the appropriate range 2.

When the rotation speed of the container filled with the biomass raw material was the same as that of coal, the compressible biomass had a long crushing time of 5 to 10 minutes. The crushing time is preferably 7 minutes as the appropriate range 2.

The evaluation particle size was set to 0.21 mm to 0.84 mm, which is larger than the evaluation particle size of coal of 0.074 mm, depending on the particle size of the particles in the wood pellets of 0.6 mm to 1.0 mm.

FIG. 2 is a graph showing a crushing volume ratio to a ratio of the amount of pulverized material smaller than the evaluated particle size. In the graph of FIG. 2, the ratio of the amount of pulverized material smaller than the evaluated particle size on the horizontal axis is the biomass raw material to the amount of pulverized material smaller than the evaluated particle size of 0.074 mm of coal obtained by the hardgrove grindability test. It is a ratio of the amount of finely pulverized material smaller than the evaluation particle size of 0.84 mm (0.21 mm). The crushing capacity ratio on the vertical axis is the crushing capacity of actual wood pellets evaluated and calculated by a crushing test using a vertical mill tester, and is shown as a ratio to the capacity of standard coal.

It is a graph created by performing a hardgrove grindability test on biomass raw materials A, B, C, D, and E having properties different from coal to obtain a hardgrove grindability index HGI. Generally, biomass raw materials are rich in elasticity and are said to be more difficult to crush than brittle materials such as minerals (coal, etc.). As can be seen from the graph of FIG. 2, the biomass raw material A was relatively easy to pulverize due to the influence of the grade and the like. It is 0.0, and the same grinding capacity as coal can be achieved. On the other hand, the biomass raw materials B and C are more difficult to crush than coal, so that the crushing processing capacity becomes smaller. Further, the biomass raw materials D and E are easier to crush than the biomass raw material A, so that the crushing processing capacity is large.

Here, a method for evaluating the crushing capacity of the vertical mill of the present embodiment will be described. FIG. 3 is a flowchart showing a method for evaluating the crushing capacity of the vertical mill of the present embodiment.

In the method for evaluating the crushing capacity of the vertical mill of the present embodiment, as shown in FIG. 3, in step S11, the biomass raw material is pre-crushed to form a pulverized biomass product having a raw material particle size of 1.0 mm to 6.73 mm. And collect. In step S12, the biomass pulverized product is finely pulverized using a hard glove pulverization test apparatus. This hardgrove grindability test device is similar to that for crushing coal, and 20 g to 40 g of crushed biomass is placed in each recess of the container, a steel ball is placed on it, and a top is placed on it. The ring is placed. Then, the container is pulverized by rotation at a rotation speed of 15 to 20 rotations per minute (15 rpm to 20 rpm) for 5 to 10 minutes.

In step S13, the pulverized biomass is sieved for 20 minutes, so that the pulverized biomass having an evaluation particle size of 0.21 mm to 0.84 mm or less is sieved and the weight W of the pulverized biomass is measured. Then, in step S14, the Hardgrove Grindability Index HGI of the biomass raw material is calculated to the right of the decimal point using the following mathematical formula.
HGI = 13 + 6.93W

In step S15, the calculated Hardgrove Grindability Index HGI of the biomass raw material is used to create a graph (biomass mill crushing capacity correction integer) showing the crushing capacity ratio to the ratio of the amount of crushed material smaller than the evaluation particle size in FIG. Find the correction integer based on. Then, in step S16, the reference biomass crushing capacity in the vertical mill 10 is multiplied by a correction integer to set the biomass crushing capacity according to the biomass properties. This biomass crushing capacity is the driving force of the vertical mill 10 capable of crushing the evaluated particle size from 0.21 mm to 0.84 mm per unit time.

As described above, in the method for evaluating the crushing capacity of the vertical mill of the present embodiment, the step of pre-grinding the biomass raw material to form a biomass crushed product having a predetermined raw material particle size set in advance and the biomass crushed product. Is finely pulverized by a hard glove crushability test according to the biomass raw material, a step of determining the generation rate of fine powder smaller than the evaluated particle size in the pulverized biomass raw material, and a predetermined generation rate of the fine powder. It has a step of evaluating the biomass crushing capacity from the correlation between the crushing capacity and the crushing capacity of the biomass crushing mill.

Further, in the method for evaluating the crushing capacity of the vertical mill of the present embodiment, a step of pre-grinding the biomass raw material to form a biomass crushed product having a predetermined raw material particle size set in advance and the biomass crushed product are used. A step of pulverizing by a hard glove crushability test according to a biomass raw material, and a step of calculating the hard glove crushability index of the biomass raw material by obtaining the weight of fine powder smaller than the evaluation particle size in the pulverized biomass raw material. The present invention includes a step of evaluating the biomass crushing capacity from the correlation between the hard glove crushability index of the biomass raw material and the crushing capacity of the biomass-dedicated crushing mill, which has been obtained in advance.

Therefore, the crushing capacity of the biomass raw material having properties different from those of coal can be obtained, and as a result, the crushing capacity of the vertical mill when crushing the biomass raw material can be set with high accuracy.

In the crushing capacity evaluation method of the vertical mill of the present embodiment, the evaluation particle size of the biomass pulverized product for calculating the hardgrove grindability index is set to 0.21 mm to 0.84 mm in the hardgrove grindability test. To do. Therefore, the crushing capacity of the biomass raw material can be obtained with high accuracy by setting the evaluation particle size of the pulverized biomass product that matches the properties of the biomass raw material.

In the method for evaluating the crushing capacity of the vertical mill of the present embodiment, the raw material particle size of the biomass raw material is set to 1.0 mm to 6.73 mm, and the amount of the crushed biomass to be charged into the container for the hard glove crushability test is 20 g. The amount is set to ~ 40 g, and the container in which the pulverized biomass is charged is pulverized at a preset predetermined rotation speed for 5 to 10 minutes. Therefore, the crushing capacity of the biomass raw material can be obtained with high accuracy by setting the raw material particle size of the biomass raw material suitable for the properties of the biomass raw material, the amount of the crushed biomass material charged into the container, and the rotation speed of the container.

10 Vertical mill 11 Housing 15 Crushing table 16 Crushing roller 18 Support arm

Claims (6)

A process of pre-grinding a biomass raw material to form a biomass pulverized product having a predetermined raw material particle size set in advance.
A step of finely pulverizing the pulverized biomass product by a hard glove pulverization test according to the biomass raw material, and
In the step of determining the generation rate of fine powder smaller than the evaluated particle size in the finely pulverized biomass raw material,
The process of evaluating the biomass crushing capacity from the correlation between the generation rate of the fine powder obtained in advance and the crushing capacity of the biomass crushing mill.
A method for evaluating the crushing capacity of a vertical mill, which comprises. A process of pre-grinding a biomass raw material to form a biomass pulverized product having a predetermined raw material particle size set in advance.
A step of pulverizing the biomass pulverized product by a hard glove pulverization test according to the biomass raw material
In the finely pulverized biomass raw material, a step of calculating the hardgrove grindability index of the biomass raw material by obtaining the weight of the fine powder smaller than the evaluated particle size, and
A step of evaluating the biomass crushing capacity from the correlation between the hardgrove grindability index of the biomass raw material obtained in advance and the crushing capacity of the biomass crushing mill.
A method for evaluating the crushing capacity of a vertical mill, which comprises. Evaluation of the pulverization capacity of the vertical mill according to claim 1 or 2, wherein the evaluation particle size of the biomass pulverized product is set to 0.21 mm to 0.84 mm in the hard glove pulverization test. Method. The method for evaluating the crushing capacity of a vertical mill according to any one of claims 1 to 3, wherein the raw material particle size of the biomass raw material is set to 1.0 mm to 6.73 mm. The pulverization of the vertical mill according to any one of claims 1 to 4, wherein the amount of the biomass pulverized product charged into the container of the hard glove pulverization test is set to 20 g to 40 g. Capacity evaluation method. The vertical mold according to any one of claims 1 to 5, wherein the container in which the biomass pulverized product is charged is rotationally pulverized at a predetermined rotation speed set in advance for 5 to 10 minutes. Mill crushing capacity evaluation method.

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