Method for adjusting biomass pellet crushing device, method for operating biomass pellet crushing device, biomass pellet crushing device, and boiler plant

Abstract

To provide a method for adjusting a biomass pellet crushing device capable of stably forming a fuel layer by installing a dam ring with the appropriate height, a method for operating the biomass pellet crushing device, as well as a biomass pellet crushing device and a boiler plant.SOLUTION: There is provided a method for adjusting a biomass pellet crushing device. The biomass pellet crushing device includes a housing 11, a rotating table 12, a drive unit, a dam ring, a fuel supply pipe 17, a crushing roller 13, and a water injection unit 82. When the table differential pressure, mill differential pressure, and mill power during the operation of the biomass pellet crushing device are mill load indexes, the height dimension of the dam ring is determined on the basis of at least one mill load index and the amount of water injected into the biomass pellets.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for adjusting a biomass pellet grinding apparatus, a method for operating a biomass pellet grinding apparatus, and a biomass pellet grinding apparatus and boiler installation. [Background technology]

[0002] Vertical roller mills (hereafter referred to as "mills") installed in thermal power plants and other facilities are used to pulverize, dry, and classify solid fuels such as coal and biomass pellets. The solid fuel is supplied onto a grinding table which rotates within a housing, and is supplied to a grinding section located on the outer periphery of the grinding table by the centrifugal force of the grinding table, where it is ground between a grinding roller which is supported for free rotation and the grinding section. The crushing roller is supported so that it can move toward and away from the crushing section, and when solid fuel gets caught between the crushing roller and the crushing table, a fuel layer is formed on the crushing table, and the crushing roller is lifted up onto the fuel layer, causing roller lift. Then, a crushing load is applied to the lifted crushing roller by a hydraulic cylinder or the like in a direction that presses it against the crushing table, thereby crushing the solid fuel. The pulverized solid fuel is dried by the carrier gas blown up from the blow-up section at the outermost periphery of the pulverizing table, blown up, and after the coarse fuel powder is separated by a classifier, it is transported to the downstream.

[0003] In recent years, the use of renewable energy has been promoted, and there is an increasing need to crush biomass in conventional coal mills. However, because biomass is fibrous, it is less easily pulverized by the crushing action of a mill than coal. To pulverize biomass using a coal mill, it is necessary to first perform preparatory processing by finely cutting the biomass fibers, and then supply the biomass pellets compressed into cylindrical shapes using a pelletizer or the like to the mill, or mix a small amount of finely cut biomass chips (approximately a few wt%) into the coal and pulverize it while the biomass fibers are cut by the grinding action of the coal.

[0004] When a large amount of biomass is to be crushed, biomass pellets (hereinafter referred to as "pellets") are generally used. Pellets tend to have a smaller roller lift than coal because a fuel layer is less likely to form on the grinding table. This is because the pellets supplied are cylindrically shaped, so they have a smoother surface with fewer irregularities than coal, and are of uniform diameter, so their movement is less likely to be restricted by the unevenness of the particles getting caught in each other like in coal, and because they have a cylindrical outer shape, they tend to roll like a roller, so the pellets move easily due to the inertial force (centrifugal force) caused by the rotation of the grinding table and the grinding load, and they tend to escape between the grinding roller and the grinding table.

[0005] In addition, depending on the raw material, pellets may contain large amounts of resin, wax, fat, tannin, etc., which cause a decrease in the coefficient of friction on the pellet surface and inhibit the formation of a fuel layer on the grinding table. Furthermore, to prevent fermentation and loss of shape during handling such as transportation and storage, the moisture content of the pellets is controlled to be approximately 10 wt% or less. When the surface of wood becomes too dry, the friction coefficient tends to drop rapidly. Therefore, in the winter when the air is too dry, the friction coefficient of the pellets drops and they become slippery.

[0006] When pellets with a reduced friction coefficient are supplied to the grinding table, the inertial force (centrifugal force) caused by the rotation of the grinding table causes them to slide or roll beyond the grinding section on the outer periphery of the grinding table and to the blow-up section on the outermost periphery of the grinding table, making it difficult for a fuel layer to form in the grinding section on the grinding table. In addition, the pellets remaining in the crushing section slide or roll when subjected to the crushing load from the crushing rollers, so they do not easily get caught between the crushing rollers and the crushing table, making it difficult to stably form a fuel layer. In particular, pellets made from raw materials that are hard and contain a lot of resin (for example, some broad-leaved trees such as acacia) have low coefficients of rolling friction and sliding friction and are prone to slipping. For such pellets, not only is it difficult to ensure roller lift, but they also cause a decline in the mill's grinding capacity because they are not caught between the grinding roller and the grinding table. In such cases, even though the mill has a large power margin, unground pellets remain inside the mill, causing the pressure difference between the upper and lower spaces on either side of the grinding table (table pressure difference) to rise, making it difficult to continue stable operation and creating a problem for which a solution was needed.

[0007] This is a crushing device that crushes minerals such as rocks rather than pellets, and Patent Document 1 describes that the thickness of the raw material layer on the crushing table can be adjusted by providing a dam ring on the outer periphery of the crushing table. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2003-71306 A Summary of the Invention [Problem to be solved by the invention]

[0009] In order to stably form a fuel layer, one possible method is to increase frictional resistance by injecting water onto the pellets before they are bitten between the grinding roller and the grinding table, thereby improving the biting ability between the grinding roller and the grinding table and thereby increasing grindability.

[0010] On the other hand, in order to ensure combustibility in the burner, the pulverized fuel (here meaning pulverized pellets) at the mill outlet must be dry, and this is controlled by keeping the temperature of the mixture of primary air (gas for transporting the pulverized fuel) and pulverized fuel at the mill outlet (hereinafter referred to as the "mill outlet temperature") above a specified temperature. In addition, since biomass generally has a higher volatile content and is more flammable than coal, the temperature of the primary air at the mill inlet (hereinafter referred to as the "mill inlet temperature") is kept below a specified temperature, taking into consideration the possibility of the pellets igniting. Due to this management method, when water is poured into the pellets, the ambient temperature inside the housing drops, which in turn drops the mill outlet temperature. In order to keep the mill outlet temperature at or above the specified temperature, the mill inlet temperature is increased, but if the mill inlet temperature exceeds the specified temperature, the mill cannot continue to operate. In addition, the water injected into the mill is discharged in gaseous form from the boiler as exhaust gas, and the latent heat of evaporation required in the process is lost in the exhaust gas, which can reduce boiler efficiency.

[0011] The present disclosure has been made in consideration of the above circumstances, and aims to provide a method for adjusting a biomass pellet crushing device, a method for operating a biomass pellet crushing device, and a biomass pellet crushing device and boiler equipment that can stably form a fuel layer by installing a dam ring of an appropriate height. [Means for solving the problem]

[0012] In order to solve the above problems, the biomass pellet crushing apparatus adjustment method, the biomass pellet crushing apparatus operation method, and the biomass pellet crushing apparatus and boiler equipment of the present disclosure employ the following means. A method for adjusting a biomass pellet grinding device according to one aspect of the present disclosure is a method for adjusting a biomass pellet grinding device, the biomass pellet grinding device including a housing, a rotary table provided inside the housing and rotating about a central axis, a drive unit for driving the rotary table, an annular member provided on an upper surface of the rotary table and centered on the central axis, a fuel supply pipe for supplying biomass pellets formed from a biomass raw material to an area of ​​the rotary table inside the annular member, a grinding roller that bites and grinds the biomass pellets between the rotary table and the grinding roller, and a grinding unit for grinding the biomass pellets on the rotary table. and a water injection section that injects water into the inlet of the housing, wherein the pressure difference between the space above and below the rotating table is defined as a table pressure difference, the pressure difference between the inlet of the housing into which a conveying gas for conveying the crushed biomass pellets flows in is defined as a mill pressure difference, and the power of the drive section is defined as a mill power. When the table pressure difference, the mill pressure difference, and the mill power during operation of the biomass pellet crushing device are defined as mill load indicators, the height dimension of the annular member is determined based on at least one of the mill load indicators and the amount of water injected into the biomass pellets.

[0013] Moreover, a method of operating a biomass pellet grinding device according to one aspect of the present disclosure is a method of operating a biomass pellet grinding device, the biomass pellet grinding device including a housing, a rotary table provided inside the housing and rotating about a central axis, a drive unit that drives the rotary table, an annular member provided on an upper surface of the rotary table and centered on the central axis, a fuel supply pipe that supplies biomass pellets formed from a biomass raw material to an area of ​​the rotary table inside the annular member, a grinding roller that bites and grinds the biomass pellets between the rotary table and the grinding roller, and a drive unit that drives the rotary table. and a water injection unit that injects water into the biomass pellets on the table, where the pressure difference between the space above and below the rotating table is defined as the table pressure difference, the pressure difference between the inlet of the housing into which a conveying gas for transporting the crushed biomass pellets flows in and the outlet of the housing from which the crushed biomass pellets and the conveying gas are discharged is defined as the mill pressure difference, and the power of the drive unit is defined as the mill power. When the table pressure difference, the mill pressure difference, and the mill power are defined as mill load indicators, a new amount of water injected is determined based on at least one of the mill load indicators and the amount of water injected into the biomass pellets.

[0014] In addition, a biomass pellet grinding device according to one embodiment of the present disclosure includes a housing, a rotating table provided inside the housing and rotating about a central axis, a ring-shaped member provided on an upper surface of the rotating table and centered on the central axis, a fuel supply pipe that supplies biomass pellets formed from biomass raw material to an area of ​​the rotating table inside the ring-shaped member, a grinding roller that grinds the biomass pellets by clamping them between the rotating table and the grinding roller, and a water injection section that injects water into the biomass pellets on the rotating table.

[0015] Moreover, a boiler facility according to one aspect of the present disclosure includes the above-described biomass pellet crushing device, and a boiler that generates steam by burning the crushed biomass crushed by the biomass pellet crushing device in a combustion device. Effect of the Invention

[0016] According to the present disclosure, a fuel layer can be stably formed by installing a dam ring of an appropriate height. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic configuration diagram of a power plant according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram showing the main part of the mill shown in FIG. [Diagram 3] FIG. 3 is a plan view of the grinding table and grinding rollers of the mill of FIG. 2. [Figure 4] FIG. 3 is a partial enlarged view of part D in FIG. [Diagram 5] FIG. 5 is a partially enlarged cross-sectional view of a portion E in FIG. 4. [Figure 6] FIG. 6 is a plan view of FIG. 5. [Figure 7A] 13 is a flowchart for adjusting the height of the dam ring. [Figure 7B] 7 is a flowchart for adjusting the height of the dam ring (continuation of FIG. 7A). [Figure 8A] 11 is a flowchart relating to adjustment of the amount of injected water. [Figure 8B] 8 is a flowchart for adjusting the amount of water injection (continuation of FIG. 8A). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a method for adjusting a biomass pellet crushing apparatus, a method for operating a biomass pellet crushing apparatus, and a biomass pellet crushing apparatus and boiler equipment according to one embodiment of the present disclosure will be described with reference to the drawings.

[0019] The power plant 1 includes a biomass pellet crusher 100 and a boiler 200 as boiler equipment, and a power generation section (not shown). In the following explanation, "upper" in terms such as upper part and top surface refers to the upper part vertically. Similarly, "lower" refers to the lower part vertically. However, the vertical direction is not precise and may include errors.

[0020] The biomass pellet crushing device 100 is a device that crushes pellets formed from biomass raw material, generates pulverized fuel, and supplies the pulverized fuel to a burner 220 (combustion device) of a boiler 200. In the power plant 1 shown in FIG. However, the power plant 1 may include the biomass pellet crushing devices 100 in a number corresponding to the number of burners 220 included in one boiler 200.

[0021] The biomass pellet crushing device 100 includes a mill 10 (crusher), a bunker 21, a fuel supplying device 20, a blower 30 (carrier gas supplying unit), a state detecting unit 40, and a control unit 50.

[0022] The biomass raw materials used for pellets are organic resources derived from renewable living organisms, such as thinnings, waste wood, driftwood, grasses, agricultural and livestock waste, sewage sludge, etc., but are not limited to those listed here. Biomass fuels are carbon neutral, meaning they do not emit carbon dioxide, a greenhouse gas, because the organisms that are the raw materials take in carbon dioxide during their growth process, and various uses for them are being considered.

[0023] Pellets are formed into a specific shape during the manufacturing process, so their size is consistent compared to coal. For example, before being crushed, coal is in the form of lumps measuring 2 to 50 mm, whereas pellets are homogeneous, being cylindrical with a diameter of about 6 to 8 mm and a length of about 40 mm.

[0024] As shown in Figures 1 and 2, the mill 10 comprises a housing 11 (main body), a grinding table 12 (rotating table), grinding rollers 13, a reducer 14, a mill motor 15 (drive section) connected to the reducer 14 and driving the grinding table 12 to rotate, a rotary classifier 16 (classification section), a fuel supply pipe 17, and a classifier motor 18 that drives the rotary classifier 16 to rotate.

[0025] The housing 11 is formed in a cylindrical shape extending in the vertical direction, and is an enclosure that accommodates the grinding table 12, the grinding rollers 13, the rotary classifier 16, and a part of the fuel supply pipe 17 (a part including the lower end). The shape of the housing 11 may be changed as appropriate depending on the shapes of the components to be housed therein. For example, if the outer shape of the rotary classifier 16 is large, the diameter of the housing 11 may be increased only around the outer shape of the rotary classifier 16.

[0026] A reducer 14 is disposed near the bottom surface portion 41 of the housing 11 . A mill motor 15 is connected to the reducer 14, and the grinding table 12 is configured to rotate about a rotation axis L1 by the driving force transmitted from the mill motor 15 via the reducer 14.

[0027] As shown in FIG. 3, the crushing table 12 is a circular member when viewed from above, and is disposed so that a central portion thereof faces the lower end of the fuel supply pipe 17. As shown in Figs. 1 and 2, the upper surface of the grinding table 12 forms a smoothly inclined surface that is high in the center, becomes lower as it approaches the outer periphery, and then becomes higher again. The shape of the upper surface of the grinding table 12 may be appropriately changed. For example, the upper surface of the grinding table 12 may be an inclined surface that is low in the center and becomes higher as it approaches the outer periphery from the center.

[0028] A fuel supply pipe 17 is attached to the center of the ceiling portion 42 of the housing 11. The fuel supply pipe 17 is equipment that supplies pellets guided from the bunker 21 via the fuel supply device 20 into the housing 11, and is arranged vertically at the center position of the housing 11, with the part including the lower end being located inside the housing 11. The fuel supply pipe 17 supplies pellets from above toward the center of the upper surface of the crushing table 12. The crushing table 12 pinches the supplied pellets in a biting portion 70 formed between the crushing roller 13 and the table, and crushes the pellets.

[0029] When pellets are fed from the fuel supply pipe 17 into the center of the crushing table 12, the centrifugal force generated by the rotation of the crushing table 12 guides the pellets to the outer periphery of the crushing table 12, where they are sandwiched between the crushing table 12 and the crushing roller 13 and crushed. The crushed pellets are blown upward by a carrier gas (hereinafter referred to as "primary air") guided from a carrier gas inlet 11a (inlet) of the housing 11 connected to a carrier gas supply line 110, and are guided to a rotary classifier 16.

[0030] An outlet (not shown) is provided on the outermost portion of the grinding table 12 or in the part of the housing 11 facing the outer peripheral surface of the grinding table 12, which allows the primary air flowing in from the carrier gas inlet 11a to flow out into the space above the grinding table 12. A swirling blade (not shown) is installed at the air outlet, and applies a swirling force to the primary air blown out from the air outlet. The primary air given a swirling force by the swirling blade becomes an airflow having a swirling velocity component, and conveys the pellets pulverized on the crushing table 12 (hereinafter referred to as "crushed biomass") to the rotary classifier 16 located at the upper part inside the housing 11. The swirl blades may be provided on the grinding table 12 and rotate together with the grinding table 12, or may be provided on the housing 11.

[0031] Among the pulverized biomass, any particle larger than a predetermined particle size is classified by the rotary classifier 16, or falls without reaching the rotary classifier 16 and is returned to the grinding table 12 and is pulverized again between the grinding table 12 and the grinding roller 13.

[0032] The crushing roller 13 is a rotating body that crushes the pellets supplied onto the crushing table 12 from the fuel supply pipe 17 . The crushing roller 13 is pressed against the upper surface of the crushing table 12 and cooperates with the crushing table 12 to crush the pellets. 1 and 2, only one crushing roller 13 is shown as a representative example, but multiple crushing rollers 13 are arranged at regular intervals in the circumferential direction so as to press against the upper surface of the crushing table 12. For example, as shown in FIG. 3, three crushing rollers 13 are arranged at equal intervals in the circumferential direction on the crushing table 12, spaced at angular intervals of 120 degrees. In this case, the portions where the three crushing rollers 13 come into contact with the upper surface of the crushing table 12 (pressing portions) are equidistant from the rotation center axis of the crushing table 12.

[0033] The crushing roller 13 is configured so as to be swingable and displaceable up and down by the journal head 45. Therefore, the crushing roller 13 can move closer to or away from the upper surface of the crushing table 12. In other words, the crushing roller 13 can swing and displace freely, increasing or decreasing the distance between it and the upper surface of the crushing table 12. When the crushing table 12 rotates with the outer circumferential surface of the crushing roller 13 in contact with the pellets on the upper surface of the crushing table 12, the crushing roller 13 receives a rotational force from the crushing table 12 and rotates with the pellets. When pellets are supplied from the fuel supply pipe 17, the pellets are pressed and crushed in the bite portion 70 formed between the crushing roller 13 and the crushing table 12. At this time, the force with which the crushing roller 13 presses the pellets is called the crushing load.

[0034] A support arm 47 of the journal head 45 is supported on the side surface of the housing 11 by a support shaft 48 whose middle portion is aligned horizontally so that the crushing roller 13 can be swung and displaced up and down around the support shaft 48. A pressing device 49 is provided at the upper end portion on the vertically upper side of the support arm 47 . The pressing device 49 is fixed to the housing 11 and applies a crushing load to the crushing roller 13 via the support arm 47 etc. so as to press the crushing roller 13 against the crushing table 12 . The crushing load is applied, for example, by a hydraulic cylinder (not shown) that operates by the pressure of hydraulic oil supplied from a hydraulic device (not shown) installed outside the mill 10. The crushing load may also be applied by the repulsive force of a spring (not shown). The method of supporting the crushing roller 13 and the method of applying the crushing load are not limited to those described above. For example, the support shaft of the crushing roller 13 may be directly pressed by a hydraulic cylinder (not shown).

[0035] The rotary classifier 16 is provided at the upper part inside the housing 11, and has a hollow inverted cone or cylindrical outer shape. The rotary classifier 16 is provided with a plurality of blades 16a extending in the vertical direction at its outer periphery. The blades 16a are provided around the central axis of the rotary classifier 16 at predetermined intervals (equally spaced apart). The rotary classifier 16 is a device that classifies pulverized biomass into particles larger than a predetermined particle size (hereinafter, pulverized biomass exceeding a predetermined particle size will be referred to as "coarse fuel") and particles smaller than a predetermined particle size (hereinafter, pulverized biomass smaller than a predetermined particle size will be referred to as "fine fuel"). The rotary classifier 16 is rotationally driven by a classifier motor 18 controlled by a control unit 50 , and rotates around a fuel supply pipe 17 around a cylindrical axis (not shown) extending in the up-down direction of the housing 11 . The classifying section may be, for example, a fixed classifier equipped with a fixed hollow inverted cone-shaped casing and a plurality of fixed swirling vanes on the outer periphery of the casing instead of the blades 16a. The classifying section may also use a rotary classifier and a stationary classifier in combination.

[0036] When the pulverized biomass reaches the rotary classifier 16, due to the relative balance between the centrifugal force generated by the rotation of the blades 16a and the centripetal force of the primary air flow, large diameter coarse fuel particles are knocked down by the blades 16a and returned to the grinding table 12 for re-pulverization, and fine fuel particles are directed to the outlet port 19 (outlet) in the ceiling 42 of the housing 11. The pulverized fuel classified by the rotary classifier 16 is discharged together with the primary air from the outlet port 19 into the pulverized fuel supply line 120 and supplied to the burner 220 of the boiler 200 .

[0037] The fuel supply device 20 is connected to the bunker 21 by a downspout portion 24, which is a pipe extending vertically from the lower end of the bunker 21. A valve for switching the discharge state of pellets from the bunker 21 may be provided midway in the downspout portion 24. The fuel supply device 20 includes a conveying unit 22 and a coal feeder motor 23 . The conveying section 22 is, for example, a belt conveyor, and conveys pellets discharged from the lower end of the downspout section 24 to the upper end of the fuel supply pipe 17 by the driving force of the coal feeder motor 23, and deposits them inside the fuel supply pipe 17. The amount of pellets supplied to the mill 10 is controlled by a signal from the control unit 50, for example by adjusting the moving speed of the belt conveyor of the transport unit 22.

[0038] The pellets stacked in the downspout section 24 are uniform in size and shape compared to coal, so the gap-filling effect (material seal) of particles of different sizes and shapes is small, and the gaps formed between the pellets are large. As a result, the primary air inside the mill 10 may pass through gaps formed in the layer within the downspout section 24 and flow back from inside the mill 10 through the downspout section 24 to the bunker 21, causing a decrease in the pressure inside the mill 10. If the pressure inside the mill 10 drops, various problems may occur in the stable operation of the biomass pellet grinding apparatus 100 and the boiler 200, such as a deterioration in the transportability of the pulverized biomass inside the mill 10, generation of dust inside the fuel supply device 20 and at the top of the bunker 21, ignition of pellets inside the fuel supply device 20, the bunker 21, or the downspout section 24 due to the high temperature of the primary air, and a decrease in the amount of pulverized fuel transported to the burner 220. For this reason, a rotary valve 60 (see Figure 2) may be provided in the fuel supply pipe 17 connecting the fuel supply device 20 to the inside of the mill 10 to suppress the occurrence of backflow of the primary air and pulverized biomass from the inside of the mill 10 through the fuel supply device 20 and downspout section 24 to the bunker 21.

[0039] The air blowing section 30 is a device that blows primary air into the housing 11 to dry the pulverized biomass and transport it to the rotary classifier 16 . The blower section 30 includes, for example, a primary air fan 31 (PAF: Primary Air Fan), a hot gas flow path 30a, a cold gas flow path 30b, a hot gas damper 30c, and a cold gas damper 30d in order to appropriately adjust the flow rate and temperature of the primary air blown into the inside of the housing 11.

[0040] The hot gas flow passage 30a supplies a part of the air sent out from the primary air fan 31 as hot gas that has been heated by passing through an air preheater 34 (heat exchanger). The hot gas flow passage 30a is provided with a hot gas damper 30c. The opening degree of the hot gas damper 30c is controlled by the control unit 50. The flow rate of the hot gas supplied from the hot gas flow passage 30a is determined by the opening degree of the hot gas damper 30c.

[0041] The cold gas flow passage 30b supplies a part of the air sent out from the primary air ventilator 31 as cold gas at room temperature. The cold gas flow passage 30b is provided with a cold gas damper 30d. The opening degree of the cold gas damper 30d is controlled by the control unit 50. The flow rate of the cold gas supplied from the cold gas flow passage 30b is determined by the opening degree of the cold gas damper 30d.

[0042] The flow rate of the primary air is the sum of the flow rate of the hot gas supplied from the hot gas flow path 30a and the flow rate of the cold gas supplied from the cold gas flow path 30b. The temperature of the primary air is determined by the mixture ratio of the hot gas supplied from the hot gas passage 30a and the cold gas supplied from the cold gas passage 30b. The flow rate of the primary air and the temperature of the primary air are controlled by the control unit 50 .

[0043] The data measured or detected by the state detection unit 40 of the mill 10 is transmitted to the control unit 50. The state detection unit 40 is, for example, a differential pressure measuring means. The differential pressure measuring means is configured to measure the mill differential pressure, which is the difference between the pressure at the portion (carrier gas inlet 11a) where the primary air flows into the inside of the housing 11 from the carrier gas supply line 110 and the pressure at the outlet port 19 where the primary air and the pulverized fuel are discharged from the inside of the housing 11 to the pulverized fuel supply line 120. The differential pressure measuring means is configured to measure a table differential pressure. The table differential pressure is the differential pressure between the top and bottom of the grinding table 12. A specific example of the table differential pressure is the differential pressure between the carrier gas inlet 11a below the grinding table 12 and the rotary classifier 16 above the grinding table 12.

[0044] An increase or decrease in the mill differential pressure or table differential pressure corresponds to an increase or decrease in the amount of pellets or pulverized biomass (coarse fuel powder) circulating between the vicinity of the rotary classifier 16 and the vicinity of the grinding table 12 inside the housing 11. In other words, each of the mill differential pressure and the table differential pressure is one of the mill load indicators that indicates the load state of the mill 10. That is, the operation of the equipment that affects the pellet crushing state, the operating state of the boiler 200, etc. can be controlled based on the mill differential pressure or the table differential pressure. For example, the amount and particle size range of the pulverized fuel discharged from the outlet port 19 can be adjusted by adjusting the rotation speed of the rotary classifier 16 based on the mill differential pressure or the table differential pressure. Therefore, while maintaining the particle size of the pulverized fuel within a range that does not affect the combustibility of the pellets in the burner 220, the pulverized fuel in an amount corresponding to the supply amount of the pellets to the mill 10 can be stably supplied to the burner 220 provided in the boiler 200.

[0045] The state detection unit 40 is, for example, a temperature measurement means. The temperature measuring means detects the mill inlet temperature near the carrier gas inlet 11a, and controls the blower 30 so that the temperature is below an upper limit temperature according to the properties of the pellets to prevent ignition. The temperature measuring means detects the mill outlet temperature near the outlet port 19 and controls the blower 30 to maintain a predetermined temperature sufficient for drying the pulverized biomass.

[0046] The control unit 50 is a device that controls each part of the biomass pellet crushing device 100. The control unit 50, for example, transmits a drive command to the mill motor 15 to adjust the rotation speed of the grinding table 12. The control unit 50 can also obtain the power of the mill motor 15 (hereinafter referred to as "mill power"). This mill power is also one of the mill load indicators that indicates the load state of the mill 10. The control unit 50, for example, transmits a drive command to the classifier motor 18 to control the rotation speed of the rotary classifier 16 and adjust the classification performance. The control unit 50 adjusts the amount of pellets supplied to the mill 10, for example, by transmitting a drive command to the coal feeder motor 23. The control unit 50, for example, transmits an opening degree instruction for the hot gas damper 30c and the cold gas damper 30d to the blower unit 30, thereby controlling the opening degrees of the hot gas damper 30c and the cold gas damper 30d and adjusting the flow rate and temperature of the primary air.

[0047] The control unit 50 is composed of, for example, a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program, and the CPU reads the program into the RAM or the like and executes information processing and arithmetic processing to realize various functions. The program may be installed in a ROM or other storage medium in advance, may be provided in a state stored in a computer-readable storage medium, or may be distributed via a wired or wireless communication means. The computer-readable storage medium may be a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. The HDD may be replaced with a solid state disk (SSD) or the like.

[0048] The boiler 200 includes a furnace 210 and a burner 220. The boiler 200 generates steam by burning pulverized fuel supplied from the biomass pellet crushing device 100.

[0049] The burner 220 is a device that burns pulverized fuel to form a flame using a mixture of pulverized fuel and primary air supplied from the pulverized fuel supply line 120, and secondary air supplied by heating air (outside air) discharged from the forced draft fan 32 (FDF: Forced Draft Fan) in an air preheater 34. The pulverized fuel is combusted inside the furnace 210, and the high-temperature combustion gas passes through heat exchangers such as an evaporator, a superheater, and a coal economizer (not shown) before being discharged to the outside of the boiler 200.

[0050] The combustion gas discharged from the boiler 200 undergoes predetermined treatment in an environmental device (such as a denitrification device, dust collector, and desulfurization device, not shown), and then undergoes heat exchange with primary air and secondary air in an air preheater 34. The combustion gas is then guided via an induced draft fan (IDF) 33 to a chimney (not shown) and released into the outside air. The air heated by the combustion gas in the air preheater 34 and discharged from the primary air fan 31 is supplied to the above-mentioned hot gas flow path 30a.

[0051] The water supplied to each heat exchanger of the boiler 200 is heated in an economizer (not shown) and then further heated by an evaporator (not shown) and a superheater (not shown) to become high-temperature, high-pressure superheated steam. The superheated steam is sent to a steam turbine (not shown), which is one of the devices that make up the power generation section, and drives the steam turbine to rotate. The steam turbine is connected to a generator (not shown), which is one of the devices that make up the power generation section, via a rotating shaft. When the steam turbine rotates, the generator is rotated and electricity is generated. This constitutes the power plant 1.

[0052] FIG. 2 shows a main part of the mill 10. The mill 10 is provided with a water injection section 82 and a dam ring 62 (annular member).

[0053] [About the water injection section] The water injection unit 82 is a device that supplies water (indicated as W in FIG. 2) to the pellets on the crushing table 12. The water injection section 82 includes a water supply pipe 84 , and a flow meter 85 and a flow rate adjustment valve 86 provided on the water supply pipe 84 .

[0054] The water supply pipe 84 guides water from a water supply source (not shown) toward the upper surface of the grinding table 12 . Specifically, the water supply pipe 84 supplies water to a predetermined water injection area Rw so that the water does not interfere with the pulverized fuel flow A1 and the primary air flow A2. The water injection area Rw is located in front of the grinding roller 13 in the rotation direction (also in front of the biting portion 70) as shown in Fig. 3. The water injection area Rw may be set in the section from the center of the upper surface of the grinding table 12 to the biting portion 70. As shown in FIG. 2, the flow meter 85 measures the flow rate of water passing through the water supply pipe 84, and transmits the measurement value to the control unit 50 (see FIG. 1). The flow rate adjustment valve 86 is located upstream of the flow meter 85 in the direction in which the water flows in the water supply pipe 84 , and the opening degree thereof is controlled by commands from the control unit 50 . The flow meter 85 may be an on-site indicator, and the flow control valve 86 may be a manual valve. In this case, an operator or the like reads the flow rate of water passing through the water supply pipe 84 from the indicated value of the flow meter 85, and adjusts the opening of the flow control valve 86 so that the flow rate becomes a predetermined flow rate. The indicated value of the flow meter 85 and the opening of the flow control valve 86 are input by the operator or the like to the control unit 50 (see FIG. 1).

[0055] As shown in Figures 2 and 4, pellets supplied from the fuel supply pipe 17 are guided onto the grinding table 12 rotating around the rotation axis L1, and then crushed at the nip 70 between the grinding roller 13 and the pellets, forming a fuel layer 72 on the upper surface of the grinding table 12.

[0056] As shown in FIG. 2, the fine fuel from the pulverized biomass rises with the primary air (arrow A2) as indicated by arrow A1, and then passes through the rotary classifier 16 and is guided to the boiler 200.

[0057] As shown in Figure 4, after water is poured into the pellets, they become softened and lose their shape, causing the rolling friction coefficient to increase. At the same time, the coefficient of sliding friction between the pellets and / or between the pellets and the crushing section (crushing table 12 and crushing roller 13) also increases, thereby preventing the centrifugal force of the crushing table 12 or the crushing load of the crushing roller 13 from causing the pellets to escape from the crushing section and not be gripped in the gripping section 70.

[0058] On the other hand, if the moisture content of the pellets is insufficient, the pellets will escape from the bite portion 70 due to the low rolling friction coefficient, and the fuel layer 72 at the bite portion 70 will become thin.

[0059] [About Damring] The dam ring 62 is a component for increasing the height of the outer periphery of the grinding table 12, thereby increasing the volume on the grinding table 12 in which pellets can be accumulated (hereinafter referred to as the "mill volume"). 2 and 3, the dam ring 62 is attached along the outer periphery (outer edge) of the grinding table 12 radially outward of the multiple grinding rollers 13. Therefore, the dam ring 62 has an annular shape centered on the rotation axis L1. The dam ring 62 is formed of one layer of ring parts 63 or is formed by stacking a plurality of ring parts 63 in the vertical direction. The height of the dam ring 62 can be adjusted by changing the number of layers of the ring component 63. In some cases, the dam ring 62 does not need to be attached.

[0060] As shown in FIG. 3, one layer of ring part 63 includes a plate material 64 having a circular arc shape, and a plurality of plate materials 64 are arranged in the circumferential direction to form an annular ring part 63.

[0061] As shown in FIG. 5, the dam ring 62 (ring component 63 / plate material 64 ) is attached to the outer periphery of the upper surface of the grinding table 12 by bolts 65 . Specifically, the shaft of a bolt 65 inserted from above the dam ring 62 screws into the grinding table 12 and the head of the bolt 65 abuts against the upper surface of the dam ring 62, thereby attaching the dam ring 62 to the grinding table 12.

[0062] As shown in FIGS. 5 and 6, a cover 66 may be provided around the head of the bolt 65 . The cover 66 is a cylindrical part that covers the periphery of the head of the bolt 65 to suppress wear of the bolt 65 caused by pellets and foreign matter.

[0063] [How to adjust the dam ring] The height of the dam ring 62 is adjusted and determined during adjustment operation. Adjustment operation is an operation mode carried out before normal operation and has no continuity with normal operation. Normal operation is a planned operation mode aimed at combustion and power generation by the boiler 200. In contrast, adjustment operation is a preliminary operation mode aimed at adjustment and verification of the mill 10 to realize normal operation. Incidentally, even during adjustment operation, fuel may be pulverized, and combustion or power generation may occur in the boiler 200, but combustion or power generation itself is not the purpose. The dam ring adjustment method will be described below with reference to the flow chart shown in FIGS. 7A and 7B.

[0064] First, the dam ring 62 having an appropriate height is placed on the grinding table 12 (step S1). Next, the operation of the mill 10 is started (step S2). Note that this operation is an adjustment operation. Next, monitoring of the operating status of the mill 10 begins (step S3).

[0065] Next, through a combination including some of steps S4 to S19, the height of the dam ring 62 is (1) increased, (2) decreased, or (3) not changed (adjustment completed). In this embodiment, there are two routes for increasing the height of the dam ring 62, five routes for decreasing the height of the dam ring 62, and three routes for not changing the height of the dam ring 62. In the following, steps S4 to S19 will be described first, and then each route will be described.

[0066] [[For each step]] Step S4 is a step for determining whether the table differential pressure is within an appropriate range (hereinafter referred to as the "predetermined differential pressure range.") That is, step S4 is a step for determining whether the amount of pellets or pulverized biomass (coarse fuel powder) circulating between the vicinity of the rotary classifier 16 and the vicinity of the pulverizing table 12 inside the housing 11 is within an appropriate range. The outcome of this judgment will be either appropriate, excessive or excessive. "Appropriate" means that the table differential pressure is within a predetermined range, i.e., the amount of pellets or pulverized biomass (coarse fuel) circulating is appropriate. "Excessive" means that the table differential pressure is greater than a predetermined range of differential pressure, i.e., the amount of pellets or pulverized biomass (coarse fuel powder) circulating is excessive, making it difficult for the pulverized biomass to be transported to the next process (outside the mill 10). The term "too small" refers to a state in which the table differential pressure is smaller than a predetermined differential pressure range, i.e., the amount of pellets or pulverized biomass (coarse fuel powder) circulating is too small. It should be noted that the determination may be made using the mill differential pressure instead of the table differential pressure.

[0067] Step S5 is a step for determining whether the mill power is within an appropriate range (hereinafter referred to as the "predetermined power range") or not. That is, step S5 is a step for determining whether the amount of pellets deposited in the biting portion 70 is within an appropriate range or not. The outcome of this judgment will be either appropriate, excessive or excessive. "Appropriate" means that the mill power is within a predetermined power range, that is, the amount of pellets deposited in the bite portion 70 is appropriate (the thickness of the fuel layer 72 is appropriate). "Excessive" means that the mill power is greater than the predetermined power range. In other words, the amount of pellets deposited in the bite section 70 is excessive (the thickness of the fuel layer 72 is excessively thick). If the amount of pellets deposited is large, a large power is required to rotate the grinding table 12 (more energy is consumed). "Insufficient" means that the mill power is smaller than the predetermined power range. In other words, the amount of pellets deposited at the biting portion 70 is insufficient (the thickness of the fuel layer 72 is excessively thin). When the amount of pellets deposited is small, the grinding table 12 approaches an idle operation state, and the power becomes small (energy is not consumed).

[0068] The table differential pressure in step S4 and the mill power in step S5 are basically negatively correlated. That is, under the same operating conditions for the amount of fuel held in the mill 10, if the ratio of fuel held in a floating (circulating) state inside the housing 11 is large and the ratio of fuel held on the grinding table 12 is small, the table differential pressure increases and the mill power decreases. Conversely, under the same operating conditions for the amount of fuel held in the mill 10, if the ratio of fuel held in a floating (circulating) state inside the housing 11 is small and the ratio of fuel held on the grinding table 12 is large, the table differential pressure decreases and the mill power increases. Therefore, both can be used as parameters for estimating the circulation amount of pellets or pulverized biomass (coarse fuel). However, it may not be possible to predict which parameter (table differential pressure or mill power) will go out of the specified range first depending on the change in the circulation amount. Therefore, step S4 and step S5 included in each route described later may be interchanged or may be performed simultaneously.

[0069] Step S6 is a step for determining whether the mill inlet temperature is lower than the upper limit temperature or equal to or higher than the upper limit temperature. When the mill inlet temperature is equal to or higher than the upper limit temperature, it is a criterion for determining whether or not the pellets present inside the housing 11 may ignite.

[0070] Step S7 is a step for determining whether the pellet supply amount (hereinafter referred to as "biomass supply amount") is equal to or greater than the target value or less than the target value. During adjustment operation (trial run), pellets are not suddenly fed in with a biomass supply amount that meets the target value, but the biomass supply amount may be gradually increased from a small amount. Therefore, before the target value of the biomass supply amount is reached, the amount of water injected may be increased and an operation to lower the table differential pressure may be performed. After the table differential pressure has stabilized, if it is determined in this step that the biomass supply amount is less than the target value, the process proceeds to step S10 (described below) and the biomass supply amount is brought closer to the target value.

[0071] Step S8 is a step for determining whether the remaining amount of pellets (hereinafter referred to as "biomass remaining amount") remaining on the grinding table 12 after the mill 10 (biomass pellet grinding device 100) is stopped is less than a predetermined remaining amount value or is greater than or equal to a predetermined remaining amount value. When the remaining amount of biomass is equal to or greater than a predetermined remaining amount, this is a criterion for determining whether or not the pellets remaining on the grinding table 12 after the mill 10 has stopped may ignite.

[0072] Step S9 is a step for completing the adjustment of the height of the dam ring 62. In other words, the height dimension of the dam ring 62 is determined in step S9.

[0073] Step S10 is a step of increasing the amount of biomass supplied.

[0074] Step S11 is a step for determining whether or not the amount of water injected by the water injection unit 82 can be increased. Whether or not to increase the amount of injected water is determined based on, for example, whether the amount of injected water has reached the maximum flow rate of water that can be supplied in the system of water injection unit 82, and whether the mill inlet temperature is below the upper limit temperature. Specifically, when the amount of injected water reaches the maximum flow rate of water that can be supplied in the system of the water injection unit 82, the amount of injected water cannot be increased any further. Furthermore, if the mill inlet temperature is equal to or higher than the upper limit temperature, the amount of water poured in cannot be increased. The reason is as follows. That is, if the amount of water poured in is increased, the heat of vaporization generated when the moisture evaporates inside the mill 10 will cause the atmospheric temperature inside the mill 10, and therefore the mill outlet temperature, to drop. In response, the control unit 50 attempts to maintain the mill outlet temperature at a constant temperature or higher by raising the temperature of the primary air led to the mill 10. However, if the mill inlet temperature has already reached or exceeded the upper limit temperature, the temperature of the primary air cannot be raised. Therefore, it is not possible to increase the amount of water poured in, which would be accompanied by a drop in the mill outlet temperature.

[0075] Step S12 is a step in which the water injection by the water injection unit 82 is increased.

[0076] Step S13 is a step for determining whether or not the height of the dam ring 62 can be increased. Whether or not the height can be increased is determined based on, for example, whether the dam ring 62 has reached the upper limit of the height without interfering with other structures inside the housing 11, and whether the remaining amount of biomass is less than a predetermined remaining amount value. Specifically, when the dam ring 62 reaches its maximum height without interfering with other structures (eg, the support arm 47 directly above the dam ring 62), the dam ring 62 cannot be made any higher. Furthermore, if the remaining amount of biomass is equal to or greater than a predetermined remaining amount, the dam ring 62 cannot be made any higher. The reason is as follows. Increasing the height of the dam ring 62 increases the mill volume, which increases the amount of pellets piled up. This inevitably increases the remaining amount of biomass, which increases the possibility that the pellets remaining on the grinding table 12 after the mill 10 is stopped will ignite.

[0077] Step S14 is a step for increasing the height of the dam ring 62.

[0078] Step S15 is a step in which it is determined that the current height of the dam ring 62 is inappropriate and that the height of the dam ring 62 cannot be adjusted any further. In this case, maintenance of the crushing section is required.

[0079] Step S16 is a step for determining whether or not water is being poured by the water pouring unit 82. In other words, step S16 is a step for determining whether or not the amount of poured water is zero.

[0080] Step S17 is a step for reducing the water injection by the water injection unit 82.

[0081] Step S18 is a step for determining whether or not the height of the dam ring 62 can be reduced. Whether or not the height can be reduced is determined based on, for example, whether or not the dam ring 62 is installed and whether or not the remaining amount of biomass is less than a predetermined remaining amount value.

[0082] [[Route 1 to increase the height of the dam ring]] If the pressure difference is appropriate in step S4 and the mill power is insufficient in step S5, it is determined that the amount of pellets accumulated in the bite section 70 is insufficient and the amount of circulating pellets and pulverized biomass (coarse fuel powder) is excessive. Therefore, the amount of accumulation is increased to pulverize an appropriate amount of pellets, thereby reducing the amount of circulating pulverized biomass. Methods for achieving this include increasing the amount of water injected by the water injection section 82 or increasing the height of the dam ring 62. In this route, after the process moves from step S5 to step S11, it is determined in step S11 that the amount of injected water cannot be increased, and the process moves to step S13. If it is determined in step S13 that the height of the dam ring 62 can be increased, the height of the dam ring 62 is increased in step S14, and the process returns to step S2. If it is determined in step S13 that the height of the dam ring 62 cannot be increased, the process proceeds to step S15.

[0083] [[Route 2 to increase the height of the dam ring]] If the differential pressure is excessive in step S4, it is determined that the amount of pellets or pulverized biomass (coarse fuel) circulating is excessive. Therefore, the amount of accumulation is increased to pulverize an appropriate amount of pellets, thereby reducing the amount of pulverized biomass circulating. Methods for achieving this include increasing the amount of water injected by the water injection section 82 or increasing the height of the dam ring 62. In this route, after the process moves from step S4 to step S11, it is determined in step S11 that the amount of injected water cannot be increased, and the process moves to step S13. From here on, the process is the same as Route 1, which involves increasing the height of the dam ring.

[0084] [[Route 1 to reduce the height of the dam ring]] If the pressure difference is appropriate in step S4 and the mill power is excessive in step S5, it is determined that the amount of pellets accumulated in the bite section 70 is excessive and the amount of circulating pellets and pulverized biomass (coarse fuel powder) is insufficient. Therefore, the amount of accumulation is reduced and an appropriate amount of pellets is pulverized, thereby increasing the amount of circulating pulverized biomass. One method for achieving this is to reduce the amount of water injected by the water injection unit 82. In this route, after the process moves from step S5 to step S16, it is determined in step S16 that the amount of injected water is zero (that is, the state in which the amount of injected water cannot be reduced any further), and the process moves to step S18. If it is determined in step S18 that the height of the dam ring 62 can be reduced, the height of the dam ring 62 is reduced in step S19, and the process returns to step S2. If it is determined in step S18 that the height of the dam ring 62 cannot be reduced, the process proceeds to step S15.

[0085] [[Route 2: Lowering the height of the dam ring]] If the pressure difference is too low in step S4, it is determined that the amount of pellets or pulverized biomass circulating is too low. Therefore, the amount of accumulated pellets is reduced to pulverize an appropriate amount of pellets, thereby increasing the amount of pulverized biomass circulating. One method for achieving this is to reduce the amount of water injected by the water injection unit 82. In this route, after the process moves from step S4 to step S16, it is determined in step S16 that the amount of injected water is zero (that is, the state in which the amount of injected water cannot be reduced any further), and the process moves to step S18. From here on, the process is the same as Route 1, which involves lowering the height of the dam ring.

[0086] [[Route 3: Lowering the height of the dam ring]] If the pressure difference is appropriate in step S4 and the mill power is insufficient in step S5, it is determined that the amount of pellets accumulated in the bite section 70 is insufficient and the amount of circulating pellets and pulverized biomass (coarse fuel powder) is excessive. Therefore, the amount of accumulation is increased to pulverize an appropriate amount of pellets, thereby reducing the amount of circulating pulverized biomass. One method for achieving this is to increase the amount of water injected by the water injection unit 82. In this route, after the process moves from step S5 to step S11, it is determined in step S11 that the amount of injected water can be increased, and the process moves to step S12. After the amount of injected water is increased in step S12, if the mill inlet temperature is below the upper limit temperature in step S6 and the biomass supply amount is equal to or greater than the target value in step S7, the process proceeds to step S8. However, if the remaining amount of biomass is equal to or greater than the predetermined remaining amount in step S8, there is a high possibility that the pellets remaining on the grinding table 12 will ignite after the mill 10 is stopped. Therefore, the process proceeds to step S18 in order to reduce the amount of accumulated pellets. From here on, the process is the same as Route 1, which involves lowering the height of the dam ring. If the mill inlet temperature is equal to or higher than the upper limit temperature in step S6, the process proceeds to step S3 via step S17. If the biomass supply amount is less than the target value in step S7, the process proceeds to step S3 via step S10.

[0087] [[Route 4: Lowering the height of the dam ring]] If the differential pressure is excessive in step S4, it is determined that the amount of pellets or pulverized biomass (coarse fuel) circulating is excessive. Therefore, the amount of accumulation is increased to pulverize an appropriate amount of pellets, thereby reducing the amount of pulverized biomass circulating. One method for achieving this is to increase the amount of water injected by the water injection unit 82. In this route, after the process moves from step S4 to step S11, it is determined in step S11 that the amount of injected water can be increased, and the process moves to step S12. After the amount of injected water is increased in step S12, if the mill inlet temperature is below the upper limit temperature in step S6 and the biomass supply amount is equal to or greater than the target value in step S7, the process proceeds to step S8. However, if the remaining amount of biomass is equal to or greater than the predetermined remaining amount in step S8, there is a high possibility that the pellets remaining on the grinding table 12 will ignite after the mill 10 is stopped. Therefore, the process proceeds to step S18 in order to reduce the amount of accumulated pellets. From here on, the process is the same as Route 1, which involves lowering the height of the dam ring. If the mill inlet temperature is equal to or higher than the upper limit temperature in step S6, the process proceeds to step S3 via step S17. If the biomass supply amount is less than the target value in step S7, the process proceeds to step S3 via step S10.

[0088] [[Route 5 to reduce the height of the dam ring]] If the differential pressure is appropriate in step S4 and the mill power is appropriate in step S5, the process proceeds to step S6. If the mill inlet temperature is lower than the upper limit temperature in step S6 and the biomass supply amount is equal to or greater than the target value in step S7, the process proceeds to step S8. However, if the remaining amount of biomass is equal to or greater than the predetermined remaining amount in step S8, there is a high possibility that the pellets remaining on the grinding table 12 will ignite after the mill 10 is stopped. Therefore, the process proceeds to step S18 in order to reduce the amount of accumulated pellets. From here on, the process is the same as Route 1, which involves lowering the height of the dam ring. If the mill inlet temperature is equal to or higher than the upper limit temperature in step S6, the process proceeds to step S3 via step S17. If the biomass supply amount is less than the target value in step S7, the process proceeds to step S3 via step S10.

[0089] [[Route 1 without changing the height of the dam ring]] If the pressure difference is appropriate in step S4 and the mill power is insufficient in step S5, it is determined that the amount of pellets accumulated in the bite section 70 is insufficient and the amount of circulating pellets and pulverized biomass (coarse fuel powder) is excessive. Therefore, the amount of accumulation is increased to pulverize an appropriate amount of pellets, thereby reducing the amount of circulating pulverized biomass. One method for achieving this is to increase the amount of water injected by the water injection unit 82. In this route, after the process moves from step S5 to step S11, it is determined in step S11 that the amount of injected water can be increased, and the process moves to step S12. After the amount of injected water is increased in step S12, if the mill inlet temperature is below the upper limit temperature in step S6 and the biomass supply amount is equal to or greater than the target value in step S7, the process proceeds to step S8. If the remaining amount of biomass is less than the predetermined remaining amount in step S8, the pellets remaining on the grinding table 12 after stopping the mill 10 are unlikely to ignite. Therefore, it is determined that operation in this state is possible, and the height of the dam ring 62 is determined in step S9. If the mill inlet temperature is equal to or higher than the upper limit temperature in step S6, the process proceeds to step S3 via step S17. If the biomass supply amount is less than the target value in step S7, the process proceeds to step S3 via step S10.

[0090] [[Route 2, which does not change the height of the dam ring]] If the differential pressure is excessive in step S4, it is determined that the amount of pellets or pulverized biomass (coarse fuel) circulating is excessive. Therefore, the amount of accumulation is increased to pulverize an appropriate amount of pellets, thereby reducing the amount of pulverized biomass circulating. One method for achieving this is to increase the amount of water injected by the water injection unit 82. In this route, after the process moves from step S4 to step S11, it is determined in step S11 that the amount of injected water can be increased, and the process moves to step S12. After the amount of injected water is increased in step S12, if the mill inlet temperature is below the upper limit temperature in step S6 and the biomass supply amount is equal to or greater than the target value in step S7, the process proceeds to step S8. The rest of the process is the same as Route 1, where the height of the dam ring is not changed. If the mill inlet temperature is equal to or higher than the upper limit temperature in step S6, the process proceeds to step S3 via step S17. If the biomass supply amount is less than the target value in step S7, the process proceeds to step S3 via step S10.

[0091] [[Route 3, which does not change the height of the dam ring]] If the differential pressure is appropriate in step S4 and the mill power is appropriate in step S5, the process proceeds to step S6. If the mill inlet temperature is lower than the upper limit temperature in step S6 and the biomass supply amount is equal to or greater than the target value in step S7, the process proceeds to step S8. From here on, the process is the same as Route 1, where the height of the dam ring is not changed. If the mill inlet temperature is equal to or higher than the upper limit temperature in step S6, the process proceeds to step S3 via step S17. If the biomass supply amount is less than the target value in step S7, the process proceeds to step S3 via step S10.

[0092] To summarize the above routes, it can be seen that the height dimension of the dam ring 62 is determined based on at least one of the mill load indicators and the amount of water injected. In other words, at least one of the mill load index and the water injection amount are used as parameters to determine the height dimension of the dam ring 62.

[0093] [How to operate the mill] After the height of the dam ring 62 has been determined by the adjustment run, the mill 10 transitions to normal operation. In addition, during normal operation, the height of the dam ring 62 is not changed. The method of operating the mill will be described below with reference to the flow charts shown in FIGS. 8A and 8B.

[0094] First, normal operation of the mill 10 is started (step S2). At this time, injection of an appropriate amount of water may be started. Next, monitoring of the status of the mill 10 begins (step S3).

[0095] Next, adjustment of the amount of injected water is completed through a combination including some of steps S4 to S22. There are three routes through which the adjustment of the amount of water injected can be completed. In the following, steps S4 to S22 will be described first, and then each route will be described.

[0096] [[For each step]] Of steps S4 to S22, steps other than steps S1, S8, S9, S13, S14, S15, S18, S19, and S20 to S22 are the same as the dam ring adjustment method, and therefore, description thereof will be omitted here. Among steps S4 to S22, steps S1, S8, S9, S13, S14, S15, S18 and S19 are not included in this method. Step S20 is a step where the adjustment of the amount of poured water is completed, i.e., the amount of poured water is determined. Step S21 is a step of decreasing the amount of biomass supply. Step S22 is a step for carrying out maintenance of the grinding section after the mill 10 has stopped.

[0097] [[Root 1]] If the pressure difference is appropriate in step S4 and the mill power is insufficient in step S5, it is determined that the amount of pellets accumulated in the bite section 70 is insufficient and the amount of circulating pellets and pulverized biomass (coarse fuel powder) is excessive. Therefore, the amount of accumulation is increased to pulverize an appropriate amount of pellets, thereby reducing the amount of circulating pulverized biomass. After the process moves from step S5 to step S11, if it is determined in step S11 that the amount of injected water can be increased, the process moves to step S12. After increasing the amount of water injected in step S12, if the mill inlet temperature is below the upper limit temperature in step S6 and the biomass supply amount is equal to or greater than the target value in step S7, it is determined that operation under these conditions is possible, and the amount of water injected is determined. If the mill inlet temperature is equal to or higher than the upper limit temperature in step S6, the process proceeds to step S3 via step S17. If the biomass supply amount is less than the target value in step S7, the process proceeds to step S3 via step S10.

[0098] [[Root 2]] If the differential pressure is excessive in step S4, it is determined that the amount of pellets or pulverized biomass (coarse fuel) circulating is excessive. Therefore, the amount of accumulation is increased to pulverize an appropriate amount of pellets, thereby reducing the amount of pulverized biomass circulating. After the process moves from step S5 to step S11, if it is determined in step S11 that the amount of injected water can be increased, the process moves to step S12. The rest is the same as Route 1. If it is determined in step S11 that the amount of injected water cannot be increased, the process moves to step S3 via step S21.

[0099] [[Root 3]] If the differential pressure is appropriate in step S4 and the mill power is appropriate in step S5, the process proceeds to step S6. The rest is the same as Route 1.

[0100] The height adjustment of the dam ring 62 is repeated in this manner to set the amount of water to be poured.

[0101] [[Other Routes]] If the differential pressure is too low in step S4, the process proceeds to step S16. If it is determined in step S16 that the amount of injected water is zero (i.e., the state in which the amount of injected water cannot be reduced any further), the process proceeds to step S22. On the other hand, if it is determined in step S16 that the amount of injected water is not zero (i.e., the state in which the amount of injected water can be reduced), the process proceeds to step S3 via step S17. If the pressure difference is appropriate in step S4 and the mill power is excessive in step S5, the process proceeds to step S16. If it is determined in step S16 that the amount of water poured is zero, the process proceeds to step S22. On the other hand, if it is determined in step S16 that the amount of water poured is not zero, the process proceeds to step S3 via step S17. If the mill inlet temperature is equal to or higher than the upper limit temperature in step S6, the process moves to step S3 via step S17. Moreover, if the amount of biomass supply is less than the target value in step S7, the process proceeds to step S3 via step S10.

[0102] To summarise each of the above routes, it can be seen that the new water injection amount is determined based on at least one of the mill load indicators and the current water injection amount. In other words, at least one of the mill load indicators and the water injection amount are used as parameters to determine the new water injection amount.

[0103] The method for adjusting the biomass pellet crushing apparatus, the method for operating the biomass pellet crushing apparatus, and the biomass pellet crushing apparatus and boiler facility according to the present embodiment have the following advantages. In the adjustment operation, the height of the dam ring 62 can be determined taking into consideration at least one of the table differential pressure, the amount of water injected, the mill power, the mill inlet temperature, the amount of biomass supplied, and the amount of remaining biomass. In addition, during normal operation after the height of the dam ring 62 has been determined, the amount of water injected can be determined taking into consideration at least one of the table differential pressure, the amount of water injected, the mill power, the mill inlet temperature, and the amount of biomass supplied. By combining the dam ring 62 and the water injection section 82, it is possible to operate with a larger biomass supply amount than when using only one of them.

[0104] The method for adjusting the biomass pellet crushing apparatus and the method for operating the biomass pellet crushing apparatus, as well as the biomass pellet crushing apparatus and boiler facility according to the present embodiment described above, can be understood as follows. A method for adjusting a biomass pellet grinding device according to a first aspect of the present disclosure is a method for adjusting a biomass pellet grinding device (100), the biomass pellet grinding device (100) including a housing (11), a turntable (12) provided inside the housing (11) and rotating about a central axis (L1), a drive unit (15) for driving the turntable (12), an annular member (62) provided on an upper surface of the turntable (12) and centered on the central axis (L1), a fuel supply pipe (17) for supplying biomass pellets formed from a biomass raw material to a region of the turntable (12) inside the annular member (62), a grinding roller (13) for grinding the biomass pellets by biting them between the turntable (12) and the turntable (12), and and a water injection section (82) that injects water into the biomass pellets on the rotating table (12), wherein the pressure difference between the space above and below the rotating table (12) is defined as a table pressure difference, the pressure difference between an inlet (11a) of the housing (11) through which a conveying gas for conveying the crushed biomass pellets flows in and an outlet (19) of the housing (11) through which the crushed biomass pellets and the conveying gas are discharged is defined as a mill pressure difference, and the power of the drive section (15) is defined as a mill power. When the table pressure difference, the mill pressure difference, and the mill power during operation of the biomass pellet crushing device (100) are defined as mill load indexes, the height dimension of the annular member (62) is determined based on at least one of the mill load indexes and the amount of water injected into the biomass pellets.

[0105] According to the adjustment method for the biomass pellet grinding apparatus (100) of this embodiment, the height dimension of the annular member (62) is determined based on the table differential pressure and the amount of water injected into the biomass pellets. Therefore, for example, when the table differential pressure is too low and the amount of water injected is zero, the height dimension of the annular member (62) can be reduced; when the table differential pressure is too high and the amount of water injected cannot be increased, the height dimension of the annular member (62) can be increased; and when the table differential pressure is too high and the amount of water injected can be increased, the height dimension of the annular member (62) can be maintained (adjustment completed) under specified conditions.

[0106] Furthermore, according to the adjustment method for the biomass pellet grinding apparatus (100) of this embodiment, the height dimension of the annular member (62) is determined based on the mill power. Therefore, for example, when the table differential pressure is appropriate, the mill power is too low, and it is not possible to increase the amount of water injected, the height dimension of the annular member (62) can be increased, or when the table differential pressure is appropriate, the mill power is too high, and the amount of water injected is zero, the height dimension of the annular member (62) can be decreased.

[0107] Furthermore, according to the adjustment method for the biomass pellet grinding apparatus (100) of this embodiment, the height dimension of the annular member (62) is determined based on the table differential pressure and the mill power. Therefore, for example, when the table differential pressure and the mill power are appropriate, the height dimension of the annular member (62) can be maintained under specified conditions.

[0108] In a method for adjusting a biomass pellet grinding device according to a second aspect of the present disclosure, in the first aspect, the biomass pellet grinding device (100) is connected to the housing (11) at an inlet (11a) and includes a carrier gas supply line (110) that supplies a carrier gas for transporting the crushed biomass pellets to the inside of the housing (11), and the height dimension of the annular member (62) is determined based on a mill inlet temperature, which is the temperature of the carrier gas near the inlet (11a) while the biomass pellet grinding device (100) is operating, a biomass supply amount, which is the amount of the biomass pellets supplied while the biomass pellet grinding device (100) is operating, and a biomass remaining amount, which is the amount of the biomass pellets remaining on the rotate table (12) after the biomass pellet grinding device (100) is stopped.

[0109] According to the present embodiment of the method for adjusting the biomass pellet grinding apparatus (100), the height dimension of the annular member (62) is determined based on the mill inlet temperature. Therefore, for example, when the amount of water injection can be increased, it is possible to determine whether the mill inlet temperature is below the upper limit temperature or not when the amount of water injection is increased. In addition, once it is confirmed that the mill inlet temperature is below the limit value, the height dimension of the annular member (62) can be lowered if the biomass supply amount has reached the target value and the remaining biomass amount is equal to or greater than the limit value, or the height dimension of the annular member (62) can be maintained if the biomass supply amount has reached the target value and the remaining biomass amount is less than the limit value.

[0110] A method for operating a biomass pellet crushing device according to a third aspect of the present disclosure is a method for operating a biomass pellet crushing device (100), the biomass pellet crushing device (100) including a housing (11), a turntable (12) provided inside the housing (11) and rotating about a central axis (L1), a drive unit (15) for driving the turntable (12), an annular member (62) provided on an upper surface of the turntable (12) and centered on the central axis (L1), a fuel supply pipe (17) for supplying biomass pellets formed from a biomass raw material to a region of the turntable (12) inside the annular member (62), and a drive unit (15) for driving the turntable (12), The apparatus is equipped with a grinding roller (13) and a water injection section (82) that injects water into the biomass pellets on the rotating table (12), and the pressure difference between the space above and below the rotating table (12) is defined as a table pressure difference, the pressure difference between an inlet (11a) of the housing (11) into which a conveying gas for transporting the crushed biomass pellets flows in and an outlet (19) of the housing (11) from which the crushed biomass pellets and the conveying gas are discharged is defined as a mill power, and the power of the drive section (15) is defined as a mill power. When the table pressure difference, the mill pressure difference, and the mill power are defined as mill load indicators, a new amount of water injection is determined based on at least one of the mill load indicators and the amount of water injected into the biomass pellets.

[0111] According to the operating method of the biomass pellet grinding apparatus (100) of this embodiment, a new amount of water injected is determined based on the table differential pressure and the amount of water injected into the biomass pellets. Therefore, for example, if the table differential pressure is too low and the amount of water injected is not zero, the amount of water injected can be reduced; if the table differential pressure is too high and the amount of water injected can be increased, the amount of water injected can be increased; and after increasing the amount of water injected, the amount of water injected can be maintained under specified conditions (adjustment completed).

[0112] Furthermore, according to the operating method of the biomass pellet grinding apparatus (100) of this embodiment, a new amount of water injected is determined based on the mill power. Therefore, for example, if the table differential pressure is appropriate, the mill power is excessive, and the amount of water injected is not zero, the amount of water injected can be reduced; if the table differential pressure is appropriate, the mill power is too low, and the amount of water injected can be increased, the amount of water injected can be increased; and after increasing the amount of water injected, the amount of water injected can be maintained under specified conditions.

[0113] Furthermore, according to the operating method of the biomass pellet grinding apparatus (100) of this embodiment, a new amount of water injection is determined based on the table differential pressure and the mill power. Therefore, for example, when the table differential pressure and the mill power are appropriate, the amount of water injection can be reduced under specified conditions, or the amount of water injection can be maintained under other specified conditions.

[0114] In a fourth aspect of the present disclosure, in the third aspect of the operating method of the biomass pellet grinding device, the biomass pellet grinding device (100) is provided with a carrier gas supply line (110) connected to the housing (11) at an inlet (11a) and supplying a carrier gas for transporting the crushed biomass pellets to the inside of the housing (11), and the amount of water injected is determined based on the mill inlet temperature, which is the temperature of the carrier gas near the inlet (11a), and the biomass supply amount, which is the supply amount of the biomass pellets.

[0115] According to the operating method of the biomass pellet grinding apparatus (100) of this embodiment, the amount of water injected is determined based on the mill inlet temperature and the amount of biomass supplied. Therefore, for example, when the amount of water injected can be increased, it is possible to determine whether the mill inlet temperature is below the upper limit temperature. Furthermore, if it is confirmed that the mill inlet temperature is below the upper limit temperature, the amount of water injected can be maintained if the biomass supply amount has reached the target value.

[0116] A biomass pellet grinding device according to a fifth aspect of the present disclosure includes a housing (11), a rotating table (12) provided inside the housing (11) and rotating about a central axis (L1), an annular member (62) provided on an upper surface of the rotating table (12) and centered on the central axis (L1), a fuel supply pipe (17) that supplies biomass pellets formed from biomass raw material to an area of ​​the rotating table (12) inside the annular member (62), a grinding roller (13) that grinds the biomass pellets by clamping them between the grinding roller (13) and the rotating table (12), and a water injection section (82) that injects water into the biomass pellets on the rotating table (12).

[0117] A boiler facility according to a sixth aspect of the present disclosure includes the biomass pellet crushing device (100) according to the fifth aspect, and a boiler that generates steam by burning the crushed biomass crushed by the biomass pellet crushing device (100) in a combustion device. [Explanation of symbols]

[0118] 1. Power plants 10 mil 11. Housing 11a Carrier gas inlet (inlet) 12 Grinding table (rotary table) 13 Crushing roller 14 Reducer 15 Mill motor (drive unit) 16 Rotary classifier 16a Blade 17 Fuel supply pipe 18 Classifier motor 19 Exit port (exit) 20 Fuel supply system 21 Banka 22 Conveyor section 23 Coal feeder motor 24 Downspout section 30 Blower section 30a Hot gas flow path 30b Cold gas flow path 30c Thermal Gas Damper 30d Cold Gas Damper 31 Primary air ventilator 34 Air preheater 40 Status detection unit 41 Bottom part 42 Ceiling 45 Journal Head 47 Support Arm 48 Support shaft 49 Pressing device 50 Control section 60 Rotary Valve 62 Dam Ring 63 Ring parts 64 Board material 65 volts 66 Cover 70 Biting part 72 Fuel layer 82 Water injection section 84 Water supply pipe 85 Flow meter 86 Flow Control Valve 100 Biomass pellet grinding equipment 110 Carrier gas supply line 120 Pulverized fuel supply line 200 Boiler 210 Furnace 220 Burner A1 Flow of pulverized fuel A2 Primary air flow L1 Rotation axis (center axis)

Claims

1. A method for adjusting a biomass pellet grinding device, comprising: The biomass pellet crushing device is Housing and a rotary table provided inside the housing and rotatable about a central axis; A drive unit that drives the rotary table; an annular member provided on an upper surface of the rotary table and centered on the central axis; A fuel supply pipe that supplies biomass pellets formed from a biomass raw material to an area of ​​the rotating table inside the annular member; A crushing roller that crushes the biomass pellets by pinching them between the rotating table and the crushing roller; A water injection unit that injects water into the biomass pellets on the rotating table; Equipped with The pressure difference between the space above and the space below the rotary table is defined as a table pressure difference, The pressure difference between the inlet of the housing into which a carrier gas for transporting the pulverized biomass pellets flows and the outlet of the housing from which the pulverized biomass pellets and the carrier gas are discharged is defined as a mill pressure difference; The driving force of the drive unit is the mill driving force. In this case, When the table differential pressure, the mill differential pressure, and the mill power during operation of the biomass pellet grinding apparatus are used as mill load indicators, determining a height dimension of the annular member based on at least one of the mill load indicators and an amount of water injected into the biomass pellets; How to adjust biomass pellet grinding equipment.

2. The biomass pellet crushing device is a carrier gas supply line connected to the housing at the inlet and supplying a carrier gas for transporting the pulverized biomass pellets to the inside of the housing; Equipped with The height dimension of the annular member is determined based on a mill inlet temperature, which is the temperature in the vicinity of the inlet during operation of the biomass pellet grinding device, a biomass supply amount, which is the amount of the biomass pellets supplied during operation of the biomass pellet grinding device, and a biomass remaining amount, which is the amount of the biomass pellets remaining on the rotary table after the biomass pellet grinding device is stopped. A method for adjusting a biomass pellet grinding device according to claim 1.

3. 1. A method for operating a biomass pellet grinding apparatus, comprising: The biomass pellet crushing device is Housing and a rotary table provided inside the housing and rotatable about a central axis; A drive unit that drives the rotary table; an annular member provided on an upper surface of the rotary table and centered on the central axis; A fuel supply pipe that supplies biomass pellets formed from a biomass raw material to an area of ​​the rotating table inside the annular member; A crushing roller that crushes the biomass pellets by pinching them between the rotating table and the crushing roller; A water injection unit that injects water into the biomass pellets on the rotating table; Equipped with The pressure difference between the space above and the space below the rotary table is defined as a table pressure difference, The pressure difference between the inlet of the housing into which a carrier gas for transporting the pulverized biomass pellets flows and the outlet of the housing from which the pulverized biomass pellets and the carrier gas are discharged is defined as a mill pressure difference; The driving force of the drive unit is the mill driving force. In this case, When the table differential pressure, the mill differential pressure, and the mill power are used as mill load indicators, determining a new amount of water to be injected based on at least one of the mill load indicators and the amount of water injected into the biomass pellets; Method for operating a biomass pellet grinding device.

4. The biomass pellet crushing device is a carrier gas supply line connected to the housing at the inlet and supplying a carrier gas for transporting the pulverized biomass pellets to the inside of the housing; Equipped with The amount of water injected is determined based on the mill inlet temperature, which is the temperature in the vicinity of the inlet, and the biomass supply amount, which is the supply amount of the biomass pellets. A method for operating the biomass pellet crushing apparatus according to claim 3.

5. Housing and a rotary table provided inside the housing and rotatable about a central axis; an annular member provided on an upper surface of the rotary table and centered on the central axis; A fuel supply pipe that supplies biomass pellets formed from a biomass raw material to an area of ​​the rotating table inside the annular member; A crushing roller that crushes the biomass pellets by pinching them between the rotating table and the crushing roller; A water injection unit that injects water into the biomass pellets on the rotating table; Equipped with Biomass pellet grinding equipment.

6. The biomass pellet crushing device according to claim 5 , A boiler that generates steam by burning the pulverized biomass pellets pulverized by the biomass pellet pulverizer in a combustion device; Equipped with Boiler equipment.

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