JP2007185570A - Vertical roller mill, grinding method using vertical roller mill - Google Patents

Abstract

An object of the present invention is to provide a vertical roller mill capable of stably biting an object to be pulverized between a pulverizing roller and a pulverizing table even when the moisture content of the object to be pulverized is not suitable.
A vertical roller mill according to the present invention includes a lift device 40 that lifts a pulverizing roller 23 in a direction away from the pulverizing table 22; and occurrence of defective biting of an object to be pulverized between the pulverizing table 22 and the pulverizing roller 23. Detecting means 70 for detecting the lifting device 40 and the pressure device 27 so as to lift at least one of the plurality of grinding rollers 23 when the detection means 70 detects the occurrence of a biting failure of the object to be crushed. And control means 50 for controlling. With such a configuration, even if the moisture content of the object to be crushed is not suitable, the object to be pulverized can be stably caught between the raised crushing roller 23 and the crushing table 22.
[Selection] Figure 3

Description

  The present invention relates to a vertical roller mill and a pulverizing method using the same, and more particularly to a vertical roller mill for stabilizing the biting of an object to be pulverized between a pulverizing roller and a pulverizing table, and a pulverizing method using the vertical roller mill.

  The pulverized coal machine is a device for pulverizing and pulverizing a material to be crushed, such as petroleum coke, which is boiler fuel of a thermal power generation facility, before supplying it to the boiler. By pulverizing fuel such as petroleum coke with this pulverized coal machine, fuel in a state of being easily pulverized and combusted can be supplied to the boiler.

  A vertical roller mill is used as a pulverizer for pulverizing an object to be pulverized like the pulverized coal machine. The vertical roller mill includes a crushing table that rotates in a horizontal plane, and a plurality of crushing rollers that are pressed on the crushing table and rotate following the rotation of the crushing table. The material to be crushed can be bitten into the pulverized portion between the two and crushed.

  However, in the vertical roller mill that pulverizes the object to be pulverized such as solid fuel in this way, there is a case in which the fuel (object to be pulverized) is poorly caught in the pulverizing portion between the pulverizing table and the pulverizing roller. This poor biting is a phenomenon in which the fuel supplied on the crushing table slips without being bitten between the crushing table and the crushing roller, resulting in vibrations in the crushing part. . When such a biting failure occurs, the pulverizing function of the vertical roller mill as a pulverized coal machine is not performed, so fuel is not supplied to the boiler and power generation stops, so it is necessary to take some measures. .

  For example, Patent Document 1 discloses a technique for dealing with such a failure to bite the object to be pulverized in order to prevent the object to be slid between the pulverization roller and the pulverization table from slipping. A vertical roller mill having a reduction control mechanism that moves up and down is described.

  Further, in Patent Document 2, in order to prevent vibration in the pulverizing section in the vertical roller mill, when the supply amount of the material to be pulverized is small and the classification particle size of the classifier is small, the load of the pulverizing roller by the pressure device is described. However, a pulverization method is described in which the pulverization roller is controlled to be smaller than its own weight and in the direction opposite to the direction of its own weight.

Japanese Utility Model Publication No. 62-140947 JP-A-6-320028

  However, as described in the above-mentioned conventional patent document 1, in the method in which the pulverizing roller is periodically moved up and down, the transport amount of the fuel (pulverized coal etc.) pulverized by pulverization pulsates, so the fuel in the boiler There was a problem that the combustion of the boiler became unstable, affecting the operation of the boiler.

  In addition, as a result of intensive studies by the inventors of the present application, in a vertical roller mill, when the moisture content of the material to be pulverized is not within the range suitable for pulverization, for example, the moisture content of the pulverized fuel is less than 4% by mass and dried. If the water content is greater than 11% by mass and the water content is high, the grinding between the grinding table and the grinding roller is necessary when starting up the vertical roller mill or changing the fuel supply amount. It was found that poor fuel biting (slip, vibration) was likely to occur in the part. That is, when the amount of water in the fuel is high and low, the frictional resistance for biting between the crushing roller and the crushing table becomes small, so that the fuel cannot slip into the crushing part and slips. As a result, a clean bed of fuel cannot be formed on the crushing table, so that a slip phenomenon occurs between the crushing table and the crushing roller, and vibration is generated in the crushing unit.

  In this regard, in the method of Patent Document 2 described above, when the moisture content of the fuel is less than 4% by mass or greater than 11% by mass as described above, the fuel is surely placed between the grinding roller and the grinding table. There was a problem that could not be bitten.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a space between the grinding roller and the grinding table even when the water content of the material to be ground is not suitable. It is an object of the present invention to provide a new and improved vertical roller mill capable of stably biting an object to be ground and a grinding method using the same.

  In order to solve the above problems, according to one aspect of the present invention, there are provided a pulverizing table that rotates in a horizontal plane, a plurality of pulverizing rollers that are arranged on the pulverizing table at predetermined intervals along the rotational direction, and a pulverizing roller. There is provided a vertical roller mill that includes a pressurizing device that presses against a pulverizing table and pulverizes an object to be crushed between the pulverizing table and the pulverizing roller. The vertical roller mill includes a lift device that lifts the pulverizing roller away from the pulverizing table; a detecting unit that detects the occurrence of a biting failure of an object to be pulverized between the pulverizing table and the pulverizing roller; And a control means for controlling the lift device and the pressure device so as to lift at least one of the plurality of pulverizing rollers when occurrence of a biting failure of the pulverized material is detected.

  With this configuration, when the occurrence of a biting failure of the object to be crushed (for example, slip of the object to be crushed, vibration of the vertical roller mill, etc.) is detected, at least one of the plurality of pulverizing rollers is lifted by the lift device. It is done. For this reason, during normal times when there is no biting failure, the pulverized material is crushed by pressing multiple crushing rollers against the crushing table. The object to be crushed can be forcibly bitten between the raised crushing roller and the crushing table. Therefore, even when the moisture content of the object to be pulverized is not suitable, the object to be pulverized can be stably caught between the pulverization roller and the pulverization table.

  The detecting means includes a vibrometer that detects a vibration value representing a magnitude of vibration generated in the vertical roller mill during the crushing operation; and a vibration value detected by the vibrometer is greater than or equal to a predetermined reference vibration value that is set in advance. In this case, a determination unit that determines that the biting failure of the object to be crushed has occurred may be included. Thereby, it is possible to preferably detect the occurrence of the biting failure by using the vibration value correlated with the presence or absence of the biting failure.

  The detection means includes a detector that detects a load value representing a load of a driving device that rotates the crushing table during the crushing operation; and a case where the detected load value is equal to or less than a predetermined reference load value that is set in advance. And a determination unit that determines that the biting failure of the object to be crushed has occurred. Thereby, it is possible to suitably detect the occurrence of the biting failure using the load value correlated with the presence or absence of the biting failure.

  Further, the control means may control the lift device and the pressure device so as to alternately lift a plurality of pulverizing rollers when the detection means detects a biting failure of the object to be crushed. By alternately moving up and down a plurality of pulverizing rollers in this way, the pulverization operation can be continued to be pulverized by other pulverization rollers that have not been lifted, so that the pulverized object from the vertical roller mill can be pulverized. The pulsation of the supply amount of fine powder can be suppressed.

  In order to solve the above problems, according to another aspect of the present invention, a grinding table that rotates in a horizontal plane, and a plurality of grinding rollers that are arranged on the grinding table at predetermined intervals along the rotational direction; There is provided a pulverization method using a vertical roller mill having a pressure device that presses the pulverization roller toward the pulverization table and a lift device that lifts the pulverization roller away from the pulverization table. In this pulverization method, a pulverization step is performed in which a pulverization roller is pressed against a pulverization table by a pressure device while rotating the pulverization table so that an object to be pulverized is crushed between the pulverization table and the pulverization roller. In the invention, when the occurrence of a biting failure of the object to be crushed between the crushing table and the crushing roller is detected, at least one of the crushing rollers is lifted by a lift device.

  With this configuration, in the pulverization process, in normal times when no biting failure occurs, the pulverized material is pulverized by pressing a plurality of grinding rollers against the pulverization table. The crushing operation can be continued while the roller is lifted and the object to be crushed is forcibly caught between the raised crushing roller and the crushing table. Therefore, even if the water content of the material to be crushed is not suitable, the material to be crushed between the crushing roller and the pulverizing table can be pulverized to stably supply fine powder of the material to be crushed.

  Further, a vibration value indicating the magnitude of vibration generated in the vertical roller mill in the pulverization step is detected, and when the detected vibration value is equal to or greater than a predetermined reference vibration value set in advance, or in the pulverization step A load value representing the load of the driving device that rotates the table is detected, and when the detected load value is equal to or less than a predetermined reference load value that is set in advance, it is determined that the biting failure of the object to be crushed has occurred. You may make it do. Thereby, it is possible to suitably detect the occurrence of the biting failure by using the vibration value and / or the current value correlated with the presence or absence of the biting failure.

  Further, when the biting failure of the object to be pulverized is detected, the object to be pulverized may be pulverized while alternately lifting a plurality of pulverizing rollers by a lift device. Thus, the pulverization operation can be continued and the pulverized material can be pulverized by another pulverizing roller that has not been lifted, so that the pulsation of the supply amount of the fine powder of the pulverized material from the vertical roller mill can be suppressed.

  Further, when the above-mentioned crushing failure of the object to be crushed is no longer detected, the lifting operation of the crushing roller by the lift device is stopped, and all the crushing rollers are pressed toward the crushing table by the pressure device and the object to be crushed. You may make it grind | pulverize. As a result, when the biting failure is improved by the lifting operation of the crushing roller, the crushing roller lifting operation is stopped and all the crushing rollers are pressed toward the crushing table to resume normal crushing operation. .

  In order to solve the above problems, according to another aspect of the present invention, a grinding table that rotates in a horizontal plane, and a plurality of grinding rollers that are arranged on the grinding table at predetermined intervals along the rotational direction; There is provided a pulverization method using a vertical roller mill having a pressure device that presses the pulverization roller toward the pulverization table and a lift device that lifts the pulverization roller away from the pulverization table. This crushing method includes (1) a step of lifting a part or all of a plurality of crushing rollers by a lift device at the start of a vertical roller mill; and (2) rotating the crushing table for a predetermined period on the crushing table. (3) starting to supply a new object to be crushed on the crushing table and all crushing by a pressure device; And a step of pressing the roller toward the pulverizing table to start pulverizing the object to be crushed between the pulverizing table and the pulverizing roller.

  With this configuration, at the time of starting up the vertical roller mill, before supplying a new object to be crushed, at least one crushing roller is lifted and the object to be crushed by the centrifugal force of the rotation of the crushing table is removed from the crushing roller and the crushing table. The crushing roller can be lowered at the stage where it is bitten between the crushing and crushing can be started. Therefore, even when the moisture content of the material to be crushed is not suitable, the material to be crushed is caught between the grinding roller and the pulverization table and pulverized appropriately, so that the fine powder of the material to be crushed can be stably stabilized. Can supply.

  As described above, according to the present invention, even if the moisture content of the object to be pulverized is not suitable, the object to be pulverized can be stably caught between the pulverizing roller and the pulverizing table.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
The vertical roller mill according to the first embodiment of the present invention will be described below. In the following embodiment, an example in which a vertical roller mill is applied to a pulverized coal machine of a thermal power generation facility and petroleum coke is used as a material to be pulverized will be described. It is not limited to examples.

  First, with reference to FIG. 1, the outline | summary of the thermal power generation equipment (thermal power generation plant) concerning this embodiment is demonstrated. FIG. 1 is a schematic diagram showing an outline of the thermal power generation facility according to the present embodiment.

  As shown in FIG. 1, in a thermal power generation facility, petroleum coke, which is a fuel for power generation (hereinafter sometimes simply referred to as “fuel”), is transported to a raw material yard 1 and stored, and then transport trailer. It is transported to the power plant. This petroleum coke is charged into the raw material receiving hopper 2 and stored in a bunker 3 disposed at the top of a vertical roller mill 5 which is a pulverized coal machine. The petroleum coke stored in the bunker 3 is supplied into the vertical roller mill 5 at any time by the coal feeder 4, and is pulverized and pulverized by the vertical roller mill 5. The fine powder of petroleum coke pulverized by the vertical roller mill 5 is blown into the boiler 6 together with air and burned in the boiler 6. The boiler 6 receives water supply from the condensate pump 7 and the water supply pump 8, and generates water vapor by boiling the supplied water by heat generated when the fine powder of the petroleum coke is burned by a burner. . The exhaust gas from the boiler 6 at the time of combustion is purified by a soot treatment facility 12 including a denitration facility 9, an electrostatic precipitator 10, a desulfurization facility 11, and the like, and discharged to the atmosphere. On the other hand, the steam generated by the boiler 6 is transferred from the boiler 6 to the turbine generator 13, and the turbine generator 13 rotates the turbine with the steam to generate electric power. During this power generation, the turbine generator 13 is cooled by the cooling water supplied from the cooling tower 14 via the circulating water pump 15. The electric power generated by the turbine generator 13 is transmitted to the outside from the transmission tower 18 via the main transformer 16 and the circuit breaker 17.

  As described above, in the thermal power generation facility according to the present embodiment, the vertical roller mill 5 has a function of pulverizing, for example, petroleum coke as fuel for the boiler 6 as an object to be crushed and supplying it to the boiler 6. The saddle type roller mill 5 will be described in detail below.

  Next, the vertical roller mill 5 according to the present embodiment will be described with reference to FIG. FIG. 2 is a partially cutaway front view showing the configuration of the vertical roller mill 5 according to the present embodiment.

  As shown in FIG. 2, the vertical roller mill 5 includes a crushing table 22 that rotates in a horizontal plane below a crushing space surrounded by a substantially cylindrical housing 21 including an upper housing 21a, an intermediate housing 21b, and a lower housing 21c. A plurality of (three in the figure) crushing rollers 23 arranged on the crushing table 22 at predetermined intervals along the rotation direction are arranged.

  The crushing table 22 has a substantially circular dish shape whose outer peripheral edge protrudes upward, and a table liner 22 a for wear prevention is disposed on the upper surface of the crushing table 22. Further, in the center of the crushing table 22, a substantially tapered receiving portion 22b protruding upward is provided.

  Below the vertical roller mill 5, a motor 24 and a speed reducer 25, which are driving devices for rotating the crushing table 22, are disposed. By transmitting the driving force generated by the motor 24 to the crushing table 22 via the speed reducer 25, the crushing table 22 has a predetermined low speed around a rotating shaft (not shown) extending in the vertical direction. It rotates horizontally (for example, 50 rpm).

  Each crushing roller 23 is rotatably and swingably supported by a roller support device 26 including a roller journal. The roller support device 26 is connected to a pressurizing device 27 configured by, for example, a hydraulic loader. The pressure device 27 applies a load that presses the grinding roller 23 downward toward the grinding table 22 via the roller support device 26. With this configuration, the crushing roller 23 rotates in accordance with the rotation of the crushing table 22 that rotates horizontally as described above while being pressed against the crushing table 22 with a predetermined load with the object to be crushed. Even when the crushing roller 23 is pressed to the lowest position, a gap (clearance) having a predetermined dimension (for example, 3 to 5 mm) is generated between the crushing table 22 and the crushing roller 23. Thereby, since the crushing roller 23 and the crushing table 22 are not in direct contact with each other, damage to both can be prevented. The present embodiment is characterized in that each roller support device 26 is connected to a lift device (not shown in FIG. 2) for lifting the crushing roller 23. Details thereof will be described later. To do.

  In the housing 21, a fixed classifier 28 is disposed above the crushing roller 23, and the lower end of a substantially cylindrical coal supply pipe 29 is provided inside the fixed classifier 28. It is arranged. The upper end of the coal supply pipe 29 is connected to the coal feeder 4 (see FIG. 1), and the fuel (petroleum coke) as the material to be crushed is supplied from the coal feeder 4 into the vertical roller mill 5. It functions as a fuel supply pipe. Further, a rotary separator 30 and a rotary separator blade 31 are disposed so as to surround the coal supply pipe 29, and the rotary separator 30 is driven by a rotary separator driving motor 32. In addition, an outlet port 33 is provided at the upper portion of the upper housing 21a for supplying fine powder obtained by pulverizing the object to be pulverized to the boiler 6 (see FIG. 1).

  Next, the pulverizing operation of the vertical roller mill 5 configured as described above will be described. During the pulverization operation, the material to be crushed (petroleum coke) is supplied from the coal feeder 4 through the coal supply pipe 29 into the housing 21 of the vertical roller mill 5. The material to be crushed falls on the receiving portion 22b in the center of the pulverizing table 22, and then moves on the pulverizing table 22 toward the outer peripheral portion by the centrifugal force generated by the rotation of the pulverizing table 22, and is pulverized with the pulverizing roller 23. It is bitten between the table 22 and pulverized and pulverized. At this time, when an object to be crushed is caught between the pulverizing roller 23 and the pulverizing table 22, the pulverizing roller 23 is, for example, 10 upwards from the pulverizing table 22 even when pressed by a pressure device 27 with a predetermined load. It is lifted until it is separated by about -15 mm, and is rotated following the rotation of the grinding table 22.

  Further, during the pulverizing operation, hot air is sent into the lower housing 21c from the air supply port 34, and this hot air is blown up from an air throat between the outer peripheral portion of the pulverizing table 22 and the inner peripheral portion of the housing 21c. . The fine powder of the material to be pulverized as described above on the pulverization table 22 is dried while rising in the housing 21 by the flow of the hot air. The fine powder conveyed to the upper part of the housing 21 falls by gravity in order from the coarser (primary classification), while the fine powder further raised is further classified by the fixed classifier 28 and the rotary separator blade 31 ( The fine powder having a predetermined particle size or less is transported to the boiler 6 from the outlet port 33. In addition, the granular material having a predetermined particle size or more that has been screened off by the secondary classification by the fixed classifier 28 or the like falls on the crushing table 22 and is newly supplied into the housing 21 from the coal supply pipe 29. It is pulverized again together with the material to be crushed. In this way, pulverization and classification are repeated.

  The schematic configuration and operation of the vertical roller mill 5 according to the present embodiment have been described above. In the vertical roller mill 5, as described above, an object to be crushed (for example, petroleum coke) does not bite well into the pulverized portion between the pulverizing table 22 and the pulverizing roller 23, and a biting failure may occur. In particular, when the moisture content of the object to be pulverized is not within a numerical range suitable for pulverization (for example, 4 to 11% by mass), that is, when the moisture content is as small as less than 4% by mass (for example, It has been found that when the moisture content is greater than 11% by mass (when the object to be crushed is excessively wet), poor biting frequently occurs. This is because the object to be crushed whose moisture content is not in the appropriate numerical range has a low frictional resistance for biting between the pulverizing table 22 and the pulverizing roller 23 and therefore slips and cannot be bitten properly. . When such a biting failure occurs and the object to be crushed is not crushed, a large vibration is generated in the pulverized portion of the vertical roller mill 5, and the operation of the vertical roller mill 5 must be stopped. As a result, the operation of the boiler 6 is stopped and the power generation of the thermal power generation facility is stopped.

  The reason why the water content of the material to be crushed is high as described above is that, for example, the petroleum coke as the material to be crushed gets wet in the raw material yard 1 or the oil coke conveyed to the raw material yard 1 The water content is originally high. The reason why the moisture content of the material to be crushed is low is, for example, that petroleum coke as the material to be crushed is stored in the raw material yard 1 for a long time and dried, or the oil coke conveyed to the raw material yard 1 The moisture content is originally low.

  In order to deal with the above-described failure of the object to be crushed, the vertical roller mill 5 according to the present embodiment is provided with a lift device that lifts the pulverizing roller 23 away from the pulverizing table 22. When the vertical roller mill 5 is started up or when occurrence of a biting failure of the object to be crushed is detected during the crushing operation, the lift device, for example, alternately turns a plurality of crushing rollers 23 into a predetermined lift period (for example, A predetermined lift amount (for example, 5 to 30 mm) is lifted from the crushing table 22 by 5 to 20 seconds).

  The lift amount of the crushing roller 23 is within a physically possible range (for example, 5 to 30 mm) beyond the clearance when the clearance (initial gap) between the crushing roller 23 and the crushing table 22 is 3 to 5 mm, for example. ). Further, when the rotation speed of the crushing table 22 is, for example, 50 rpm, the crushing table 22 is emptied 4 to 17 times with respect to the crushing roller 23 lifted by lifting the crushing roller 23 for 5 to 20 seconds, for example. Will rotate.

  By lifting the pulverizing roller 23 in this way, the object to be crushed is forcibly engaged between the raised pulverizing roller 23 and the pulverizing table 22 by the centrifugal force generated by the rotation of the pulverizing table 22, and the pulverizing operation is performed. It can be stabilized.

  Here, with reference to FIG.3 and FIG.4, the lift apparatus 40 and the pressurization apparatus 27 of the vertical roller mill 5 concerning this embodiment are demonstrated in detail. FIG. 3 is an explanatory diagram showing the configuration of the lift device 40 and the pressure device 27 of the vertical roller mill 5 according to the present embodiment. FIG. 4 is an explanatory diagram showing operations of the lift device 40 and the pressure device 27 of the vertical roller mill 5 according to the present embodiment.

  As shown in FIG. 3, the roller support device 26 is rotatable about a support shaft 261 as a fulcrum. Thereby, the roller support device 26 supports the crushing roller 23 so as to be swingable in the vertical direction around the support shaft 261. Further, the upper projecting portion 262 of the roller support device 26 is rotatably connected to the piston rod 272 of the first hydraulic cylinder 271 that constitutes the pressurizing device 27. As shown in FIG. 4A, the first hydraulic cylinder 271 applies a predetermined pressing load to the roller support device 26 and rotates it downward to bring the crushing roller 23 toward the crushing table 22. It can be pressed with a load.

  On the other hand, the lower overhang portion 263 of the roller support device 26 is rotatably connected to the piston rod 402 of the second hydraulic cylinder 401 constituting the lift device 40. As shown in FIG. 4B, the second hydraulic cylinder 401 applies a lift load to the roller support device 26 and rotates it upward so that the crushing roller 23 is separated from the crushing table 22. Can be lifted by a lift amount (for example, 10 to 15 mm). Note that the piston rod 402 is not limited to the example shown in FIG. 3, and is only pressed against the end portion (the right end portion in FIG. 3) of the lower overhang portion 263 of the roller support device 26 without being a hinge structure. It does not matter as a structure.

  When the lift device 40 lifts the pressure device 27, the operation of the pressure device 27 is stopped, and a pressing load that causes the roller support device 26 to rotate downward is not applied. Similarly, when the pressure device 27 is pressed, the lift device 40 is stopped so as not to apply a lift load that rotates the roller support device 26 upward.

  As described above, the vertical roller mill 5 according to the present embodiment is characterized in that, in addition to the existing pressure device 27, the lift device 40 for lifting the crushing roller 23 is provided. In the present embodiment, the pressurizing device 27 and the lift device 40 are configured by two different hydraulic cylinders 271 and 401 as described above. Accordingly, there is an advantage that the lift device 40 can be installed only by adding the second hydraulic cylinder 271 and the like to the roller support device 26 of the existing vertical roller mill 5, and it is not necessary to modify other existing devices. Therefore, it can be easily applied to the existing vertical roller mill 5 without stopping the thermal power generation equipment line.

  However, the present invention is not limited to this example. For example, the pressurization device 27 and the lift device 40 may be configured by one hydraulic cylinder, and may be used for both pressing and lifting of the crushing roller 23. Thereby, when manufacturing the vertical roller mill 5 newly, the number of installation of a hydraulic cylinder etc. can be reduced and manufacturing cost can be reduced.

  Next, the control means 50 of the lift device 40 and the pressurizing device 27 will be described with reference to FIG.

  As shown in FIG. 3, the control means 50 for controlling the lift device 40 and the pressurizing device 27 includes, for example, a control unit 51 constituted by a microcontroller, a servo amplifier 52, a servo valve 53, and a predetermined pressure. A hydraulic unit 54 capable of delivering a large amount of oil, oil feeding pipes 55, 56 for feeding oil from the hydraulic unit 54 to the first hydraulic cylinder 271 of the pressurizing device 27 via the servo valve 53, and oil feeding pipes 55, 56. Open / close valves 57 and 58 provided respectively, oil supply pipes 59 and 60 for supplying oil from the hydraulic unit 54 to the second hydraulic cylinder 401 of the lift device 40 via the servo valve 53, and oil supply pipes 59 and 60 are provided. Open / close valves 61 and 62.

  The control unit 51 controls each unit in the control means 50. For example, the control unit 51 outputs a control signal for controlling operations of the pressurizing device 27 and the lift device 40 to the servo amplifier 52. The control unit 51 can also control the opening / closing of the on-off valves 57, 58, 61, 62.

  The servo amplifier 52 is supplied with a control signal from the control unit 51, a sensor (not shown) for detecting the position of the piston rod 272 of the first hydraulic cylinder 271, and the piston rod of the second hydraulic cylinder 401. A feedback signal representing each position is input from a sensor (not shown) that detects the position 402. The servo amplifier 52 transmits a servo valve control signal based on the control signal from the control unit 51 and the feedback signal, and controls the servo valve 53.

  The servo valve 53 adjusts the hydraulic pressure from the hydraulic unit 54 based on the servo valve control signal from the servo amplifier 52, and the first hydraulic cylinder 271 or the oil feeding pipes 59 and 60 are connected via the oil feeding pipes 55 and 56 or the oil feeding pipes 59 and 60. Supply to the second hydraulic cylinder 401.

  The operation of the control means 50 configured as described above will be described. When operating the pressurizing device 27, the control unit 51 opens the on-off valves 57 and 58, closes the on-off valves 61 and 62, and then switches the pressurizing device 27 through the oil feeding pipe 55. 1 Oil is fed to the hydraulic cylinder 271. As a result, the piston rod 272 of the first hydraulic cylinder 271 is pushed out hydraulically, so that the crushing roller 23 can be pressed against the crushing table 22.

  On the other hand, when the lift device 40 is operated, the control unit 51 opens the on-off valves 61 and 62, closes the on-off valves 57 and 58, and then closes the lift device 40 via the oil feeding pipe 59. 2 Oil is fed to the hydraulic cylinder 401. As a result, the piston rod 402 of the second hydraulic cylinder 401 is pushed out hydraulically, so that the grinding roller 23 can be lifted from the grinding table 22.

  As described above, when both the pressurizing device 27 and the lift device 40 are constituted by one hydraulic cylinder, for example, the first hydraulic pressure is supplied to the first hydraulic cylinder 271 via the oil supply pipe 56 and the first hydraulic pressure is supplied. By pulling the piston rod 272 of the cylinder 271, the grinding roller 23 can be lifted from the grinding table 22. In this way, the first hydraulic cylinder 271 constituting the pressurizing device 27 can also be used as the lift device 40, whereby the second hydraulic cylinder 401 can be omitted. Similarly, oil can be supplied to the second hydraulic cylinder 401 via the oil supply pipe 60 and the piston rod 402 of the second hydraulic cylinder 401 can be pulled in so that the crushing roller 23 can be pressed toward the crushing table 22. Become. In this way, the second hydraulic cylinder 401 constituting the lift device 40 can also be used as the pressurizing device 27, whereby the first hydraulic cylinder 271 can be omitted.

  Next, the configuration of the detection means 70 for generating a trigger signal for the control means 50 to control the lift device 40 will be described with reference to FIG.

  The detecting means 70 detects the occurrence of a biting failure of the object to be crushed between the pulverizing table 22 and the pulverizing roller 23 during the pulverizing operation by the vertical roller mill 5. In order to detect such a biting failure, for example, a method of detecting vibration generated in the vertical roller mill 5 during a pulverizing operation, a method of detecting a load of a motor 24 that is a driving device for rotating the pulverizing table 22, and There is.

  First, a method for detecting vibration generated in the vertical roller mill 5 will be described. When the object to be crushed is properly biting during the crushing operation by the vertical roller mill 5, fine vibration is stably generated in the vertical roller mill 5, and the vibration value of the vertical roller mill 5 (for example, the amplitude of vibration) ) Is small. On the other hand, when the object to be crushed slips and a biting failure occurs, large vibration is generated in the vertical roller mill 5 as described above, and the vibration value increases. Therefore, by detecting the vibration value of the vibration generated in the vertical roller mill 5, it is possible to detect whether or not a biting failure has occurred.

  Next, a method for detecting the load of the motor 24 will be described. When the object to be crushed is properly biting during the crushing operation by the vertical roller mill 5, a relatively large load is applied to the motor 24 that rotates the crushing table 22 at a predetermined speed. (For example, the current value of electric power (constant voltage) consumed by the motor 24) increases. On the other hand, when the object to be crushed slips and a biting failure occurs, the pulverization table 22 becomes nearly idle, so that a relatively small load is applied to the motor 24. As a result, the load of the motor 24 is reduced. The value (for example, the current value) becomes small. Therefore, by detecting the current value of the power consumed by the motor 24 as the load of the motor 24 that rotates the crushing table 22, for example, it is possible to detect the occurrence of a biting failure.

  From this point of view, as shown in FIG. 3, the detection means 70 according to the present embodiment includes, for example, a vibration meter 71 that detects a vibration value generated in the vertical roller mill 5 and a motor 24 that rotates the grinding table 22. An ammeter 72 that detects a current of consumed power and a determination unit 73 that determines whether or not the biting failure has occurred based on the detected vibration value and / or current value.

  The vibrometer 71 is mounted, for example, on the housing 21 (for example, the outer surface of the lower housing 21c) of the vertical roller mill 5, and continuously detects the vibration value (the amplitude of the vibration) in the housing 21 during the crushing operation. To do. Note that the vibrometer 71 can be installed at any location of the vertical roller mill 5. The ammeter 72 is an example of a detector that detects the load value of the motor 24 that rotates the crushing table 22, and continuously detects the current value of the motor during the crushing operation. The vibration value and current value detected by the vibrometer 71 and ammeter 72 are input to the determination unit 73.

  The determination unit 73 is configured by an arithmetic processing circuit or the like, and when the vibration value detected by the vibration meter 71 is a predetermined reference vibration value (for example, the vibration amplitude is 150 μm) or more, or When the current value detected by the ammeter 72 is equal to or less than a predetermined reference current value (for example, 18A) set in advance, it is determined that a biting failure of the object to be crushed has occurred. The reference vibration value and reference current value are determined according to the vibration value and current value detected during normal operation of the vertical roller mill 5, and the vibration value and current value detected during abnormal operation (when biting is defective). , Are set in advance.

  Thus, in the present embodiment, the determination unit 73 determines that a biting failure has occurred when either the detected vibration value or current value indicates an abnormal value. Thereby, the detection sensitivity of the occurrence of the biting failure can be increased. However, the present invention is not limited to this example, and when the detected vibration value is equal to or less than the reference vibration value and the detected current value is equal to or less than the reference current value, that is, both the detected vibration value and current value are detected. If the value indicates an abnormal value, the determination unit 73 may determine that a biting failure has occurred.

  When it is determined that a biting failure has occurred in this way, the determination unit 73 outputs a biting failure occurrence signal to the control unit 51 of the control means 50. Then, the control unit 51 controls the lift device 40 to operate to lift the plurality of crushing rollers 23 alternately in response to the biting failure occurrence signal. As a result, the object to be crushed can be caught between the raised crushing roller 23 and the crushing table 22 to improve the biting failure.

  For example, the determination unit 73 decreases from a state where the vibration value detected by the vibration meter 71 is equal to or higher than the reference vibration value to a normal vibration value less than the reference vibration value, and a predetermined period or more elapses. When the current value detected by the ammeter 72 rises from a state below the reference current value to a normal current value greater than the reference current value and a predetermined period or more has elapsed, It can also be determined that the biting failure has been improved. Note that the determination unit 73 is not limited to such an example, and the determination unit 73 determines that the detected vibration value has decreased to the normal vibration value and a predetermined period has elapsed, or that the detected current value is the normal current. When a predetermined period elapses after rising to the value, it may be determined that the biting failure of the object to be crushed has been improved.

  Thus, when the improvement of the biting failure is detected, the determination unit 73 outputs a biting failure improvement signal to the control unit 51 of the control means 50. Then, the control unit 51 controls to stop the lifting operation of the crushing roller 23 by the lift device 40 according to the biting failure improvement signal. As a result, the vertical roller mill 5 performs a normal crushing operation with all the crushing rollers 23 pressed against the crushing table 22.

  As described above, the detection unit 70 detects whether or not the object to be pulverized is caught between the pulverization table 22 and the pulverization roller 23 and outputs it to the control unit 50. Thus, the control means 50 performs the crushing operation by alternately lifting the plurality of crushing rollers 23 by the lift device 40 only during the period when the biting failure occurs during the crushing operation of the vertical roller mill 5. Can do.

  Next, the lifting operation of the grinding roller 23 during the grinding operation of the vertical roller mill 5 according to the present embodiment will be described in detail with reference to FIG. FIG. 5 is a timing chart for explaining the lifting operation of the grinding roller 23 during the grinding operation of the vertical roller mill 5 according to the present embodiment.

  As shown in FIG. 5, during the crushing operation by the vertical roller mill 5 (crushing process), when the biting failure does not occur and is normal, all the crushing rollers 23 are directed toward the crushing table 22 by the pressure device 27. While pressing, the object to be crushed is normally caught between the crushing table 22 and the crushing roller 23 and crushed. At this normal time, the current value detected by the ammeter 72 is stable at a normal current value (for example, 21 to 24A), and the vibration value (vibration amplitude) detected by the vibration meter 71 is normal. Stable vibration value (for example, 21 to 25 μm).

  In such a crushing operation, when a biting failure (slip of the object to be crushed, vibration of the vertical roller mill 5) occurs, the current value detected by the ammeter 72 is the reference current value (for example, 18A). The vibration value detected by the vibration meter 71 increases to the reference vibration value (for example, 150 μm) or more. Then, the detection means 70 detects the occurrence of a biting failure based on these vibration values and current values, and the control means 50 controls the lift device 40 and the pressure device 27 so that the three crushing rollers 23 (first to third crushing rollers 23) are alternately lifted by a predetermined lift period (10 to 20 sec).

  In the example of FIG. 5, the first crushing roller 23, the second crushing roller 23, the third crushing roller 23, the first crushing roller 23,... At the same time that the pulverizing roller 23 is lowered, the other pulverizing roller 23 is lifted.

  The reason why the pulverizing rollers 23 are alternately lifted is as follows. When all the pulverizing rollers 23 are lifted all at once, the pulverizing operation of all the objects to be pulverized stops, and the pulverized object fine powder (petroleum oil) This is because the fine powder of coke) is not supplied to the boiler 6. By alternately lifting the pulverizing rollers 23 as in the present embodiment, the pulverizing process is performed by the pulverizing rollers 23 that have not been lifted. Therefore, at least an amount of fine powder that allows normal operation of the boiler 6 is obtained. Can be continuously supplied.

  The order in which the crushing rollers 23 are alternately lifted is not limited to the example of FIG. 5 and can be set in various ways. For example, the second crushing roller 23 may be lifted after a predetermined waiting period has elapsed after the first crushing roller 23 has been lifted and lowered for a predetermined lift period. Alternatively, the first, first, second, second, third, third, first, and first crushing rollers 23 may be lifted alternately. Further, the first to third crushing rollers 23 may be alternately lifted in a random order.

  Even when the moisture content of the object to be pulverized is not in an appropriate range and is slippery by repeating the operation of alternately lifting and lowering the pulverizing roller 23 when the biting failure occurs as described above, the pulverizing table The object to be crushed can be forcibly bitten between 22 and the crushing roller 23 to stabilize the crushing operation. Therefore, it is possible to improve the biting failure and reduce the vibration, and to secure a sufficient amount of the object to be crushed by the vertical roller mill 5 and to continuously supply a sufficient amount of fine powder to the boiler 6. The lift period and lift amount for lifting the grinding roller 23 are not limited to the above example, and can be changed to appropriate values according to the moisture content and quality of the material to be ground. For this reason, the vertical roller mill 5 having the above-described configuration has a structure in which the lift period and the lift amount can be arbitrarily set.

  When the clogging failure is improved (the slip of the object to be crushed is eliminated and the vibration is reduced) by the lifting operation of the crushing roller 23, the current detected by the ammeter 72 is detected as shown in FIG. The value increases to a normal current value (for example, 21 to 24 A), and the vibration value detected by the vibration meter 71 decreases to a normal vibration value (for example, 21 to 25 μm). Then, the detection means 70 detects that the biting failure has been improved based on these vibration values and current values, and in response to this, the control means 50 causes the lift device 40 to move the crushing roller 23. Control is performed so that the lifting operation is stopped and the pressurizing operation by the pressurizing device 27 is restarted. Thereby, the crushing operation of the vertical roller mill 5 returns from the crushing operation while alternately raising the crushing rollers 23 to the normal crushing operation, and crushes all the crushing rollers 23 (first to third crushing rollers 23). While being pressed toward the table 22, the object to be pulverized normally is pulverized.

  As described above, with reference to FIG. 5, the crushing method for detecting a biting failure during the crushing operation of the vertical roller mill 5 and lifting the crushing roller 23 in response to the occurrence of the biting failure to improve the biting failure will be described. did.

  Next, when starting up the vertical roller mill 5 (including the initial start-up and restarting after the operation is stopped), the pulverizing roller 23 is lifted before the new pulverized material is supplied so that the pulverized material becomes the pulverizing roller. A pulverization method in which the pulverization roller 23 is lowered at the stage between the pulverization table 23 and the pulverization table 22 to start a normal pulverization operation will be described.

  When the vertical roller mill 5 is started, the moisture content of the material to be crushed is in an inappropriate range (less than 4% by mass and greater than 11% by mass), and of course, the moisture content is in an appropriate range (4 to 11% by mass). Even in some cases, the object to be crushed is slippery and is difficult to bite between the crushing table 22 and the crushing roller 23, so that the crushing operation is often not stable.

  Therefore, in the present embodiment, when the saddle type roller mill 5 is started, the lift device 40 lifts, for example, all the crushing rollers 23 by a predetermined lift amount and crushes between the raised crushing rollers 23 and the crushing table 22. The material is forcibly supplied, and then the crushing roller 23 is lowered to start the crushing operation in a state where the material to be crushed is suitably bitten.

  The operation flow of the pulverization method when starting up the vertical roller mill 5 will be described in detail. First, when the vertical roller mill 5 is started, the lift device 40 lifts all of the plurality of crushing rollers 23 by a predetermined lift amount (lifting process). Next, the crushing table 23 is rotated for a predetermined period, and the object to be crushed on the crushing table 23 is moved to the outer peripheral side of the crushing table 22 by centrifugal force. It is bitten in between (biting process). Thereafter, supply of a new object to be crushed from the coal supply pipe 29 onto the pulverizing table 22 is started, and all the pulverizing rollers 23 are lowered and pressed toward the pulverizing table 22 by the pressurizing device 27. The pulverization of the object to be crushed between the pulverization roller 23 is started (pulverization start step). As a result, when the vertical roller mill 5 is started, the object to be crushed can be suitably bitten and the pulverization operation can be started stably.

  In this embodiment, when the vertical roller mill 5 is started, all the crushing rollers 23 are lifted and the object to be crushed is bitten, and then all the crushing rollers 23 are lowered to start the crushing operation. , It is not limited to such an example. For example, at the time of startup, at least one crushing roller 23 may be lifted to bite an object to be crushed, and then the crushing operation may be started by lowering the raised crushing roller 23. Further, at the time of the start, the pulverization operation may be started by starting the supply of the object to be crushed while performing the operation of alternately lifting the plurality of pulverization rollers 23.

  Next, a description will be given of the results of experiments 1 to 3 in which the object to be pulverized is pulverized using the vertical roller mill 5 according to the present embodiment. In any of Experiments 1 to 3, the vertical roller mill 5 is a pulverized coal pulverizer for petroleum coke (model: Mitsubishi vertical mill, capacity: 12.8 t / h, fineness: 200 mesh (nominal size 75 μm) 95%, classification method) : Fixed / rotary classifier).

(Experiment 1)
Before the vertical roller mill 5 was started, the crushing roller 23 was lifted to secure a clearance of 5 mm between all the crushing rollers 23 and the crushing table 22. In this state, the pulverizing table 22 was rotated for 10 seconds, and the petroleum coke was reliably caught between the raised pulverizing roller 23 and the pulverizing table 22. Thereafter, supply of petroleum coke from the coal supply pipe 29 was started, and the crushing operation was started by lowering the crushing roller 23.

  As a result, even if the water content of petroleum coke is 4% by mass or 11% by mass, the vertical roller mill 5 is free from biting failure and slip phenomenon when starting up, and the vertical roller mill 5 has no problem. It was confirmed that it can be started.

(Experiment 2)
Before the vertical roller mill 5 was started, the crushing roller 23 was lifted to ensure a clearance of 30 mm between all the crushing rollers 23 and the crushing table 22. In this state, the pulverizing table 22 was rotated for 10 seconds, and the petroleum coke was surely caught between the raised pulverizing roller 23 and the pulverizing table 22. Thereafter, the supply of petroleum coke from the coal supply pipe 29 was started, and the crushing operation was started by lowering the crushing roller 23.

  As a result, even if the water content of petroleum coke is 3% by mass or 12% by mass, the vertical roller mill 5 can be prevented from being jammed or slipped at the start-up, and the vertical roller mill 5 can be used without any problem. It was confirmed that it can be started.

(Experiment 3)
When the load is changed during the operation of the vertical roller mill 5, if a clogging failure such as slip or vibration of petroleum coke occurs, the plurality of crushing rollers 23 are alternately turned by about 30 seconds for a lift amount of 30 mm. The crushing operation was performed while lifting.

  As a result, even if the moisture content of petroleum coke is 3% by mass or 14% by mass, the bite roller mill 5 is prevented from being bitten and slipping at the start-up, and the vertical roller mill 5 has no problem. It was confirmed that the grinding operation can be continued.

  According to the above experimental results, even when the bite roller mill 5 is started up and the load changes, the oil coke, which is the object to be crushed, may be caught by raising the pulverizing roller 23 so that the oil coke is suitable. It can be seen that it can be bitten.

The vertical roller mill 5 and the pulverizing method according to this embodiment have been described in detail above. According to this embodiment, when the vertical roller mill 5 is started, when the load is low, or when the load is changed, the object to be pulverized (slip of the object to be pulverized, vibration of the vertical roller mill 5) occurs. However, the object to be crushed can be forcibly bitten between the crushing roller 23 and the crushing table 22 by lifting the crushing roller 23. Therefore, the crushing operation can be continuously and stably performed without stopping the vertical roller mill 5. In particular, in this embodiment, when the vertical roller mill 5 is operating normally (when no biting failure occurs). Is characterized in that a normal crushing operation is performed by applying a rolling force to the plurality of crushing rollers 23, and the plurality of crushing rollers 23 are alternately lifted only when an abnormality occurs (when a biting failure occurs). As a result, the object to be crushed is caught between the pulverizing roller 23 and the pulverizing table 22, thereby eliminating the biting failure and vibration associated with the slip of the object to be crushed. Further, by alternately moving the crushing rollers 23 up and down, pulsation of the amount of pulverized petroleum coke (pulverized coal) conveyed can be suppressed, and fuel can be stably supplied from the vertical roller mill 5 to the boiler 6. For this reason, combustion of the pulverized coal in the boiler 6 can be stabilized and the boiler 6 can be prevented from stopping, so that power generation in the thermal power generation facility can be stably continued.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above embodiment, the vertical roller mill is applied to a pulverized coal machine of a thermal power generation facility, and an example of pulverizing petroleum coke as fuel for the boiler 6 as an object to be crushed has been described. It is not limited to examples. A vertical roller mill is a material to be crushed, for example, coal as a fuel for thermal power generation, PCI (pulverized coal injection) coal used as supplementary fuel in a blast furnace of an ironmaking plant, raw materials such as cement raw materials, chemical products, etc. It is also applicable when pulverizing the like.

  In the above-described embodiment, the detection means 70 detects the occurrence of a biting failure based on the vibration value of the vertical roller mill 5 and the load value (for example, current value) of the motor 24 that rotates the crushing table 22. The present invention is not limited to such an example. For example, the occurrence of a biting failure is detected based on the natural lift amount (different from the forced lift amount by the lift device 40) of each crushing roller 23 that accompanies the biting of the object to be crushed during the crushing motion. You can also

  That is, during normal crushing operation, an object to be crushed is caught between the crushing roller 23 and the crushing table 22, so that the crushing roller 23 is separated from the crushing roller 23 with the support shaft 261 of the roller support device 26 as a fulcrum. Rotate in the direction and lift naturally by the lift amount corresponding to the biting thickness of the object to be crushed. For this reason, when the natural lift amount is within an appropriate range, it is possible to determine that the crushing roller 23 has no biting failure and is normal, while the natural lift amount is However, if it is smaller than the predetermined reference lift amount, it can be determined that the crushing failure has occurred in the crushing roller 23.

  Therefore, a lift amount detector (not shown) for detecting the lift amount of each crushing roller 23 is provided, and when the lift amount detected by this lift amount detector is smaller than the reference lift amount, It may be determined that a biting failure has occurred in the roller 23 and the crushing roller 23 may be lifted for a predetermined time. As a result, it is possible to appropriately identify the crushing roller 23 in which the biting failure has occurred and lift only the crushing roller 23, so that the effect of the lifting operation of the crushing roller 23 can be improved.

  The present invention is applicable to a vertical roller mill for pulverizing an object to be crushed and a pulverization method using the same.

It is the schematic which shows the outline | summary of the thermal power generation equipment concerning the 1st Embodiment of this invention. It is a partially notched front view which shows the structure of the vertical roller mill concerning the embodiment. It is explanatory drawing which shows the structure of the lift apparatus and pressurization apparatus of a vertical roller mill concerning the embodiment. It is explanatory drawing which shows operation | movement of the lift apparatus and pressurization apparatus of a vertical roller mill concerning the embodiment. 6 is a timing chart for explaining the lifting operation of the grinding roller during the grinding operation of the vertical roller mill according to the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw material yard 2 Raw material receiving hopper 3 Bunker 4 Coal feeder 5 Vertical roller mill 6 Boiler 13 Turbine generator 21 Housing 22 Grinding table 23 Grinding roller 24 Motor 25 Reducer 26 Roller support device 27 Pressure device 28 Fixed classifier 29 Charging pipe 30 Rotary separator 31 Rotary separator blade 32 Rotary separator drive motor 33 Exit port 40 Lift device 50 Control means 51 Control part 70 Detection means 71 Vibrometer 72 Ammeter 73 Determination part 261 Support shaft 271 First hydraulic cylinder 272 Piston Rod 401 Second hydraulic cylinder 402 Piston rod

Claims (9)

A crushing table that rotates in a horizontal plane, a plurality of crushing rollers that are arranged on the crushing table at predetermined intervals along the rotation direction, and a pressure device that presses the crushing roller toward the crushing table, A vertical roller mill that pulverizes an object to be crushed between the pulverizing table and the pulverizing roller:
A lifting device that lifts the grinding roller away from the grinding table;
Detecting means for detecting occurrence of a biting failure of the object to be crushed between the pulverizing table and the pulverizing roller;
Control means for controlling the lift device and the pressure device to lift at least one of the plurality of pulverizing rollers when the detection means detects occurrence of a biting failure of the object to be crushed;
A vertical roller mill characterized by comprising: The detection means includes
A vibrometer for detecting a vibration value indicating the magnitude of vibration generated in the vertical roller mill during the crushing operation;
A determination unit that determines that a biting failure of the object to be crushed has occurred when a vibration value detected by the vibration meter is equal to or greater than a predetermined reference vibration value set in advance;
The vertical roller mill according to claim 1, characterized by comprising: The detection means includes
A detector for detecting a load value representing a load of a driving device for rotating the crushing table during a crushing operation;
A determination unit that determines that a biting failure of the object to be crushed has occurred when the detected load value is equal to or less than a predetermined reference load value set in advance;
The vertical roller mill according to claim 1 or 2, characterized by comprising:   The control means controls the lift device and the pressure device so as to alternately lift the plurality of pulverizing rollers when the detection means detects a biting failure of the object to be crushed. The vertical roller mill according to any one of claims 1 to 3. A crushing table that rotates in a horizontal plane, a plurality of crushing rollers disposed on the crushing table at predetermined intervals along the rotation direction, a pressure device that presses the crushing roller toward the crushing table, and the crushing A crushing method using a vertical roller mill having a lift device for lifting a roller away from the crushing table:
A pulverizing method in which the pulverizing roller is pressed against the pulverizing table by the pressure device while rotating the pulverizing table so that an object to be pulverized is pulverized between the pulverizing table and the pulverizing roller. In the step, when it is detected that the object to be pulverized between the pulverizing table and the pulverizing roller is caught, at least one of the pulverizing rollers is lifted by the lift device. A grinding method using a vertical roller mill. A vibration value representing the magnitude of vibration generated in the vertical roller mill in the crushing step is detected, and the detected vibration value is greater than or equal to a predetermined reference vibration value set in advance, or
In the pulverization step, a load value representing a load of a driving device that rotates the pulverization table is detected, and when the detected load value is equal to or less than a predetermined reference load value set in advance,
6. The pulverizing method using a vertical roller mill according to claim 5, wherein it is determined that a biting failure of the object to be crushed has occurred.   The pulverized object is pulverized while the plurality of pulverizing rollers are alternately lifted by the lift device when a biting failure of the pulverized object is detected. A grinding method using the vertical roller mill described.   When the biting failure of the object to be crushed is no longer detected, the lifting operation of the crushing roller by the lift device is stopped, and all the crushing rollers are pressed toward the crushing table by the pressure device. The pulverization method using the vertical roller mill according to any one of claims 5 to 7, wherein the pulverized material is pulverized. A crushing table that rotates in a horizontal plane, a plurality of crushing rollers disposed on the crushing table at predetermined intervals along the rotation direction, a pressure device that presses the crushing roller toward the crushing table, and the crushing A crushing method using a vertical roller mill having a lift device for lifting a roller away from the crushing table:
Lifting a part or all of the plurality of crushing rollers by the lifting device when the vertical roller mill is activated;
Rotating the pulverizing table for a predetermined period, and causing the object to be crushed on the pulverizing table to be caught between the raised pulverizing roller and the pulverizing table;
The supply of a new object to be crushed on the pulverizing table is started, and all the pulverizing rollers are pressed toward the pulverizing table by the pressure device, so that the object to be crushed between the pulverizing table and the pulverizing roller is pressed. Starting the pulverization of the pulverized product;
A crushing method using a vertical roller mill characterized by comprising:

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