JP2009291721A - Method for determining maintenance timing of scraper in granulator of green pellet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for determining the maintenance timing of a scraper in a granulator of green pellets that never wants to inspect the amount of attritions of a scraper provided in the granulator of green pellets and can reduce the number of emergency shutdown of the granulator caused by anomaly such as breakage of scraper. <P>SOLUTION: The method for determining the maintenance timing of a scraper determining it is high time that maintenance should be performed on the scraper if a total evaluation score is less than a predetermined reference value by monitoring fouling generated in predetermined portions corresponding to the four scrapers 12, 13, 14, and 15 during actual granulation with the granulator 1, giving an evaluation score to each scraper corresponding to the thicknesses of each fouling monitored, and multiplying each given evaluation score by a predetermined weighting score by each predetermined portion, thereby finding the total evaluation score of these figures obtained is provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for determining a maintenance time of a scraper in a raw pellet granulator, for example, in the steelmaking field.

  In the firing process of ore pellet production, in order to obtain high productivity and high yield, high-quality raw pellets having good air permeability and not pulverizing at a low temperature (about 200 to 400 ° C.) are required. A drum-type granulator or a disk-type granulator (see, for example, Patent Document 1 and Non-Patent Document 1) is generally used for producing this raw pellet. Of these, the disk-type granulator is excellent in that it has a classification ability. In addition, the disk-type granulator has a plurality of scraping materials adhering to the inner and outer surfaces of the disk of this granulator in order to keep the actual volume of the disk constant and obtain raw pellets with a stable particle size. A scraper is installed.

However, the disk type granulator has the following problems.
1) In order to determine the maintenance time of the scraper, the amount of wear of the scraper had to be inspected. In order to carry out this inspection, the granulator had to be stopped frequently, and the productivity was greatly reduced.
2) Also, there is no clear standard for determining the maintenance time of the scraper, and the timing for stopping the granulator varies from worker to worker. In many cases, the granulator had to be stopped suddenly.
JP 2000-189776 A The Japan Iron and Steel Institute edition, “Third Edition, Steel Handbook Vol. 2, Steelmaking and Steelmaking” Maruzen, 1979

  The object of the present invention is that it is unnecessary to inspect the amount of wear of the scraper provided in the granulator for raw pellets, and the number of times that the granulator suddenly stops due to an abnormality such as breakage of the scraper can be reduced. An object of the present invention is to provide a method for determining the maintenance time of a scraper in a granulator for fresh raw pellets.

In order to achieve this object, the invention according to claim 1 of the present invention provides:
A method for determining the maintenance time of a scraper in a raw pellet granulator equipped with a plurality of scrapers,
(1) Test granulation is performed using the granulator or a granulator having the same specifications as the granulator (hereinafter collectively referred to as “granulator”), and each of the scrapers of the granulator The deposit generated at a predetermined location (hereinafter referred to as “each predetermined location”) of the granulator corresponding to the provided position is monitored, and the past granulation results are recorded for each monitored deposit. Based on the past granulation results, a predetermined evaluation score that increases as the thickness of the adhering material is thinner at each predetermined location determined in advance is assigned. Multiply the predetermined weighting points determined for each of the predetermined locations, to obtain the total evaluation score,
(2) A predetermined reference value for determining when to maintain the scraper from the relationship between the total evaluation score and the quality of finished pellets and / or the quality of product pellets is obtained in advance.
(3) The deposit generated at each predetermined location during actual granulation is monitored by the granulator, and the evaluation score is given according to the thickness of each monitored deposit,
(4) Multiplying each assigned evaluation score by the weighting score determined in advance for each predetermined location to obtain a total evaluation score, and when the total evaluation score falls below the predetermined reference value Is a method for determining the maintenance time of the scraper in the raw pellet granulator, wherein it is determined that it is time to maintain the scraper.

The invention according to claim 2 is the invention according to claim 1,
The granulator is disk-shaped;
The plurality of scrapers include a side scraper, a fixed scraper, and a bottom scraper.

The invention according to claim 3 is the invention according to claim 2,
Of the thickness of the deposit, the thickness of the deposit generated at each predetermined location of the granulator corresponding to the position where the side scraper and the fixed scraper are provided remains attached to each predetermined location. The thickness of the deposit generated at a predetermined location of the granulator corresponding to the position where the bottom scraper is provided is the thickness of the material scraped off by the bottom scraper.

The invention according to claim 4 is the invention according to claim 1,
The granulator is disk-shaped;
The plurality of scrapers include a side scraper, a fixed scraper, a bottom scraper, and a rim scraper.

The invention according to claim 5 is the invention according to claim 4,
Of the thickness of the deposit, the thickness of the deposit generated at each predetermined location of the granulator corresponding to the position where the side scraper, the fixed scraper, and the rim scraper are provided is set at each predetermined location. The thickness of the adhered matter generated at a predetermined position of the granulator corresponding to the position where the bottom scraper is provided is the thickness of the material scraped off by the bottom scraper. .

As described above, the present invention
A method for determining the maintenance time of a scraper in a raw pellet granulator equipped with a plurality of scrapers,
(1) Test granulation is performed using the granulator or a granulator having the same specifications as the granulator (hereinafter collectively referred to as “granulator”), and each of the scrapers of the granulator The deposit generated at a predetermined location (hereinafter referred to as “each predetermined location”) of the granulator corresponding to the provided position is monitored, and the past granulation results are recorded for each monitored deposit. Based on the past granulation results, a predetermined evaluation score that increases as the thickness of the adhering material is thinner at each predetermined location determined in advance is assigned. Multiply the predetermined weighting points determined for each of the predetermined locations, to obtain the total evaluation score,
(2) A predetermined reference value for determining when to maintain the scraper from the relationship between the total evaluation score and the quality of finished pellets and / or the quality of product pellets is obtained in advance.
(3) The deposit generated at each predetermined location during actual granulation is monitored by the granulator, and the evaluation score is given according to the thickness of each monitored deposit,
(4) Multiplying each assigned evaluation score by the weighting score determined in advance for each predetermined location to obtain a total evaluation score, and when the total evaluation score falls below the predetermined reference value Is a method of judging the maintenance time of the scraper in the raw pellet granulator characterized in that it is judged that it is time to maintain the scraper, and has the following effects.
1) Inspection of the amount of wear of the scraper is unnecessary, and the number of times that the granulator stops suddenly due to an abnormality such as breakage of the scraper can be reduced. Therefore, it is possible to suppress a decrease in productivity.
2) Raw pellets having a stable particle size can be obtained while productivity reduction can be suppressed as described above.

  Hereinafter, embodiments of the present invention will be described.

The determination method of the maintenance time of the scraper in the granulator of raw pellets according to the present invention,
A method for determining the maintenance time of a scraper in a raw pellet granulator equipped with a plurality of scrapers,
(1) Test granulation is performed using the granulator or a granulator having the same specifications as the granulator (hereinafter collectively referred to as “granulator”), and each of the scrapers of the granulator The deposit generated at a predetermined location (hereinafter referred to as “each predetermined location”) of the granulator corresponding to the provided position is monitored, and the past granulation results are recorded for each monitored deposit. Based on the past granulation results, a predetermined evaluation score that increases as the thickness of the adhering material is thinner at each predetermined location determined in advance is assigned. Multiply the predetermined weighting points determined for each of the predetermined locations, to obtain the total evaluation score,
(2) A predetermined reference value for determining when to maintain the scraper from the relationship between the total evaluation score and the quality of finished pellets and / or the quality of product pellets is obtained in advance.
(3) The deposit generated at each predetermined location during actual granulation is monitored by the granulator, and the evaluation score is given according to the thickness of each monitored deposit,
(4) Multiplying each assigned evaluation score by the weighting score determined in advance for each predetermined location to obtain a total evaluation score, and when the total evaluation score falls below the predetermined reference value Is characterized in that it is time to maintain the scraper.

Since it is the above structures, this invention has the following effects.
1) Inspection of the amount of wear of the scraper is unnecessary, and the number of times that the granulator stops suddenly due to an abnormality such as breakage of the scraper can be reduced. Therefore, it is possible to suppress a decrease in productivity.
2) Raw pellets having a stable particle size can be obtained while productivity reduction can be suppressed as described above.

  Hereinafter, the reason for the above configuration will be described in detail.

  The present inventor conducted earnest research on how to determine the maintenance time of the scraper without having to stop the disk-type granulator frequently and inspect the amount of wear of the scraper. . In addition, since there is no clear standard for determining the maintenance timing of the scraper, the timing for stopping the granulator varies from worker to worker, and abnormalities such as the scraper being damaged before the stop of inspection occur. We have conducted intensive research on how to reduce the frequency at which it must be stopped suddenly. That is, repeated research was conducted to determine how to determine the maintenance time of the scraper without reducing productivity as much as possible.

  As a result, the following solution clues were found by paying attention to the deposits generated at each predetermined location of the granulator during the test granulation using the granulator.

  That is, the actual volume of the granulator disk is kept constant, the raw material is stably rolled within a predetermined distance within the disk, and the stable particle size (the fine particles of the raw material and the fine deposits scraped off by the scraper) The conditions for obtaining a raw pellet of a predetermined particle size formed from (this raw pellet has a high drop resistance value, an appropriate porosity and a narrow porosity distribution width) were investigated. For that purpose, the deposits generated at each of the predetermined locations are as fine as possible (thin as thin), and the deposits may be scraped off by a scraper at locations where the amount of deposit is large. I found it to be important. In addition, the raw pellets granulated and finished in this way are also of good quality (high crushing strength and low pulverization rate when dropped) as the product pellets obtained through the firing process which is the next step after granulation. I got a correlation. Therefore, the remaining can maintain this state as much as possible during granulation and does not reduce the productivity (that is, 1. eliminate the stop of the granulator to inspect the amount of wear of the scraper. It has been found that the above-mentioned problem can be solved only by quantitatively determining the maintenance time of the scraper for reducing the frequency of suddenly stopping the granulator due to abnormalities such as breakage.

  Therefore, based on past granulation results, for a deposit generated at each predetermined location of the granulator, a predetermined evaluation score that increases as the thickness of the deposit decreases at each predetermined location. Decided in advance. Similarly, based on the past granulation record, it was decided to determine a predetermined weighting point according to the weight of the deposit determined for each of the predetermined locations. As described above, it has been found that the predetermined evaluation score and the predetermined weighting score are determined in advance, and the maintenance timing of the scraper can be determined quantitatively by using these scores. That is, the deposits generated at each predetermined location of the granulator during actual granulation are monitored, and the evaluation score is given according to the thickness of each monitored deposit, and each of the given evaluations is given. The score is multiplied by the weighting points determined in advance for each of the predetermined locations to obtain a total evaluation score. When the total evaluation score falls below a predetermined reference value, the scraper may be maintained. all right. This predetermined reference value is the total evaluation score and the finished quality of the raw pellet (this is evaluated from the shape, drop resistance, porosity, etc.) and / or the pellet after firing this raw pellet (so-called product) Pellets) quality (this is evaluated from crushing strength, powdering rate, etc.).

  By adopting a method for determining the maintenance time of the scraper according to the above evaluation criteria, it is no longer necessary to stop the granulator frequently and inspect the wear amount of the scraper. In addition, since the evaluation criteria became clear, the timing for stopping the granulator does not vary from worker to worker, and the frequency at which the granulator must be suddenly stopped has also decreased rapidly. Therefore, it became easy to obtain raw pellets having a stable particle diameter while suppressing a decrease in productivity.

  The disk-type granulator is provided with a plurality of scrapers, and generally, these scrapers are often composed of three scrapers, a side scraper, a fixed scraper, and a bottom scraper. However, the present invention is not limited to this, and the technical idea of the present invention can be applied to a configuration in which a rim scraper is further added to the rim portion of the disk of the granulator. This also makes it possible to determine the maintenance time of the scraper more comprehensively. As a result, it becomes easy to obtain raw pellets having a more stable particle diameter while suppressing a decrease in productivity. In addition, the granulator is not limited to a disk shape, and a scraper that scrapes off adhering raw materials adhering to the inner surface and inner and outer surfaces of the granulator in order to obtain raw pellets having a stable particle size. The installed configuration can be widely used.

  Further, for example, among the thicknesses of deposits generated during granulation using a disk-type granulator, each predetermined position of the granulator corresponding to the position where the side scraper, stationary scraper, and rim scraper are provided. The thickness of the deposit generated is determined by visually observing the deposit attached to each predetermined location. However, the thickness of the deposit generated at a predetermined location of the granulator corresponding to the position where the bottom scraper is provided cannot be known if it remains adhered. However, what has been scraped off by the bottom scraper can be visually observed, and thereby the thickness of the deposit can be determined.

  Further, the monitor of the adhered matter that remains adhered to each of the predetermined locations and the scraped adhered matter can be visually observed as described above. However, the present invention is not necessarily limited thereto. It is also possible to use various types of observation equipment. If these observation devices are used, it is possible to obtain various information based on the adhered material in addition to the thickness of the adhered material by various image processing, and use them after performing various signal processing.

  Hereinafter, an embodiment of a method for determining the maintenance time of a scraper in the raw pellet granulator of the present invention will be described with reference to the drawings.

(Example)
FIG. 1 is a block diagram showing an arrangement example of a disk-type granulator for explaining a method for determining a maintenance time of a scraper in the raw pellet granulator of the present invention, and FIG. 2 is a disk-type granulator shown in FIG. (A) is a front view thereof, and (b) is a schematic view of (a) seen from the direction of arrow A.

  In FIG. 1, 1 is a disk-type granulator, 2 is a hopper in which used raw materials are stored, 3 is a table feeder for supplying the used raw materials discharged from the hopper 2 to the disk-type granulator 1, and 4 is a disk. It is a roller screen for sieving raw pellets finished and discharged by the shape granulator 1. The raw pellets having a predetermined particle size screened by the roller screen 4 are sent to the firing step which is the next step.

  Next, the schematic configuration of the disk-type granulator shown in FIG. 1 will be described with reference to FIG.

  In FIG. 2, 10 is a disk portion having a diameter of 6 m of the disk-type granulator 1, 11 is a cylindrical rim portion having a depth of 0.76 m connected to the outer edge of the disk portion 10, and 12 is an inner surface of the rim portion 11. Side scraper for scraping off adhering material (specific gravity 2.5) adhering to the disk, 13 is a fixed scraper for scraping off adhering material adhering to the corner where the disk part 10 and the rim part 11 are connected, and 14 is a disk part. 10 is a bottom scraper for scraping off adhering raw material adhering to the upper surface of the rim, 15 is a rim scraper for scraping off adhering raw material adhering to the outer edge of the rim part 11, and 16 is an inclination for inclining the disk part 10 at a predetermined angle. A device 17 is a motor for rotating the disk unit 10 at a predetermined rotational speed. The disk portion 10 and the rim portion 11 constitute a pan.

  Next, the results of performing test granulation three times using eight disk-type granulators 1 (granulator numbers: # 1 to # 8) having the above specifications will be described.

  The eight disk-type granulators 1 were each tilted by the tilting device 16 so that the disk portion 10 was 45 °, and driven by the motor 17 so that the rotation speed of the pan was 10 ppm. Concentrate with an average particle size of about 50 μm as a raw material stored in the hopper 2 is supplied into the rotating bread via the table feeder 3, and the supplied raw material is supplied with water in the bread. The sample was rolled while being used as a binder, and test granulation was performed so that the target particle size of the raw pellets was about 12 mm. Moreover, the state of the deposit | attachment which generate | occur | produces on the said bread | pan during test granulation, and the raw pellet formed is visually monitored. Based on the results of monitoring during these test granulations, the deposits generated in the bread, the state of the formed raw pellets, and the pellets (so-called product pellets) after firing using the raw pellets were evaluated.

In addition, the predetermined location where the deposit | attachment of the bread | pan of the said granulator 1 corresponding to the position in which the said side scraper 12, the fixed scraper 13, the bottom scraper 14, and the rim scraper 15 were generated is hereafter respectively referred to as a side position and a fixed position. These are referred to as a bottom position and a rim position. In addition, in the evaluation, in accordance with the thickness of the deposit generated in advance at each of these four locations based on past granulation results, a predetermined evaluation score that increases as the thickness of the deposit decreases is as follows. It was provided as shown in Table 1. Moreover, as shown in Table 1 below, the thickness X of the deposit has a lower limit thickness on the equipment and an upper limit thickness on the operation for each predetermined portion.

Based on the criteria shown in Table 1 above, the evaluation given according to the thickness of the deposits generated at each of the four locations of the bread during the first, second and third test granulations The score results are shown in Table 2, Table 3 and Table 4, respectively.

Also, based on past granulation results, try to calculate the weight of the deposits at each of four locations when deposits with a thickness of 10 mm are attached to the side position, fixed position, bottom position and rim position, respectively. And 0.188 tons, 0.188 tons, 0.707 tons and 0.188 tons, respectively. Therefore, as shown in Table 5 below, a predetermined weighting score corresponding to the weight of these deposits was determined, and this weighting score was used for the subsequent calculations.

The weighted scores shown in Table 5 above are multiplied by the corresponding evaluation scores for each of the four locations shown in Table 2, Table 3, and Table 4, and the results of calculating the total evaluation scores are shown in Table 6, Table 7, and Table 8 shows.

Further, using the above eight granulators (granulator numbers: # 1 to # 8), the test pellet granulation is performed three times to evaluate the state of the raw pellets as the finished quality of the formed raw pellets. In doing so, criteria as shown in Table 9 below were set in advance, and predetermined evaluation scores were respectively determined. In the criteria shown in Table 9 below, the state of the raw pellet was expressed by three kinds of names. The meaning of each name is as follows.
Horse dung: Grains that the raw material used could roll in the bread piled up, or
Rolled up large deposits scraped by each creper
Large grain state Rolling: As soon as the raw material rolls in the pan, it is scraped off by each creper.
Grain that grows large while entraining the adhered matter
State Dumpling: As soon as the raw material rolls in the pan, it is scraped off by each creper.
The specified size is rounded while adhering to the surface the fine adhered matter
Grain size

  The results of evaluating the state of the raw pellet based on the criteria shown in Table 9 are shown in Table 6, Table 7 and Table 8, respectively.

  Moreover, the raw pellet formed by performing the above test granulation was fired in the firing step, which is the next step shown in FIG. 1, to produce a product pellet. FIG. 3 shows the results of examining the relationship between the pulverization rate when the product pellets were dropped onto concrete from a height of 15 m and the total evaluation score. Here, the powdering rate refers to the ratio of the number of particles having a particle size of 5 mm or less after dropping to the number before dropping. In FIG. 3, for example, when paying attention to the total evaluation score that gives an allowable powdering rate of 1% when the product pellets are used in a blast furnace, the score was found to be 45. Therefore, it was found that if this score is used as a predetermined reference value, the maintenance time of the scraper during actual granulation can be determined quantitatively.

  Further, FIG. 4 is a graph showing the total evaluation score of the deposits and the evaluation score of the raw pellets shown in Table 6, Table 7 and Table 8. From FIG. 4, it can be seen that there is a correlation as shown by a solid line between the total evaluation score of the deposit and the evaluation score of the raw pellet. When the predetermined reference value (45 points) indicated by the broken line in FIG. 4 is exceeded, the raw pellets generally have a better quality, and when below 45 points, the raw pellets generally have a worse quality. .

  Moreover, the result of having considered the total evaluation score of the deposit | attachment shown in the said Table 6, Table 7, and Table 8 for every granulator (granulator number: # 1- # 8) is shown in FIG. From FIG. 5, it is determined that granulator numbers # 1 and # 6 below the predetermined reference value (45 points) indicated by the broken line have already reached the time for maintenance of the scraper.

  Next, the results of evaluating the drop resistance and the porosity of the raw pellets that were actually granulated using the above granulator are shown in FIGS. 6 and 7, respectively. In FIG. 6, the one shown on the left side (indicated by black) among the vertical bars is that the raw pellets obtained by granulation not adopting the method for determining the maintenance time of the scraper of the present invention are dropped and the drop resistance is reduced. The result of the investigation (comparative example), the one shown on the right (indicated by white) is the result of dropping the raw pellet obtained by granulation using the method for judging the maintenance time of the scraper of the present invention and examining the drop resistance (Invention example). From this, it can be seen that the quality of raw pellets obtained by granulation using the method for determining the maintenance time of the scraper of the present invention is improved. In addition, in FIG. 7, among the vertical bars, the one shown on the left side (shown in black) is the porosity of raw pellets obtained by granulation that does not employ the method of determining the maintenance time of the scraper of the present invention. As a result of investigation (comparative example), what is shown on the right side (indicated by white) is the result of examining the porosity of raw pellets obtained by granulation using the method for determining the maintenance time of the scraper of the present invention (invention) Example). From this, it can be seen that the quality of raw pellets obtained by granulation employing the method for determining the maintenance time of the scraper of the present invention is improved.

  Next, the result of having evaluated the crushing strength of the pellet (what is called product pellet) after baking using the raw pellet obtained by performing actual granulation using the said granulator is shown in FIG. In FIG. 8, among the vertical bars, those indicated by black are the crushing strength of the product pellets obtained by calcining raw pellets obtained by granulation that did not employ the method for determining the maintenance time of the scraper of the present invention. As a result of examining the results (comparative example), the white display shows the crushing strength of the product pellets obtained by calcining raw pellets obtained by granulation using the method for determining the maintenance time of the scraper of the present invention. Result (invention example). From this, when raw pellets obtained by granulation employing the method for determining the maintenance time of the scraper of the present invention are used, an appropriate porosity and high crushing strength can be obtained in the product pellets after firing. It is done. From this, it can be seen that the granulation method employing the method for determining the maintenance time of the scraper of the present invention is effective.

In addition, before and after introducing the method for determining the maintenance time of the scraper in the raw pellet granulator of the present invention, the number of sudden stoppages of the granulator that occurred during actual granulation and the amount of production reduction due thereto were evaluated. The results are shown in Table 10 below.

  From the results shown in Table 10 above, according to the granulation employing the method for determining the maintenance time of the scraper of the present invention, the number of times that the granulator suddenly stops due to abnormalities such as breakage of the scraper is reduced ( It can be seen that this is also effective from the point of reduction to about 1/6) and the ability to suppress the reduction in production (decrease to about 1/13).

  In the present embodiment, an example in which the disk type granulator is provided with four scrapers, that is, a side scraper, a fixed scraper, a bottom scraper, and a rim scraper, is not necessarily limited thereto. For example, the technical idea of the present invention can be applied to a disk-type granulator provided with three scrapers, that is, a side scraper, a fixed scraper, and a bottom scraper. However, more preferably, when the method for determining the maintenance time of the scraper of the present invention is adopted in a disk granulator having four scrapers, the maintenance time of the scraper can be determined more comprehensively. As a result, it becomes easy to obtain raw pellets having a more stable particle diameter while suppressing a decrease in productivity. In addition, the granulator is not limited to a disk shape, and a scraper that scrapes off adhering raw materials adhering to the inner surface and inner and outer surfaces of the granulator in order to obtain raw pellets having a stable particle size. The installed configuration can be widely used.

  In the present embodiment, an example in which deposits generated during granulation are visually monitored has been described, but the present invention is not necessarily limited thereto. For example, various observation devices such as a CCD camera can be used. If these observation devices are used, it is possible to obtain various information based on the adhered material in addition to the thickness of the adhered material by various image processing, and use them after performing various signal processing.

It is a block diagram which shows the example of arrangement | positioning of the disk shape granulator for demonstrating the judgment method of the maintenance time of the scraper in the granulator of the raw pellet of this invention. 1A is a front view of the disk-type granulator shown in FIG. 1, and FIG. 2B is a schematic view of FIG. 1A viewed from the direction of arrow A. FIG. It is a graph which shows the result of having investigated the relationship between the powdering rate when dropping a product pellet, and the total evaluation score of a deposit. It is a graph which shows the relationship between the total evaluation score of a deposit | attachment, and the evaluation score of a raw pellet. It is a graph which shows the result of having considered the total evaluation score of the deposit | attachment for every granulator. It is a graph which shows the result of having evaluated the drop resistance of the raw pellet which performed actual granulation. It is a graph which shows the result of having evaluated the porosity of the raw pellet which performed actual granulation. It is a graph which shows the result of having evaluated the crushing strength of the product pellet after baking using the raw pellet obtained by performing actual granulation.

Explanation of symbols

1: Disc type granulator 2: Hopper 3: Table feeder 4: Roller screen 10: Disc unit 11: Rim unit 12: Side scraper 13: Fixed scraper 14: Bottom scraper 15: Rim scraper 16: Inclining device 17: Motor

Claims (5)

A method for determining the maintenance time of a scraper in a raw pellet granulator equipped with a plurality of scrapers,
(1) Test granulation is performed using the granulator or a granulator having the same specifications as the granulator (hereinafter collectively referred to as “granulator”), and each of the scrapers of the granulator The deposit generated at a predetermined location (hereinafter referred to as “each predetermined location”) of the granulator corresponding to the provided position is monitored, and the past granulation results are recorded for each monitored deposit. Based on the past granulation results, a predetermined evaluation score that increases as the thickness of the adhering material is thinner at each predetermined location determined in advance is assigned. Multiply the predetermined weighting points determined for each of the predetermined locations, to obtain the total evaluation score,
(2) A predetermined reference value for determining when to maintain the scraper from the relationship between the total evaluation score and the quality of finished pellets and / or the quality of product pellets is obtained in advance.
(3) The deposit generated at each predetermined location during actual granulation is monitored by the granulator, and the evaluation score is given according to the thickness of each monitored deposit,
(4) Multiplying each assigned evaluation score by the weighting score determined in advance for each predetermined location to obtain a total evaluation score, and when the total evaluation score falls below the predetermined reference value Is a time for maintenance of the scraper, and a method for determining the maintenance time of the scraper in the raw pellet granulator. The granulator is disk-shaped;
2. The method for determining a maintenance time of a scraper in a raw pellet granulator according to claim 1, wherein the plurality of scrapers include a side scraper, a fixed scraper, and a bottom scraper.   Of the thickness of the deposit, the thickness of the deposit generated at each predetermined location of the granulator corresponding to the position where the side scraper and the fixed scraper are provided remains attached to each predetermined location. The thickness of the deposit generated at a predetermined position of the granulator corresponding to the position where the bottom scraper is provided is the thickness of the scraped material scraped off by the bottom scraper. A method for judging the maintenance time of a scraper in the raw pellet granulator described in 1. The granulator is disk-shaped;
The method of determining a maintenance time of a scraper in a raw pellet granulator according to claim 1, wherein the plurality of scrapers include a side scraper, a fixed scraper, a bottom scraper, and a rim scraper. Of the thickness of the deposit, the thickness of the deposit generated at each predetermined location of the granulator corresponding to the position where the side scraper, the fixed scraper, and the rim scraper are provided is set at each predetermined location. The thickness of the adhered material generated at a predetermined position of the granulator corresponding to the position where the bottom scraper is provided is the thickness of the material scraped off by the bottom scraper. 5. A method for determining a maintenance time of a scraper in a raw pellet granulator according to claim 4.

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