JP7330786B2 - Method for operating pulverization system and method for producing powder - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing powder by pulverizing a pulverized raw material with a vertical pulverizer and a method for operating a pulverizing system used therefor.

BACKGROUND ART Conventionally, a vertical pulverizer is known as one type of pulverizer for drying and pulverizing pulverized raw materials. Examples of pulverized raw materials include cement raw materials and calcium carbonate. Patent Documents 1 and 2 disclose pulverizing systems including this type of vertical pulverizer.

Patent Document 1 discloses a closed-circuit crushing type crushing system. This pulverization system has a vertical pulverizer with a built-in classifier. When the pulverized raw material is pulverized by a pulverizer, a pulverized product containing coarse powder and fine powder is produced. Coarse powder is once discharged from the grinder and then re-supplied to the grinder for re-grinding. The fine powder passes through the classifier accompanied by the gas rising in the grinder, and is classified into fine powder and others by the classifier. The refined powder is discharged from the grinder together with the gas, collected by a dust collector, and then recovered as a product. The gas separated from the refined powder in the dust collector is returned to the crusher.

The pulverization system of Patent Document 2 includes a classifier independent from the vertical pulverizer. Fine powder among the pulverized products of the pulverizer is discharged from the pulverizer together with the gas bled from the pulverizer, and separated from the gas by the dust collector. The gas separated from the fine powder in the dust collector is returned to the crusher, and the fine powder is sent to the classifier by the conveyor. Coarse powder among the pulverized products of the pulverizer is sent to the classifier by the conveyor. The pulverized material sent to the classifier is classified into refined powder and others. The refined powder is recovered as a product by the subsequent dust collector, and the rest is returned to the pulverizer. In the pulverization system of Patent Document 2, since the pulverized material circulation system of the pulverizer and the gas circulation system of the pulverizer are independent, the amount of air extracted from the pulverizer and the classification air volume of the classifier are independent. can be adjusted.

JP-A-9-117685 JP 2018-202347 A

The present invention is a further development of the invention described in Patent Document 2, and its purpose is to use a closed circuit pulverizing system including a vertical pulverizer to produce refined powder (powder It is to provide a technology for manufacturing a body).

A method of operating a pulverization system according to one aspect of the present invention comprises:
A vertical pulverizer for pulverizing the pulverized raw material,
a pulverized material circulation path through which the pulverized material moves from the discharge port of the vertical pulverizer to the supply port;
a classifier provided in the pulverized material circulation path to separate the pulverized material into fine powder to be a product and coarse powder to be returned to the vertical pulverizer;
a passage connected to the exhaust port of the classifier;
a collector for collecting the refined powder accompanying the gas discharged from the classifier to the passage ;
a classifying fan that exhausts air from the classifier to the passage at a predetermined classifying air volume;
a bleed passage connected to the top of the vertical pulverizer;
a bleed fan that bleeds air from the vertical pulverizer to the bleed path at a set bleed air volume;
A method of operating a pulverizing system comprising a dust collector that separates fine powder from the bleed air of the vertical pulverizer and sends it to the pulverized material circulation path,
Determine the correlation between the amount of air extracted from the vertical pulverizer and the fineness of the refined powder to be recovered, estimate the amount of air extracted to obtain the desired fineness based on the correlation, and set the amount of extracted air to the above It is characterized in that it is set to a set bleed air volume.

Further, in the method for producing powder according to one aspect of the present invention, the raw material to be pulverized is supplied to a vertical pulverizer and pulverized, and air is extracted from the vertical pulverizer at a set extraction air volume to remove fine powder from the pulverized material. The fine powder is separated from the air stream and transported to a classifier by a transporter, the rest of the pulverized material is transported to the classifier by the transporter, and the powder is transported from the classifier to a predetermined amount. The pulverized material is classified into refined powder and coarse powder according to the set particle diameter by exhausting air at a classifying air volume , and the refined powder is air-flow-conveyed from the classifier to a collector and collected as a product by the collector. and returning the coarse powder from the classifier to the vertical pulverizer for re-pulverization. Then, the correlation between the bleed air volume from the vertical pulverizer and the fineness of the refined powder to be recovered is obtained, and based on the correlation, the bleed air volume at which the desired fineness is obtained is estimated, and the bleed air volume is estimated. is set as the set bleed air volume.

According to the method of operating the pulverizing system and the method of manufacturing powder, it is possible to obtain refined powder (powder) having an arbitrary fineness by changing the set amount of extraction air. That is, by changing the fineness of the refined powder to be obtained, it is possible to obtain a powder product according to the purpose of use. As a result, it is possible to improve the quality of the powder product.

According to the present invention, it is possible to provide a technology for producing refined powder (powder) with an arbitrarily adjusted fineness using a closed circuit pulverizing system including a vertical pulverizer.

FIG. 1 is a diagram showing the overall configuration of a pulverization system according to one embodiment of the present invention. FIG. 2 is a diagram showing the configuration of a second experimental apparatus that simulates a conventional pulverization system. FIG. 3 is a chart showing the correlation between the amount of air extracted from the vertical pulverizer and the fineness of the recovered refined powder. FIG. 4 is a chart showing a characteristic curve of the electric power consumption rate of the vertical pulverizer with respect to the amount of air extracted from the vertical pulverizer.

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the overall configuration of a pulverization system 1 according to one embodiment of the present invention.

The closed-circuit pulverizing system 1 shown in FIG. A connected gas circulation system 4 is provided.

[Vertical pulverizer 2]
The crusher 2 comprises a housing 21 forming a crushing chamber 20 in which the crushing of the raw material to be crushed takes place. Inside the housing 21, there are provided a rotary table 22 that rotates about a vertical axis of rotation, and a plurality of crushing rollers 23 that are pressed against the rotary table 22 by pressure means (not shown) and are driven to rotate. Below the housing 21, a mill motor 24 as a rotational drive source for the rotary table 22 and a speed reduction mechanism 25 for transmitting rotational power of the mill motor 24 to the rotary table 22 are provided. The crusher 2 does not incorporate a classifier.

A supply port 26 is provided at the top of the housing 21 . The pulverized raw material is introduced to the upper surface of the rotary table 22 through the supply port 26 . An air bleed port 27 is provided above the rotary table 22 and above the housing 21 . Through the air bleed port 27, the fine powder generated by the pulverization of the pulverized raw material is discharged along with the rising air current. A discharge port 28 is provided below the rotary table 22 . The pulverized material overflowing from the outer peripheral edge of the rotary table 22 is discharged to the outside of the pulverizer 2 through the outlet 28 . A hot air outlet 29 is provided around the outer circumference of the rotary table 22 . Hot air is blown upward into the pulverization chamber 20 from the hot air outlet 29 .

[Pulverized material circulation system 3]
The pulverized material circulation system 3 is configured to separate the refined powder to be the product from the pulverized material discharged from the discharge port 28 of the pulverizer 2 and return the pulverized material from which the refined powder is separated to the pulverizer 2. . The refined powder separated by the pulverized material circulation system 3 is recovered as a product.

The pulverized material circulation system 3 has a pulverized material circulation path 30 through which the pulverized material discharged from the pulverizer 2 moves from the discharge port 28 of the pulverizer 2 to the supply port 26 . A classifier 7 is provided in the pulverized material circulation path 30 . In this embodiment, since the pulverized material inlet 71 of the classifier 7 is positioned above the outlet 28 of the pulverizer 2, the conveyor 31 conveys the pulverized material upward from the outlet 28 to the pulverized material inlet 71. is provided in the pulverized material circulation path 30 . The conveying machine 31 according to this embodiment is a bucket elevator provided with a plurality of buckets (not shown).

A discharge port 28 of the crusher 2 is connected to a first inlet 31a of the carrier 31 via a passage 30a. The conveying machine 31 conveys pulverized materials introduced through a first inlet 31a and a second inlet 31b, which will be described later, upward, and discharges them from an outlet 31c. The outlet 31c of the carrier 31 is connected to the pulverized material inlet 71 of the classifier 7 via the passage 30b. A distribution damper (not shown) may be provided in the passage 30b connecting the conveying machine 31 and the classifier 7. FIG. A portion of the pulverized material may be transported directly to the supply port 26 of the pulverizer 2 by this distribution damper without going through the classifier 7 .

The classifier 7 classifies the supplied pulverized material into fine powder and coarse powder according to the set particle size. The set particle size of the "fine powder" is determined according to the particle size of the product to be collected. "Coarse powder" here means that of the pulverized material supplied to the classifier 7 that has a particle size larger than that of the refined powder. In this embodiment, an air classifier is adopted as the classifier 7 . However, the classifier 7 is not limited to an air classifier as long as it can classify the pulverized material into refined powder and other powders according to the particle size.

The pulverized material classified into coarse powder by the classifier 7 is discharged from the discharge port 72 . The discharge port 72 is connected to the feed port 26 of the crusher 2 via the passage 30c.

The pulverized material classified into refined powder by the classifier 7 is discharged from the exhaust port 73 by an air current. The exhaust port 73 is connected to the inlet of the collector 6 via the passage 64 . A classifying fan 66 is provided in an exhaust passage 65 of the collector 6 . The exhaust air volume of the classifying fan 66 is adjusted to a predetermined classifying air volume F2.

The collector 6 collects fine powder accompanying the gas discharged from the classifier 7 and separates the fine powder from the gas. In this embodiment, a bag filter is employed as the collector 6 . However, the collector 6 is not limited to a bag filter as long as it can collect refined powder accompanying the gas.

[Gas circulation system 4]
The gas circulation system 4 is configured to separate fine powder from the exhaust gas of the pulverizer 2 and return the gas from which the fine powder is separated to the pulverizer 2 as hot air.

The gas circulation system 4 has a gas circulation path 40 through which the gas extracted from the crusher 2 flows from the extraction port 27 of the crusher 2 to the hot air inlet 29a. The gas circulation path 40 is provided with a dust collector 41 that separates fine powder from the air extracted from the crusher 2 , an air extraction fan 42 , and a hot air supply source 43 that supplies hot air to the gas circulation path 40 . The exhaust air volume of the bleed fan 42 is adjusted to the bleed air volume F1.

The air bleed port 27 of the crusher 2 is connected to the inlet of the dust collector 41 via an air bleed passage 40a. The outlet of the dust collector 41 is connected to the hot air inlet 29a of the crusher 2 through the passage 40b. A hot air supply source 43 is connected to the passage 40b.

The dust collector 41 separates fine powder from the air extracted from the pulverizer 2 (hereinafter referred to as "mill exhaust"). In this embodiment, as the dust collector 41, a cyclone dust collector utilizing the suction action of the bleed fan 42 is employed. However, the dust collector 41 is not limited to a cyclone dust collector as long as it can separate fine powder from the mill exhaust.

A fine powder outlet of the dust collector 41 is connected to the second inlet 31b of the carrier 31 via a fine powder transport path 88 . Fine powder separated from the mill exhaust by the dust collector 41 is sent to the carrier 31 through the carrier path 88 .

In the passage 40 b connected to the outlet of the dust collector 41 , a passage 84 for sending the mill exhaust in the passage 40 b to the classifier 7 is connected downstream of the bleed fan 42 in the flow of the mill exhaust. This passage 84 is provided with a flow rate adjusting device 85 for adjusting the flow rate of the mill exhaust flowing to the classifier 7 . By changing the opening degree of the flow rate adjusting device 85, the flow rate of the mill exhaust gas flowing to the classifier 7 can be adjusted, and as a result, the flow rate of the mill exhaust gas returning to the crusher 2 can be adjusted. The flow rate adjusting device 85 may be any means for adjusting the flow rate of the mill exhaust flowing to the classifier 7, and may be, for example, at least one of a damper, a flow rate adjusting valve, and a fan.

The hot air supply source 43 may be, for example, a hot air generator that generates hot air at a desired temperature. The hot air supplied from the hot air supply source 43 to the gas circulation path 40 is sent to the hot air inlet 29a of the crusher 2 through the passage 40b together with the mill exhaust. However, the hot air supply source 43 is not limited to the hot air generating furnace. It may be used as a hot air supply source 43 .

[Powder production method using pulverization system 1]
Here, a method of operating the pulverization system 1 configured as described above and a method of producing powder using the pulverization system 1 will be described. In the crusher 2 , the inside of the crushing chamber 20 including the rotary table 22 and the crushing rollers 23 is preheated by hot air blown out from the hot air outlet 29 . Then, the rotary table 22 is rotationally driven by the mill motor 24, and the plurality of grinding rollers 23 whose peripheral surfaces are pressed against the grinding surface (upper surface) of the rotary table 22 are driven to rotate. The pulverized raw material is supplied through the supply port 26 onto the rotary table 22 rotating in this way. The crushed raw material is crushed between the rotary table 22 and the crushing rollers 23 . Coarse powder of the pulverized material overflows from the periphery of the rotary table 22 and is discharged out of the machine through the discharge port 28 . Further, the fine powder among the pulverized materials is discharged from the air bleed port 27 along with the rising air current.

The mill exhaust from the bleed port 27 of the crusher 2 flows into the dust collector 41 . In the dust collector 41 fines entrained in the mill exhaust are separated from the mill exhaust. The separated fine powder is sent to the second inlet 31b of the carrier 31 through the conveying path 88 and joins the flow of the pulverized material in the pulverized material circulation system 3 .

On the other hand, the mill exhaust from which fine powder has been separated by the dust collector 41 exits the dust collector 41, is sucked into the extraction fan 42, and is sent to the downstream passage 40b of the gas circulation system 4. Here, the opening degree of the flow rate adjusting device 85 is adjusted in order to balance the flow rate of the mill exhaust gas flowing into the passage 40b by the suction action of the bleed fan 42 and the flow rate of the mill exhaust gas returning to the crusher 2 . The hot air supplied from the hot air supply source 43 to the passage 40b flows into the crusher 2 together with the mill exhaust, and is blown out from the hot air outlet 29 into the mill.

The pulverized material discharged from the discharge port 28 of the crusher 2 is conveyed upward by the conveyer 31 and flows into the classifier 7 . The classifier 7 classifies the pulverized material and separates refined powder from the pulverized material. The pulverized material from which refined powder is separated by the classifier 7 is discharged from the classifier 7, sent to the feed port 26 of the pulverizer 2 through the passage 30c, and pulverized by the pulverizer 2 again. The refined powder separated from the pulverized material by the classifier 7 is discharged along with the gas from the exhaust port 73 of the classifier 7 and is conveyed to the collector 6 through the passage 64 by air flow. The collector 6 collects refined powder. This refined flour is recovered as a product and, for example, bagged. On the other hand, the gas separated from the refined powder by the collector 6 flows into the exhaust passage 65 and is released to the atmosphere.

[Fineness adjustment]
The fineness (degree of fineness of particles) of the refined flour collected as a product as described above is one of the important factors representing the quality of the refined flour. In the pulverization system 1 configured as described above, the fineness of the refined powder obtained can be changed by adjusting the extraction air flow rate F1. In order to verify that the fineness of refined powder can be adjusted by adjusting the extraction air flow rate F1, the following verification experiment was conducted.

In the verification experiment, a first experimental device simulating the crushing system 1 according to this embodiment and a second experimental device 101 (see FIG. 2) simulating a conventional crushing system were used.

The first experimental apparatus simulates the pulverization system 1 shown in FIG. 1, and detailed description thereof will be omitted. Experiments of Examples 1 to 4 were conducted using the first experimental apparatus. Table 1 shows the experimental conditions of Examples 1 to 4 and Comparative Example 1. In Examples 1 to 4, the classification air volume F2 was kept constant at 15 [m ³ /min]. In Example 1, the extraction air volume F1 is 0 [m ³ /min], in Example 2, the extraction air volume F1 is 3 [m ³ /min], and in Example 3, the extraction air volume F1 is 6 [m ³ /min]. 4, the bleed air volume F1 was set to 9 [m ³ /min]. The extraction air volume F1 is the exhaust air volume of the extraction fan 42, and the classifying air volume F2 is the exhaust air volume of the classifying fan 66. FIG.

FIG. 2 is a diagram showing the configuration of the second experimental apparatus 101. As shown in FIG. The second experimental apparatus 101 includes a vertical pulverizer 102, a collector 106 connected to an exhaust port 127 of the pulverizer 102, and a classifying fan 166 for sucking exhaust air from the pulverizer 102 to the collector 106. . The crusher 102 includes a housing 121 forming a crushing chamber 120, a rotary table 122 rotating around a vertical axis of rotation, and a plurality of crushing rollers 123 which are pressed against the rotary table 122 by pressure means (not shown) and are driven to rotate. , a mill motor 124 which is a rotational drive source of the rotary table 122, a reduction mechanism 125 which transmits the rotational power of the mill motor 124 to the rotary table 122, and a classifier 107 provided above the crushing rollers 123 in the housing 121. .

In the pulverizer 102, the pulverized raw material supplied onto the rotating rotary table 122 is pulverized between the rotary table 22 and the pulverizing roller 23 while being dried by hot air. Fine powder among the pulverized materials is carried to the classifier 107 by an air current blowing up from below, and the classifier 107 classifies the powder into refined powder and others. The refined powder is discharged from the exhaust port 127 on an air current and collected by the collector 106 . The fine powders classified by the classifier 107 other than the fine powders and the coarse powders overflowing from the periphery of the rotary table 122 are once discharged out of the machine and supplied to the crusher 102 again together with new crushed raw materials.

An experiment of Comparative Example 1 was conducted using the second experimental apparatus 101 configured as described above. In Comparative Example 1, the classification air volume F2 was kept constant at 15 [m ³ /min]. The classifying air volume F2 is the air volume of the classifying fan 166. FIG. In the second experimental apparatus 101, it is difficult to adjust only the extraction air volume because the extraction air volume (exhaust air volume) from the crusher 102 is directly affected by the classifying air volume F2.

In the experiments of Examples 1 to 4 and Comparative Example 1, the pulverized raw material was put into the mill of the experimental apparatus, and the refined powder was recovered. In order to specify the fineness of the recovered refined powder sample, a specific surface area test and a mesh sieve test were performed based on JIS R 5201 (physical test method for cement). In the specific surface area test, the Blaine specific surface area [cm ² /g] of the sample was measured using a specific surface area tester (Blaine air permeation measuring device). In the mesh sieve test, the sample is sieved using a test sieve with an opening of 45 μm, the residue on the sieve is weighed, and the residue [%] of the sample mesh sieve (hereinafter referred to as the content of particles with a particle size of 45 μm or more called "45 μR") was calculated.

FIG. 3 is a chart showing the correlation between the extraction air volume F1 from the pulverizer 2 and the fineness of the refined powder to be recovered. The vertical axis of this chart represents the specific surface area [cm ² /g], the horizontal axis represents 45 μR [%], and the fineness test results of the refined powders obtained in Examples 1 to 4 and Comparative Example 1 are plotted. ing. Common to Examples 1 to 4 and Comparative Example 1, at a constant bleed air volume F1, the specific surface area decreases as the value of 45 μR increases. Further, at a constant 45 μR, the specific surface area decreases as the extraction air volume F1 increases.

The value of the specific surface area is affected by fines in the refined flour. From the result that the specific surface area decreases as the extraction air flow rate F1 increases when 45 μR is a constant value, it is found that the fine powder content decreases as the extraction air flow rate F1 increases, resulting in a sharp fineness composition with a narrow distribution width. Recognize. In other words, it is possible to adjust the fineness (specific surface area) of the refined powder by adjusting the extraction air flow rate F1.

In addition, for Examples 1 to 4 and Comparative Example 1, the power unit consumption for producing refined flour was measured. As the electric power consumption rate, the electric power consumption rate of the mill motors 24 and 124 was measured. The power unit consumption of the mill motors 24, 124 accounts for the majority of the power unit consumption required for the production of refined flour. The measured electricity intensity is

FIG. 4 is a chart showing a characteristic curve of the power consumption rate of the pulverizer 2 with respect to the extraction air volume F1 from the pulverizer 2 for the production of refined flour in Examples 1 to 4 and Comparative Example 1. The vertical axis of this chart represents the ratio of the power unit consumption [kWh/t (DB)] of Examples 1 to 4 when the power consumption unit [kWh/t (DB)] of Comparative Example 1 is 100%. , the vertical axis represents the extraction air volume F1 [m ³ /min].

The electric power unit consumption of Examples 1 to 4 is lower than that of Comparative Example 1. In addition, when the extraction air volume F1 is less than about 4.5 m ³ /min, the power consumption rate gradually decreases as the extraction air volume F1 increases, and when the extraction air volume F1 is about 4.5 m ³ /min or more, the extraction air volume F1 does not increase. Accompanying this, the power consumption rate will gradually increase. In particular, when the extracted air flow rate F1 is in the range of about 2 to 6 m ³ /min, the power unit consumption is reduced by about 30% compared to the comparative example, and the power reduction effect is remarkable. It is presumed that this is because excessive pulverization is suppressed by extracting fine powder from the pulverizer 2 together with the extraction of air, and as a result, the electric power consumption rate is reduced. It is clear that there is a suitable range for the extraction air volume F1 from the viewpoint of reducing the power consumption rate.

From the results of the above verification experiments, it was verified that the fineness (specific surface area) of refined powder can be adjusted by adjusting the extraction air volume F1 from the pulverizer 2 . It was also verified that by adjusting the extraction air flow rate F1 from the crusher 2, it is possible to reduce the power consumption rate of the mill motor 24 by preventing excessive crushing.

In the operation method of the pulverization system 1 according to the present embodiment, the fineness of refined powder is adjusted using the verified principle. That is, the operating method of the pulverization system 1 according to the present embodiment includes the pulverizer 2 for pulverizing the pulverized raw material, the pulverized material circulation path 30 for moving the pulverized material from the discharge port 28 of the pulverizer 2 to the supply port 26, and the pulverization A classifier 7 that is provided in the material circulation path 30 and separates the pulverized material into fine powder that will be the product and coarse powder that is returned to the pulverizer 2, a collector 6 that collects the pulverized powder, Equipped with a connected extraction path 40a, an extraction fan 42 for extracting air from the crusher 2 to the extraction path 40a at a set extraction air volume, and a dust collector 41 for separating fine powder from the extraction air of the crusher 2 and sending it to the crushed material circulation path 30. A method of operating a pulverizing system, in which a correlation (see FIG. 3) is obtained between the amount of air extracted from the pulverizer 2 and the fineness of the refined powder to be collected, and the desired fineness is obtained based on the correlation. The extracted air volume is estimated, and the extracted air volume F1 is set as the set extracted air volume.

Further, in the powder manufacturing method using the pulverizing system 1 according to the present embodiment, the pulverized raw material is pulverized by the pulverizer 2, and air is extracted from the pulverizer 2 at a set extraction air flow rate to remove fine powder from the pulverized material. The fine powder is separated from the bleed air of the pulverizer 2 and conveyed to the classifier 7, and the rest of the pulverized material is conveyed from the pulverizer 2 to the classifier 7, where the classifier 7 pulverizes according to the set particle size. It includes classifying the material into fine powder and coarse powder, recovering the fine powder as a product, and returning the coarse powder from the classifier 7 to the crusher 2 for re-pulverization. Then, the correlation between the amount of air extracted from the crusher 2 and the fineness of the refined powder to be recovered (see FIG. 3) is obtained, and based on the correlation, the amount of air extracted to obtain the desired fineness is estimated, This bleed air volume is set as the set bleed air volume.

According to the powder manufacturing method described above, fine powder (powder) having an arbitrary fineness can be obtained by changing the set amount of extraction air. That is, by changing the fineness of the refined powder to be obtained, it is possible to obtain a powder product according to the purpose of use. As a result, it is possible to improve the quality of the powder product.

In addition, in the method of operating the pulverization system 1 and the method of manufacturing powder according to the present embodiment, a characteristic curve (see FIG. 4) of the power consumption rate of the pulverizer 2 with respect to the amount of extracted air is obtained, and a desired value is obtained based on the characteristic curve. Among the extraction air volume that can obtain the fineness, the extraction air volume that minimizes the electric power consumption is set as the set extraction air volume.

As a result, in addition to improving the quality of the refined powder (powder), it is possible to reduce the power unit consumption required for manufacturing the refined powder (powder).

Application examples of the method for producing powder according to the present embodiment will be described below.

If the crushed raw material is a cement raw material that contains a large amount of a mixture such as limestone, fine powder is likely to occur because limestone is softer than clinker. tends to be higher than In such a case, the value of the specific surface area of the refined powder can be lowered within the prescribed value by increasing the extraction air flow rate F1 while maintaining the 45 μR of the refined powder at a predetermined value. Thereby, the quality improvement of a cement raw material can be aimed at.

In addition, when the pulverized raw material is a cement raw material of a cement type (Portland cement, etc.) with a relatively small amount of mixture such as limestone, the value of the specific surface area of the refined powder tends to be lower than the value specified as a cement raw material. be. In such a case, it is possible to increase the value of the specific surface area of the refined powder to within the prescribed value by reducing the bleed air flow rate F1 while maintaining the 45 μR of the refined powder at a predetermined value. Thereby, the quality improvement of a cement raw material can be aimed at.

In the above, there is a range in the extraction air flow rate F1 that makes the value of the specific surface area of the refined powder within the specified value range. Therefore, by using the characteristic curve (see FIG. 4) of the power consumption rate with respect to the extraction air volume F1, and adopting the extraction air volume F1 that provides the desired fineness with the minimum power consumption rate, the raw material for cement In addition to improving the quality of the product, it is possible to reduce the power consumption rate.

1: Grinding system 2: Vertical pulverizer 3: Pulverized material circulation system 4: Gas circulation system 6: Collector 7: Classifier 20: Pulverization chamber 21: Housing 22: Rotary table 23: Pulverization roller 24: Mill motor 25: Reduction mechanism 26 : Supply port 27 : Exhaust port 28 : Discharge port 29 : Hot air outlet 29a : Hot air inlet 30 : Pulverized material circulation paths 30a, 30b, 30c : Passage 31 : Conveyor 31a : First inlet 31b : Second inlet 31c: Outlet 40: Gas circulation path 40a: Bleed path 40b: Passage 41: Dust collector 42: Exhaust fan 43: Hot air supply source 64: Passage 65: Exhaust path 66: Exhaust fan 71: Pulverized material inlet 72: Exhaust port 73: Exhaust Port 84 : Passage 85 : Flow rate adjusting device 88 : Conveying path 101 : Second experimental device 102 : Vertical pulverizer 106 : Collector 107 : Classifier 120 : Pulverization chamber 121 : Housing 122 : Rotary table 123 : Pulverization roller 124 : Mill motor 125 : Reduction mechanism 127 : Exhaust port 166 : Exhaust fan

Claims (4)

A vertical pulverizer for pulverizing the pulverized raw material,
a pulverized material circulation path through which the pulverized material moves from the discharge port of the vertical pulverizer to the supply port;
a classifier provided in the pulverized material circulation path to separate the pulverized material into fine powder to be a product and coarse powder to be returned to the vertical pulverizer;
a passage connected to the exhaust port of the classifier;
a collector for collecting the refined powder accompanying the gas discharged from the classifier to the passage ;
a classifying fan that exhausts air from the classifier to the passage at a predetermined classifying air volume;
a bleed passage connected to the top of the vertical pulverizer;
a bleed fan that bleeds air from the vertical pulverizer to the bleed path at a set bleed air volume;
A method of operating a pulverizing system comprising a dust collector that separates fine powder from the bleed air of the vertical pulverizer and sends it to the pulverized material circulation path,
Determine the correlation between the amount of air extracted from the vertical pulverizer and the fineness of the refined powder to be recovered, estimate the amount of air extracted to obtain the desired fineness based on the correlation, and set the amount of extracted air to the above With the set bleed air volume,
How to operate the comminution system. A characteristic curve of the electric power consumption rate of the vertical pulverizer with respect to the air bleed air volume is obtained, and based on the characteristic curve, the air bleed air volume with which the desired fineness is obtained and the electric power consumption rate is the minimum is the set bleed air volume. be the air volume,
A method of operating a comminution system according to claim 1. The pulverized raw material is pulverized with a vertical pulverizer, and air is extracted from the vertical pulverizer at a set extraction air flow rate, whereby fine powder among the pulverized materials is carried out on the air flow, and the fine powder is removed from the air extraction of the vertical pulverizer. The pulverized material is separated and conveyed to a classifier, the rest of the pulverized material is conveyed from the vertical pulverizer to the classifier, and the pulverized material is separated according to the set particle size by exhausting air from the classifier at a predetermined classification air volume. A method for producing powder, which includes classifying fine powder and coarse powder, recovering the fine powder as a product, and returning the coarse powder from the classifier to the vertical pulverizer for re-pulverization. ,
Determine the correlation between the amount of air extracted from the vertical pulverizer and the fineness of the refined powder to be recovered, estimate the amount of air extracted to obtain the desired fineness based on the correlation, and set the amount of extracted air to the above With the set bleed air volume,
Powder manufacturing method. A characteristic curve of the electric power consumption rate of the vertical pulverizer with respect to the air bleed air volume is obtained, and based on the characteristic curve, the air bleed air volume with which the desired fineness is obtained and the electric power consumption rate is the minimum is the set bleed air volume. be the air volume,
The method for producing powder according to claim 3.

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