JP2016159196A - Crushing method of coal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crushing method of coal capable of crushing coal to a target grain size by a simple method irrespective of a coal grain size before crushing.SOLUTION: In a certain brand of coal: coals having a plurality of different moisture contents are crushed in a crusher beforehand; parameters C/e, n in an equation are calculated on the basis of a crushing condition and a crushing result and using the equation exhibiting relationship between the crushing energy of coal and grain size distribution before and after crushing; and the relationships between the moisture content of coal and the parameters C/e, n are determined. When the certain brand of coal is crushed in the crusher: coal grain size (g) and moisture content (w) of coal before crushing are measured; the parameters C/e, n corresponding to the moisture content (w) on the basis of the relationship between the moisture content of coal and the parameters C/e, n are calculated; the load current value of the crusher from which target coal grain size (g) after crushing is obtained using the equation on the basis of the parameters C/e, n and the coal grain size (g) before crushing; and the current of the crusher is adjusted on the basis of the load current value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coal pulverization method, and relates to a pulverization method in which coal can be pulverized to a target particle size by changing the pulverization conditions by a simple method regardless of the coal particle size before pulverization. .

  Coke used in blast furnace operation has a role of a spacer for ensuring ventilation in the blast furnace, a role as a reducing material, a role as a heat source, and the like. Ensuring air permeability in the blast furnace is particularly important, and research for increasing the strength of coke has been conducted. The establishment of a coal blending method is important for increasing the strength of coke, but studies on coal crushing techniques are also being conducted (for example, Patent Documents 1 to 3). It seems that it has become quite clear whether it should be crushed. However, since the coal loaded in the yard causes particle size segregation at the top and bottom of the mountain due to the rolling of the coal when it is loaded on the mountain, when coal is cut out from this mountain and sequentially fed to the crusher, The particle size of the coal charged into the pulverizer changes every moment. Since pulverization is performed so that the pulverization particle size is constant in the pulverizer, it is difficult to stably pulverize the coal so as to obtain the target particle size when the particle size of the coal charged into the pulverizer changes.

Therefore, as a management method for pulverizing coal to a target particle size, the coal after pulverization is collected and dried, the sample after drying is sieved, and it is confirmed whether it is pulverized to the target particle size. However, since several hours are required for drying and sieving, the operation action in the case of deviating from the target pulverized particle size is greatly delayed. In order to solve such problems, for example, Patent Documents 4 to 7 propose the following methods.
(1) A method of performing particle size measurement using X-ray CT that can be measured in a shorter time because it requires a long time for drying and sieving (Patent Document 4)
(2) Method of collecting coal pulverized into fine powder for blowing blast furnace pulverized coal and measuring particle size with a laser diffraction particle size distribution analyzer (Patent Document 5)
(3) A method of measuring the particle size of the granular material conveyed by the conveying device from the displacement of the conveyed granular material surface (Patent Document 6)
(4) A method of taking a photograph of the granular material conveyed by the conveying device and measuring the particle size by image processing (Patent Document 7)

JP-A-8-259953 JP-A-9-279152 JP 2001-181650 A JP 2005-338011 A JP 2013-43998 A JP 2011-117806 A JP 2005-208024 A

Shinnosuke Miyawaki, Relationship between particle size distribution function of pulverized product and pulverization energy, Report of Akita University Mining Department, Underground Resource Development Laboratory, Akita University Mining Department, Underground Resource Research Facility, 1958, No. 19, pp. 50-58

However, the methods of Patent Documents 4 to 7 are obtained because (i) it is necessary to use an expensive measuring device, (ii) the influence of the dusting of the fine powder on the coarse particles, the influence of the aggregation of the fine powder, and the like. There are problems such as an error in the particle size distribution result. Further, the methods of Patent Documents 4 and 5 require a complicated operation of collecting a pulverized sample and measuring the particle size.
Accordingly, an object of the present invention is to solve the above-described problems of the prior art, and to provide a coal pulverization method capable of pulverizing coal to a target particle size by a simple method regardless of the particle size of the coal before pulverization. There is.

The features of the present invention for solving such problems are as follows.
[1] A method of pulverizing coal using an electric pulverizer, wherein for coal of a certain brand or hard glove index value, a plurality of coals having different moisture contents are pulverized in advance by a pulverizer, and the pulverization conditions Based on the pulverization result, the following formula (1) is used to calculate the parameter C / e, n, and the relationship between the moisture content of the coal and the parameter C / e, n is obtained. When pulverizing the index value coal with a pulverizer, the particle size (g ₀ ) and water content (w) of the coal before pulverization are measured, and the water content of the coal determined in advance and the parameter C / e, n Based on the relationship, the parameter C / e, n corresponding to the water content (w) is obtained, and the following equation (1) is used based on the parameter C / e, n and the particle size (g ₀ ) of the coal before pulverization. Pulverization to obtain the target pulverized coal particle size (g) Sought load current value, the coal grinding method, characterized by adjusting the current of the crusher on the basis of the load current value.
(AA ₀ ) * V / Q = {(C / e) / (n-1)} * {D ^(1-n) Γ ((1 + mn) / m) -D ₀ ^(1-n) Γ ( (1 + m ₀ -n) / m ₀ )}… (1)
However, A: Load current value of the pulverizer, and the average current value for 5 minutes when the pulverization amount is constant (A)
A ₀ : Load current value of pulverizer at no load (A)
C: grinding characteristic parameter (kg / m · s)
D: Rosin Ramler particle size characteristic number after grinding (m)
D ₀ : Rosin Ramler particle size characteristic number before grinding (m)
V: Voltage (V)
Q: Feeding speed of material into the grinder (kg / s)
e: Grinding efficiency (-)
m: Rosin Ramler even number after grinding (-)
m ₀ : Rosin Ramler even number before crushing (−)
n: power of Lewis formula
Γ: Gamma function

[2] A method of pulverizing coal using an electric pulverizer, wherein a plurality of coals having different hard glove index values are pulverized in advance with a pulverizer, and the pulverization conditions and Based on the pulverization result, the parameter C / e, n is calculated using the following equation (1), and the relationship between the hard glove index value and the water content of the coal and the parameter C / e, n is determined. When pulverizing coal with a glove index value using a pulverizer, the particle size (g ₀ ) and water content (w) of the coal before pulverization are measured. Based on the relationship with / e, n, a parameter C / e, n corresponding to the amount of water (w) is obtained. Based on this parameter C / e, n and the particle size (g ₀ ) of coal before pulverization, (1) Using the formula, target powder A method for pulverizing coal, comprising obtaining a load current value of a pulverizer capable of obtaining a grain size (g) of coal after pulverization, and adjusting the current of the pulverizer based on the load current value.
(AA ₀ ) * V / Q = {(C / e) / (n-1)} * {D ^(1-n) Γ ((1 + mn) / m) -D ₀ ^(1-n) Γ ( (1 + m ₀ -n) / m ₀ )}… (1)
However, A: Load current value of the pulverizer, and the average current value for 5 minutes when the pulverization amount is constant (A)
A ₀ : Load current value of pulverizer at no load (A)
C: grinding characteristic parameter (kg / m · s)
D: Rosin Ramler particle size characteristic number after grinding (m)
D ₀ : Rosin Ramler particle size characteristic number before grinding (m)
V: Voltage (V)
Q: Feeding speed of material into the grinder (kg / s)
e: Grinding efficiency (-)
m: Rosin Ramler even number after grinding (-)
m ₀ : Rosin Ramler even number before crushing (−)
n: power of Lewis formula
Γ: Gamma function [3] In the pulverization method of [1] or [2] above, when pulverizing coal with a pulverizer, the particle size (g ₀ ) and moisture content (w) of the coal before pulverization are set at regular intervals. And measuring the current of the pulverizer based on the load current value of the pulverizer determined at regular intervals based on the water content (w) and the coal particle size (g ₀ ). Crushing method.

  According to the present invention, using a formula representing the relationship between the coal pulverization energy and the particle size distribution before and after pulverization, and adjusting the current value of the pulverizer according to the particle size of the coal before pulverization, the particle size of the coal before pulverization Regardless, coal can be stably crushed to the target particle size. For this reason, it is possible to adjust the particle size so that the target pulverized particle size can be obtained easily and at low cost without taking a sample after pulverization and directly measuring the particle size or measuring the particle size using an expensive measuring instrument. .

The graph which shows the relationship between the hard glove index value and water content of coal, and the parameter C / e, n in the formula (1) used by the present invention The graph which shows transition of the grinding | pulverization coal particle size (average particle size) from the start of grinding | pulverization about the Example of this invention and Example 2 of Example 2.

When pulverizing coal with an electric pulverizer, if the pulverizer is operated with a constant load current, the energy associated with pulverization of the coal is pulverized. At that time, as described above, the particle size distribution of the coal that is input to the pulverizer changes.For example, when coal having a coarser particle size than normal is input, even if pulverization is performed with the same pulverization energy, The particle size distribution will be coarser than the target. On the contrary, when coal having a particle size finer than usual is introduced, the particle size distribution after pulverization becomes finer than the target.
From the mathematical expression shown in Non-Patent Document 1 (Expression (10) shown in “RR distribution” in the same document) as a mathematical expression representing the load current value of the pulverizer and the particle size change due to coal pulverization, the following expression (1) Can be derived.

(AA ₀ ) * V / Q = {(C / e) / (n-1)} * {D ^(1-n) Γ ((1 + mn) / m) -D ₀ ^(1-n) Γ ( (1 + m ₀ -n) / m ₀ )}… (1)
However, A: Load current value of the pulverizer, and the average current value for 5 minutes when the pulverization amount is constant (A)
A ₀ : Load current value of pulverizer at no load (A)
C: grinding characteristic parameter (kg / m · s)
D: Rosin Ramler particle size characteristic number after grinding (m)
D ₀ : Rosin Ramler particle size characteristic number before grinding (m)
V: Voltage (V)
Q: Feeding speed of material into the grinder (kg / s)
e: Grinding efficiency (-)
m: Rosin Ramler even number after grinding (-)
m ₀ : Rosin Ramler even number before crushing (−)
n: power of Lewis formula
Γ: Gamma function

Therefore, in the above equation (1), if the feed rate of the raw material, the load current of the pulverizer used for pulverization, and the particle size distribution of the coal before and after pulverization are determined, the parameter C / e, n can be obtained by calculation.
Here, the particle size characteristic number and equal number of Rosin Ramler are parameters included in the following Rosin Ramler distribution formula (expression expressing the particle size distribution of the granular material).
R ( _Dp ) = 100.exp (-( _Dp / D) ^m ) (2)
R (D _p ) represents the mass% of particles larger than D _p . The (2) becomes a formula Changing the following equation (3), sieving when put the left side of the following equation (3) with respect to D _p from the results, obtained even number than the slope is, the number of particle size properties than sections It is done. ε is the base of the natural logarithm.
_{log (log (100 / R (} D p)) = mlog (D p) m + log · log (ε) -mlog (D) ... (3)

In the above equation (1), the right side indicates the energy required to pulverize coal of a certain particle size to a certain particle size, and the left side indicates the power per unit mass of the pulverized material. And this equation (1) is the parameter of the particle size after grinding (= {(C / e) / (n-1)} * {D ^(1-n) Γ ((1 + mn) / m)}) And the particle size parameter before grinding (= {(C / e) / (n-1)} * {D ₀ ^(1-n) Γ ((1 + m ₀ -n) / m ₀ )}) (Energy difference) is proportional to the power used for grinding (= (AA ₀ ) * V / Q), and the proportionality constant is “(C / e) / (n−1)”.
That is, the above formula (1) means that the energy required per unit mass of the pulverized product is proportional to the parameter relating to the difference in particle size distribution before and after pulverization. When managing the particle size after pulverization, the above formula (1) shows that it is not possible to manage only by the load current value of the pulverizer spindle, and it is necessary to grasp the particle size before pulverization, the raw material charging speed, and the like.

The pulverization characteristics of coal depend on the hard glove index (an index used as an index of ease of pulverization; hereinafter referred to as “HGI”), but also depend on the moisture of the coal. It is also necessary to evaluate the effect of moisture. Therefore, for various brands of coal with different HGI values, those with different moisture contents were pulverized by a pulverizer, and based on the pulverization conditions and pulverization results, the parameter C / e, n was calculated using the above equation (1). I asked for it. As a result, it was found that the HGI value and water content of coal and the parameters C / e, n have a relationship as shown in FIGS. That is, it was found that the parameter C / e, n can be determined corresponding to the amount of water for coal having an arbitrary HGI value (coal of an arbitrary brand).
Here, since e is the grinding efficiency and is difficult to quantify, the C / e value is evaluated as a unique value for each brand or HGI value. The C / e value represents the ease of pulverization for each brand or HGI value, and the higher the C / e, the higher the energy and cost for pulverization. n is assumed to represent the mechanism of grinding.

Therefore, by using the above equation (1), the target particle size after pulverization (D, m in the above equation (1)) and the particle size before pulverization (D ₀ , m _{0 in the} above equation (1)) and Thus, the load current value A of the pulverizer can be obtained. For example, when cutting coal from a predetermined pile of coal and feeding it to a crusher and crushing it, by cutting out from the top and bottom of the coal pile, the coal to be fed to the crusher When the particle size distribution is changed, that is, when D ₀ or m _{0 in} the above formula (1) is changed, the load current value A of the pulverizer can be obtained so as to be a predetermined D or m as a target, Based on this, the current of the pulverizer is adjusted (that is, the pulverizer rotational speed is controlled using the load current value A as a target value), whereby the particle size distribution of the pulverized coal can be kept constant. Become.

Therefore, in the method of the present invention, coal is pulverized as follows using the above formula (1).
First, for a certain brand or HGI value coal to be pulverized, a plurality of coals having different moisture contents are pulverized in advance by a pulverizer, and based on the pulverization conditions and the pulverization result, the parameter C / e, n is calculated, and the relationship between the moisture content of the coal and the parameter C / e, n is obtained. Usually, since the HGI value of coal takes a value that is almost determined for each brand, the relationship between the moisture content of the coal and the parameters C / e, n may be obtained for the brand of coal to be crushed. However, even for the same brand, the HGI value may be slightly different for each lot, and a plurality of brands of coal may be mixed and pulverized. For this reason, a plurality of coals having different HGI values in the sense of a calibration curve are prepared, the relationship between the moisture content of the coals and the parameters C / e, n is obtained, and a certain HGI value to be crushed from now on is determined. For coal, the parameter C / e, n may be obtained based on the calibration curve. For example, ◯, □, and Δ surrounded by broken lines in FIGS. 1A and 1B indicate the relationship between the moisture content of a certain brand of coal (HGI value: 75) and the parameters C / e, n. In addition, about the determination of the HGI value of coal, it may sample for every lot of coal to arrive and may determine by measuring an HGI value. When mixing and pulverizing a plurality of brands of coal, the HGI value of the mixed coal may be measured and determined, or the coal obtained by weighting and averaging the HGI value of each coal to be mixed by the mixing ratio It is good also as an HGI value.

The parameters C / e, n are obtained from the above formula (1) by arranging the sieving data before and after pulverization using the Rosin-Lambler distribution formula. Specifically, for example, the parameter C / e, n can be obtained by the following methods (1) to (4).
(1) For coal whose moisture content and HGI value are known, a pulverization test is performed at two kinds of pulverizer rotation speeds, and the load current values A ₁ and A ₂ and the sieving particle size distribution at each pulverization are measured. Moreover, the raw material charging speeds Q ₁ and Q ₂ to the pulverizer are also measured.
(2) The uniform numbers m ₁ and m ₂ and the particle size characteristic numbers D ₁ and D ₂ are calculated from the sieved particle size distribution.
(3) For each of the left side and the right side of the above formula (1), a ratio is calculated between the two crusher rotation speeds as follows.
(Left side) {(A ₁ -A ₀ ) * V ₁ / Q ₁ } / {(A ₂ -A ₀ ) * V ₁ / Q ₂ }
(Right side) {D ₁ ^(1-n) Γ ((1 + m ₁ -n) / m ₁ ) -D ₀ ^(1-n) Γ ((1 + m ₀ -n) / m ₀ )}
/ {D ₂ ^(1-n) Γ ((1 + m ₂ -n) / m ₂ ) -D ₀ ^(1-n) Γ ((1 + m ₀ -n) / m ₀ )}
Then, n is calculated so that the value of the (left side) and the value of the (right side) that are known in the measurement are equal.
(4) Substituting the calculated n into the above equation (1), obtaining C / e for the two crusher rotation speeds, and setting the average value as the official C / e.
According to the analysis results conducted by the present inventors, C / e in (4) above is almost the same value as long as the HGI value (brand) and moisture content are constant even if the crusher rotational speed is changed.

As described above, the relationship between the moisture content of coal and the parameter C / e, n (for example, the relationship shown in FIGS. 1A and 1A) is obtained in advance and in actual operation. The coal of a certain brand or HGI value is pulverized by a pulverizer, and at that time, the particle size (g ₀ ) (particle size distribution) and the moisture content (w) of the coal before pulverization are measured and obtained in advance. Based on the relationship between the water content of coal and the parameter C / e, n, the parameter C / e, n corresponding to the water content (w) is obtained. For example, when pulverizing coal with an HGI value of 75, assuming that the relationship between the amount of water and parameters C / e, n shown in FIGS. When the amount (w) is 5% by mass, the parameter C / e corresponding to the moisture amount (w) is 600 kg / m · s, and the parameter n is 1.64.

Based on the parameter C / e, n thus determined and the particle size (g ₀ ) of the coal before pulverization, using the above equation (1), the target particle size (g) of the coal after pulverization (particle size) The load current value of the pulverizer from which the distribution is obtained is obtained. That is, in the above equation (1), the parameter C / e, n, D ₀ and m ₀ corresponding to the coal particle size (g ₀ ) before pulverization, and the target coal particle size (g) after pulverization Substituting D, m, etc. corresponding to, the load current value A of the pulverizer is obtained. This is the load current value of the pulverizer for obtaining the target coal particle size (g) after pulverization, and the pulverizer current is adjusted based on this value. That is, the rotational speed of the pulverizer spindle is controlled so that the load current value A becomes the target value. Usually, regardless of the particle size (g ₀ ) of the coal before pulverization, the calculation of the load current value A and the current of the pulverizer based on this are set so that the particle size (g) of the coal after pulverization becomes a constant target particle size. Adjustment (rotational speed control of the crusher spindle) is made.

Further, in the method of the present invention, as shown in FIGS. 1A and 1A, for a plurality of coals having different HGI values, a plurality of coals having different moisture contents are pulverized in advance by a pulverizer, and the pulverizing conditions and pulverization thereof are performed. Based on the results, the parameter C / e, n is calculated using the above equation (1), and the relationship between the HGI value and moisture content of the coal and the parameter C / e, n can be obtained. Accordingly, it is possible to appropriately cope with any HGI value coal to be pulverized. For example, even when the first brand of coal is crushed, the pulverization particle size can be easily controlled.
That is, in this case, when pulverizing coal with a hard glove index value with a pulverizer, the particle size (g ₀ ) and moisture content (w) of the coal before pulverization are measured, Based on the relationship between the hard glove index value and the moisture content and the parameter C / e, n, the parameter C / e, n corresponding to the moisture content (w) is obtained. Based on the particle size (g ₀ ), the above formula (1) is used to determine the load current value of the pulverizer from which the target pulverized coal particle size (g) can be obtained. The current is adjusted.

In carrying out the method of the present invention, the particle size (g ₀ ) and the moisture content (w) of the coal before pulverization are measured at regular intervals, and the moisture content (w) and the coal particle size (g ₀ ) are determined. It is preferable to adjust the current of the pulverizer based on the load current value of the pulverizer obtained at regular intervals.
When controlling the pulverization of coal to the target particle size using the above formula (1), in addition to adjusting the current of the pulverizer according to the method of the present invention, if there is a surplus in production volume, The raw material charging speed may be adjusted. If the above formula (1) is used, it is possible to grasp how much the raw material charging speed should be adjusted quantitatively.

[Example 1]
A pulverization test was performed under the following conditions using five brands of coal having an HGI value of 55 to 90 described in JIS M8801, and the relationship between the moisture content of the coal and the parameters C / e, n was determined. The pulverizer was an impact type cage mill (cage diameter 830 mm, electric motor output maximum 37 kW, pulverization capacity maximum 10 t / h), and the raw material charging speed to the pulverizer was 5 t / h on a dry basis. The pulverization speed was 500 rpm, 600 rpm, 700 rpm, and 800 rpm. The coal moisture content is 3 levels of 5%, 8% and 12% by mass, and a pulverization test is conducted with 5 brands of coal as each moisture content. Based on the pulverization conditions and pulverization results, Parameter C / e, n was calculated. The specific calculation method is as described above. C / e and n were calculated using a total of four combinations of 500 rpm and 600 rpm, 600 rpm and 700 rpm, 700 and 800 rpm, and 500 rpm and 800 rpm. There was almost no influence of the grinding rotation speed on C / e and n. The relationship between the calculated parameter C / e, n and the HGI value and water content of coal is shown in FIG.

Using the same pulverizer as described above, coal having an HGI value of 70 and a water content of 8% by mass was pulverized. From the relationship of FIG. 1 obtained in advance, the parameter C / e was determined to be 1300 kg / m · s, and the parameter n was determined to be 1.35. D ₀ before pulverization was 5.85 mm, and m ₀ was 0.71. When the target D after grinding is 0.78 mm and m is 1.00, the load current value difference between the grinding machine spindle at the time of grinding and no load is 14 in order to obtain the target grinding particle size from the above formula (1). .7A is calculated. When actually measured, it was experimentally found that the target particle size was 14.9 A, and it was found that the target pulverized particle size can be easily controlled using the above equation (1).

[Example 2]
In order to confirm the effectiveness of the method of the present invention using the above formula (1), a two-day grinding test was conducted in actual operation. As the pulverizer, an impact type cage mill (cage diameter 830 mm, electric motor output maximum 37 kW, pulverization capacity maximum 10 t / h) was used. The cutting out of the weighing belt feeder was adjusted so as to be 5 t / h on a dry base, and the raw material charging speed into the pulverizer was controlled. Coal brand with HGI of 75 was used for the coal. The test was conducted as follows. In addition, the relationship between the HGI value and water content of the coal and the parameters C / e, n shown in FIGS. 1A and 1B is obtained in advance.
(1) Measure the particle size and water content of the coal to be crushed before grinding.
(2) The parameter C / e, n is determined from the relationship shown in FIG.
(3) The target coal pulverization particle size, the coal pre-pulverization particle size, and the parameter C / e, n are substituted into the above equation (1) to obtain the target coal pulverization particle size load current value A (target Value).
(4) Set the grinding rotation speed so that the load current value A becomes the target value.
(5) Measure the particle size and water content before pulverization of coal every 4 hours, repeat the above (1) to (4), review the parameters C / e, n and the load current value A (target value), Based on this, the grinding rotation speed is set.

  In contrast to the examples of the present invention in which the above (1) to (5) are performed, a case in which the number of rotations is fixed and then pulverized after the determination of the number of rotations is taken as a comparative example. In order to confirm the effect of the present invention, pulverized charcoal was sampled every 4 hours in the present invention example and the comparative example, and the particle size was measured. FIG. 2 shows the transition of the pulverized coal particle size (average particle size) from the start of pulverization for the inventive example and the comparative example. According to this, in the examples of the present invention and the comparative examples, the average particle size of the pulverized charcoal was 0.64 mm immediately after the start of pulverization, and the pulverized particle size remained almost unchanged until 4 hours from the start of pulverization. However, after that, in the case of the comparative example, the variation in the average particle diameter started to be noticeable. On the other hand, in the present invention example, the raw material particle size and raw material moisture are measured every 4 hours, the parameters C / e, n and the load current value A (target value) are reviewed, and the target load current value A is satisfied. Therefore, the average particle size variation was effectively suppressed. This confirmed the effectiveness of the present invention.

Claims (3)

A method of pulverizing coal using an electric pulverizer,
For coal of a certain brand or hard glove index value, a plurality of coals having different moisture contents are pulverized in advance by a pulverizer, and based on the pulverization conditions and pulverization results, parameters C / e, n are calculated using the following equation (1). And calculate the relationship between the moisture content of the coal and the parameter C / e, n,
When pulverizing coal of a certain brand or hard glove index value with a pulverizer, the particle size (g ₀ ) and moisture content (w) of the coal before pulverization are measured, and the moisture content and parameters of the coal determined in advance are measured. Based on the relationship with C / e, n, a parameter C / e, n corresponding to the water content (w) is obtained, and based on this parameter C / e, n and the particle size (g ₀ ) of the coal before pulverization, Using the following equation (1), the load current value of a pulverizer capable of obtaining the target particle size (g) of coal after pulverization is obtained, and the current of the pulverizer is adjusted based on the load current value. To pulverize coal.
(AA ₀ ) * V / Q = {(C / e) / (n-1)} * {D ^(1-n) Γ ((1 + mn) / m) -D ₀ ^(1-n) Γ ( (1 + m ₀ -n) / m ₀ )}… (1)
However, A: Load current value of the pulverizer, and the average current value for 5 minutes when the pulverization amount is constant (A)
A ₀ : Load current value of pulverizer at no load (A)
C: grinding characteristic parameter (kg / m · s)
D: Rosin Ramler particle size characteristic number after grinding (m)
D ₀ : Rosin Ramler particle size characteristic number before grinding (m)
V: Voltage (V)
Q: Feeding speed of material into the grinder (kg / s)
e: Grinding efficiency (-)
m: Rosin Ramler even number after grinding (-)
m ₀ : Rosin Ramler even number before crushing (−)
n: power of Lewis formula
Γ: Gamma function A method of pulverizing coal using an electric pulverizer,
For coals with different hard glove index values, coals with different moisture contents are pulverized in advance with a pulverizer, and parameters C / e, n are calculated using the following equation (1) based on the pulverization conditions and pulverization results. Calculate and determine the relationship between the hard glove index value and moisture content of coal and the parameters C / e, n,
When pulverizing coal with a certain hard glove index value with a pulverizer, the particle size (g ₀ ) and water content (w) of the coal before pulverization are measured, and the hard glove index value and water content of the coal determined in advance are measured. And parameter C / e, n is determined based on the relationship between the amount of water (w) and the parameter C / e, n and the coal particle size (g ₀ ) before pulverization. Based on the following equation (1), the load current value of the pulverizer for obtaining the target grain size (g) of the coal after pulverization is obtained, and the current of the pulverizer is adjusted based on the load current value. A method for pulverizing coal.
(AA ₀ ) * V / Q = {(C / e) / (n-1)} * {D ^(1-n) Γ ((1 + mn) / m) -D ₀ ^(1-n) Γ ( (1 + m ₀ -n) / m ₀ )}… (1)
However, A: Load current value of the pulverizer, and the average current value for 5 minutes when the pulverization amount is constant (A)
A ₀ : Load current value of pulverizer at no load (A)
C: grinding characteristic parameter (kg / m · s)
D: Rosin Ramler particle size characteristic number after grinding (m)
D ₀ : Rosin Ramler particle size characteristic number before grinding (m)
V: Voltage (V)
Q: Feeding speed of material into the grinder (kg / s)
e: Grinding efficiency (-)
m: Rosin Ramler even number after grinding (-)
m ₀ : Rosin Ramler even number before crushing (−)
n: power of Lewis formula
Γ: Gamma function When pulverizing coal with a pulverizer, the particle size (g ₀ ) and moisture content (w) of the coal before pulverization are measured at regular intervals, and the moisture content (w) and coal particle size (g ₀ ) The coal pulverization method according to claim 1, wherein the current of the pulverizer is adjusted based on a load current value of the pulverizer obtained at regular intervals.

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