JP2016159196A - Crushing method of coal - Google Patents
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本発明は、石炭の粉砕方法に関するもので、粉砕前の石炭の粒度に関わりなく、粉砕条件を簡便な方法で変更して、石炭を目標の粒度に粉砕できるようにした粉砕方法に関するものである。 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. .
高炉操業で使用されるコークスには、高炉内の通気を確保するためのスペーサーの役割、還元材としての役割、熱源としての役割などがある。高炉内の通気性の確保は特に重要であり、そのためにコークスを高強度化するための研究が従来から行われている。コークスの高強度化には石炭配合法の確立が重要であるが、石炭の粉砕技術の検討も行われており(例えば、特許文献1〜3)、これらの検討により、どの銘柄の石炭をどの程度粉砕すべきかについて、かなり明確になってきていると考えられる。しかし、ヤードに積まれた石炭は、山に積み付けする時に石炭の転動によって山の頂部と裾野部とで粒度偏析が生じるため、この山から石炭を切り出して粉砕機へ順次送給すると、粉砕機に投入される石炭の粒度が刻々と変化してしまう。粉砕機では粉砕粒度が一定となるように粉砕が行われるので、粉砕機に投入される石炭の粒度が変化すると、目標の粒度となるように安定して石炭を粉砕することは困難となる。 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.
そこで、石炭を目標の粒度に粉砕するための管理方法として、粉砕後の石炭を採取・乾燥し、乾燥後試料を篩い分けし、目標粒度に粉砕されているかどうかの確認が行われている。しかし、乾燥と篩い分けには数時間を要するため、目標の粉砕粒度から外れた場合の操業アクションが大きく遅れることになる。このような問題を解決するため、例えば、特許文献4〜7には以下のような方法が提案されている。
(1)乾燥と篩い分けに長時間必要であるため、より短時間で測定可能なX線CTを用いて粒度測定を行う方法(特許文献4)
(2)高炉微粉炭吹き込み用として微粉に粉砕された石炭を採取し、レーザ回折式粒度分布測定器により粒度を測定する方法(特許文献5)
(3)搬送装置によって搬送される粉粒体の粒度を、搬送される粉粒体表面の変位から測定する方法(特許文献6)
(4)搬送装置によって搬送される粉粒体を写真撮影し、画像処理より粒度を測定する方法(特許文献7)
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)
しかし、特許文献4〜7の方法には、(i)高価な測定機器を用いる必要がある、(ii)粗大粒子への微粉のまぶりつきの影響や微粉どうしの凝集の影響などにより、得られる粒度分布結果に誤差を伴う、などの問題がある。また、特許文献4,5の方法は、粉砕後の試料を採取して粒度測定するという煩雑な作業が必要である。
したがって本発明の目的は、以上のような従来技術の課題を解決し、粉砕前の石炭の粒度に関わりなく、簡便な手法で石炭を目標粒度に粉砕することができる石炭の粉砕方法を提供することにある。
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.
このような課題を解決するための本発明の特徴は以下の通りである。
[1]電動式の粉砕機を用いて石炭を粉砕する方法であって、或る銘柄またはハードグローブ指数値の石炭について、予め複数の異なる水分量の石炭を粉砕機で粉砕し、その粉砕条件および粉砕結果に基づき、下記(1)式を用いてパラメーターC/e,nを算出し、石炭の水分量とパラメーターC/e,nとの関係を求めておき、前記或る銘柄またはハードグローブ指数値の石炭を粉砕機で粉砕するに当たり、粉砕前の石炭の粒度(g0)と水分量(w)を測定し、予め求められている石炭の水分量とパラメーターC/e,nとの関係に基づき、水分量(w)に対応するパラメーターC/e,nを求め、このパラメーターC/e,nと、粉砕前の石炭の粒度(g0)に基づき、下記(1)式を用いて、目標とする粉砕後の石炭の粒度(g)が得られる粉砕機の負荷電流値を求め、該負荷電流値に基づき粉砕機の電流を調整することを特徴とする石炭の粉砕方法。
(A-A0)*V/Q={(C/e)/(n-1)}*{D(1-n)Γ((1+m-n)/m)-D0 (1-n)Γ((1+m0-n)/m0)} …(1)
ただし A:粉砕機の負荷電流値であって、粉砕量一定時の5分間平均電流値(A)
A0:無負荷時の粉砕機の負荷電流値(A)
C:粉砕特性パラメーター(kg/m・s)
D:粉砕後のロージンラムラー粒度特性数(m)
D0:粉砕前のロージンラムラー粒度特性数(m)
V:電圧(V)
Q:粉砕機への原料投入速度(kg/s)
e:粉砕効率(−)
m:粉砕後のロージンラムラー均等数(−)
m0:粉砕前のロージンラムラー均等数(−)
n:ルイス式のべき数
Γ:ガンマ関数
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]電動式の粉砕機を用いて石炭を粉砕する方法であって、複数の異なるハードグローブ指数値の石炭について、予め複数の異なる水分量の石炭を粉砕機で粉砕し、その粉砕条件および粉砕結果に基づき、下記(1)式を用いてパラメーターC/e,nを算出し、石炭のハードグローブ指数値および水分量とパラメーターC/e,nとの関係を求めておき、或るハードグローブ指数値の石炭を粉砕機で粉砕するに当たり、粉砕前の石炭の粒度(g0)と水分量(w)を測定し、予め求められている石炭のハードグローブ指数値および水分量とパラメーターC/e,nとの関係に基づき、水分量(w)に対応するパラメーターC/e,nを求め、このパラメーターC/e,nと、粉砕前の石炭の粒度(g0)に基づき、下記(1)式を用いて、目標とする粉砕後の石炭の粒度(g)が得られる粉砕機の負荷電流値を求め、該負荷電流値に基づき粉砕機の電流を調整することを特徴とする石炭の粉砕方法。
(A-A0)*V/Q={(C/e)/(n-1)}*{D(1-n)Γ((1+m-n)/m)-D0 (1-n)Γ((1+m0-n)/m0)} …(1)
ただし A:粉砕機の負荷電流値であって、粉砕量一定時の5分間平均電流値(A)
A0:無負荷時の粉砕機の負荷電流値(A)
C:粉砕特性パラメーター(kg/m・s)
D:粉砕後のロージンラムラー粒度特性数(m)
D0:粉砕前のロージンラムラー粒度特性数(m)
V:電圧(V)
Q:粉砕機への原料投入速度(kg/s)
e:粉砕効率(−)
m:粉砕後のロージンラムラー均等数(−)
m0:粉砕前のロージンラムラー均等数(−)
n:ルイス式のべき数
Γ:ガンマ関数
[3]上記[1]または[2]の粉砕方法において、石炭を粉砕機で粉砕するに当たり、一定時間おきに粉砕前の石炭の粒度(g0)と水分量(w)を測定し、この水分量(w)と石炭の粒度(g0)をもとに一定時間おきに求められる粉砕機の負荷電流値に基づき、粉砕機の電流を調整することを特徴とする石炭の粉砕方法。
[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.
本発明によれば、石炭の粉砕エネルギーと粉砕前後の粒度分布の関係を表す式を用い、粉砕前の石炭の粒度に応じて粉砕機の電流値を調整することにより、粉砕前の石炭の粒度に関わりなく、石炭を目標とする粒度に安定的に粉砕することができる。このため、粉砕後の試料を採取して直接粒度測定したり、高価な測定機器を用いて粒度測定したりすることなく、簡便かつ低コストに目標粉砕粒度となるような粒度調整が可能となる。 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. .
電動式の粉砕機で石炭を粉砕する際に、負荷電流を一定にして粉砕機を運転すると、石炭の粉砕に係るエネルギーを一定にして粉砕することになる。その際に、前述のように粉砕機に投入される石炭の粒度分布が変化し、例えば、普通よりも粗い粒度の石炭が投入されると、同じ粉砕エネルギーで粉砕をしても、粉砕後の粒度分布は目標よりも粗くなってしまう。逆に、普通よりも細かい粒度の石炭が投入されると、粉砕後の粒度分布は目標よりも細かくなってしまう。
粉砕機の負荷電流値と石炭の粉砕による粒度変化を表す数式として非特許文献1に示される数式(同文献の「R−R分布」に示される(10)式)から、下記(1)式を導出することができる。
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.
(A-A0)*V/Q={(C/e)/(n-1)}*{D(1-n)Γ((1+m-n)/m)-D0 (1-n)Γ((1+m0-n)/m0)} …(1)
ただし A:粉砕機の負荷電流値であって、粉砕量一定時の5分間平均電流値(A)
A0:無負荷時の粉砕機の負荷電流値(A)
C:粉砕特性パラメーター(kg/m・s)
D:粉砕後のロージンラムラー粒度特性数(m)
D0:粉砕前のロージンラムラー粒度特性数(m)
V:電圧(V)
Q:粉砕機への原料投入速度(kg/s)
e:粉砕効率(−)
m:粉砕後のロージンラムラー均等数(−)
m0:粉砕前のロージンラムラー均等数(−)
n:ルイス式のべき数
Γ:ガンマ関数
(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
したがって、上記(1)式において、原料の投入速度、粉砕に用いた粉砕機の負荷電流、粉砕前後の石炭の粒度分布が決まると、パラメーターC/e,nは、計算により求めることができる。
ここで、ロージンラムラーの粒度特性数や均等数は、下記(2)式のロージンラムラー分布式(粉粒物の粒度分布を表す式)に含まれるパラメーターである。
R(Dp)=100・exp(−(Dp/D)m) …(2)
R(Dp)はDpよりも大きい粒子の質量%を示す。この(2)式を変更すると下記(3)式となるが、篩い分け結果よりDpに対して下記(3)式の左辺をプットすると、傾きより均等数が、切片より粒度特性数が得られる。εは自然対数の底である。
log(log(100/R(Dp))=mlog(Dp)m+log・log(ε)−mlog(D) …(3)
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)
上記(1)式において、右辺は、或る粒度の石炭を或る粒度に粉砕するときに要するエネルギーを示し、左辺は、その時にかかる粉砕物単位質量当たり動力を示している。そして、この(1)式は、粉砕後の粒度のパラメーター(={(C/e)/(n-1)}*{D(1-n)Γ((1+m-n)/m)})と粉砕前の粒度のパラメーター(={(C/e)/(n-1)}*{D0 (1-n)Γ((1+m0-n)/m0)})の差し引き分(エネルギー差)が、粉砕に使う動力(=(A-A0)*V/Q)に比例することを示しており、その比例定数が「(C/e)/(n-1)」である。
つまり、上記(1)式は、粉砕物単位質量当たりに必要なエネルギーは、粉砕前後の粒度分布差に関するパラメーターに比例することを意味する。粉砕後粒度の管理をする場合、粉砕機主軸の負荷電流値のみでは管理できず、粉砕前の粒度や原料投入速度なども把握する必要があることを上記(1)式は示している。
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.
石炭の粉砕特性はハードグローブ指数(粉砕のし易さの指標として用いられる指数。以下「HGI」という)に依存するが、さらに石炭水分にも依存するので、パラメーターC/e,nに及ぼす石炭水分の影響も評価する必要がある。そこで、HGI値が異なる様々な銘柄の石炭について、水分量を変えたものを粉砕機で粉砕し、その粉砕条件および粉砕結果に基づき、上記(1)式を用いてパラメーターC/e,nを求めてみた。その結果、石炭のHGI値および水分量とパラメーターC/e,nには、図1(ア)、(イ)に示すような関係があることが判った。すなわち、任意のHGI値の石炭(任意の銘柄の石炭)について、水分量に対応してパラメーターC/e,nを決めることができることが判った。
ここで、eは粉砕効率であり定量化は困難なため、C/e値を銘柄またはHGI値ごとの固有な値として評価する。C/e値は銘柄またはHGI値ごとの粉砕のし易さを表し、C/eが高いほど粉砕にかかるエネルギーやコストが高いことを示す。nは粉砕のメカニズムを表すとされる。
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.
したがって、上記(1)式を用いることにより、粉砕前の粒度(上記(1)式のD0、m0)に応じて、粉砕後の目標粒度(上記(1)式のD、m)となるような粉砕機の負荷電流値Aを求めることができる。例えば、所定の石炭の山から順次石炭を切り出して粉砕機へ送給し、粉砕を行っている際に、石炭の山の頂部や裾野部から切り出すことで、粉砕機に送給される石炭の粒度分布が変化したとき、すなわち上記(1)式のD0やm0が変化したときに、目標とする所定のDやmとなるように粉砕機の負荷電流値Aを求めることができ、これに基づいて粉砕機の電流を調整する(すなわち、その負荷電流値Aを目標値として粉砕機回転数を制御する)ことにより、粉砕後の石炭の粒度分布を一定に維持することが可能となる。 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.
このため本発明法では、上記(1)式を用い、以下のようにして石炭の粉砕を行う。
まず、粉砕しようとする或る銘柄またはHGI値の石炭について、予め複数の異なる水分量の石炭を粉砕機で粉砕し、その粉砕条件および粉砕結果に基づき、上記(1)式を用いてパラメーターC/e,nを算出し、石炭の水分量とパラメーターC/e,nとの関係を求めておく。通常、石炭のHGI値は銘柄毎にほぼ決まった数値をとるので、粉砕しようとする銘柄の石炭について、石炭の水分量とパラメーターC/e,nとの関係を求めておけばよい。ただし、同じ銘柄でもロット毎に少しHGI値が異なることがあり、また、複数の銘柄の石炭を混合して粉砕することもある。このため、検量線のような意味合いでHGI値の異なる複数の石炭を準備し、石炭の水分量とパラメーターC/e,nとの関係を求めておき、これから粉砕しようとする或るHGI値の石炭について、上記検量線に基づきパラメーターC/e,nを求めておいてもよい。例えば、図1(ア)、(イ)の破線で囲った○、□、△が或る銘柄の石炭(HGI値:75)の水分量とパラメーターC/e,nとの関係を示す。なお、石炭のHGI値の決定については、入荷する石炭のロット毎にサンプリングし、HGI値を測定して決めてもよい。また、複数の銘柄の石炭を混合して粉砕するときには、混合した石炭のHGI値を測定して決めてもよいし、混合する各石炭のHGI値を混合比率で加重平均した値を混合した石炭のHGI値としてもよい。
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.
パラメーターC/e,nは、粉砕前後の篩い分けデータをロージンラムラー分布式で整理し、上記(1)式より求める。具体的には、例えば、下記(1)〜(4)のような手法でパラメーターC/e,nを求めることができる。
(1)水分量とHGI値が既知の石炭について、2種類の粉砕機回転数で粉砕試験を行い、各々の粉砕時の負荷電流値A1,A2および篩い分け粒度分布を測定する。また、粉砕機への原料投入速度Q1,Q2も測定する。
(2)篩い分け粒度分布より、均等数m1,m2および粒度特性数D1,D2を算出する。
(3)上記(1)式の左辺および右辺の各々について、以下のように2つの粉砕機回転数の間で比をとる。
(左辺){(A1-A0)*V1/Q1}/{(A2-A0)*V1/Q2}
(右辺){D1 (1-n)Γ((1+m1-n)/m1)-D0 (1-n)Γ((1+m0-n)/m0)}
/{D2 (1-n)Γ((1+m2-n)/m2)-D0 (1-n)Γ((1+m0-n)/m0)}
そして、測定で既知となる(左辺)の値と(右辺)の値が等しくなるnを算出する。
(4)算出したnを上記(1)式に代入し、2つの粉砕機回転数についてC/eを求め、その平均値を正式なC/eとする。
本発明者らの行った解析結果では、上記(4)のC/eは粉砕機回転数を変えてもHGI値(銘柄)、水分量が一定であれば、ほぼ同じ値となる。
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.
以上のように、予め石炭の水分量とパラメーターC/e,nとの関係(例えば、図1(ア)、(イ)に示されるような関係)を求めておいた上で、実操業において、前記或る銘柄またはHGI値の石炭を粉砕機で粉砕するが、その際、粉砕前の石炭の粒度(g0)(粒度分布)と水分量(w)を測定し、予め求められている石炭の水分量とパラメーターC/e,nとの関係に基づき、水分量(w)に対応するパラメーターC/e,nを求める。例えば、HGI値が75の石炭を粉砕するに当たり、予め図1(ア)、(イ)に示される水分量とパラメーターC/e,nとの関係が求められているとすると、測定された水分量(w)が5質量%の場合、この水分量(w)に対応するパラメーターC/eは600kg/m・s、パラメーターnは1.64となる。 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.
このようにして求めたパラメーターC/e,nと、粉砕前の石炭の粒度(g0)に基づき、上記(1)式を用いて、目標とする粉砕後の石炭の粒度(g)(粒度分布)が得られる粉砕機の負荷電流値を求める。すなわち、上記(1)式に、上記パラメーターC/e,nと、粉砕前の石炭の粒度(g0)に対応するD0、m0と、目標とする粉砕後の石炭の粒度(g)に対応するD、mなどを代入し、粉砕機の負荷電流値Aを求める。これが、目標とする粉砕後の石炭の粒度(g)が得られる粉砕機の負荷電流値であり、これに基づき粉砕機の電流を調整する。すなわち、負荷電流値Aが目標値となるように粉砕機主軸の回転数制御を行う。通常、粉砕前の石炭の粒度(g0)に関わりなく、粉砕後の石炭の粒度(g)が一定の目標粒度となるように、負荷電流値Aの算出とこれに基づく粉砕機の電流の調整(破砕機主軸の回転数制御)がなされる。 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.
また、本発明法では、図1(ア)、(イ)に示すように、複数の異なるHGI値の石炭について、予め複数の異なる水分量の石炭を粉砕機で粉砕し、その粉砕条件および粉砕結果に基づき、上記(1)式を用いてパラメーターC/e,nを算出し、石炭のHGI値および水分量とパラメーターC/e,nとの関係を求めておくことができる。これにより、どのようなHGI値の石炭を粉砕対象とする場合でも適切に対応でき、例えば、初めての銘柄の石炭を破砕する場合でも、簡便に粉砕粒度を制御することができる。
すなわち、この場合には、或るハードグローブ指数値の石炭を粉砕機で粉砕するに当たり、粉砕前の石炭の粒度(g0)と水分量(w)を測定し、予め求められている石炭のハードグローブ指数値および水分量とパラメーターC/e,nとの関係に基づき、水分量(w)に対応するパラメーターC/e,nを求め、このパラメーターC/e,nと、粉砕前の石炭の粒度(g0)に基づき、上記(1)式を用いて、目標とする粉砕後の石炭の粒度(g)が得られる粉砕機の負荷電流値を求め、この負荷電流値に基づき粉砕機の電流を調整するものである。
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.
また、本発明法を実施するに際しては、一定時間おきに粉砕前の石炭の粒度(g0)と水分量(w)を測定し、この水分量(w)と石炭の粒度(g0)をもとに一定時間おきに求められる粉砕機の負荷電流値に基づき、粉砕機の電流を調整することが好ましい。
なお、上記(1)式を利用して石炭を目標とする粒度に粉砕する制御を行う場合、本発明法により粉砕機の電流を調整する以外に、生産量に余裕があれば、粉砕機への原料投入速度の調整を行ってもよい。上記(1)式を用いれば、定量的にどの程度、原料投入速度を調整すればよいかを把握することができる。
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.
[実施例1]
JIS M8801に記載されているHGI値が55〜90の石炭を5銘柄用いて、以下のような条件で粉砕試験を行い、石炭の水分量とパラメーターC/e,nとの関係を求めた。粉砕機は衝撃式のケージミル(ケージ直径830mm、電動機出力最大37kW、粉砕能力最大10t/h)を用い、粉砕機への原料投入速度はドライベースで5t/hとした。粉砕回転数は500rpm、600rpm、700rpm、800rpmとした。石炭水分量は5質量%、8質量%、12質量%の3水準とし、5銘柄の石炭を各水分量にして粉砕試験を行い、その粉砕条件および粉砕結果に基づき、上記(1)式を用いてパラメーターC/e,nを算出した。具体的な算出方法はさきに述べた通りである。500rpmと600rpm、600rpmと700rpm、700と800rpmおよび500rpmと800rpmの計4つの組合せでC/eとnの算出を行った。C/eとnに対して粉砕回転数の影響はほとんどなかった。算出されたパラメーターC/e,nと石炭のHGI値および水分量との関係を図1に示す。
[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.
上記と同じ粉砕機を用いて、HGI値が70、水分量が8質量%の石炭の粉砕を実施した。予め得られている図1の関係から、パラメーターC/eを1300kg/m・s、パラメーターnを1.35と決定した。粉砕前のD0は5.85mm、m0は0.71であった。目標となる粉砕後のDを0.78mm、mを1.00とすると、上記(1)式より目標の粉砕粒度となるには、粉砕時と無負荷時の粉砕機主軸の負荷電流値差が14.7Aであると計算される。実測すると14.9Aで目標粒度となることが実験的に判明し、上記(1)式を用いて簡便に目標粉砕粒度の制御が可能であることが判った。 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).
[実施例2]
上記(1)式を用いる本発明法の有効性を確認するため、実操業にて2日間の粉砕試験を行った。粉砕機は衝撃式のケージミル(ケージ直径830mm、電動機出力最大37kW、粉砕能力最大10t/h)を用いた。ドライベースで5t/hとなるように、秤量ベルトフィーダーの切出し調整を行い、粉砕機への原料投入速度を制御した。石炭にはHGIが75の石炭銘柄を用いた。試験は以下のようにして行った。なお、図1(ア)、(イ)に示す石炭のHGI値および水分量とパラメーターC/e,nとの関係は予め求められている。
(1)粉砕対象の石炭の粉砕前粒度および水分量を測定する。
(2)図1の関係から、パラメーターC/e,nを決定する。
(3)目標の石炭粉砕粒度、石炭の粉砕前粒度、パラメーターC/e,nを上記(1)式に代入し、目標の石炭粉砕粒度とするための粉砕機主軸の負荷電流値A(目標値)を算出する。
(4)負荷電流値Aが目標値となるように粉砕回転数を設定する。
(5)4時間おきに石炭の粉砕前粒度および水分量を測定して、上記(1)〜(4)を繰り返し、パラメーターC/e,nと負荷電流値A(目標値)の見直しと、これに基づく粉砕回転数の設定を行う。
[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.
上記(1)〜(5)を行う本発明例に対して、粉砕回転数の決定後は回転数を固定して粉砕するケースを比較例とした。本発明の効果を確認するために、本発明例と比較例において、4時間おきに粉砕炭を採取し、粒度測定を実施した。本発明例と比較例について、粉砕開始からの粉砕炭粒度(平均粒度)の推移を図2に示す。これによれば、本発明例および比較例は、粉砕開始直後はいずれも粉砕炭の平均粒度は0.64mmであり、粉砕開始から4時間まではほぼその粉砕粒度のまま推移した。しかし、その後は、比較例の場合は平均粒径のバラツキが目立ち始めた。一方、本発明例では、4時間おきに原料粒度および原料水分の測定を行い、パラメーターC/e,nと負荷電流値A(目標値)の見直しを行い、目標とする負荷電流値Aを満たすための回転数制御を行ったため、平均粒径バラツキは効果的に抑制された。これにより本発明の有効性を確認できた。 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)
或る銘柄またはハードグローブ指数値の石炭について、予め複数の異なる水分量の石炭を粉砕機で粉砕し、その粉砕条件および粉砕結果に基づき、下記(1)式を用いてパラメーターC/e,nを算出し、石炭の水分量とパラメーターC/e,nとの関係を求めておき、
前記或る銘柄またはハードグローブ指数値の石炭を粉砕機で粉砕するに当たり、粉砕前の石炭の粒度(g0)と水分量(w)を測定し、予め求められている石炭の水分量とパラメーターC/e,nとの関係に基づき、水分量(w)に対応するパラメーターC/e,nを求め、このパラメーターC/e,nと、粉砕前の石炭の粒度(g0)に基づき、下記(1)式を用いて、目標とする粉砕後の石炭の粒度(g)が得られる粉砕機の負荷電流値を求め、該負荷電流値に基づき粉砕機の電流を調整することを特徴とする石炭の粉砕方法。
(A-A0)*V/Q={(C/e)/(n-1)}*{D(1-n)Γ((1+m-n)/m)-D0 (1-n)Γ((1+m0-n)/m0)} …(1)
ただし A:粉砕機の負荷電流値であって、粉砕量一定時の5分間平均電流値(A)
A0:無負荷時の粉砕機の負荷電流値(A)
C:粉砕特性パラメーター(kg/m・s)
D:粉砕後のロージンラムラー粒度特性数(m)
D0:粉砕前のロージンラムラー粒度特性数(m)
V:電圧(V)
Q:粉砕機への原料投入速度(kg/s)
e:粉砕効率(−)
m:粉砕後のロージンラムラー均等数(−)
m0:粉砕前のロージンラムラー均等数(−)
n:ルイス式のべき数
Γ:ガンマ関数 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
複数の異なるハードグローブ指数値の石炭について、予め複数の異なる水分量の石炭を粉砕機で粉砕し、その粉砕条件および粉砕結果に基づき、下記(1)式を用いてパラメーターC/e,nを算出し、石炭のハードグローブ指数値および水分量とパラメーターC/e,nとの関係を求めておき、
或るハードグローブ指数値の石炭を粉砕機で粉砕するに当たり、粉砕前の石炭の粒度(g0)と水分量(w)を測定し、予め求められている石炭のハードグローブ指数値および水分量とパラメーターC/e,nとの関係に基づき、水分量(w)に対応するパラメーターC/e,nを求め、このパラメーターC/e,nと、粉砕前の石炭の粒度(g0)に基づき、下記(1)式を用いて、目標とする粉砕後の石炭の粒度(g)が得られる粉砕機の負荷電流値を求め、該負荷電流値に基づき粉砕機の電流を調整することを特徴とする石炭の粉砕方法。
(A-A0)*V/Q={(C/e)/(n-1)}*{D(1-n)Γ((1+m-n)/m)-D0 (1-n)Γ((1+m0-n)/m0)} …(1)
ただし A:粉砕機の負荷電流値であって、粉砕量一定時の5分間平均電流値(A)
A0:無負荷時の粉砕機の負荷電流値(A)
C:粉砕特性パラメーター(kg/m・s)
D:粉砕後のロージンラムラー粒度特性数(m)
D0:粉砕前のロージンラムラー粒度特性数(m)
V:電圧(V)
Q:粉砕機への原料投入速度(kg/s)
e:粉砕効率(−)
m:粉砕後のロージンラムラー均等数(−)
m0:粉砕前のロージンラムラー均等数(−)
n:ルイス式のべき数
Γ:ガンマ関数 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
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