JP2016168590A - Coal feed amount control method to coal crushing mill, and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coal feed amount control method to a coal crushing mill, and a device therefor, capable of stabilizing the coal feed amount of coal inputted into the coal crushing mill.SOLUTION: When coal cut out from a coal hopper is fed into a coal crushing mill by a coal feeder and dried, a coal amount to be fed into the coal crushing mill is correctively calculated from the weight of the coal hopper and speed of the coal feeder, and the coal feed amount is controlled based on the calculation result.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for controlling the amount of coal supplied to a coal crushing mill and a coal feed amount control device.

  In the blast furnace, coke is mainly charged together with iron ore and sintered ore, hot air is blown from the tuyere, and iron ore is reduced and melted to produce hot metal. In recent years, a technique has been developed in which pulverized coal obtained by pulverizing coal into the blast furnace is blown into the blast furnace through a tuyere. Since pulverized coal is cheaper and more combustible than coke, it is used in many blast furnaces and contributes greatly to rationalization in hot metal production. In addition, by increasing the amount of pulverized coal injected into the blast furnace, it is possible to reduce the load on the coke oven, and since pulverized coal injecting into the blast furnace also contributes to prolonging the life of the coke oven, It is suitable for the blowing operation.

  However, in the operation of injecting a large amount of pulverized coal into the blast furnace, it is important to stabilize the heat balance in the blast furnace, which is required to stabilize the amount of pulverized coal injection. The reason is that if the amount of pulverized coal injection is unstable, the heat balance in the blast furnace deteriorates, causing problems such as poor furnace conditions and clogging of the pulverized coal injection piping. The pulverized coal injection equipment to the blast furnace includes a coal pulverization mill that pulverizes coal and dries it with hot air to form pulverized coal, and a coal feeder that supplies coal in a coal hopper to the coal pulverization mill. It is configured.

  Conventionally, the following techniques are known as the pulverized coal blowing method and its equipment. That is, the increase / decrease in the amount of coal in the coal hopper is measured, the increase / decrease amount and the actual value of the amount of coal supplied to the coal crushing mill are calculated, and the amount of coal input into the coal hopper is controlled based on the calculation result. There is a way.

  Further, in Patent Document 1, a combustion exhaust gas thermometer is provided in a coal pulverization mill, and the ratio is obtained by comparing the combustion exhaust gas temperature measured with this thermometer with the preset equipment management reference temperature of the hot air generator, and further pulverizing. Disclosed is a blast furnace blowing pulverized coal heating / drying control device having a combustion exhaust gas amount calculation function for obtaining a reference combustion exhaust gas amount corresponding to a target coal supply amount supplied to a mill.

  Furthermore, in Patent Document 2, the change in temperature at the inlet of the coal mill necessary to compensate for the sensible heat of the amount of coal supplied to the coal crushing mill is estimated, and the damper opening degree command is obtained by multiplying the estimated value by a coefficient. A method for controlling the temperature at the exit of the grinding mill is disclosed.

Japanese Utility Model Publication No. 4-69439 JP 56-84648 A

  However, among the above-described conventional techniques, the method of calculating the increase / decrease amount of the hopper weight with the actual value of the amount of coal supplied to the coal crushing mill is slow in response of the load cell for measuring the hopper weight, and abrupt fluctuations. Since the moving average process is performed to suppress it, there is a problem that a time lag occurs and a deviation between the actual coal supply amount and the calculated value occurs.

  In addition, in the method described in Patent Document 1, the variation in the amount of coal supplied to the coal pulverization mill has not been studied. If the amount of coal supply varies, the response is slow if only the gas amount is adjusted. There was a problem that the dry state of the film became uneven.

  Furthermore, the method described in Patent Document 2 is a technique that only adjusts so that the temperature at the coal pulverization mill outlet does not drop below a certain temperature. There was a problem that it was difficult to keep the temperature at the exit of the grinding mill constant.

  Therefore, in all of the above prior arts, the amount of coal input to the coal pulverization mill varies, and when drying with a high-temperature circulating gas, sufficient drying cannot be performed, and the temperature variation at the coal pulverization mill outlet increases. The problem remains. As a result, temperature fluctuations at the coal pulverization mill outlet resulted in fluctuations in the amount of pulverized coal injected into the blast furnace, leading to deterioration of the heat balance in the blast furnace.

  The present invention proposes a coal supply control method for a coal crushing mill and an apparatus therefor that can stabilize the amount of coal supplied to the coal crushing mill in view of the above-described circumstances of the prior art. The purpose is to do.

  The inventors have made various studies in order to develop a method for controlling the amount of coal supply to a coal mill and an apparatus therefor that can solve the above-described problems of the prior art. As a result, when coal is fed into the coal crushing mill using the coal hopper and the coal feeder, the coal is stably supplied to the coal crushing mill by controlling based on the weight of the coal hopper and the speed of the coal feeder. The present invention was developed by finding that it can be supplied.

  That is, the present invention corrects the amount of coal supplied to the coal pulverization mill from the weight of the coal hopper and the speed of the coal feeder when the coal cut from the coal hopper is supplied to the coal pulverization mill by the coal feeder and pulverized. The present invention resides in a coal feed amount control method for a coal crushing mill, characterized in that the coal feed amount is controlled based on the computation result.

  The present invention also includes a coal hopper, a coal feeder that conveys the coal supplied from the coal hopper, and a coal crushing mill that dry pulverizes the coal conveyed by the coal feeder. It is composed of a control device that corrects the amount of coal supplied to the crushing mill from the weight of the coal hopper and the speed of the coal feeder, and controls the amount of coal supply based on the calculation result. There is a coal feed control device to the coal crushing mill.

In the method and apparatus for controlling the amount of coal supplied to the coal crushing mill according to the present invention,
(1) Calculate a coal supply base value based on the number of revolutions of the coal feeder; calculate a coal weight change amount by calculating a change amount per unit time of the weight of the coal hopper for each sampling time; A coal feed amount base value integrated value is obtained by calculating for each sampling time based on the coal amount base value; a correction coefficient for the coal feed amount is calculated from the coal weight change amount and the coal feed amount base value integrated value; Calculating the actual value of coal supply control from the basic value of coal supply and the correction coefficient; controlling the amount of coal supply based on the actual value;
(2) As a correction coefficient used for calculating the actual value of the coal supply amount control, a value obtained by multiplying the correction coefficient of the coal supply amount by a correction coefficient based on the actual moisture content of coal supplied,
Is considered to be a preferred solution.

  According to the present invention, the amount of coal supplied to the coal pulverization mill can be stabilized, which leads to stabilization of the amount of pulverized coal injected into the blast furnace and the heat in the blast furnace. Since the balance can be stabilized, the amount of coke used can be reduced.

It is a figure which shows an example of the coal grinding mill equipment in this invention. It is a block diagram which shows an example of the system configuration | structure of this invention.

  FIG. 1 is a diagram showing an example of blast furnace pulverized coal injection equipment centered on a coal pulverization mill. In this figure, coal 7 is supplied from a coal hopper 1 to a coal feeder 2. The coal feeder 2 is driven by a motor 3, and the coal 7 on the coal feeder 2 is supplied from the inlet 4a into the coal crushing mill 4 by the driving. The coal 7 introduced into the coal pulverization mill 4 is pulverized here and dried by hot air introduced from the lance 5, and is discharged as pulverized coal 8 from the outlet 4b. Thereafter, the discharged pulverized coal 8 is supplied to the blast furnace 6.

  The present invention proposes a control method and a control device for optimizing the amount of coal supplied into the coal crushing mill 4 as shown in FIG. That is, the feature of the present invention is that the configuration as shown in FIG. 2 is adopted, the coal crushing mill 4 calculates the amount of coal to be supplied from the weight of the coal hopper 1 and the speed of the coal feeder 2, and the calculation result. Therefore, the amount of coal supply of the coal feeder 2 is controlled.

  In the present invention, by performing such control, the fluctuation range of the coal supply amount of the coal 7 to the coal crushing mill 4 can be reduced. Thereby, the temperature fluctuation | variation in the exit 4b of the coal grinding mill 4 can be made small, and the blowing amount of the pulverized coal 8 to the blast furnace 6 can be stabilized. As a result, the heat balance in the blast furnace 6 is stabilized, and the amount of coke used in the blast furnace 6 can be reduced.

  Hereinafter, a specific example of the method for controlling the amount of coal supply to the coal crushing mill according to the present invention will be described. In the following example, from the weight of the coal hopper 1 and the speed of the coal feeder 2, the control device supplies the coal pulverization mill 4 from the coal feeder 2 using the following formulas (1) to (5). Perform correction calculation of the amount of coal supply.

である。 First, in the control device, the base value of the coal supply amount is calculated by the equation (1) based on the rotation speed of the coal feeder at the lower part of the coal hopper, and the base value of the coal supply amount is obtained.

It is.

である。 Next, the amount of change in the weight of the coal hopper per unit time is calculated for each sampling time according to the equation (2) to obtain the amount of change in the coal weight.

It is.

である。 Next, an integral value for each sampling time is calculated based on the coal supply amount base value of equation (1) to obtain the coal supply amount base value integral value.

It is.

ここで、（４）式のＤは、給炭量基値のある時間の積分値で、ある時間の石炭重量変化量を割った値の移動平均値（ｎサンプリング数）であり、本演算結果を補正係数とする。 Next, the following equation (4) is calculated based on the coal weight change obtained by equation (2) and the coal supply base value integral value obtained by equation (3), and the correction coefficient for the coal supply amount Ask for.

Here, D in the equation (4) is an integral value of the coal supply amount base value for a certain time, which is a moving average value (n sampling number) obtained by dividing the coal weight change amount for a certain time. Is a correction coefficient.

ここで、（５）式で求めた値を給炭量制御のＰＶ値とすることで、給炭量が安定化し、石炭粉砕ミル出口での温度ばらつきが低下する効果が得られる。 Based on the correction coefficient D obtained by the above correction calculation, the actual value (PV value) used for the coal supply amount control is obtained by the equation (5).

Here, by using the value obtained by the equation (5) as the PV value for the coal supply control, the effect of stabilizing the coal supply and reducing the temperature variation at the coal crushing mill outlet is obtained.

ここで、Ｅ ：供給石炭水分補正係数
である。 In a further preferred embodiment, the value E · D obtained by multiplying the correction coefficient E obtained from the actual moisture content of the coal supplied to the correction coefficient D is used as the correction coefficient. In that case, the actual value (PV value) used for coal supply amount control is calculated | required by (6) Formula. The correction coefficient E is calculated from a table obtained from past results.

Here, E: Supply coal moisture correction coefficient.

  The coal pulverization mill control method and apparatus for the coal pulverization mill according to the present invention can be sufficiently obtained by using the correction coefficient D as the correction coefficient and using the value obtained by the equation (5) as the PV value for the coal supply control. The amount of coal supply is stabilized, and an effect of reducing temperature variations at the outlet of a sufficient coal grinding mill can be obtained. Here, using the value E · D obtained by multiplying the correction coefficient D by the correction coefficient E obtained from the actual moisture content of the coal supplied as the correction coefficient D, the value obtained by the equation (6) is used as the PV for coal supply control. By setting the value, it is possible to further stabilize the amount of coal supply and to obtain an effect of further reducing temperature variation at the coal pulverization mill outlet.

Hereinafter, embodiments of the present invention will be described by way of examples.
As shown in FIG. 1, using a blast furnace pulverized coal blowing device (PCI) comprising a coal hopper 1, a coal feeder 2, and a coal crushing mill 4, a correction coefficient D according to the above-described equations (1) to (5). The correction value E is obtained in accordance with the present invention example (equipment 1 to 3) in which the PV value is obtained using the above and the amount of coal supplied to the coal crushing mill 4 is controlled by the PV value and the above-described equations (1) to (6). -The present invention example (equipment 4-6) which calculated | required PV value using D, and controlled the coal supply amount to the coal crushing mill 4 with PV value, and the conventional coal hopper 1 without using a correction coefficient In the comparative example (equipment 7 to 8) in which the amount of coal input to the coal hopper 1 is controlled according to the weight change, pulverized coal is actually injected, and the temperature fluctuation at the outlet 4b of the coal crushing mill 4 is varied. It asked and compared for every equipment. The variation in the mill outlet temperature was determined as the difference between the maximum and minimum deviation temperatures relative to the target temperature during operation. The results are shown in Table 1 below.

  From the results of Table 1, the example of the present invention in which the amount of coal supply was controlled by the correction coefficient showed significantly less variation in the outlet temperature of the coal crushing mill than the comparative example in which the amount of coal supply was controlled by the hopper weight change. It was found that the amount of coal supplied to the grinding mill could be stabilized. Moreover, when the equipment 1-3 using the correction coefficient D is compared with the equipment 4-6 using the correction coefficient E • D, the equipment 4-6 using the correction coefficient E • D has the correction coefficient D It turned out that the dispersion | variation in outlet temperature can be reduced more fully compared with the used equipment 1-3. As a result, the amount of pulverized coal injected into the blast furnace can be stabilized, and the heat balance in the blast furnace can be stabilized to reduce the amount of coke used.

  According to the method and apparatus for controlling the amount of coal supplied to the coal mill of the present invention, it is possible to stabilize the amount of pulverized coal injected into the blast furnace by stabilizing the amount of coal supplied to the coal crushing mill. Thus, the heat balance in the blast furnace is stabilized, so that the amount of coke used can be reduced. As a result, by using this as, for example, pulverized coal injection equipment into a blast furnace, the life of the furnace can be improved, and its industrial value is great.

DESCRIPTION OF SYMBOLS 1 Coal hopper 2 Coal feeder 3 Motor 4 Coal crushing mill 4a Inlet 4b Outlet 5 Lance 6 Blast furnace 7 Coal 8 Pulverized coal

Claims (6)

  When the coal cut out from the coal hopper is supplied to the coal pulverization mill by the coal feeder and pulverized, the amount of coal supplied to the coal pulverization mill is corrected from the weight of the coal hopper and the speed of the coal feeder, and the calculation result A method for controlling the amount of coal supply to a coal crushing mill, wherein the amount of coal supply is controlled based on the above. Calculating a coal supply base value based on the rotational speed of the coal feeder;
The amount of change in the weight of the coal hopper per unit time is calculated for each sampling time to determine the amount of change in coal weight;
An integral value of the coal supply amount base value is calculated by calculating for each sampling time based on the coal supply amount base value;
Calculating a correction coefficient of the coal supply amount from the coal weight change amount and the coal supply base value integral value;
Calculating an actual value of the coal supply amount control from the coal supply amount base value and the correction coefficient;
Controlling the amount of coal supply based on the actual value;
The coal feed amount control method for a coal crushing mill according to claim 1.   The correction coefficient used for calculating the actual value of the coal supply amount control is a value obtained by multiplying the correction coefficient of the coal supply amount by a correction coefficient based on the actual moisture content of coal supplied. The method for controlling the amount of coal supplied to the coal crushing mill according to 2.   Coal to be supplied to the coal pulverization mill, comprising a coal hopper, a coal feeder that conveys coal supplied from the coal hopper, and a coal pulverization mill that dry pulverizes the coal conveyed by the coal feeder Coal pulverization characterized in that it is composed of a coal supply amount control device that corrects the amount from the weight of the coal hopper and the speed of the coal feeder and controls the amount of coal supply based on the calculation result Coal feed amount control device to the mill.   The coal supply amount control device: calculates a coal supply basic value based on the number of revolutions of the coal feeder; calculates a change amount per unit time of the coal hopper weight for each sampling time, and changes a coal weight change amount A coal feed amount base value integral value obtained by calculating every sampling time based on the coal feed amount base value; a coal feed amount correction coefficient from the coal weight change amount and the coal feed amount base value integral value The coal value according to claim 4, wherein: a coal supply amount control actual value is calculated from the coal supply amount base value and the correction coefficient; and a coal supply amount is controlled based on the actual value. Coal feed control device for crushing mill.   The correction coefficient used for calculating the actual value of the coal supply amount control is a value obtained by multiplying the correction coefficient of the coal supply amount by a correction coefficient based on the actual moisture content of coal supplied. An apparatus for controlling the amount of coal supplied to the coal crushing mill according to claim 5.

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