CN110369057B - Method for acquiring coal powder flow of powder pipe in double-inlet and double-outlet steel ball milling direct-blowing type powder making system - Google Patents

Method for acquiring coal powder flow of powder pipe in double-inlet and double-outlet steel ball milling direct-blowing type powder making system Download PDF

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CN110369057B
CN110369057B CN201910588062.1A CN201910588062A CN110369057B CN 110369057 B CN110369057 B CN 110369057B CN 201910588062 A CN201910588062 A CN 201910588062A CN 110369057 B CN110369057 B CN 110369057B
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coal
powder
tank
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primary air
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胡昊
向勇林
廖冰遥
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Datang Huayin Electric Power Co ltd
Hunan Xiangtan Power Generation Co ltd
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Datang Huayin Electric Power Co ltd
Hunan Xiangtan Power Generation Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C17/00—Disintegrating by tumbling mills, i.e. mills having a container charged with the material to be disintegrated with or without special disintegrating members such as pebbles or balls
    • B02C17/18—Details
    • B02C17/1805—Monitoring devices for tumbling mills
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F3/00—Measuring the volume flow of fluids or fluent solid material wherein the fluid passes through the meter in successive and more or less isolated quantities, the meter being driven by the flow

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Abstract

The invention discloses a method for acquiring the pulverized coal flow of a pulverized pipe in a double-inlet and double-outlet steel ball milling direct-blowing pulverizing system, which comprises the following steps: respectively obtaining a relational expression or a relational curve of the coal powder amount in the large coal mill tank and the surface area of the coal powder exposed to primary air under the working condition that the steel ball is submerged by the coal powder and the working condition that the steel ball is pressed by the coal powder, and obtaining the coal powder amount in the large coal mill tank at the moment to be measured; obtaining the surface area of the coal powder exposed to the primary air at the moment to be detected by using the relational expression or the relational curve and the coal powder amount in the large tank of the coal mill at the moment to be detected; the flow of the pulverized coal in the primary air-powder pipe is calculated based on the surface area of the pulverized coal exposed to primary air at the moment to be measured and the air quantity.

Description

Method for acquiring coal powder flow of powder pipe in double-inlet and double-outlet steel ball milling direct-blowing type powder making system
Technical Field
The invention belongs to the technical field of boilers, and particularly relates to a method for acquiring the coal powder flow of a powder pipe in a double-inlet and double-outlet steel ball milling direct-blowing type powder making system.
Background
The real-time fuel quantity entering a hearth of the direct-fired pulverizing system can be calculated in a steady state, but during the start-stop pulverizing system, the concentration of pulverized coal in a primary air-pulverized coal pipe is constantly changed, namely the fuel quantity entering the hearth is changed, the accuracy of the fuel quantity entering the hearth directly influences a fuel control instruction, and inaccurate fuel feedback can cause the reverse regulation of the fuel instruction, so that the temperature and the pressure of main steam of a boiler are out of control, and the safety and the economy of a unit are influenced. Therefore, it is crucial to accurately obtain the coal powder concentration/flow rate in the primary air-powder pipe, however, at present, the measurement of coal powder concentration includes microwave method, photoelectric detection method, laser method, electrostatic method, etc., but none of them are mature enough, and are not used much in power production, and the effect is not ideal, each power plant generally adopts a fixed value (0.6-0.85) as the coal powder concentration in the primary air-powder pipe, for the direct-blowing coal pulverizing system of the double-inlet and double-outlet steel ball mill, in the start and stop of the coal feeder, especially in the start and stop of the coal mill, the change of the coal powder concentration is very complex, even if the gradual concentration is adopted, the actual change curve cannot be well fitted, so that the fuel disturbance caused by the start and stop of the coal pulverizing system has not been well eliminated or weakened to the maximum extent, the fuel feedback distortion often occurs, the air door capacity of the coal mill is reversely adjusted, the main steam pressure/, affecting the safety and economy of the unit.
Disclosure of Invention
The invention aims to provide a method for acquiring the coal powder flow of a powder pipe in a double-inlet and double-outlet steel ball milling direct-blowing type pulverizing system, which can realize the real-time detection of the coal powder flow in a primary air branch pipe, calculate the surface area of the coal powder exposed to primary air at the moment corresponding to the working condition through the real-time changing working condition, further obtain a more accurate coal powder flow value through theoretical calculation, solve the problem that the existing coal powder flow value is brought by an estimation value obtained according to experience, provide an accurate parameter basis for a fuel control instruction, and further ensure the safety and the economy of a unit.
The invention provides a method for acquiring the pulverized coal flow of a pulverized pipe in a double-inlet and double-outlet steel ball milling direct-blowing pulverizing system, which comprises the following steps:
s1: respectively obtaining a relational expression or a relational curve of the coal powder amount in the large coal mill tank and the surface area of the coal powder exposed to primary air under the working condition that the steel ball is submerged by the coal powder and the working condition that the steel ball is pressed by the coal powder, and obtaining the coal powder amount in the large coal mill tank at the moment to be measured;
s2: obtaining the surface area of the coal powder exposed to the primary air at the moment to be detected by using the relational expression or the relational curve and the coal powder amount in the large tank of the coal mill at the moment to be detected;
s3: calculating the flow rate of the pulverized coal in the primary air-powder pipe based on the surface area of the pulverized coal exposed to primary air at the moment to be measured and the air quantity;
f(S,AF)＝KSaAF b
wherein f (S, A)F) The flow rate of the pulverized coal in the primary air-powder pipe at the moment to be measured is shown, S represents the surface area of the pulverized coal exposed to primary air at the moment to be measured, AFThe air volume is shown, a and b are indexes, and K is a proportionality coefficient.
According to the invention, the relation between the amount of the pulverized coal in the large coal mill tank and the surface area of the pulverized coal exposed to primary air is obtained by obtaining the relational expression or the relational curve between the amount of the pulverized coal in the large coal mill tank and the surface area of the pulverized coal exposed to primary air under the working condition that the pulverized coal submerges the steel ball and the working condition that the pulverized coal is pressed by the steel ball, so that the surface area of the pulverized coal exposed to primary air at the corresponding moment can be calculated in real time after the amount of the pulverized coal in the large coal mill tank is obtained, and further the flow of the. The reliability of the obtained surface area of the pulverized coal exposed to the primary air can be improved by theoretically deducing the relational expression of the method, and the accuracy of the final calculation result is further improved.
Preferably, the relation between the amount of pulverized coal in the large tank of the coal mill and the surface area of the pulverized coal exposed to primary air under the condition that the pulverized coal submerges the steel ball is as follows:
Figure BDA0002115153320000021
wherein m represents the amount of coal dust in the large coal mill tank, B represents the length of the large coal mill tank, R represents the radius of the large coal mill tank, and rho representscIs the bulk density of coal dust, VbIs the volume of the steel ball.
Preferably, the relation between the amount of pulverized coal in the large tank of the coal mill and the surface area of the pulverized coal exposed to primary air under the working condition that the pulverized coal is pressed by the steel ball is as follows:
Figure BDA0002115153320000022
wherein m represents the amount of coal dust in the large coal mill tank, B represents the length of the large coal mill tank, R represents the radius of the large coal mill tank, and rho representscIs the bulk density of the coal dust.
Preferably, the coal powder amount in the large coal mill tank at the moment to be measured is equal to the accumulation of the difference between the pulverizing speed p (t) in the large coal mill tank and the flow f (t) of the fuel entering the furnace in the period from the starting moment of the coal mill to the moment to be measured;
the coal pulverizing speed p (t) represents the pulverized coal amount ground in the large coal mill tank in unit time, the furnace entering fuel flow rate f (t) represents the pulverized coal amount blown into the hearth from the large coal mill tank in unit time, and the pulverized coal flow rate in the primary air powder pipe at the moment to be measured is the fuel flow rate f (t) entering the hearth from the large coal mill tank.
Preferably, a closed loop calculation loop is constructed by using the coal dust amount m (t), the coal pulverizing speed p (t) and the furnace entering fuel flow f (t) in the coal mill big tank, and the equation set of the closed loop calculation loop is as follows:
Figure BDA0002115153320000023
Figure BDA0002115153320000031
Figure BDA0002115153320000032
f(t)＝f(S,AF)
wherein m (t represents the powder amount m in the large tank of the coal mill, c (t) is the coal supply flow rate, p (t) is the pulverizing speed, r (t is the coal/powder ratio, y (r) is the pulverizing efficiency broken line function corresponding to the coal/powder ratio, and f (t) is the fuel flow rate entering the furnace.
Preferably, the value range of the proportionality coefficient K is: [0.04,0.045].
Preferably, the values of the indices a, b are both 1.
Advantageous effects
The method for acquiring the coal dust flow of the powder pipe in the double-inlet and double-outlet steel ball milling direct-blowing type powder making system can accurately calculate the coal dust flow in the primary air dust pipe compared with the prior art in the period of quick load change or start and stop of the powder making system, particularly in dozens of minutes when the material level of a coal mill is not established. The coal powder amount m in the large coal mill tank and the single coal mill coal amount m measured from the site are obtained by accumulating the difference between the coal powder making speed and the fuel amount f (t) entering the furnace, and the coal powder amount m measured from the siteMachine capacity air flow AF(t) according to the relation f (t) 0.04s (m) aF(t) calculating the required fuel charge amount f (t) in real time, and sequentially forming a closed loop calculation circuit to provide a basis for accurate execution of the fuel control regulation instruction.
Drawings
FIG. 1 is a schematic structural view of a pulverized coal charging furnace according to the present invention;
FIG. 2 is a schematic illustration of a coal pulverizer provided by the present invention, wherein (a) the illustration is an axial view of a large coal pulverizer tank and (b) the illustration is a spatial view of the large coal pulverizer tank;
FIG. 3 is a graph of the amount of coal in a large tank of a coal pulverizer according to the method of the present invention versus the area exposed to primary air;
FIG. 4 is a DCS logic control diagram provided by the present invention;
FIG. 5 is a graph showing the actual material level of a coal pulverizer provided by the present invention versus the calculated amount of coal dust in the large tank of the coal pulverizer;
FIG. 6 is a graphical representation of the pulverized coal ratio versus pulverizing efficiency function provided by the present invention.
Detailed Description
The present invention will be further described with reference to the following examples.
Firstly, the process of charging pulverized coal into the furnace is described as follows with reference to fig. 1: the coal feeder puts raw coal into a large tank of the coal mill, the flow rate is c (t) (the amount of raw coal fed into the large tank of the coal mill in unit time) is ground into coal powder after a period of time, the coal powder grinding speed p (t) (the amount of coal powder ground in unit time) is increased along with the increase of the amount of coal in the large tank, when the coal feeding flow rate and the speed of converting the coal powder into the coal powder reach the balance, namely c (t) ═ p (t), the coal amount in the large tank is not increased, simultaneously along with the increase of the coal powder grinding speed p (t), the coal powder amount in the large tank is increased, the coal powder concentration in a powder pipe is also increased, the flow rate of blown coal powder f (t) is increased (after the coal powder in the large tank enters a separator, the coarse powder is returned to the large tank, the fine powder is brought into a hearth by primary air, the flow rate of the blown coal powder f (t) is f (t), when f) ═ p (t) (c (t), dynamic balance is achieved, and the material level of the coal mill is stable.
Wherein byLong-time research and data lookup find that the dust raising amount is related to a plurality of factors including the surface area, the air volume, the water content and the bulk density of the coal dust, the water content of the coal dust in a large tank of the coal mill can be ignored, the bulk density of the coal dust can be calculated according to the density of new coal dust, the surface area of the coal dust exposed to primary air is S, and the air volume signal is AFDust amount per unit time f in large tank of coal mill1(S,AF) Can be expressed as f1(S,AF)＝K1SaAF b，K1The proportion coefficient is, however, based on the above coal powder charging process, it can be known that after the coal powder in the large tank of the coal mill enters the separator, the coarse powder is returned to the large tank, and the fine powder is brought into the furnace chamber by the primary air, so that the concentration of the coal powder in the powder pipe is less than that of the coal powder in the large tank, and a coefficient K needs to be multiplied2The flow rate of the pulverized coal in the primary air-powder duct can be expressed as f (S, A)F)＝K1K2SaAF b＝KSaAF bThe research shows that the value range of K is as follows: [0.04,0.045]The values of the indexes a and b are both 1.
From the above, if the flow rate of the pulverized coal in the primary air-powder pipe is to be obtained in real time, it is necessary to know that the surface area of the pulverized coal exposed to the primary air is S and the air volume aFWherein, the air volume AFIn order to obtain the surface area S of the coal powder exposed to the primary air through field measurement, the surface area S of the coal powder is changed in real time, and the surface area S is found to be related to the mass m of the coal powder in the large tank of the coal mill through research, and the relationship between the amount of the coal powder in the large tank of the coal mill and the surface area of the coal powder exposed to the primary air is analyzed according to the working condition that the steel ball is submerged in the coal powder and the working condition that the coal powder:
a: firstly, considering the condition that the steel ball is submerged by the pulverized coal, the surface area of the pulverized coal exposed to primary air is S, and the method comprises the following steps: l × B, mass m of coal powder, present: m ═ S0×B-Vb)×ρc；
Wherein the content of the first and second substances,
Figure BDA0002115153320000041
l is a coal mill tank as shown in FIGS. 2 (a) and (b)The chord length of the cross section of the inner pulverized coal, B is the length of a large tank of the coal mill, R is the radius of the large tank of the coal mill, and S0The cross section area of the coal powder in the large tank of the coal mill is the cross section area of the coal powder in the large tank of the coal mill;
and further deducing a relational expression of the coal powder amount in the large coal tank and the surface area of the coal powder exposed to primary air as follows:
Figure BDA0002115153320000042
for example, for a BBD4060 coal mill, where the parameter B is 6 and R is 2, the bulk density ρ of the coal dustc＝0.5，VbThe relation between the amount of the coal powder in the large tank of the coal mill and the surface area of the coal powder exposed to primary air under the working condition that the coal powder submerges the steel ball is as follows:
Figure BDA0002115153320000051
b: secondly consider under the working condition that the buggy is pushed down by the steel ball, when the coal pulverizer rotated, the steel ball that falls to the ground can roughly be regarded as the isodiametric closest packing, and the space occupancy of hexagonal closest packing or cubic closest packing all is 74.05%, consider that there is the buggy in the clearance, and the space occupancy of steel ball that falls to the ground is slightly low, according to 70% estimation, the quality m of buggy exists: m ═ S0×B×30％×ρcThe surface area of the coal powder exposed to primary air is S, and the surface area is similar to that of the coal powder: s is 0.32/3×L×B；
And further deducing a relational expression of the coal powder amount in the large coal tank and the surface area of the coal powder exposed to primary air as follows:
Figure BDA0002115153320000052
for example, for a BBD4060 coal mill, where the parameter B is 6 and R is 2, the bulk density ρ of the coal dustc＝0.5，VbThe relation between the amount of the coal powder in the large tank of the coal mill and the surface area of the coal powder exposed to primary air under the working condition that the coal powder submerges the steel ball is as follows:
Figure BDA0002115153320000053
according to the relational expression of the amount of the pulverized coal in the large tank of the coal mill and the surface area of the pulverized coal exposed to the primary air under the two working conditions, the relational curve of the amount of the pulverized coal and the exposed surface area shown in fig. 3 is obtained, and the exposed surface area can be calculated when the amount of the pulverized coal in the large tank is obtained from the curve.
Based on the above principle explanation, the method for obtaining the pulverized coal flow of the powder pipe in the double-inlet and double-outlet steel ball milling direct-blowing pulverizing system provided by the invention comprises the following steps:
s1: respectively obtaining a relational expression or a relational curve of the coal powder amount in the large coal mill tank and the surface area of the coal powder exposed to primary air under the working condition that the steel ball is submerged by the coal powder and the working condition that the steel ball is pressed by the coal powder, and obtaining the coal powder amount in the large coal mill tank at the moment to be measured;
s2: obtaining the surface area of the coal powder exposed to the primary air at the moment to be detected by using the relational expression or the relational curve and the coal powder amount in the large tank of the coal mill at the moment to be detected;
s3: and calculating the flow rate of the coal dust in the primary air-powder pipe based on the surface area of the coal dust exposed to the primary air at the moment to be measured and the air quantity.
To illustrate the implementation of the present invention, the present invention involves DCS logic, forming a closed loop computational loop. As shown in fig. 4, according to the logic diagram and the above-mentioned flow, the implementation process of the present invention is briefly described as follows: the following equation set is involved in the closed loop calculation loop:
Figure BDA0002115153320000061
Figure BDA0002115153320000062
Figure BDA0002115153320000063
f(t)＝0.04s(m)AF(t) (6)
wherein m (t) represents the powder amount m in the large tank of the coal mill, c (t) is the coal supply flow rate measured on site, p (t) is the powder making speed, r (t) is the coal/powder ratio, y (r) is a powder making efficiency broken line function corresponding to the coal/powder ratio (a relation curve of the coal powder ratio and the powder making efficiency is found out through experience), f (t) is the fuel flow rate entering the furnace and is equal to the coal powder flow rate f (S, A) in a primary air powder pipeF) And s (m) is a relation of the amount of coal powder in the large tank of the coal machine and the surface area, AFAnd (t) is the air flow of the single mill capacity, and is measured on site. In the embodiment of the present invention, a polygonal line function y (r) of pulverizing efficiency corresponding to a coal/powder ratio is shown in fig. 6, an abscissa represents a coal powder ratio, and an ordinate represents pulverizing efficiency, and the following table 1 is obtained through experience:
TABLE 1
Ratio of pulverized coal Efficiency of pulverizing
0.2 36
1 42
10 48
100 48
Therefore, according to the above equation set and the DCS logic diagram shown in fig. 4, the closed loop calculation loop is formed as follows: the coal/powder ratio at the time t can be updated by using a formula (3) based on the powder amount m in the large tank of the coal mill, the surface area s (m) of the formula (1) and the surface area s (m) of the formula (2) can be further used for calculating the fuel flow rate f (t) entering the furnace at the time t by using a formula (6) according to the surface area s (m), the powder making speed p (t) can be calculated by using a formula (4) according to the coal/powder ratio at the time t, and the updating of the powder amount m in the large tank of the coal mill can be realized by using a formula (5) based on the fuel flow rate f (t) entering the furnace and the powder making speed p (t) so as to realize a closed-loop calculation loop, wherein theoretically, when the coal mill is started, the coal entering the tank is ground into powder, the coal and the residual coal powder can be replaced by a pure hysteresis link in a short time, the initial cycle calculation of the closed-loop, the coal/powder ratio is large, the powder preparation efficiency is high, but the coal quantity is small, the powder preparation speed is low, the powder preparation speed is increased along with the increase of the coal quantity, the coal/powder ratio is reduced, the powder preparation efficiency is reduced, the unit of coal supply flow is t/h, after long-time exploration, the powder preparation efficiency is about 30-50, namely about 50% -80% of coal entering a tank is ground into powder after 1 minute, the link can be roughly replaced by a pure hysteresis link, and the time constant is about 90 seconds.
In order to preliminarily verify the correctness of the method, the calculated in-tank powder amount and material level data are exported, the corresponding curve of the three-time start-stop mill is shown in figure 5, the vertical axis represents the material level, the horizontal axis represents the powder amount, three curves in figure 5 represent a curve graph of the in-tank powder amount and material level data in the three-time start-stop process calculated according to the method, the inflection point in the change curve of the in-tank powder amount and material level data is an effective value check point, and as can be seen from the graph, the three curves are all the inflection points (about 100 material levels) at the powder amount of 5-6 tons, so that the reliability of the calculation formula of the in-tank powder amount provided by the method is proved, and the reliability of the closed loop calculation loop constructed by the method is further proved.
Because the cascade self-balancing algorithm is adopted, the fuel main control of the unit No. 4 of the Tang Xiangtan generation Limited company obtains more accurate fuel quantity entering the furnace, and the coordination control quality is greatly improved, wherein the control results of the main steam temperature and pressure in 2 months (only adopting time gradient concentration) in 2018 and 9 months (adopting the cascade self-balancing algorithm) in 2018 are as follows:
the main steam temperature fluctuates by +/-9 ℃ and +/-0.5 MPa in the 2 months under low load, the main steam temperature fluctuates by-28 ℃ in the case of large load change (no mill start and stop), and the main steam temperature fluctuates by +/-10 ℃ and the main steam temperature fluctuates by +/-0.8 MPa in the case of small load fluctuation; when the coal mill is started and stopped, the temperature of the main steam fluctuates by +/-10 ℃; greatly reducing the load and stopping the C grinding, wherein the steam temperature fluctuates to-37 ℃; when the load is stable in 9 months with lower load, the temperature of the main steam fluctuates by +/-1 ℃, when the triangular load changes, the temperature of the main steam fluctuates by +/-4.5 ℃, the pressure fluctuation by +/-0.7 MPa, the D mill is started simultaneously with small load change, the temperature of the main steam fluctuates by-5 ℃, the C mill is stopped simultaneously with large load reduction, and the temperature of the main steam fluctuates by +/-5 ℃. The difference between the average main steam temperature before and after the application of the invention is 6.5 ℃, the coal consumption is reduced by 0.68g/KW main steam, and the electricity generation cost can be saved by 130 ten thousand yuan every year.
It should be emphasized that the examples described herein are illustrative and not restrictive, and thus the invention is not to be limited to the examples described herein, but rather to other embodiments that may be devised by those skilled in the art based on the teachings herein, and that various modifications, alterations, and substitutions are possible without departing from the spirit and scope of the present invention.

Claims (7)

1. A method for obtaining the pulverized coal flow of a pulverized pipe in a double-inlet and double-outlet steel ball milling direct-blowing pulverizing system is characterized by comprising the following steps: the method comprises the following steps:
s1: respectively obtaining a relational expression or a relational curve of the coal powder amount in the large coal mill tank and the surface area of the coal powder exposed to primary air under the working condition that the steel ball is submerged by the coal powder and the working condition that the steel ball is pressed by the coal powder, and obtaining the coal powder amount in the large coal mill tank at the moment to be measured;
s2: obtaining the surface area of the coal powder exposed to the primary air at the moment to be detected by using the relational expression or the relational curve and the coal powder amount in the large tank of the coal mill at the moment to be detected;
s3: calculating the flow rate of the pulverized coal in the primary air-powder pipe based on the surface area of the pulverized coal exposed to primary air at the moment to be measured and the air quantity;
f(S，AF)＝KSaAF b
wherein f (S, A)F) The flow rate of the pulverized coal in the primary air-powder pipe at the moment to be measured is shown, S represents the surface area of the pulverized coal exposed to primary air at the moment to be measured, AFThe air volume is shown, a and b are indexes, and K is a proportionality coefficient.
2. The method of claim 1, wherein: the relational expression of the coal powder amount in the large tank of the coal mill and the surface area of the coal powder exposed to primary air under the working condition that the steel ball is submerged by the coal powder is as follows:
Figure FDA0002115153310000011
wherein m represents the amount of coal dust in the large coal mill tank, B represents the length of the large coal mill tank, R represents the radius of the large coal mill tank, and rho representscIs the bulk density of coal dust, VbIs the volume of the steel ball.
3. The method of claim 1, wherein: the relational expression of the pulverized coal amount in the large tank of the coal mill and the surface area of the pulverized coal exposed to primary air under the working condition that the pulverized coal is pressed by the steel ball is as follows:
Figure FDA0002115153310000012
wherein m represents the amount of coal dust in the large coal mill tank, B represents the length of the large coal mill tank, R represents the radius of the large coal mill tank, and rho representscIs the bulk density of the coal dust.
4. The method of claim 1, wherein: the coal powder amount in the large coal mill tank at the moment to be measured is equal to the accumulation of the difference between the pulverizing speed p (t) in the large coal mill tank and the flow f (t) of the fuel entering the furnace in the period from the starting moment of the coal mill to the moment to be measured;
the coal pulverizing speed p (t) represents the pulverized coal amount ground in the large coal mill tank in unit time, the furnace entering fuel flow rate f (t) represents the pulverized coal amount blown into the hearth from the large coal mill tank in unit time, and the pulverized coal flow rate in the primary air powder pipe at the moment to be measured is the fuel flow rate f (t) entering the hearth from the large coal mill tank.
5. The method of claim 4, wherein: constructing a closed loop calculation circuit by utilizing the coal dust amount m (t), the coal pulverizing speed p (t) and the furnace entering fuel flow f (t) in the coal mill big tank, wherein the equation set of the closed loop calculation circuit is as follows:
Figure FDA0002115153310000021
Figure FDA0002115153310000022
Figure FDA0002115153310000023
f(t)＝f(S，AF)
wherein m (t) represents the powder amount m in the large tank of the coal mill, c (t) represents the coal feeding flow rate, p (t) represents the pulverizing speed, r (t) represents the coal/powder ratio, y (r) represents the pulverizing efficiency broken line function corresponding to the coal/powder ratio, and f (t) represents the fuel flow rate entering the furnace.
6. The method of claim 1, wherein: the value range of the proportionality coefficient K is as follows: [0.04,0.045].
7. The method of claim 1, wherein: the values of the indexes a and b are both 1.
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