JP6801438B2 - Milling plant oxygen concentration controller, milling plant oxygen concentration control method, and program - Google Patents

Description

The present invention relates to a pulverization plant oxygen concentration controller, a pulverization plant oxygen concentration control method, and a program, and is particularly suitable for use in controlling an oxygen concentration in a pulverization plant.

Conventionally, there are the following plants as crushing plants for producing pulverized coal, cement and the like (see Patent Document 1).
First, fuel gas (combustion gas) and combustion air are supplied to a hot gas generator, and hot air is generated as exhaust gas in the hot gas generator. The exhaust gas is supplied to the inside of the crusher that crushes the raw material. The raw material (powder) crushed by the crusher is supplied to the bag filter (filter cloth (fiber cloth or non-woven fabric)) together with the exhaust gas, and is collected by the bag filter. After that, the exhaust gas is boosted by the circulation fan and supplied to the heat gas generator again as circulating gas. The hot air (exhaust gas) generated by the hot gas generator is circulated from the hot gas generator to the hot gas generator via the crusher and the bag filter. Here, the pressure at the entry side position of the crusher is set to a negative pressure (pressure below the atmospheric pressure) so that the pressure inside the crusher and the pressure inside the bag filter are maintained at the negative pressure. In the following description, such a "crushing plant" will be referred to as a "negative pressure type / exhaust gas circulation system crushing plant" as necessary. In addition, the "path through which the exhaust gas circulates" is referred to as a "line" as necessary.

In such a crushing plant such as a negative pressure type / exhaust gas circulation system crushing plant, if the oxygen concentration inside the line becomes high, a dust explosion may occur, so that the oxygen concentration inside the line cannot be increased. On the other hand, when the oxygen concentration inside the line becomes low, water vapor becomes liquid phase inside the line, which may impair the function of the bag filter. Therefore, it is necessary to keep the oxygen concentration inside the line as constant as possible.

Here, there are the following four main disturbances that fluctuate the oxygen concentration inside the line.
First, there is exhaust gas from the hot gas generator and water vapor generated from the raw material (coal) by drying. Second, there is exhaust gas generated from the heat gas generator. Thirdly, there is air (incoming air) that enters the crusher from a bunker or the like because the pressure inside the crusher and the pressure of the bag filter are maintained at a negative pressure. Fourth, from the lower part of the crushing table in order to push the pulverized coal that is about to be discharged to the outside through the gap inside the crusher (the bearing part of the crushing table) back to the flow of the exhaust gas supplied from the heat gas generator 101. There is air (seal air) that is blown in.

As a method of controlling the oxygen concentration inside the line, by injecting air (diluted air) inside the line, the oxygen concentration inside the line is controlled so that the oxygen concentration inside the line becomes the target value (constant). There is.
However, for example, the flow rate of water vapor and the flow rate of exhaust gas vary greatly depending on the water content of the raw material. Further, the ingress air and the seal air affect the load of the heat gas generator (burner load), and the load of the heat gas generator affects the flow rate of the exhaust gas. Therefore, it is not easy to predict the oxygen concentration inside the line in advance.

In this way, since it is not easy to predict the oxygen concentration inside the line in advance, conventionally, the oxygen concentration inside the line is measured, and feedback control is performed so that the measured value becomes the target value, and the line is lined up. The flow rate of the diluted air injected inside is derived. There is a technique described in Patent Document 2 as a technique for adjusting the flow rate of diluted air injected into the line by feedback control of the oxygen concentration inside the line. In Patent Document 2, the flow rate of nitrogen gas injected into the line is adjusted so that the deviation of the measured value of the oxygen concentration of the exhaust gas from the target value approaches 0 (zero) at the time of heat-up, and when the heat-up is completed, the exhaust gas is exhausted. After the measured value of oxygen concentration in the exhaust gas becomes less than the predetermined value below the target value, the flow rate of the diluted air injected into the line so that the deviation of the measured value of the oxygen concentration of the exhaust gas from the target value approaches 0 (zero). I try to adjust.

Japanese Unexamined Patent Publication No. 2000-79352 Japanese Unexamined Patent Publication No. 2014-74570

By the way, in general, the amount of raw material supplied to the crusher (the amount of raw material supplied) is adjusted by the operator's operation so that the inlet temperature of the crusher does not exceed the upper limit value in order to prevent carbonization and combustion of the raw material. To. The inlet temperature of the crusher tends to be high when the water content of the raw material is large or when the supply amount of the raw material is large, that is, when the flow rate of the exhaust gas from the heat gas generator is large. Therefore, by increasing the amount of coal supply so that the inlet temperature of the crusher does not exceed the upper limit as much as possible, the production capacity of the negative pressure type / exhaust gas circulation system crushing plant will not decrease. It is desired to.

However, for example, when the supply amount of the raw material is sharply reduced, especially when the inlet temperature of the crusher is high, the oxygen concentration inside the line rises sharply. In such a case, there is a possibility that the flow rate of the diluted air cannot sufficiently follow the fluctuation of the supply amount of the raw material and the increase in the oxygen concentration inside the line cannot be suppressed only by the feedback control as described above. In such a case, depending on the operating conditions such as the water content of the raw material and the outlet temperature of the crusher, the oxygen concentration inside the line may exceed the oxygen concentration controlled to prevent the occurrence of dust explosion, and the operation may be stopped urgently. There is a risk that it must be done. In order to avoid such a situation, if the supply of raw materials is not reduced sharply (in other words, the supply of raw materials is increased to prevent operation), a negative pressure type / exhaust gas circulation system crushing plant Production capacity will decrease.

The present invention has been made in view of the above problems, and even if the amount of raw material supplied to the crusher fluctuates, the oxygen concentration inside the line of the negative pressure type / exhaust gas circulation system crushing plant fluctuates. The purpose is to suppress what is done.

The crushing plant oxygen concentration control device of the present invention is a hot air generator that generates hot air as exhaust gas, and a crusher that crushes raw materials and releases the crushed raw materials to the outside on the flow of the exhaust gas. A crusher in which the internal pressure is maintained at a negative pressure, and a crusher that collects the crushed raw material released from the crusher along with the flow of the exhaust gas, and the internal pressure is a negative pressure. The oxygen concentration at a predetermined position inside the path, the path through which the exhaust gas circulates through the collector, the hot air generator, the crusher, and the collector is measured. Negative pressure type exhaust gas circulation that has a measuring means and an adjusting means for adjusting the injection amount of a diluted gas, which is a gas containing oxygen, into the path, and puts the raw material into the inside of the crusher to crush the raw material. A crushing plant oxygen concentration control device that controls the oxygen concentration inside the path in the crushing plant of the system, and brings the measured value of the oxygen concentration at the predetermined position closer to the target value of the oxygen concentration at the predetermined position. The first control means that performs feedback control and derives the flow rate of the diluting gas, which is the output of the feedback control, as the feedback control amount, the supply amount of the raw material to the crusher, and the water content of the raw material. , The flow rate of air entering the inside of the crusher from the outside, the target value of oxygen concentration at the predetermined position, and the target value of the temperature inside the path at the predetermined position on the outlet side of the crusher. Calculation of heat balance, which is a plurality of calculation formulas having as variables and balances the amount of heat given to the crushing plant of the negative pressure type / exhaust gas circulation system and the amount of heat consumed in the crushing plant of the negative pressure type / exhaust gas circulation system. The sum of the flow rate of gas injected into the crushing plant of the negative pressure type / exhaust gas circulation system and the flow rate of gas generated in the crushing plant of the negative pressure type / exhaust gas circulation system, and the flow rate of the negative pressure type / exhaust gas circulation system. It is necessary to calculate the target value of oxygen concentration at the predetermined position by calculating a plurality of formulas for calculating the material balance that balances with the flow rate of the gas discharged from the crushing plant. The second control means for deriving the flow rate of the diluting gas as a feed forward control amount, and the diluting gas derived by the second control means to the flow rate of the diluting gas derived by the first control means. It is characterized by having an adding means for adding the flow rate of the above, and an instructing means for instructing the adjusting means to operate based on the added value of the flow rate of the diluted gas obtained by the adding means. It is a sign.

The crushing plant oxygen concentration control method of the present invention is a hot air generator that generates hot air as exhaust gas, and a crusher that crushes raw materials and puts the crushed raw materials on the flow of the exhaust gas and discharges them to the outside. A crusher in which the internal pressure is maintained at a negative pressure and a crusher that collects the crushed raw material released from the crusher along with the flow of the exhaust gas, and the internal pressure is a negative pressure. The gas concentration at a predetermined position inside the path and the path through which the exhaust gas circulates through the collector, the hot air generator, the crusher, and the collector are measured. Negative pressure type exhaust gas circulation that has a measuring means and an adjusting means for adjusting the injection amount of a diluting gas, which is a gas containing oxygen, into the path, and puts the raw material into the inside of the crusher to crush the raw material. A crushing plant oxygen concentration control method for controlling the oxygen concentration inside the path in a system crushing plant, in which the measured value of the oxygen concentration at the predetermined position is brought closer to the target value of the oxygen concentration at the predetermined position. The first control step of performing feedback control and deriving the flow rate of the diluting gas, which is the output of the feedback control, as the feedback control amount, the supply amount of the raw material to the crusher, and the water content of the raw material. , a flow of air entering from outside into the interior of the crusher, and the target value of the oxygen concentration in the predetermined position, and the target value of the temperature of the interior of said path at a predetermined position of the exit side of the crusher, Is a plurality of calculation formulas having the above as a variable, and is a heat balance that balances the amount of heat given to the crushing plant of the negative pressure type / exhaust gas circulation system and the amount of heat consumed in the crushing plant of the negative pressure type / exhaust gas circulation system. Calculation, the sum of the flow rate of gas injected into the crushing plant of the negative pressure type / exhaust gas circulation system and the flow rate of gas generated in the crushing plant of the negative pressure type / exhaust gas circulation system, and the negative pressure type / exhaust gas circulation system. Necessary to maintain the target value of oxygen concentration at the predetermined position by calculating multiple formulas for calculating the material balance that balances with the flow rate of gas discharged from the crushing plant. The second control step of deriving the flow rate of the diluting gas as a feed-forward control amount, and the dilution derived by the second control step to the flow rate of the diluting gas derived by the first control step. It is characterized by having an addition step of adding the gas flow rate and an adjustment step of operating the adjustment means based on the addition value of the flow rate of the diluted gas obtained by the addition step.

The program of the present invention is characterized in that a computer functions as each means of the pulverization plant oxygen concentration control device.

According to the present invention, feedback control is performed to bring the measured value of oxygen concentration at a predetermined position inside the path through which the exhaust gas circulates closer to the target value, and the flow rate of the diluted gas, which is the output of the feedback control, is used as the feedback control amount. Derived. In addition, it is necessary to calculate the heat balance and mass balance in a negative pressure type / exhaust gas circulation system crushing plant to maintain the target value of oxygen concentration at a predetermined position inside the path through which the exhaust gas circulates. The flow rate of the diluted gas is derived as the feed forward control amount. Then, the amount of the diluted gas injected into the path is adjusted based on the added value of the flow rates of these diluted gases. Therefore, unlike the case of only the feedback control, the feedforward control allows the flow rate of the diluted air to quickly follow the fluctuation of the supply amount of the raw material to the crusher. Therefore, it is possible to suppress the fluctuation of the oxygen concentration inside the line even when the supply amount of the raw material to the crusher fluctuates.

It is a figure which shows an example of the structure of the PCI plant of the negative pressure type exhaust gas circulation system. It is a figure which shows an example of the functional structure of the pulverization plant oxygen concentration control apparatus. It is a figure which conceptually shows an example of the relationship between the flow rate of diluted air and the amount of coal supply. It is a figure which shows an example of the structure of the conversion part. It is a flowchart explaining an example of the operation of the pulverization plant oxygen concentration control apparatus when controlling the oxygen concentration in a line. It is a figure which shows the relationship between the amount of coal supply and time in an Example. It is a figure which shows the result of the comparative example. It is a figure which shows the result of the invention example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, the negative pressure type exhaust gas circulation system crushing plant crushes coal in order to inject pulverized coal into the blast furnace (PCI; Pulverized Coal Injection). A case will be described as an example.

[First Embodiment]
First, the first embodiment will be described.
(Negative pressure type / exhaust gas circulation system PCI plant configuration)
FIG. 1 is a diagram showing an example of the configuration of a negative pressure type exhaust gas circulation system PCI plant. In FIG. 1, the solid line connecting each component shows the piping, and the broken line shows the signal transmission path. In addition, the arrow line indicates the traveling direction of gas or coal in the pipe. Since the configuration of a negative pressure type / exhaust gas circulation system PCI plant can be realized by a known technique such as the technique described in Patent Document 1, each configuration will be briefly described here and detailed description will be omitted. To do.

In FIG. 1, the hot gas generator (HGG) 101 has a burner, and receives fuel gas and combustion air (air) as inputs to the burner to control the air-fuel ratio of the burner and generate exhaust gas (hot air). The oxygen concentration of the exhaust gas is approximately 0 (zero)%. In this embodiment, BFG (Blast Furnace Gas) is used as the fuel gas. The combustion air is sent to the heat gas generator 101 by the combustion air fan 102.

The bunker 103 stores coal as a raw material.
The coal feeder 104 has a chain conveyor, and the coal stored in the bunker 103 is cut out by the chain conveyor and put into the mill 105.
The mill 105 is a crusher that crushes the coal input from the coal feeder 104. By allowing the pressure at the entry side position of the mill 105 to be maintained at a negative pressure, the pressure inside the mill 105 is maintained at a negative pressure. The mill 105 has, for example, a roll mill 105a and a crushing table 105b. The coal charged from the upper part of the mill 105 is supplied between the roll mill 105a and the crushing table 105b. Coal is crushed and crushed by rotating the roll mill 105a while pressing it against the rotating crushing table 105b. The crushed coal is supplied to the upper part of the mill 105 along the flow of the exhaust gas supplied from the heat gas generator 101, classified by the classifier, and then discharged to the outside.

At this time, by supplying the seal air from the seal air fan 106 to the gap inside the mill 105 (bearing portion of the crushing table 105b), the pulverized coal that is about to be discharged to the outside through the gap is discharged from the heat gas generator 101. Push back into the flow of supplied exhaust gas. The flow rate of the seal air is determined so that the pressure inside the mill 105 is lower than the pressure of the seal air. In this way, the pulverized coal enters the bearing portion of the crushing table 105b, and as a result, poor lubrication of the bearing portion of the crushing table 105b occurs and the seal air is discharged to the outside from the bearing portion of the crushing table 105b. This is to prevent things from happening.
In the following description, "crushed coal released from the mill 105 to the outside" will be referred to as "pulverized coal" as necessary.

The bag filter 107 is a filtration type collector that collects pulverized coal released from the mill 105 using a filter cloth. Similar to the mill 105, the pressure inside the bag filter 107 is also maintained at a negative pressure. Foreign matter other than pulverized coal may be collected by the bag filter 107. The foreign matter removing device 108 is for removing the foreign matter. After the foreign matter is removed by the foreign matter removing device 108 in this way, the pulverized coal is stored in the reservoir tank 109. The pulverized coal stored in the reservoir tank 109 is blown into the inside of the blast furnace from the tuyere of the blast furnace (the pulverized coal is blown).

The bag outlet O ₂ concentration meter 110 measures the oxygen concentration of the exhaust gas in the pipe at the position on the outlet side of the bag filter 107. In the present embodiment, the measured value of the oxygen concentration of the exhaust gas in the pipe becomes the measured value of the oxygen concentration inside the line.
The Venturi tube 111 measures the flow rate of the exhaust gas that has passed through the bag filter 107.
The damper 112 adjusts the flow rate of the exhaust gas that has passed through the bag filter 107.
The circulation fan 113 boosts the exhaust gas so that the exhaust gas that has passed through the damper 112 can be circulated to the heat gas generator 101.
A part of the exhaust gas boosted by the circulation fan 113 is released into the atmosphere through the chimney 114. The dissipative pressure regulating valve 115 is for adjusting the pressure of the exhaust gas released into the atmosphere in this way. In the following description, the exhaust gas released into the atmosphere through the chimney 114 will be referred to as "emission gas" as necessary.

The circulation system pressure regulating valve 116 is for adjusting the pressure of the exhaust gas boosted by the circulation fan 113 and circulated to the heat gas generator 101 without being released into the atmosphere through the chimney 114. .. In this way, the exhaust gas generated by the heat gas generator 101 is supplied to the heat gas generator 101 again as a circulating gas, and the heat gas generator 101, the mill 105, the bag filter 107, the venturi pipe 111, the damper 112, and the circulation. It circulates through the paths of the fan 113, the circulation system pressure regulating valve 116, and the heat gas generator 101.

In the present embodiment, the oxygen concentration of the circulating gas in the PCI plant of the above negative pressure type / exhaust gas circulation system is adjusted. First, an example of a hardware configuration for adjusting the oxygen concentration of the circulating gas will be described.
In the present embodiment, air in the atmosphere is supplied as diluted air to a negative pressure type exhaust gas circulation system PCI plant. The orifice flow meter 117 measures the flow rate of this diluted air. The air flow rate adjusting valve 118 is for adjusting the flow rate of the diluted air supplied to the PCI plant of the negative pressure type / exhaust gas circulation system. The dilution air fan 119 boosts the diluted air whose flow rate has been adjusted by the air flow rate adjusting valve 118, and pushes the diluted air into the piping on the inlet side of the heat gas generator 101. Thereby, the oxygen concentration of the circulating gas can be adjusted.
The crushing plant oxygen concentration controller 200 inputs the oxygen concentration of the exhaust gas measured by the bug outlet O ₂ concentration meter 110, and the air flow rate so that the deviation of the measured value of the oxygen concentration from the target value approaches 0 (zero). The valve opening of the adjusting valve 118 is set to adjust the oxygen concentration of the circulating gas.

(Functional configuration of crushing plant oxygen concentration control device 200)
FIG. 2 is a diagram showing an example of a functional configuration of the pulverization plant oxygen concentration control device 200. As described above, each part shown in FIG. 2 can be realized by using, for example, a programmable logic controller (PLC) or a computer device including a CPU, ROM, RAM, HDD and various interfaces.

<O ₂ concentration target value storage unit 201>
The O ₂ concentration target value storage unit 201 stores the target value of the oxygen concentration of the exhaust gas at the position where the oxygen concentration of the exhaust gas is measured by the bug outlet O ₂ concentration meter 110. The target value of the oxygen concentration of the exhaust gas is set by the operator. In the negative pressure type exhaust gas circulation system PCI plant of the present embodiment, the oxygen concentration of the exhaust gas measured by the bug outlet O ₂ concentration meter 110 needs to be less than 12 [%] from the viewpoint of preventing a dust explosion. Therefore, in the present embodiment, the target value of the oxygen concentration of the exhaust gas at the position where the oxygen concentration of the exhaust gas is measured by the bug outlet O ₂ concentration meter 110 is set to 10 [%]. As described above, in the present embodiment, the unit of the oxygen concentration of the exhaust gas is [%].

<O ₂ Concentration Deviation Derivation Unit 202>
The O ₂ concentration deviation derivation unit 202 obtains the measured value of the oxygen concentration of the exhaust gas measured by the bug outlet O ₂ concentration meter 110 from the target value of the oxygen concentration of the exhaust gas stored in the O ₂ concentration target value storage unit 201. By subtracting, the deviation e of the measured value of the oxygen concentration of the exhaust gas with respect to the target value is derived.

<PID control unit 203>
The PID control unit 203 performs proportional operation, integration operation, and differential operation by inputting "deviation e from the measured value of the oxygen concentration of the exhaust gas with respect to the target value" derived by the O ₂ concentration deviation derivation unit 202, and operates the amount. It is a controller that repeatedly derives the oxygen concentration of the exhaust gas to bring the oxygen concentration of the exhaust gas closer to the target value (PID control). Then, the PID control unit 203 derives the flow rate of the diluted air that becomes the oxygen concentration of the exhaust gas derived as the operation amount as the feedback control amount (feedback control output).

<Mill outlet temperature target value storage unit 204>
The target value of the mill outlet temperature, which is the temperature (of pulverized coal) in the pipe at a predetermined position on the outlet side of the mill 105, is stored. The target value of the mill outlet temperature is set by the operator.

<FF control unit 205>
The FF control unit 205 is a controller that derives the flow rate of diluted air as a feedforward control amount (output of feedforward control) added to the flow rate of diluted air derived by the PID control unit 203.
In the present embodiment, the FF control unit 205 has a water content of coal as a raw material, a water content of a product (pulverized coal) obtained by crushing and drying the raw material, a seal air flow rate, an approach air flow rate, and a mill outlet temperature. By inputting the target value of the oxygen concentration of the exhaust gas, the target value of the oxygen concentration of the exhaust gas, the amount of coal supply, etc., the calculation of the material / heat balance model, which is a calculation formula based on the mass balance / heat balance in the PCI plant of the negative pressure type / exhaust gas circulation system. By doing so, the flow rate of diluted air required to maintain the oxygen concentration in the pipe at the target value is derived.

Here, the substance / heat balance model will be described.
[Material / heat balance model]
The material / heat balance model uses the flow rate of diluted air required to maintain the oxygen concentration in the piping at the target value as the balance of heat balance and gas balance in the negative pressure type / exhaust gas circulation system PCI plant. It is derived by performing a calculation that takes.

[[Assumptions for building a material / heat balance model]]
In this embodiment, a substance / heat balance model is constructed under the following conditions.
(A) Regarding both the balance of heat balance and the balance of gas balance, the unsteady balance is ignored and only the steady balance is expressed.
(B) The amount of heat required for the phase change of water contained in the raw material coal is calculated from the latent heat required to generate the amount of water vapor generated from coal.
(C) For the sake of simplicity, the flow rate of the exhaust gas generated by the combustion of the fuel gas (BFG) is the sum of the flow rate of the fuel gas (BFG) and the flow rate of the combustion air.
(D) The temperature raising effect of the circulating fan 113 is simplified to contribute only to the circulating gas, and it is assumed that the temperature of the emitted gas is the same as the mill outlet temperature.
(E) It is assumed that the temperature inside the system of the negative pressure type exhaust gas circulation system PCI plant is the same as the mill outlet temperature.
(F) The fuel gas (BFG) shall be completely combusted, and excess combustion air shall remain as it is.
(G) The bag outlet oxygen concentration (the concentration of oxygen gas in the pipe at the position on the outlet side of the bag filter 107) shall be maintained at a constant value by controlling the flow rate of the diluted air.
(H) The flow rate of the bag outlet exhaust gas (the flow rate of the exhaust gas in the pipe at the position on the outlet side of the bag filter 107) shall be maintained at a constant amount by the flow rate control.

[[Model parameters to be input to the material / heat balance model]]
In the substance / heat balance model of the present embodiment, the following operating conditions (target values) are given as input values as model parameters.
-Amount of coal supply-Target value of temperature of pulverized coal (mill outlet temperature) -Bug outlet exhaust gas flow rate (flow rate of exhaust gas in the pipe at a predetermined position on the outlet side of the mill 105)
-Target value of oxygen concentration in piping These model parameters (operating conditions) are changed to arbitrary values according to the operation.

In addition, the following environmental conditions are given as input values as model parameters.
・ Moisture content in coal (coal moisture content)
・ Moisture content in pulverized coal (moisture content of product)
・ Temperature (diluted air, coal, injection gas)
・ Specific heat (water, gas, coal)
・ Latent heat of water ・ Gas calorie of fuel ・ Theoretical amount of air in the burner ・ Excessive amount of air in the burner ・ Flow rate of ingress air ・ Flow rate of seal air ・ Temperature rise of circulating gas due to adiabatic compression in the circulation fan 113

In this embodiment, these model parameters (environmental conditions) are semi-fixed values and are changed as necessary. As the environmental conditions, it is preferable to adopt the average value in the negative pressure type exhaust gas circulation system PCI plant to which the substance / heat balance model is applied. The water content and temperature can be obtained in advance by sampling, for example. Further, since the theoretical air amount of the burner changes depending on the composition of the fuel gas, it is set based on the composition of the fuel gas. Increasing the value of the excess air amount of the burner can prevent poor combustion, so the excess air amount of the burner is appropriately set from this viewpoint.

[[Heat balance model]]
In the present embodiment, a formula for formulating that the amount of heat given to the PCI plant of the negative pressure type / exhaust gas circulation system and the amount of heat consumed are equal is expressed as a heat balance model. The amount of heat given to and the amount of heat consumed in a negative pressure type exhaust gas circulation system PCI plant will be described.
(1) Formula of calorie required for heating coal The calorie ΔQ _COAL [kcal] required for heating coal to the temperature of the product is expressed by the following formula (1).
ΔQ _COAL = Specific heat of raw material x Coal supply amount x 1000 x (Product temperature-Raw material temperature) ... (1)
As described above, the amount of coal supplied [ton / hr] and the temperature of the product are given as operating conditions, and the specific heat [kcal / kg · ° C] of the raw material and the temperature [° C] of the raw material are environmental conditions. It is given.

(2) Formula of the amount of heat required to heat water The amount of heat ΔQ (sensible heat) [kcal] required to heat the water contained in coal to the temperature of the product is expressed by the following formula (2).
ΔQ (sensible heat) = specific heat of water x WM x (product temperature-raw material temperature) ... (2)
As described above, the specific heat [kcal / kg · ° C.] of water is given as an environmental condition.
Further, in the formula (2), WM is the weight [kg / hr] of water contained in coal per unit time, and is represented by the following formula (2a).
WM = Coal supply amount x 1000 x Coal water content / (100-Coal water content) ... (2a)
As described above, the amount of coal supplied [ton / hr] is given as an operating condition, and the amount of water [mass%] of coal is given as an environmental condition.

(3) Formula of calorie required for evaporation of water The calorie ΔQ (latent heat) [kcal] required for water contained in coal to evaporate is expressed by the following equation (3).
ΔQ (latent heat) = latent heat of water x WV ・ ・ ・ (3)
As mentioned above, the latent heat [kcal / kg] of water is an environmental condition.
Further, in the formula (3), WV is the weight [kg / hr] of water existing as water vapor per unit time, and is represented by the following formula (3a).
WV = Coal supply amount x 1000 x {Coal water content / (100-Coal water content) -Product water content / (100-Product water content)} ... (3a)
As described above, the coal supply amount [ton / hr] is given as an operating condition, and the water content [mass%] of the coal and the water content [mass%] of the product are given as environmental conditions. is there.

(4) Formula of calorie obtained by burner combustion The calorie ΔQ _HGG [kcal] generated by combustion with fuel gas is represented by the following formula (4).
ΔQ _HGG = fuel gas calorie x fuel gas flow rate ... (4)
As mentioned above, the gas calorie [kcal / Nm ³ ] of the fuel is given as an environmental condition. The flow rate of fuel gas [Nm ³ / hr] is a determinant.

(5) Equation of flow rate of combustion air consumed by burner combustion The flow rate of combustion air [Nm ³ / hr] consumed by combustion is expressed by the following equation (5).
Combustion air flow rate = fuel gas flow rate x theoretical air volume x excess air volume ... (5)
As described above, the theoretical air volume [-] and the excess air volume [-] are given as environmental conditions. The flow rate of combustion air [Nm ³ / hr] and the flow rate of fuel gas [Nm ³ / hr] are determinants.

(6) Formula of the flow rate of exhaust gas generated by burner combustion The flow rate of exhaust gas generated by combustion of fuel gas (burner combustion exhaust gas flow rate) [Nm ³ / hr] is expressed by the following formula (6).
Burner combustion exhaust gas flow rate = fuel gas flow rate + combustion air flow rate ... (6)
Actually, the burner combustion exhaust gas flow rate is smaller than the sum of the fuel gas flow rate and the combustion air flow rate, but even if the burner combustion exhaust gas flow rate is expressed as the sum of these, a large error does not occur. Therefore, in the present embodiment, the flow rate of the burner combustion exhaust gas is approximated by the sum of the flow rate of the fuel gas and the flow rate of the combustion air. The flow rate of combustion air [Nm ³ / hr] and the flow rate of fuel gas [Nm ³ / hr] are given as determinants.

(7) Equation of temperature rise due to adiabatic compression in the circulation fan The amount of heat ΔQ _FAN [kcal] generated due to the adiabatic compression in the circulation fan 113 is expressed by the following equation (7).
ΔQ _FAN = Flow rate of circulating gas × ΔT × Specific heat of gas ・ ・ ・ (7)
As described above, the specific heat [kcal / kg · ° C.] of the gas is given as an environmental condition. ΔT is the temperature rise [° C.] of the circulating gas due to the adiabatic compression in the circulating fan 113, and is given as an environmental condition as described above. The flow rate of the circulating gas [Nm ³ / hr] is expressed by the following equation (7a).

Circulating gas flow rate = Bug outlet exhaust gas flow rate-Dissipated gas flow rate ... (7a)
As described above, the bus outlet exhaust gas flow rate [Nm ³ / hr] is given as an operating condition. The flow rate of the emitted gas [Nm ³ / hr] is expressed by the following equation (7b).
Flow rate of emitted gas = Σ gas flow rate (i) + WV × 22.4 / 18 ・ ・ ・ (7b)
In the equation (7b), the flow rate (i) of the Σ gas is represented by the following equation (7c).
Σ gas flow rate (i) = fuel gas flow rate + combustion air flow rate + diluted air flow rate + approach air flow rate + seal air flow rate ... (7c)
As described above, the flow rate of the fuel gas [Nm ³ / hr] and the flow rate of the combustion air [Nm ³ / hr] are given as determinants. The flow rate of the approach air [Nm ³ / hr] and the flow rate of the seal air [Nm ³ / hr] are given as environmental conditions. WV is the weight [kg / hr] of water existing as water vapor per unit time, and is represented by the formula (3a). The flow rate of diluted air [Nm ³ / hr] is a determinant. In addition, "22.4" of the formula (7b) is a standard volume (molar volume) [liter / mol], and "18" is the molecular weight of water [gram / mol]. Therefore, "22.4 / 18" in Eq. (7b) is a coefficient for converting weight into volume.

When the amount of heat given to the negative pressure type / exhaust gas circulation system PCI plant becomes equal to the amount of heat consumed, the heat balance in the negative pressure type / exhaust gas circulation system PCI plant can be balanced. Therefore, the above equations (1) to (7) ), The following equation (8) is obtained as a heat balance model.
ΣΔQ _GAS (i) ＋ ΔQ _COAL ＋ ΔQ (sensible heat) ＋ ΔQ (latent heat) ＝ ΔQ _HGG ＋ ΔQ _FAN・ ・ ・ (8)
In equation (8), the left side is the total amount of heat consumed by the negative pressure type / exhaust gas circulation system PCI plant, and the right side is the total amount of heat given to the negative pressure type / exhaust gas circulation system PCI plant.

Further, ΣΔQ _GAS (i) is expressed by the following equation (8a).
ΣΔQ _GAS (i) = Σ [specific heat of gas (i) x flow rate of gas (i) x (product temperature-injection temperature of gas (i))] ... (8a)
The gas (i) is a fuel gas, combustion air, diluted air, approach air, and seal air, and the integrated value of the values in [] of the equation (8a) for these gases is derived by the equation (8a).

As described above, the temperature of the product is given as an operating condition, and the specific heat of the gas and the injection temperature are given as environmental conditions. Further, the flow rate of fuel gas [Nm ³ / hr], the flow rate of combustion air [Nm ³ / hr], and the flow rate of diluted air [Nm ³ / hr] are determinants. The flow rate of fuel gas [Nm ³ / hr] and the flow rate of combustion air [Nm ³ / hr] are expressed by equations (5) and (6). Further, the flow rate of the approach air [Nm ³ / hr] and the flow rate of the seal air [Nm ³ / hr] are given as environmental conditions.

[[Mass balance model]]
The gas injected into the negative pressure type / exhaust gas circulation system PCI plant and the gas generated in the negative pressure type / exhaust gas circulation system PCI plant are sufficiently mixed, and the amount is the same as the sum of the injection amount and the generated amount of these gases. A formula for releasing gas into the atmosphere through the chimney 114 is expressed as a mass balance model. Specifically, the mass balance model is expressed by the following equation (9).
Oxygen concentration in the pipe = [(flow rate of seal air + flow rate of approach air + flow rate of diluted air + flow rate of combustion air x 0.1) / flow rate of radiated gas] x 21 ... (9)
As described above, the flow rate of diluted air [Nm ³ / hr] and the flow rate of combustion air [Nm ³ / hr] are determinants. The oxygen concentration [volume%] in the pipe is given as an operating condition, and the inflow air flow rate [Nm ³ / hr] and the seal air flow rate [Nm ³ / hr] are given as environmental conditions. Is. Further, the flow rate of the emitted gas [Nm ³ / hr] is expressed by the equations (7b) and (7c). On the right side of the equation (9), "combustion air flow rate x 0.1" is the flow rate of excess air due to the combustion reaction.

The FF control unit 205 performs calculations that satisfy all of the above equations (1) to (9) to derive determinants (fuel gas flow rate, combustion air flow rate, and diluted air flow rate). Specifically, the derivation of these decision variables can be realized, for example, by performing the iterative calculation of Eqs. (8) and (9) until a predetermined convergence condition is satisfied. That is, the flow rate of the fuel gas and the flow rate of the combustion air derived from the equations (1) to (8) are given to the equation (9) to derive the flow rate of the diluted air, and the derived flow rate of the diluted air is (7c). Given in the equation, the flow rate of the fuel gas and the flow rate of the combustion air are derived by the equations (1) to (8) until the solutions of each determinant converge. In this way, the FF control unit 205 derives the flow rate of the diluted air, which is one of the determinants. If the flow rate of the diluted air is kept constant at the value derived in this way, the oxygen concentration in the pipe will ideally converge to the target value.

Here, when the equation (9) is modified, the flow rate of the diluted air is expressed as the following equation (10).
Flow rate of diluted air = [Target value of oxygen concentration in piping x (flow rate of seal air + flow rate of ingress air + flow rate of fuel gas + flow rate of combustion air + flow rate of water vapor) -21 x (flow rate of seal air + flow rate of ingress air) Flow rate + 0.1 x flow rate of combustion air)] / (21-Target value of oxygen concentration in the pipe) ・ ・ ・ (10)
The flow rate of water vapor is represented by WV × 22.4 / 18. The flow rate of the diluted air is derived from the equation (10).

In the present embodiment, the initial value of the FF control amount (that is, the value of the FF control amount at the start of coal feeding) is set to 0 (zero).
Further, in the present embodiment, the feedforward control is expressed by a speed type, and is operated only in response to a change in the amount of coal supply.
Therefore, the feedforward control amount (FF control amount) is expressed by the following equation (11), and the ΔFF control amount is expressed by the following equation (12).

FF control amount = f (coal supply amount, target value of oxygen concentration in piping, target value of mill outlet temperature, water content of coal) ... (11)
ΔFF control amount = FF control amount-FF control amount_previous value ... (12)
In equation (11), f represents a function whose variables are the amount of coal supplied, the target value of oxygen concentration in the pipe, the target value of the mill outlet temperature, and the water content of coal. Further, in the equations (11) and (12), the FF control amount is the flow rate of the diluted air derived as described above, and the FF control amount_previous value is the previous value of the FF control amount. ..

Here, if the ΔFF control amount is defined by the following equation (13), the FF control amount is described by the velocity type as in the following equation (14).
ΔFF control amount = (∂FF control amount / ∂ coal supply amount) × Δ coal supply amount ・ ・ ・ (13)
FF control amount = FF control amount_previous value + ΔFF control amount ... (14)
In equation (13), (∂FF control amount / ∂ coal supply amount) is the amount of coal supply when the target value of oxygen concentration in the pipe, the target value of mill outlet temperature, and the water content of coal are fixed. This is the amount of change in the FF control amount with respect to the amount of change. As described above, in the present embodiment, if there is no change in the coal supply amount, the ΔFF control amount becomes 0 (zero), and the feedback control amount (FF control amount) remains at the previous value.

FIG. 3 is a diagram conceptually showing an example of the relationship between the flow rate of diluted air and the amount of coal supplied. In the example shown in FIG. 3, it is shown that feedforward control is performed at the portion indicated by hatching. That is, in the example shown in FIG. 3, when the minimum coal supply amount at the start of crushing is 30 [ton / hr], the feedforward control amount (FF control amount) is 0 (zero), and then the coal supply amount. It is shown that the ΔFF control amount increases as the number increases, and as a result, the feedforward control amount (FF control amount) increases. Although FIG. 3 shows an example in which the relationship between the flow rate of diluted air and the amount of coal supplied is directly proportional, the relationship between the flow rate of diluted air and the amount of coal supplied is not limited to direct proportion.

The FF control unit 205 derives (∂FF control amount / ∂ coal supply amount) by deriving the relationship between the flow rate of the diluted air derived as described above and the coal supply amount. The Δ coal supply amount is the amount of change in the coal supply amount for each control cycle. The FF control unit 205 derives the ΔFF control amount in this way, and adds the derived ΔFF control amount to the previous value (FF control amount_previous value) of the FF control amount to derive the feedforward control amount. To do.

<Addition part 206>
The adding unit 206 adds the flow rate of the diluted air derived as the feedforward control amount by the FF control unit 205 to the flow rate of the diluted air derived as the feedback control amount by the PID control unit 203.

<Conversion unit 207>
The conversion unit 207 converts the added value of the flow rate of the diluted air obtained by the addition unit 206 into the opening degree of the air flow rate adjusting valve 118.
FIG. 4 is a diagram showing an example of the configuration of the conversion unit 207. FIG. 4A is a diagram showing a first example of the configuration of the conversion unit 207, and FIG. 4B is a diagram showing a second example of the configuration of the conversion unit 207. In this embodiment, any of the conversion units 207 of FIGS. 4 (a) and 4 (b) may be adopted.

In the example shown in FIG. 4A, the conversion unit 207 has a flow rate-opening relationship storage unit 207a, a flow rate-opening conversion unit 207b, and an instruction unit 207c.
The flow rate-opening relationship storage unit 207a stores information indicating the relationship between the flow rate of the diluted air and the opening degree of the air flow rate adjusting valve 118. The information indicating the relationship between the flow rate of the diluted air and the opening degree of the air flow rate adjusting valve 118 may be information indicating these relational expressions or a table for storing these in association with each other. The relationship between the flow rate of diluted air and the opening degree of the air flow rate adjusting valve 118 can be obtained by investigating in advance the operation results of a negative pressure type exhaust gas circulation system PCI plant.

The flow rate-opening conversion unit 207b stores the opening degree of the air flow rate adjusting valve 118 corresponding to the flow rate of the diluted air derived by the addition unit 206 in the flow rate-opening relationship storage unit 207a of the diluted air. It is derived from the relationship between the flow rate and the opening degree of the air flow rate adjusting valve 118.
The indicator 207c operates the air flow rate adjusting valve 118 or the air flow rate so that the opening degree of the air flow rate adjusting valve 118 becomes the value derived by the flow rate-opening conversion unit 207b. Instruct the drive unit of the regulating valve 118.

On the other hand, in the example shown in FIG. 4B, the conversion unit 207 includes a dilution air flow rate deviation derivation unit 207d, a PID control unit 207e, and an instruction unit 207f.
The diluted air flow rate deviation derivation unit 207d subtracts the flow rate of the diluted air measured by the orifice flow meter 117 from the flow rate of the diluted air derived by the addition unit 206, and predicts the measured value of the flow rate of the diluted air ( The deviation e with respect to the addition value of the flow rate of the diluted air obtained by the addition unit 206) is derived.

The PID control unit 207e performs proportional operation, integration operation, and differential operation by inputting "deviation e from the predicted value of the measured value of the flow rate of diluted air" derived by the dilution air flow rate deviation derivation unit 207d, and operates the manipulated variable. The flow rate of the diluted air is repeatedly derived as a method to bring the flow rate of the diluted air closer to the predicted value (PID control). Then, the PID control unit 207e derives the opening degree of the air flow rate adjusting valve 118 so as to be the flow rate of the diluted air derived as the operation amount.

The indicator unit 207f operates the air flow rate adjusting valve 118 so that the opening degree of the air flow rate adjusting valve 118 becomes the value derived by the PID control unit 207e, so that the air flow rate adjusting valve 118 or the air flow rate adjusting valve 118 is operated. Instruct the drive unit of.
When the configuration shown in FIG. 4B is adopted, cascade control is used.

(flowchart)
Next, an example of the operation of the pulverization plant oxygen concentration control device 200 when controlling the oxygen concentration inside the line will be described with reference to the flowchart of FIG.
First, in step S501, the O ₂ concentration deviation derivation unit 202 derives the deviation e of the measured value of the oxygen concentration of the exhaust gas with respect to the target value.
Next, in step S502, the PID control unit 203 performs PID control by inputting the deviation e of the measured value of the oxygen concentration of the exhaust gas from the target value, derives the oxygen concentration of the exhaust gas as the manipulated variable, and derives the oxygen concentration of the derived exhaust gas. The flow rate of diluted air that reaches the oxygen concentration is derived as the feedback control amount.

Next, in step S503, the FF control unit 205 derives the flow rate of the diluted air as a feedforward control amount by calculating the material / heat balance model. As described above, in the present embodiment, the feedforward control amount is derived by performing the speed type control.
Next, in step S504, the addition unit 206 adds the flow rate of the diluted air derived as the feedforward control amount in step S503 to the flow rate of the diluted air derived as the feedback control amount in step S502.

Next, in step S505, the conversion unit 207 converts the flow rate of the diluted air derived in step S504 into the opening degree of the air flow rate adjusting valve 118.
Next, in step S506, the conversion unit 207 tells the air flow rate adjusting valve 118 or the air to operate the air flow rate adjusting valve 118 so that the opening degree of the air flow rate adjusting valve 118 becomes the value derived in step S505. Instruct the drive device of the flow control valve 118.
Next, in step S507, the pulverization plant oxygen concentration control device 200 determines whether or not pulverization is completed. This determination can be made based on, for example, information transmitted from a higher-level computer that manages the operation of a negative pressure type exhaust gas circulation system PCI plant.

As a result of this determination, when the pulverization is finished, the process according to the flowchart of FIG. 5 is finished. On the other hand, if the pulverization is not completed, the process returns to step S501, and steps S501 to S507 are repeated until it is determined that the pulverization is completed.

(Summary)
As described above, in the present embodiment, feedback control is performed to bring the measured value of the oxygen concentration of the exhaust gas closer to the target value, and the flow rate of the diluted air, which is the output of the feedback control, is derived as the feedback control amount. In addition, the calculation of the heat balance that balances the amount of heat given to the negative pressure type / exhaust gas circulation system PCI plant and the amount of heat consumed by the negative pressure type / exhaust gas circulation system PCI plant, and the negative pressure type / exhaust gas circulation system PCI plant. Balance the sum of the flow rate of gas injected into and the flow rate of gas generated in the negative pressure type / exhaust gas circulation system PCI plant and the flow rate of gas discharged from the negative pressure type / exhaust gas circulation system PCI plant. By calculating the material balance (calculating the material / heat balance model), the flow rate of diluted air required to maintain the target value of the oxygen concentration of the exhaust gas is derived as the feed forward control amount.

Then, the flow rate of the diluted air derived as the feedforward control amount is added to the flow rate of the diluted air derived as the feedback control amount, and the added value is converted into the opening degree of the air flow rate adjusting valve 118. The air flow rate adjusting valve 118 is operated so that the opening degree obtained in this manner is obtained.
Therefore, as compared with the case where only the feedback control is performed, the flow rate of the diluted air can be made to follow the fluctuation of the coal supply amount even when the coal supply amount fluctuates. Therefore, even if the supply amount of the raw material (coal) to the mill 105 fluctuates, it is possible to suppress the fluctuation of the oxygen concentration inside the line. As a result, for example, it is possible to prevent the oxygen concentration inside the line from exceeding the control value determined from the viewpoint of preventing a dust explosion due to a sudden decrease in the amount of coal supplied. As a result, it is not necessary to reduce the coal supply amount more than necessary so that the oxygen concentration inside the line does not exceed the control value. Therefore, the amount of coal supplied can be increased until the temperature inside the pipe at a predetermined position on the inlet side of the mill 105 becomes close to the upper limit value, and the production capacity of the negative pressure type exhaust gas circulation system PCI plant. Can be improved.

(Modification example)
In the present embodiment, a case where the pulverization plant oxygen concentration control device 200 is applied to a negative pressure type exhaust gas circulation system PCI plant has been described as an example. However, the crushing plant oxygen concentration control device 200 can also be applied to a crushing plant of a negative pressure type / exhaust gas circulation system other than a PCI plant of a negative pressure type / exhaust gas circulation system. For example, the crushing plant oxygen concentration control device 200 can also be applied to a crushing plant of a negative pressure type exhaust gas circulation system for producing cement.

Further, in the present embodiment, a case where PID control is performed as feedback control for bringing the measured value of the oxygen concentration of the exhaust gas closer to the target value has been described as an example. However, any control may be performed as long as it is feedback control that brings the measured value of the oxygen concentration of the exhaust gas closer to the target value. For example, control to perform at least one operation including proportional operation among proportional operation, integral operation, and differential operation may be performed (for example, P control or PI control may be performed instead of PID control. May be).

[Second Embodiment]
Next, the second embodiment will be described.
In the first embodiment, the case where the water content of coal as a raw material is a semi-fixed value as an environmental condition has been described as an example. As mentioned above, the oxygen concentration inside the line fluctuates greatly depending on the water content of coal. Therefore, in the present embodiment, the accuracy of the flow rate of the diluted air derived as the feedforward control amount is further improved by estimating the water content of the coal. As described above, the method of obtaining the water content of coal is mainly different between the first embodiment and the present embodiment. Therefore, in the description of the present embodiment, detailed description of the same parts as those of the first embodiment will be omitted by adding the same reference numerals as those given in FIGS. 1 to 5.

In equation (9), all except the flow rate of seal air and the flow rate of approach air can be measured. Therefore, in the present embodiment, the sum of the flow rate of the seal air and the flow rate of the approach air is treated as the flow rate of the unobservable air, and the flow rate of the seal air and the flow rate of the approach air are treated as a collective flow rate.
Then, the equation (9) becomes the following equation (15).
Oxygen concentration in the pipe = [(flow rate of unobservable air + flow rate of diluted air + flow rate of combustion air x 0.1) / flow rate of emitted gas] x 21 ... (15)
The flow rate of unobservable air is derived from Eq. (15).

Next, when equations (7b) and (7c) are rewritten using the flow rate of unobservable air, the flow rate of the emitted gas is expressed as the following equation (16).
Dissipated gas flow rate = Fuel gas flow rate + Combustion air flow rate + Diluted air flow rate + Unobservable air flow rate + WV x 22.4 / 18 ... (16)
As described above, WV × 22.4 / 18 in the equation (16) is the flow rate of water vapor. From equation (16), the flow rate of this water vapor (WV: weight of water existing as water vapor per unit time) is derived.

Here, the water content of the product is empirically determined (for example, 1.5 [%]). Therefore, when the flow rate of water vapor (WV × 22.4 / 18) is derived in this way, the water content of coal is derived from the equation (3a).

Therefore, in the present embodiment, for example, the oxygen concentration in the pipe is measured by the bug outlet O ₂ concentration meter 110, the flow rate of the diluted air is measured by the orifice flow meter 117, and the fuel gas sent to the heat gas generator 101 is measured. The flow rate is measured by an orifice flow meter (not shown), the flow rate of combustion air sent to the hot gas generator 101 is measured by an orifice flow meter (not shown), and the flow rate of the emitted gas is measured from the chimney 114 toward the atmosphere. Measure the flow rate with an orifice flow meter (not shown). Then, the FF control unit 205 inputs these measured values and calculates the equations (15), (16), and (3a) to derive the water content of the coal, and the derived coal is derived. Instead of the water content of coal, which was treated as a semi-fixed value in the first embodiment, the flow rate of the diluted air as the feed forward control amount was used as described in the first embodiment. Derived.

In order to reduce the influence of the time variation of the measured values when deriving the water content of coal as described above, the following is carried out in the present embodiment.
First, for the flow rate of diluted air, the flow rate of fuel gas, the flow rate of combustion air, and the flow rate of radiated gas, representative values for a predetermined time (for example, 30 minutes) are used. As the representative value, for example, an average value or a moving average value can be used. In addition to these, a representative value for a predetermined time (for example, 30 minutes) may be used for the oxygen concentration in the pipe. Therefore, the FF control unit 205 calculates these representative values, and uses the calculated representative values to calculate the equations (15), (16), and (3a) to obtain the water content of coal. Is derived.

Further, as described above, in the substance / heat balance model, both the heat balance and the gas balance are ignored, and only the steady balance is expressed. Therefore, the FF control unit 205 does not derive the water content of the coal last time during the period from the start of the coal supply until the predetermined time elapses and the period when the coal supply amount is changed. The value of the water content of the derived coal is adopted. Further, when deriving the above-mentioned representative value, the above-mentioned measured value during the period from the start of coal supply to the elapse of a predetermined time and the period during which the amount of coal supply is changed may not be used.

As described above, in the present embodiment, the water content of coal is derived (estimated) by calculating the mass balance model using the measured values. Therefore, the calculation accuracy of the substance / heat balance model can be improved. Therefore, a more accurate flow rate of the diluted air according to the water content of the coal, which changes depending on the weather and the brand of coal, can be derived as the feedforward control amount. As a result, robust feedforward control can be realized.
Also in this embodiment, various modifications described in the first embodiment can be adopted.

(Example)
Next, an embodiment will be described.
In this embodiment, in the negative pressure type exhaust gas circulation system PCI plant shown in FIG. 1, the flow rate of diluted air when crushing coal under the following operating conditions is derived. Then, it was simulated by computer simulation that the oxygen concentration inside the line was measured by the bug outlet O ₂ densitometer 110 while operating the air flow rate adjusting valve 118 so that the flow rate of the diluted air was derived.

Here, an example of the invention is a case where the flow rate of the diluted air is derived by using the pulverization plant oxygen concentration control device 200 described in the first embodiment. Further, a comparative example is a case where the flow rate of the diluted air is derived from the crushing plant oxygen concentration control device 200 described in the first embodiment by using the crushing plant oxygen concentration control device excluding the FF control unit 205 and the addition unit 206. And said. As described above, in the comparative example, only the feedback control is performed without the feedforward control.

The operating conditions are as follows.
Moisture content of coal: 8.0 [%]
Product moisture content: 1.5 [%]
Target value of mill outlet temperature: 90 [° C]
Outside temperature: 5 [℃]
Target value of oxygen concentration inside the line: 10 [%]
Fuel gas: BFG
Minimum value of coal supply: 30 [ton / hr]
Maximum amount of coal supply: 60 [ton / hr]
FIG. 6 is a diagram showing the relationship between the amount of coal supplied and time. As shown in FIG. 6, the time change of the oxygen concentration inside the line and the flow rate of the diluted air when the coal supply amount is changed from 30 [ton / hr] → 60 [ton / hr] → 30 [ton / hr]. evaluated.

FIG. 7 is a diagram showing the results of a comparative example. Specifically, FIG. 7A is a diagram showing the relationship between the oxygen concentration inside the line and time, and FIG. 7B is a diagram showing the relationship between the flow rate of diluted air and time. FIG. 8 is a diagram showing the results of the invention example. Specifically, FIG. 8A is a diagram showing the relationship between the oxygen concentration inside the line and time, and FIG. 8B is a diagram showing the relationship between the flow rate of diluted air and time.

The oxygen concentration inside the line fluctuates due to changes in the amount of coal supplied. This is because the load (burner load) of the hot gas generator 101 increases or decreases in order to maintain the mill outlet temperature at 90 [° C.], and as a result, the flow rate of the exhaust gas generated from the hot gas generator 101 (burner) and the flow rate of the exhaust gas. Corresponds to the increase and decrease of the flow rate of water vapor generated from coal.

As shown in FIG. 7B, when the flow rate of the diluted air is derived only by feedback control, the flow rate of the diluted air does not follow the fluctuation of the coal supply amount. Therefore, as shown in FIG. 7A, the oxygen concentration inside the line decreases transiently (corresponding to the increase in the amount of coal supply), or the oxygen concentration inside the line increases (the amount of coal supply decreases). Corresponds to).
When the water content of coal is larger than 8.0 [%], the flow rate of the required diluted air becomes larger, so the fluctuation range of the oxygen concentration inside the line is larger than that shown in FIG. 7 (a). Will be even larger. When the oxygen concentration inside the line exceeds the upper limit (for example, 12 [%]), the crushing facility is stopped in an emergency from the viewpoint of preventing the occurrence of a dust explosion. This means that the larger the water content of the coal, the greater the risk that the crushing facility will be shut down when the coal supply amount is changed significantly.

On the other hand, as shown in FIG. 8B, by incorporating the feedforward control described in the first embodiment, the feedforward control sets the flow rate of the diluted air to the amount of coal supplied, unlike the case of only the feedback control. Quickly follow changes. Therefore, the transient decrease in oxygen concentration inside the line (corresponding to the increase in coal supply amount) or the transient increase in oxygen concentration inside the line (corresponding to the decrease in coal supply amount) is effectively suppressed. To. In the result shown in FIG. 8A, the fluctuation range of the oxygen concentration inside the line can be suppressed to about 1/10 of the result shown in FIG. 7A. This means that the risk of an emergency shutdown of the crushing equipment can be eliminated even when the amount of coal supply is significantly changed by applying feedforward control.

The embodiment of the present invention described above can be realized by executing a program by a computer. In addition, a computer-readable recording medium on which the program is recorded and a computer program product such as the program can also be applied as an embodiment of the present invention. As the recording medium, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a non-volatile memory card, a ROM, or the like can be used.
In addition, the embodiments and examples of the present invention described above are merely examples of embodiment in carrying out the present invention, and the technical scope of the present invention is limitedly interpreted by these. It should not be done. That is, the present invention can be implemented in various forms without departing from the technical idea or its main features.

(Correspondence with claims)
<Claim 1>
The hot air generator is realized by, for example, a hot gas generator 101.
The crusher is realized, for example, by the mill 105.
The collector is realized by, for example, a bag filter 107.
The paths are, for example, in FIG. 1, a heat gas generator 101 and a mill 105, a mill 105 and a bag filter 107, a bag filter 107 and a damper 112, a damper 112 and a circulation fan 113, a circulation fan 113 and a circulation system pressure regulating valve 116, It is realized by piping connecting the circulation system pressure regulating valve 116 and the heat gas generator 101, respectively.
The measuring means is realized by, for example, a bug outlet O ₂ densitometer 110.
The adjusting means is realized by, for example, an air flow rate adjusting valve 118.
The first control means is realized, for example, by using the PID control unit 203.
The second control means is realized, for example, by using the FF control unit 205.
The plurality of calculation formulas are realized, for example, by using the formulas (1) to (9), (13), and (14).
<Claim 2>
The relationship between the feedforward control amount and the supply amount of the raw material to the crusher is realized by, for example, (∂FF control amount / ∂ coal supply amount) shown in Eq. (13).
The fluctuation amount of the supply amount of the raw material to the crusher is realized by, for example, the Δ coal supply amount represented by the equation (13).
The previously derived value of the feedforward control amount is realized by, for example, the FF control amount_previous value shown in Eq. (14) or the like. The amount of fluctuation of the feedforward control amount with respect to the previously derived value is realized by, for example, the ΔFF control amount shown in Eq. (14) or the like.
<Claim 3>
The means for measuring the flow rate of the diluted gas is realized by, for example, an orifice flow meter 117.
The means for measuring the flow rate of the fuel gas for generating hot air is realized by, for example, an orifice flow meter (not shown) for measuring the flow rate of the fuel gas sent to the hot gas generator 101.
The means for measuring the flow rate of combustion air for generating hot air is realized by, for example, an orifice flow meter (not shown) for measuring the flow rate of combustion air sent to the hot gas generator 101.
The means for measuring the flow rate of the emitted gas released into the atmosphere from the path is realized by, for example, an orifice flow meter (not shown) for measuring the flow rate of the emitted gas from the chimney 114 toward the atmosphere.
The calculation of the mass balance is realized by, for example, the calculation using the equations (15) and (16).
The flow rate of water vapor inside the path is realized, for example, by multiplying the WV shown in Eq. (3a) by a coefficient (22.4 / 18).
The amount of raw material supplied to the crusher is realized by, for example, the amount of coal supplied as shown in equation (3a).
The water content of the raw material after pulverization is realized by, for example, the water content of the product represented by the formula (3a).

101: Heat gas generator, 103: Bunker, 104: Coal dispenser, 105: Mill, 107: Bag filter, 110: Bag outlet O ₂ concentration meter, 118: Air flow rate control valve, 200: Oxygen concentration controller for crushing plant , 201: O ₂ concentration target value storage unit, 202: O ₂ concentration deviation derivation unit, 203: PID control unit, 204: mill outlet temperature target value storage unit, 205: FF control unit, 206: addition unit, 207: conversion Department

Claims (11)

A hot air generator that generates hot air as exhaust gas,
A crusher that crushes raw materials and releases the crushed raw materials to the outside along with the flow of exhaust gas, and a crusher in which the internal pressure is maintained at a negative pressure.
A collector that collects the crushed raw material released from the crusher along with the flow of the exhaust gas, and the internal pressure is maintained at a negative pressure.
A path through which the exhaust gas circulates via the hot air generator, the crusher, and the collector, and
A measuring means for measuring the oxygen concentration at a predetermined position inside the path, and
It has adjusting means for adjusting the injection amount of the diluting gas, which is a gas containing oxygen, into the path.
A crushing plant oxygen concentration control device that controls the oxygen concentration inside the path in a negative pressure type exhaust gas circulation system crushing plant in which the raw material is put into the inside of the crusher to crush the raw material.
Feedback control is performed to bring the measured value of the oxygen concentration at the predetermined position closer to the target value of the oxygen concentration at the predetermined position, and the flow rate of the diluted gas, which is the output of the feedback control, is derived as the feedback control amount. 1 control means and
The amount of the raw material supplied to the crusher, the amount of water in the raw material, the flow rate of air entering the inside of the crusher from the outside, the target value of the oxygen concentration at the predetermined position, and the outlet of the crusher. A plurality of calculation formulas having a target value of the temperature inside the path at a predetermined position on the side as a variable, the amount of heat given to the crushing plant of the negative pressure type / exhaust gas circulation system, and the negative pressure type / exhaust gas circulation. Calculation of heat balance that balances with the amount of heat consumed in the system crushing plant, the flow rate of gas injected into the negative pressure type / exhaust gas circulation system crushing plant, and the negative pressure type / exhaust gas circulation system crushing plant Calculate a plurality of calculation formulas for calculating the material balance that balances the sum of the flow rate of the generated gas and the flow rate of the gas discharged from the crushing plant of the negative pressure type / exhaust gas circulation system. A second control means for deriving the flow rate of the diluting gas required to maintain the target value of the oxygen concentration at the predetermined position as a feed forward control amount.
An addition means for adding the flow rate of the diluted gas derived by the second control means to the flow rate of the diluted gas derived by the first control means.
An instruction means for instructing the adjusting means to operate based on the added value of the flow rate of the diluted gas obtained by the adding means, and
A pulverization plant oxygen concentration control device characterized by having. The second control means is based on the relationship between the feedforward control amount and the supply amount of the raw material to the crusher, and the fluctuation amount of the supply amount of the raw material to the crusher. The pulverization plant oxygen concentration control according to claim 1, wherein the fluctuation amount with respect to the previously derived value of the control amount is derived, and the derived fluctuation amount is added to the previously derived value of the feedforward control amount. apparatus. The negative pressure type / exhaust gas circulation system crushing plant includes means for measuring the flow rate of the diluted gas, means for measuring the flow rate of the fuel gas for generating the hot air, and combustion air for generating the hot air. It further has a means for measuring the flow rate and a means for measuring the flow rate of the exhaust gas released into the air from the path.
The second control means includes a measured value of oxygen concentration at the predetermined position, a measured value of the flow rate of the emitted gas, a measured value of the flow rate of the diluted gas, and a measured value of the flow rate of the fuel gas. The material balance is calculated using the measured value of the flow rate of the combustion air, the flow rate of water vapor inside the path obtained from the result of the calculation, the amount of the raw material supplied to the crusher, and Based on the water content of the raw material after pulverization, the water content of the raw material is derived, and the water content of the raw material is used to calculate the plurality of calculation formulas to obtain the oxygen concentration at the predetermined position. The pulverization plant oxygen concentration control device according to claim 1 or 2, wherein the flow rate of the diluting gas required to maintain the target value is derived as a feed-forward control amount. The pulverization plant according to claim 3, wherein the second control means uses a representative value at a predetermined time for at least a part of the measured value when deriving the water content of the raw material. Oxygen concentration controller. The second control means is used in a period from the start of supply of the raw material to the crusher until a predetermined time elapses and a period in which the supply amount of the raw material to the crusher is changed. The pulverization plant oxygen concentration control device according to claim 3 or 4, wherein the value derived last time is used as the water content of the raw material. The pulverization plant oxygen concentration control device according to any one of claims 1 to 5, wherein the diluting gas is air. The pulverization plant oxygen concentration control device according to any one of claims 1 to 6, wherein the predetermined position is a position on the exit side of the collector. The pulverization plant oxygen concentration control device according to any one of claims 1 to 7, wherein the first control means performs at least a proportional operation as the feedback control. The pulverization plant oxygen concentration control device according to any one of claims 1 to 8, wherein the collector is a bag filter. A hot air generator that generates hot air as exhaust gas,
A crusher that crushes raw materials and releases the crushed raw materials to the outside along with the flow of exhaust gas, and a crusher in which the internal pressure is maintained at a negative pressure.
A collector that collects the crushed raw material released from the crusher along with the flow of the exhaust gas, and the internal pressure is maintained at a negative pressure.
A path through which the exhaust gas circulates via the hot air generator, the crusher, and the collector, and
A measuring means for measuring the oxygen concentration at a predetermined position inside the path, and
It has adjusting means for adjusting the injection amount of the diluting gas, which is a gas containing oxygen, into the path.
A crushing plant oxygen concentration control method for controlling the oxygen concentration inside the path in a negative pressure type exhaust gas circulation system crushing plant in which the raw material is put into the inside of the crusher to crush the raw material.
Feedback control is performed to bring the measured value of the oxygen concentration at the predetermined position closer to the target value of the oxygen concentration at the predetermined position, and the flow rate of the diluted gas, which is the output of the feedback control, is derived as the feedback control amount. 1 control process and
And supplies to the crusher of the raw material, the moisture content of the raw material, the flow rate of air entering from outside into the interior of the crusher, and the target value of the oxygen concentration in the predetermined position, the crusher A plurality of calculation formulas having a target value of the temperature inside the path at a predetermined position on the outlet side as variables, the amount of heat given to the crushing plant of the negative pressure type / exhaust gas circulation system, and the negative pressure type / exhaust gas. Calculation of heat balance that balances the amount of heat consumed in the crushing plant of the circulation system, the flow rate of gas injected into the crushing plant of the negative pressure type / exhaust gas circulation system, and the crushing plant of the negative pressure type / exhaust gas circulation system. Calculation of a plurality of calculation formulas for calculating the material balance that balances the sum of the flow rate of the gas generated in the above and the flow rate of the gas discharged from the crushing plant of the negative pressure type / exhaust gas circulation system. A second control step of deriving the flow rate of the diluting gas required to maintain the target value of the oxygen concentration at the predetermined position as a feed-forward control amount.
An addition step of adding the flow rate of the diluted gas derived by the second control step to the flow rate of the diluted gas derived by the first control step.
An adjustment step of operating the adjusting means based on the added value of the flow rate of the diluted gas obtained by the addition step, and an adjustment step of operating the adjusting means.
A method for controlling oxygen concentration in a pulverization plant, which comprises. A program characterized in that a computer functions as each means of the pulverization plant oxygen concentration control device according to any one of claims 1 to 9.

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