JP6702110B2 - Method, device and program for predicting inlet temperature of crusher in circulating crushing plant, and method, device and program for calculating raw material supply amount - Google Patents

Description

  The present invention is a method for predicting the inlet temperature of a crusher in a circulating crushing plant suitable for predicting the inlet temperature of a crusher in a circulatory crushing plant, an apparatus and a program, and a method for calculating a raw material supply amount, The present invention relates to a device and a program.

  A negative pressure type circulation system pulverization plant is known as a pulverization plant for producing pulverized coal, cement and the like (see, for example, Patent Document 1). In a negative pressure type circulation pulverization plant, fuel 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 a grinder that grinds the raw material. The raw material crushed by the crusher is supplied to the bag filter together with the exhaust gas and collected by the bag filter. After that, the exhaust gas is pressurized by the circulation fan and is supplied again as the circulation gas to the hot gas generator. The exhaust gas (hot air) thus generated in the hot gas generator is circulated from the hot gas generator to the hot gas generator via the crusher and the bag filter.

JP, 2014-114994, A

In this type of circulating crushing plant, the inlet temperature of the crusher varies greatly depending on the water content of the coal, the outside air temperature, the amount of crushed coal, etc., so it must be evaluated in advance at the plant design stage. If the inlet temperature of the crusher can be predicted with high accuracy according to the operating conditions of the plant, the equipment specifications can be optimized.
Particularly in a circulation type pulverization plant, since heated exhaust gas circulates in the line, the inlet temperature of the pulverizer tends to be higher than in a one-pass type pulverization plant which exhausts all the exhaust gas. Further, the crushing amount may be increased due to the structure capable of suppressing the exhaust gas emission amount by the exhaust gas circulation, and the inlet temperature of the crusher also tends to be high. Therefore, it can be said that in the circulation type pulverization plant, the demand for highly accurately predicting the inlet temperature of the pulverizer and optimizing the operating conditions is higher than that in the one-pass type pulverization plant.
Further, even during the operation of the circulation type crushing plant, if the inlet temperature of the crusher can be predicted with high accuracy, it can be effectively utilized for plant control.

However, it is hard to say that the method for predicting the inlet temperature of a crusher in a circulating crushing plant is well established.
Patent Document 1 discloses that heat/mass balance calculation is performed in a circulating system crushing plant, but does not disclose predicting the inlet temperature of the crusher.
In addition, the inlet temperature of a pulverizer in a circulation type pulverization plant is predicted according to a method for estimating the inlet temperature of a pulverizer in a one-pass type pulverization plant, but it is much higher than the actual temperature. The fact is that it often calculates low temperatures.

  The present invention has been made in view of the above points, and an object of the present invention is to enable highly accurate prediction of the inlet temperature of a crusher in a circulating crushing plant.

The gist of the present invention for solving the above problems is as follows.
[1] A hot gas generator that generates hot air as an exhaust gas, a crusher that crushes a raw material, and puts the crushed raw material on the flow of exhaust gas generated by the hot gas generator and discharges it to the outside; And a collector for collecting the pulverized raw material discharged along with the flow of exhaust gas from the exhaust gas from the collector by a circulation fan, and a part of the exhaust gas is diffused into the atmosphere. In a circulating system pulverizing plant circulated to a hot gas generator, a method of predicting the inlet temperature of the pulverizer,
The inlet temperature of the pulverizer is based on a heat balance that compensates for the amount of heat generated by the burner of the hot gas generator, the amount of work by the circulation fan, and the amount of exhaust heat due to the emission of exhaust gas into the atmosphere. based on the formulation the formula Te calculates the inlet temperature of the pulverizer,
The above formula is represented by the formula (102), and the inlet temperature T _IN of the crusher is expressed by the specific heat C of the gas, the outlet exhaust gas flow rate F _{bug of the} collector , the emission gas flow rate F _exh , and the outlet temperature T of the crusher. _{Using OUT} , the amount of heat ΔQ _HGG generated by the burner, the amount of work ΔQ _FAN by the circulation fan , and the outside air temperature T ₀ , according to the equation (102),
C・(F _bug −F _exh )・(T _IN −T _OUT )=
ΔQ _HGG + ΔQ _FAN + C·F _exh ·(T _OUT −T ₀ )・・・(102)
A method for predicting the inlet temperature of a crusher in a circulating system crushing plant, which is characterized by calculating .
[2] The circulation system according to [1], wherein the exhaust heat amount due to the emission of exhaust gas into the atmosphere is represented as the amount of heat required to heat the emitted gas from the outside temperature to the outlet temperature of the crusher. A method for predicting the inlet temperature of a crusher in a crushing plant.
[3] heat Delta] Q _HGG generated by the burner, as fuel gas calorie is constant, given more formula (101),
ΔQ _HGG = fuel gas calorie × fuel gas flow rate (101)
The work amount by the circulation fan is given a known value. The method for predicting the inlet temperature of a crusher in a circulatory crushing plant according to [1] or [2].
[ 4 ] The specific heat C of the gas and the work ΔQ _FAN by the circulation fan are given known values,
The discharge gas flow rate F _exh and the heat quantity ΔQ _HGG generated by the burner are set as operating conditions, and the outlet exhaust gas flow rate F _bug of the collector, the outlet temperature T _{OUT of} the crusher, and the outside air temperature T _{0 are set.} A method for predicting an inlet temperature of a crusher in a circulating system crushing plant according to any one of [1] to [3], which is calculated based on a heat and a mass balance using a condition including .
[ 5 ] A hot gas generator for generating hot air as exhaust gas, a crusher for crushing the raw material, and discharging the crushed raw material to the outside by putting it on the flow of the exhaust gas generated by the hot gas generator, and the crusher And a collector for collecting the pulverized raw material discharged along with the flow of exhaust gas from the exhaust gas from the collector by a circulation fan, and a part of the exhaust gas is diffused into the atmosphere. In a circulating system pulverizing plant that circulates to a hot gas generator, a device for predicting the inlet temperature of the pulverizer,
The inlet temperature of the pulverizer is based on a heat balance that compensates for the amount of heat generated by the burner of the hot gas generator, the amount of work by the circulation fan, and the amount of exhaust heat due to the emission of exhaust gas into the atmosphere. based on the formulation the formula Te, comprising means for calculating an inlet temperature of the pulverizer,
The above formula is represented by the formula (102), and the inlet temperature T _IN of the crusher is expressed by the specific heat C of the gas, the outlet exhaust gas flow rate F _{bug of the} collector , the emission gas flow rate F _exh , and the outlet temperature T of the crusher. _{Using OUT} , the amount of heat ΔQ _HGG generated by the burner, the amount of work ΔQ _FAN by the circulating fan , and the outside air temperature T ₀ , according to the equation (102),
C・(F _bug −F _exh )・(T _IN −T _OUT )=
ΔQ _HGG + ΔQ _FAN + C·F _exh ·(T _OUT −T ₀ )・・・(102)
An apparatus for predicting the inlet temperature of a crusher in a circulating crushing plant, which is characterized by calculating .
[ 6 ] A hot gas generator that generates hot air as exhaust gas, a crusher that crushes the raw material, and puts the crushed raw material on the flow of the exhaust gas generated by the hot gas generator and discharges it to the outside, and the crusher And a collector for collecting the pulverized raw material discharged along with the flow of exhaust gas from the exhaust gas from the collector by a circulation fan, and a part of the exhaust gas is diffused into the atmosphere. In a circulatory pulverization plant that circulates to a hot gas generator, a program for predicting the inlet temperature of the pulverizer,
The inlet temperature of the pulverizer is based on a heat balance that compensates for the amount of heat generated by the burner of the hot gas generator, the amount of work by the circulation fan, and the amount of exhaust heat due to the emission of exhaust gas into the atmosphere. Based on the formula formulated, the computer is caused to execute the process of calculating the inlet temperature of the crusher ,
The above formula is represented by the formula (102), and the inlet temperature T _IN of the crusher is expressed by the specific heat C of the gas, the outlet exhaust gas flow rate F _{bug of the} collector , the emission gas flow rate F _exh , and the outlet temperature T of the crusher. _{Using OUT} , the amount of heat ΔQ _HGG generated by the burner, the amount of work ΔQ _FAN by the circulation fan , and the outside air temperature T ₀ , according to the equation (102),
C・(F _bug −F _exh )・(T _IN −T _OUT )=
ΔQ _HGG + ΔQ _FAN + C·F _exh ·(T _OUT −T ₀ )・・・(102)
A program characterized by calculation .

[ 7 ] The inlet temperature of the pulverizer is repeatedly calculated by changing the raw material supply amount by the method for predicting the inlet temperature of the pulverizer in the circulating system pulverization plant according to any one of [1] to [ 4 ]. A step of obtaining a plurality of combinations of an inlet temperature of the crusher and a raw material supply amount,
Based on a plurality of combinations of the inlet temperature of the crusher and the raw material supply amount, a step of determining a maximum raw material supply amount within a range in which the inlet temperature of the crusher does not exceed the upper limit. Calculation method of the raw material supply in the crushing plant.
[ 8 ] The inlet temperature of the pulverizer is repeatedly calculated by changing the raw material supply amount by the method for predicting the inlet temperature of the pulverizer in the circulating system pulverization plant according to any one of [1] to [ 4 ]. A means for obtaining a plurality of combinations of an inlet temperature of the crusher and a raw material supply amount,
And a means for determining a maximum raw material supply amount within a range where the inlet temperature of the pulverizer does not exceed the upper limit, based on a plurality of combinations of the inlet temperature of the pulverizer and the raw material supply amount. A device for calculating the amount of raw material supplied in a circulating crushing plant.
[ 9 ] The inlet temperature of the pulverizer is repeatedly calculated by changing the raw material supply amount by the method for predicting the inlet temperature of the pulverizer in the circulation type pulverization plant according to any one of [1] to [ 4 ]. A process for obtaining a plurality of combinations of an inlet temperature of the crusher and a raw material supply amount,
A program for causing a computer to execute a process for obtaining a maximum raw material supply amount in a range in which the inlet temperature of the pulverizer does not exceed an upper limit, based on a plurality of combinations of the inlet temperature of the pulverizer and the raw material supply amount. ..

  According to the present invention, the inlet temperature of the pulverizer in the circulation type pulverization plant is the amount of heat generated by the burner of the hot gas generator, the amount of work by the circulation fan, and the amount of exhaust heat due to the emission of exhaust gas into the atmosphere. By calculating the inlet temperature of the crusher based on the heat balance to be supplemented, the inlet temperature of the crusher can be predicted with high accuracy.

It is a figure which shows the structural example of a negative pressure type|system|group pulverization system of circulation system. It is a flowchart which shows the prediction method of the mill inlet temperature in 1st Embodiment. It is a figure which shows the image of a heat balance model. It is a figure which shows the model which calculates a mill inlet temperature in 1st Embodiment. It is a figure which shows the model which calculates a mill inlet temperature following a 1-pass type|formula grinding plant. It is a characteristic view which shows the result of having compared the prediction method of the mill inlet temperature which applied this invention, and the prediction method of the mill inlet temperature which followed the 1-pass type|formula. It is a characteristic view which shows the result of having compared the prediction method of the mill inlet temperature which applied this invention, and the prediction method of the mill inlet temperature which followed the 1-pass type|formula. It is a flow chart which shows a calculating method of the maximum amount of coal supply in a 2nd embodiment. It is a figure for demonstrating the relationship of the parameter in 2nd Embodiment. It is a figure which shows the functional structure of the prediction apparatus of a mill inlet temperature, and a coal feed amount calculation apparatus.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a configuration example of a negative pressure type circulation system pulverization plant (hereinafter, simply referred to as a circulation system pulverization plant) for pulverizing coal in order to inject Pulverized Coal Injection (PCI) into a blast furnace. FIG. In FIG. 1, a solid line connecting the respective constituent elements indicates a pipe, and an arrow line indicates a traveling direction of gas or coal in the pipe.

In FIG. 1, a hot gas generator 101 has one or more burners, and uses fuel gas and combustion air (air) as inputs to the burner to control the air-fuel ratio of the burner and generate hot air as exhaust gas. The oxygen concentration of the exhaust gas is approximately 0%. In this embodiment, BFG (Blast Furnace Gas) is used as the fuel gas. In the air-fuel ratio control, the burner load transmitted from the temperature control device 200 and the flow rates of the fuel gas and the combustion air supplied to the burner are input, and the air-fuel ratio is controlled (for example, feedback control) and supplied to the burner. It is performed by adjusting the opening degree of each valve that adjusts the flow rates of the fuel gas and the combustion air. Here, the burner load indicates the ratio of the flow rate of the fuel gas supplied to the burner to the maximum value of the flow rate of the fuel gas that can be supplied to the burner. Further, since the air-fuel ratio control can be realized by a known technique by using a programmable logic controller (PLC) or the like, detailed description thereof will be omitted here.
The combustion air fan 102 sends combustion air to the hot gas generator 101.

The bunker 103 stores coal, which is a raw material. Since the pressure in the system is maintained at a certain slight negative pressure, air enters the system from the bunker 103 (bunker intrusion air).
The coal feeder 104 has a chain conveyor, and cuts coal stored in the bunker 103 by the chain conveyor and inputs it into the mill 105.
The mill 105 is a crusher that crushes the coal fed from the coal feeder 104. 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. The coal is crushed and crushed by rotating the crushing table 105b while pressing it against the rotating crushing table 105b. The crushed coal (hereinafter referred to as pulverized coal) is supplied to the upper part of the mill 105 by the flow of the exhaust gas supplied from the hot gas generator 101, is classified by a classifier, and is then discharged to the outside. To be done.

  The seal air fan 106 supplies the seal air to the gap inside the mill 105 (the bearing portion of the crushing table 105b), and the pulverized coal that is about to be discharged to the outside from the gap is supplied from the hot gas generator 101. Back into the flow of exhaust gas. The flow rate of the seal air is determined so that the pressure inside the mill 105 is less than the pressure of the seal air. As described above, in the seal air fan 106, pulverized coal enters the bearing portion of the crushing table 105b, resulting in poor lubrication of the bearing portion of the crushing table 105b, and from the bearing portion of the crushing table 105b to the outside. To prevent it from being released.

The bag filter 107 is a filter-type collector that collects the pulverized coal discharged from the mill 105 using a filter cloth. Foreign substances other than pulverized coal may be collected by the bag filter 107.
The foreign matter removing device 108 removes the foreign matter collected by the bag filter 107.
The reserve tank 109 stores the pulverized coal from which the foreign matter is removed by the foreign matter removing device 108. The pulverized coal stored in the reserve tank 109 is blown into the blast furnace from the tuyere of the blast furnace (the pulverized coal is blown).

The damper 112 adjusts the flow rate of the exhaust gas that has passed through the bag filter 107.
The circulation fan 113 pressurizes the exhaust gas so that the exhaust gas passing through the damper 112 can be circulated to the hot gas generator 101.
The desorption tower (chimney) 114 dissipates a part of the exhaust gas (dissipated gas) pressurized by the circulation fan 113 into the atmosphere.
The desorption system pressure regulating valve 115 regulates the pressure of the exhaust gas emitted from the desorption tower 114 into the atmosphere.

  The circulation system pressure regulating valve 116 regulates the pressure of the exhaust gas that has been boosted by the circulation fan 113 and is circulated to the hot gas generation device 101 without being diffused into the atmosphere via the diffusion tower 114. In this way, the exhaust gas generated by the hot gas generator 101 is supplied again to the hot gas generator 101 as a circulating gas, and the hot gas generator 101, the mill 105, the bag filter 107, the damper 112, the circulation fan 113, and the circulation fan are circulated. The system pressure regulating valve 116 and the path of the hot gas generator 101 are circulated.

The orifice flow meter 117 adjusts the flow rate of the dilution air so that the air in the atmosphere (dilution air) is supplied to the circulation system grinding plant.
The air flow rate adjusting valve 118 adjusts the flow rate of the air supplied to the circulation system crushing plant.
The dilution air fan 119 pressurizes the dilution air whose flow rate is adjusted by the air flow rate adjusting valve 118 and pushes the dilution air into the inlet side pipe of the hot gas generator 101. As a result, the oxygen concentration of the circulating gas can be increased.

As an index for managing such a circulation system crushing plant, an inlet temperature of the mill 105 (hereinafter referred to as “mill inlet temperature”) and an outlet temperature of the mill 105 (hereinafter referred to as “mill outlet temperature”) There is.
The mill inlet temperature is used as a control index for preventing hot gas overheating. An upper limit is set for the mill inlet temperature due to the relationship between the heat resistant temperature of the mill inlet expansion tube and the ignition temperature of coal.
The mill exit temperature is used as a control index for coal drying. Since the coal cannot be dried sufficiently when the mill outlet temperature decreases, it is preferable to keep the mill outlet temperature constant. To keep the mill outlet temperature constant, the mill outlet temperature is controlled. The mill outlet temperature control refers to the operation of the burner load in order to make the mill outlet temperature follow the target temperature, and feedback control is performed from the deviation of the mill outlet temperature measured by the mill outlet thermometer. PID control is generally used as the feedback control.

Hereinafter, a method for predicting the mill inlet temperature in the above-described circulation system crushing plant will be described.
As described above, if the inlet temperature of the crusher can be predicted with high accuracy according to the operating conditions of the plant, the equipment specifications can be optimized. In the present embodiment, the mill inlet temperature in the circulating system pulverization plant is calculated based on an offline heat/mass balance model so that it can be effectively utilized for preliminary evaluation of the plant design.

FIG. 2 is a flowchart showing a method for predicting the mill inlet temperature.
<Calculation of gas flow rate and heat quantity based on heat/mass balance model>
First, the gas (including air) flow rate and heat quantity are calculated based on the heat/mass balance model (step S1). In order to calculate the mill inlet temperature, the gas flow rate and heat quantity that satisfy the heat and mass balance are required for the entire process.
Therefore, the models [A] to [D] described below are _combined to calculate the BFG flow rate F _bfg , the combustion air flow rate F _cair , and the dilution air flow rate F _pair .

[Operating conditions]
Given the following parameters:
Mill outlet temperature (product temperature): T _OUT =90 [°C]
Coal supply: [ton/hr]
Exhaust gas flow rate at bag filter: F _bug [Nm ³ /hr]
O ₂ concentration at bag filter outlet: 10 [%]
Coal moisture: [%] * Moisture contained in coal before crushing Product moisture: 1.5 [%] * Moisture of pulverized coal after crushing and drying Ambient temperature: T ₀ [°C]
Bunker intrusion air flow rate: F _bair [Nm ³ /hr]
Seal air flow rate: F _sair [Nm ³ /hr]

Among these parameters, the coal supply amount is a representative parameter that can be artificially changed.
On the other hand, the bag filter outlet exhaust gas flow rate F _bug is given an appropriate set value with the suction capacity of the circulation fan 113 as the upper limit, for example. Further, the mill outlet temperature T _OUT and the O ₂ concentration at the bag filter outlet are optimum set values within a range in which the plant does not explode and the water vapor circulating in the plant does not become droplets and adhere to or corrode the pipes. Given.
For the product water content, for example, the pulverized coal collected by the bag filter 107 may be sampled and an average value may be set. As an example, 1.5[%] is empirically given.
As the outside air temperature T ₀ , for example, temperatures in summer and winter may be set, or intermediate temperatures may be set.
In the off-line calculation, the bunker _inflow air flow rate F _bair , the seal air flow rate F _sair , and the coal water content are unknown, but the calculation is performed after giving known values. For example, for coal moisture, raw material sampling may be performed and an average value thereof may be set.

[Calculation premise]
The initial temperature of all substances is the outside air temperature T ₀ , and the temperature of all gases (including steam) and pulverized coal becomes the mill outlet temperature T _{OUT due} to the hot air discharged from the burner.
Further, all the gas injected or generated in the system is diffused from the diffusion tower 114, and the pressure in the system is kept at a constant slight negative pressure.

[Method of calculation]
The calculation method of the gas flow rate based on the heat/mass balance model is shown.
[A] Emission gas flow rate model The emission gas flow rate F _exh from the diffusion tower 114 is expressed by equation (1). F _cv is the steam flow rate derived from coal.
F _exh =F _bfg +F _cair +F _cv +F _sair +F _bair +F _pair (1)

[B] O ₂ density model O ₂ concentration in the bag filter outlet by the gas component, represented by the formula (2). The O ₂ concentration target value is, for example, 10%.
O ₂ concentration=(F _pair +F _bair +F _sair +F _cair ×0.1)×21/F _exh (2)

[C] Coal Moisture Model A coal-derived steam flow rate F _cv can be associated with the weight WV of water existing as steam per unit time. The product moisture is, for example, 1.5[%].
F _cv =WV×18/22.4
WV=coal supply amount×1000×{coal moisture/(100−coal moisture)−product moisture/(100−product moisture)}...(3)

[D] Heat Balance Model In addition to the models of [A] to [C], the following heat balance equations can be _combined to calculate the BFG flow rate F _bfg , the combustion air flow rate F _cair , and the dilution air flow rate F _pair. it can.
FIG. 3 shows an image of the heat balance model. As shown in FIG. 3, the equation (4) is established for the amount of heat ΔQ _HGG generated by the burner and the amount of work (compression heat) ΔQ _FAN by the circulation fan 113.
ΔQ _HGG + ΔQ _FAN
= ΔQ latent heat + ΔQ sensible heat + ΔQ coal + ΣΔQ _GAS (i) (4)

Here, the heat quantity ΔQ _GAS (i) required to heat various gases from the gas injection temperature (=outside air temperature) to the product temperature (=mill outlet temperature) is expressed by the equation (5). i represents the type of gas.
ΔQ _GAS (i)=gas specific heat (i) [kcal/Nm ³ /° C.]×gas flow rate (i)×(product temperature−gas injection temperature (i)) (5)
Specifically, consider i=1 to 5. Assuming that i=1 is BFG gas, i=2 is burner combustion air, i=3 is seal air, i=4 is bunker entry air, and i=5 is dilution air, it can be interpreted as follows. ..
The gas specific heat (1) is the specific heat of BFG, and the gas specific heats (2) to (5) are the specific heat of air. The gas flow rate is as follows.
Gas flow rate (1) = F _bfg
Gas flow rate (2) = F _cair
Gas flow rate (3) = F _sair
Gas flow rate (4) = F _bair
Gas flow rate (5) = F _pair
The gas injection temperatures (1) to (5) are the outside air temperature T ₀ .
here,
F _cair =F _bfg × theoretical air amount × excess air amount. For example, the theoretical air amount of BFG gas is 0.638 and the excess air amount is 1.1.

Further, the heat quantity ΔQ coal required to heat the coal from the raw material temperature (=outside air temperature) to the product temperature (=mill outlet temperature) is represented by the formula (6).
ΔQ coal=coal specific heat [kcal/kg/° C.]×coal supply amount×1000×(product temperature-raw material temperature) (6)
The raw material temperature is the outside air temperature T ₀ .

Further, the heat quantity ΔQ sensible heat required to heat the coal moisture from the raw material temperature (=outside air temperature) to the product temperature (=mill outlet temperature) is represented by the equation (7).
ΔQ sensible heat=water specific heat [kcal/kg/° C.]×WM×(product temperature-raw material temperature) (7)
Here, the weight WM of the water brought in by the coal per unit time is represented by the equation (8).
WM=coal supply amount×1000×coal moisture/(100−coal moisture) (8)
The raw material temperature is the outside air temperature T ₀ .

Further, the heat quantity ΔQ latent heat required for evaporation of coal moisture is represented by the equation (9). The weight WV of water existing as water vapor per unit time is as shown in formula (3).
ΔQ latent heat = latent heat of water [kcal/kg] × WV (9)

Further, the heat quantity ΔQ _HGG generated by the burner is expressed by the equation (10). BFG calories [kcal/Nm ³ ] are assumed to be constant.
ΔQ _HGG = BFG calorie × F _bfg (10)

Further, the work amount ΔQ _FAN by the circulation fan 113 is represented by the equation (11) as a known value determined by the hardware specifications.
ΔQ _FAN = constant (11)

In the heat/mass balance calculation, input known physical quantities (various specific heats, latent heat of water, work amount by the circulation fan 113, BFG calories), and satisfy the mathematical expressions described in the models [A] to [D]. It is achieved by iterative calculation.
Specifically, F _bfg , F _cair , and F _pair that simultaneously satisfy the heat/mass balance calculation described by the equation (4) and the constraint conditions regarding the O ₂ concentration described by the equations (1) and (2) are _defined as Will be calculated. The repetitive calculation refers to repeating until the absolute value of the following deviation becomes a fixed value (for example, the ΔO ₂ concentration is 0.01%) or less.
ΔQ=ΔQ _HGG +ΔQ _FAN −{ΔQ latent heat +ΔQ sensible heat +ΔQ coal +ΣΔQ _GAS (i)}
ΔO ₂ concentration=O ₂ concentration target _value− (F _pair +F _bair +F _sair +F _cair ×0.1)×21/F _exh
First, the BFG flow rate and the combustion air flow rate are calculated on the assumption that the dilution air flow rate is zero in the equation (4). Next, the emission gas flow rate F _exh is calculated based on the equation (1), and the flow rate F _{pair of the} dilution air that satisfies the constraint condition regarding the O ₂ concentration is derived from the equation (2). Again, the derived flow rate of the dilution air is given to the equation (4) to calculate the BFG flow rate/combustion air flow rate. These iterative calculations are repeated until the absolute value of the ΔO ₂ concentration becomes a certain value (for example, 0.01%) or less.
As a result, the BFG flow rate F _bfg , the combustion air flow rate F _cair , and the dilution air flow rate F _pair that satisfy the heat and mass balance are calculated.

<Calculation of mill inlet temperature>
Next, the mill inlet temperature is calculated (step S2).
The mill inlet temperature T _IN is calculated by the formula (12) based on the result of the heat/mass balance calculation calculated by the models [A] to [D].
Here, the specific heat C of the gas is treated as a known value. Since the parameters other than the mill inlet temperature T _IN are set values or values calculated by the models [A] to [D], the “mill inlet temperature” can be calculated immediately from the equation (12).
C・(F _bug −F _exh )・(T _IN −T _OUT )=
ΔQ _HGG + ΔQ _FAN + C・F _exh・(T _OUT −T ₀ )・・・(12)

As shown in FIG. 4, the formula (12) is a formula based on its heat balance after simplifying the structure of the circulation system crushing plant by ignoring the temperature distribution and the flow rate distribution and making it a lumped constant. is there. That is, the temperature of the entire system is represented by the mill outlet temperature T _OUT , and the mill inlet flow rate is defined by F _bug −F _exh . The mill inlet temperature T _IN must _complement the amount of heat ΔQ _HGG generated by the burner, the amount of work ΔQ _FAN by the circulation fan 113, and the amount of exhaust heat due to the emission of exhaust gas into the atmosphere. The amount of heat exhausted by the emission of exhaust gas into the atmosphere is _expressed as the amount of heat C·F _exh ·(T _OUT −T ₀ ) required to heat the emitted gas from the outside temperature to the mill outlet temperature.

Here, as a comparative example, it is considered to calculate the mill inlet temperature T _IN according to the method of predicting the inlet temperature of the pulverizer in the one-pass type pulverization plant.
A calculation formula following the one-pass formula is expressed by formula (13). F _cir is the circulating gas flow rate, and F _IN is the mill inlet flow rate.
C・F _IN・T _IN =ΔQ _HGG +ΔQ _FAN +C・F _cir・T _OUT +C・(F _pair +F _bfg +F _cair )...(13)
However,
F _IN =F _bug −F _exh ＋F _pair ＋F _bfg ＋F _cair
F _cir =F _bug −F _exh

Formula (13) is formulated as follows.
First, in the case of the one-pass type, the mill inlet temperature is calculated as follows. FIG. 5A shows a model in which the structure of the one-pass type crushing plant is simplified. After calculating ΔQ _HGG corresponding to the mill outlet temperature T _OUT , the mill inlet temperature T _IN is calculated by a simple heat balance as shown in equation (14).
ΔQ _HGG + ΔQ _FAN =C·F _IN ·(T _IN −T ₀ )・・・(14)
F _IN =flow rate of cold air +flow rate of combustion exhaust gas

When this idea is applied to a circulating system crushing plant, it is modeled as shown in FIG. F _HGG is the combustion exhaust gas flow rate and is given by the sum of the BFG flow rate F _bfg and the combustion air flow rate F _cair .
F _IN =F _cir +F _HGG +F _pair (15)
ΔQ _HGG +C・(F _pair +F _HGG )・T ₀ +C・F _cir・T _cir
=C. _FIN・T _IN・・・(16)
C·F _cir ·(T _cir −T _OUT )=ΔQ _FAN ...(17)
By rearranging these equations, equation (13) is obtained.

6 and 7, based on the actual operation data, a method of predicting the mill inlet temperature based on the equation (12) (called an invention method) and a mill inlet temperature following the one-pass equation based on the equation (13). The result of comparison with the prediction method (called the conventional method) is shown.
FIG. 6A shows the BFG flow rate, the dilution air flow rate, and the coal feed rate setting change rate limit in the actual operation data.
FIG. 6B shows the actual mill inlet temperature, the mill inlet temperature calculated by the inventive method, and the mill inlet temperature calculated by the conventional method. Further, FIG. 7 shows the deviation degree between the mill inlet temperature calculated by the inventive method and the mill inlet temperature calculated by the conventional method with respect to the actual mill inlet temperature.
As shown in FIGS. 6(b) and 7, the mill inlet temperature calculated by the conventional method is much lower than the actual temperature, and empirically, as the milling amount increases, The temperature deviates from the actual temperature, and an error of 100° C. or more occurs depending on the pulverization amount. On the other hand, the mill inlet temperature calculated by the inventive method is almost the same as the actual temperature, and it can be seen that the actual operation data can be well reproduced.

FIG. 10A shows a functional configuration of a mill inlet temperature predicting apparatus for realizing the above-described mill inlet temperature predicting method.
The input unit 1001 is a condition necessary for predicting the mill inlet temperature, specifically, the mill outlet temperature T _OUT , the coal supply amount, the bag filter outlet exhaust gas flow rate F _bug , the bag filter outlet O ₂ concentration, the coal moisture, the product. water, outside air temperature T _0, bunker penetration air flow F _bair, enter the seal air flow F _SAIR.
Further, the input unit 1001 inputs various specific heats, latent heat of water, work amount by the circulation fan 113, and BFG calories.
These pieces of information may be input by an operator via an input device (not shown) or may be input by an external device via a network.

The heat/mass balance calculation unit 1002 calculates the gas flow rate and heat quantity based on the heat/mass balance model described in step S1 based on the information input by the input unit 1001.
The mill inlet temperature calculation unit 1003 uses the calculation result of the heat/mass balance calculation unit 1002 to calculate the mill inlet temperature described in step S2.
The output unit 1004 outputs the mill inlet temperature calculated by the mill inlet temperature calculation unit 1003. For example, the mill inlet temperature is displayed on a display (not shown) or sent to an external device.

  As described above, the method for predicting the mill inlet temperature to which the present invention is applied is completely different from the one that follows the conventional one-pass method, and is a unique one that reflects the characteristics of the circulation system crushing plant. Can be expressed well. As a result, it can be utilized as a preliminary evaluation for optimizing equipment specifications such as the capacity of the circulation fan 113 and the heat resistant temperature of the mill inlet expansion tube, which contributes to higher precision in plant design. In particular, when the crushing amount is increased, how much the capacity of the circulation fan 113 should be is an important issue related to the equipment cost, and it becomes possible to correctly select the equipment. And, for example, even when the coal moisture and the outside air temperature change depending on the weather and the coal type, the mill inlet temperature can be predicted with high accuracy, and as a result, the mill inlet temperature does not exceed the upper limit (for example, 400° C.). It is possible to properly design various plant operating conditions.

(Second embodiment)
In the first embodiment, an example of performing offline calculation has been described so that it can be effectively used for preliminary evaluation of plant design.
In the second embodiment, an example will be described in which online calculation is performed so that it can be effectively used to perform plant control during operation of a circulation system crushing plant. Specifically, the mill inlet temperature in the circulating system pulverization plant is calculated based on an online heat/mass balance model, and the maximum amount of coal supply within the range where the mill inlet temperature does not exceed the upper limit (for example, 400°C) ( Calculate the maximum amount of coal supply.

FIG. 8 is a flowchart showing a method of calculating the coal supply amount.
<Estimation of coal moisture>
First, coal moisture is estimated (step S11). In order to calculate the mill inlet temperature with high accuracy, it is necessary to estimate the water content of coal in actual operation.
Here, as shown in FIG. 9, in the circulating system crushing plant, the flow rates of various gases, the O ₂ concentration at the bag filter outlet, the mill inlet temperature and the mill outlet temperature are measured, and the coal moisture and the bunker intrusion are measured. The air flow rate F _bair and the seal air flow rate F _sair are unknown quantities.

[Operating conditions]
Given the following parameters:
Mill outlet temperature (product temperature): Actual value T _OUT
Coal supply: Set value [ton/hr]
Exhaust gas flow rate at bag filter: Actual value F _bug [Nm ³ /hr]
O ₂ concentration at bag filter outlet: Actual value [%]
Product water content: 1.5 [%] * Water content of pulverized coal after crushing and drying Outside air temperature: Actual value T ₀ [°C]
Emission gas: Actual value F _exh [Nm ³ /hr]
BFG flow rate: Actual value F _bfg [Nm ³ /hr]
Combustion air flow rate: Actual value F _cair [Nm ³ /hr]
Dilution air flow rate: Actual value F _pair [Nm ³ /hr]

[Method of calculation]
The _desorption gas flow rate F _exh from the _desorption tower 114 is represented by the equation (1).
Further, the O ₂ concentration [%] at the bag filter outlet is expressed by the equation (2).
In Equations (1) and (2), the coal-derived steam flow rate F _cv , the bunker _inflow air flow rate F _bair, and the seal air flow rate F _sair are unknown quantities. Equation (1) and solving the simultaneous equation (2) can be calculated and the steam flow rate F _cv from coal, and a sum of the bunker penetration air flow F _bair and seal air flow F _SAIR.
Then, when the steam flow rate F _cv derived from coal is obtained, the coal water content can be calculated from the equation (3). As a result, it is possible to calculate the coal moisture, the sum of the bunker penetration air flow F _bair and seal air flow F _SAIR.

<Calculation of gas flow rate and heat quantity based on heat and mass balance model, and calculation of mill inlet temperature>
Next, and coal water obtained in step S11, by using the sum of the bunker penetration air flow F _bair and seal air flow F _SAIR, performs calculation of the gas flow rate and the quantity of heat based on heat and mass balance model (Step S12) , The mill inlet temperature is calculated (step S13).
Steps S12 and S13 are similar to steps S1 and S2 described in the first embodiment, and a detailed description thereof will be omitted here, but here, the coal feed rate is changed a plurality of times and the mill inlet temperature is changed. The above calculation is repeated to obtain a plurality of combinations of the mill inlet temperature and the feed rate.
The parameters are summarized as follows.
・Parameters that are changed multiple times Coal supply: [ton/hr]
・Fixed parameter (set value)
Mill outlet temperature (product temperature): T _OUT =90 [°C]
Exhaust gas flow rate at bag filter: F _bug [Nm ³ /hr]
O ₂ concentration at bag filter outlet: 10 [%]
Product moisture: 1.5[%]
・Fixed parameter (actual value)
Outside temperature: Actual value T ₀ [℃]
・Fixed parameter (estimated value)
Coal moisture [%]
The sum of the bunker penetration air flow F _bair and seal air flow _F sair [Nm ³ / hr]

<Calculation of coal supply amount>
Next, based on a plurality of combinations of the mill inlet temperature and the coal feed amount, the maximum coal feed amount (maximum coal feed amount) is determined within the range where the mill inlet temperature does not exceed the upper limit (for example, 400° C.) (step. S14).
[Method of calculation]
The data set obtained in steps S12 and S13 is created to obtain an approximate function of Y: mill inlet temperature and X: coal feed amount, and the coal feed amount at which the mill inlet temperature becomes 400° C. is obtained from the approximate function. calculate.
Specifically, first, the set value "coal supply amount_k" of the coal supply amount is given, and the mill inlet temperature is predicted in steps S12 and S13. The predicted value of this mill inlet temperature is called "T _IN _k". It should be noted that the steps S12 and S13 can be simply expressed as shown in Expression (18). In the equation (18), φ represents a function for calculating the mill inlet temperature with the coal feed rate as a variable.
T _IN _k=φ (coal supply amount_k) (18)

For example, calculate the predicted values of the mill inlet temperature at the following four different coal feed rates.
T _IN _1 = φ (coal supply amount -1)
T _{IN —} 2 = φ (coal supply amount — 2)
T _IN _3=φ (coal supply_3)
T _IN _4=φ (coal supply_4)
Coal supply amount =1=minimum coal supply amount (amount defined by the minimum value of the belt speed of the coal feeder 104), coal supply amount_4=maximum coal supply (at the maximum value of the belt speed of the coal feeder 104) (Specified amount),
Coal supply amount_2 = (Coal supply amount_4-Coal supply amount_1) x 1/3+ Coal supply amount_1
Coal supply_3=(Coal supply_4_Coal supply_1)×2/3+Coal supply_1
And

Next, the data set (X, Y) = (Kyusumiryou _{_1, T IN _1), (} ( Kyusumiryou _2, T _IN _2), (Kyusumiryou _{_3, T IN _3), (} ( Coefficients (A, B, C) are calculated by the least squares method, assuming a quadratic function of equation (19) for the coal supply amount_4, T _IN _4).
Y=A·X ² +B·X+C (19)

Then, based on (Equation 19) having the obtained coefficients (A, B, C),
400=A・X ² +B・X+C
The amount of coal supply X (>0) that satisfies the above condition is calculated.

FIG. 10B shows a functional configuration of a coal supply amount calculation device for realizing the above-described coal supply amount calculation method.
The input unit 1101 is a condition necessary for estimating coal moisture, specifically, the actual value T _OUT of the mill outlet temperature, the coal feed rate, the actual value F _{bug of} the exhaust gas flow rate of the bag filter outlet, and the O ₂ concentration of the bag filter outlet. , Actual product value of water, actual value of external temperature T ₀ , actual value of _exhaled gas F _exh , actual value of BFG flow rate F _bfg , actual value of combustion air flow rate F _cair , actual value of dilution air flow rate F _pair To do.
In addition, the input unit 1101 is a condition necessary for predicting the mill inlet temperature, specifically, a product temperature (mill outlet temperature) T that is a coal supply amount that is a parameter that is changed a plurality of times and a fixed parameter (setting value). Input _OUT , bag filter outlet exhaust gas flow rate F _bug , bag filter outlet O ₂ concentration, and product moisture.
The input unit 1101 also inputs various types of specific heat, latent heat of water, work amount by the circulation fan 113, and BFG calories.
These pieces of information may be input by an operator via an input device (not shown) or may be input by an external device via a network.

The coal moisture calculation unit 1102 estimates the coal moisture described in step S11 based on the condition input by the input unit 1101.
The heat/mass balance calculation unit 1103, based on the coal moisture estimated by the coal moisture calculation unit 1102 and the condition input by the input unit 1101, the gas flow rate and heat quantity based on the heat/mass balance model described in step S12. Calculate.
The mill inlet temperature calculation unit 1104 calculates the mill inlet temperature described in step S13 using the calculation result of the heat/mass balance calculation unit 1103.
The maximum coal feed rate calculation unit 1105 calculates the mill inlet temperature based on a plurality of combinations of the mill inlet temperature and the coal feed amount obtained by the iterative calculation in the heat/mass balance calculation unit 1103 and the mill inlet temperature calculation unit 1104. Find the maximum amount of coal supply within the range that does not exceed the upper limit.
The output unit 1106 outputs the maximum coal supply amount calculated by the maximum coal supply amount calculation unit 1105. For example, the maximum coal supply amount is displayed on a display (not shown). Further, the maximum coal supply amount may be sent to a control device that controls the coal supply amount, and the control device may execute the coal supply amount control based on the maximum coal supply amount.

  As described above, it is possible to estimate coal moisture by inputting actual measurement data in the operation. Then, based on the estimated value of coal moisture, the maximum amount of coal supply is determined within the range where the mill inlet temperature value does not exceed the upper limit value. As a result, even when the water content of the coal and the ambient temperature change depending on the weather or the type of coal, the maximum throughput can always be achieved, and the productivity of the crushing plant can be improved.

  The mill inlet temperature prediction device and the coal feed amount calculation device can be realized by a computer device including a CPU, a ROM, a RAM, and the like. The CPU functions as each unit shown in FIGS. 10A and 10B by using the RAM as the main memory and the work area and executing the programs stored in the ROM and the external memory.

Although the present invention has been described with the embodiments, the above embodiments merely show examples of embodying the present invention, and the technical scope of the present invention is construed in a limited manner by these. It must not be. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.
The present invention also provides software (program) that implements the functions of the present invention to a system or apparatus via a network or various storage media, and the computer of the system or apparatus reads and executes the program. It is feasible.

  101: Hot gas generator, 105: Mill, 107: Bag filter, 113: Circulation fan, 114: Dispersion tower, 1001: Input unit, 1002: Heat/mass balance calculation unit, 103: Mill inlet temperature calculation unit, 1004: Output unit, 1101: Input unit, 1102: Coal moisture calculation unit, 1103: Heat/mass balance calculation unit, 1104: Mill inlet temperature calculation unit, 1105: Maximum coal feed amount calculation unit, 1106: Output unit

Claims (9)

A hot gas generator that generates hot air as an exhaust gas, a raw material that is crushed, and a crusher that discharges the raw material after crushing to the outside by placing it on the flow of the exhaust gas that is generated by the hot gas generator, and the exhaust gas from the crusher. A collector for collecting the pulverized raw material discharged along with the flow, and a part of the exhaust gas from the collector is diffused into the atmosphere by a circulation fan, and the hot gas is generated. A method for predicting the inlet temperature of the crusher in a circulatory pulverization plant circulating in the device,
The inlet temperature of the pulverizer is based on a heat balance that compensates for the amount of heat generated by the burner of the hot gas generator, the amount of work by the circulation fan, and the amount of exhaust heat due to the emission of exhaust gas into the atmosphere. based on the formulation the formula Te calculates the inlet temperature of the pulverizer,
The above formula is represented by the formula (102), and the inlet temperature T _IN of the crusher is expressed by the specific heat C of the gas, the outlet exhaust gas flow rate F _{bug of the} collector , the emission gas flow rate F _exh , and the outlet temperature T of the crusher. _{Using OUT} , the amount of heat ΔQ _HGG generated by the burner, the amount of work ΔQ _FAN by the circulation fan , and the outside air temperature T ₀ , according to the equation (102),
C・(F _bug −F _exh )・(T _IN −T _OUT )=
ΔQ _HGG + ΔQ _FAN + C·F _exh ·(T _OUT −T ₀ )・・・(102)
A method for predicting the inlet temperature of a crusher in a circulating system crushing plant, which is characterized by calculating .   The amount of heat exhausted by the emission of exhaust gas into the atmosphere is expressed as the amount of heat required to heat the emitted gas from the ambient temperature to the outlet temperature of the crusher, in the circulating system pulverization plant according to claim 1. Prediction method of inlet temperature of crusher. Heat Delta] Q _HGG generated by the burner, as fuel gas calorie is constant, given more formula (101),
ΔQ _HGG = fuel gas calorie × fuel gas flow rate (101)
The method for predicting the inlet temperature of a crusher in a circulating system crushing plant according to claim 1 or 2, wherein the work amount of the circulating fan is given a known value. Known values are given to the specific heat C of the gas and the work amount ΔQ _FAN by the circulation fan,
The discharge gas flow rate F _exh and the heat quantity ΔQ _HGG generated by the burner are set as operating conditions, and the outlet exhaust gas flow rate F _bug of the collector, the outlet temperature T _{OUT of} the crusher, and the outside air temperature T _{0 are set.} The method for predicting the inlet temperature of a crusher in a circulating system crushing plant according to any one of claims 1 to 3, wherein the method is calculated based on heat and mass balance using conditions including A hot gas generator that generates hot air as an exhaust gas, a raw material that is crushed, and a crusher that discharges the raw material after crushing to the outside by placing it on the flow of the exhaust gas that is generated by the hot gas generator, and the exhaust gas from the crusher. A collector for collecting the pulverized raw material discharged along with the flow, and a part of the exhaust gas from the collector is diffused into the atmosphere by a circulation fan, and the hot gas is generated. In a circulating pulverization plant to circulate in the device, a device for predicting the inlet temperature of the pulverizer,
The inlet temperature of the pulverizer is based on a heat balance that compensates for the amount of heat generated by the burner of the hot gas generator, the amount of work by the circulation fan, and the amount of exhaust heat due to the emission of exhaust gas into the atmosphere. based on the formulation the formula Te, comprising means for calculating an inlet temperature of the pulverizer,
The above formula is represented by the formula (102), and the inlet temperature T _IN of the crusher is expressed by the specific heat C of the gas, the outlet exhaust gas flow rate F _{bug of the} collector , the emission gas flow rate F _exh , and the outlet temperature T of the crusher. _{Using OUT} , the amount of heat ΔQ _HGG generated by the burner, the amount of work ΔQ _FAN by the circulation fan , and the outside air temperature T ₀ , according to the equation (102),
C・(F _bug −F _exh )・(T _IN −T _OUT )=
ΔQ _HGG + ΔQ _FAN + C·F _exh ·(T _OUT −T ₀ )・・・(102)
An apparatus for predicting the inlet temperature of a crusher in a circulating crushing plant, which is characterized by calculating . A hot gas generator that generates hot air as an exhaust gas, a raw material that is crushed, and a crusher that discharges the raw material after crushing to the outside by placing it on the flow of the exhaust gas that is generated by the hot gas generator, and the exhaust gas from the crusher. A collector for collecting the pulverized raw material discharged along with the flow, and a part of the exhaust gas from the collector is diffused into the atmosphere by a circulation fan, and the hot gas is generated. In a circulating pulverization plant to be circulated in the device, a program for predicting the inlet temperature of the pulverizer,
The inlet temperature of the pulverizer is based on a heat balance that compensates for the amount of heat generated by the burner of the hot gas generator, the amount of work by the circulation fan, and the amount of exhaust heat due to the emission of exhaust gas into the atmosphere. Based on the formula formulated, the computer is caused to execute the process of calculating the inlet temperature of the crusher ,
The above formula is represented by the formula (102), and the inlet temperature T _IN of the crusher is expressed by the specific heat C of the gas, the outlet exhaust gas flow rate F _{bug of the} collector , the emission gas flow rate F _exh , and the outlet temperature T of the crusher. _{Using OUT} , the amount of heat ΔQ _HGG generated by the burner, the amount of work ΔQ _FAN by the circulation fan , and the outside air temperature T ₀ , according to the equation (102),
C・(F _bug −F _exh )・(T _IN −T _OUT )=
ΔQ _HGG + ΔQ _FAN + C·F _exh ·(T _OUT −T ₀ )・・・(102)
A program characterized by calculations . The inlet temperature of the pulverizer is repeatedly calculated by changing the raw material supply amount by the method for predicting the inlet temperature of the pulverizer in the circulating system pulverization plant according to any one of claims 1 to 4 , Obtaining multiple combinations of inlet temperature and feed rate,
Based on a plurality of combinations of the inlet temperature of the crusher and the raw material supply amount, a step of determining a maximum raw material supply amount within a range in which the inlet temperature of the crusher does not exceed the upper limit. Calculation method of the raw material supply in the crushing plant. The inlet temperature of the pulverizer is repeatedly calculated by changing the raw material supply amount by the method for predicting the inlet temperature of the pulverizer in the circulating system pulverization plant according to any one of claims 1 to 4 , Means for obtaining a plurality of combinations of inlet temperature and raw material supply,
And a means for determining a maximum raw material supply amount within a range where the inlet temperature of the pulverizer does not exceed the upper limit, based on a plurality of combinations of the inlet temperature of the pulverizer and the raw material supply amount. A device for calculating the amount of raw material supplied in a circulating crushing plant. The inlet temperature of the pulverizer is repeatedly calculated by changing the raw material supply amount by the method for predicting the inlet temperature of the pulverizer in the circulating system pulverization plant according to any one of claims 1 to 4 , A process of obtaining a plurality of combinations of an inlet temperature and a raw material supply amount,
A program for causing a computer to execute a process for obtaining a maximum raw material supply amount in a range in which the inlet temperature of the pulverizer does not exceed an upper limit, based on a plurality of combinations of the inlet temperature of the pulverizer and the raw material supply amount. ..

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