JPH11304143A - Boiler fuel mixing control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a boiler fuel mixing control device which is suitable for realizing the economical operational performance of a boiler by mixing various kinds of fuel. SOLUTION: A boiler fuel mixing control device used for a boiler device provided with a furnace 7 equipped with a burner 4, a water screen 12 surrounding the furnace 7, and a superheater 18 which superheats the steam generated from the water screen 12 in the exhaust gas flow passage of the furnace 7 is provided with a detecting means which detects the ratio of the heat-exchanging amount of the water screen 12 to that of the superheater 18, a plurality of fuel supplying means 55 and 56 which respectively supply a plurality of kinds of fuel having different combustion speeds, fuel adjusting means 51 and 52 which respectively adjust the flow rates of the plurality of kinds of fuel supplied by means of the supplying means 55 and 56, and a mixing means which mixes the plurality of kinds of fuel adjusted by means of the adjusting means 51 and 52 and supplies the mixed fuel to the burner 4. The controller detects the increase or decrease of the ratio of the heat-exchanging amount of the water screen 12 to that of the superheater 18 by means of the detecting means and decreases or increases the mixing ratio of the fuel having the faster combustion speed by adjusting the flow rates of the plurality of kinds of fuel based on the detected result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiler control apparatus, and more particularly to a boiler fuel mixing control apparatus suitable for realizing economically good boiler operation performance by mixing various fuels.

[0002]

2. Description of the Related Art FIG. 3 shows a once-through boiler apparatus body according to the prior art. The flow rate of the fuel line 1 is adjusted by the flow rate adjusting means 2. The flow rate adjusting means 2 adjusts a valve opening degree for liquid fuel, a damper opening degree for gaseous fuel, a belt conveyor speed to a coal pulverizer for coal, and the like. To follow. The fuel is burned by a burner 4 provided in a furnace 7. At this time, the combustion air is supplied from the air register 8 through the air line 5 to the inside of the furnace through the ventilator 6.

On the other hand, water is supplied from a water supply line 10 through a pump 11 to a water wall 12 surrounding a furnace, and is converted into steam in the water wall. A part of the water wall becomes a screen 13 on a lattice, between which the furnace exhaust gas 9 passes. The steam generated at the water wall is superheated while passing through the water wall of the furnace upper part and the ceiling, and the temperature is measured by the temperature detector 14. Thereafter, the steam is mixed with the water injection 17 in the desuperheater 15, and at this time, the water injection amount is adjusted by the water injection valve 17.

[0004] Further, the temperature of the steam is increased by a superheater 18,
The amount of superheated gas at that time is adjusted by the gas damper 19. After the temperature of the steam exiting the superheater 18 is measured by a temperature detector 20, the steam is supplied to a high-pressure turbine 22 through a main steam line 21. The steam expanded by the work in the turbine 22 enters the reheater 24 via the low-temperature reheat steam line 23 and is heated again, and the amount of the heated gas at that time is adjusted by the gas damper 25. The steam exiting the reheater 24 is supplied to a low-pressure turbine 28 via a high-temperature reheat steam line 27.

The exhaust gas passing through the superheater 18 or the reheater 24 is supplied to the gas recirculation line 3 according to the opening degree of the damper 29.
After passing through 0, it is put into the bottom of the furnace through the ventilator 31.

[0006] This lowers the furnace gas temperature to lower the amount of radiant heat transfer of the furnace water wall 12, while increasing the amount of gas passing through the superheater 18 and the reheater 24 to increase the contact heat transfer at the above-mentioned parts. Has the effect of increasing Finally, the boiler exhaust gas passes through the flue 32 to the chimney.

FIG. 4 shows a control device according to the prior art used for the boiler device shown in FIG. In summary, the control device generates a steam flow according to the load command 101, and maintains the steam temperature of the main steam line 21 and the reheat steam line 27 at a specified temperature according to the load command 101. The main focus is.

The total fuel command 107 is obtained by adding the steam temperature at the inlet of the superheater 18 detected by the temperature detector 14 to the basic value given by the function element 105 in accordance with the load command 101 and the function element 1
02 is obtained by adding the correction signal obtained by obtaining the deviation of the output of the second through the PID element 104 by the adding element 106. In other words, the total fuel amount command 107 can be said to be a configuration in which the fluctuation of the water-fuel ratio in the furnace / water wall 12 related to the fluctuation of the water supply amount or the actual flow rate of the fuel supply line 1 is corrected by PID control based on the load command.

The opening command 109 of the gas recirculation damper 29 is obtained by a function element 108 in accordance with the load command 101. This is because the heat absorption of the furnace / water wall becomes relatively large in the low load zone of the boiler, so that the gas amount in the gas recirculation line 30 is increased, and the furnace / water wall mainly composed of radiant heat transfer is used. 12 has the effect of reducing the heat absorption of the superheater 18 and the reheater 24, which are mainly composed of contact heat transfer.

The steam temperature of the main steam line 21 is determined by the command signal 1
24, the injection valve 17 is adjusted. That is, the basic signal by the function element 122, the actual temperature detected by the temperature detector 20 and the target value by the function element 119 are subtracted by the element 12
The value is compared by 0, and a correction signal obtained by giving this to the PID element 121 is added by an adding element 123 to obtain a command signal 124 for the valve 17. The temperature control of the main steam line 21 using such a desuperheater 15 has a quick response, and the reduction of the energy conversion efficiency of the plant due to this is small, so that it is conventionally used.

The temperature of the steam in the reheat steam line 27 is controlled by adjusting the amount of the heating gas in the reheater 24 according to the command signal 116.
That is, the basic signal by the function element 113, the actual temperature detected by the temperature detector 26 and the target value by the function element 110 are compared by the subtraction element 111, and the correction signal obtained by giving the result to the PID element 112 is added to the addition element. In addition to 114, an opening command signal 116 for the damper 25 is obtained by a function element 115 for correcting the opening and flow rate of the damper.

At this time, the damper 19 is
Is moved in the opposite direction to the command 116 to assist in adjusting the amount of gas passing through the reheater 24. This is superheater 1
8 disturbs the heat absorption of the main steam line 21, causing the temperature fluctuation of the main steam line 21.
There is no problem because the change in the amount of water injected into 5 can be sufficiently absorbed. As another method for controlling the reheat steam temperature, a method of injecting water into a reheater is also known. However, this method increases the steam amount of the inefficient low-pressure turbine 28 to reduce the total energy conversion efficiency. It is used only for emergency purposes.

[0013]

The boiler body shown in FIG. 3 and the boiler control device shown in FIG. 4 operate satisfactorily if the fuel property is near the design value of the boiler body. In addition, regarding the properties of fuel, heat generation, combustion rate, and ash generation are generally regarded as important, and the difference in heat generation determines the required heat of the boiler according to the load command in terms of operation control. Therefore, it is possible to adjust the flow rate of the fuel supply line 1 in inverse proportion to the calorific value. However, "difference in combustion speed" and "dirt of the heat transfer surface due to ash adhesion" bring technical problems to the boiler main body and the boiler control device of FIGS.

Here, the background of the present invention will be supplementarily described. Generally, when considering the ratio of carbon content / hydrogen content of fossil fuel contained elements, the lower the above value, the higher the burning rate. In the case of coal, an arrangement method in which the fixed carbon / volatile content ratio is defined as the fuel ratio is used. Similarly, the lower the above value is, the higher the combustion rate is. Therefore, if an example is shown, natural gas, naphtha, light oil A heavy oil,
C heavy oil, asphalt, lignite, bituminous coal, anthracite.

Particularly, in the case of coal, for example, even for bituminous coal, the fuel ratio (accordingly, the burning rate) depends on the coal-producing area (brand).
The fuel ratio tends to vary greatly depending on which part of the vein is dug, as is commonly known as “biting the stratum” even with the same brand of coal. In addition, it may contain a large amount of ash components (silica, alumina, calcium, magnesium, etc.).

It is a common sense that a fuel whose combustion speed deviates from the design value of a typical boiler, whose combustion speed varies greatly, and whose ash component is high (hereinafter referred to as low-grade fuel) are inexpensive. However, the operation of the boiler is difficult with the use of the fuel alone, and therefore, the operation is usually performed by mixing an expensive fuel with less defects (hereinafter, referred to as a high-grade fuel).

An object of the present invention is to provide a fuel mixing control device which realizes economical boiler operation by reducing the mixing of high-grade fuel as much as possible. A technical problem will be described.

For example, when a fuel having a low combustion rate is used, the distribution of the calorific value in the furnace moves to the downstream side (furnace outlet side) along the flow of the combustion gas, and the heat absorption of the water wall at the lower part of the furnace. The amount of heat greatly decreases, so the total heat absorption of the furnace decreases. Even if the furnace heat transfer surface becomes dirty, the heat absorption of the furnace decreases,
In these cases, even if the same heat input is applied, the furnace exhaust gas temperature rises because the heat is hardly absorbed by the furnace, and the downstream superheater 1
8. As the gas temperature of the reheater 24 increases, the amount of heat absorbed by these increases.

Conversely, when a fuel having a high burning rate is used,
If the dirt on the heat transfer surface is peeled off, the temperature of the furnace exhaust gas decreases, and the amount of heat absorbed by the downstream superheater 18 and reheater 24 decreases.

Therefore, the following problems occur.

(1) When the amount of heat absorbed by the water wall 12 is significantly reduced from the design value, the enthalpy of the fluid at the outlet of the water wall decreases, and in extreme cases, the steam may become wet steam containing water droplets. In such a case, a moisture separator may be required because wet steam cannot be passed through the superheater 18. In addition, since the moisture separation means a decrease in the amount of steam flowing to the superheater 18, in such a case, the steam generated by the boiler is insufficient.

Conversely, if the amount of heat absorbed by the water wall 12 becomes excessive, the metal temperature of the water wall 12 becomes high, which is dangerous. In the prior art, in order to avoid such an excessive or insufficient amount of heat absorption of the water wall 12, a high-grade fuel must always be used.

It is assumed that the boiler is controlled in the order of load, steam amount (water supply amount), and fuel amount (total heat absorption amount), and the total heat absorption amount is controlled for each load zone. The problem and the measures to be taken will be explained under the conditions.

(2) It is necessary to increase or decrease the opening of the water injection valve 17 due to an increase or decrease in the heat absorption of the superheater 18. These are caused by the deviation of the heat absorption balance between the boiler water wall 12 and the superheater from the design point, and the water injection valve 17 is likely to be always operated when the opening degree of the water injection valve 17 is fully opened or in the vicinity of the fully closed state. In the vicinity of the full opening and the full closing, there is little room for operation of one side of the opening of the water injection valve 36. In this state, if any disturbance occurs or the load command 101 is changed, the transient fluctuation of the temperature of the main steam line 21 is dealt with. In some cases, it is not possible. In the prior art, in order to avoid the above-mentioned situation, high-grade fuel must be used.

(3) It is necessary to reduce or increase the opening of the reheater gas distribution damper 25 by increasing or decreasing the heat absorption of the reheater 24. These are caused by the deviation of the heat absorption amount of the reheater 24 from the design point, and it is easy to always operate the damper 25 when the opening degree of the damper 25 is fully open or in the vicinity of fully closed. Said full opening,
In the vicinity of the fully closed position, there is little room for operation on one side of the opening degree of the damper 25, and in this state, some disturbance occurs or the load command 1
If 01 is changed, there may be cases where transient fluctuations in the temperature of the reheat steam line 27 cannot be handled. In the prior art, in order to avoid the above-mentioned situation, high-grade fuel must be used.

(4) It is necessary to increase or decrease the opening of the gas recirculation damper 29 due to the increase or decrease of the heat absorption of the water wall 12. These are due to deviations from the design of the balance between the heat absorption of the water wall 12 and the heat absorption of the superheater 18 and the reheater 24. In such a case, the function of the prior art embodiment of FIG. The setting of the element 108 needs to be changed, which is troublesome.

If the gas recirculation is insufficient, overheating of the lower part of the furnace 7 and an increase in nitrogen oxides in the combustion of the burner 4 are likely to occur, and if the gas recirculation is excessive, combustion may become unstable. Must be carefully changed, and it is likely that it is difficult to respond quickly to an increase or decrease in the heat absorption of the water wall 12. In the prior art, in order to avoid the above-mentioned situation, high-grade fuel must be used.

(5) If the temperature of the furnace exhaust gas 9 increases, it exceeds the melting point of the ash component in the fuel, and the superheater 18 and the reheater 24
The likelihood of ash entering the vicinity increases. There is no problem if the ash falls into the furnace 7, but when it enters the vicinity of the superheater 18 or the reheater 24, it cools down and adheres to its surface, causing a significant decrease in heat transfer performance or blockage. Will be possible.
In the prior art, since the situation is extremely serious, in view of lowering the temperature of the furnace exhaust gas 9, increasing the melting point of the ash in the fuel, or reducing the content of the ash itself,
We have to contend with using high-grade fuel with sufficient margin.

(6) When mixing low-grade fuel and high-grade fuel, it is desirable to operate a boiler in which the proportion of high-grade fuel is reduced as much as possible. However, low-grade fuel often varies in properties as described above. Assuming the worst properties, high-grade fuel must be used.

[0030]

In order to solve the above problems, the present invention mainly employs the following configuration.

A boiler device comprising: a furnace provided with a burner; a water cooling wall surrounding the furnace; and a superheater for heating steam generated in the water cooling wall in an exhaust gas flow path of the furnace. Detecting means for detecting the ratio of the amount of heat exchange between the water cooling wall and the superheater, a plurality of fuel supply means for supplying a plurality of fuels having different combustion speeds, and adjusting respective fuel flow rates in the fuel supply means. Fuel adjusting means, and mixing means for mixing the plurality of fuels adjusted by the fuel adjusting means and supplying the fuel to the burner;
An increase or decrease in the relative ratio of the heat exchange amount of the water-cooled wall to the superheater is detected by the detection means, and the flow rate of the plurality of fuels is adjusted based on the detection, thereby mixing the fuel having a high combustion speed. A boiler fuel mixing control device that decreases or increases the proportion, respectively.

Further, a furnace provided with a burner, a water cooling wall surrounding the furnace, a superheater for superheating steam generated in the water cooling wall in an exhaust gas flow path of the furnace, and a water injection amount to the superheater A water injection adjustment means for adjusting, and a boiler device comprising: a detection means for detecting the water injection amount; a plurality of fuel supply means for supplying a plurality of fuels having different combustion rates;
Fuel adjusting means for adjusting each fuel flow rate in the fuel supply means, mixing means for mixing the plurality of fuels adjusted by the fuel adjusting means and supplying the fuel to the burner;
Detecting the increase or decrease of the water injection amount by the detection means, and adjusting the flow rate of the plurality of fuels based on the detection, thereby increasing or decreasing the mixing ratio of the fuel having a high combustion speed, respectively. Boiler fuel mixing control device.

A furnace provided with a burner; a water cooling wall surrounding the furnace; a superheater and a reheater for superheating steam generated in the water cooling wall in an exhaust gas flow path of the furnace; A flow rate distribution adjusting means for adjusting the flow rate distribution of the exhaust gas of the furnace to the reheater, wherein the detecting means for detecting the flow rate distribution of the exhaust gas of the furnace to the reheater, A plurality of fuel supply means for supplying a plurality of different fuels; a fuel adjustment means for adjusting a fuel flow rate in the fuel supply means; and a plurality of fuels adjusted by the fuel adjustment means and supplied to the burner. Mixing means, and an increase or a decrease in the exhaust gas flow rate distribution to the reheater is detected by the detection means, and the flow rate adjustment of the plurality of fuels is performed based on the detection, whereby the combustion speed is reduced. Boiler fuel mixing control apparatus comprising mixing ratio of fuel to decrease or increase, respectively.

Further, a furnace provided with a burner, a water cooling wall surrounding the furnace, a superheater and a reheater for superheating steam generated in the water cooling wall in an exhaust gas flow path of the furnace, the superheater, Recirculation amount adjusting means for adjusting the amount of recirculation of exhaust gas passing through a reheater to the furnace, and a boiler device including: a detection means for detecting the amount of recirculation,
A plurality of fuel supply means for supplying a plurality of fuels having different combustion rates; a fuel adjustment means for adjusting a fuel flow rate in the fuel supply means; a plurality of fuels adjusted by the fuel adjustment means; Mixing means for supplying the fuel to the burner, wherein the increase or decrease in the recirculation amount is detected by the detection means, and the flow rate of the plurality of fuels is adjusted based on the detection, whereby the fuel having a high combustion rate is obtained. Boiler fuel mixing control device which decreases or increases the mixing ratio of the boiler respectively.

A boiler apparatus comprising: a furnace provided with a burner; a water cooling wall surrounding the furnace; and an exhaust gas temperature measuring means for measuring an exhaust gas temperature at the furnace outlet, wherein the boiler apparatus has a plurality of combustion speeds different from each other. A plurality of fuel supply means for supplying fuel, a fuel adjustment means for adjusting the flow rate of each fuel in the fuel supply means, and a mixing means for mixing the plurality of fuels adjusted by the fuel adjustment means and supplying the fuel to the burner And measuring the increase or decrease of the furnace exhaust gas temperature by the exhaust gas temperature measuring means, and adjusting the flow rate of the plurality of fuels based on the measurement, thereby increasing the mixing ratio of the fuel having a high combustion rate. Boiler fuel mixing control device which increases or decreases respectively.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.
This will be described below with reference to FIG. Here, 4 is a burner, 5 is an air line, 6 is a ventilator, 7 is a furnace, 8 is an air register, 9 is furnace exhaust gas, 10 is a water supply line, 11 is a pump, 12 is a water wall, and 14 is a temperature detector. , 15 is a temperature reducer, 17 is a water injection valve, 18 is a superheater, 19 is a gas damper,
20 is a temperature detector, 21 is a main steam line, 22 is a high-pressure turbine, 24 is a reheater, 25 is a gas damper, 26 is a temperature detector, 27 is a high-temperature reheat steam line, 28 is a low-pressure turbine, and 29 is recirculation. Damper, 30 is a gas recirculation line, 3
1 is a ventilator, 51 and 52 are valves, 53 is a furnace exhaust gas temperature measuring means, 54 is a fuel property analyzer, 55 is a fuel supply A system line, and 56 is a fuel supply B system line.

FIG. 1 shows a control device according to an embodiment of the present invention, and FIG. 2 shows a boiler device main body of the embodiment of the present invention. Hereinafter, the boiler apparatus body of FIG. 3 and FIG.
The same reference numerals are given to the same portions as those of the control device described above, and the description of the common components will be omitted. By the way, it will be described first that all the configurations shown in FIGS. 3 and 4 are one embodiment of the present invention, but some of all the configurations shown in FIG. This constitutes another embodiment, which will be described later.

The configuration of the boiler apparatus main body according to the present embodiment shown in FIG. 2 is different from that of FIG.
Two types of lines having different combustion speeds are provided as A system 55 and B system 56 as fuel supply lines, and the corresponding fuel flow rates can be individually adjusted by valves 51 and 52. And an on-line fuel property analyzer 54 at the entrance of the burner.

Here, the measuring means 53 is disclosed in JP-A-8-145812 and JP-A-9-17857 by the present applicant.
The acoustic gas temperature measuring device according to No. 6 is given as an example, and the acoustic gas temperature measuring device is suitable for its high accuracy and durability. In addition, the analyzer 54 uses a method of obtaining the height of the peak corresponding to each element on the spectrum by the laser-induced breakdown method (LIBS method) and obtaining the ratio of the height of hydrogen and carbon, for example. Things are an example. Details of this method are described in known, for example, Ottesen,
D. K. etal: Laser spark emis
sion spectroscopy for in
situ. Rcal-time monitoring
of pulverized coal parti
cle composition; Energy an
d Fuels, Vol. 5, No. 2, pp304-
312, 1991 and the like.

In the control device shown in FIG.
The differences are as follows. That is, the re-heater gas distribution command 178 relating to the opening degree 124 of the spray valve 17 and the opening degree of the gas damper 25 is input to the function element 155 and the function element 153, respectively, and the correction 156 relating to the spray valve opening degree and Correction 15 related to damper opening
Get 4. Then, these corrections 156 and 154
And a furnace exhaust gas temperature basic target value 152 obtained by giving the load command 101 to the function element 151.
In addition, a target value 158 of the furnace exhaust gas temperature is obtained.

Next, a difference 160 between the target value 158 and the exhaust gas temperature measured value 164 by the temperature detecting means 53 is calculated by a subtraction element 159, which is given to a PID element 161.
A fuel property target signal 186 is obtained. The fuel property may be given by the above-described ratio of carbon and hydrogen, or may be given by the fuel ratio.

Further, the target signal 186 and the fuel property measurement signal 185 are compared by a subtraction element 184, and the deviation is calculated by PI
Processed at element 187, a fuel mixture ratio command signal 188 is obtained.

At this time, the command signal 188 compensates for the non-linearity of the flow control means 51, 52, one of which is multiplied by the monotonically increasing function element 167, 171 through the monotonically decreasing function element 167, to the total fuel command signal 107. , Corresponding flow rate adjusting means 51,
52 is driven. That is, according to the command signal 188,
When the amount of fuel related to the flow rate adjusting means 51 increases, the amount of fuel related to the flow rate adjusting means 52 decreases.

Although the above description discloses all the configurations, functions, and operations of the control device shown in FIG. 1, the partial configuration of the control device shown in FIG. It has a configuration and functions and effects associated with the configuration. Hereinafter, features of the partial configuration will be described.

(1) A configuration in which the function element 155 is provided in consideration of the state of the superheater injection valve 17.

(2) A configuration in which the function element 153 is provided in consideration of the state of the reheater gas damper 25.

(3) A configuration in which the function element 151 is provided in consideration of the load command (therefore, the design value of the heat absorption distribution of the water wall 12).

(4) Considering the influence of the temperature of the furnace exhaust gas 9, the measuring means 53, the subtraction element 159, the PID element 161
Configuration to provide.

(5) A configuration in which the measuring means 54, the subtraction element 184, and the PI element 187 are provided in consideration of the influence of variations in fuel properties.

In the boiler control device, if at least one of the above five partial configurations is added to the configuration of the control device shown in FIG. 4, another embodiment of the present invention is configured. And with the adoption of the partial configuration,
The object of the present invention is to achieve the "realization of economical boiler operation in which the mixing of high-grade fuel is reduced as much as possible". Further, any of the above five partial configurations may be arbitrarily combined and applied to the control device of FIG. 4 as another embodiment of the present invention.

In practice, for example, if the fuel is inexpensive and the combustion rate is a special value, but the variation in properties is not a problem, the partial configuration (5) including the expensive measuring means 54 can be used. It is also advantageous to reduce the implementation cost of the present invention by omitting parts and configuring another embodiment of the present invention.

In the configuration shown in FIG. 1, the gas temperature target value 152, the gas temperature measurement value 164, the fuel property target value 186, and the fuel property measurement value 185 are absolute values (for example, a gas temperature of 1200.degree. Although the description is given assuming that the value is given by a ratio of 1.5 or the like, a relative value (for example, gas temperature + 10 ° C.,
(Fuel ratio -0.1 etc.). This makes it easy to change the setting of the function elements when adding or deleting the partial configuration.

Further, in order to solve the problem associated with the amount of heat absorption between the water wall and the superheater described in “Problems to be Solved by the Invention”, the heat absorption between the water wall 12 and the superheater 18 is eliminated. It is necessary to detect the amount, but there are various methods to detect this, for example, in the method obtained from the water side, the temperature of water, steam at the inlet and outlet of both the water wall and the superheater, the temperature, the pressure The enthalpy is determined, and the rising width of the enthalpy on both heat transfer surfaces may be multiplied by the flow rates of water and steam passing through both. If the flow rates of the two heat transfer surfaces are substantially equal, it is possible to detect the amount of heat absorption between the two simply by comparing the rising width of the enthalpy. Further, if the gas side, the gas temperature, the flow rate, and the specific heat are multiplied, the total energy held by the gas at the position can be known.
From the relationship between the gas holding energy at outlet 8 and the heat input to burner 4,
The amount of heat exchange on both heat transfer surfaces can be known.

In any case, if the relative ratio of the heat exchange amount between the two heat transfer surfaces is known, the ratio of the fuel having a high combustion rate can be reduced or increased when the relative ratio of the heat exchange amount of the water cooling wall 12 increases or decreases, respectively. With the increase, the object of the present invention can be achieved.

As described above, the embodiments of the present invention include those having the following structural features, functions and functions.

(1) When the relative ratio of the heat exchange amount of the water-cooled wall increases or decreases, the ratio of the fuel whose combustion speed is high is decreased or increased, respectively. In addition, the meaning of the relative ratio of the heat exchange amount of the water cooling wall means "the ratio of the heat exchange amount of the water cooling wall to the heat exchange amount of the superheater". Are naturally different from each other, and therefore, attention is paid to “relative” values in the sense that they are considered under the same load condition. The solution to the change in the relative ratio of the heat exchange amount of the water-cooled wall has the overall configuration shown in FIG. 1 and is technically understood from a different technical viewpoint from the following (2) to (6). It is an idea.

(2) When the water injection amount 16 increases or decreases, the ratio of the fuel having the higher combustion rate is increased or decreased, respectively.

(3) When increasing or decreasing the distribution of the exhaust gas flow rate to the reheater 24, the proportion of fuel having a high combustion rate is decreased or increased, respectively.

(4) When the gas recirculation amount 30 is increased (the temperature of the furnace is too high) or decreased, the proportion of fuel having a high combustion rate is decreased or increased, respectively.

(5) A means for measuring or estimating furnace exhaust gas temperature is provided to increase or decrease the proportion of fuel having a high combustion rate when the furnace exhaust gas temperature increases or decreases, respectively.

(6) A fuel property online analysis means at the burner inlet is provided, and a target value of the fuel property at the burner inlet is commanded to reduce the deviation between the measured value of the online analysis means and the target value. The mixing ratio of the plurality of fuels described above is adjusted.

The functions and functions are as follows.

(1) If the relative proportion of the heat exchange amount of the water cooling wall 12 is increased or decreased, and the proportion of the fuel having a higher combustion rate is decreased or increased, respectively, the gas temperature distribution in the furnace (and hence the heat exchange amount) Distribution) respectively move to the downstream side and the upstream side, and the relative ratio of the heat exchange amount of the water-cooling wall 12 decreases and increases to an appropriate value in comparison with the superheater 18. The change of the fuel ratio is necessary and sufficient depending on the situation.

(2) If the proportion of fuel having a high combustion rate is increased or decreased when the water injection amount 16 is increased or decreased, respectively, the center of the gas temperature distribution (accordingly, heat absorption) becomes the water wall 12 side, and The amount of heat absorbed by the superheater 18 is decreased and increased by moving to the side of the heater 18, and the deviation of the heat absorption balance between the boiler water wall 12 and the superheater from the design point is eliminated.

That is, the opening degree of the water injection valve 17 decreases and increases by the action of the PID element 121 in FIG. Can handle fluctuations with a margin. The change of the fuel ratio is necessary and sufficient depending on the situation.

(3) If the ratio of fuel having a high combustion rate is decreased or increased when the distribution of exhaust gas flow to the reheater 24 is increased or decreased, the gas temperature distribution (accordingly, heat absorption)
Move to the reheater 24 side and the water wall 12 side, respectively, the amount of heat absorption of the reheater 24 increases and decreases, respectively, and the deviation of the heat absorption of the reheater 24 from the design point is eliminated. I do.

That is, the opening degree of the damper 25 decreases and increases by the action of the PID element 112 in FIG. 4, and the opening degree of the damper 25 remains open on both the open and closed sides. Can handle fluctuations with a margin. The change of the fuel ratio is necessary and sufficient depending on the situation.

(4) When the gas recirculation amount 30 is increased or decreased, the proportion of fuel having a high combustion rate is decreased,
If it increases, the central part of the gas temperature distribution (and therefore the heat absorption) moves to the superheater 18 side and the water wall 12 side, respectively.
The amount of heat absorption on the side decreases and increases, and the deviation of the heat absorption of the water wall 12 from the design point is eliminated without making any troublesome setting change of the function element 108. The change of the fuel ratio is necessary and sufficient depending on the situation.

(5) A means for measuring or estimating the furnace exhaust gas temperature is installed, and when the furnace exhaust gas temperature increases or decreases,
By increasing or decreasing the proportion of fuel having a high combustion rate, respectively, the central part of the gas temperature distribution becomes the upstream side of the water wall 12,
It moves to the superheater 18 side (the downstream side of the water wall 12), and the temperature of the furnace exhaust gas 9 decreases and increases, respectively. Therefore, by a necessary and sufficient change according to the situation of the fuel ratio, the temperature of the furnace exhaust gas 9 is controlled to be equal to or lower than the melting point of the ash component in the fuel, and the ash enters the vicinity of the superheater 18 and the reheater 24. Danger can be eliminated.

(6) On-line analysis means for the fuel property at the burner inlet is provided, and a target value of the fuel property at the burner inlet is commanded to reduce the deviation between the measured value of the online analysis means and the target value. By adjusting the mixing ratio of the plurality of fuels described above, a high-grade coal can be mixed in a necessary and sufficient amount according to the variation in the properties of the low-grade fuel.

[0071]

According to the present invention, the following effects can be obtained.

By mixing the required minimum amount of expensive high-grade coal, the amount of heat exchange in the water wall 12 is maintained in an appropriate range, and there are serious problems such as a shortage of steam generated by the boiler and a high metal temperature of the water wall 12. Can be prevented beforehand.

By mixing the necessary minimum amount of expensive high-grade coal, transient fluctuations in the temperature of the main steam line 21 can be adequately dealt with.

By mixing the necessary minimum amount of expensive high-grade coal, transient fluctuations in the temperature of the reheat steam line 27 can be adequately dealt with.

By mixing the required minimum amount of expensive high-grade coal, the deviation of the heat absorption of the water wall 12 from the design point is eliminated without complicated setting change of the function element 108.

By mixing the necessary minimum amount of expensive high-grade coal, the danger of ash in the fuel entering the vicinity of the superheater 18 and the reheater 24 can be eliminated.

By mixing the required minimum amount of expensive high-grade coal, it is possible to solve the problems related to the variation in properties of low-grade fuel.

[Brief description of the drawings]

FIG. 1 is a diagram showing a control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a boiler device main body according to the embodiment of the present invention.

FIG. 3 is a view showing a conventional boiler apparatus main body.

FIG. 4 is a diagram showing a control device according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel line 2 Flow control means 4 Burner 5 Air line 6 Ventilator 7 Furnace 8 Air register 9 Furnace exhaust gas 10 Water supply line 11 Pump 12 Water wall 14 Temperature detector 15 Desuperheater 17 Water injection valve 18 Superheater 19 Gas damper 20 Temperature detection Apparatus 21 Main steam line 22 High pressure turbine 24 Reheater 25 Gas damper 26 Temperature detector 27 High temperature reheat steam line 28 Low pressure turbine 29 Recirculation damper 30 Gas recirculation line 31 Ventilator 51, 52 Valve 53 Furnace exhaust gas temperature measuring means 54 Fuel property analyzer 55 Fuel supply A system line 56 Fuel supply B system line

Continued on the front page (72) Inventor Shunichi Tsumura 6-9 Takaracho, Kure City, Hiroshima Pref. Babcock Hitachi Kure Factory

Claims (6)

[Claims] 1. A boiler apparatus comprising: a furnace provided with a burner; a water cooling wall surrounding the furnace; and a superheater for heating steam generated in the water cooling wall in an exhaust gas flow path of the furnace. Detecting means for detecting the ratio of the amount of heat exchange between the water cooling wall and the superheater; a plurality of fuel supply means for supplying a plurality of fuels having different combustion rates; and a fuel flow rate in the fuel supply means. A fuel adjusting means for adjusting, and a mixing means for mixing the plurality of fuels adjusted by the fuel adjusting means and supplying the fuel to the burner, wherein a relative ratio of a heat exchange amount of the water cooling wall to the superheater is set. The increase or decrease is detected by the detection means, and the flow rate of the plurality of fuels is adjusted based on the detection to reduce or increase the mixing ratio of the fuel having a high combustion speed. Boiler fuel mixing control apparatus according to claim. 2. A furnace provided with a burner, a water cooling wall surrounding the furnace, a superheater for superheating steam generated in the water cooling wall in an exhaust gas flow path of the furnace, and a water injection amount to the superheater. A water injection adjusting means for adjusting the water injection amount, a detecting means for detecting the amount of injected water, a plurality of fuel supply means for supplying a plurality of fuels having different combustion speeds, and each of the fuel supply means A fuel adjusting means for adjusting a fuel flow rate; and a mixing means for mixing the plurality of fuels adjusted by the fuel adjusting means and supplying the fuel to the burner, wherein the detecting means detects an increase or decrease in the water injection amount. A boiler fuel mixing control device for detecting and adjusting the flow rate of the plurality of fuels based on the detection to increase or decrease the mixing ratio of the fuel having a high combustion speed, respectively. 3. A furnace provided with a burner, a water cooling wall surrounding the furnace, a superheater and a reheater for superheating steam generated in the water cooling wall in an exhaust gas passage of the furnace, and the reheater. A flow rate distribution adjusting means for adjusting a flow rate distribution of the exhaust gas from the furnace to the reheater, wherein a detecting means for detecting a flow rate distribution of the exhaust gas from the furnace to the reheater; A plurality of fuel supply means for supplying a plurality of different fuels; a fuel adjustment means for adjusting respective fuel flow rates in the fuel supply means; and a plurality of fuels adjusted by the fuel adjustment means mixed and supplied to the burner. Mixing means for detecting the increase or decrease of the exhaust gas flow rate distribution to the reheater by the detection means, and adjusting the flow rate of the plurality of fuels based on the detection, thereby increasing the combustion speed. Boiler fuel mixing control apparatus characterized by decreased or increased respectively mixing ratio of the fuel that. 4. A furnace provided with a burner, a water cooling wall surrounding the furnace, a superheater and a reheater that superheats steam generated in the water cooling wall in an exhaust gas flow path of the furnace, A recirculation amount adjusting means for adjusting an amount of recirculation of the exhaust gas passing through a reheater to the furnace, wherein the detection means detects the amount of recirculation, and a plurality of different combustion speeds A plurality of fuel supply means for supplying the same fuel; a fuel adjustment means for adjusting a fuel flow rate in the fuel supply means; and a mixture for mixing the plurality of fuels adjusted by the fuel adjustment means and supplying the fuel to the burner. Means for detecting the increase or decrease in the recirculation amount by the detection means, and adjusting the flow rate of the plurality of fuels based on the detection, thereby increasing the mixing ratio of the fuel having a high combustion rate. Boiler fuel mixing control apparatus characterized by being reduced or increased. 5. A boiler device comprising: a furnace provided with a burner; a water cooling wall surrounding the furnace; and an exhaust gas temperature measuring means for measuring an exhaust gas temperature at the furnace outlet. A plurality of fuel supply means for supplying fuel; a fuel adjustment means for adjusting respective fuel flow rates in the fuel supply means; and a mixing means for mixing the plurality of fuels adjusted by the fuel adjustment means and supplying the fuel to the burner. By measuring the increase or decrease of the furnace exhaust gas temperature by the exhaust gas temperature measuring means, and adjusting the flow rate of the plurality of fuels based on the measurement, the mixing ratio of the fuel having a high combustion rate A boiler fuel mixing control device characterized by increasing or decreasing respectively. 6. The boiler fuel mixing control device according to claim 1, further comprising an analysis unit configured to analyze a fuel property at an inlet of the burner, wherein a target fuel property at the burner inlet is provided. A boiler fuel mixture control device, wherein the mixture ratio of the plurality of fuels is adjusted so as to reduce a deviation between the measurement value of the analysis means and the target value.