JP2006200875A - Determination method of boiler fuel input amount - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a determination method of a boiler fuel input amount capable of performing correction into a proper fuel input amount to a boiler considering a change of boiler efficiency on the basis of values after the feedback correction and before the correction, suppressing excessive input of fuel to the boiler, and, for example, allowing suppression of reduction of heat efficiency of the boiler or increase of an exhaust gas amount from the boiler. <P>SOLUTION: In this method correcting the fuel input amount to the boiler, the fuel input amount supplied to the boiler is found by an input requirement load amount A, the fuel is supplied to the boiler correspondingly to the input amount, a steam pressure generated in the boiler is measured, and a feedback correction amount is found from the measured steam pressure and a set steam pressure. In the method, a plurality of ratios or differences between the value after the feedback correction and the value before the correction are stored while sequentially updating the ratio or the difference, a fuel correction coefficient is found from the plurality of stored values, and the value after the feedback correction is corrected by the correction coefficient. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method of correcting an amount of fuel input to a boiler and determining an appropriate fuel amount according to a required load amount of the boiler.

Conventionally, for example, power generation using a boiler facility is generated by supplying fuel (solid fuel, gas fuel, or liquid fuel) to a boiler (furnace) and burning it, and absorbing the heat with a heat exchanger The steam is supplied to a turbine and output from a generator (for example, see Patent Document 1). Note that the amount of fuel input to the boiler is determined by a preset relational expression (shown below as a general expression) based on a function of the required load amount (for example, the required steam amount) and the fuel input amount to the boiler. The
Y = ∫ (k · X)
Here, Y is the amount of fuel input, X is the required load, and k is a value determined by the boiler efficiency (boiler thermal efficiency) and the unit conversion value.

However, when using this boiler, the boiler efficiency fluctuates due to, for example, dirt on the heat transfer surface of the boiler, fuel properties, and other factors. The required steam volume could not be obtained. For this reason, for example, the amount of power generated by the generator, the main steam pressure generated by the boiler, and the fuel supply flow rate to the boiler fluctuated with respect to the target value.
Therefore, fuel is supplied to the boiler corresponding to the fuel input amount obtained using the above relational expression, the main steam pressure generated in the boiler is measured, and PID control is performed from the measured main steam pressure and the set main steam pressure. In general, a method is used in which the feedback correction amount is obtained by adding the feedback correction amount to the required load amount to correct the fuel injection amount to the boiler.

JP-A-9-250734

However, since the heat capacity of the boiler used is large, it takes a long time from the adjustment of the fuel input amount to the boiler to the occurrence of a change in the main steam pressure. For this reason, in the conventional feedback control, the PID gain (PID correction width) is increased to improve the follow-up of the fuel input amount with respect to the main steam pressure fluctuation.
In this way, by increasing the gain of PID feedback control, for example, the actual thermal efficiency change of the boiler equipment becomes significant due to the contamination of the boiler heat transfer surface by combustion ash using coal as fuel, and the preset boiler efficiency A difference arises.
As a result, for example, the follow-up control of the fuel input amount when the boiler load is changed or when the fuel property (calorie) changes is deteriorated (large hunting occurs), and the fuel is excessively injected into the boiler (excessive or excessive fuel input amount). For example, the amount of exhaust gas from the boiler increases or the thermal efficiency of the boiler decreases.

The present invention has been made in view of such circumstances, and based on the values after feedback correction and before correction, it can be corrected to an appropriate fuel injection amount to the boiler in consideration of changes in boiler efficiency, and fuel is excessively input to the boiler. It is an object of the present invention to provide a boiler fuel input amount determination method that can suppress an increase in the amount of exhaust gas from the boiler or a decrease in the thermal efficiency of the boiler.

According to the first aspect of the invention, the boiler fuel input amount determining method determines the fuel input amount to be supplied to the boiler based on the input required load amount, and supplies fuel to the boiler corresponding to the determined fuel input amount. In addition, the steam pressure generated in the boiler is measured, the feedback correction amount is obtained from the measured steam pressure and the set steam pressure, and the fuel input amount to the boiler is corrected by the feedback correction amount.
A plurality of ratios or differences between values after feedback correction and before correction are sequentially updated and stored, a fuel correction coefficient is obtained from the stored values, and the value after feedback correction is corrected by the fuel correction coefficient.

According to the second aspect of the invention, the boiler fuel input amount determining method determines the fuel input amount to be supplied to the boiler based on the input required load amount, and supplies fuel to the boiler corresponding to the determined fuel input amount. In addition, the steam pressure generated in the boiler is measured, the feedback correction amount is obtained from the measured steam pressure and the set steam pressure, and the fuel input amount to the boiler is corrected by the feedback correction amount.
A plurality of ratios or differences between the required load amount B of the boiler after feedback correction and the input required load amount A of the boiler before feedback correction are sequentially updated, and a fuel correction coefficient is calculated from the stored values. The fuel injection amount to the boiler calculated from the required load amount B after the feedback correction is corrected by the fuel correction coefficient.

According to the third aspect of the invention, the boiler fuel input amount determining method determines the fuel input amount to be supplied to the boiler based on the input required load amount, and supplies fuel to the boiler corresponding to the determined fuel input amount. In addition, the steam pressure generated in the boiler is measured, the feedback correction amount is obtained from the measured steam pressure and the set steam pressure, and the fuel input amount to the boiler is corrected by the feedback correction amount.
A plurality of ratios or differences between the required load amount B of the boiler after feedback correction and the input required load amount A of the boiler before feedback correction are sequentially updated, and a fuel correction coefficient is calculated from the stored values. And the input required load amount A or the required load amount B is corrected by the fuel correction coefficient.

According to the fourth aspect of the present invention, the boiler fuel input amount determining method determines the fuel input amount to be supplied to the boiler based on the input required load amount, and supplies fuel to the boiler corresponding to the determined fuel input amount. In addition, the steam pressure generated in the boiler is measured, the feedback correction amount is obtained from the measured steam pressure and the set steam pressure, and the fuel input amount to the boiler is corrected by the feedback correction amount.
While sequentially updating the ratio or difference between the fuel input amount B obtained from the required load amount B of the boiler after feedback correction and the fuel input amount A obtained from the input required load amount A of the boiler before feedback correction. A plurality of stored values, a fuel correction coefficient is obtained from the stored plurality of values, and the fuel injection amount B is corrected with the fuel correction coefficient.

Here, in the determination method of the boiler fuel input amount according to the fourth invention, when the fuel correction coefficient is obtained based on a ratio or difference between the values of the fuel input amount B and the fuel input amount A, the obtained fuel It is preferable to correct the input required load amount A with a correction coefficient.

According to the fifth aspect of the present invention, the boiler fuel input amount determining method determines the fuel input amount to be supplied to the boiler based on the input required load amount, and supplies fuel to the boiler corresponding to the determined fuel input amount. And, further, measuring the steam pressure generated in the boiler, obtaining a feedback correction amount from the measured steam pressure and the set steam pressure, after converting the input required load amount to the boiler into the fuel input amount, In the method of correcting the fuel injection amount to the boiler with this feedback correction amount,
A plurality of ratios or differences between the fuel injection amount after feedback correction and the fuel input amount before correction are sequentially stored, a fuel correction coefficient is obtained from the stored multiple values, and the fuel input amount after the feedback correction is calculated based on the fuel correction coefficient. Any one of the fuel input amount before the feedback correction and the input required load amount is corrected.

Here, in the method for determining the boiler fuel input amount according to the first to fifth inventions, when the ratio between the values after the feedback correction and before the correction is used as the fuel correction coefficient, the ratio of the values obtained in advance. When the difference between the values to be updated is sequentially multiplied and stored, and the difference between the values after the feedback correction and before the correction is used, the difference between the values to be updated is sequentially added to the difference between the values obtained in advance and stored. The fuel correction coefficient is preferably obtained from the stored value.

In the boiler fuel input amount determination method according to the first to fifth aspects of the invention, the fuel correction coefficient is stored by averaging the ratio or difference between the values after the feedback correction and before the correction, by means of successive moving averages. It is preferable to obtain from the values obtained.

In the boiler fuel input amount determination method according to the first to fifth inventions, the update timing of the value after the feedback correction and before the correction may be determined based on the reaction time of the fuel supplied to the boiler. preferable.

Since the present invention uses values after feedback correction and before correction, it is possible to successively perform corrections taking into account changes in the current boiler efficiency and determine an appropriate fuel injection amount to the boiler. In addition, since a plurality of ratios or differences between values after feedback correction and before correction are sequentially updated and stored, a difference with respect to a preset change in boiler efficiency is eliminated, and a fluctuation range of hunting of the fuel input amount caused by this difference is obtained. It can be suppressed than before.
As a result, it is possible to suppress excessive fuel injection into the boiler, for example, to suppress an increase in the amount of exhaust gas from the boiler or a decrease in the thermal efficiency of the boiler.

In particular, a ratio or difference between values before and after feedback correction is used as a fuel correction coefficient, and a ratio of values to be updated to a previously obtained value ratio is sequentially multiplied, or a difference between values to be updated to a previously obtained value difference is calculated. In the case of sequentially adding and storing, there is no need to manage a large amount of data, and for example, the capacity of the storage means for storing data can be reduced.

Further, it is preferable to obtain the fuel correction coefficient from the value obtained by successively moving and averaging the ratio or difference between the values after the feedback correction and before the correction because the control accuracy is improved.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIG. 1 is an explanatory diagram of a boiler fuel input amount determining method according to the first embodiment of the present invention, FIG. 2 is an explanatory diagram of an arithmetic unit that uses the boiler fuel input amount determining method, and FIG. Is an explanatory diagram of a calculation flow of the calculation device, FIG. 4 is a flow chart of a program calculation unit of the calculation flow, and FIGS. 5 to 8 are diagrams for determining a boiler fuel input amount according to first to fourth modifications, respectively. FIG. 9 is an explanatory diagram of a boiler fuel input amount determining method according to the second embodiment of the present invention, and FIG. 10 is an explanatory diagram of a boiler fuel input amount determining method according to a fifth modification. .

The boiler fuel input amount determination method according to the first embodiment of the present invention is applied to the boiler facility 10 as shown in FIGS. 1 and 2, and the required steam amount (required load amount) of the boiler. ) Using a preset fuel function F1 (hereinafter also simply referred to as a set fuel function F1) based on the relationship of fuel (for example, coal) input to the boiler corresponding to The ratio or difference between the input required steam amount A (input required load amount) and the required steam amount B (required load amount) after pressure correction (after feedback correction) is sequentially updated and stored. In this method, a fuel correction coefficient is obtained from the ratio or difference, and the fuel input amount is corrected by the fuel correction coefficient. This will be described in detail below.

First, an outline of a method for determining the boiler fuel input amount will be briefly described with reference to FIG.
In the method for determining the boiler fuel input amount of the present invention, the set fuel function F1 resulting from the change in the boiler efficiency is considered in consideration of the current boiler efficiency based on the feedback correction amount (difference between the values before and after the correction). In this method, the fuel correction coefficient is sequentially corrected so as to obtain an appropriate fuel function F1 (as if the fuel function F1 was rewritten in the online state). The general formula of the fuel function F1 is represented by the above-described Y = ∫ (k · X), where k represents the boiler efficiency.
Thus, the fuel input amount P1 obtained from the appropriate fuel function F1 and the required steam amount is changed to the fuel input amount P3 obtained from the change in the boiler efficiency k to the fuel input amount P2 obtained from the set fuel function F1 and the required steam amount. It becomes the amount that added. Therefore, by supplying the boiler with the fuel input amount P1 obtained from the appropriate fuel function F1, a main steam pressure is generated by adding the main steam pressure corresponding to the deviation to the boiler steam request amount corresponding to the load output.

As described above, since the fuel input amount hunts, if the set fuel function F1 is corrected only for each feedback correction amount, a difference in the hunting fluctuation range is included. Therefore, in order to eliminate the difference in the fluctuation range of hunting, a plurality of past feedback correction amounts (differences between values before and after correction) are also stored, and the moving average, multiplication, Or add and use.
In FIG. 1, for convenience of explanation, the relational expression between the required steam quantity and the fuel input quantity is a straight line. However, the relational expression is usually a curve according to the characteristics of the boiler.
Hereinafter, a method for correcting the fuel input amount obtained by the set fuel function F1 with the fuel correction coefficient will be described in detail.

As shown in FIG. 2 and FIG. 3, in order to always output the necessary power generation amount by the generator, the boiler required load amount (command) corresponding to the generator output is obtained at the operation unit of the boiler facility 10, that is, Input the required steam volume A. Then, the fuel input amount calculation unit 20 that has set and input the fuel function F1 determines the fuel input amount to be supplied to the boiler by the input required steam amount A to the boiler and the set fuel function F1. Supplied to the boiler. Next, the pressure of steam generated in the boiler is measured by, for example, a pressure gauge provided in the boiler, and the pressure is input to the main steam pressure transmitter P. Based on the measured main steam pressure input to the main steam pressure transmitter P, the main steam pressure correction manipulated variable is set by the PID control unit 11.

In the PID control unit 11, for example, if the fuel function F1 is obtained under the condition that the boiler state (contamination of the heat transfer surface, etc.), the fuel property, and other factors are maintained, the set value and the actual operation value Therefore, the required generator output can be obtained from the fuel function F1.
However, as described above, for example, a pressure difference (also referred to as a feedback correction amount) between the measured main steam pressure and the set main steam pressure with changes in boiler conditions, fuel properties, and other factors of the boiler equipment 10. appear.

When a pressure difference occurs between the measured main steam pressure and the set main steam pressure in the PID control unit 11, first, the deviation (error amount) of the main steam pressure generated due to excess or shortage of fuel in the adding unit 12 is calculated as the input required steam amount. Add to A.
Next, the dividing unit 13 uses the input required steam amount A (MWi) to the boiler before pressure correction as the denominator and the required steam amount B (MWii) after pressure correction as the numerator, and the input required steam amount A (MWi). And a required steam amount B (MWii), that is, a coefficient reference value (Ki) is calculated.
(MWii) / (MWi) ⇒ (Ki)

The calculated coefficient reference value (Ki) is input to the program calculation means 14.
In the program calculation means 14, as shown in FIG. 3, the coefficient reference value (Ki) input by the primary delay correction unit 15 is used to suppress transient fluctuation due to the primary delay of 10 seconds ( In order to suppress hunting), this coefficient reference value is corrected for first order lag. Thereby, the noise contained in the coefficient reference value (Ki) can be cut, and the accuracy of the corrected coefficient reference value can be improved.
(Ki) ⇒ (Ki1)
Further, the moving average calculation unit 16 of the program calculation means 14 calculates the coefficient average value (Kiε) by moving average the coefficient reference values for 30 seconds including the corrected coefficient reference value (Ki1).
(Ki1) ⇒ (Kiε)

The coefficient average value (Kiε) obtained by the above method is input to the program (PRG) calculation unit 17 of the program calculation means 14. The input required steam amount A (MWi) is also input to the program calculation unit 17.
The program calculation unit 17 uses the calculated coefficient average value (Kiε) to calculate an appropriate correction value (Kipp) for the previous stage of the fuel correction coefficient. The program calculation unit 17 can also reset the coefficient and set the calculation start (coefficient reset trigger, calculation start trigger).
Hereinafter, a method for calculating the appropriate correction value (Kipp) will be described with reference to FIG.

First, in step 1 (ST1), the operator uses the operation unit (not shown) of the arithmetic unit to give the program arithmetic unit 17 the maximum boiler load (MWt: setting constant) and partial load (MWx: setting constant). ) And the minimum load (MWm: set constant).
Next, the current input load factor, minimum load factor, and partial load factor are obtained by dividing the input required steam amount A, minimum load, and partial load of the boiler that are input in advance by the maximum load, respectively. Many partial load factors can be installed.
(MWi) / (MWt) = (MWr) ⇒Current load factor (MWm) / (MWt) = (MWmr) ⇒Minimum load factor (MWx) / (MWt) = (MWxr) ⇒Partial load factor

And the difference of the calculated | required present load factor, the minimum load factor, and a partial load factor is each calculated | required.
(MWr)-(MWmr)
(MWr)-(MWxr)
The difference between the current load factor and the constant 1 input to the program calculation unit 17 is also obtained.
(MWr) -1
This constant 1 is the maximum load factor.

In step 2 (ST2), one side (condition B) of a criterion for determining whether or not to update the input coefficient average value (Kiε) is determined according to the magnitude of the pressure deviation.
Here, if the pressure deviation does not occur in the input coefficient average value, it is 1.0, and the input coefficient average value is used within the allowable range where the pressure deviation is less than 0.99 and less than 1.01. Even if there is no problem, the coefficient average value is not updated. On the other hand, if the input coefficient average value is 0.99 ≧ Kiε, or 1.01 ≦ Kiε, it indicates that a large pressure deviation has occurred. It is necessary to update the coefficient average value with a new coefficient average value.
The coefficient average value is also set according to other conditions (option). For example, when the input steam amount (power generation load) is changed, the coefficient average value (Kiε) exceeds 0.99 and is 1 Even within the allowable range of less than .01, the update condition of the coefficient average value is satisfied.

Since {(MWr)-(MWmr)}, {(MWr)-(MWxr)}, and {(MWr) -1} obtained in step 1 are processed in substantially the same manner, { Only (MWr)-(MWxr)} will be described.
First, the obtained numerical value of {(MWr) − (MWxr)} is set as x2.
If the set x2 is −r2 ≦ x2 ≦ + r2 (r2 = 0.1) in step 3 ′ (ST3 ′), the process proceeds to the next step 4 ′ (ST4 ′). Here, if x2 does not satisfy the above condition range, this processing is terminated (END).
In step 4 ', if the condition satisfying the condition of step 3' is not continued stably, that is, if the reaction time of the fuel supplied to the boiler (here, 5 minutes) has not elapsed, step 3 ' Return to. On the other hand, if the stable state is continued for 5 minutes and the condition A is satisfied, and Kiε has deviated from the allowable value as described above, or if the trigger reset signal is satisfied and the condition B is satisfied, the input is set. As the trigger signal (digital command) of y2 of y1 to y3, the above-described coefficient average value Kiε (a ratio of newly obtained values) is multiplied by the existing coefficient Kiεx (a ratio of previously obtained values) in the memory and updated. save. Here, the reaction time is determined based on the time required from the adjustment of the fuel input amount to the boiler to the occurrence of a change in the main steam pressure.

Note that {(MWr)-(MWmr)} and {(MWr) -1} are the same as step 3 'as x1 and x3, respectively, in step 3 (ST3) and step 3 "(ST3"). Processing (r1 and r3) is performed, and subsequently processing of step 4 (ST4) and step 4 ″ (ST4 ″), which is the same processing as step 4 ′, is performed. As a result, the condition A and the condition B are satisfied, {(MWr) − (MWmr)} is a trigger signal (digital command) for y1, and the coefficient average value Kiε is the existing coefficient Kiε1 in the memory. Multiply to and save the update. Similarly, {(MWr) −1} is used as a trigger signal (digital command) for y3, the above-mentioned coefficient average value Kiε is multiplied by the existing coefficient Kiε3 in the memory, and the update is stored.

Here, when (Kiεx), which is a partial load, is considered, that is, the appropriate correction value (Kipp) can be calculated using three or more points (Kiε1), (Kiεx), and (Kiε3).
Each initial value (initialization) of (Kiε1), (Kiεx), and (Kiε3) described above is 1.
Using these numerical values, a coefficient calculation calculation is performed in step 5 (ST5) to calculate an appropriate correction value (Kipp).
Here, when there is no partial load, an appropriate correction value (Kipp) can be obtained from two points (Kiε1) and (Kiε3). An arithmetic expression for calculating an appropriate correction value (Kipp) using these two points is shown below.
{(Kiε3) − (Kiε1)} / {1- (MWmr)} · {(MWr) − (MWmr)} + (Kiε1) = (Kipg)

Further, as Kiεx which is a partial load, Kiεx1, Kiεx2, and Kiεx3 are used, and an arithmetic expression for calculating an appropriate correction value (Kipg) from a total of five points using (Kiε1) and (Kiε3) described above is used. It is shown below. The partial load factors of (Kiεx1), (Kiεx2), and (Kiεx3) are (MWxr1), (MWxr2), and (MWxr3), respectively.
When MWr <MWmr: (Kipp) = (Kiε1)
When MWmr ≦ MWr <MWxr1: (Kipp) = {(Kiεx1) − (Kiε1)} / {(MWxr1) − (MWmr)} · {(MWr) − (MWmr)} + (Kiε1)
When MWxr1 ≦ MWr <MWxr2: (Kipp) = {(Kiεx2) − (Kiεx1)} / {(MWxr2) − (MWxr1)} · {(MWr) − (MWxr1)} + (Kiεx1)
When MWxr2 ≦ MWr <MWxr3: (Kipp) = {(Kiεx3) − (Kiεx2)} / {(MWxr3) − (MWxr2)} · {(MWr) − (MWxr2)} + (Kiεx2)
When MWxr3 ≦ MWr <1.0: (Kipp) = {(Kiε3) − (Kiεx3)} / {1.00− (MWxr3)} · {(MWr) − (MWxr3)} + (Kiεx3)
When 1.0 ≦ MWr: (Kipg) = (Kiε3)

The appropriate value of the partial load is derived by the above composite operation. The partial load (Kiεx) can be increased to infinity as necessary. Thereby, the precision of the appropriate value of partial load can further be improved.
As described above, an appropriate correction value (Kipp) corresponding to the current load is obtained using (Kiε).
(Kiε) ⇒ (Kipp)

As shown in FIG. 3, the appropriate correction value (Kipp) obtained in step 5 is determined by the change rate limiting unit 18 of the program calculation means 14 in consideration of a sudden change in the operation state of the boiler facility 10. Provide a rate of change limit (eg, 0.02 / min).
Thereby, a fuel correction coefficient (Kippgε) is obtained.
(Kipp) ⇒ (Kippgε)
Note that a constant 1 is used instead of the fuel correction coefficient (Kippgε) at the time of system abnormality (error) and initialization (initial setting).

The multiplication unit 19 multiplies the corrected fuel input amount (Fueli) obtained from the set fuel function F1 and the required steam amount B after pressure correction by a fuel correction coefficient to bring it closer to the fuel input amount before correction. An appropriate fuel input amount corresponding to a main steam pressure, that is, a corrected fuel input amount (Fuelii) is obtained. Here, the corrected fuel input amount is obtained by the fuel input amount calculation unit 20.
(Kipgε) · (Fueli) = (Fuelii)
When the constant 1 is used instead of the calculated fuel correction coefficient (Kippgε), the corrected fuel input amount (Fuelii) is determined by the following equation.
1 · (Fueli) = (Fueli) = (Fuelii)
Fuel is supplied to the boiler by the determined amount of fuel input, and the required main steam pressure is obtained to obtain the amount of power generation. In addition, after supplying the obtained fuel input amount to the boiler, the main steam pressure of the boiler is measured, and the above-described procedure is repeated with this measured main steam pressure.

The above fuel correction coefficient is calculated every time the above conditions A and B are satisfied, that is, when the input steam amount is changed or whenever the coefficient average value (Kiε) deviates from the allowable range. It is preferable to update with the fuel correction coefficient newly obtained by the above. As described above, by correcting the fuel input amount using the updated fuel correction coefficient, it is possible to further suppress the variation in the power generation amount.
Further, while the change in the input required steam amount A accompanying the change in the power generation amount is continued, it is preferable to use the fuel correction coefficient as it is without updating, and update the fuel correction coefficient after the change in the input required load amount A is completed. . Thereby, the dispersion | variation in electric power generation amount can further be suppressed, without increasing a fluctuation factor.

By the above method, for example, it is possible to eliminate the follow-up delay in changing the required input load when the boiler load is changed or when the fuel property is changed, and the fluctuation range of the hunting of the fuel input amount can be suppressed as compared with the conventional method.
Here, even when the fuel input amount deviates from a preset appropriate value due to, for example, various fuel distributions and calorie changes, the relationship between the required steam amount and the fuel input amount can always be maintained at an appropriate value. Accordingly, the amount of addition due to the main steam pressure deviation (operation amount) can be reduced, and a stable and appropriate fuel can be supplied.
In addition, since the correction value addition due to the main steam pressure is almost eliminated as described above, the correction addition operation based on proportionality, differentiation, and integration, that is, the calculation operation by the PID control unit can be reduced. And under). In addition, the power generation load can be stabilized.

Furthermore, it is possible to eliminate the occurrence of excessive fuel injection and deviation correction addition of the main steam pressure.
The influence of the surplus fuel on the amount of steam (other factors) and the useless steam fluctuation due to the difference in the appropriate fuel are eliminated, and the fuel over-injection is also eliminated, leading to a reduction in the running cost of the boiler. In addition, the main steam pressure deviation (operating amount) is always equal to zero, and the main fuel injection command amount is not affected by fluctuations in the main steam pressure, improving the boiler's main steam pressure stability and combustion efficiency. It leads to.
In particular, the unit calorie (J / m ³ , J / ton) of the fuel used in the boiler is not set to an appropriate unit calorie (that is, equivalent to X of the fuel function F1) (for example, unit calorie fluctuation of coal) However, it can be corrected to an appropriate fuel function F1.
Therefore, since the amount of exhaust gas generated at the time of fuel combustion is reduced as over-injection of the fuel input is resolved, at the present time when exhaust gas regulations are advancing, operations suitable for environmental conservation can be performed.

Next, a boiler fuel input amount determination method according to a modification of the first embodiment will be described below with reference to FIGS.
(First modification)
In the determination method of the boiler fuel input amount shown in FIG. 5, the fuel correction coefficient is calculated by calculating the required steam amount B (required load amount B) after pressure correction (after feedback correction) and before pressure correction (feedback correction) shown in FIG. This is a method of correcting the required steam amount B after correction by using the ratio or difference with the required steam amount A (input required load amount A) to the boiler in the previous), using the obtained fuel correction coefficient.

Here, when the ratio of the required steam amount B obtained by the dividing unit 13 and the input required steam amount A is used for the calculation of the fuel correction coefficient, the program arithmetic unit 17 of the above-described program arithmetic means 14 uses the coefficient average value. Kiε (ratio of newly obtained values) is sequentially multiplied by the existing coefficient Kiεx (ratio of previously obtained values) in the memory and updated and stored. And the fuel correction coefficient calculated | required from this is multiplied by the required steam quantity B in the multiplication part 21. FIG.
Further, when the difference between the required steam amount B and the input required steam amount A is used for calculating the fuel correction coefficient, the program calculation unit 17 sequentially adds the coefficient average value Kiε to the existing coefficient Kiεx in the memory and updates and saves it. To do. Then, the obtained fuel correction coefficient is added to the required steam amount B by an adding unit used instead of the multiplying unit 21.

In calculating the fuel correction coefficient, instead of the required steam quantity B after pressure correction, the required steam quantity B ′ obtained by multiplying the fuel correction coefficient before update shown by the one-dot chain line in FIG. 5 is used. Is also possible. In this case, the program calculation unit 17 obtains a moving average using the obtained coefficient average value Kiε and a plurality of existing coefficients Kiεx in the memory. Then, the obtained fuel correction coefficient is multiplied by the required steam amount B multiplied by the pre-update fuel correction coefficient in the multiplier 21.
Further, when the difference between the required steam amount B ′ and the input required steam amount A is used for calculating the fuel correction coefficient, addition is performed by the adding unit instead of the multiplying unit 21.

(Second modification)
6 determines the ratio or difference between the required steam amount B after pressure correction and the required steam amount A input to the boiler before pressure correction shown in FIG. Is used to correct the input required steam amount A (input required load amount A) before pressure correction using the obtained fuel correction coefficient.
Here, when the ratio of the required steam amount B obtained by the dividing unit 13 and the input required steam amount A is used for calculation of the fuel correction coefficient, the above-described program calculation unit 17 sets the coefficient average value Kiε in the memory. The coefficient Kiεx is sequentially multiplied and saved. And the fuel correction coefficient calculated | required from this is multiplied by the input required vapor | steam amount A before pressure correction in the multiplication part 22. FIG.
Further, when the difference between the required steam amount B and the input required steam amount A is obtained and used by the subtracting unit used instead of the dividing unit 13 for calculation of the fuel correction coefficient, the above-described program calculating unit 17 uses the coefficient The average value Kiε is sequentially added to the existing coefficient Kiεx in the memory and updated and stored. Then, the obtained fuel correction coefficient is added to the input required steam amount A before pressure correction by an adding unit used instead of the multiplying unit 22.

In calculating the fuel correction coefficient, it is also possible to use the input required steam amount A ′ before pressure correction indicated by the one-dot chain line in FIG. 6 instead of the input required steam amount A before pressure correction. In this case, since the required steam amount B after the pressure correction is a value obtained by multiplying the fuel correction coefficient before the update, the above-described program arithmetic unit 17 uses the obtained coefficient average value Kiε and a plurality of existing coefficients Kiεx in the memory. Use to find the moving average. The obtained fuel correction coefficient is multiplied by the input required steam amount A by the multiplier 22.
In addition, when the difference between the required steam amount B and the input required steam amount A ′ is used for calculating the fuel correction coefficient, the addition unit performs addition instead of the multiplication unit 22.
In the method for determining the boiler fuel input amount shown in FIGS. 5 and 6 above, the required steam amount is corrected using the fuel correction coefficient obtained using the required steam amount. Correction of only the axis of the steam amount is performed, and the correction accuracy can be improved.

(Third Modification)
In the determination method of the boiler fuel input amount shown in FIG. 7, the fuel correction coefficient is calculated by inputting the fuel input amount B after pressure correction (after feedback correction) and before pressure correction (before feedback correction) obtained by the divider 13. This is a method of using a ratio with the fuel input amount A obtained from the required steam amount A.
The fuel input amount B after pressure correction is the fuel input amount obtained from the fuel function F1 and the required steam amount B, and the coefficient average value Kiε is stored in the memory as in the program calculation shown in FIGS. This is the value before multiplying by the fuel correction coefficient calculated from the value obtained by multiplying the coefficient Kiεx.
For calculating the fuel correction coefficient, instead of the fuel injection amount B after pressure correction, the fuel injection amount B ′ obtained by multiplying the fuel correction coefficient before update shown by the one-dot chain line in FIG. Can also be used. In this case, the program calculation unit 17 obtains a moving average using the obtained coefficient average value Kiε and a plurality of existing coefficients Kiεx in the memory. Then, the obtained fuel correction coefficient is multiplied by the fuel injection amount B after pressure correction by the multiplication unit 19.

When calculating the fuel correction coefficient, when using the difference between the fuel input amount after pressure correction and the fuel input amount obtained from the input required steam amount A, as in the first modified example, the multiplier unit is used. Instead of 19, addition is performed by the adding unit.
Then, instead of the fuel input amount B after the pressure correction, the fuel input amount B is divided by using the steam amount obtained by using the inverse function of the fuel function F1 (the x axis and the y axis are reversed). It is also possible to obtain the ratio. In this case, instead of the fuel input amount obtained from the input required steam amount A, the input required steam amount A is used as it is.
In this boiler fuel input determination method, the fuel input is corrected using the fuel correction coefficient obtained by using the fuel input, so that only the fuel input axis of the fuel function is corrected as a result. The correction accuracy can be improved.

(Fourth modification)
The boiler fuel input amount determination method shown in FIG. 8 uses the ratio of the fuel input amount B after pressure correction and the fuel input amount A to the boiler before pressure correction shown in FIG. 7 to calculate the fuel correction coefficient. In this method, the required input steam amount A (input required load amount A) before pressure correction is corrected by the obtained fuel correction coefficient.
Here, to calculate the fuel correction coefficient, the ratio of the fuel input amount B and the fuel input amount A before pressure correction obtained by multiplying the fuel correction coefficient before update is obtained by the dividing unit 13 and used. In the above-described program calculation unit 17, the coefficient average value Kiε is sequentially multiplied by the existing coefficient Kiεx in the memory and updated and stored. And the fuel correction coefficient calculated | required from this is multiplied by the input required vapor | steam amount A before pressure correction in the multiplication part 22. FIG.
In calculating the fuel correction coefficient, instead of the fuel input amount A after the correction by the fuel correction coefficient before the update, the input required steam amount A before the correction by the fuel correction coefficient before the update indicated by the one-dot chain line in FIG. It is also possible to use ′. In this case, the program calculation unit 17 obtains a moving average using the obtained coefficient average value Kiε and a plurality of existing coefficients Kiεx in the memory. Then, the obtained fuel correction coefficient is multiplied by the input required steam amount A before pressure correction by the multiplication unit 22.
Also in FIG. 8, the inverse function of the fuel function F1 described in the third modification can be used.

As shown in FIG. 9, the boiler fuel input amount determination method according to the second embodiment of the present invention uses the fuel function F1 to calculate the fuel input amount by using the input required steam amount A (input required load amount A) to the boiler. This is a method of correcting the amount of fuel input to the boiler with this feedback correction amount after conversion to. Accordingly, the position of the fuel function F1 shown in FIG. 7 is arranged at the position before pressure correction, and the fuel correction coefficient is calculated using the ratio or difference between the fuel input amount B after pressure correction and the fuel input amount A before correction. Except for obtaining, the amount of fuel input to the boiler can be corrected by a method substantially similar to that of the third modification. The obtained fuel correction coefficient is multiplied by the fuel injection amount B after pressure correction by the multiplication unit 19 or added by an addition unit used instead of the multiplication unit 19.
Note that the alternate long and short dash line in FIG. 9 is substantially the same as the alternate long and short dash line in the third modification.

(Fifth modification)
The boiler fuel input amount determining method shown in FIG. 10 is obtained by converting the required steam input amount A (input required load amount A) into the fuel input amount by the fuel function F1 and then using this feedback correction amount to the fuel to the boiler. This is a method of correcting the input amount. The fuel correction coefficient is calculated by the multiplication unit 22 (or addition unit) using the ratio or difference between the fuel input amount B after pressure correction and the fuel input amount A before correction shown in FIG. The input required steam amount A (input required load amount A) before pressure correction is corrected by the fuel correction coefficient.
Further, instead of the fuel input amount A before correction, the input required steam amount A can be used. In this case, the positions of the multiplication and the fuel function F1 shown in FIG. 10 are interchanged, and the calculated fuel correction coefficient is multiplied (or added) to the fuel input amount A by the multiplication unit 22 (or addition unit). At this time, it is also possible to use the input required steam amount A instead of using the fuel input amount A when calculating the fuel correction coefficient.

When calculating the fuel correction coefficient as described above, when using multiplication, it is preferable to distinguish and use the fuel correction coefficient for each required steam amount. In addition, when using addition, it is necessary to distinguish the fuel correction coefficient for each required steam amount.

Next, examples carried out for confirming the effects of the present invention will be described. Here, FIGS. 11 (A) and 11 (B) are graphs showing changes in the generator output before and after the boiler fuel input amount determination method according to the present invention is applied, and FIGS. 12 (A) and 12 (B) are respectively shown. FIGS. 13A and 13B are graphs showing the transition of the generator output before and after the application of the boiler fuel input determining method according to the present invention, respectively, and FIGS. 13A and 13B are the before and after the application of the boiler fuel input determining method according to the present invention, respectively. FIGS. 14A and 14B are graphs showing changes in the main steam pressure, and graphs showing changes in the coal supply flow rate before and after application of the boiler fuel input amount determination method according to the present invention.

First, the fluctuation transition of the generator output before and after the application of the present invention will be described. In addition, the fluctuation range (%) shown to FIG. 11 (A), (B) has shown the generator output at the time of the actual operation with respect to the preset generator output.
Prior to application of the present invention, as shown in FIG. 11 (A), the maximum fluctuation range of the generator output was about 6%, and the fluctuation range shifted from 0%. On the other hand, after the application of the present invention, as shown in FIG. 11 (B), the maximum fluctuation range of the generator output was about 4%, and the fluctuation range was around 0%.

The transition of the generator output before and after the application of the present invention will be described. In addition, the output (%) shown to FIG. 12 (A) and (B) has shown the generator output at the time of the actual operation with respect to the maximum output of a generator.
Before the application of the present invention, as shown in FIG. 12 (A), the fluctuation was remarkable when the output of the generator was low. On the other hand, after the application of the present invention, as shown in FIG. 12 (B), the output fluctuation shown in FIG. 12 (A) could be reduced when the output of the generator was low.
From the above, it was confirmed that the generator output can be stabilized.

Next, the transition of the main steam pressure before and after the application of the present invention will be described. In addition, the main steam pressure (%) shown to FIG. 13 (A), (B) has shown the main steam pressure at the time of the actual operation with respect to the maximum main steam pressure of a boiler.
Before the application of the present invention, as shown in FIG. 13A, the fluctuation was remarkable at the place where the main steam pressure was low. On the other hand, after application of the present invention, as shown in FIG. 13 (B), the pressure fluctuation shown in FIG. 13 (A) could be reduced when the output of the generator was low.
From the above, it was confirmed that the main steam pressure can be stabilized.

Furthermore, the transition of the coal supply flow rate before and after the application of the present invention will be described. In addition, the coal supply flow rate (%) shown to FIG. 14 (A), (B) has shown the coal supply flow rate at the time of the actual operation with respect to the maximum coal supply flow rate to a boiler.
Prior to the application of the present invention, as shown in FIG. 14A, the fluctuation was remarkable at a low coal supply flow rate. On the other hand, after application of the present invention, as shown in FIG. 14 (B), the flow rate fluctuation shown in FIG. 14 (A) could be reduced where the coal supply flow rate was low.
As described above, since the coal supply flow rate can be stabilized, it was confirmed that the exhaust gas amount can be reduced by 1.7% and the coal can be reduced by 2% by mass.

As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and the matters described in the scope of claims. Other embodiments and modifications conceivable within the scope are also included. For example, a case where the boiler fuel input amount determination method of the present invention is configured by combining some or all of the above-described embodiments and modifications is also included in the scope of the present invention.
In the embodiment, the case where coal, which is a single fuel, is used as the fuel has been described. For example, a composite fuel using any one or more of solid fuel, gaseous fuel, and liquid fuel is used. It is also possible.
Further, in the above embodiment, the case where the fuel input amount obtained by the fuel function F1 is corrected by the fuel correction coefficient has been described, but it is of course possible to correct the fuel function F1 by the fuel correction coefficient.

In the embodiment described above, the required load amount of the boiler has been described as the required steam amount. However, since the steam amount of the boiler shows substantially the same transition as the generated power amount, the required load amount may be set as the required generated power amount. Is possible.
Furthermore, in the embodiment, for example, the allowable range of the coefficient average value (Kiε) in Step 2, the allowable range of x1 to x3 (r1 to r3) in Step 3 to Step 3 ″, and Step 4 to Step 4 ″. In the above description, the continuation time is set to specific numerical values, but the present invention is not limited to this. For example, if the facility can be operated stably and more economically according to the scale of the facility to which the method for determining the amount of boiler fuel input according to the present invention and the operation conditions are applied, it is of course possible to make various changes in the operation range. Is possible.

It is explanatory drawing of the determination method of the boiler fuel injection amount which concerns on the 1st Embodiment of this invention. It is explanatory drawing of the arithmetic unit which uses the determination method of the boiler fuel injection amount. It is explanatory drawing of the calculation flow of the same arithmetic unit. It is a flowchart of the program calculation part of the same calculation flow. It is explanatory drawing of the determination method of the boiler fuel injection quantity which concerns on a 1st modification. It is explanatory drawing of the determination method of the boiler fuel injection quantity which concerns on a 2nd modification. It is explanatory drawing of the determination method of the boiler fuel injection quantity which concerns on a 3rd modification. It is explanatory drawing of the determination method of the boiler fuel injection quantity which concerns on a 4th modification. It is explanatory drawing of the determination method of the boiler fuel injection quantity which concerns on the 2nd Embodiment of this invention. It is explanatory drawing of the determination method of the boiler fuel injection quantity which concerns on a 5th modification. (A), (B) is a graph which shows the change transition of the generator output before and after the application of the determination method of the boiler fuel input amount which concerns on this invention, respectively. (A), (B) is a graph which respectively shows transition of the generator output before and behind the application of the determination method of the boiler fuel input amount which concerns on this invention. (A), (B) is a graph which shows transition of the main steam pressure before and after application of the determination method of the boiler fuel input amount which concerns on this invention, respectively. (A), (B) is a graph which shows transition of the coal supply flow volume before and after application of the determination method of the boiler fuel input amount which concerns on this invention, respectively.

Explanation of symbols

10: Boiler equipment, 11: PID control section, 12: Addition section, 13: Division section, 14: Program calculation means, 15: First-order lag correction section, 16: Moving average calculation section, 17 Program calculation section, 18: Rate of change Limiting unit, 19: multiplication unit, 20: fuel input amount calculation unit, 21 and 22: multiplication unit

Claims (9)

The fuel input amount to be supplied to the boiler is determined from the input required load amount, fuel is supplied to the boiler corresponding to the determined fuel input amount, and the steam pressure generated in the boiler is measured, and the measured steam In a method of obtaining a feedback correction amount from the pressure and the set steam pressure, and correcting the fuel injection amount to the boiler with this feedback correction amount,
A plurality of ratios or differences between values after feedback correction and before correction are sequentially stored, a fuel correction coefficient is obtained from the stored plurality of values, and the value after feedback correction is corrected with the fuel correction coefficient. A method for determining the boiler fuel input amount. The fuel input amount to be supplied to the boiler is determined from the input required load amount, fuel is supplied to the boiler corresponding to the determined fuel input amount, and the steam pressure generated in the boiler is measured, and the measured steam In a method of obtaining a feedback correction amount from the pressure and the set steam pressure, and correcting the fuel injection amount to the boiler with this feedback correction amount,
A plurality of ratios or differences between the required load amount B of the boiler after feedback correction and the input required load amount A of the boiler before feedback correction are sequentially updated, and a fuel correction coefficient is calculated from the stored values. And a fuel injection amount for the boiler determined from the required load amount B after the feedback correction is corrected by the fuel correction coefficient. The fuel input amount to be supplied to the boiler is determined from the input required load amount, fuel is supplied to the boiler corresponding to the determined fuel input amount, and the steam pressure generated in the boiler is measured, and the measured steam In a method of obtaining a feedback correction amount from the pressure and the set steam pressure, and correcting the fuel injection amount to the boiler with this feedback correction amount,
A plurality of ratios or differences between the required load amount B of the boiler after feedback correction and the input required load amount A of the boiler before feedback correction are sequentially updated, and a fuel correction coefficient is calculated from the stored values. And the input required load amount A or the required load amount B is corrected by this fuel correction coefficient. The fuel input amount to be supplied to the boiler is determined from the input required load amount, fuel is supplied to the boiler corresponding to the determined fuel input amount, and the steam pressure generated in the boiler is measured, and the measured steam In a method of obtaining a feedback correction amount from the pressure and the set steam pressure, and correcting the fuel injection amount to the boiler with this feedback correction amount,
While sequentially updating the ratio or difference between the fuel input amount B obtained from the required load amount B of the boiler after feedback correction and the fuel input amount A obtained from the input required load amount A of the boiler before feedback correction. A method for determining a boiler fuel injection amount, comprising storing a plurality of fuel, obtaining a fuel correction coefficient from the plurality of stored values, and correcting the fuel injection amount B with the fuel correction coefficient. 5. The boiler fuel input amount determination method according to claim 4, wherein when the fuel correction coefficient is determined based on a ratio or difference between the values of the fuel input amount B and the fuel input amount A, the calculated fuel correction coefficient is used as the fuel correction coefficient. A method for determining a boiler fuel input amount, wherein the input required load amount A is corrected. The fuel input amount to be supplied to the boiler is determined from the input required load amount, fuel is supplied to the boiler corresponding to the determined fuel input amount, and the steam pressure generated in the boiler is measured, and the measured steam In a method for obtaining a feedback correction amount from a pressure and a set steam pressure, converting the input required load amount to the boiler into the fuel input amount, and then correcting the fuel input amount to the boiler with the feedback correction amount,
A plurality of ratios or differences between the fuel injection amount after feedback correction and the fuel input amount before correction are sequentially stored, a fuel correction coefficient is obtained from the stored multiple values, and the fuel input amount after the feedback correction is calculated based on the fuel correction coefficient. A method for determining a boiler fuel input amount, wherein one of the fuel input amount before the feedback correction and the input required load amount is corrected. The boiler fuel input amount determination method according to any one of claims 1 to 6, wherein when the ratio between the values after feedback correction and before correction is used as the fuel correction coefficient, The ratio of the value to be updated is sequentially multiplied and stored, and when the difference between the values after the feedback correction and before the correction is used, the difference between the values to be updated is sequentially added and stored in the difference between the values obtained in advance. And determining the fuel correction coefficient from the stored value. The boiler fuel input amount determination method according to any one of claims 1 to 6, wherein the fuel correction coefficient stores a ratio or difference between values after the feedback correction and before the correction as a moving average, and stored. A boiler fuel input amount determining method, characterized in that the boiler fuel input amount is obtained from the stored value. The boiler fuel input amount determination method according to any one of claims 7 and 8, wherein the update timing of the value after the feedback correction and before the correction is determined based on a reaction time of the fuel supplied to the boiler. A method for determining the amount of boiler fuel input.

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