JP2011099608A - Boiler combustion control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem in air-fuel ratio constant value control of a boiler wherein constant value control of CO becomes unstable in control restrictions and CO concentration control, when there are specific characteristics in CO discharge characteristics with respect to change of O<SB>2</SB>. <P>SOLUTION: The boiler combustion control device includes an air flow rate control device 22 and a fuel flow rate control device 21 controlling a fuel flow rate and an air flow rate supplied to the boiler 1, and an air amount is controlled based on an air-fuel ratio set value. The boiler combustion control device includes an O<SB>2</SB>control device 26 generating a first adjustment signal based on the an O<SB>2</SB>concentration in exhaust gas of the boiler, and a CO change rate control device 27 generating a second adjustment signal based on a change rate of a CO concentration in the exhaust gas of the boiler. An adjustment signal with higher priority of the first adjustment signal and the second adjustment signal is selected in a high selector 28, and by providing it to the air-fuel ratio set value as a bias (deflection) signal, an energy-saving and low pollution combustion system is constructed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a boiler combustion control device that controls the flow rate of fuel and air supplied to a boiler such as a thermal power plant, and particularly controls the amount of air appropriately during load fluctuations to suppress CO emissions in exhaust gas. The present invention relates to a boiler combustion control apparatus.

In conventional boiler combustion control, adjustment of the fuel amount and the air amount with respect to the boiler load is performed in advance, and the excess air ratio control according to the air-fuel ratio (fuel / air ratio) setting characteristics is performed. . When O ₂ (oxygen) control and CO (carbon monoxide) control are added to this excess air ratio control (air-fuel ratio control), the deviation between the measured value of O ₂ concentration in the exhaust gas and the target value of O ₂ concentration Is used to correct the air-fuel ratio set value by calculation as a conversion coefficient. Further, the CO concentration of exhaust gas is measured, and the exhaust gas O ₂ concentration target value is multiplied by the conversion coefficient of the difference from the CO concentration target value. Then, after obtaining the final target value of the exhaust gas O ₂ concentration, the boiler air amount is adjusted by air-fuel ratio control corrected by the deviation from the actually measured O ₂ concentration. (See Patent Document 1 and Patent Document 2)

JP-A-6-117627 (FIGS. 3 and 4) JP-A-6-180116 (FIGS. 3 and 4)

In the conventional boiler combustion control device, an air-fuel ratio setting system that adjusts the air amount according to the fuel amount is applied by an air-fuel ratio setting device, and O ₂ control and CO control are further added. In this case, the air-fuel ratio is set by changing the air-fuel ratio setting by adding the controller output of the CO control and the controller output of the O ₂ control with the cascade signal. In this case, it is necessary to carry out the O ₂ concentration control together, and when there is a characteristic specific to the CO emission characteristic with respect to the change of O ₂ , the constant value control of CO becomes unstable. There were problems in control and CO concentration control.

The present invention has been made to solve the above-described problems, and can perform CO emission suppression control even when O ₂ concentration control is not performed in advance, and is also suitable for the CO concentration control method. It is an object of the present invention to provide a boiler combustion control device capable of making the amount of combustion air appropriate by proper CO control.

A boiler combustion control device according to the present invention is a boiler combustion control device that controls a fuel flow rate and an air flow rate that are supplied to a boiler, based on a signal from an air flow rate detection device that detects an air flow rate supplied to the boiler. An air flow rate control device that controls the flow rate of air supplied, a fuel flow rate control device that controls the flow rate of fuel supplied to the boiler based on a signal from a fuel flow rate detection device that detects the flow rate of fuel supplied to the boiler, and a fuel flow rate detection device An air-fuel ratio setting device that calculates an air-fuel ratio set value that is set according to the fuel flow rate detected from the measured value of the fuel flow rate, and an O ₂ (oxygen) concentration and an O ₂ concentration target value in the exhaust gas of the boiler The O ₂ control device that creates the first adjustment signal based on the deviation from the above, the change rate of the CO (carbon monoxide) concentration in the exhaust gas of the boiler, and the upper limit target value of the CO concentration change rate A CO change rate control device that creates a second adjustment signal based on the deviation between the first adjustment signal and the second adjustment signal, a high selector that selects an adjustment signal with a higher priority among the first adjustment signal and the second adjustment signal, A first calculation means that creates a control signal by applying the selected adjustment signal as a bias (bias) signal to the air-fuel ratio setting value calculated by the air-fuel ratio setting device, and uses the control signal as a control value for the air flow rate control device; A boiler master that detects the steam pressure of the boiler and creates a control signal based on the deviation between the detected pressure and the boiler pressure target value, and uses the control signal created by the boiler master as the control value of the fuel flow control device. 2 arithmetic means.

Further, the boiler combustion control apparatus according to the present invention detects a fuel flow rate supplied to the boiler, detects a fuel adjustment control system that adjusts the fuel flow rate based on the detected fuel flow rate, and detects an air flow rate supplied to the boiler. In the boiler combustion control device having an air amount adjustment control system for adjusting the air flow rate based on the detected air flow rate, the boiler steam pressure is detected, and the boiler combustion control signal is detected by the detected pressure signal. A first control device that provides a boiler combustion control signal generated by the boiler master to the fuel adjustment control system and the air amount adjustment control system, and based on the detected fuel flow rate, according to the fuel flow rate A second control device for providing the air amount adjustment control system with a control signal of the air-fuel ratio setting value calculated by the air-fuel ratio setting device. When having a O ₂ controller for generating a first adjustment signal based on the deviation between the O _{2 (oxygen)} concentration and the O ₂ concentration target value of the exhaust gas of the boiler, the first from the O ₂ control system A third control device that applies a bias to the air-fuel ratio setting value calculated by the air-fuel ratio setting device in accordance with the adjustment signal; and a change rate of CO (carbon monoxide) concentration and a change rate of CO concentration in the exhaust gas of the boiler An air-fuel ratio setting value calculated by the air-fuel ratio setting device by the second adjustment signal from the CO change rate control device, having a CO change rate control device that creates a second adjustment signal based on the deviation from the upper limit target value And a fourth control device that applies a bias to the first control signal, and a high-priority adjustment among the first adjustment signal from the third control device and the second adjustment signal from the fourth control device. Select the signal using the high selector, and select the signal selected with the high selector. A bias (bias) is applied to the air-fuel ratio set value calculated by the air-fuel ratio setting device using the trim signal.

When performing CO (carbon monoxide) concentration control, the boiler combustion control apparatus according to the present invention can achieve air-fuel ratio control in combination with O ₂ concentration control or independently, and more combustion air than necessary. This makes it possible to control the air-fuel ratio at the limit where the supply of the amount is suppressed and the combustion state in which the boiler is incompletely burned and CO is not generated, so the power of the combustion air fan and the heat of the exhaust gas can be accurately controlled. Loss can be reduced, and CO emission suppression by good boiler combustion can be achieved.
Even if the CO concentration increases abnormally, the amount of combustion air can be appropriately adjusted by detecting the rate of change in the concentration and applying a bias to the air-fuel ratio control signal to incorporate CO emission suppression control in the exhaust gas. Therefore, an advantageous boiler combustion method can be taken from the viewpoint of energy saving and pollution prevention.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram which shows Embodiment 1 of this invention. It is a whole block diagram which shows Embodiment 2 of this invention. It is a whole block diagram which shows Embodiment 3 of this invention. It is a whole block diagram which shows Embodiment 4 of this invention. It is a figure which shows the characteristic of the air fuel ratio according to a fuel flow volume. Is a diagram showing an O ₂ density characteristics of the exhaust gas in accordance with the boiler load. Is a diagram showing the CO concentration profile in the exhaust gas with respect to O ₂ concentration change.

Embodiment 1 FIG.
Hereinafter, the boiler combustion control apparatus in Embodiment 1 of this invention is demonstrated based on FIG. In FIG. 1, a burner is installed on a predetermined wall portion of a boiler 1, and fuel and air are supplied to the burner from a fuel supply path 2 and an air supply path 3, respectively, where the fuel and air are mixed and burned. Thus, the object to be heated in the boiler 1, for example, water is heated to output steam from the pipe 4 and sent to the next process (not shown). Further, the exhaust gas burned in the boiler 1 is discharged from the chimney 7 through the exhaust pipe 5 and the dust collector 6.

The fuel supply path 2 is provided with a fuel flow rate adjusting means 8 such as an adjustment valve for adjusting the amount of fuel supplied to the boiler 1 and a fuel flow rate detecting device 9 for detecting the fuel flow rate supplied to the boiler 1, and also an air supply path. 3, a variable speed blower for adjusting the amount of air supplied to the boiler 1, an air flow rate adjusting means 10 such as VVVF, and an air flow rate detection device 11 for detecting the air flow rate supplied to the boiler 1 are provided. Further, the pipe 4 is provided with a steam pressure detecting device 12 for detecting the steam pressure and a boiler load detecting device 13 for detecting the load of the boiler 1, and the exhaust pipe 5 detects the concentration of CO (carbon monoxide). A CO concentration detection device 14 and an O ₂ concentration detection device 15 for detecting the concentration of O ₂ (oxygen) are provided.

The boiler control device 20 is detected by a fuel adjustment control system including a fuel flow rate control device 21 that adjusts the fuel flow rate by the fuel flow rate adjustment means 8 based on the fuel flow rate detected by the fuel flow rate detection device 9, and an air flow rate detection device 11. And an air amount adjustment control system comprising an air flow rate control device 22 that adjusts the air flow rate by the air flow rate adjusting means 10 based on the air flow rate.
The boiler control device 20 has a boiler master 23 that creates a boiler combustion control signal based on the deviation between the steam pressure of the boiler 1 detected by the steam pressure detection device 12 and the boiler pressure target value. A first control device is provided for supplying a combustion control signal to the fuel adjustment control system and the air amount adjustment control system. In other words, the boiler combustion control signal created by the boiler master 23 is given to the flow rate control values of the fuel flow rate control device 21 and the air flow rate control device 22 as the control value of the bias signal via the multipliers 24a and 24b as calculation means. .

  Further, the boiler control device 20 has an air-fuel ratio setting device 25 that calculates an air-fuel ratio set value shown in FIG. 5 that is set according to the fuel flow rate based on the fuel flow rate detected by the fuel flow rate detection device 9. The air-fuel ratio setting device 25 calculates a control signal for the air-fuel ratio set value to the air amount adjustment control system.

Further, the boiler control device 20 is also provided with a control device for performing O ₂ (oxygen) control and CO (carbon monoxide) control of exhaust gas discharged from the boiler 1.
That is, the O ₂ (oxygen) concentration measurement value in the exhaust gas detected by the O ₂ concentration detection device 15 and the O ₂ concentration target value set according to the boiler load detected by the boiler load detection device 13. It has an O ₂ control device 26 that creates a first adjustment signal based on the deviation, and is biased to the air-fuel ratio setting value calculated by the air-fuel ratio setting device 25 by the first adjustment signal from the O ₂ control device 26 ( And a third control device for correcting the air-fuel ratio set value.

Further, the CO that creates the second adjustment signal based on the deviation between the CO (carbon monoxide) concentration change rate in the exhaust gas detected by the CO concentration detection device 14 and the upper limit target value of the CO concentration change rate. A change rate control device 27 is provided, and a bias (bias) is given to the air-fuel ratio setting value calculated by the air-fuel ratio setting device 25 by the second adjustment signal from the CO change rate control device 27, so that the air-fuel ratio set value is A fourth control device for correction is provided.
The method for detecting the change rate of the CO concentration is the amount of change within the measurement time of the difference between the previous value COold and the current value COnew of the CO concentration measured during a short measurement scan time ΔT (usually around 1 second). The detection is performed when the change rate exceeds the allowable limit value ΔCO (usually 100 ppm). The relational expression is as follows.
(COnew-COold) / ΔT> ΔCO

The high selector 28 compares the control value of the first adjustment signal output from the O ₂ control device 26 with the control value of the second adjustment signal output from the CO change rate control device 27 to obtain the first adjustment signal. Among the second adjustment signals, an adjustment signal having a higher priority (for example, one having a larger control value) is selected. The adjustment signal selected by the high selector 28 is given to the multiplier 24c of the computing means as a control value for biasing (biasing) the air-fuel ratio setting value from the air-fuel ratio setting device 25. The multiplier 24 c biases (bias) the adjustment signal selected by the high selector 28 to the air-fuel ratio set value, and uses the biased control signal as the target control value of the air flow rate control device 22.
As a specific configuration of the high selector 28, a converter that inputs two voltage signals from various converters, selects a higher one of the two input signals, and outputs a current signal or a voltage signal is used. .

High selector 28, CO rate of change controller 27 detects the rate of change of CO concentration during load change, when it becomes more than the allowable limit value ΔCO rate of change is set in advance, first of O ₂ controller 26 The output value of the second adjustment signal from the CO change rate control device 27 is preferentially output from the output value of the adjustment signal 1 until the change rate of CO becomes substantially zero. Here, the change rate of CO is substantially zero, which is 30 ppm or less, more preferably 10 ppm or less.

Next, the operation of the first embodiment of the present invention will be described.
In the burner combustion of the boiler 1, fuel and air are mixed and burned. The fuel / air ratio (air / fuel ratio) is set to the air / fuel ratio shown in FIG. The amount of air to be supplied is set in advance according to the fuel burned using this air-fuel ratio.
That is, the air-fuel ratio setting device 25 calculates the air-fuel ratio setting value based on the fuel flow rate detected by the fuel flow rate detection device 9, and the air flow control device 22 uses the air-fuel ratio setting value as a target value to optimize the air flow rate. The air flow rate adjusting device 10 is controlled based on the air flow rate detected by the air flow rate detecting device 11. In this case, the air-fuel ratio set value is biased by the multiplying means 24 b by the boiler combustion control signal created by the boiler master 23 and is corrected according to the steam pressure of the boiler 1.

  On the other hand, the boiler combustion control signal created by the boiler master 23 is biased by the multiplying means 24a to create the control value of the fuel flow rate control device 21, and the fuel flow rate control device 21 uses the above control value so that the fuel flow rate is optimized. Based on the fuel flow rate detected by the fuel flow rate detection device 9, the fuel flow rate adjustment device 8 is controlled to adjust the fuel flow rate.

  In general, in the combustion of boilers, the air-fuel ratio may be small when the fuel flow rate is close to the rated value, that is, when the fuel flow rate is large. It is necessary to supply a large amount, and smoke is generated unless the air-fuel ratio in the low load range is set large as shown in FIG. That is, the air-fuel ratio is not constant with respect to the fuel flow rate, and has a non-linear characteristic that increases as the fuel flow rate decreases.

However, if the supply of the air amount is continued by setting the air-fuel ratio shown in FIG. 5, the combustion air supply becomes excessively excessive due to changes in the combustion characteristics of the boiler, resulting in an uneconomical operation, or insufficient air supply. Incomplete combustion may cause black smoke, which may cause problems in terms of pollution.
Therefore, in order to confirm that excess air is properly supplied, the O ₂ (oxygen) concentration in the exhaust gas is detected by the O ₂ concentration detection device 15 and the boiler load detection device 13 detects the boiler load, The multiplier shown in FIG. 1 is added to the air-fuel ratio set value set by the air-fuel ratio setting device 25 so that the O ₂ control device 26 has the characteristics of the boiler load (steam amount) and the exhaust gas O ₂ concentration shown in FIG. 24c is used to give a bias for O ₂ correction, and the amount of supplied air is corrected as O ₂ control of exhaust gas.

With only the exhaust gas O ₂ concentration control used in this method, the combustion state may not be found accurately when external air is mixed into the exhaust gas for measuring the O ₂ concentration. Therefore, the CO concentration of the combustible component remaining in the exhaust gas is detected, and the set value for adjusting the exhaust gas O ₂ concentration is corrected according to the detected CO concentration value so that the CO concentration in the exhaust gas becomes the CO concentration target value. Conventionally, a CO control device to be controlled has been provided.

In this case, O ₂ and CO emissions characteristics of CO concentration values for density variation as an example of 100% load and 25% load are shown in Figure 7, the O ₂ concentration is reduced excess air ratio is lowered In some cases, incomplete combustion occurs and the CO concentration value increases rapidly, and when the O ₂ concentration increases, the CO concentration value decreases slowly.
When the constant concentration control of CO is required for a boiler having the characteristics of CO shown in FIG. 7, the control becomes unstable, and high-concentration CO is discharged or excessive combustion air is supplied. Therefore, it is not preferable from the viewpoint of environmental conservation, and it is uneconomical from the viewpoint of energy saving.

Therefore, in the present invention, the CO change rate control device 27 is provided instead of the CO control device, and the control value of the first adjustment signal from the O ₂ control device 26 and the CO change rate control device are further used by using the high selector 28. The control value of the second adjustment signal from 27 is compared, and an adjustment signal having a high priority is selected. The adjustment signal selected by the high selector 28 is applied as a bias value to the air-fuel ratio setting value from the air-fuel ratio setting device 25 by the multiplier 24c to correct the air-fuel ratio setting value.

That is, the high selector 28 selects the first adjustment signal from the O ₂ control device 26 during normal operation so that the characteristics of the boiler load (steam amount) and the exhaust gas O ₂ concentration shown in FIG. 6 are obtained. In addition, an O ₂ correction bias is applied to the air / fuel ratio set value from the air / fuel ratio setting device 25 by using the multiplier 24c, and the supply air amount is corrected as O ₂ control of the exhaust gas.
However, when the CO change rate control device 27 detects the change rate of the CO concentration at the time of load change and becomes equal to or greater than a preset change rate allowable limit value ΔCO, the high selector 28 controls the O ₂ control device 26. The first adjustment signal is switched in preference to the second adjustment signal from the CO change rate suppression control device 27, and the state is continued until the CO change rate becomes substantially zero and CO is not detected.

As described above, according to the first embodiment, when the CO suddenly increases at the time of a load change or the like, the high selector 28 is used to preferentially select the O ₂ control signal to the CO change rate suppression control signal. Thus, the adjustment signal is switched, and the adjustment signal is biased to the air-fuel ratio control signal, whereby incomplete combustion can be prevented and a boiler combustion method that is advantageous in terms of pollution prevention can be taken. By using this high selector method, it is possible to suppress the emission of high concentration CO even when the O ₂ concentration control is not performed in advance.

Embodiment 2. FIG.
Next, the boiler combustion control apparatus in Embodiment 2 of this invention is demonstrated based on FIG. 2, in addition to the boiler combustion control device in the first embodiment shown in FIG. 1, a CO non-detection control device 29 is provided in the boiler control device 20, and the output of the CO non-detection control device 29 is supplied to the high selector 28. This is input as a control value of the adjustment signal. Other configurations are the same as those in FIG. 1 and are denoted by the same reference numerals, and description thereof is omitted.

The CO non-detection control device 29 creates a third adjustment signal based on the deviation between the CO concentration value in the exhaust gas detected by the CO concentration detection device 14 and the upper limit management value of the CO concentration value. That is, the CO non-detection control device 29 sets the upper limit management value of the CO concentration value to, for example, 30 ppm, more preferably 10 ppm or less, and outputs an adjustment signal until the CO concentration is substantially undetected.
The high selector 28 controls the control value that is the first adjustment signal from the O ₂ control device 26, the control value that is the second adjustment signal from the CO change rate control device 27, and the control value from the CO non-detection control device 29. The three adjustment signals are compared with the control value, which is the third adjustment signal, and an adjustment signal having a high priority (a large absolute value) is extracted. The multiplier 24c is the magnitude of the adjustment signal extracted by the high selector 28. Accordingly, the air-fuel ratio setting value from the air-fuel ratio setting device 25 is biased (biased) to correct the air-fuel ratio setting value.

In the first embodiment, an adjustment signal is generated by selecting the first adjustment signal of the deviation from the O ₂ control device 26 and the _second adjustment signal from the CO change rate control device 27 by the high selector 28. However, since the second adjustment signal is generated with the rate of change of CO, there is a case where CO emission is set in a high concentration emission state. Therefore, in the invention of the second embodiment, the high selector 28 compares the absolute values of the three adjustment signals based on the deviations, and takes out the adjustment signal having a high priority. The control target value of the O ₂ control device 26 is changed so that the third adjustment signal becomes zero, and control is performed so that the deviation between the two control devices becomes zero.

In the invention of the second embodiment, when the CO concentration exceeding the control upper limit value of CO concentration is measured when the load is stable, the adjustment signal of the O ₂ control device 26 is prioritized from the adjustment signal of the CO non-detection control device 29. The adjustment signal is selected and switched, and the output from the CO non-detection control device 29 is given priority and output to the high selector 28 until the CO concentration becomes substantially undetected, so continuous discharge of low concentration CO in the normal combustion state Can also be reduced.

On the other hand, when the CO concentration below the CO concentration control upper limit value is measured, the absolute value of the third adjustment signal of the CO non-detection control device 29 is also compared, so this third adjustment signal is selected. Thus, in a normal combustion state, the amount of unnecessary combustion air can be reduced by continuously discharging CO at a low concentration, and the power of the combustion air fan and the heat loss of the exhaust gas can be reduced. By adopting this method, it is possible to suppress the emission of high-concentration CO even when the O ₂ concentration control is not performed in advance.

Embodiment 3 FIG.
Next, the boiler combustion control apparatus in Embodiment 3 of this invention is demonstrated based on FIG. 3, in addition to the boiler combustion control device in the second embodiment shown in FIG. 2, a CO emission characteristic database 30 is provided in the boiler control device 20. Other configurations are the same as those in FIG. 1 and FIG.

In the fuel combustion characteristics of the boiler 1, when the O ₂ concentration is measured by increasing the air-fuel ratio, the characteristics of the O ₂ concentration and the CO concentration in the exhaust gas are the combustion characteristics in which CO is not detected, and the amount of CO emission is small. However, it has CO emission characteristics unique to boilers that continue to generate. The CO emission characteristic of the curve C2 shown in FIG. 7 is an emission characteristic in which CO is not detected, and the CO emission characteristic of the curve C1 shown in FIG. 7 is an emission characteristic in which a small amount of CO continues to be generated even when the O ₂ concentration increases. .

  The CO emission characteristic database 30 holds the CO emission characteristics of such several types of boilers. According to the emission characteristics of the boiler 1 from this CO emission characteristic database 30, the CO concentration upper limit management value of the CO non-detection control device 29 is COmin for detecting the CO minimum value shown in FIG. 7 or COzero with zero CO detection. And is set as the management target value COsv of the CO non-detection control device 29.

The control method of the CO non-detection control device 29 is such that when the measured CO concentration value COnew exceeds the management target value COsv of the CO concentration, the high selector 28 is set so that the CO concentration becomes the management target value COsv that is not substantially detected. The control value is output to.
The control target value of the CO concentration is preferably about 30 ppm, usually less than the national emission standard value (300 ppm).

  The invention of the third embodiment is based on the CO emission characteristic database 30 having the CO emission characteristics of several types of boilers, and the CO non-detection control device 29 is used as the upper limit management value of the CO concentration according to the emission characteristics of the boiler. Since the management target value COsv is set, an appropriate management target value for CO emission is set, and continuous emission of low concentration CO in a normal combustion state can also be reduced.

Embodiment 4 FIG.
Next, the boiler combustion control apparatus in Embodiment 4 of this invention is demonstrated based on FIG. In FIG. 4, in addition to the boiler combustion control device in the third embodiment shown in FIG. 3, a CO change rate alarm device 31 is provided in the boiler control device 20. Other configurations are the same as those in FIGS. 1 to 3, and are denoted by the same reference numerals and description thereof is omitted.
The CO change rate warning device 31 calculates the CO change rate by the CO change rate control device 27, and when the deviation from the upper limit management value of the change rate of the CO concentration becomes a set value or more, a power plant or the like The warnings are transmitted to the managers using buzzers and lamps.

  In the invention of the fourth embodiment, the CO change rate is calculated by the CO change rate control device 27, and when the deviation from the upper limit control value of the CO concentration change rate becomes equal to or larger than the set value, the CO change Since the alarm warning is transmitted to the manager of the power plant by the rate alarm device 31, the manager of the power plant can quickly grasp the abnormal combustion state of the boiler in which the CO concentration is abnormally increased. Since it is possible to take a transition to a good combustion state, it is possible to prevent the boiler from continuing to operate in good condition and to prevent the occurrence of black smoke in terms of pollution at an early stage.

  Although the invention of the fourth embodiment has been described with respect to the boiler combustion control device having the CO non-detection control device 29 and the CO emission characteristic database 30 according to the third embodiment, the CO change rate alarm device 31 is provided. The invention can also be applied to the invention of the first embodiment not equipped with the detection control device 29 and the invention of the second embodiment not equipped with the CO emission characteristic database 30 equipped with the CO change rate alarm device 31.

1: Boiler 2: Fuel supply path 3: Air supply path 4: Piping 5: Exhaust pipe 6: Dust collector 7: Chimney 8: Fuel flow rate adjusting means (regulating valve)
9: Fuel flow rate detection device 10: Air flow rate adjustment means 11: Air flow rate detection device 12: Steam pressure detection device 13: Boiler load detection device 14: CO concentration detection device 15: O ₂ concentration detection device 20: Boiler control device 21: Fuel flow control device 22: Air flow control device 23: Boiler master 24a, 24b, 24c: Calculation means (multiplier)
25: Air-fuel ratio setting device 26: O ₂ control device 27: CO change rate control device 28: High selector 29: CO non-detection control device 30: CO emission characteristic database 31: CO change rate alarm device

Claims (6)

In a boiler combustion control device for controlling a fuel flow rate and an air flow rate supplied to a boiler, air for controlling an air flow rate supplied to the boiler based on a signal from an air flow rate detection device for detecting an air flow rate supplied to the boiler A flow rate control device, a fuel flow rate control device that controls a fuel flow rate supplied to the boiler based on a signal from a fuel flow rate detection device that detects a fuel flow rate supplied to the boiler, and a fuel detected by the fuel flow rate detection device An air-fuel ratio setting device that calculates an air-fuel ratio setting value that is set according to the fuel flow rate from the measured value of the flow rate, and the deviation between the O ₂ (oxygen) concentration in the exhaust gas of the boiler and the O ₂ concentration target value The O ₂ control device that creates the first adjustment signal based on the deviation of the CO (carbon monoxide) concentration change rate in the exhaust gas of the boiler and the upper limit target value of the CO concentration change rate CO change rate control device for generating a second adjustment signal based on the difference, a high selector for selecting a high-priority adjustment signal among the first adjustment signal and the second adjustment signal, and selection by this high selector The control signal is generated by applying the adjusted signal as a bias (bias) signal to the air-fuel ratio set value calculated by the air-fuel ratio setting device, and the control signal is used as a control value for the air flow rate control device. A boiler master that detects a steam pressure of the boiler and creates a control signal based on a deviation between the detected pressure and a boiler pressure target value; a control signal created by the boiler master is a control value of the fuel flow control device; The boiler combustion control apparatus provided with the 2nd calculating means.   The boiler combustion control apparatus according to claim 1, wherein the control signal generated by the boiler master is multiplied by the control signal generated by the first arithmetic means to obtain a control value of the air flow rate control apparatus. A CO non-detection control device that creates a third adjustment signal based on the deviation between the CO (carbon monoxide) concentration value in the exhaust gas of the boiler and the upper limit control value of the CO concentration value is provided, and the high selector performs O ₂ control. The first adjustment signal from the device, the second adjustment signal from the CO change rate control device, and the third adjustment signal from the CO non-detection control device are compared, and the absolute value of The boiler combustion control according to claim 1 or 2, wherein a large signal is selected, and the adjustment signal selected by the high selector is applied as a bias (bias) signal to the air-fuel ratio setting value calculated by the air-fuel ratio setting device. apparatus.   A database having CO emission characteristics of several types of boilers is provided, and the upper limit management value of the CO non-detection control device of the CO non-detection control device is selected from the database according to the suitable CO emission characteristics. 4. The boiler combustion control apparatus according to claim 3, wherein a signal of either COzero or COmin for detecting the minimum value can be selected.   An alarm that outputs an alarm when a deviation between the CO (carbon monoxide) concentration change rate in the exhaust gas and the upper limit target value of the CO concentration change rate detected by the CO change rate control device exceeds a predetermined value. The boiler combustion control apparatus according to any one of claims 1 to 4, further comprising an apparatus. A fuel adjustment control system that detects the fuel flow rate supplied to the boiler and adjusts the fuel flow rate based on the detected fuel flow rate, and detects the air flow rate supplied to the boiler, and air is detected based on the detected air flow rate. In a boiler combustion control device having an air amount adjustment control system for adjusting a flow rate,
A boiler master that detects a steam pressure of the boiler and generates a boiler combustion control signal based on the detected pressure signal; the boiler combustion control signal created by the boiler master is used as the fuel adjustment control system and the air amount adjustment control system; A first control device to give to
Based on the detected fuel flow rate, an air-fuel ratio setting device that calculates an air-fuel ratio setting value that is set according to the fuel flow rate is provided. Control of the air-fuel ratio setting value that is calculated by the air-fuel ratio setting device A second control device for providing a signal to the air amount adjustment control system;
It has an O ₂ controller for generating a first adjustment signal based on the deviation between the O _{2 (oxygen)} concentration and the O ₂ concentration target value of the exhaust gas of the boiler, first from the O ₂ control system A third control device for applying a bias (bias) to the air-fuel ratio setting value calculated by the air-fuel ratio setting device by an adjustment signal;
A CO change rate control device that creates a second adjustment signal based on a deviation between a change rate of CO (carbon monoxide) concentration in the exhaust gas of the boiler and an upper limit target value of the change rate of CO concentration; A fourth control device that applies a bias (bias) to the air-fuel ratio setting value calculated by the air-fuel ratio setting device according to a second adjustment signal from a CO change rate control device;
Among the first adjustment signal from the third control device and the second adjustment signal from the fourth control device, an adjustment signal having a high priority is selected using a high selector, and the high selector A boiler combustion control device that applies a bias (bias) to an air-fuel ratio setting value calculated by the air-fuel ratio setting device according to a selected adjustment signal.

Images