JP2010043768A - Control method of boiler and boiler system using the control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boiler control method and a boiler system suppressing start and stop of stage value control boilers even if a necessary combustion amount and a combustion amount in each combustion position of the stage value control boilers do not agree to each other when combustion amount larger than the combustion amount of the stage value control boilers is secured by the stage value control boilers. <P>SOLUTION: The boiler control method includes: the stage value control boilers 2; a proportional control boiler 3; a combustion position selection means for selecting the combustion positions of the stage value control boilers 2; and a combustion ratio control means for determining combustion amount of the proportional control boiler 3. The combustion position selection means selects the combustion position where the combustion amount of the stage value control boilers 2 is maximized in a range below the necessary combustion amount. The combustion ratio control means makes adjustment to a combustion ratio so that the combustion amount of the proportional control boiler 3 becomes a shortage combustion amount which is a difference between the necessary combustion amount and the combustion amount of the stage value control boilers 2 in the selected combustion position. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a boiler control method and a boiler system that are configured by a plurality of boilers and that control a controlled object composed of steam pressure or water temperature by adjusting a combustion amount.

Conventionally, when obtaining a steam generation amount larger than the steam generation amount that can be supplied by one boiler, for example, three-position control of high combustion amount (H), low combustion amount (L), and combustion stop is possible. Using a number of so-called stage value boilers, the pressure of the steam concentrated from each boiler to the steam header is detected by the pressure regulator, the required steam volume is calculated from the pressure, and the number of boilers to be started and each boiler A technique for controlling the combustion position is disclosed (for example, see Patent Document 1).
Japanese Patent No. 2544948

  However, when the steam generation amount of the boiler is controlled stepwise by the combustion position of the step value control boiler as described above, the steam generation amount of the step value control boiler at the selected combustion position and the necessary steam corresponding to the load fluctuation If the quantity matches, the stage value control boiler will operate steadily, but if the required steam volume does not match the steam generation amount of the stage value control boiler, the stage value control boiler will start and stop repeatedly. Thus, the average steam generation amount within a predetermined time is made to coincide with the required steam amount. Therefore, there is a problem that purge loss occurs every time the step value control boiler is started, and that heat transfer efficiency is lowered and equipment is deteriorated due to a large amount of soot at the time of starting.

  The present invention has been made in consideration of such circumstances. When a combustion amount larger than the combustion amount of the step value control boiler is secured by the step value control boiler, the required combustion amount and the step value control boiler are provided. An object of the present invention is to provide a boiler control method and a boiler system capable of suppressing the start and stop of a step value control boiler even when the combustion amounts at the respective combustion positions do not match.

In order to solve the above problems, the present invention proposes the following means.
The invention according to claim 1 includes a step value control boiler in which the combustion amount can be increased or decreased stepwise according to the selected combustion position, and a proportional control boiler in which the combustion amount can be increased or decreased continuously. A boiler control method for adjusting a control target consisting of steam pressure or water temperature according to a combustion amount, wherein a combustion position of the step value control boiler is determined according to a change in the combustion amount of the step value control boiler. The required combustion amount is selected to be the maximum within the range of the required combustion amount or less, and the shortage combustion amount which is the difference between the required combustion amount and the combustion amount of the stage value control boiler at the selected combustion position, It is supplemented by combustion of a proportional control boiler.

  The invention according to claim 2 is a boiler system that includes a plurality of boilers, and controls a control target composed of steam pressure or water temperature by adjusting a combustion amount of the plurality of boilers, according to a selected combustion position. A step value control boiler in which the combustion amount can be increased or decreased in stages, a proportional control boiler in which the combustion amount can be increased or decreased continuously, and a combustion position selection means for selecting the combustion position of the step value control boiler; Combustion ratio control means for determining the combustion amount of the proportional control boiler, the combustion position selection means, the combustion amount of the stage value control boiler is required combustion that is required according to the fluctuation of the control target The combustion position at which the maximum value is selected in a range less than or equal to the amount is selected, and the combustion ratio control means is configured such that the combustion amount of the proportional control boiler is the step value control boiler at the combustion position selected as the required combustion amount. And adjusting the combustion ratio so that the lack of combustion quantity is the difference between the combustion amount.

  According to the boiler control method and the boiler system according to the present invention, the combustion value of the step-value control boiler is selected to the combustion position where the combustion value becomes the maximum value within the range of the required combustion amount or less, and the shortage combustion amount is combusted in the proportional control boiler. Therefore, starting and stopping of the step value control boiler are suppressed.

  In this specification, a stage value control boiler is a method that controls the amount of combustion by selectively turning combustion on and off, or by adjusting the size of the flame, etc., according to the selected combustion position. A boiler that can increase or decrease the combustion amount in stages, and has a combustion position of 10 or less that can ensure a significant advantage in terms of equipment structure and cost over a proportional control boiler.

  In addition, a proportional control boiler is a boiler that continuously increases or decreases the amount of combustion, and continuous control means that even when calculations and signals in the control unit are digitally handled in stages. For example, a control amount by a control mechanism such as a valve is set to be smaller than variations of combustion air, fuel gas, and the like, and includes those that are controlled virtually continuously.

  The invention according to claim 3 is the boiler system according to claim 2, wherein the combustion amount in the maximum combustion of the proportional control boiler is an increase / decrease amount of the combustion position selected stepwise of the step value control boiler. It is characterized by being over the maximum amount.

According to the boiler system according to the present invention, the combustion amount (combustion capacity) in the maximum combustion of the proportional control boiler is equal to or greater than the maximum amount of the increase / decrease amount of the combustion position selected stepwise of the step value control boiler. The shortage combustion amount can always be adjusted by the proportional control boiler.
Even if the load fluctuation is large and the required combustion amount fluctuates across the combustion position, if the fluctuation amount is within the range of the combustion capacity of the proportional control boiler, start the step value control boiler, Since the combustion amount of the proportional control boiler is adjusted by control without stopping, the start and stop of the step value control boiler can be suppressed even when there is a load fluctuation across the combustion position.

  According to the boiler control method and the boiler system according to the present invention, even if the combustion amount at the combustion position of the step value control boiler and the required combustion amount do not match, the start and stop of the step value control boiler are suppressed. As a result, purge loss can be reduced, and reduction in heat transfer efficiency and equipment deterioration due to soot generation at the time of startup can be suppressed.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram showing an embodiment of a boiler system according to the present invention, and reference numeral 1 denotes a boiler system. In this embodiment, the boiler is a steam boiler that generates water by heating water by combustion, and is an example in which the controlled object is the pressure of steam.

  The boiler system 1 includes a step value control boiler 2, a proportional control boiler 3, a control unit 4, a steam header 6, and a pressure sensor 7 that converts steam pressure in the steam header 6 into an electrical signal. The control unit 4 includes combustion position selection means for selecting the combustion position of the step value control boiler 3 and combustion ratio control means for determining the combustion amount of the proportional control boiler 3.

  The step value control boiler 2 controls the combustion amount by turning combustion on and off, or adjusting the size of the flame, and the combustion amount can be increased or decreased step by step according to the selected combustion position. The combustion amount at each combustion position is set to generate an amount of steam corresponding to the pressure difference P of the steam pressure (control target) in the steam header 6 to be controlled.

The boiler system 1 according to this embodiment includes three step value control boilers 2A, a step value control boiler 2B, a step value control boiler 2C, and one proportional control boiler 3.
Stage value control boilers 2A, 2B, 2C have a combustion amount of 1) combustion stop state (first combustion position)
2) Low combustion state L (second combustion position)
3) High combustion state H (third combustion position)
The so-called three-position control is made possible to control the combustion position in three stages.

In this embodiment, the increase / decrease amount of the combustion amount in the low combustion state L of the stage value control boilers 2A, 2B, 2C (corresponding to the combustion amount at the second combustion position, hereinafter referred to as the increase / decrease amount in the low combustion state L), high combustion The increase / decrease amount of the combustion amount in the state H (corresponding to the combustion amount at the time of transition from the low combustion state L to the high combustion state H, hereinafter referred to as the increase / decrease amount in the high combustion state H) is equal with respect to the control of the pressure difference P of the steam pressure Each of the combustion capacities (the amount of combustion in the high combustion state H) is set to be equal.
Here, the N position control represents that the combustion amount of the step value control boiler 2 can be controlled step by step to the N position including the combustion stop state.

  In addition, each of the stage value control boilers 2 is set in order of priority so as to be activated in the order of the stage value control boiler 2A, the stage value control boiler 2B, and the stage value control boiler 2C, and the activated stage value control boiler 2 is activated. Are sequentially shifted from the low combustion state L to the high combustion state H as necessary, and the stage value control boiler 2 of the next order is changed only when the stage value control boiler 2 having a high priority is in the high combustion state H. It is supposed to be activated.

The proportional control boiler 3 can continuously control the combustion amount in the range of 0% (no combustion) to 100% (maximum combustion amount) with respect to the combustion capacity (combustion amount in the maximum combustion state). By controlling the opening amount (combustion ratio) R of the proportional control valve, for example, the insufficient combustion amount defined by the difference between the required combustion amount and the combustion amount at the selected combustion position of the stage value control boiler 2 It comes to adjust.
In this embodiment, the combustion amount of the proportional control boiler 3 is obtained by the product of the combustion capacity of the proportional control boiler 3 and the valve opening (combustion ratio) R.

  Further, in this embodiment, the combustion capacity of the proportional control boiler 3 is set to 1.5 times the combustion amount in the low combustion state (second combustion position) L of the three stage value control boilers 2, Value control boiler stage value control boilers 2A, 2B, 2C increase / decrease amount of combustion at the combustion position selected in stages, that is, each stage value control boiler 2A, 2B, 2C increase / decrease amount in low combustion state L, and high It is set larger than any increase / decrease amount in the combustion state H.

The combustion amount of the step value control boiler 2 and the proportional control boiler 3 in this embodiment acts as an equal control amount with respect to the control of the pressure difference P.
In addition, when the combustion amount of the proportional control boiler 2 and the combustion amount of the proportional control boiler 3 do not act as the same control amount with respect to the control of the pressure difference P, the one combustion amount is converted into the other combustion amount and applied. Also good.

  In this embodiment, the case where the increase / decrease amount in the low combustion state L and the increase / decrease amount in the high combustion state H of each of the three stage value control boilers 2A, 2B, 2C will be described. When the combustion capacity of the three stage value control boilers 2A, 2B, and 2C, the increase / decrease amount in the low combustion state L, and the increase / decrease amount in the high combustion state H are different, the combustion capacity of the proportional control boiler 3 is The amount of increase / decrease in the low combustion state L of the stage value control boiler 2 is preferably set to be equal to or greater than the maximum amount of increase / decrease in the high combustion state H.

  The control unit 4 includes an input unit 4A that inputs an electric signal, a calculation unit 4B, an output unit 4C that outputs a control signal to the step value control boiler 2 and the proportional control boiler 3, and a database 4D, and selects a combustion position. And a combustion ratio control means. In this embodiment, the combustion position selection means is constituted by a calculation unit 4B and a database 4D, and the combustion ratio control means is constituted by a calculation unit 4B.

  A signal line 13 is connected to the input unit 4A, and an electric signal from the pressure sensor 7 is sent to the input unit 4A via the signal line 13 and input to the arithmetic unit 4B via the input unit 4A. It has become.

  The calculation unit 4B calculates the pressure difference P of the steam from the input electric signal from the pressure sensor 7, and compares the pressure difference P with the data table stored in the database 4D by the combustion position selection means, and the pressure difference The required combustion amount set corresponding to P and the combustion position of the stage value control boiler 2 for securing the required combustion amount (necessary stage value control boilers 2A, 2B, 2C, and respective combustion positions And the valve opening (combustion ratio) R of the proportional control boiler 3 is calculated from the required combustion amount and the combustion amount of the step value control boiler 2 at the selected combustion position by the combustion ratio control means. It has become.

  At this time, the combustion position of the step value control boiler 2 is selected so that the combustion amount of the step value control boiler 2 becomes the maximum within the range of the required combustion amount or less, and the combustion amount of the proportional control boiler is selected as the required combustion amount. The valve opening R is controlled so as to be equal to the insufficient combustion amount that is the difference from the combustion amount of the stage value control boiler 2 at the combustion position.

  The output unit 4C is connected to the signal line 14 to the step value control boilers 2A, 2B, 2C and the proportional control boiler 3, and the signal regarding the combustion position and the valve opening R calculated by the calculation unit 4B is a step value. It is transmitted to the control boilers 2A, 2B, 2C and the proportional control boiler 3.

In the database 4D, from the pressure difference P calculated by the calculation unit 4B, the calculation unit 4B relates to the required combustion amount and the combustion position of the step value control boiler 2, for example,
1) Pressure difference P
2) Necessary combustion amount corresponding to the pressure difference P 3) Data such as combustion states (combustion positions) and combustion amounts of the stage value control boilers 2A, 2B, 2C corresponding to the pressure difference P are stored as a data table. .
It is also possible to use data relating to the combustion ratio R of the proportional control boiler 3 by storing it in the database 4D in the same manner as 1) to 3).

The steam header 6 is connected to the upstream three stage value control boilers 2A, 2B, and 2C and the proportional control boiler 3 by the steam pipe 11, and is connected to the downstream steam use facility 20 by the steam pipe 12, The steam generated by the control boiler 2 and the proportional control boiler 3 is gathered to adjust the pressure difference and pressure fluctuation of the boilers 2 and 3 and supply steam to the steam using facility 20.
Further, the steam header 6 is provided with a pressure sensor 7 so that the steam pressure inside the steam header 6 is converted into an electric signal.
The steam use facility 20 is a facility that is operated by steam from the steam header 6.

Next, control of the boiler system 1 according to this embodiment will be described with reference to FIGS. 3 to 5.
FIG. 3 shows a pressure difference P (horizontal axis) with respect to a set value of the pressure of the steam header 6 and a required combustion amount corresponding to the pressure difference P (= total for satisfying the required combustion amount). Combustion state configuration (vertical axis) of the boilers 2 and 3 for securing the combustion amount Q), that is, the combustion state (no combustion, low combustion state, high combustion state) and proportional control of each stage value control boiler 2 The relationship of the valve opening degree R of the boiler 3 is shown.

  The total combustion amount Q corresponding to the pressure difference P of the steam header 6 is the total combustion when the pressure difference P is specified on the horizontal axis and a vertical line parallel to the vertical axis is drawn from the pressure difference P on the horizontal axis. It is shown at the position on the horizontal axis at the intersection with the straight line representing the quantity Q. The total combustion amount Q represents the configuration of the combustion state of the step value control boiler 2 and the combustion ratio of the proportional control boiler 3.

Also,
Total combustion quantity Q
= Combustion amount of each step value control boiler 2 (sum of combustion values of step value control boiler 2A, step value control boiler 2B, step value control boiler 2C) + combustion amount of proportional control boiler 3
An insufficient combustion amount, which is a difference between the total combustion amount Q and the combustion amount of the step value control boiler 2, is compensated by the combustion amount of the proportional control boiler 3.
The combustion amount of the proportional control boiler 3 is defined by the product of the combustion capacity of the proportional control boiler 3 and the valve opening degree R.

  Reference symbols P0 to P8 (P0 is a pressure difference = 0) indicate exemplary values of the pressure difference P in the steam header 6, but each pressure difference P (P = P1 to P7) is a level. The pressure difference P corresponds to the combustion amount when the value control boiler 2A is in the combustion stopped state, the low combustion state L and the high combustion state H of the step value control boilers 2A, 2B, and 2C are sequentially increased and decreased. The pressure difference P7 is equal to each other, and the pressure difference between P7 and P8 is ½ of the other pressure difference.

  The table shown in FIG. 4 shows the combustion state of each of the stage value control boilers 2A, 2B, 2C corresponding to the pressure difference P, the combustion stop state (first combustion position) as “−”, and the low combustion state L (2 The combustion position) is indicated as “low combustion”, and the high combustion state H (third combustion position) is indicated as “high combustion”.

  In the combustion control by the stage value control boiler 2 and the proportional control boiler 3 in the boiler system 1, as shown in FIG. 3, the combustion amount of the stage value control boiler 2 is required according to the pressure difference P (= The maximum combustion quantity Q) is selected so as to be the maximum in the range below, and the insufficient combustion quantity is adjusted by the valve opening degree R of the proportional control boiler 3.

Therefore, when the pressure difference P is small and the combustion amount in the low combustion state L of the step value control boiler 2 exceeds the required combustion amount, the proportional control boiler 3 is started prior to the step value control boiler 2. The step value control boiler 2 is activated only when the pressure difference P becomes larger than P1 + 0.5P1 (= P1 + 0.5P1).
When the pressure difference P is P1 + 0.5P1, the step value control boilers 2A, 2B, 2C are in the combustion stop state “−”.

When the pressure difference P reaches P1 + 0.5P1, the valve opening R1 of the proportional control boiler 3 becomes 100%. When the pressure difference P becomes larger than P1 + 0.5P1, the step value control boiler 2A is activated and burns in the low combustion state L. To do.
When combustion in the low combustion state L of the step value control boiler 2A is started, the valve opening R1 of the proportional control boiler 3 is insufficient by subtracting the combustion amount in the low combustion state L of the step value control boiler 2A from the necessary combustion amount. The valve opening R2 corresponding to the combustion amount is controlled.

Next, when the pressure difference P is equal to or less than the pressure difference P3 + 0.5P1, the combustion ratio R3 of the proportional control boiler 3 is increased, so that the required combustion amount and the combustion amount in the low combustion state L of the stage value control boiler 2A are reduced. When the difference is compensated by the proportional control boiler 3 and the pressure difference P reaches the pressure difference P3 + 0.5P1, the combustion ratio R3 becomes 100%.
Next, when the pressure difference P becomes larger than the pressure difference P3 + 0.5P1, the combustion in the high combustion state H of the step value control boiler 2A is started, and the valve opening degree R3 of the proportional control boiler 3 is step value controlled from the total combustion amount Q. The valve opening is reduced to the valve opening obtained by subtracting the combustion amount in the high combustion state H of the boiler 2A.
Thereafter, the same control is repeated when the pressure difference P is between the pressure difference P4 + 0.5P1 and the pressure difference P8 (= P7 + 0.5P1).

Next, the control method of the boiler system 1 which concerns on this embodiment is demonstrated with reference to FIGS.
1) The pressure in the steam header 6 is converted into an electric signal by the pressure sensor 7 and input to the arithmetic unit 4B via the input unit 4A of the control unit 4.
Based on the electric signal, a pressure difference PW with respect to the set pressure (set value) of the steam in the steam header 6 is calculated.
2) The calculation unit 4B collates the pressure difference PW with the data table stored in the database 4D by the combustion position selection means, and calculates the required combustion amount set corresponding to the pressure difference P and the required combustion amount. The combustion position at the combustion position of the stage value control boiler 2 for securing the stage value control boiler 2A is the high combustion state H (third combustion position), and the stage value control boiler 2B is the low combustion state L (second combustion position). The stage value control boiler 2C is acquired to be in the combustion stopped state (first combustion position), and the combustion position of the stage value control boiler 2 is selected.
3) Next, the combustion ratio control means of the calculation unit 4B calculates an insufficient combustion amount from the required combustion amount and the combustion amount of the stage value control boiler 2 at the selected combustion position, and this insufficient combustion amount and proportional control are calculated. A valve opening RW at which the combustion amount of the boiler 3 becomes equal is calculated.
The valve opening RW is calculated as follows: insufficient combustion amount = combustion capacity of the proportional control boiler 3 × valve opening RW
In this embodiment, the valve opening RW is 100%.
4) Next, selection data relating to the combustion position of the stage value control boiler 2 in which the stage value control boiler 2A is in the high combustion state H, the stage value control boiler 2B is in the low combustion state L, and the stage value control boiler 2C is in the combustion stop state. And the data related to the valve opening RW of the proportional control boiler 3 are sent as control signals from the calculation unit 4B to the respective step value control boilers 2A, 2B, 2C and the proportional control boiler 3 via the output unit 4C. The value control boilers 2A, 2B, 2C and the proportional control boiler 3 are controlled.

  According to the boiler system 1 according to this embodiment, the combustion capacity of the proportional control boiler 3 is set to 1.5 times the combustion amount in the low combustion state L of the step value control boiler 2, so that the step value control By selecting the combustion amount of the boiler 2 as the maximum combustion position within the range of the required combustion amount or less, the short combustion amount can always be adjusted by controlling the valve opening R of the proportional control boiler 3, for example, The combustion amount corresponding to the low combustion state L of the step value control boiler 2C can be obtained without starting the step value control boiler 2C.

  As a result, when the elapsed time (t) is the horizontal axis and the combustion amount of the step value control boiler 2 and the proportional control boiler 3 is the vertical axis, as shown in FIG. Necessary combustion by steady combustion by the combustion amount in the combustion state H, the combustion amount in the low combustion state L of the step value control boiler 2B, and the combustion amount in the combustion capacity (combustion ratio RW = 100%) of the proportional control boiler 3 The amount can be secured and the start and stop of the step value control boiler 2 can be suppressed.

  As a result, purge loss when the step value control boiler 2 is started is reduced, soot generation is suppressed when the step value control boiler 2 is started, and soot is accumulated in the heat transfer portion of the step value control boiler 2. As a result, a decrease in heat transfer efficiency and device deterioration due to the operation are suppressed, and the service life is extended.

Further, when the boiler system 1 is started up, the short combustion amount can be adjusted by controlling the combustion amount of the proportional control boiler 3, so that the total combustion amount Q is, for example, as shown in FIG. Even when the stage value control boiler 2B suddenly fluctuates across the high combustion state H, the stage value control boiler 2C can be controlled without starting and stopping.
Therefore, control in which a part of the combustion of the proportional control boiler 3 is transferred to the stage value control boiler 2 in a stable state, such that the stage value control boiler 2C is started and burned after the severe load fluctuation is eliminated and the load is stabilized. It is also possible to do.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention.
For example, in the above-described embodiment, three step value control boilers 2 and one proportional control boiler 3 are provided, and the increase / decrease amount in the low combustion state L of the three step value control boilers 2A, 2B, 2C is high. Although the case where the increase / decrease amount and the combustion capacity are equal in the combustion state H has been described, the number of stage value control boilers 2, the increase / decrease amount in each combustion state, the combustion capacity, the startup priority, and the number of proportional control boilers 3 are arbitrarily set. Is possible.

  Moreover, in the said embodiment, although the case where the step value control boiler 2 and the proportional control boiler 3 were steam boilers was demonstrated, while applying the step value control boiler 2 and the proportional control boiler 3 to a hot water boiler, it is controlled object May be the temperature of hot water.

  In the above embodiment, the case of the boiler system 1 in which the combustion capacity of the proportional control boiler 3 is set larger than the increase / decrease amount in each combustion state of the step value control boiler 2 has been described. If any of the quantity is set larger than the steam supply capacity of the proportional control boiler 3 and the insufficient combustion amount cannot be adjusted by the valve opening R of the proportional control boiler 3, the step value control boiler 2 is started. It may be adjusted by stopping.

It is a figure showing an outline of composition of a boiler system concerning one embodiment of the present invention. It is a figure which shows the relationship between the step value control boiler and the proportional control boiler, and the combustion amount in the boiler system which concerns on one Embodiment of this invention. It is a figure which shows the relationship between the required combustion amount of the boiler system which concerns on one Embodiment of this invention, and the structure of the combustion state of each boiler. It is a figure which shows the relationship between the pressure difference of the boiler system which concerns on one Embodiment of this invention, and the combustion state of a step value control boiler. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the effect | action of the boiler system which concerns on one Embodiment of this invention, Comprising: (A) is (A) is the relationship of the required combustion amount and boiler combustion in a steady state, (B) is a load. It is a figure which shows the effect | action at the time of a fluctuation | variation.

Explanation of symbols

L Low combustion state (2nd combustion position)
H High combustion state (third combustion position)
Q Total combustion amount R Valve opening (combustion ratio)
DESCRIPTION OF SYMBOLS 1 Boiler system 2, 2A, 2B, 2C Stage value control boiler 3 Proportional control boiler 4 Control part 6 Steam collecting part 7 Pressure sensor 20 Steam use equipment

Claims (3)

A step value control boiler in which the amount of combustion can be increased or decreased stepwise according to the selected combustion position;
With a proportional control boiler that can continuously increase or decrease the combustion amount,
A boiler control method for adjusting a control target consisting of steam pressure or water temperature according to a combustion amount,
The combustion position of the step value control boiler,
Select so that the combustion amount of the step value control boiler is maximized in the range below the required combustion amount required according to the variation of the control target,
A boiler control method characterized in that an insufficient combustion amount, which is a difference between the required combustion amount and a combustion amount of the stage value control boiler at the selected combustion position, is compensated by combustion of the proportional control boiler. A boiler system that includes a plurality of boilers and that controls a control target composed of steam pressure or water temperature by adjusting a combustion amount of the plurality of boilers,
A step value control boiler in which the amount of combustion can be increased or decreased stepwise according to the selected combustion position;
A proportional control boiler whose combustion amount can be increased or decreased continuously;
Combustion position selection means for selecting the combustion position of the stage value control boiler;
Combustion ratio control means for determining the combustion amount of the proportional control boiler,
The combustion position selection means includes
Selecting the combustion position at which the combustion amount of the step value control boiler is the maximum value within a range equal to or less than the required combustion amount required according to the variation of the control target;
The combustion ratio control means includes
The combustion amount of the proportional control boiler is
A boiler system, wherein a combustion ratio is adjusted so that an insufficient combustion amount that is a difference between the necessary combustion amount and a combustion amount of the stage value control boiler at the selected combustion position is obtained. The boiler system according to claim 2,
The combustion amount in the maximum combustion of the proportional control boiler is:
The boiler system characterized in that it is equal to or greater than the maximum amount of the increase / decrease amount of the combustion position selected stepwise of the step value control boiler.

Images