JP6879089B2 - Boiler system - Google Patents

Description

The present invention comprises a first boiler group having one or more boilers whose combustion rate is determined so that the header pressure value falls within a preset control pressure band, and a target steam pressure value with a preset steam pressure value. The present invention relates to a boiler system including a boiler group consisting of a second boiler group having one or more boilers that do not belong to the first boiler group and whose combustion rate is determined so as to be.

Conventionally, as a boiler, a step value control boiler capable of increasing or decreasing the combustion amount stepwise according to a selected combustion position and a continuous control boiler capable of continuously increasing or decreasing the combustion amount are known.
In a boiler system consisting of a boiler group consisting of one or more stage value control boilers, when controlling the combustion state of each stage value control boiler, the header pressure is set by setting the maximum set pressure value and control width in advance. The control target is controlled so that the steam pressure value inside the steam header (hereinafter, also referred to as "header pressure value") that determines the control pressure band to be stabilized and collects the steam generated by the boiler group is within the control pressure band. Control the amount of boiler burned.
More specifically, the amount of combustion of the boiler decreases as the header pressure value moves to the high pressure side of the control pressure band, and conversely, the amount of combustion of the boiler increases as the header pressure value moves to the low pressure side of the control pressure band. The combustion state is controlled.
In the step value control boiler group, it is known that, for example, a proportional distribution control method is applied to calculate the required steam amount based on the header pressure value (see, for example, Patent Document 1).

On the other hand, in a boiler system composed of a boiler group consisting of one or more continuous control boilers, when controlling the combustion state of each continuous control boiler, a target steam pressure value is set in advance and the header pressure value is set as the target steam. It is known to control the number of boilers to be controlled by calculating the control amount according to the deviation between the header pressure value and the target steam pressure value so as to keep the pressure value (for example, patent). Reference 2).

In recent years, a continuous control boiler group (second boiler group) may be added to the same steam line with respect to the step value control boiler group (first boiler group).
In such a case, in the step value control boiler group (first boiler group), as described above, the combustion amount of the boiler to be controlled is controlled so that the header pressure value falls within the preset control pressure band. On the other hand, the continuous control boiler group (second boiler group) is controlled so that the header pressure value maintains the preset target steam pressure value as described above.
Therefore, the stage value control boiler group (first boiler group) in which the combustion amount is controlled so that the header pressure value falls within the control pressure band, and the combustion amount are controlled so that the header pressure value maintains the target steam pressure value. When a number of control boiler groups with different control methods are mixed in the same steam line as in the continuous control boiler group (second boiler group), the header pressure value is set in the continuous control boiler group (second boiler group). Since the control is performed so as to maintain the set target steam pressure value, the operating rate of the step value control boiler group (first boiler group) is determined based on the target steam pressure value.

That is, the continuous control boiler group (second boiler group) fluctuates the combustion amount (generated steam amount) in response to the change in the header pressure due to the fluctuation of the total steam load, so that the header pressure value sets the target steam pressure value. Performs a follow-up operation to keep it. On the other hand, the step value control boiler group (first boiler group) operates to output a constant amount of steam determined by the target steam pressure value as long as the header pressure value maintains the target steam pressure value.

Then, when the total steam load is reduced (that is, when the total combustion rate is reduced), the combustion rate of the entire continuous control boiler group (second boiler group) may be 0%. On the contrary, when the total steam load rises (that is, when the total combustion rate rises), the combustion rate of the entire continuous control boiler group (second boiler group) may reach 100%.
When the overall steam load decreases, the combustion rate of the entire continuous control boiler group (second boiler group) becomes 0%, and the overall steam load further decreases, the step value control boiler group (first boiler group) becomes the entire. Since the operation follows the load, the header pressure value fluctuates. Similarly, when the overall steam load increases, the combustion rate of the entire continuous control boiler group (second boiler group) becomes 100%, and the overall steam load further increases, the step value control boiler group (first boiler group) ) Follows the overall load, so the header pressure value fluctuates.
Therefore, the stage value control boiler group (first boiler group) in which the combustion amount is controlled so that the header pressure value falls within the control pressure band, and the combustion amount are controlled so that the header pressure value maintains the target steam pressure value. When the continuous control boiler group (second boiler group) coexists, it is desired to secure a wide band of the overall combustion rate capable of keeping the header pressure value constant at the target pressure value. By doing so, even if the overall steam load decreases (that is, the overall combustion rate decreases) or conversely, the overall steam load increases (that is, the overall combustion rate increases). , The header pressure value can be maintained at the target steam pressure value.

Japanese Unexamined Patent Publication No. 2011-208817 Japanese Unexamined Patent Publication No. 2010-48462

Therefore, in a boiler system in which a step value control boiler group (first boiler group) and a continuous control boiler group (second boiler group) are mixed, when the overall steam load decreases (that is, when the overall combustion rate decreases). Even if the total steam load rises (that is, the overall combustion rate rises), it is desirable to control the number of units so that the header pressure value can be maintained at the target steam pressure value as much as possible. ..

The present invention comprises a first boiler group having one or more boilers whose combustion rate is controlled so that the header pressure value falls within a preset control pressure band, and a target steam pressure value with a preset header pressure value. In a boiler system including a boiler group consisting of a second boiler group having one or more boilers that do not belong to the first boiler group and whose combustion rate is controlled so as to maintain the above, when the total steam load is reduced (that is, the whole). The header pressure value can be maintained at the target steam pressure value regardless of whether the overall steam load increases (that is, the overall combustion rate increases) even when the combustion rate decreases). The purpose is to provide a boiler system.

(1) The present invention includes a boiler group consisting of a first boiler group consisting of one or more boilers and a second boiler group consisting of one or more boilers that do not belong to the first boiler group.
A steam header that collects the steam generated in the boiler group,
A vapor pressure measuring means for measuring the vapor pressure inside the steam header, and
A control unit that controls the combustion state of the boiler group,
It is a boiler system equipped with
The control unit
The measured vapor pressure value, which is the vapor pressure value measured by the vapor pressure measuring means, falls within the range of the control pressure band defined by the preset control width with the preset maximum set pressure value as the upper limit value. As described above, the first control unit that controls the combustion state of the first boiler group and
A second control unit that controls the combustion state of the second boiler group so as to keep the steam pressure value measured by the steam pressure measuring means at a set target steam pressure value.
A combustion amount acquisition unit that acquires the overall combustion rate of the second boiler group, and
Whether or not the state in which the total combustion rate of the second boiler group acquired by the combustion amount acquisition unit exceeds the preset upper limit combustion rate or the state in which the upper limit combustion rate is equal to or higher continues for the preset first time. Upper limit judgment unit for judgment and
Whether or not the state in which the overall combustion rate of the second boiler group acquired by the combustion amount acquisition unit is below the preset lower limit combustion rate or the state in which it is below the lower limit combustion rate continues for the preset second time. Lower limit judgment unit for judgment and
When it is determined by the upper limit determination unit that the state in which the overall combustion rate of the second boiler group exceeds the upper limit combustion rate or the state in which the upper limit combustion rate is equal to or higher than the upper limit combustion rate continues for the first hour, the control pressure band By changing the range, the overall combustion rate of the first boiler group is increased, and the overall combustion rate of the second boiler group is below the lower limit combustion rate or below the lower limit combustion rate by the lower limit determination unit. Is determined to continue for the second time, the control pressure band correction unit (for example, "control" described later) that lowers the overall combustion rate of the first boiler group by changing the range of the control pressure band. It relates to a boiler system including "pressure band correction unit 44" or "control pressure band designation unit 45").

(2) In the boiler system of (1), a control upper limit pressure value which is an upper limit value of the maximum set pressure value is set in advance, and the control pressure band correction unit (for example, "control pressure band correction" described later will be described. In "Part 44"), it is determined by the upper limit determination unit that the state in which the overall combustion rate of the second boiler group exceeds the upper limit combustion rate or is equal to or higher than the upper limit combustion rate continues for the first hour. In that case, when the maximum set pressure value exceeds the control upper limit pressure value, the control width of the control pressure band is narrowed while keeping the maximum set pressure value as it is, and the control is performed even if the maximum set pressure value is increased. When the upper limit pressure value is not exceeded, the control width of the control pressure band is kept as it is, the maximum set pressure value is increased so as not to exceed the control upper limit pressure value, and the lower limit determination unit determines the second boiler group. When it is determined that the state in which the total combustion rate of the above lower limit combustion rate is lower than the lower limit combustion rate or the state in which the lower limit combustion rate is lower than the lower limit combustion rate continues for the second time, the control width of the control pressure band is adjusted while keeping the maximum set pressure value as it is. The maximum set pressure value may be lowered while expanding or keeping the control width of the control pressure band as it is.

(3) In the boiler system of (1), the first control unit sets a plurality of preset maximum set pressure values as the respective upper limit values, and a plurality defined by a preset control width for each. The measured steam pressure value, which is the steam pressure value measured by the steam pressure measuring means, is obtained by setting the control pressure band of any one of the plurality of control pressure bands. The combustion state of the first boiler group is controlled so as to be within the range of any one of the set control pressure bands, and the control pressure band correction unit (for example, "control pressure" described later) is used. In the band designation unit 45 ”), the state in which the overall combustion rate of the second boiler group exceeds the upper limit combustion rate or exceeds the upper limit combustion rate continues for the first hour by the upper limit determination unit. When it is determined, the control pressure band of the plurality of control pressure bands is changed so as to increase the combustion rate of the first boiler group instead of the control pressure band of any one of the plurality of control pressure bands set. Another control pressure band is set, and the state in which the overall combustion rate of the second boiler group is below the lower limit combustion rate or below the lower limit combustion rate is continued for the second time by the lower limit determination unit. When is determined, the control pressure band of the plurality of control pressure bands is changed so as to reduce the combustion rate of the first boiler group in place of the control pressure band of any one of the plurality of control pressure bands set. Another control pressure band of may be set.

(4) Further, the present invention comprises a first boiler group consisting of one or more boilers capable of burning at a plurality of stepwise combustion positions, and a first boiler group consisting of one or more boilers not belonging to the first boiler group. A boiler group consisting of two boiler groups, a steam header for collecting the steam generated in the boiler group, a steam pressure measuring means for measuring the steam pressure inside the steam header, and a combustion state of the boiler group are controlled. A boiler system including a control unit for controlling the amount of steam of any boiler belonging to the first group of boilers, which is the difference between the amount of steam at an arbitrary combustion position and the amount of steam at a combustion position one level below it. It is regarded as a set of virtual boilers virtualized in the boiler, and the control unit presets the measured steam pressure value, which is the steam pressure value measured by the steam pressure measuring means, with the preset maximum set pressure value as the upper limit value. The first control unit that controls the combustion state of the first boiler group and the steam pressure value measured by the steam pressure measuring means are set so as to fall within the range of the control pressure band defined by the determined control width. A second control unit that controls the combustion state of the second boiler group so as to maintain the target steam pressure value, a combustion amount acquisition unit that acquires the overall combustion rate of the second boiler group, and a combustion amount acquisition unit. An upper limit determination unit for determining whether or not the acquired overall combustion rate of the second boiler group exceeds the preset upper limit combustion rate or the state where the upper limit combustion rate is equal to or higher than the preset upper limit combustion rate continues for the preset first time. Whether or not the state in which the overall combustion rate of the second boiler group acquired by the combustion amount acquisition unit is below the preset lower limit combustion rate or the state in which it is below the lower limit combustion rate continues for the preset second time. The lower limit determination unit and the upper limit determination unit determine that the state in which the overall combustion rate of the second boiler group exceeds the upper limit combustion rate or exceeds the upper limit combustion rate continues for the first hour. In this case, the maximum number of virtual boilers to be controlled by combustion included in the first boiler group is increased, and the lower limit determination unit determines that the overall combustion rate of the second boiler group is lower than the lower limit combustion rate or the lower limit combustion. When it is determined that the state of being equal to or less than the rate continues for the second time, a virtual boiler number correction unit for reducing the maximum number of virtual boilers subject to combustion control included in the first boiler group is provided. Regarding the boiler system.

(5) Further, the present invention includes a boiler group consisting of a first boiler group consisting of one or more boilers, a second boiler group consisting of one or more boilers that do not belong to the first boiler group, and the boiler. A steam header that collects the steam generated in the group, a steam pressure measuring means that measures the steam pressure inside the steam header, and a plurality of preset maximum set pressure values are set as upper limit values for each. It has a plurality of control pressure bands defined by a preset control width, and is measured by the steam pressure measuring means by setting a control pressure band of any one of the plurality of control pressure bands. The first control that controls the combustion state of the first boiler group so that the measured steam pressure value, which is the steam pressure value, falls within the range of any one of the set control pressure bands. A boiler system including a unit and a second control unit that controls the combustion state of the second boiler group so as to keep the steam pressure value measured by the steam pressure measuring means at a set target steam pressure value. In the second control unit, the combustion amount acquisition unit that acquires the total combustion rate of the second boiler group and the upper limit of the total combustion rate of the second boiler group acquired by the combustion amount acquisition unit are set in advance. An upper limit determination unit that determines whether or not a state that exceeds the combustion rate or a state that exceeds the upper limit combustion rate continues for a preset first time, and a total combustion of the second boiler group acquired by the combustion amount acquisition unit. The second lower limit determination unit determines whether or not the state where the rate is below the preset lower limit combustion rate or the state where the rate is below the lower limit combustion rate continues for the preset second time, and the upper limit determination unit. When it is determined that the state in which the total combustion rate of the boiler group exceeds the upper limit combustion rate or the state in which the upper limit combustion rate is equal to or higher than the upper limit combustion rate continues for the first time, the setting is made for the first control unit. Instead of the control pressure band of any one of the plurality of control pressure bands, another control pressure band of the plurality of control pressure bands is set so as to increase the combustion rate of the first boiler group. When it is determined by the lower limit determination unit that the overall combustion rate of the second boiler group is below the lower limit combustion rate or below the lower limit combustion rate for the second time. With respect to the first control unit, the plurality of control pressures are changed so as to reduce the combustion rate of the first boiler group in place of any one of the set control pressure bands. Set another control pressure band within the band The present invention relates to a boiler system including a control pressure band correction unit, which is instructed to do so.

(6) In the boiler system according to (1) to (5), the upper limit combustion rate and the lower limit combustion rate are eco-driving zones in which the boiler efficiency of the boiler included in the second boiler group is higher than a predetermined threshold value. Can be included in the range of.

According to the boiler system of the present invention, when the total steam load of the boiler system is reduced (that is, the total combustion rate is reduced) in the step value control boiler group (first boiler group) and the continuous control boiler group (second boiler group). Boiler system that can maintain the header pressure at the target steam pressure value regardless of whether the total steam load of the boiler system rises (that is, the total combustion rate rises). Can be provided.

It is a figure which shows the outline of the boiler system 1 which concerns on this embodiment. It is a functional block diagram of the control unit 4 in 1st Embodiment. It is a figure which shows the change of the total combustion rate and the header pressure value of the 2nd boiler group 2B when the total steam load is lowered when the combustion is controlled by the normal method. It is a figure which shows the change of the total combustion rate and the header pressure value of the 2nd boiler group 2B when the total steam load rises in the case of combustion control by a normal method. It is a figure which shows the change of the total combustion rate and the header pressure value of the 2nd boiler group 2B when the total steam load is lowered when the combustion is controlled by the method which concerns on 1st Embodiment. It is a figure which shows the change of the total combustion rate and the header pressure value of the boiler system 1 when the total steam load rises when the combustion is controlled by the method which concerns on 1st Embodiment. It is a functional block diagram of the control unit 4 in the 2nd Embodiment. It is a figure which shows the change of the total combustion rate and the header pressure value of the 2nd boiler group 2B when the total steam load is lowered when the combustion is controlled by the method which concerns on 2nd Embodiment. It is a figure which shows the change of the total combustion rate and the header pressure value of the 2nd boiler group 2B when the total steam load rises when the combustion is controlled by the method which concerns on 2nd Embodiment. It is a functional block diagram of the control unit 4 in the 3rd Embodiment. It is a figure which shows the change of the total combustion rate and the header pressure value of the 2nd boiler group 2B when the total steam load is lowered when the combustion is controlled by the method which concerns on 3rd Embodiment. It is a figure which shows the change of the total combustion rate and the header pressure value of the 2nd boiler group 2B when the total steam load rises when the combustion is controlled by the method which concerns on 3rd Embodiment. It is a figure which shows the outline of the boiler system 1 which concerns on the modification of 1st Embodiment. It is a figure which shows the outline of the boiler system 1 which concerns on the modification of 2nd Embodiment. It is a figure which shows the outline of the boiler system 1 which concerns on the modification of 3rd Embodiment. It is a figure which shows the outline of the boiler system 1 which concerns on the modification of 1st Embodiment. It is a figure which shows the outline of the boiler system 1 which concerns on the modification of 2nd Embodiment. It is a figure which shows the outline of the boiler system 1 which concerns on the modification of 3rd Embodiment.

First, the overall configuration of the boiler system 1 according to the first embodiment of the present invention will be described with reference to FIG.

The boiler system 1 includes a first boiler group 2A composed of one or a plurality of step value control boilers 20A, a second boiler group 2B composed of one or a plurality of continuous control boilers 20B, and a boiler group 2 composed of one or a plurality of continuous control boilers 20B. , The steam header 6 that collects the steam generated in the first boiler group 2A and the second boiler group 2B, the steam pressure sensor 7 that measures the pressure inside the steam header 6, and the combustion state of the first boiler group 2A. A unit control device 3 having a control unit 4 including a first control unit 4A for controlling the above and a second control unit 4B for controlling the combustion state of the second boiler group 2B is provided.
The first boiler group 2A according to the first embodiment is composed of two stage value control boilers 20A, and the second boiler group 2B is composed of two continuous control boilers 20B. It is not limited. The number of step value control boilers 20A and the number of continuous control boilers 20B can be appropriately set.

As shown in FIG. 1, the step value control boiler 20A and the continuous control boiler 20B control the combustion state of the boiler main body 21A and the boiler main body 21B on which combustion is performed, and the step value control boiler 20A and the continuous control boiler 20B, respectively. It includes a local control unit 22A and a local control unit 22B.

The local control unit 22A and the local control unit 22B change the combustion state of the step value control boiler 20A and the continuous control boiler 20B, respectively, according to the amount of steam consumed. Specifically, the local control unit 22A and the local control unit 22B have step values based on the control signals transmitted from the first control unit 4A and the second control unit 4B via the signal line 16A and the signal line 16B, respectively. The combustion state of the control boiler 20A and the continuous control boiler 20B is controlled. Further, the local control unit 22A and the local control unit 22B control the signals used by the first control unit 4A and the second control unit 4B, respectively, via the signal line 16A and the signal line 16B to the first control unit 4A and the second control unit 4A. It is transmitted to the part 4B. Examples of the signals used by the first control unit 4A and the second control unit 4B include the actual combustion state of the step value control boiler 20A and the continuous control boiler 20B, and other data.

The boiler group 2 generates steam to be supplied to the steam use equipment 18.
The steam header 6 is connected to the step value control boiler 20A and the continuous control boiler 20B constituting the boiler group 2 via the steam pipe 11. The downstream side of the steam header 6 is connected to the steam use facility 18 via a steam pipe 12.
The steam header 6 adjusts the mutual pressure difference and pressure fluctuation between the step value control boiler 20A and the continuous control boiler 20B by collecting and storing the steam generated in the boiler group 2, and the pressure is adjusted steam. Is supplied to the steam use equipment 18.

The vapor pressure sensor 7 is electrically connected to the first control unit 4A and the second control unit 4B via the signal line 13. The vapor pressure sensor 7 measures the vapor pressure inside the steam header 6 (the pressure of the steam generated in the boiler group 2), and transmits the signal (vapor pressure signal) related to the measured vapor pressure via the signal line 13. It transmits to the first control unit 4A and the second control unit 4B.
The first control unit 4A and the second control unit 4B control the combustion state of the step value control boiler 20A and the continuous control boiler 20B based on the steam pressure inside the steam header 6 measured by the steam pressure sensor 7.

In the above boiler system 1, the steam generated in the boiler group 2 can be supplied to the steam use facility 18 via the steam header 6.

Next, the first boiler group 2A composed of the step value control boiler 20A and the second boiler group 2B composed of the continuous control boiler 20B will be described.
First, the first boiler group 2A including the step value control boiler 20A will be described.

<Step value control boiler 20A>
The step value control boiler 20A controls the amount of combustion by selectively turning on / off the combustion or adjusting the size of the flame, and changes the amount of combustion stepwise according to the selected combustion position. It is a boiler that can be increased or decreased.

The stage value control boiler 20A provided in the boiler system 1 is, for example, a boiler in which the combustion state (combustion position, combustion rate) can be controlled in the following three stages, so-called three-position control.
1) Combustion stop position (combustion rate 0%)
2) Low combustion position L (for example, set at 50% of the maximum combustion amount)
3) High combustion position H (combustion rate 100% (maximum combustion amount)).
For example, when the combustion amount in the combustion state (high combustion state) at the high combustion position H of the step value control boiler 20A is 2000 kg / h, the combustion amount at the low combustion position L is 1000 kg / h.

<Virtual boiler>
In general, the step value control boiler can be regarded as a set of virtual boilers imagining the difference steam amount between the amount of steam at an arbitrary combustion position and the amount of steam at a combustion position one level below it.
The three-position control step value control boiler 20A can be regarded as being composed of two virtual boilers, a low combustion amount boiler and a (high combustion amount-low combustion amount) boiler. Hereinafter, for simplicity, a low combustion amount boiler is referred to as a low combustion virtual boiler (also referred to as "L boiler" for simplicity), and a (high combustion amount-low combustion amount) boiler is referred to as a high combustion virtual boiler (for simplicity, "H"). Also called "boiler"). For example, in the case of the above-mentioned step value control boiler 20A, the step value control boiler 20A has two virtual boilers, a low combustion virtual boiler (maximum combustion amount 1000 kg / h) and a high combustion virtual boiler (maximum combustion amount 1000 kg / h). Can be considered to consist of.
By doing so, when the number of boilers to be controlled by combustion is set, it can be set in units of virtual boilers. Further, when selecting a boiler that gives a combustion instruction or a combustion stop instruction, it can be selected in units of virtual boilers.

As the step value control boiler 20A, in addition to the three-position control, any N-position control, for example, the combustion amount is the combustion stop position (first combustion position), the low combustion position L (second combustion position), and the medium combustion position M. The so-called four-position control, which can be controlled to four stages of combustion positions (third combustion position) and high combustion position H (fourth combustion position), five positions or more, or two positions may be used. The boiler capacity of each stage value control boiler 20A, the number of stages of combustion positions, the combustion rate at each combustion position, and the like may be different for each stage value control boiler 20A.

<Proportional distribution control method>
Next, the control of the first boiler group 2A including the step value control boiler 20A will be described.
The first control unit 4A determines the control pressure band by setting the _{maximum set pressure value P max and the control width P1 in advance.} Here, the control pressure band refers to a pressure band having a control width with the _{maximum set pressure value P max as the upper limit.} The lower limit of the control pressure band is the minimum permissible value of pressure, and is also referred to as the _{minimum set pressure value P min.}
The first control unit 4A _{calculates the required steam amount JN based on the pressure deviation PD (difference between the maximum set pressure value P max} and the header pressure value) of the header pressure value, and burns each stage value control boiler 20A. By selecting the position and controlling the combustion state of the step value control boiler 20A, the header pressure value is kept within the control pressure band. The combustion position of each stage value control boiler 20A is selected, for example, based on a preset priority.

Specifically, the first control unit 4A controls, for example, as follows.
The first control unit 4A is generated in the boiler according to the required load based on the ratio PR1 obtained by dividing the pressure deviation PD of the header pressure value by the control pressure width P1 (= P _max −P _{min) for each control cycle.} The power steam amount (hereinafter, also referred to as "required steam amount JN") is calculated by Equation 1.
Required steam amount JN = Maximum steam amount JG x PR1 ... (Equation 1)
Here, the maximum steam amount JG is the total amount of steam (maximum steam amount) in the maximum combustion state of each of the boilers 20A constituting the first boiler group 2A.
For example, in the example of the first boiler group 2A composed of two step value control boilers 20A (maximum steam amount 2000 kg / h), the maximum steam amount JG = 4,000 kg / h. When the header pressure value is _{an intermediate pressure value between the maximum set pressure value P max} and the minimum set pressure value P _min , the required steam amount is 2,000 kg / h.

The first control unit 4A calculates the output steam amount JT output by the first boiler group 2A for each control cycle, for example, based on the combustion state of each boiler 20A transmitted from the local control unit 22A.

The first control unit 4A selects the combustion position of each step value control boiler 20A based on the deviation amount between the required steam amount JN and the output steam amount JT calculated for each control cycle and the fluctuation state of the header pressure value. Therefore, the combustion state can be controlled.

The first control unit 4A repeatedly executes the combustion control process in the control cycle.
By doing so, the combustion position of each step value control boiler 20A is selected so that the smaller the required load, that is, the higher the header pressure value, the smaller the combustion amount. Further, the combustion position of each step value control boiler 20A is selected so that the amount of combustion increases as the required load increases, that is, as the header pressure value decreases.
As described above, in the number control (proportional distribution control method) in the first boiler group 2A, the combustion rate of the entire first boiler group 2A is determined by the header pressure value.

In the control of the amount of steam by the proportional distribution control method, from the viewpoint of emphasizing pressure stability, a control upper limit pressure value which is a value equal to or higher than the _{maximum set pressure value P max is set in advance, and the header pressure is the control upper limit.} When the pressure value is exceeded, the number of boilers may be controlled so that all boilers are in a combustion stopped state (also referred to as "standby for all units"). Therefore, as will be described later, when raising the maximum set pressure value, it is necessary not to exceed the control upper limit pressure value.
The first boiler group 2A including the step value control boiler 20A has been described above.

<About continuous control boiler 20B>
Next, the second boiler group 2B including the continuous control boiler 20B will be described.
The continuous control boiler 20B included in the boiler system 1 continuously controls the combustion amount at least in the range from the minimum combustion state S1 (for example, the combustion state at a combustion amount of 20% of the maximum combustion rate) to the maximum combustion state S2. It is a possible boiler. The continuous control boiler 20B adjusts the combustion amount by controlling, for example, the opening degree (combustion ratio) of the valve that supplies fuel to the burner and the valve that supplies combustion air.

Further, the continuous control of the combustion amount means that the operations and signals in the local control unit 22B are handled in stages in a digital manner (for example, the output (combustion amount) of the continuous control boiler 20B is in 1% increments). Even if it is controlled), it includes the case where the output can be controlled virtually continuously.

The change in the combustion state between the combustion stop state S0 of the continuous control boiler 20B and the minimum combustion state S1 is controlled by turning on / off the combustion of the continuous control boiler 20B (burner). Then, in the range from the minimum combustion state S1 to the maximum combustion state S2, the combustion amount can be continuously controlled.
More specifically, in the continuous control boiler 20B, a unit steam amount U, which is a unit of a variable steam amount, is set. As a result, the continuous control boiler 20B can change the steam amount in units of the unit steam amount U in the range from the minimum combustion state S1 to the maximum combustion state S2.

The unit steam amount U can be appropriately set according to the steam amount (maximum steam amount) in the maximum combustion state S2 of the continuously controlled boiler 20B, but from the viewpoint of improving the followability of the output steam amount in the boiler system to the required steam amount, It is preferably set to 0.1% to 20% of the maximum steam amount of the continuously controlled boiler 20B, and more preferably set to 1% to 10%.

<PI or PID control method>
The second control unit 4B is included in the second boiler group 2B by known PI control or PID control based on the deviation amount between the header pressure value calculated for each control cycle and the preset target steam pressure value. By controlling the combustion state of the continuous control boiler 20B, the header pressure value is maintained at the target steam pressure value.
More specifically, the second control unit 4B calculates the operation amount (indicated steam amount) for each control cycle based on (Equation 1).
Operation amount (indicated steam amount)
= Deviation proportional output (P control) + Deviation integral output (I control) + Deviation differential output (D control)
(Equation 1)
The second control unit 4B controls the combustion state (combustion rate) of the continuous control boiler 20B included in the second boiler group 2B based on the operation amount (indicated steam amount) calculated for each control cycle.
The second boiler group 2B including the continuous control boiler 20B has been described above.

Next, a first boiler group 2A composed of a step value control boiler 20A whose combustion rate is controlled so that the header pressure value falls within a preset control pressure band, and a target steam pressure value with a preset steam pressure value. In the boiler system 1 including the boiler group 2 consisting of the second boiler group 2B consisting of the continuously controlled boiler 20B whose combustion rate is controlled so as to be, when the total steam load of the boiler system 1 is reduced (that is, the total combustion rate). The header pressure value should be maintained at the target steam pressure value regardless of whether the overall steam load of the boiler system 1 increases (that is, the overall combustion rate increases). The control for enabling the above will be described.

Therefore, the control unit 4 corrects the control pressure band preset in the first control unit 4A according to the overall combustion rate of the second boiler group 2B.
More specifically, when the overall combustion rate of the second boiler group 2B exceeds the preset upper limit combustion rate or exceeds the upper limit combustion rate for the preset first time, the control unit 4 By changing the range of the control pressure band preset in the first control unit 4A, for example, the maximum set pressure value P _max is increased, or the control pressure band is controlled while keeping the _{maximum set pressure value P max as it is.} Narrow the width. As a result, the amount of steam generated in the first boiler group 2A can be increased to reduce the overall combustion rate of the second boiler group 2B, and when the overall steam load of the boiler system 1 increases (that is, the overall combustion rate increases). Even if this is the case), it is possible to maintain the header pressure value at the target steam pressure value.
More specifically, even raising the maximum set pressure value P _max, if not exceeding the upper control limit pressure value as described above, the control width of the control pressure zone as it is, is to increase the maximum set pressure value P _max it can. When the maximum set pressure value P _max has reached the above-mentioned control upper limit pressure value, _{the control width of the control pressure band is narrowed while keeping the maximum set pressure value P max} as it is, that is, at the lower limit value of the control pressure band. A certain minimum set pressure value P _min can be increased. By doing so, the amount of steam generated in the first boiler group 2A can be increased (that is, the overall combustion rate of the first boiler group 2A is increased), and the overall combustion rate of the second boiler group 2B can be decreased.
On the contrary, when the overall combustion rate of the second boiler group 2B is below the preset lower limit combustion rate or the state below the lower limit combustion rate continues for the preset second time, the control unit 4 is set to the first. By changing the range of the control pressure band preset in the control unit 4A, for example, the maximum set pressure value P _max is lowered while keeping the control width of the control pressure band as it is, or the maximum set pressure value P _max is kept as it is. The control width of the control pressure band can be widened. As a result, the amount of steam generated in the first boiler group 2A can be reduced and the overall combustion rate of the second boiler group 2B can be increased. Therefore, when the overall steam load of the boiler system 1 is reduced (that is, overall combustion). Even if the rate drops), the header pressure value can be maintained at the target steam pressure value.

Therefore, as shown in FIG. 2, the control unit 4 controls the combustion amount acquisition unit 41, the upper limit determination unit 42, the lower limit determination unit 43, in addition to the first control unit 4A and the second control unit 4B. A pressure band correction unit 44 is provided. FIG. 2 is a functional block diagram of the control unit 4.
The combustion amount acquisition unit 41 acquires the total combustion rate of the second boiler group 2B.
The upper limit determination unit 42 sets in advance a state in which the overall combustion rate of the second boiler group 2B acquired by the combustion amount acquisition unit 41 exceeds or exceeds the preset upper limit combustion rate. Determine if the time will continue.
The lower limit determination unit 43 sets a state in which the overall combustion rate of the second boiler group 2B acquired by the combustion amount acquisition unit 41 is lower than the preset lower limit combustion rate or lower than the lower limit combustion rate in the preset second time. Determine whether to continue.
The control pressure band correction unit 44 may continue for the first time in which the upper limit determination unit 42 presets a state in which the overall combustion rate of the second boiler group 2B exceeds the upper limit combustion rate or exceeds the upper limit combustion rate. If it is determined, the range of the control pressure band is changed (for example, the control width of the control pressure band is kept as it is and the maximum set pressure value P _max is increased, or the maximum set pressure value P _max is kept as it is and the control of the control pressure band is controlled. By narrowing the width), as described above, the amount of steam generated in the first boiler group 2A is increased (that is, the overall combustion rate of the first boiler group 2A is increased), and the overall combustion of the second boiler group 2B is increased. The rate can be lowered.
On the contrary, when it is determined by the lower limit determination unit 43 that the overall combustion rate of the second boiler group 2B is below the lower limit combustion rate or below the lower limit combustion rate to continue for a preset second time, control is performed. to change the range of pressure zone (e.g., reduce the maximum set pressure value P _max of the control range of the control pressure zone as it is, or the maximum set pressure value P _max as it widen the control range of the control pressure zone) that Then, as described above, it is possible to reduce the amount of steam generated in the first boiler group 2A (that is, lower the overall combustion rate of the first boiler group 2A) and increase the overall combustion rate of the second boiler group 2B. it can.

Next, with reference to FIGS. 3A and 3B, and FIGS. 4A and 4B, a first boiler group 2A composed of two step value control boilers 20A and a second boiler group consisting of two continuous control boilers 20B. When the combustion control according to the first embodiment is carried out while comparing the case where the boiler system 1 including the boiler group 2 including 2B and the boiler group 2 is controlled by the conventional method, the overall steam load of the boiler system 1 is reduced. The header pressure value is targeted regardless of whether the total combustion rate is reduced (that is, the total combustion rate is reduced) or the total steam load of the boiler system 1 is increased (that is, the total combustion rate is increased). The state of making it possible to maintain the steam pressure value will be described.
Here, in FIGS. 3A, 3B, 4A, and 4B, the change in the combustion state of the first boiler group 2A (consisting of two step value control boilers 20A) is shown on the left side of the figure, and the change in the combustion state is shown on the right side of the figure. The change in the combustion state of the second boiler group 2B (consisting of two continuously controlled boilers 20B) is shown. The step value control boiler 20A is a three-position control boiler having a low combustion position L (50% of the maximum combustion amount) and a high combustion position H (combustion rate 100%), and has a maximum steam amount of 2000 kg / h. Further, the continuous control boiler 20B is a continuous control boiler, and each has a maximum steam amount of 2000 kg / h and a minimum combustion state of 20% of the combustion rate.
Here, FIGS. 3A and 3B show a case where the total steam load of the boiler system 1 is reduced (that is, a case where the total combustion rate is reduced) and a case where the boiler system 1 is controlled by combustion by a conventional method, respectively. It is a figure which shows the change of the total combustion rate of the boiler system 1 and the header pressure value at that time when the total steam load of is increased (that is, when the total combustion rate is increased).
On the other hand, FIGS. 4A and 4B show a case where the total steam load of the boiler system 1 is reduced (that is, a case where the total combustion rate is reduced) when the boiler system 1 is burned and controlled by the method according to the first embodiment, respectively. ) And when the total steam load of the boiler system 1 rises (that is, when the total combustion rate rises), it is a figure which shows the change of the total combustion rate of the boiler system 1 and the header pressure value at that time.

First, referring to FIG. 3A, the overall combustion rate of the second boiler group 2B when the overall steam load of the boiler system 1 decreases (that is, when the overall combustion rate decreases) when the combustion is controlled by the conventional method. And the change in the header pressure value at that time will be described. In addition, in FIGS. 3A and 3B, in the first boiler group 2A composed of two step value control boilers 20A of the boiler system 1, the header pressure value has a maximum set pressure value P _max of 0.80 MPa and a control width. In the second boiler group 2B consisting of two continuously controlled boilers 20B, the header pressure value maintains the target steam pressure value of 0.70 MPa, which is proportionally distributed and controlled so as to fall within the control pressure band of 0.20 MPa. It shall be controlled to do so.

First, when the total combustion rate of the boiler system 1 is 50% (generated steam amount 4 t / h), as shown in FIG. 3A (left side), the first boiler group 2A is headed by the first control unit 4A. The pressure value is proportionally distributed and controlled so as to fall within the control pressure band where the maximum set pressure value P _max is 0.80 MPa and the control width is 0.20 MPa, while the second boiler is as shown in FIG. 3A (right side). Group 2B is controlled by the second control unit 4B so that the header pressure value maintains the target steam pressure value of 0.70 MPa. At this time, the amount of steam generated in the first boiler group 2A is 2 t / h (total combustion rate of the first boiler group 2A is 50%), and the amount of steam generated in the second boiler group 2B is 2 t / h (in the second boiler group 2B). The overall combustion rate is 50%).
Next, when the overall combustion rate of the boiler system 1 decreases to 37.5% (generated steam amount 3 t / h) due to the decrease in the overall steam load, as shown in FIG. 3A (left side), the first boiler group 2A The amount of steam generated is 2 t / h (total combustion rate of the first boiler group 2A is 50%), while the amount of steam generated in the second boiler group 2B is 1 t / h (second boiler) as shown in FIG. 3A (right side). The overall combustion rate of group 2B is 25%), and the header pressure value is still maintained at the target steam pressure value of 0.70 MPa by the second control unit 4B.
Further, when the overall combustion rate of the boiler system 1 is reduced to 25% (generated steam amount 2 t / h), as shown in FIG. 3A (right side), all the boilers in the second boiler group 2B are stopped and generated. The amount of steam is 0 t / h (total combustion rate of the second boiler group 2B is 0%), while the amount of steam generated in the first boiler group 2A is 2 t / h (first boiler group 2A) as shown in FIG. 3A (left side). The total combustion rate is 50%).
Further, when the overall combustion rate of the boiler system 1 decreases to 12.5% (generated steam amount 1 t / h), as shown in FIG. 3A (right side), the second boiler group 2B still generates 0 t / h. h (total combustion rate of the second boiler group 2B is 0%), while, as shown in FIG. 3A (left side), the generated steam amount of the first boiler group 2A is 1 t / h (total combustion rate of the first boiler group 2A). 25%), the header pressure value becomes 0.75 PMa, and the header pressure value fluctuates.

Next, referring to FIG. 3B, the total combustion of the second boiler group 2B when the total steam load of the boiler system 1 increases (that is, when the total combustion rate increases) when the combustion is controlled by the conventional method. The rate and the change in the header pressure value at that time will be described.
First, when the total combustion rate of the boiler system 1 is 50% (generated steam amount 4 t / h), the generated steam amount of the first boiler group 2A is 2 t / h (first boiler) as shown in FIG. 3B (left side). Group 2A has an overall combustion rate of 50%), while the amount of steam generated by the second boiler group 2B is 2 t / h (the overall combustion rate of the second boiler group 2B is 50%), as shown in FIG. 3B (right side). The second control unit 4B maintains the header pressure value at the target steam pressure value of 0.70 MPa.
Next, when the overall combustion rate of the boiler system 1 increases to 62.5% (generated steam amount 5 t / h) due to the increase in the overall steam load, as shown in FIG. 3B (left side), the first boiler group. The amount of steam generated in 2A is 2 t / h (total combustion rate of the first boiler group 2A is 50%), while the amount of steam generated in the second boiler group 2B is 3 t / h (third) as shown in FIG. 3B (right side). The overall combustion rate of the 2 boiler group 2B is 75%), and the header pressure value is still maintained at the target steam pressure value of 0.70 MPa by the second control unit 4B.
Further, when the overall combustion rate of the boiler system 1 increases to 75% (generated steam amount 6 t / h), the generated steam amount of the first boiler group 2A is 2 t / h (as shown in FIG. 3B (left side)). The total combustion rate of the first boiler group 2A is 50%), while the amount of steam generated by the second boiler group 2B is 4 t / h (total combustion rate of the second boiler group 2B is 100%) as shown in FIG. 3B (right side). ). Therefore, if the overall combustion rate of the boiler system 1 rises further, the second control unit 4B cannot maintain the target steam pressure value of 0.70 MPa, and is controlled by the first control unit 4A, and the header pressure value becomes higher. It will fluctuate.
For example, when the overall combustion rate of the boiler system 1 increases to 87.5% (generated steam amount 7 t / h), as shown in FIG. 3B (right side), all boilers in the second boiler group 2B are 100%. Even if the amount of steam generated by combustion is 4 t / h (combustion rate 100% of the second boiler group 2B), the target steam pressure value of 0.70 MPa cannot be maintained, while in FIG. 3B (left side). As shown, under the control of the first control unit 4A, the first boiler group 2A has a generated steam amount of 3 t / h (the total combustion rate of the first boiler group 2A is 75%), and the header pressure value is 0.65 PMa. The header pressure value fluctuates.

On the other hand, when the combustion control according to the first embodiment is carried out with reference to FIGS. 4A and 4B, when the overall steam load of the boiler system 1 decreases (that is, when the overall combustion rate decreases). Even if there is, on the contrary, even if the total steam load of the boiler system 1 rises (that is, when the total combustion rate rises), it is possible to maintain the header pressure value at the target steam pressure value. explain. The control upper limit pressure value is set to 0.80 MPa.

First, with reference to FIG. 4A, when combustion is controlled by the method according to the first embodiment, when the overall steam load of the boiler system 1 decreases (that is, when the overall combustion rate decreases), the second boiler group 2B The change between the total combustion rate of the above and the header pressure value at that time will be described.
In FIGS. 4A and 4B, the upper limit combustion rate preset in the second boiler group 2B is 90%, and the lower limit combustion rate is 30%, but the present invention is not limited thereto. The upper limit combustion rate and the lower limit combustion rate can be set as appropriate.

First, when the total combustion rate of the boiler system 1 is 50% (generated steam amount 4 t / h), as shown in FIG. 4A (left side), the first boiler group 2A is headed by the first control unit 4A. The pressure value is proportionally distributed and controlled so as to fall within the control pressure band where the maximum set pressure value P _max is 0.80 MPa and the control width is 0.20 MPa, while the second boiler is as shown in FIG. 4A (right side). Group 2B is controlled by the second control unit 4B so that the header pressure value maintains the target steam pressure value of 0.70 MPa. At this time, the amount of steam generated in the first boiler group 2A is 2 t / h (total combustion rate of the first boiler group 2A is 50%), and the amount of steam generated in the second boiler group 2B is 2 t / h (in the second boiler group 2B). The overall combustion rate is 50%).
Next, due to the decrease in the total steam load, the total combustion rate of the boiler system 1 is reduced to 39.5% (generated steam amount 3.16 t / h), and the total combustion rate of the second boiler group 2B is reduced. When the 29% state (generated steam amount 1.16 t / h) continues for a predetermined time, as shown in FIG. 4A (left side), the control unit 4 sets the maximum set pressure value P _max of the first boiler group 2A to 0. The range of the control pressure band is changed by lowering it by 05 MPa to 0.75 MPa (the control width remains 0.20 MPa).
Then, even when the overall combustion rate of the boiler system 1 is 39.5% (generated steam amount 3.16 t / h), as shown in FIG. 4A (left side), the first boiler group 2A is generated. The amount of steam is 1 t / h (total combustion rate of the first boiler group 2A is 25%), while the amount of steam generated in the second boiler group 2B is 2.16 t / h (second) as shown in FIG. 4A (right side). The overall combustion rate of the boiler group 2B is 54%), and the header pressure value is still maintained at the target steam pressure value of 0.70 MPa by the second control unit 4B.
After that, the overall combustion rate of the boiler system 1 decreased to 27% (generated steam amount 2.16 t / h), and the overall combustion rate of the second boiler group 2B decreased to 29% (generated steam amount 1. When 16 t / h) continues for a predetermined time, as shown in FIG. 4A (left side), the control unit 4 _{further lowers the maximum set pressure value P max} of the first boiler group 2A by 0.05 MPa to 0.70 MPa. The range of the control pressure band is changed (the control width remains 0.20 MPa).
Then, even when the total combustion rate of the boiler system 1 is 27% (generated steam amount 2.16 t / h), as shown in FIG. 4A (left side), the generated steam amount of the first boiler group 2A Is 0 t / h (total combustion rate of the first boiler group 2A is 0%), while the amount of steam generated in the second boiler group 2B is 2.16 t / h (second boiler group) as shown in FIG. 4A (right side). The total combustion rate of 2B is 54%), and the header pressure value is still maintained at the target steam pressure value of 0.70 MPa by the second control unit 4B.
Since the maximum set pressure value P _max of the first boiler group 2A was 0.70 MPa, which is the same as the target steam pressure value of the second boiler group 2B, the overall combustion rate of the boiler system 1 decreased thereafter. On the other hand, the second control unit 4B controls the header pressure value so as to maintain the target steam pressure value of 0.70 MPa.
For example, even when the overall combustion rate of the boiler system 1 is 12.5% (generated steam amount 1 t / h), the header pressure value is still the target steam pressure value of 0.70 MPa by the second control unit 4B. Can be maintained.
In this way, when the combustion is controlled by the method according to the first embodiment, even if the total combustion rate of the boiler system 1 becomes 12.5% (steam amount 1 t / h), the header pressure value is set to the target steam pressure value. It will be possible to maintain.

Next, with reference to FIG. 4B, when combustion is controlled by the method according to the first embodiment, the second boiler group when the overall steam load of the boiler system 1 increases (that is, when the overall combustion rate increases). The change between the total combustion rate of 2B and the header pressure value at that time will be described.
As described above, since the 0.80 MPa to control the upper limit pressure value, after the maximum set pressure value _{P max} of the first boiler group 2A reaches 0.80 MPa, instead increase the maximum set pressure value _{P max} This is dealt with by narrowing the control pressure band.
First, when the total combustion rate of the boiler system 1 is 50% (generated steam amount 4 t / h), the generated steam amount of the first boiler group 2A is 2 t / h (first boiler group) as shown in FIG. 4B (left side). 2A overall combustion rate 50%), on the other hand, as shown in FIG. 4B (right side), the amount of steam generated in the second boiler group 2B is 2 t / h (total combustion rate of the second boiler group 2B 50%). 2 The control unit 4B maintains the header pressure value at the target steam pressure value of 0.70 MPa.
Next, due to the increase in the total steam load, the total combustion rate of the boiler system 1 rises to 70.5% (generated steam amount 5.64 t / h), and the total burn rate of the second boiler group 2B rises. When it continues for a predetermined time in a state of 91% (generated steam amount 3.64 t / h), as shown in FIG. 4B (left side), the control unit 4 sets the maximum set pressure value P _max of the first boiler group 2A to 0. _{The range of the control pressure band is changed by setting the minimum set pressure value P min} , which is the lower limit value of the control pressure band, to 0.68 MPa while keeping 80 MPa (the control width is narrowed to 0.12 MPa).
Then, even when the overall combustion rate of the boiler system 1 is 70.5% (generated steam amount 5.64 t / h), as shown in FIG. 4B (left side), the first boiler group 2A is generated. The amount of steam is 3 t / h (total combustion rate of the first boiler group 2A is 75%), while the amount of steam generated in the second boiler group 2B is 2.64 t / h (second) as shown in FIG. 4B (right side). The overall combustion rate of the boiler group 2B is 66%), and the header pressure value is still maintained at the target steam pressure value of 0.70 MPa by the second control unit 4B.
After that, the overall combustion rate of the boiler system 1 increased to 83% (generated steam amount 6.64 t / h), and the combustion rate of the second boiler group 2B increased to 91% again (generated steam amount 3.). When 64 t / h) is continued for a predetermined time, as shown in FIG. 4B (left side), the control unit 4 _{keeps the maximum set pressure value P max} of the first boiler group 2A at 0.80 MPa and lower limits of the control pressure band. The range of the control pressure band is changed by setting the minimum set pressure value P _min , which is a value, to 0.70 MPa (note that the control width is narrowed to 0.10 MPa).
Then, even when the total combustion rate of the boiler system 1 is 83% (generated steam amount 6.64 t / h), as shown in FIG. 4B (left side), the generated steam amount of the first boiler group 2A Is 4 t / h (total combustion rate of the first boiler group 2A is 100%), while the amount of steam generated in the second boiler group 2B is 2.64 t / h (second boiler group) as shown in FIG. 4B (right side). The total combustion rate of 2B is 66%), and the header pressure value is still maintained at the target steam pressure value of 0.70 MPa by the second control unit 4B.
_{The minimum set pressure value P min} , which is the lower limit of the control pressure band of the first boiler group 2A, became 0.70 MPa, which is the same as the target steam pressure value of the second boiler group 2B, due to the correction by the control unit 4. After that, the header pressure value is controlled to maintain the target steam pressure value of 0.70 MPa by the second control unit 4B with respect to the increase in the overall combustion rate of the boiler system 1.
For example, even when the overall combustion rate of the boiler system 1 is 87.5% (generated steam amount 7 t / h), the header pressure value is still the target steam pressure value of 0.70 MPa by the second control unit 4B. Can be maintained.
In this way, when the combustion is controlled by the method according to the first embodiment, even if the total combustion rate of the boiler system 1 becomes 87.5% (generated steam amount 7 t / h), the header pressure value is set as the target steam pressure value. Can be maintained at. More specifically, when the combustion is controlled by the method according to the first embodiment, the header pressure value is set as the target steam pressure even when the overall combustion rate of the boiler system 1 is 100% (generated steam amount 8 t / h). It is possible to maintain the value.

As described above, according to the first embodiment, the second control unit 4B can secure a wide band of the overall combustion rate of the second boiler group 2B capable of maintaining the header pressure value at the target steam pressure value. It will be possible. As a result, it is possible to secure the followability to the load fluctuation and the stability of the header pressure.
In the description of the first embodiment, when the maximum set pressure value P _max is less than or equal to 0.80 MPa, the control unit 4 keeps the control width of the control pressure band in the first control unit 4a at 0.20 MPa. The control pressure band is changed by raising or lowering the maximum set pressure value P _{max , and when the maximum set pressure value P max} is 0.80 MPa, which is the control upper limit pressure value, the control range is narrowed, but the control range is not limited to this. .. For example, when the maximum set pressure value P _max is less than 0.80 MPa and the maximum set pressure value P _max is increased by changing the control pressure band, the minimum set pressure value P _min which is the lower limit value of the control pressure band is left as it is. , The maximum set pressure value P _max may be increased. Further, if lowering the minimum set pressure value P _min is the lower limit value of the control pressure zone by changing a control pressure zone, as it is the maximum set pressure value P _max, the minimum set pressure value P which is the lower limit of the control pressure zone You may _{try to lower min.}

<Second Embodiment>
The case where the control pressure band set in advance in the first control unit 4A is corrected according to the overall combustion rate of the second boiler group 2B has been described above. On the other hand, instead of correcting the control pressure band, a plurality of control patterns corresponding to the total load of the first boiler group 2A are provided in advance, and the first one is provided according to the total combustion rate of the second boiler group 2B. An embodiment (hereinafter, referred to as “second embodiment”) for changing the control pattern of the boiler group 2A may be applied.

The second embodiment will be described. The second embodiment will be mainly described with reference to points different from those of the first embodiment, and detailed description of the same configuration as that of the first embodiment will be omitted. In the second embodiment, the description of the first embodiment is appropriately applied to the points not particularly described. Further, also in the second embodiment, the same effect as in the first embodiment is achieved.

In the boiler system 1 according to the second embodiment, the control unit 4 has a preset state in which the overall combustion rate of the second boiler group 2B exceeds or exceeds the preset upper limit combustion rate. When continuing for 1 hour, the amount of steam generated in the first boiler group 2A is increased by changing the control pattern of the first boiler group 2A, and the overall combustion rate of the second boiler group 2B is lowered. On the contrary, when the overall combustion rate of the second boiler group 2B is below the preset lower limit combustion rate or the state of being below the lower limit combustion rate continues for the second hour, the control unit 4 controls the control pattern of the first boiler group 2A. By changing the above, the amount of steam generated in the first boiler group 2A is reduced, and the overall combustion rate of the second boiler group 2B is increased.

When the control pressure band is applied as the control pattern of the first boiler group 2A and five patterns are provided, for example, pattern 1 (maximum set pressure value = 0.80 MPa, control width = 0.10 MPa), pattern 2 (maximum setting). Pressure value = 0.80 MPa, control width = 0.12 MPa), pattern 3 (maximum set pressure value = 0.80 MPa, control width = 0.20 MPa), pattern 4 (maximum set pressure value = 0.75 MPa, control width = The control pressure band may be shifted as in 0.20 MPa) and pattern 5 (maximum set pressure value = 0.70 MPa, control width = 0.20 MPa).
When the header pressure value is maintained at the target steam pressure value of 0.70 MPa by the second control unit 4B, the overall combustion rate of the first boiler group 2A is 100% combustion in pattern 1, 75% combustion in pattern 2, and pattern. 3 is 50% burned, pattern 4 is 25% burned, and pattern 5 is 0% burned.
The control pattern described above is an example and is not limited thereto. The plurality of pieces may be 2 or more. Further, when the control pressure band is applied as the control pattern, the maximum set pressure value and the control width may be classified differently.

Therefore, as shown in FIG. 5, the control unit 4 controls the combustion amount acquisition unit 41, the upper limit determination unit 42, the lower limit determination unit 43, in addition to the first control unit 4A and the second control unit 4B. A pressure band designation unit 45 is provided. FIG. 5 is a functional block diagram of the control unit 4. The control pressure band designation unit 45 corresponds to the “control pressure band correction unit” according to claim 3.
When the control pressure band designation unit 45 determines by the upper limit determination unit 42 that the overall combustion rate of the second boiler group 2B exceeds the upper limit combustion rate or exceeds the upper limit combustion rate for the first hour. , The entire first boiler group 2A is replaced with the control pressure band associated with the control pattern number instructed by the control pressure band designation unit 45 via the signal line 16C for the first control unit 4A. Specify to switch to the control pressure band associated with the control pattern number on the side where the combustion rate increases.
When the control pattern number is specified by the control unit 4 (control pressure band designation unit 45), the first control unit 4A sets the header pressure value within the range of the control pressure band associated with the designated control pattern number. The combustion state of the first boiler group 2A is controlled so as to fit in.

For example, in the above example, the control pressure band designation unit 45 is instructing the first control unit 4A to control pattern 3 (the overall combustion rate of the first boiler group 2A is 50% combustion), and the first is When it is determined that the state in which the overall combustion rate of the 2 boiler group 2B exceeds the upper limit combustion rate or the state in which the upper limit combustion rate is equal to or higher than the upper limit combustion rate continues for the first hour, the control pressure band designation unit 45 is sent to the first control unit 4A. On the other hand, it is specified to switch to the control pattern 2 (the total combustion rate of the first boiler group 2A is 75% combustion) via the signal line 16C.
On the contrary, the control pressure band designation unit 45 instructs the first control unit 4A to perform the control pattern 3 (the total combustion rate of the first boiler group 2A is 50% combustion), and the second boiler group 2B When it is determined that the state in which the total combustion rate of the above is below the preset lower limit combustion rate or the state in which the state is below the lower limit combustion rate continues for the second time, the control pressure band designation unit 45 sends the first control unit 4A to the first control unit 4A. It is specified to switch to the control pattern 4 (the total combustion rate of the first boiler group 2A is 25% combustion) via the signal line 16C.

When the combustion control according to the second embodiment is carried out with reference to FIGS. 6A and 6B, the reverse is true even when the overall steam load of the boiler system 1 is reduced (that is, when the overall combustion rate is reduced). The state in which the header pressure value can be maintained at the target steam pressure value will be described even when the overall steam load of the boiler system 1 increases (that is, when the overall combustion rate increases). The control upper limit pressure value is set to 0.80 MPa.

First, with reference to FIG. 6A, when combustion is controlled by the method according to the second embodiment, the second boiler group 2B when the overall steam load of the boiler system 1 decreases (that is, when the overall combustion rate decreases). The change between the total combustion rate of the above and the header pressure value at that time will be described.
In FIGS. 6A and 6B, the upper limit combustion rate preset in the second boiler group 2B is 90% and the lower limit combustion rate is 30% as in the first embodiment, but the present invention is limited thereto. It's not something. The upper limit combustion rate and the lower limit combustion rate can be set as appropriate.

First, when the overall combustion rate of the boiler system 1 is 50% (generated steam amount 4 t / h), as shown in FIG. 6A (left side), the first boiler group 2A is in a state where the control pattern 3 is instructed. The header pressure value is proportionally distributed and controlled by the first control unit 4A so as to fall within the control pressure band where the maximum set pressure value P _max is 0.80 MPa and the control width is 0.20 MPa, while FIG. 6A ( As shown on the right side), the second boiler group 2B is controlled by the second control unit 4B so that the header pressure value maintains the target steam pressure value of 0.70 MPa. At this time, the amount of steam generated in the first boiler group 2A is 2 t / h (total combustion rate of the first boiler group 2A is 50%), and the amount of steam generated in the second boiler group 2B is 2 t / h (in the second boiler group 2B). The overall combustion rate is 50%).
Next, due to the decrease in the total steam load, the total combustion rate of the boiler system 1 is reduced to 39.5% (generated steam amount 3.16 t / h), and the total combustion rate of the second boiler group 2B is reduced. When the 29% state (generated steam amount 1.16 t / h) continues for a predetermined time, as shown in FIG. 6A (left side), the control unit 4 controls the control pressure band of the first boiler group 2A with the control pattern 4 (maximum). The set pressure value = 0.75 MPa, control width = 0.20 MPa).
Then, even when the overall combustion rate of the boiler system 1 is 39.5% (generated steam amount 3.16 t / h), as shown in FIG. 6A (left side), the first boiler group 2A is generated. The amount of steam is 1 t / h (total combustion rate of the first boiler group 2A is 25%), while the amount of steam generated in the second boiler group 2B is 2.16 t / h (second) as shown in FIG. 6A (right side). The overall combustion rate of the boiler group 2B is 54%), and the header pressure value is still maintained at the target steam pressure value of 0.70 MPa by the second control unit 4B.
After that, the overall combustion rate of the boiler system 1 decreased to 27% (generated steam amount 2.16 t / h), and the overall combustion rate of the second boiler group 2B decreased to 29% (generated steam amount 1. When 16 t / h) continues for a predetermined time, as shown in FIG. 6A (left side), the control unit 4 controls the control pressure band of the first boiler group 2A with the control pattern 5 (maximum set pressure value = 0.70 MPa, control width). = 0.20 MPa).
Then, even when the total combustion rate of the boiler system 1 is 27% (generated steam amount 2.16 t / h), as shown in FIG. 6A (left side), the generated steam amount of the first boiler group 2A Is 0 t / h (total combustion rate of the first boiler group 2A is 0%), while the amount of steam generated in the second boiler group 2B is 2.16 t / h (second boiler group) as shown in FIG. 6A (right side). The total combustion rate of 2B is 54%), and the header pressure value is still maintained at the target steam pressure value of 0.70 MPa by the second control unit 4B.
Since the maximum set pressure value P _max of the first boiler group 2A was 0.70 MPa, which is the same as the target steam pressure value of the second boiler group 2B, the overall combustion rate of the boiler system 1 decreased thereafter. On the other hand, the second control unit 4B controls the header pressure value so as to maintain the target steam pressure value of 0.70 MPa.
For example, even when the overall combustion rate of the boiler system 1 is 12.5% (generated steam amount 1 t / h), the header pressure value is still the target steam pressure value of 0.70 MPa by the second control unit 4B. Can be maintained.
In this way, when the combustion is controlled by the method according to the second embodiment, even if the total combustion rate of the boiler system 1 becomes 12.5% (steam amount 1 t / h), the header pressure value is set to the target steam pressure value. It will be possible to maintain.

Next, with reference to FIG. 6B, when combustion is controlled by the method according to the second embodiment, the second boiler group when the overall steam load of the boiler system 1 increases (that is, when the overall combustion rate increases). The change between the total combustion rate of 2B and the header pressure value at that time will be described.
First, when the total combustion rate of the boiler system 1 is 50% (generated steam amount 4 t / h), as shown in FIG. 6B (left side), the first boiler group 2A is in a state where the control pattern 3 is instructed. The amount of steam generated in the 1-boiler group 2A is 2 t / h (total combustion rate of the 1st boiler group 2A is 50%), while the amount of steam generated in the 2nd boiler group 2B is 2 t / h / as shown in FIG. 6B (right side). It becomes h (the total combustion rate of the second boiler group 2B is 50%), and the header pressure value maintains the target steam pressure value of 0.70 MPa by the second control unit 4B.
Next, due to the increase in the overall steam load, the overall combustion rate of the boiler system 1 increases to 70.5% (generated steam amount 5.64 t / h), and the overall combustion rate of the second boiler group 2B increases. When it continues for a predetermined time in a state of 91% (generated steam amount 3.64 t / h), as shown in FIG. 6B (left side), the control unit 4 controls the control pressure band of the first boiler group 2A with the control pattern 2 (maximum). Change to the set pressure value = 0.80 MPa, control width = 0.12 MPa).
Then, even when the overall combustion rate of the boiler system 1 is 70.5% (generated steam amount 5.64 t / h), as shown in FIG. 6B (left side), the first boiler group 2A is generated. The amount of steam is 3 t / h (total combustion rate of the first boiler group 2A is 75%), while the amount of steam generated in the second boiler group 2B is 2.64 t / h (second) as shown in FIG. 6B (right side). The overall combustion rate of the boiler group 2B is 66%), and the header pressure value is still maintained at the target steam pressure value of 0.70 MPa by the second control unit 4B.
After that, the overall combustion rate of the boiler system 1 increased to 83% (generated steam amount 6.64 t / h), and the combustion rate of the second boiler group 2B increased to 91% again (generated steam amount 3.). When 64 t / h) is continued for a predetermined time, as shown in FIG. 6B (left side), the control unit 4 sets the control pressure band of the first boiler group 2A to the control pattern 1 (maximum set pressure value = 0.80 MPa, control width). = 0.10 MPa).
Then, even when the total combustion rate of the boiler system 1 is 83% (generated steam amount 6.64 t / h), as shown in FIG. 6B (left side), the generated steam amount of the first boiler group 2A Is 4 t / h (total combustion rate of the first boiler group 2A is 100%), while the amount of steam generated in the second boiler group 2B is 2.64 t / h (second boiler group) as shown in FIG. 6B (right side). The total combustion rate of 2B is 66%), and the header pressure value is still maintained at the target steam pressure value of 0.70 MPa by the second control unit 4B.
_{The minimum set pressure value P min} , which is the lower limit of the control pressure band of the first boiler group 2A, became 0.70 MPa, which is the same as the target steam pressure value of the second boiler group 2B, due to the correction by the control unit 4. After that, the header pressure value is controlled to maintain the target steam pressure value of 0.70 MPa by the second control unit 4B with respect to the increase in the overall combustion rate of the boiler system 1.
For example, even when the overall combustion rate of the boiler system 1 is 87.5% (generated steam amount 7 t / h), the header pressure value is still the target steam pressure value of 0.70 MPa by the second control unit 4B. Can be maintained.
In this way, when the combustion is controlled by the method according to the second embodiment, even if the total combustion rate of the boiler system 1 becomes 87.5% (generated steam amount 7 t / h), the header pressure value is set as the target steam pressure value. Can be maintained at. More specifically, when the combustion is controlled by the method according to the second embodiment, the header pressure value is set as the target steam pressure even when the overall combustion rate of the boiler system 1 is 100% (generated steam amount 8 t / h). It is possible to maintain the value.

As described above, according to the second embodiment, the second control unit 4B can secure a wide band of the overall combustion rate of the second boiler group 2B capable of maintaining the header pressure value at the target steam pressure value. It will be possible. As a result, it is possible to secure the followability to the load fluctuation and the stability of the header pressure.

<Third Embodiment>
The case where the control pressure band set in advance in the first control unit 4A is corrected according to the overall combustion rate of the second boiler group 2B has been described above. On the other hand, instead of correcting the control pressure band, the control pressure band is fixed to one, and the maximum combustion control target of the first control unit 4A is set according to the overall combustion rate of the second boiler group 2B. An embodiment in which the number of virtual boilers is changed (hereinafter, referred to as “third embodiment”) may be applied.

The third embodiment will be described. The third embodiment will be mainly described with reference to points different from those of the first embodiment, and detailed description of the same configuration as that of the first embodiment will be omitted. In the third embodiment, the description of the first embodiment is appropriately applied to the points not particularly described. Further, also in the third embodiment, the same effect as in the first embodiment is achieved.

In the boiler system 1 according to the third embodiment, the control unit 4 has a preset state in which the overall combustion rate of the second boiler group 2B exceeds or exceeds the preset upper limit combustion rate. When continuing for 1 hour, the amount of steam generated in the 1st boiler group 2A is increased by increasing the maximum number of virtual boilers to be combustion controlled included in the 1st boiler group 2A, and the entire 2nd boiler group 2B is increased. Reduce the combustion rate. On the contrary, when the overall combustion rate of the second boiler group 2B is below the preset lower limit combustion rate or the state of being below the lower limit combustion rate continues for the second hour, it becomes the combustion control target included in the first boiler group 2A. By reducing the maximum number of virtual boilers, the amount of steam generated in the first boiler group 2A is reduced, and the overall combustion rate of the second boiler group 2B is increased.
The control pressure band in the third embodiment _{is fixed at a maximum set pressure value P max} of 0.85 MPa, a minimum set pressure value P _min of 0.65 MPa, and a control width of 0.20 MPa.

Therefore, as shown in FIG. 7, in addition to the first control unit 4A and the second control unit 4B, the control unit 4 includes a combustion amount acquisition unit 41, an upper limit determination unit 42, a lower limit determination unit 43, and virtual. A boiler number correction unit 46 is provided. FIG. 7 is a functional block diagram of the control unit 4.
When the virtual boiler number correction unit 46 determines by the upper limit determination unit 42 that the overall combustion rate of the second boiler group 2B exceeds the upper limit combustion rate or exceeds the upper limit combustion rate for the first hour. , The maximum number of virtual boilers subject to combustion control included in the first boiler group 2A is increased, and the lower limit determination unit 43 determines that the overall combustion rate of the second boiler group 2B is below the lower limit combustion rate or below the lower limit combustion rate. When it is determined that the state continues for the second time, the maximum number of virtual boilers subject to combustion control included in the first boiler group 2A is reduced.

When the maximum number of virtual boilers is specified by the control unit 4 (virtual boiler number correction unit 46), the first control unit 4A first controls the header pressure value so as to fall within the preset control pressure band. Combustion control included in the boiler group 2A The combustion state of the virtual boiler included in the maximum number of virtual boilers to be controlled is controlled.

Next, with reference to FIGS. 8A and 8B, a boiler group consisting of a first boiler group 2A composed of two step value control boilers 20A and a second boiler group 2B consisting of two continuous control boilers 20B. Even if the total steam load of the boiler system 1 is reduced (that is, the total combustion rate is reduced) when the combustion control according to the third embodiment is performed on the boiler system 1 including 2. It will be described how the header pressure value can be maintained at the target steam pressure value even when the total steam load of the system 1 increases (that is, when the total combustion rate increases).
Here, in FIGS. 8A and 8B, the change in the combustion state of the first boiler group 2A (consisting of two step value control boilers 20A) is shown on the left side of the figure, and the change in the combustion state of the first boiler group 2A (consisting of two continuous control boilers) is shown on the right side of the figure. The change in the combustion state of the second boiler group 2B (consisting of 20B) is shown. The step value control boiler 20A is a three-position control boiler having a low combustion position L (50% of the maximum combustion amount) and a high combustion position H (combustion rate 100%), and has a maximum steam amount of 2000 kg / h. Further, the continuous control boiler 20B is a continuous control boiler, and each has a maximum steam amount of 2000 kg / h and a minimum combustion state of 20% of the combustion rate.
8A and 8B show a case where the total steam load of the boiler system 1 is reduced (that is, a case where the total combustion rate is reduced) and a case where the boiler system 1 is controlled by combustion according to the method according to the third embodiment, respectively. It is a figure which shows the change of the total combustion rate of the 2nd boiler group 2B, and the header pressure value at that time, when the total steam load of is increased (that is, when the total combustion rate is increased).

First, with reference to FIG. 8A, when combustion is controlled by the method according to the third embodiment, when the overall steam load of the boiler system 1 decreases (that is, when the overall combustion rate decreases), the second boiler group 2B The change between the total combustion rate of the above and the header pressure value at that time will be described. In the control pressure band preset in the first control unit 4A, the maximum set pressure value P _max is 0.85 MPa and the control width is 0.20 MPa.
First, when the total combustion rate of the boiler system 1 is 50% (generated steam amount 4 t / h), the maximum number of virtual boilers subject to combustion control in the first boiler group 2A is low, as shown in FIG. 8A (left side). Two combustion virtual boilers (L boilers) and one high combustion virtual boiler (H boiler) are set. In the first boiler group 2A, the header pressure value is set to the maximum set pressure value P by the first control unit 4A. _{Proportional distribution control is performed so that the max} is 0.85 MPa and the control width is 0.20 MPa within the control pressure band. On the other hand, as shown in FIG. 8A (right side), the second boiler group 2B is the second control unit 4B. Therefore, the header pressure value is controlled to maintain the target steam pressure value of 0.70 MPa. At this time, in the first boiler group 2A, the amount of steam generated by the combustion of the two L boilers is 2 t / h (the total combustion rate of the first boiler group 2A is 50%), and the amount of steam generated in the second boiler group 2B is It becomes 2t / h (the total combustion rate of the second boiler group 2B is 50%).
Next, due to the decrease in the overall steam load, the overall combustion rate of the boiler system 1 decreased to 39.5% (generated steam amount 3.16 t / h), and as shown in FIG. 8A (right side), the second boiler When the overall combustion rate of group 2B decreases and the state of 29% (generated steam amount 1.16 t / h) is continued for a predetermined time, the control unit 4 causes the maximum number of virtual boilers to be controlled by combustion of the first boiler group 2A. Is changed to two L boilers.
Then, even when the overall combustion rate of the boiler system 1 is 39.5% (generated steam amount 3.16 t / h), as shown in FIG. 8A (left side), the first boiler group 2A is The amount of steam generated by the combustion of one L boiler is 1 t / h (25% of the total combustion rate of the first boiler group 2A), while the generated steam of the second boiler group 2B as shown in FIG. 8A (right side). The amount is 2.16 t / h (total combustion rate of the second boiler group 2B is 54%), and the header pressure value is still maintained at the target steam pressure value of 0.70 MPa by the second control unit 4B.
After that, the overall combustion rate of the boiler system 1 decreased to 27% (generated steam amount 2.16 t / h), and the overall combustion rate of the second boiler group 2B decreased to 29% (generated steam amount 1. When 16t / h) is continued for a predetermined time, the control unit 4 changes the maximum number of virtual boilers subject to combustion control to one L boiler.
Then, even when the total combustion rate of the boiler system 1 is 27% (generated steam amount 2.16 t / h), as shown in FIG. 8A (left side), the generated steam amount of the first boiler group 2A Is 0 t / h (total combustion rate of the first boiler group 2A is 0%), while the amount of steam generated in the second boiler group 2B is 2.16 t / h (second boiler group) as shown in FIG. 8A (right side). The total combustion rate of 2B is 54%), and the header pressure value is still maintained at the target steam pressure value of 0.70 MPa by the second control unit 4B.
Since the amount of steam generated in the first boiler group 2A became 0 t / h, the header pressure value was subsequently increased by the second control unit 4B in response to the decrease in the overall combustion rate of the boiler system 1. Is controlled to maintain the target steam pressure value of 0.70 MPa.
For example, even when the total combustion rate of the boiler system 1 is 12.5% (generated steam amount 1 t / h), as shown in FIG. 8A (left side), the generated steam amount of the first boiler group 2A Is 0 t / h (total combustion rate of the first boiler group 2A is 0%), while the amount of steam generated by the second boiler group 2B is 1 t / h (of the second boiler group 2B) as shown in FIG. 8A (right side). The total combustion rate is 25%), and the header pressure value can still be maintained at the target steam pressure value of 0.70 MPa by the second control unit 4B.
In this way, when combustion is controlled by the method according to the third embodiment, even if the overall combustion rate of the boiler system 1 becomes 12.5% (generated steam amount 1 t / h), the header pressure value is set as the target steam pressure value. Can be maintained at.

Next, with reference to FIG. 8B, when combustion is controlled by the method according to the third embodiment, the second boiler group when the overall steam load of the boiler system 1 increases (that is, when the overall combustion rate increases). The change between the total combustion rate of 2B and the header pressure value at that time will be described.
First, when the total combustion rate of the boiler system 1 is 50% (generated steam amount 4 t / h), as shown in FIG. 8B (left side), the maximum number of virtual boilers subject to combustion control in the first boiler group 2A is L. Two boilers and one H boiler are set, and in the first boiler group 2A, the _{header pressure value is 0.85 MPa for the maximum set pressure value P max} and 0.20 MPa for the control width by the first control unit 4A. The second boiler group 2B is controlled by the second control unit 4B so that the header pressure value maintains the target steam pressure value of 0.70 MPa. At this time, as shown in FIG. 8B (left side), in the first boiler group 2A, the amount of steam generated by the combustion of two L boilers was 2 t / h (the total combustion rate of the first boiler group 2A was 50%). On the other hand, as shown in FIG. 8B (right side), the amount of steam generated in the second boiler group 2B is 2 t / h (the total combustion rate of the second boiler group 2B is 50%).
Next, due to the increase in the total steam load, the total combustion rate of the boiler system 1 rises to 70.5% (generated steam amount 5.64 t / h), and the burn rate of the second boiler group 2B rises to 91. When the% state (generated steam amount 3.64 t / h) is continued for a predetermined time, as shown in FIG. 8B (left side), the control unit 4 determines the maximum number of virtual boilers to be combustion controlled in the first boiler group 2A. Change to 2 L boilers and 2 H boilers.
Then, even when the overall combustion rate of the boiler system 1 is 70.5% (generated steam amount 5.64 t / h), as shown in FIG. 8B (left side), the first boiler group 2A Due to the combustion of two L boilers and one H boiler, the amount of steam generated was 3 t / h (75% of the total combustion rate of the first boiler group 2A), while the second one was shown in FIG. 8B (right side). The amount of steam generated in the boiler group 2B is 2.64 t / h (the overall combustion rate of the second boiler group 2B is 66%), and the header pressure value is still maintained at the target steam pressure value of 0.70 MPa by the second control unit 4B. ..
After that, the control unit 4 is controlled by the second control unit 4B so that the header pressure value maintains the target steam pressure value of 0.70 MPa with respect to the increase in the overall combustion rate of the boiler system 1. To.
For example, when the total combustion rate of the boiler system 1 is 87.5% (generated steam amount 7 t / h), the generated steam amount of the first boiler group 2A is 4 t / h (first) as shown in FIG. 8B (left side). 1 Boiler group 2A overall combustion rate 100%) On the other hand, as shown in FIG. 8B (right side), the amount of steam generated in the second boiler group 2B is 3 t / h (total combustion rate 75% in the second boiler group 2B). Therefore, the header pressure value can still maintain the target steam pressure value of 0.70 MPa.
The third embodiment in which the maximum number of virtual boilers to be burned and controlled by the first control unit 4A is changed according to the overall combustion rate of the second boiler group 2B has been described above.
As described above, according to the third embodiment, the second control unit 4B can secure a wide band of the overall combustion rate of the second boiler group 2B capable of maintaining the header pressure value at the target steam pressure value. It will be possible. As a result, it is possible to secure the followability to the load fluctuation and the stability of the header pressure.
In the third embodiment, the maximum number of combustions to be controlled may be applied instead of the maximum number of virtual boilers to be controlled for combustion. The maximum number of combustion units refers to the maximum number of boilers to be controlled by the first control unit 4A.

As described above, in the description of the first embodiment, the second embodiment, and the third embodiment, the boiler system in which the first boiler group 2A is two three-position control boilers and the second boiler group 2B is two continuous control boilers. Although 1 is exemplified, the present invention is not limited to this. As the first boiler group 2A, each stage value control boiler 20A may be an arbitrary N position control boiler (N ≧ 2), and an arbitrary number of such stage value control boilers 20A may be included. Further, as the second boiler group 2B, each continuous control boiler 20B may output an arbitrary maximum amount of generated steam, and an arbitrary number of such continuous control boilers 20B may be included.
Further, in the first embodiment, the set value and the correction value of the control pressure band of the first boiler group 2A of the boiler system 1 and the correction value thereof, and the target steam pressure value in the second boiler group 2B have been illustrated, but these values are also exemplified. It can be set as appropriate. Similarly, in the second embodiment, a plurality of control patterns in the control pressure band of the first boiler group 2A and a target steam pressure value in the second boiler group 2B have been illustrated, but these values can also be set as appropriate. ..
Similarly, in the third embodiment, the set value of the control pressure band of the first boiler group 2A of the boiler system 1, the correction value based on the number of virtual boilers, and the target steam pressure value in the second boiler group 2B have been illustrated. The value of can also be set as appropriate.

Although the preferred embodiment of the boiler system 1 of the present invention has been described above, the present invention is not limited to the above-described embodiment and can be appropriately modified.

<Modification example 1: Upper limit generated steam amount and lower limit generated steam amount>
In the first embodiment, the second embodiment, and the third embodiment, the overall combustion rate of the second boiler group 2B is applied as an index value of the combustion amount of the second boiler group 2B, and the upper limit combustion rate and the lower limit combustion rate are applied. Was preset. Along with this, the combustion amount acquisition unit 41 acquires the overall combustion rate of the second boiler group 2B, and the upper limit determination unit 42 is in a state where the overall combustion rate of the second boiler group 2B exceeds the upper limit combustion rate or is equal to or higher than the upper limit combustion rate. It is determined whether or not the state continues for the first hour, and the lower limit determination unit 43 determines whether the state in which the overall combustion rate of the second boiler group 2B is below the lower limit combustion rate or below the lower limit combustion rate continues for the second hour. It was judged whether or not.
On the other hand, as an index value of the combustion amount of the second boiler group 2B, the total combustion amount (total generated steam amount) of the second boiler group 2B is applied instead of the total combustion rate of the second boiler group 2B. The upper limit combustion amount (upper limit generated steam amount) and the lower limit combustion amount (lower limit generated steam amount) may be set in advance.
By doing so, the control pressure band correction unit 44 is in a state where the total combustion amount (total generated steam amount) of the second boiler group 2B exceeds the upper limit combustion amount (upper limit generated steam amount) or the upper limit combustion by the upper limit determination unit 42. When it is determined that the state of exceeding the amount (upper limit generated steam amount) continues for the preset first time, the maximum set pressure value P _max is increased by changing the range of the control pressure band. May be good. On the contrary, the lower limit determination unit 43 causes the total combustion amount (total generated steam amount) of the second boiler group 2B to be lower than the lower limit combustion amount (lower limit generated steam amount) or lower than the lower limit combustion amount (lower limit generated steam amount). When it is determined that the value continues for the preset second time, the minimum set pressure value P _min , which is the lower limit value of the control pressure band, may be lowered by changing the range of the control pressure band.
Similarly, in the control pressure band designation unit 45, the upper limit determination unit 42 indicates that the total combustion amount (total generated steam amount) of the second boiler group 2B exceeds the upper limit combustion amount (upper limit generated steam amount) or the upper limit combustion amount (upper limit combustion amount). When it is determined that the state of exceeding the upper limit generated steam amount) continues for the preset first time, the generated steam amount of the first boiler group 2A is increased by changing the control pattern of the first boiler group 2A. The overall combustion rate of the second boiler group 2B may be lowered. On the contrary, the lower limit determination unit 43 causes the total combustion amount (total generated steam amount) of the second boiler group 2B to be lower than the lower limit combustion amount (lower limit generated steam amount) or lower than the lower limit combustion amount (lower limit generated steam amount). When it is determined that is continued for the preset second time, the control unit 4 reduces the amount of steam generated in the first boiler group 2A by changing the control pattern of the first boiler group 2A. The overall combustion rate of the second boiler group 2B may be increased.
Similarly, the virtual boiler number correction unit 46 is in a state where the total combustion amount (total generated steam amount) of the second boiler group 2B exceeds the upper limit combustion amount (upper limit generated steam amount) or the upper limit combustion amount (upper limit generated steam amount) by the upper limit determination unit 42. When it is determined that the state of exceeding the upper limit generated steam amount) continues for the first hour, the number of virtual boilers subject to combustion control included in the first boiler group 2A is increased, and the lower limit determination unit 43 determines the second. It was determined that the state in which the total combustion amount (total generated steam amount) of the boiler group 2B is below the lower limit combustion amount (lower limit generated steam amount) or below the lower limit combustion amount (lower limit generated steam amount) continues for the second hour. In this case, the number of virtual boilers subject to combustion control included in the first boiler group 2A may be reduced.
By doing so, the same effects as those of the first embodiment, the third embodiment, and the modifications shown below can be obtained.
As an index value of the combustion amount of the second boiler group 2B, a value other than the total combustion rate and the total combustion amount (generated steam amount) may be applied.

<Modification 2: Upper limit combustion rate and lower limit combustion rate>
In the description of the first embodiment, the second embodiment, and the third embodiment, the upper limit combustion rate is 90% and the lower limit combustion rate is 30%, but the upper limit combustion rate and the lower limit combustion rate are set to the second boiler group. The boiler efficiency of the boiler 20B included in 2B may be included in the range of the eco-driving zone in which the boiler efficiency is higher than a predetermined threshold value.
By doing so, the second control unit 4B can set the band of the total combustion rate of the second boiler group 2B, which can maintain the header pressure value to the target steam pressure value, within the range of the eco-driving zone. Combustion efficiency can be increased.

<Modification 3: Change by 2nd control unit 4B>
In the first embodiment, the control unit 4 includes a first control unit 4A, a second control unit 4B, a combustion amount acquisition unit 41, an upper limit determination unit 42, a lower limit determination unit 43, and a control pressure band correction unit 44. In the second embodiment, the control unit 4 includes the first control unit 4A, the second control unit 4B, the combustion amount acquisition unit 41, the upper limit determination unit 42, and the lower limit determination unit. 43 and a control pressure band designation unit 45 are provided, and in the third embodiment, the control unit 4 includes a first control unit 4A, a second control unit 4B, a combustion amount acquisition unit 41, and the like. Although it is configured to include an upper limit determination unit 42, a lower limit determination unit 43, and a virtual boiler number correction unit 46, the configuration is not limited to this.
For example, as shown in FIG. 9, a number control device 3A having a first control unit 4A for controlling the first boiler group 2A and a number control device 3B having a second control unit 4B for controlling the second boiler group 2B. , And the second control unit 4B may include a combustion amount acquisition unit 41, an upper limit determination unit 42, a lower limit determination unit 43, and a control pressure band correction unit 44.
Similarly, as shown in FIG. 10, the number control device 3A having the first control unit 4A for controlling the first boiler group 2A and the number control device 3B having the second control unit 4B for controlling the second boiler group 2B. The second control unit 4B may include a combustion amount acquisition unit 41, an upper limit determination unit 42, a lower limit determination unit 43, and a control pressure band designation unit 45.
Similarly, as shown in FIG. 11, the number control device 3A having the first control unit 4A for controlling the first boiler group 2A and the number control device 3B having the second control unit 4B for controlling the second boiler group 2B. The second control unit 4B may include a combustion amount acquisition unit 41, an upper limit determination unit 42, a lower limit determination unit 43, and a virtual boiler number correction unit 46.
At that time, for example, the number control device 3A and the number control device 3B may be electrically connected via a signal line.
By doing so, as in the first embodiment, the second embodiment, and the third embodiment, the header pressure value can be maintained at the target steam pressure value, and the overall combustion rate of the second boiler group 2B can be maintained. It is possible to secure a wide band. As a result, it is possible to secure the followability to the load fluctuation and the stability of the header pressure.
Although not shown, in FIG. 9, the first control unit 4A may include a combustion amount acquisition unit 41, an upper limit determination unit 42, a lower limit determination unit 43, and a control pressure band correction unit 44. .. Similarly, in FIG. 10, the first control unit 4A may include a combustion amount acquisition unit 41, an upper limit determination unit 42, a lower limit determination unit 43, and a control pressure band designation unit 45. Similarly, in FIG. 11, the first control unit 4A may include a combustion amount acquisition unit 41, an upper limit determination unit 42, a lower limit determination unit 43, and a virtual boiler number correction unit 46.

<Modification example 4: Control device>
In the third modification (modification of the first embodiment), the number of control devices 3A having the first control unit 4A for controlling the first boiler group 2A and the number of units having the second control unit 4B for controlling the second boiler group 2B. A control device 3B is provided, and a second control unit 4B (or a first control unit 4A) includes a combustion amount acquisition unit 41, an upper limit determination unit 42, a lower limit determination unit 43, and a control pressure band correction unit 44. It is configured to be provided, but is not limited to this configuration.
For example, as shown in FIG. 12, the control device 6 is provided, and the control device 6 includes a combustion amount acquisition unit 41, an upper limit determination unit 42, a lower limit determination unit 43, and a control pressure band correction unit 44. May be good. More specifically, the control device 6 is electrically connected to the number control device 3A (first control unit 4A) and the number control device 3B (second control unit 4B) via, for example, a signal line 17. It may be.
Similarly, in the modification 3 (modification of the second embodiment), the number control device 3A having the first control unit 4A for controlling the first boiler group 2A and the second control unit 4B for controlling the second boiler group 2B. The second control unit 4B (or the first control unit 4A) includes a combustion amount acquisition unit 41, an upper limit determination unit 42, a lower limit determination unit 43, and a control pressure band designation unit 45. However, the configuration is not limited to this configuration.
For example, as shown in FIG. 13, the control device 6 is provided, and the control device 6 includes a combustion amount acquisition unit 41, an upper limit determination unit 42, a lower limit determination unit 43, and a control pressure band designation unit 45. May be good. More specifically, the control device 6 is electrically connected to the number control device 3A (first control unit 4A) and the number control device 3B (second control unit 4B) via, for example, a signal line 17. It may be.
Similarly, in the modification 3 (modification of the third embodiment), the number control device 3A having the first control unit 4A for controlling the first boiler group 2A and the second control unit 4B for controlling the second boiler group 2B. The second control unit 4B (or the first control unit 4A) includes a combustion amount acquisition unit 41, an upper limit determination unit 42, a lower limit determination unit 43, and a virtual boiler number correction unit 46. However, the configuration is not limited to this configuration.
For example, as shown in FIG. 14, the control device 6 is provided, and the control device 6 includes a combustion amount acquisition unit 41, an upper limit determination unit 42, a lower limit determination unit 43, and a virtual boiler number correction unit 46. May be good. More specifically, the control device 6 is electrically connected to the number control device 3A (first control unit 4A) and the number control device 3B (second control unit 4B) via, for example, a signal line 17. It may be.
By doing so, as in the first embodiment, the second embodiment, and the third embodiment, the header pressure value can be maintained at the target steam pressure value, and the overall combustion rate of the second boiler group 2B can be maintained. It is possible to secure a wide band. As a result, it is possible to secure the followability to the load fluctuation and the stability of the header pressure.

<Modification example 5: Step value control boiler>
In the present embodiment, the step value control boiler 20A is a three-position control boiler, but the present invention is not limited to this. That is, the step value control boiler 20A of the present invention may be applied to each N position control boiler (N is an arbitrary two or more integers). The boiler capacity, the number of stages N at the combustion position, the combustion rate at each combustion position, and the like may be different for each stage value control boiler 20A. Further, the number of step value control boilers 20A may be any number of 1 or more.

<Modification example 6: Continuous control boiler>
In the present embodiment, the continuous control boiler 20B has the same boiler capacity, but the present invention is not limited to this. That is, the continuous control boiler 20B can be applied even when the number of the continuous control boilers 20B is an arbitrary number of 1 or more and the combustion capacity as the minimum combustion amount, the unit steam amount, and the maximum combustion amount is different for each continuous control boiler.
Further, in the present embodiment, the second boiler group 2B composed of the continuous control boiler 20B is feedback-controlled by PID control, but the present invention is not limited to PID control. Feedback control by PI control may be used.

<Modification 7>
In the present embodiment, a boiler group composed of a step value control boiler is applied as the first boiler group, but the boiler group is not limited to the step value control boiler. Any boiler group that controls the combustion rate of each boiler based on the control pressure band determined by the maximum set pressure value P _{max and the control width may be used.}
Similarly, a boiler group consisting of continuously controlled boilers was applied as the second boiler group, but the boiler group is not limited to the continuously controlled boilers. Any group of boilers that controls the combustion rate of each boiler so that the vapor pressure reaches the set target vapor pressure may be used.

<Modification 8>
Further, as the boiler in the present embodiment, it may be applied to a boiler device having various structures such as a small once-through type steam boiler device and a furnace tube smoke tube boiler.

1 Boiler system 2 Boiler group 2A 1st boiler group 2B 2nd boiler group 20 Boiler 20A Step value control boiler 20B Continuous control boiler 2A 1st boiler group 2B 2nd boiler group 3, 3A, 3B Number control device 4 Control unit 4A 1st 1 Control unit 4B 2nd control unit 41 Combustion amount acquisition unit 42 Upper limit judgment unit 43 Lower limit judgment unit 44 Control pressure band correction unit 45 Control pressure band specification unit 46 Virtual boiler number correction unit

Claims (6)

A boiler group consisting of a first boiler group consisting of one or more boilers and a second boiler group consisting of one or more boilers not belonging to the first boiler group,
A steam header that collects the steam generated in the boiler group,
A vapor pressure measuring means for measuring the vapor pressure inside the steam header, and
A control unit that controls the combustion state of the boiler group,
It is a boiler system equipped with
The control unit
The measured vapor pressure value, which is the vapor pressure value measured by the vapor pressure measuring means, falls within the range of the control pressure band defined by the preset control width with the preset maximum set pressure value as the upper limit value. As described above, the first control unit that controls the combustion state of the first boiler group and
A second control unit that controls the combustion state of the second boiler group so as to keep the steam pressure value measured by the steam pressure measuring means at a set target steam pressure value.
A combustion amount acquisition unit that acquires the overall combustion rate of the second boiler group, and
Whether or not the state in which the total combustion rate of the second boiler group acquired by the combustion amount acquisition unit exceeds the preset upper limit combustion rate or the state in which the upper limit combustion rate is equal to or higher continues for the preset first time. Upper limit judgment unit for judgment and
Whether or not the state in which the overall combustion rate of the second boiler group acquired by the combustion amount acquisition unit is below the preset lower limit combustion rate or the state in which it is below the lower limit combustion rate continues for the preset second time. Lower limit judgment unit for judgment and
When it is determined by the upper limit determination unit that the state in which the overall combustion rate of the second boiler group exceeds the upper limit combustion rate or the state in which the upper limit combustion rate is equal to or higher than the upper limit combustion rate continues for the first hour, the control pressure band By changing the range, the overall combustion rate of the first boiler group is increased, and the overall combustion rate of the second boiler group is below the lower limit combustion rate or below the lower limit combustion rate by the lower limit determination unit. Is determined to continue for the second time, the boiler system includes a control pressure band correction unit that lowers the overall combustion rate of the first boiler group by changing the range of the control pressure band. .. A control upper limit pressure value, which is an upper limit value of the maximum set pressure value, is preset in the maximum set pressure value.
The control pressure band correction unit
When the upper limit determination unit determines that the overall combustion rate of the second boiler group exceeds the upper limit combustion rate or exceeds the upper limit combustion rate for the first hour.
When the maximum set pressure value exceeds the control upper limit pressure value, the control width of the control pressure band is narrowed while keeping the maximum set pressure value as it is.
If the control upper limit pressure value is not exceeded even if the maximum set pressure value is increased, the control width of the control pressure band is kept as it is, and the maximum set pressure value is increased so as not to exceed the control upper limit pressure value.
When it is determined by the lower limit determination unit that the state in which the overall combustion rate of the second boiler group is below the lower limit combustion rate or below the lower limit combustion rate continues for the second time.
The boiler system according to claim 1, wherein the control width of the control pressure band is widened while keeping the maximum set pressure value as it is, or the control width of the control pressure band is kept as it is and the maximum set pressure value is lowered. The first control unit
Each of the plurality of preset maximum set pressure values is set as the upper limit value, and each has a plurality of control pressure bands defined by a preset control width, and any one of the plurality of control pressure bands. By setting one control pressure band, the measured vapor pressure value, which is the vapor pressure value measured by the vapor pressure measuring means, is the control pressure band of any one of the plurality of set control pressure bands. The combustion state of the first boiler group is controlled so as to be within the range.
The control pressure band correction unit
When it is determined by the upper limit determination unit that the state in which the overall combustion rate of the second boiler group exceeds the upper limit combustion rate or the state in which the upper limit combustion rate is equal to or higher than the upper limit combustion rate continues for the first hour, the setting is made. Instead of the control pressure band of any one of the plurality of control pressure bands, another control pressure band of the plurality of control pressure bands is set so as to increase the combustion rate of the first boiler group. ,
When the lower limit determination unit determines that the overall combustion rate of the second boiler group is below the lower limit combustion rate or below the lower limit combustion rate continues for the second time, the setting is made. Instead of the control pressure band of any one of the plurality of control pressure bands, another control pressure band of the plurality of control pressure bands is set so as to reduce the combustion rate of the first boiler group. , The boiler system according to claim 1. A boiler group consisting of a first boiler group consisting of one or more boilers capable of burning at a plurality of stepwise combustion positions, and a second boiler group consisting of one or more boilers not belonging to the first boiler group. ,
A steam header that collects the steam generated in the boiler group,
A vapor pressure measuring means for measuring the vapor pressure inside the steam header, and
A control unit that controls the combustion state of the boiler group,
It is a boiler system equipped with
Any boiler belonging to the first group of boilers is regarded as a set of virtual boilers in which the difference steam amount between the amount of steam at an arbitrary combustion position and the amount of steam at a combustion position one level below it is virtualized as a boiler.
The control unit
The measured vapor pressure value, which is the vapor pressure value measured by the vapor pressure measuring means, falls within the range of the control pressure band defined by the preset control width with the preset maximum set pressure value as the upper limit value. As described above, the first control unit that controls the combustion state of the first boiler group and
A second control unit that controls the combustion state of the second boiler group so as to keep the steam pressure value measured by the steam pressure measuring means at a set target steam pressure value.
A combustion amount acquisition unit that acquires the overall combustion rate of the second boiler group, and
Whether or not the state in which the total combustion rate of the second boiler group acquired by the combustion amount acquisition unit exceeds the preset upper limit combustion rate or the state in which the upper limit combustion rate is equal to or higher continues for the preset first time. Upper limit judgment unit for judgment and
Whether or not the state in which the overall combustion rate of the second boiler group acquired by the combustion amount acquisition unit is below the preset lower limit combustion rate or the state in which it is below the lower limit combustion rate continues for the preset second time. Lower limit judgment unit for judgment and
When the upper limit determining unit determines that the overall combustion rate of the second boiler group exceeds the upper limit combustion rate or exceeds the upper limit combustion rate for the first hour, the first boiler group The state in which the total number of virtual boilers subject to combustion control included in the above is increased and the overall combustion rate of the second boiler group is below the lower limit combustion rate or below the lower limit combustion rate by the lower limit determination unit is the first. A boiler system including a virtual boiler number correction unit that reduces the maximum number of virtual boilers subject to combustion control included in the first boiler group when it is determined to continue for two hours. A boiler group consisting of a first boiler group consisting of one or more boilers and a second boiler group consisting of one or more boilers not belonging to the first boiler group,
A steam header that collects the steam generated in the boiler group,
A vapor pressure measuring means for measuring the vapor pressure inside the steam header, and
Each of the plurality of preset maximum set pressure values is set as the upper limit value, and each has a plurality of control pressure bands defined by a preset control width, and any one of the plurality of control pressure bands. By setting one control pressure band, the measured vapor pressure value, which is the vapor pressure value measured by the vapor pressure measuring means, is the control pressure band of any one of the plurality of set control pressure bands. A first control unit that controls the combustion state of the first boiler group so as to be within the range, and
A second control unit that controls the combustion state of the second boiler group so as to keep the steam pressure value measured by the steam pressure measuring means at a set target steam pressure value.
It is a boiler system equipped with
The second control unit
A combustion amount acquisition unit that acquires the overall combustion rate of the second boiler group, and
Whether or not the state in which the total combustion rate of the second boiler group acquired by the combustion amount acquisition unit exceeds the preset upper limit combustion rate or the state in which the upper limit combustion rate is equal to or higher continues for the preset first time. Upper limit judgment unit for judgment and
Whether or not the state in which the overall combustion rate of the second boiler group acquired by the combustion amount acquisition unit is below the preset lower limit combustion rate or the state in which it is below the lower limit combustion rate continues for the preset second time. Lower limit judgment unit for judgment and
When the upper limit determination unit determines that the state in which the overall combustion rate of the second boiler group exceeds the upper limit combustion rate or exceeds the upper limit combustion rate continues for the first hour, the first control unit On the other hand, in place of any one of the set control pressure bands, another of the plurality of control pressure bands is used so as to increase the combustion rate of the first boiler group. Instructed to set one control pressure band of
When the lower limit determination unit determines that the state in which the overall combustion rate of the second boiler group is below the lower limit combustion rate or below the lower limit combustion rate continues for the second time, the first control unit. On the other hand, in order to reduce the combustion rate of the first boiler group in place of any one of the set control pressure bands, another of the plurality of control pressure bands is used. A boiler system comprising a control pressure band compensator, which directs the setting of one control pressure band. The upper limit combustion rate and the lower limit combustion rate are any one of claims 1 to 5, which are included in the range of the eco-driving zone in which the boiler efficiency of the boilers included in the second boiler group is higher than a predetermined threshold value. Boiler system described in section.

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