JP2016176679A - Boiler system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boiler system capable of performing number control in which priorities that a stepped value control boiler and a continuous control boiler respectively have are utilized.SOLUTION: The present invention relates to a boiler system 1 comprising a boiler group 2 in which a step value control boiler 20A and a continuous control boiler 20B are mixedly included. A number controller 3 which performs number control over the boiler group 2 comprises: an output control part 41 which controls a combustion state of the boiler group 2 so as to output steam from the continuous control boiler 20B by a request steam amount corresponding to a request load; and an output switching part 42 which switches output of a steam amount corresponding to a combustion position from the continuous control boiler 20B to the step value control boiler 20A on condition that an amount of steam output from the continuous control boiler 20B reaches a predetermined steam amount set to a value smaller than the value obtained by subtracting the product of a maximum variation steam amount and a preset first time from the sum of a steam amount corresponding to the combustion position and an increased reference steam amount.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a boiler system having a boiler group in which a step value control boiler and a continuous control boiler are mixed.

  There has been proposed a boiler system including a boiler group having a plurality of boilers that can be burned by changing the combustion rate, and a number control device that controls the combustion state of the boiler group according to a required load. In such a boiler system, a steam header that stores steam generated from a plurality of boilers is provided, and steam is supplied from the steam header to a load device.

Conventionally, as such a boiler system, a step value control boiler capable of burning by changing the combustion rate stepwise has been widely used, but in recent years, continuous control capable of burning by changing the combustion rate continuously. Boiler systems using boilers are also beginning to spread.
The stage value control boiler is an N-position boiler that burns at a plurality of stages of combustion positions (for example, a three-position boiler that stops combustion, low combustion, high combustion, etc.). The rate is changed stepwise (eg every 50%). On the other hand, the continuous control boiler refers to a boiler whose combustion rate can be changed in increments of 1%, for example, which can be finely adjusted as compared with a step value control boiler, and pressure stability is improved.

Here, in the boiler system configured by the step value control boiler, the unit control device sets the combustion pattern of each boiler in advance and burns each boiler with the combustion pattern corresponding to the steam pressure of the steam header. The combustion state of the boiler group is controlled (see Patent Document 1).
Further, in a boiler system composed of continuous control boilers, the unit control device sets a target pressure in advance, and calculates a control amount corresponding to the deviation between the steam pressure in the steam header and the target pressure, thereby obtaining the boiler. The combustion state of the group is controlled (see Patent Document 2).

JP 2013-072609 A JP 2010-048662 A

  The combustion control methods described in Patent Documents 1 and 2 assume a state in which the boiler group is composed of only the step value control boiler or only the continuous control boiler, and the step value control boiler and the continuous control boiler. It was not supposed to be applied to the boiler group where

  Accordingly, an object of the present invention is to provide a boiler system capable of controlling the number of units utilizing the advantages of each boiler in a boiler system in which a step value control boiler and a continuous control boiler are mixed.

  The present invention includes a stage value control boiler capable of burning at a plurality of staged combustion positions, a boiler group including a plurality of continuous control boilers capable of burning by continuously changing a combustion rate, and the boiler according to a required load. And a control unit that controls a combustion state of the group, wherein the plurality of continuous control boilers are configured to cause a maximum fluctuating steam amount that is an upper limit value of a steam amount that can fluctuate per unit time, and to burn A can increase reference steam amount serving as a reference for increasing the number of the continuous control boilers is set, and the control unit outputs the steam for the required steam amount corresponding to the required load from the continuous control boiler. The output control unit for controlling the combustion state of the boiler group, and the amount of steam output from the continuous control boiler reaches a predetermined amount of steam that exceeds the amount of steam corresponding to the combustion position combustible in the step value control boiler. An output switching unit that switches the output of the steam amount corresponding to the combustion position from the continuous control boiler to the step value control boiler, on the condition that the predetermined steam amount corresponds to the steam corresponding to the combustion position. The present invention relates to a boiler system that is set to a value smaller than a value obtained by subtracting a product of the maximum fluctuation steam amount and a preset first time from the sum of the amount and the reference steam amount for the can.

  The continuous control boiler is set with a minimum combustion steam amount that is a steam amount in a minimum combustion state of the continuous control boiler, and the predetermined steam amount includes a steam amount corresponding to the combustion position and the minimum steam amount. It may be greater than or equal to the sum of the combustion steam amount.

  In addition, the first time may be a time equal to or longer than an activation suppression time until a can increase instruction can be issued after issuing a combustion instruction to one continuous control boiler.

  The present invention includes a stage value control boiler capable of burning at a plurality of staged combustion positions, a boiler group including a continuous control boiler capable of burning by continuously changing a combustion rate, and the boiler group according to a required load. A continuous control boiler for controlling the combustion state, wherein the continuous control boiler includes a maximum variable steam amount that is an upper limit value of a steam amount that can vary per unit time, and the continuous control boiler that performs combustion. Is set as a reference for reducing the number of boilers, and the control unit is configured to burn the boiler group so as to output steam for the required steam amount corresponding to the required load from the continuous control boiler. An output control unit for controlling the state, and a steam amount output from the continuous control boiler reaches a predetermined steam amount exceeding a steam amount corresponding to a combustion position capable of being combusted in the step value control boiler. An output switching unit that switches the output of the steam amount corresponding to the combustion position from the continuous control boiler to the step value control boiler, and the predetermined steam amount is the steam amount corresponding to the combustion position, and The present invention relates to a boiler system that is larger than the sum of a reduced-can reference steam amount and a steam amount obtained by integrating a second time set in advance to the maximum fluctuation steam amount.

  Further, the second time may be a time longer than a suppression time until a can-decreasing instruction is made after issuing a combustion instruction to one continuous control boiler.

  According to the present invention, while the continuous control boiler is used for load follow-up, the step value control boiler is used for base combustion, so that it is possible to control the number of units taking advantage of the advantages of both boilers.

It is a figure showing the outline of the boiler system of this embodiment of the present invention. It is a figure which shows the outline of the boiler group of the said embodiment. It is a figure which shows the boiler characteristic of the step value control boiler which comprises a boiler group, and a continuous control boiler. It is a block diagram which shows the function structure of the control part of a number control apparatus. It is a figure which shows the operation example in the case of switching the output of the amount of steam between a step value control boiler and a continuous control boiler. It is a figure which shows the operation example in the case of switching the output of the amount of steam between a step value control boiler and a continuous control boiler. It is a figure which shows the operation example in the case of switching the output of the amount of steam between a step value control boiler and a continuous control boiler. It is a figure which shows the operation example in the case of switching the output of the amount of steam between a step value control boiler and a continuous control boiler. It is a figure which shows the operation example in the case of switching the output of the amount of steam between a step value control boiler and a continuous control boiler. It is a figure which shows the operation example in the case of switching the output of the amount of steam between a step value control boiler and a continuous control boiler. It is a figure which shows the operation example in the case of switching the output of the amount of steam between a step value control boiler and a continuous control boiler. It is a figure which shows the operation example in the case of switching the output of the amount of steam between a step value control boiler and a continuous control boiler.

Hereinafter, preferred embodiments of the boiler system of the present invention will be described with reference to the drawings.
First, the overall configuration of the boiler system 1 according to the present embodiment will be described with reference to FIG. The boiler system 1 includes a boiler group 2 in which a step value control boiler 20A and a continuous control boiler 20B are mixed, a steam header 6 that collects steam generated in the plurality of boilers 20A and 20B, and an inside of the steam header 6 A vapor pressure sensor 7 for measuring pressure and a number control device 3 having a control unit 4 for controlling the combustion state of the boiler group 2 are provided.

  As shown in FIG. 1, the boilers 20 </ b> A and 20 </ b> B respectively include boiler bodies 21 </ b> A and 21 </ b> B in which combustion is performed and local control units 22 </ b> A and 22 </ b> B that control the combustion state of the boilers 20 </ b> A and 20 </ b> B.

  The local control units 22A and 22B change the combustion state of the boilers 20A and 20B according to the steam consumption. Specifically, the local control units 22 </ b> A and 22 </ b> B control the combustion states of the boilers 20 </ b> A and 20 </ b> B based on a control signal transmitted from the number control device 3 via the signal line 16. Further, the local control units 22A and 22B transmit signals used in the number control device 3 to the number control means via the signal line 16. Examples of signals used in the number control device 3 include actual combustion states of the boilers 20A and 20B, other data, and the like.

The boiler group 2 generates steam to be supplied to the steam use facility 18.
The steam header 6 is connected to a plurality of boilers 20 </ b> A and 20 </ b> B constituting the boiler group 2 via a steam pipe 11. A downstream side of the steam header 6 is connected to a steam use facility 18 via a steam pipe 12.
The steam header 6 collects and stores the steam generated in the boiler group 2, thereby adjusting the mutual pressure difference and pressure fluctuation of the boilers 20A and 20B, and using the steam whose pressure is adjusted as steam using equipment. 18 is supplied.

  The vapor pressure sensor 7 is electrically connected to the number control device 3 via the signal line 13. The vapor pressure sensor 7 measures the vapor pressure inside the vapor header 6 (the pressure of the vapor generated in the boiler group 2) (hereinafter also referred to as “header pressure”), and a signal related to the measured vapor pressure (vapor pressure signal) ) Is transmitted to the number control device 3 through the signal line 13.

  The number control device 3 is electrically connected to the plurality of boilers 20 </ b> A and 20 </ b> B via the signal line 16. This number control device 3 controls the combustion state of each of the boilers 20A and 20B based on the steam pressure value inside the steam header 6 (hereinafter also referred to as “header pressure value”) measured by the steam pressure sensor 7. .

The above boiler system 1 can supply the steam generated in the boiler group 2 to the steam using equipment 18 via the steam header 6.
The load required in the boiler system 1 (required load) is the amount of steam consumed in the steam using facility 18. The number control device 3 calculates the fluctuation of the header pressure that occurs in response to the fluctuation of the steam consumption based on the header pressure value (physical quantity) measured by the steam pressure sensor 7, and each boiler constituting the boiler group 2. The combustion state of 20A and 20B is controlled.

  Specifically, if the steam consumption increases due to an increase in demand for the steam use facility 18 and the output steam amount supplied to the steam header 6 is insufficient, the header pressure value decreases. On the other hand, if the steam consumption decreases due to a decrease in demand for the steam use facility 18 and the output steam amount supplied to the steam header 6 becomes excessive, the header pressure value increases. The number control device 3 monitors the fluctuation of the steam consumption based on the fluctuation of the header pressure value. And the number control apparatus 3 controls the combustion amount of each boiler 20A and 20B so that the vapor | steam for the target steam amount computed based on the header pressure value may be produced | generated.

Here, with reference to FIG. 2, the boiler group 2 which comprises the boiler system 1 of this embodiment is demonstrated. FIG. 2 is a diagram showing an outline of the boiler group 2 according to the present embodiment.
The boiler group 2 of the present embodiment includes three step value control boilers 20A and two continuous control boilers 20B, and the three step value control boilers 20A constitute a step value control boiler group 2A. The continuous control boiler of the stand constitutes a continuous control boiler group 2B.

(Description of step value control boiler 20A)
The step value control boiler 20A is configured to control the combustion amount by selectively turning on / off the combustion or adjusting the size of the flame, etc., and the combustion amount is stepwise according to the selected combustion position. It is a boiler that can be increased or decreased.

In the stage value control boiler 20A of the present embodiment, the combustion amount at each combustion position and the combustion capacity as the maximum combustion amount (combustion amount at the high combustion position) are set equal in each of the stage value control boilers 20A. The combustion state (combustion position, combustion rate) can be controlled in stages, and is a so-called four-position controlled boiler.
1) Combustion stop position (first combustion position: 0%)
2) Low combustion position L (second combustion position: set at 5 to 35% of the maximum combustion amount, for example, 20% in this embodiment)
3) Medium combustion position M (third combustion position: set at 40 to 70% of the maximum combustion amount, for example, 45% in this embodiment)
4) High combustion position H (fourth combustion position: 100% (maximum combustion amount)).

  As the stage value control boiler 20A of the stage value control boiler group 2A, in addition to the 4-position control, the combustion amount is the combustion stop position (first combustion position), the low combustion position L (second combustion position), and the high combustion position. So-called three-position control, which is controllable to three combustion positions of H (third combustion position), or five or more positions may be used. Further, the boiler capacity of each stage value control boiler 20A, the number of stages of the combustion position, and the like may be different for each stage value control boiler 20A.

Priorities are set for the respective boilers 20A of the stage value control boiler group 2A. The priority order for the stage value control boiler 20A can be arbitrarily set. In this embodiment, the priority order is set for each combustion position of the stage value control boiler 20A. Specifically, as shown in FIG. 2B, the first priority is set at the low combustion position L of the No. 1 boiler, and the second priority is set at the middle combustion position M of the No. 1 boiler. . In addition, the third priority rank sets not the high combustion position H of the No. 1 boiler but the low combustion position L of the No. 2 boiler. Note that the priority order setting shown in FIG. 2B is merely an example.
The number-of-units control device 3 (control unit 4) burns in order from the higher-priority step value control boiler 20A (combustion position), and stops combustion in order from the lower-priority step value control boiler 20A (combustion position). .

Next, boiler characteristics (efficiency characteristics) of the step value control boiler 20A will be described. FIG. 3 is a diagram showing boiler characteristics of the step value control boiler 20A and the continuous control boiler 20B constituting the boiler group 2. As shown in FIG.
The stage value control boiler 20A burns at a plurality of staged combustion positions, and the boiler efficiency (thermal efficiency of the stage value control boiler 20A) differs at each combustion position. As shown in FIG. 3, in the stage value control boiler 20 </ b> A of the present embodiment, the combustion position (eco-combustion position) with the highest combustion efficiency among the plurality of combustion positions is set to the middle combustion position M. .

(Description of continuous control boiler 20B)
With the continuous control boiler 20B, the combustion amount can be continuously controlled 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 boiler. The continuous control boiler 20B adjusts the amount of combustion by controlling the opening degree (combustion ratio) of a valve for supplying fuel to the burner and a valve for supplying combustion air, for example.

  Further, the continuous control of the combustion amount means that the calculation and signal in the local control unit 22B are digitally handled in stages (for example, the output (combustion amount) of the continuous control boiler 20B is in increments of 1%). Even when the output is controlled).

In the present embodiment, the change of the combustion state between the combustion stop state S0 and the minimum combustion state S1 of the continuous control boiler 20B is controlled by turning on / off the combustion of the continuous control boiler 20B (burner). In the range from the minimum combustion state S1 to the maximum combustion state S2, the combustion amount can be controlled continuously.
More specifically, a unit steam amount U, which is a unit of variable steam amount, is set in each of the plurality of continuous control boilers 20B. Thereby, the continuous control boiler 20B can change a steam | vapor amount per unit steam | vapor amount U unit in the range of 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 continuous control boiler 20B, but from the viewpoint of improving the followability of the output steam amount to the required steam amount in the boiler system 1. The maximum steam amount of the continuous control boiler 20B is preferably set to 0.1% to 20%, and more preferably set to 1% to 10%.

  Furthermore, an upper limit value of the amount of steam that can fluctuate per unit time (hereinafter referred to as “maximum fluctuating steam amount”) is set in each of the plurality of continuous control boilers 20B. The maximum fluctuating steam amount is an integral multiple of the unit steam amount U.

  Further, as shown in FIG. 2B, priorities are set for the plurality of continuous control boilers 20B belonging to the continuous control boiler group 2B. In the present embodiment, when the steam consumption increases, the combustion rate is increased in order from the continuous control boiler 20B having the highest priority, and when the steam consumption decreases, the continuous control boiler with the lower priority. It is assumed that the combustion rate is decreased sequentially from 20B.

Further, a plurality of continuous control boilers 20B belonging to the continuous control boiler group 2B is set with a can increase reference steam amount serving as a reference for increasing the number of continuous control boilers to be burned.
For example, when one of the boilers 20B belonging to the continuous control boiler group 2B is first burned with one boiler 20B having a high priority, when the steam consumption increases, the combustion rate of the boiler 20B is increased. However, when the output steam amount of the boiler 20B exceeds the canister reference steam amount set in the boiler 20B, the boiler 20B having the next highest priority is burned to cope with the increase in steam consumption.

Similarly, each of the plurality of continuous control boilers 20B belonging to the continuous control boiler group 2B is set with a can reduction reference steam amount serving as a reference for reducing the number of continuous control boilers to be burned.
For example, when a plurality of boilers 20B belonging to the continuous control boiler group 2B are burning, if the steam consumption is reduced, the combustion rate of the boiler 20B having a lower priority is reduced, but the output steam amount of the boiler 20B is reduced. When the boiler reduction standard steam amount set in the boiler 20B is below, the combustion of the boiler 20B is stopped (standby) to cope with the reduction in steam consumption.

Next, the boiler characteristics (efficiency characteristics) of the continuous control boiler 20B will be described with reference to FIG.
The continuous control boiler 20B can continuously change the combustion rate in the range from the minimum combustion state S1 to the maximum combustion state S2, but the boiler efficiency (thermal efficiency of the continuous control boiler 20B) differs depending on the combustion rate. Therefore, the combustion rate at which the boiler efficiency is highest (for example, 98%) is set as an eco-operation point, and the range of the combustion rate at which the boiler efficiency is higher than a predetermined value (for example, 97%) is set as the eco-operation zone. Set. Referring to FIG. 3, the eco-operation point of the continuous control boiler 20B is a combustion rate of 50%, and the eco-operation zone is in the range of a combustion rate of 30% to 70%.

  The boiler capacity of each continuous control boiler 20B, the combustion rate of the minimum combustion state S1, the unit steam amount U, the maximum fluctuating steam amount, the increased reference steam amount, the reduced reference steam amount, the eco operation point, the eco operation zone, etc. Each continuous control boiler 20B may be different.

  Next, the configuration of the number control device 3 will be described in detail. The number control device 3 includes a control unit 4 and a storage unit 5 as shown in FIG.

  The control unit 4 transmits various instructions to the step value control boiler 20A and the continuous control boiler 20B via the signal line 16, or receives various data from each boiler 20A or 20B, and the step value control boiler. Control of the combustion state and the number of operating units of 20A and continuous control boiler 20B is executed. When each boiler 20A or 20B receives the signal of the change instruction of the combustion state from the number control device 3, it controls the combustion amount of the corresponding boiler 20A or 20B according to the instruction. The detailed configuration of the control unit 4 will be described later.

The memory | storage part 5 memorize | stores the information regarding the instruction | indication transmitted to each boiler 20A or 20B, the information regarding the combustion state received from each boiler 20A or 20B, the information regarding the priority of each boiler group 2A or 2B, etc.
Further, information regarding the boiler capacity of each stage value control boiler 20A, the number of stages of the combustion position, the eco-combustion position described later, and the like can be stored.
Similarly, the boiler capacity of each continuous control boiler 20B, the combustion rate in the minimum combustion state S1, the unit steam amount U, the maximum fluctuating steam amount, the increased reference steam amount, the reduced reference steam amount, the eco operation point, the eco operation zone, etc. Information about the device can be stored.

  Next, the configuration of the control unit 4 will be described in more detail. In this embodiment, according to the request | requirement of the steam usage equipment 18, the continuous control boiler 20B is burned first. When the amount of steam output from the continuous control boiler 20B becomes the amount of steam that can be output in the step value control boiler 20A, the step value control boiler 20A is combusted, and the output of the steam amount is changed from the continuous control boiler 20B to the step value. Switch to the control boiler 20A. In order to realize such control, as shown in FIG. 4, the control unit 4 includes an output control unit 41 and an output switching unit 42.

  The output control unit 41 controls the combustion state of the boiler group 2 so that steam corresponding to the required steam amount corresponding to the required load is output from the continuous control boiler 20B. That is, the output control unit 41 causes the steam amount output from the boiler group 2 to follow the required steam amount by continuously controlling the combustion rate of the continuous control boiler 20B.

The output switching unit 42 is under the condition that the amount of steam output from the continuous control boiler 20B under the control of the output control unit 41 reaches a predetermined amount of steam that exceeds the amount of steam corresponding to the combustion position combustible in the step value control boiler 20A. In addition, the output of the steam amount corresponding to the combustion position is switched from the continuous control boiler 20B to the step value control boiler 20A.
Although details will be described later, the output switching unit 42 switches the output of the steam amount from the continuous control boiler 20B to the step value control boiler 20A in accordance with the priority set in the step value control boiler 20A. As an example, when all of the stage value control boilers 20A have stopped combustion, the low combustion position L of the No. 1 boiler with the highest priority is the highest priority. Therefore, the output switching unit 42 continuously outputs the steam amount on condition that the steam amount output from the continuous control boiler 20B reaches a predetermined steam amount exceeding the steam amount corresponding to the low combustion position L of the No. 1 boiler. The control boiler 20B is switched to the low combustion position L of the No. 1 boiler.

It should be noted that the predetermined steam amount that is switched by the output switching unit 42 can be arbitrarily set. In this respect, in the present embodiment, the predetermined steam amount is set from the viewpoint of stability of the boiler system 1 or efficient combustion of the continuous control boiler 20B.
That is, when the amount of steam output from the continuous control boiler 20B is switched to the step value control boiler 20A, the amount of steam output from the continuous control boiler 20B decreases, and the combustion rate of the continuous control boiler 20B decreases. On the premise of the reduction in the combustion rate, the predetermined steam amount is set from the above viewpoint.

A case where the predetermined steam amount is set in consideration of the stability of the boiler system 1 will be described.
As described above, even if it is the continuous control boiler 20B, the combustion stop state S0 to the minimum combustion state S1 are performed step by step on / off. Therefore, when the combustion rate decreased by switching is lower than the minimum combustion state S1, the combustion of the continuous control boiler 20B is stopped, and the continuous control boiler 20B is repeatedly started and stopped depending on the subsequent load fluctuation.
Therefore, a steam amount that is larger by the minimum steam amount output in the minimum combustion state S1 of the continuous control boiler 20B than the steam amount corresponding to the combustible combustion position in the step value control boiler 20A is set as the predetermined steam amount. Thereby, even if the combustion rate of continuous control boiler 20B falls by switching of output switching part 42, the combustion rate of continuous control boiler 20B falls only to the minimum combustion state S1, and continuous control boiler 20B Combustion never stops.

(Rapid increase in steam consumption after switching)
In the combustion control of the continuous control boiler group 2B, when a combustion instruction is issued to one continuous control boiler 20B in the continuous control boiler group 2B, until a predetermined activation suppression time (for example, 3 seconds) elapses, A steaming instruction for starting steaming cannot be given to the boiler 20B in the combustion stopped state.
For this reason, after reducing the combustion rate of the continuous control boiler 20B by switching the output switching unit 42, for example, in response to a rapid increase in steam consumption, the continuous control boiler 20B has a first time (for example, When the combustion is instructed to output the maximum fluctuating steam amount continuously for a time equal to or longer than the startup suppression time), the output steam amount of the boiler 20B temporarily exceeds the can increase reference steam amount set in the boiler 20B. At this time, due to the start-up suppression time, the steaming instruction for immediately starting steaming of the boiler 20B in the combustion stopped state having a high priority cannot be performed. For this reason, a time lag corresponding to the activation suppression time is generated until the steaming of the boiler 20B in the combustion stopped state is started. As a result, the header pressure decreases during this period, and the header pressure becomes unstable.

Therefore, the maximum fluctuation steam amount of the continuous control boiler 20B and the first time are calculated from the sum of the steam amount corresponding to the combustion position where the predetermined steam amount can be combusted in the step value control boiler 20A and the increase reference steam amount of the continuous control boiler 20B. It is set to be smaller than a value obtained by subtracting the product with (for example, a value equal to or longer than the activation suppression time).
As an example, from the sum of the amount of steam corresponding to the combustion position where the predetermined steam amount can be combusted in the step-value control boiler 20A and the standard increase amount of steam in the continuous control boiler 20B, The minimum combustion state of the continuous control boiler 20B that is smaller than the value obtained by subtracting the product of one hour (for example, a value that is equal to or greater than the startup suppression time) and that is less than the amount of steam corresponding to the combustion position that can be burned in the step value control boiler 20A. The minimum amount of steam corresponding to S1 is increased. The predetermined steam amount is set to be equal to or greater than the sum of the steam amount corresponding to the combustion position where combustion can be performed in the step value control boiler 20A and the steam amount corresponding to the lower limit value of the eco-operation zone of the continuous control boiler 20B. Also good.
Thus, after the switching by the output switching unit 42, the maximum fluctuation steam amount is output continuously for the first time (for example, a time longer than the startup suppression time) to the continuous control boiler 20B that is the switching target. Even when the combustion is instructed, the output steam amount of the continuous control boiler 20B does not reach the canned reference steam amount. Therefore, load follow-up is possible without causing a decrease in the pressure inside the steam header 6, and the boiler system 1 can be stably operated.
When the predetermined steam amount is larger by the minimum steam amount corresponding to the minimum combustion state S1 of the continuous control boiler 20B than the steam amount corresponding to the combustion position capable of combustion in the step value control boiler 20A, the output switching unit Even when the combustion rate of the continuous control boiler 20B is reduced by switching 42, the combustion rate of the continuous control boiler 20B is reduced only to the minimum combustion state S1, and the combustion of the continuous control boiler 20B may stop. Absent.
Further, when the predetermined steam amount is equal to or greater than the sum of the steam amount corresponding to the combustion position where combustion is possible in the step value control boiler 20A and the steam amount corresponding to the lower limit value of the eco-operation zone of the continuous control boiler 20B, Even when the combustion rate of the continuous control boiler 20B is reduced due to the switching of the output switching unit 42, the combustion rate of the continuous control boiler 20B is reduced only to the lower limit value of the eco-operation zone, and the continuous control boiler 20B is efficiently operated. The boiler system 1 can be operated efficiently.

(Rapid reduction in steam consumption after switching)
In the combustion control of the continuous control boiler group 2B, when a combustion instruction is issued to reduce the combustion rate of one continuous control boiler 20B having a lower priority in the continuous control boiler group 2B, a predetermined suppression time (for example, 3 Until the second) elapses, the continuous control boiler 20B cannot be instructed to stop combustion.
For this reason, after the combustion rate of the continuous control boiler 20B is decreased by switching the output switching unit 42, the combustion is performed so as to decrease the maximum fluctuation steam amount continuously for a second time (for example, a time longer than the suppression time). When instructed, if the output steam amount of the continuous control boiler 20B falls below the reference reduction steam amount set in the boiler 20B, until the can reduction instruction after issuing the combustion instruction to the continuous control boiler 20B Because of this suppression time, the continuous control boiler 20B cannot be stopped immediately. For this reason, a time lag corresponding to the suppression time is generated until the combustion of the continuous control boiler 20B is stopped. As a result, the header pressure increases during that time, and the header pressure becomes unstable.

Therefore, as an example, the steam amount corresponding to the combustion position where the predetermined steam amount can be combusted in the step-value control boiler 20A, the reduced reference steam amount, the product of the maximum fluctuation steam amount and the preset second time. It is set to be larger than the sum of.
Thereby, after the switching by the output switching unit 42, the maximum fluctuation steam amount is continuously decreased for the second time (for example, a time equal to or longer than the suppression time) for the continuous control boiler 20B to be switched. Even in the case where combustion is instructed, the output steam amount of the continuous control boiler 20B does not reach the reduced steam reference steam amount. Therefore, the header pressure does not increase. Further, even when the combustion rate of the continuous control boiler 20B is reduced due to the switching of the output switching unit 42, the output steam amount of the continuous control boiler 20B does not reach the reduced steam reference steam amount and the combustion of the continuous control boiler 20B. Will not stop.

Next, a case where the predetermined steam amount is set from the viewpoint of efficient combustion of the continuous control boiler 20B will be described.
As described above, the combustion control range (eco-operation zone) with high boiler efficiency is set in the continuous control boiler 20B. By continuously burning the continuous control boiler 20B in this eco-operation zone, the continuous control boiler 20B can be efficiently burned.
Therefore, even when the combustion rate of the continuous control boiler 20B is reduced due to the switching of the output switching unit 42, the predetermined steam amount is set so that the combustion rate of the continuous control boiler 20B is within the range of the eco operation zone. As an example, the amount of steam that is output by the amount of steam that is output at the combustion rate at the lower limit value of the eco-operation zone is set as the predetermined steam amount from the combustion position at which combustion is possible in the stage value control boiler 20A. Thereby, the continuous control boiler 20B can be continuously burned within the range of the eco-operation zone.

Note that switching from the continuous control boiler 20B to the step value control boiler 20A as described above is performed when the required load increases. On the other hand, when the required load decreases, the output switching unit 42 switches from the step value control boiler 20A to the continuous control boiler 20B. In other words, the output switching unit 42 is a steam that the step value control boiler 20A outputs on condition that the steam amount output from the continuous control boiler 20B reaches a specific steam amount in a state where the step value control boiler 20A is burning. The amount is switched to the continuous control boiler 20B.
Although details will be described later, the output switching unit 42 switches the output of the steam amount from the step value control boiler 20A to the continuous control boiler 20B according to the priority order set in the step value control boiler 20A. As an example, when all of the stage value control boilers 20A are combusting, the high combustion position H of the No. 3 boiler with the ninth priority is the lowest priority. Therefore, the output switching unit 42 changes the combustion position of the No. 3 boiler from the high combustion position H to the middle combustion position M on condition that the amount of steam output from the continuous control boiler 20B reaches the specific steam amount. The output of the steam amount (high combustion position H−medium combustion position M) corresponding to the high combustion position H of the No. 3 boiler is switched from the No. 3 boiler to the continuous control boiler 20B.

  The specific steam amount can be arbitrarily set similarly to the predetermined steam amount. In the present embodiment, as an example, the minimum steam amount of the continuous control boiler 20B or the steam amount output at the combustion rate of the lower limit value of the eco-operation zone of the continuous control boiler 20B is set as the specific steam amount.

The configuration of the boiler system 1 has been described above. Next, the operation of the boiler system 1 will be described. FIG. 5 shows the operation when the steam amount output is switched from the continuous control boiler 20B to the step value control boiler 20A, and FIG. 6 shows the case where the steam amount output is switched from the step value control boiler 20A to the continuous control boiler 20B. The operation is shown. FIG. 5 shows the operation when the predetermined steam amount is set to a steam amount that is larger by the minimum steam amount of the continuous control boiler 20B than the combustion position at which combustion is possible in the step value control boiler 20A. FIG. The operation when the minimum steam amount of the continuous control boiler 20B is set as the steam amount is shown.
Also, in FIGS. 5 and 6, for the sake of simplicity, the boiler group 2 is constituted by a total of three boilers 20A and 20B, that is, two step value control boilers 20A and one continuous control boiler 20B. It is assumed that priorities are set in the order of (1) to (6) in the figure for the two stage value control boilers 20A.

Referring to FIG. 5A1, the stage value control boiler 20A stops combustion, and the continuous control boiler 20B burns in the minimum combustion state S1. At this time, when the required load increases, the output control unit 41 increases the combustion rate of the continuous control boiler 20B, and causes the amount of steam output from the boiler group 2 to follow the required load.
As a result, as shown in FIG. 5 (B1), the amount of steam output from the continuous control boiler 20B is lower than the minimum amount of steam of the continuous control boiler 20B. It increases to a steam amount (predetermined steam amount) that is increased by the steam amount (+ α) output at the combustion position L). Note that + α is a surplus amount for ensuring the stability of the boiler system 1.

  When the steam amount output from the continuous control boiler 20B reaches the predetermined steam amount in this way, the output switching unit 42 switches the output of the steam amount from the continuous control boiler 20B to the step value control boiler 20A. Specifically, as shown in FIG. 5 (C1), the low combustion position L of the first priority level of the stage value control boiler 20A that has stopped combustion starts combustion, while the output from the continuous control boiler 20B. The amount of steam to be reduced is reduced by an amount corresponding to the low combustion position L.

  Thereafter, similarly, the output control unit 41 causes the steam amount output from the continuous control boiler 20B to be the combustion position (medium combustion position M) of the second priority of the step value control boiler 20A over the minimum steam amount of the continuous control boiler 20B. ) Increases to the amount of steam (predetermined amount of steam) that is increased by the amount of steam output (+ α) (FIG. 5 (D1)), the output switching unit 42 gives priority to the amount of steam output from the continuous control boiler 20B. It switches to the stage value control boiler 20A (medium combustion position M) of the second rank (FIG. 5 (E1)).

  Similarly, after that, the steam amount output from the continuous control boiler 20B by the output control unit 41 is higher than the minimum steam amount of the continuous control boiler 20B. When the steam amount (predetermined steam amount) increased by the steam amount (+ α) output at the sixth combustion position is increased, the output switching unit 42 converts the steam amount output from the continuous control boiler 20B to the step value control boiler. Switch to 20A (FIG. 5 (F1) to (N1)).

  Subsequently, referring to FIG. 6 (A2), the stage value control boiler 20A burns all from the first priority to the sixth rank, and the continuous control boiler 20B burns at a predetermined combustion rate. At this time, when the required load decreases, the output control unit 41 decreases the combustion rate of the continuous control boiler 20B, and causes the amount of steam output from the boiler group 2 to follow the required load.

As a result, as shown in FIG. 6 (B2), the steam amount output from the continuous control boiler 20B decreases to the minimum steam amount of the continuous control boiler 20B.
Then, the output switching unit 42 switches the output of the steam amount from the step value control boiler 20A to the continuous control boiler 20B. Specifically, as shown in FIG. 6 (C2), the steam output from the continuous control boiler 20B is stopped while the combustion at the high combustion position H of the sixth priority of the stage value control boiler 20A that has been burning is stopped. The amount is increased by an amount corresponding to the high combustion position H.

  Thereafter, similarly, when the amount of steam output from the continuous control boiler 20B is reduced to the minimum amount of steam by the output control unit 41 (FIG. 6 (D2)), the output switching unit 42 is the fifth-priority step value control boiler. The steam amount output by 20A (high combustion position H) is switched to the continuous control boiler 20B (FIG. 6 (E2)).

  Similarly, when the output controller 41 reduces the amount of steam output from the continuous control boiler 20B to the minimum amount of steam, the output switching unit 42 is in the fourth priority, third, second, and first stages. The steam amount output by the value control boiler 20A is switched to the continuous control boiler 20B (FIG. 6 (F2) to (N2)).

  Subsequently, as the predetermined steam amount, the operation when the steam amount that is larger by the steam amount that is output at the combustion rate of the lower limit value of the eco-operation zone than the combustion position that can be combusted in the stage value control boiler 20A is set and specified The operation when the steam amount output at the combustion rate of the lower limit value of the eco-operation zone is set as the steam amount will be described with reference to FIGS.

  Referring to FIG. 7, (A1) to (C1) correspond to FIGS. 5 (A1) to (C1), and are continuous as a predetermined steam amount from the combustion position where combustion is possible in the stage value control boiler 20A. Operation | movement at the time of setting the steam amount larger by the minimum steam amount of the control boiler 20B is shown. On the other hand, in (A3) to (C3), as the predetermined steam amount, a steam amount that is larger by the steam amount that is output at the combustion rate of the lower limit value of the eco-operation zone than the combustion position at which combustion is possible in the stage value control boiler 20A The operation is shown below.

7 (A1) to (C1) and FIGS. 7 (A3) to (C3) have different timings for switching the amount of steam output from the continuous control boiler 20B to the step value control boiler 20A. That is, in FIGS. 7A1 to 7C1, when the steam amount output from the continuous control boiler 20B becomes a steam amount that is larger by the minimum steam amount (+ α) than the combustion position at which the stage value control boiler 20A can combust. While the output of the steam amount is switched to the step value control boiler 20A, in FIG. 7 (A3) to (C3), the steam amount output from the continuous control boiler 20B is combustible in the step value control boiler 20A. When the amount of steam is larger than the combustion position by the amount of steam (+ α) output at the lower combustion rate of the eco-operation zone, the output of the amount of steam is switched to the stage value control boiler 20A.
By switching the output of the steam amount as shown in FIGS. 7A3 to 7C, it is preferable that the continuous control boiler 20B can be burned in the range of the eco-operation zone even after the switching.

Referring to FIG. 8, (A2) to (C2) correspond to FIGS. 6 (A2) to (C2), and the operation when the minimum steam amount of continuous control boiler 20B is set as the specific steam amount. Indicates. On the other hand, (A4) to (C4) show the operation when the steam amount output at the combustion rate of the lower limit value of the eco-operation zone is set as the specific steam amount.
8 (A4) to (C4), the boiler group 2 is configured by a total of four boilers 20A and 20B, that is, two step value control boilers 20A and two continuous control boilers 20B.

8 (A2) to (C2) and FIGS. 8 (A4) to (C4) differ in timing for switching the amount of steam output from the step value control boiler 20A to the continuous control boiler 20B. That is, in FIGS. 8A2 to 8C2, when the steam amount output from the continuous control boiler 20B decreases to the minimum steam amount, the output of the steam amount is switched from the step value control boiler 20A to the continuous control boiler 20B. On the other hand, in FIGS. 8A4 to 8C4, when the steam amount output from the continuous control boiler 20B decreases to the steam amount output at the combustion rate of the lower limit value of the eco-operation zone, the step value control boiler 20A The steam amount output is switched to the continuous control boiler 20B.
By switching the output of the steam amount as shown in FIGS. 8A4 to 8C4, the continuous control boiler 20B can be burned for a long time in the range of the eco operation zone, which is preferable.

By the way, in FIG. 8 (A2)-(C2), there is one continuous control boiler 20B, but in FIG. 8 (A4)-(C4), there are two continuous control boilers 20B.
In this regard, when there is one continuous control boiler 20B, when the amount of steam output from the step value control boiler 20A to the continuous control boiler 20B is switched, the amount of steam to be switched is assigned only to the continuous control boiler 20B. . Referring to FIGS. 8B2 and C2, the output switching unit 42 switches the steam amount corresponding to the high combustion position H of the sixth priority of the step value control boiler 20A to one continuous control boiler 20B. ing. That is, the amount of steam output from the continuous control boiler 20B increases by the amount of steam corresponding to the high combustion position H of the sixth priority.
On the other hand, when the number of continuous control boilers 20B is two (plural), when the amount of steam output from the step value control boiler 20A to the continuous control boiler 20B is switched, the amount of steam switched to the two (plural) continuous control boilers 20B. Will be allocated. Referring to FIGS. 8 (B4) and (C4), the output switching unit 42 switches the steam amount corresponding to the high combustion position H of the sixth priority of the step value control boiler 20A to the two continuous control boilers 20B. ing. That is, the amount of steam output from each of the two continuous control boilers 20B increases by half of the amount of steam corresponding to the high combustion position H of the sixth priority.

(Rapid increase in steam consumption after switching)
Next, as the predetermined steam amount, the maximum fluctuation steam amount of the continuous control boiler 20B is obtained from the sum of the steam amount corresponding to the combustion position combustible in the stage value control boiler 20A and the increase reference steam amount of the continuous control boiler 20B. The value of the continuous control boiler 20B is set to be smaller than a value obtained by subtracting the product of the first time (for example, a value equal to or longer than the startup suppression time) and the steam amount corresponding to the combustion position combustible in the step value control boiler 20A. The operation in the case of setting so as to increase by the minimum steam amount corresponding to the minimum combustion state S1 will be described with reference to FIGS. 9 (A′1) to (F′1).

As shown in FIGS. 9 (B′1) and (C′1), when the predetermined steam amount is reached, the output of the steam amount is switched to the step value control boiler 20A.
Thereafter, as shown in FIGS. 9 (D′ 1) to (F′1), the combustion is instructed to output the maximum fluctuating steam amount continuously for the first time (for example, the time equal to or longer than the activation suppression time). Even if it exists, the output steam amount of the said continuous control boiler 20B does not reach the can increase reference | standard steam amount. Therefore, load follow-up is possible without causing a decrease in header pressure, and the boiler system 1 can be stably operated. Further, even when the combustion rate of the continuous control boiler 20B is reduced by switching the output switching unit 42, the combustion rate of the continuous control boiler 20B is reduced only to the minimum combustion state S1, and the combustion of the continuous control boiler 20B is performed. Will not stop.

  Further, from the sum of the steam amount corresponding to the combustion position where the predetermined steam amount can be combusted in the step-value control boiler 20A and the reference increase steam amount of the continuous control boiler 20B, the maximum fluctuation steam amount of the continuous control boiler 20B The amount of steam corresponding to the combustion position at which combustion is possible in the stage value control boiler 20A is set smaller than the value obtained by subtracting the product of the first time (for example, a value equal to or greater than the start suppression time) and The operation in the case of setting so as to increase by the amount of steam corresponding to the lower limit value of the operation zone will be described with reference to FIGS. 10 (A′2) to (F′2).

As shown in FIGS. 10 (B′2) and (C′2), when the predetermined steam amount is reached, the output of the steam amount is switched to the step value control boiler 20A.
Thereafter, as shown in FIGS. 10 (D′ 2) to (F′2), the combustion is instructed to output the maximum fluctuating steam amount continuously for the first time (for example, the time equal to or longer than the activation suppression time). Even if it exists, the output steam amount of the said continuous control boiler 20B does not reach the can increase reference | standard steam amount. Therefore, load follow-up is possible without causing a decrease in header pressure, and the boiler system 1 can be stably operated. Furthermore, after switching, the continuous control boiler 20B can be burned in the range of the eco-operation zone.

(Rapid reduction in steam consumption after switching)
Next, as a predetermined steam amount, a steam amount corresponding to a combustion position that can be combusted in the stage value control boiler 20A, a reduced steam reference steam amount, a maximum fluctuation steam amount of the continuous control boiler 20B, and a preset second time. The operation when set so as to be larger than the product of and the sum of these will be described with reference to FIGS. 11 (A′3) to (F′3).

As shown in FIGS. 11 (B′3) to (C′3), when the predetermined steam amount is reached, the output of the steam amount is switched to the step value control boiler 20A.
Thereafter, as shown in FIGS. 11 (D′ 3) to (F′3), the combustion is instructed so as to reduce the maximum fluctuation steam amount continuously for the second time (for example, the time longer than the suppression time). However, the output steam amount of the continuous control boiler 20B does not reach the reduced steam reference steam amount. Therefore, load follow-up is possible without causing an increase in header pressure, and the boiler system 1 can be stably operated. Further, even when the combustion rate of the continuous control boiler 20B is reduced due to the switching of the output switching unit 42, the output steam amount of the continuous control boiler 20B does not reach the reduced steam reference steam amount and the combustion of the continuous control boiler 20B. Will not stop.

The example of the operation of the boiler system 1 has been described above. By the way, as described above, the stage value control boiler 20A has a combustion position (eco-combustion position) having the highest combustion efficiency in burning among the plurality of combustion positions. In this regard, in FIGS. 5 to 11, the boiler efficiency of the step value control boiler 20 </ b> A is not considered, but the output steam amount may be switched in consideration of the efficiency of the step value control boiler 20 </ b> A.
FIG. 12 is a diagram illustrating the operation of the boiler system 1 when the boiler efficiency of the step value control boiler 20A is taken into consideration. 12 (I1) to (K1) correspond to FIGS. 5 (I1) to (K1). 12 (I5) to (K5) show an operation example when there are two continuous control boilers 20B. As described above, when there are two (a plurality) of continuous control boilers 20B, the amount of steam switched by the output switching unit 42 is a value obtained by dividing the number of continuous control boilers 20B by the number of continuous control boilers 20B.

Referring to FIG. 12 (I1), as a result of the output of the steam amount being switched from continuous control boiler 20B to stage value control boiler 20A, stage value control boiler 20A burns at medium combustion position M at the fourth priority. ing. Here, it is assumed that the middle combustion position M of the stage value control boiler 20A is an eco combustion position.
When the boiler efficiency of the step value control boiler 20A is not taken into account, after that, when the amount of steam output from the continuous control boiler 20B increases to a predetermined amount of steam (FIG. 12 (J1)), the output switching unit 42 causes the continuous control boiler 20B. To switch the amount of steam to be output to the step value control boiler 20A. As a result, as shown in FIG. 12 (K1), the stage value control boiler 20A deviates from the eco combustion position and burns at the high combustion position H.

With reference to FIGS. 12 (I5) to (K5), the operation when the boiler efficiency of the step value control boiler 20A is considered will be described. In FIG. 12 (I5), the stage value control boiler 20A burns at the eco combustion position (medium combustion position M).
Thereafter, when the required load increases, as shown in FIG. 12 (J5), the amount of steam output from the continuous control boiler 20B increases to a predetermined amount of steam. In FIG. 12 (J5), since there are two continuous control boilers 20B, the amount of steam output from each of the two continuous control boilers 20B is higher than the minimum steam amount in the high combustion ranking of 5th. The timing at which the amount of steam corresponding to the position H is increased by half is the timing at which the amount of steam output from the continuous control boiler 20B is increased to a predetermined amount of steam.

When the boiler efficiency of the step value control boiler 20A is not taken into consideration, the output switching unit 42 determines the step value from the continuous control boiler 20B according to the increase in the amount of steam output from the continuous control boiler 20B to a predetermined steam amount. The steam amount output is switched to the control boiler 20A. On the other hand, when considering the boiler efficiency of the step value control boiler 20A, the output switching unit 42 determines the step value from the continuous control boiler 20B even if the amount of steam output from the continuous control boiler 20B increases to a predetermined steam amount. There is no need to switch the output of the steam amount to the control boiler 20A. As a result, as shown in FIG. 12 (K5), the amount of steam output from the continuous control boiler 20B increases beyond the predetermined amount of steam.
Thereby, stage value control boiler 20A can be burned efficiently. In this case, when the combustion rate of the continuous control boiler 20B increases to the maximum combustion rate, the output switching unit 42 switches the output of the steam amount from the continuous control boiler 20B to the step value control boiler 20A.

  According to the boiler system 1 of this embodiment demonstrated above, there exist the following effects.

(1) In the boiler system 1 of the present embodiment, when the required load increases, the output control unit 41 increases the amount of steam output from the continuous control boiler 20B, thereby causing the output steam amount to follow the required load. . When the amount of steam output from the continuous control boiler 20B reaches a predetermined amount of steam that exceeds the amount of steam corresponding to the combustion position with the highest priority of the step value control boiler 20A, the output switching unit 42 moves to this combustion position. The corresponding steam amount output is switched from the continuous control boiler 20B to the step value control boiler 20A.
That is, when the continuous control boiler 20B capable of continuously changing the combustion rate is used for adjusting the error with the required load, the error increases when the error increases to correspond to the combustion position of the step value control boiler 20A. The stage value control boiler 20A is assigned to assume that it is generated constantly. Thereby, the continuous control boiler 20B can be used for load following with respect to the required load, while the step value control boiler 20A can be used for base combustion with respect to the amount of steam that is constantly required. As a result, the number control utilizing the superiority of both boilers becomes possible.

  (2) Further, by setting a steam amount that is larger than the steam amount corresponding to the combustion position of the stage value control boiler 20A by the minimum steam amount that can be output by the continuous control boiler 20B as the predetermined steam amount, the continuous control boiler 20B Even if the amount of steam to be output to the step value control boiler 20A is switched, the continuous control boiler 20B can continue to burn. That is, the amount of steam to be output can be switched without accompanying the start / stop of the continuous control boiler 20B, and the boiler system 1 can be stably operated.

  (3) Moreover, continuous control is performed by setting a steam amount that is larger by the steam amount corresponding to the lower limit value of the eco-operation zone of the continuous control boiler 20B than the combustion position at which combustion is possible in the step value control boiler 20A as the predetermined steam amount. Even if the amount of steam output from the boiler 20B to the step-value control boiler 20A is switched, the continuous control boiler 20B can be burned in the range of the eco-operation zone. That is, the continuous control boiler 20B can be burned efficiently, and the boiler system 1 can be operated efficiently.

  (4) Further, from the sum of the steam amount corresponding to the combustion position where the predetermined steam amount can be combusted in the step-value control boiler 20A and the canned reference steam amount, the maximum fluctuation steam amount and the first time (for example, the start suppression time) The product with the above value) is set to be smaller than the subtracted value. Thus, after the switching by the output switching unit 42, the maximum fluctuation steam amount is output continuously for the first time (for example, a time longer than the startup suppression time) to the continuous control boiler 20B that is the switching target. Even when the combustion is instructed, the output steam amount of the continuous control boiler 20B does not reach the increased reference steam amount, so that the load follow-up can be performed without causing a decrease in the pressure inside the steam header 6. Thus, the boiler system 1 can be stably operated.

  (5) Further, by setting the predetermined steam amount to be larger than the steam amount corresponding to the combustion position of the step value control boiler 20A by the minimum steam amount that can be output by the continuous control boiler 20B, the step value control is performed from the continuous control boiler 20B. Even if the amount of steam output to the boiler 20A is switched, the continuous control boiler 20B can continue to burn. That is, the amount of steam to be output can be switched without accompanying the start / stop of the continuous control boiler 20B, and the boiler system 1 can be stably operated.

  (6) Furthermore, by setting the predetermined steam amount to be larger by the steam amount corresponding to the lower limit value of the eco-operation zone of the continuous control boiler 20B than the steam amount corresponding to the combustion position where combustion is possible in the step value control boiler 20A, Even if the amount of steam output from the continuous control boiler 20B to the step value control boiler 20A is switched, the continuous control boiler 20B can be burned in the range of the eco-operation zone. That is, the continuous control boiler 20B can be burned efficiently, and the boiler system 1 can be operated efficiently.

  (7) Further, the predetermined steam amount is a steam amount corresponding to a combustion position where combustion can be performed in the step-value control boiler 20A, the reduced steam reference steam amount, the maximum fluctuation steam amount of the continuous control boiler 20B, and a second preset value. Set to be greater than the sum of products with time. Thereby, after the switching by the output switching unit 42, the maximum fluctuation steam amount is continuously decreased for the second time (for example, a time equal to or longer than the suppression time) for the continuous control boiler 20B to be switched. Even when the combustion is instructed, the output steam amount of the continuous control boiler 20B does not reach the reduced steam reference steam amount. Therefore, load follow-up is possible without causing an increase in pressure inside the steam header 6, and the boiler system 1 can be operated stably. Further, even when the combustion rate of the continuous control boiler 20B is lowered due to the switching of the output switching unit 42, the output steam amount of the continuous control boiler 20B does not fall below the canned reference steam amount, and the continuous control boiler 20B burns. Never stop.

  (8) Further, when the step value control boiler 20A is combusting at the eco-combustion position, even if the steam amount output from the continuous control boiler reaches a predetermined steam amount, switching by the output switching unit 42 is not performed. Thereby, the stage value control boiler 20A for base combustion can be continuously burned efficiently, and the boiler system 1 can be operated efficiently.

The preferred embodiment of the boiler system 1 of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and can be modified as appropriate.
For example, in the present embodiment, the present invention is applied to the boiler system including the boiler group 2 including the five boilers 20A and 20B, but is not limited thereto. That is, the present invention is applicable to any boiler group 2 in which one or more step value control boilers 20A and one or more continuous control boilers 20B are mixed.

  In the above embodiment, the predetermined steam amount and the specific steam amount are set based on the lower limit value of the eco operation zone of the continuous control boiler 20B. In this respect, the setting based on the lower limit value of the eco-operation zone is for burning the continuous control boiler 20B within the range of the eco-operation zone before and after switching. It may be performed based on any value within the range.

DESCRIPTION OF SYMBOLS 1 Boiler system 2 Boiler group 20A Step value control boiler 20B Continuous control boiler 3 Number control apparatus 4 Control part 41 Output control part 42 Output switching part 5 Storage part

Claims (5)

A stage value control boiler capable of burning at a plurality of staged combustion positions, a boiler group including a plurality of continuous control boilers capable of burning by continuously changing a combustion rate, and a combustion state of the boiler group according to a required load A boiler system comprising a control unit for controlling
In the plurality of continuous control boilers, a maximum variable steam amount that is an upper limit value of the steam amount that can change per unit time, and a can increase reference steam amount that serves as a reference for increasing the number of the continuous control boilers to be burned are set. Has been
The controller is
An output control unit for controlling the combustion state of the boiler group so as to output steam for the required steam amount according to the required load from the continuous control boiler;
On the condition that the steam amount output from the continuous control boiler reaches a predetermined steam amount exceeding the steam amount corresponding to the combustion position combustible in the step value control boiler, the output of the steam amount corresponding to the combustion position is An output switching unit for switching from the continuous control boiler to the step value control boiler;
With
The predetermined steam amount is a value smaller than a value obtained by subtracting a product of the maximum variation steam amount and a preset first time from the sum of the steam amount corresponding to the combustion position and the canned reference steam amount. Boiler system set to.
In the continuous control boiler, a minimum combustion steam amount that is a steam amount in the minimum combustion state of the continuous control boiler is set,
The boiler system according to claim 1, wherein the predetermined steam amount is equal to or greater than a sum of a steam amount corresponding to the combustion position and the minimum combustion steam amount.
The boiler system according to claim 1 or 2, wherein the first time is a time equal to or longer than an activation suppression time until a can increase instruction is issued after a combustion instruction is issued to one continuous control boiler.
A stage value control boiler capable of burning at a plurality of staged combustion positions and a boiler group including a continuous control boiler capable of burning by continuously changing the combustion rate, and controlling the combustion state of the boiler group according to a required load A boiler system comprising:
The continuous control boiler is set with a maximum fluctuation steam amount that is an upper limit value of the steam amount that can fluctuate per unit time, and a can reduction reference steam amount that serves as a reference for reducing the number of the continuous control boilers to be burned. And
The controller is
An output control unit for controlling the combustion state of the boiler group so as to output steam for the required steam amount according to the required load from the continuous control boiler;
On the condition that the steam amount output from the continuous control boiler reaches a predetermined steam amount exceeding the steam amount corresponding to the combustion position combustible in the step value control boiler, the output of the steam amount corresponding to the combustion position is An output switching unit for switching from the continuous control boiler to the step value control boiler;
With
The predetermined steam amount is larger than the sum of the amount of steam corresponding to the combustion position, the reference steam amount for can reduction, and the amount of steam obtained by adding a second time preset to the maximum variable steam amount. system.
  The boiler system according to claim 4, wherein the second time is a time equal to or longer than a suppression time until a can reduction instruction can be issued after issuing a combustion instruction to one continuous control boiler.

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