JP6028608B2 - Boiler system - Google Patents

Description

  The present invention relates to a boiler system including a boiler group having a plurality of boilers capable of burning at a plurality of stepwise combustion positions.

Conventionally, in a boiler system comprising a boiler group having a plurality of boilers combustible at a plurality of combustion positions, and a control unit that controls the boiler group, the combustion positions of the plurality of boilers are controlled in stages. The amount of steam output from the group is to be adjusted.
In such a boiler system based on step value control, when combustion of a boiler in a stopped state is started, the amount of steam is reduced by backing up the shortage that occurs until the boiler can be steamed by another boiler. It will make up for the shortage.

  By the way, when performing backup using a boiler with a large turndown ratio, the amount of steam due to backup becomes excessive relative to the shortage. In order to eliminate such an excessive backup, in recent years, a device for controlling the backup timing according to the pressure gradient of the steam header is known (for example, Patent Document 1).

JP 2010-91139 A

  According to a device such as Patent Document 1, although the backup timing is adjusted according to the pressure gradient (decrease rate) of the steam header, the amount of steam can be prevented from being excessive, but there is room for further improvement. . Specifically, in the conventional backup, the amount of steam required for the boiler that needs to be backed up (backup requested amount), and the amount of steam that is increased for the backup required for the backup boiler (backup steam amount) Thus, the timing for performing the backup is calculated by comparing only, and a device for adjusting the backup timing with higher accuracy is required.

  The present invention has been made in view of such a demand, and an object thereof is to provide a boiler system that can be backed up at a more appropriate timing.

  Whether or not the amount of steam becomes excessive due to backup is determined by whether or not the amount of steam after backup exceeds the amount of steam necessary for the required load (the required amount of steam). Therefore, the present inventor does not compare only the two pieces of information of the backup request amount and the backup steam amount as in the past, but more appropriately by referring to and comparing the necessary steam amount in addition to both information. It was possible to back up at an appropriate timing.

  Specifically, the present invention provides a boiler group including a plurality of boilers capable of increasing or decreasing the combustion amount in stages according to a selected combustion position, and a control for controlling the combustion state of the boiler group according to a required load. A backup determination unit for determining whether or not a backup by a second boiler is necessary for a combustion instruction to the first boiler, and the first boiler. A backup request amount calculation unit that calculates a steam amount according to a combustion instruction to the engine as a backup request amount, and a backup steam amount that calculates a steam amount that increases when the combustion position of the second boiler is increased by one step as a backup steam amount When the calculation unit and the backup determination unit determine that the backup is necessary, the current steam amount and the boiler group corresponding to the required load are determined. With respect to the second boiler, on condition that the first difference that is the difference between the instruction steam amount that instructs the output exceeds the second difference that is the difference between the backup steam amount and the backup request amount. The present invention relates to a boiler system including a backup instruction unit that issues a backup instruction.

  In addition, the backup instructing unit, on the condition that the difference between the first difference and the second difference exceeds a predetermined value when the backup determination unit determines that the backup is necessary, the second instruction A backup instruction may be given to the boiler.

  According to the present invention, since the backup is performed by directly referring to the required steam volume, the backup can be performed at an appropriate timing when the steam volume corresponding to the required steam volume is output from the boiler group. As a result, the amount of steam does not become excessive with respect to the required amount of steam at the time of backup, and overshoot, hunting, and the like can be suppressed, so that pressure stability can be improved.

It is a figure showing the outline of the boiler system concerning one embodiment of the present invention. It is a figure showing the outline of the boiler group concerning one embodiment of the present invention. It is a figure which shows the relationship between the combustion pattern and steam pressure zone of each boiler which concerns on one Embodiment of this invention. It is a block diagram which shows the functional structure of the number control apparatus which concerns on one Embodiment of this invention. It is a figure which shows the operation example of the boiler system which concerns on one Embodiment of this invention.

Hereinafter, a preferred embodiment of a boiler system of the present invention will be described with reference to the drawings.
First, the overall configuration of the boiler system 1 of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing an outline of a boiler system according to an embodiment of the present invention.
As shown in FIG. 1, the boiler system 1 includes a boiler group 2 including a plurality (three) of boilers 20, a steam header 6 that collects steam generated in the plurality of boilers 20, and the steam header 6. A vapor pressure sensor 7 for measuring the internal pressure and a number control device 3 having a control unit 4 for controlling the combustion state of the boiler group 2 are provided.

The boiler group 2 produces | generates the vapor | steam supplied to the steam use installation 18 as a load apparatus.
The steam header 6 is connected to a plurality of boilers 20 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 pressure difference and pressure fluctuation of the plurality of boilers 20, and supplying the steam whose pressure is adjusted to the steam using facility 18. Supply.

  The vapor pressure sensor 7 is electrically connected to the number control device 3 via the signal line 13. The steam pressure sensor 7 measures the steam pressure inside the steam header 6 (steam pressure generated in the boiler group 2), and sends a signal (steam pressure signal) related to the measured steam pressure via the signal line 13. It transmits to the control apparatus 3.

  The number control device 3 is electrically connected to the plurality of boilers 20 through the signal line 16. The number control device 3 controls the combustion state of the boiler group 2 by controlling the combustion position of each boiler 20 based on the steam pressure inside the steam header 6 measured by the steam pressure sensor 7. Details of the number control device 3 will be described later.

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 determines the fluctuation of the steam pressure inside the steam header 6 corresponding to the fluctuation of the steam consumption based on the steam pressure (physical quantity) inside the steam header 6 measured by the steam pressure sensor 7. It calculates and controls the combustion position of each boiler 20 which comprises the boiler group 2. FIG.

  Specifically, the demand load (steam consumption) increases due to an increase in demand for the steam use facility 18, and if the supply steam quantity is insufficient, the steam pressure inside the steam header 6 decreases. On the other hand, if the demand load (steam consumption) decreases due to a decrease in the demand of the steam use facility 18, and the supply steam amount becomes excessive, the steam pressure inside the steam header 6 increases. Therefore, the boiler system 1 can monitor the fluctuation of the required load based on the fluctuation of the vapor pressure measured by the vapor pressure sensor 7. Then, the boiler system 1 calculates the required steam amount (required steam amount) according to the consumed steam amount (required load) of the steam using equipment 18 based on the steam pressure of the steam header 6, and The boiler group 2 is burned so that the steam is supplied to the steam header 6.

Here, the several boiler 20 which comprises the boiler system 1 of this embodiment is demonstrated. FIG. 2 is a diagram showing an outline of a boiler group according to an embodiment of the present invention.
The boiler 20 of this embodiment consists of a stage value control boiler having a plurality of staged combustion positions. A step-value control boiler controls the amount of combustion by selectively turning combustion on / off, adjusting the size of the flame, etc., and gradually changes the amount of combustion according to the selected combustion position. It is a boiler that can be increased or decreased.

  The combustion amount at each combustion position of the boiler 20 is set so as to generate an amount of steam corresponding to the pressure difference of the steam pressure in the steam header 6 to be controlled. In the three boilers 20 composed of the step value control boilers, the combustion amount and the combustion capacity at each combustion position may be set to be equal or different from each other.

  As shown in FIG. 2, the boiler 20 in the present embodiment includes a combustion stop position (0%), a low combustion position (25%) as a low combustion position, and a high combustion position (100%) as a high combustion position. It is constituted by a so-called three-position controlled boiler 20 that can be combusted at three combustion positions. In this case, for example, when the combustion amount (steam amount) at the high combustion position of one boiler 20 is 800 kg / h, the combustion amount (steam amount) at the low combustion position is 200 kg / h.

  The N position control represents that the combustion amount of the step value control boiler can be controlled step by step to the N position including the combustion stop position. The number of combustion positions may be four positions (combustion stop position, low combustion position, middle combustion position, and high combustion position) or more.

  Moreover, the priority order is set to each of the plurality of boilers 20. The priority order is used to select the boiler 20 that performs a combustion instruction or a combustion stop instruction. The priority order can be set, for example, using an integer value so that the lower the numerical value, the higher the priority order. As shown in FIG. 2, when the priorities of “1” to “3” are assigned to the first to third units of the boiler 20, the first unit has the highest priority and the third unit has the highest priority. Lowest. This priority order is changed at predetermined time intervals (for example, 24 hour intervals) under the control of the control unit 4 described later.

In the boiler group 2 described above, a plurality of combustion patterns are set that are combinations of the boilers 20 and their combustion positions. FIG. 3 is a diagram showing the relationship between the combustion pattern of each boiler according to an embodiment of the present invention and the pressure zone of the steam header 6 in the pressure control range.
The combustion pattern consists of the type of boiler and the combustion position of the boiler. In FIG. 3, “H” indicates that the boiler 20 is to be burned at the high combustion position, “L” indicates that the boiler 20 is to be burned at the low combustion position, and “−” indicates that the boiler 20 is at the combustion stop position. The combustion positions are shown in order from the left according to the priority order of 20. That is, [(H) (L) (L)] of the combustion pattern E is a state where the boiler 20 with the first priority is burned at the high combustion position, and the boiler 20 with the second priority is burned at the low combustion position. It shows that it is set as a state and it is set as the state which burns the boiler 20 of priority 3rd in a low combustion position.

  As the combustion pattern, a pattern in which the amount of steam output from the boiler group 2 is smaller as the pressure of the steam header 6 becomes higher, that is, the required load becomes smaller, is selected. A pattern with a larger amount of steam output from the boiler group 2 is selected as it increases. As shown in FIG. 3, in the present embodiment, the pressure control range is divided into seven vapor pressure zones a to g. And the boiler system 1 sets the corresponding combustion pattern, ie, a combustion position, for every steam pressure zone, and determines a combustion amount by which pressure zone the pressure of the steam header 6 respond | corresponds. Seven combustion patterns are set corresponding to seven vapor pressure zones.

  In this embodiment, as shown in FIG. 3, when the vapor pressure decreases from the highest vapor pressure zone a toward the lowest vapor pressure zone g, the boiler with the highest priority (here, No. 1) After the boiler is changed from the combustion stop position (−) to the low combustion position (L), the next highest boiler (here, No. 2 boiler) is changed from the combustion stop position (−) to the low combustion position (L). Be changed. And after all the boilers 20 are changed to the low combustion position (L), the boiler 20 having the highest priority (here, No. 1 boiler) is changed to the high combustion position (H) in order.

Returning to FIG. 1, the boiler 20 includes a boiler body 21 in which combustion is performed, and a local control unit 22 that controls the combustion position of the boiler 20.
The local control unit 22 changes the combustion position of the boiler 20 according to the required load. Specifically, the local control unit 22 controls the combustion position of the boiler 20 based on the number control signal transmitted from the number control device 3 via the signal line 16.
Further, the local control unit 22 transmits a signal used in the number control device 3 to the number control device 3 via the signal line 16. Examples of the signal used in the number control device 3 include the actual combustion position of the boiler 20 and other data.

Next, details of the number control device 3 will be described.
The number control device 3 calculates the combustion position of each boiler 20 corresponding to the required combustion amount of the boiler group 2 corresponding to the required load and the required combustion amount based on the steam pressure signal from the steam pressure sensor 7, and each boiler. The number control signal is transmitted to 20 (local control unit 25). As shown in FIG. 1, the number control device 3 includes a storage unit 5 and a control unit 4.

  The storage unit 5 includes information on instructions given to each boiler 20 under the control of the number control device 3 (control unit 4), information such as the combustion position received from each boiler 20, and combustion patterns of a plurality of boilers 20. Information on setting conditions, information on setting priorities of a plurality of boilers 20, information on settings on changing priority (rotation), and the like.

  The control unit 4 gives various instructions (number control signal) to each boiler 20 via the signal line 16 and receives various data from each boiler 20 to determine the combustion positions of the three boilers 20. Control priority. When each boiler 20 receives a signal for changing the combustion position from the number control device 3, it controls the boiler 20 according to the instruction.

  By the way, if the state located in the combustion stop position (−) continues for a certain period of time, the boiler 20 is cooled, and even if controlled by the control unit 4 to be located in the low combustion position (L), the low combustion position (L) immediately. It is not possible to output steam with a steam amount (200 kg / h) corresponding to. In such a case, the control unit 4 may instruct the other boiler 20 that can output steam to output the insufficient steam instead, thereby preventing the steam shortage. Such another boiler 20 outputting steam instead is hereinafter referred to as “backup” and sometimes referred to as “BU”.

In order to perform such backup, the control unit 4 has the configuration shown in FIG. FIG. 4 is a functional block diagram showing the configuration of the control unit 4.
As shown in FIG. 4, the control unit 4 includes a backup determination unit 41, a backup request amount calculation unit 42, a backup steam amount calculation unit 43, and a backup instruction unit 44.

The backup determination unit 41 determines whether or not a backup by the second boiler is necessary for the combustion instruction to the first boiler. The first boiler is the boiler 20 that is located at the combustion stop position (−) before the change of the combustion pattern and is located at a combustion position other than the combustion stop position (−) after the change of the combustion pattern. The second boiler is a boiler 20 capable of increasing the amount of steam according to the combustion instruction. When there are a plurality of the boilers 20, the combustion position is basically low, and the boiler with high priority. 20 corresponds.
The determination by the backup determination unit 41 may be performed by an arbitrary method. As an example, the backup determination unit 41 changes the first boiler to a combustion position other than the combustion stop position (−), and then the first boiler when the internal pressure of the steam header 6 does not increase even after a predetermined time has elapsed. On the other hand, it is determined that the backup by the second boiler is necessary. As another example, the combustion position of the boiler 20 is acquired from the local control unit 22, and it is determined whether a backup for the first boiler is necessary according to the time when the boiler 20 was located at the combustion stop position (−). It is good as well. That is, when the first boiler is located at the combustion stop position (−) for a certain time or longer, the backup determination unit 41 determines that the backup by the second boiler is necessary.

The backup request amount calculation unit 42 calculates the steam amount instructed to the first boiler as the backup request amount. Further, the backup steam amount calculation unit 43 calculates a steam amount that increases when the combustion position of the second boiler is increased by one step as the backup steam amount.
In the three-position control boiler 20, backup is possible when the first boiler is instructed to be positioned from the combustion stop position (-) to the low combustion position (L). The backup request amount is 200 kg / h. Similarly, since the second boiler is backed up by being located at the high combustion position (H) from the state where it was located at the low combustion position (L), in this embodiment, the backup steam amount is 600 kg / h.

The backup instruction unit 44 issues a backup instruction to the second boiler when it is determined that backup by the second boiler is necessary. At this time, when the backup steam amount is larger than the backup request amount, if the backup by the second boiler is immediately performed, the steam amount becomes excessive.
Conventionally, only the backup request amount and the backup steam amount are compared, and backup is performed when the backup request amount reaches the backup steam amount. In other words, if the backup request amount for one unit is less than the backup steam amount, the system waits until there are a plurality of first boilers requesting backup, and the backup request amounts of the plurality of first boilers reach the backup steam amount. It was supposed to back up at the timing.

ここで、指示蒸気量とは、燃焼パターンが指示する燃焼位置に応じてボイラ群２から出力されることが期待される蒸気量である。図３を参照して、燃焼パターンＤである場合には、３台のボイラ２０を低燃焼位置（Ｌ）に位置するように指示することから、指示蒸気量は６００ｋｇ／ｈ（＝２００ｋｇ／ｈ×３台）となる。なお、冷却状態にあるボイラ２０は、燃焼停止位置（−）から低燃焼位置（Ｌ）に位置するように制御されても直ちに給蒸できないことから、指示蒸気量は、ボイラ群２から実際に出力されている出力蒸気量と異なることがある。このとき、給蒸できないボイラ２０（第１ボイラ）に対して指示された蒸気量は、バックアップ要求量として算出されることから、出力蒸気量、指示蒸気量及びバックアップ要求量には、「出力蒸気量＝指示蒸気量−バックアップ要求量」の関係が成り立つといえる。 In this regard, in this embodiment, the backup instruction unit 44 enables backup at a more appropriate timing by comparing not only the backup request amount and the backup steam amount but also the necessary steam amount. Specifically, the backup instruction unit 44 issues a backup instruction to the second boiler on condition that the following expression 1 is satisfied.

Here, the command steam amount is a steam amount expected to be output from the boiler group 2 in accordance with the combustion position indicated by the combustion pattern. Referring to FIG. 3, in the case of combustion pattern D, since the three boilers 20 are instructed to be positioned at the low combustion position (L), the indicated steam amount is 600 kg / h (= 200 kg / h). × 3). The boiler 20 in the cooled state cannot be immediately steamed even if it is controlled to be positioned from the combustion stop position (−) to the low combustion position (L). The output steam volume may be different. At this time, the amount of steam instructed to the boiler 20 (first boiler) that cannot supply steam is calculated as the requested backup amount. Therefore, the output steam amount, the indicated steam amount, and the requested backup amount include “output steam”. It can be said that the relationship of “amount = indicated steam amount−required backup amount” is satisfied.

  The detailed configuration of the control unit 4 for performing backup for the first boiler has been described above. Next, the flow of backup by the control unit 4 will be described in detail with reference to FIGS. 3 and 5. FIG. 5 is an operation outline diagram showing the operation at the time of backup. In addition, (1)-(5) shown in FIG.3 and FIG.5 shows the corresponding timing, respectively. 3 and 5, it is assumed that the No. 1 and No. 2 boilers are boilers 20 that can be immediately steamed, and the No. 3 boiler is a cooled boiler 20 that cannot be steamed immediately.

  3 and 5A, at timing (1), a steam amount of 400 kg / h is calculated as a required steam amount from the pressure inside the steam header 6, and the control unit 4 performs the boiler group 2 is instructed to burn in the combustion pattern C. With reference to FIG. 5B, this instruction causes the No. 1 boiler and No. 2 boiler to burn at the low combustion position (L), and the No. 3 boiler is located at the combustion stop position (−).

Thereafter, when the required load increases, the pressure inside the steam header 6 decreases, and as a result, the required steam amount increases to 600 kg / h at the timing (2). At this timing (2), as shown in FIG. 3, the control unit 4 instructs the boiler group 2 to burn in the combustion pattern D.
In the combustion pattern D, in addition to the No. 1 and No. 2 boilers, the No. 3 boiler also burns at the low combustion position (L), but the No. 3 boiler cannot be steamed immediately after being cooled. As shown in A), the control unit 4 determines that the backup is necessary, and calculates 200 kg / h corresponding to the low combustion position (L) as the requested backup amount. Further, the control unit 4 selects the No. 1 boiler as the backup-destination boiler 20 and calculates the amount of steam (600 kg / h) that increases when the combustion position of the No. 1 boiler is increased by one step as the backup steam amount.
At this time, “backup steam amount−requested backup amount”, that is, the second difference is 400 kg / h, whereas “required steam amount−indicated steam amount”, that is, the first difference is 0 kg / h. Does not satisfy 1. In such a case, if the backup by the No. 1 boiler is performed, the output becomes excessive. Therefore, as shown in FIG. 5B, the control unit 4 does not perform the backup at the timing (2). The No. 1 boiler is maintained at the low combustion position (L).

On the other hand, since steam is not supplied from the No. 3 boiler to the steam header 6, the pressure inside the steam header 6 decreases, and as a result, the required steam amount increases to 1000 kg / h at the timing (3). Referring to FIG. 3, the necessary steam amount (1000 kg / h) corresponds to the steam pressure zone d, and therefore, at the timing (3), the control unit 4 performs the combustion pattern with respect to the boiler group 2 similarly to the timing (2). D is instructed to burn.
By the way, since the indicated steam amount of the combustion pattern D is 600 kg / h, “required steam amount−indicated steam amount (first difference)” becomes 400 kg / h, and “backup steam amount−required backup amount (second Difference) ”and the above equation 1 is satisfied. Therefore, as shown in FIG. 5 (B), at timing (3), the control unit 4 gives a backup instruction to the No. 1 boiler and raises the combustion position of the No. 1 boiler one step further at the high combustion position (H). Burn.

Thereafter, when the required load increases, the pressure inside the steam header 6 decreases, and as a result, at the timing (4), the necessary steam amount increases to 1200 kg / h. At this timing (4), as shown in FIG. 3, the control unit 4 instructs the boiler group 2 to burn in the combustion pattern E.
In the combustion pattern E, the No. 1 boiler is burned at the high combustion position (H), but at the timing (3), it is already burned at the high combustion position (H) as a backup of the No. 3 boiler. Therefore, the control unit 4 is changed so that the backup of the No. 3 boiler is performed by the No. 2 boiler, and the steam amount (600 kg / h) that increases when the combustion position of the No. 2 boiler is increased by one step is used as the backup steam amount. calculate.
On the other hand, since the indicated steam amount of the combustion pattern E is 1200 kg / h, “required steam amount−indicated steam amount” is 0 kg / h, which does not satisfy the above formula 1. Therefore, as shown in FIG. 5B, the control unit 4 does not perform backup at the timing (4) and maintains the No. 2 boiler at the low combustion position (L).

  Thereafter, when the pressure inside the steam header 6 decreases and the timing (5) is reached, the required steam volume increases to 1600 kg / h, so that “required steam volume−indicated steam volume (first difference)” is 400 kg / hr. h, which is equal to “backup steam amount−backup request amount (second difference)”, and satisfies the above-mentioned expression 1. Therefore, the control unit 4 gives a backup instruction to the No. 2 boiler, and raises the combustion position of the No. 2 boiler by one step and burns it at the high combustion position (H).

  According to such an operation, the backup by the No. 1 boiler is not immediately performed at the timing (2) when the backup to the No. 3 boiler becomes necessary, and then the internal pressure of the steam header 6 decreases and the backup is performed. Therefore, after waiting until the timing (3) when the required steam amount and the output steam amount are balanced, backup is performed by the No. 1 boiler. Thereby, it is possible to prevent the amount of steam output from the boiler group 2 from being excessive due to backup, and it is possible to suppress overshoot and hunting during backup.

  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.

なお、式２，３におけるα、Ｋは任意の値であり、αは正又は負の値が適宜設定され、Ｋは１以上又は１未満の正の値が適宜設定される。このような重み付けを行うことで、バックアップのタイミングの微調整を行うことができ、ボイラシステム１の応答速度に応じたバックアップが可能になる。 In the above embodiment, the backup is performed when the above expression 1 is satisfied. However, as shown in the following expressions 2 and 3, it may be determined whether to perform the backup by performing a predetermined weighting.

In Expressions 2 and 3, α and K are arbitrary values, α is appropriately set to a positive or negative value, and K is appropriately set to a positive value of 1 or more or less than 1. By performing such weighting, the backup timing can be finely adjusted, and backup according to the response speed of the boiler system 1 becomes possible.

Moreover, in the said embodiment, although this invention was applied to the boiler system provided with the boiler group 2 which consists of the three boilers 20, it is not restricted to this. That is, the present invention may be applied to a boiler system including a boiler group including four or more boilers, or may be applied to a boiler system including a boiler group including two boilers.
Moreover, in the said embodiment, although it is supposed that all the three boilers 20 are comprised with the same boiler (3 position boiler whose low combustion position is 25% of load factors), it is not restricted to this, The boiler 20 The load factor corresponding to the combustion position may be different every time. Similarly, the capacity of the boiler 20 may be different for each boiler 20. Even in such a configuration, it is possible to prevent the amount of steam from becoming excessive by determining whether or not to perform backup according to the above formulas 1 to 3.

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

(1) In the boiler system 1 of this embodiment, the control part 4 is calculated from required steam quantity-instruction | command steam quantity, when the backup by a 2nd boiler is required with respect to the combustion instruction | indication to a 1st boiler. A configuration in which the first difference is compared with the second difference calculated from the backup steam amount-the requested backup amount, and the backup instruction is given to the second boiler on condition that the first difference exceeds the second difference. did.
According to such a configuration, since the required steam volume is directly referred to, an excessive steam volume exceeding the required steam volume is not generated by the backup, and the backup is performed at a timing when the required steam volume and the output steam volume are balanced. It can be performed. As a result, overshoot and hunting during backup can be suppressed, and pressure stability can be improved.

(2) When the backup is required, the control unit 4 is configured to issue a backup instruction to the second boiler on condition that the difference between the first difference and the second difference exceeds a predetermined value.
According to such a configuration, the backup can be performed not at a timing at which the required steam amount and the output steam amount completely coincide, but at a timing finely adjusted with respect to the timing. As a result, backup can be performed at an appropriate timing in consideration of information unique to the boiler system, such as response speed, and pressure stability can be improved.

DESCRIPTION OF SYMBOLS 1 Boiler system 2 Boiler group 20 Boiler 4 Control part 41 Backup determination part 42 Backup demand amount calculation part 43 Backup steam quantity calculation part 44 Backup instruction | indication part

Claims (2)

A boiler system including a boiler group including a plurality of boilers capable of increasing or decreasing a combustion amount in stages according to a selected combustion position, and a control unit that controls a combustion state of the boiler group according to a required load. And
The controller is
A backup determination unit that determines whether or not a backup by the second boiler is necessary for the combustion instruction to the first boiler;
A backup request amount calculation unit that calculates a steam amount corresponding to a combustion instruction to the first boiler as a backup request amount;
A backup steam amount calculation unit that calculates the amount of steam that increases when the combustion position of the second boiler is increased by one step as a backup steam amount;
A first difference that is a difference between a required steam amount corresponding to the required load and an instruction steam amount that is currently instructing output to the boiler group when the backup determination unit determines that a backup is necessary. A backup instruction unit that issues a backup instruction to the second boiler on the condition that the difference exceeds a second difference that is a difference between the backup steam amount and the backup request amount;
Boiler system equipped with. When the backup determination unit determines that the backup is necessary, the backup instruction unit sets the second boiler on the condition that a difference between the first difference and the second difference exceeds a predetermined value. Instruct backup to the
The boiler system according to claim 1.

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