JP2015190664A - boiler system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boiler system capable of keeping a pressure stability when there is present a boiler started to supply steam.SOLUTION: This invention relates to a boiler system 1 including a boiler group 2 having a plurality of boilers 20 and a control part 4. The control part 4 comprises a steam generating instruction part 42 for instructing to start supplying of steam to a boiler 20 in the plurality of boilers 20 not supplying steam in response to a required load; a first determination part 46 for determining whether or not the boiler 20 starts to supply steam through the steam generating instruction part 42; a second determination part 44 for determining whether or not a first time elapses after determination by the first determination part 46 that the boiler 20 started to supply steam; and an output control part 45 for performing a controlling operation for outputting steam of object amount of steam corresponding to the required load by changing the output steam amount of the steam supplying boiler 20 acting as a boiler for supplying steam in the plurality of boilers 20.

Description

  The present invention relates to a boiler system.

2. Description of the Related Art Conventionally, as a boiler system that generates steam by burning a plurality of boilers, a so-called proportional control type boiler system that controls the generation amount of steam by continuously increasing or decreasing the combustion amount of the boiler has been proposed.
In such a boiler system, when the combustion amount is increased so that the load on the steaming boiler (hereinafter also referred to as “steaming boiler”) is uniform, the combustion rate of each boiler is the highest. When the combustion amount is preferentially increased for a low boiler and the combustion amount is decreased, control is performed to preferentially decrease the combustion amount for a boiler having the highest combustion rate of each boiler. By doing so, the combustion rates of the steaming boilers are finally almost the same.

  For example, in Patent Document 1, a boiler is divided into a number increase load zone (for example, a combustion rate of 80% or more), an optimum operation load zone (for example, a combustion rate of 50% to 80%) and a number decrease load zone (for example, a combustion rate of less than 50%). ) When the boiler is burning in the load zone, the number of boilers to be burned is increased, and when the boiler is burning in the load reduction zone, the number of boilers to be burned Proportional control boiler control methods have been proposed. And in the control method of the proportional control boiler proposed by this patent document 1, after performing increase / decrease in the number of the boilers to burn, all the boilers which are burned are operated with a uniform combustion rate.

Japanese Patent Laid-Open No. 11-132405

By the way, when increasing the number of boilers to be burned, the number control device (control unit) issues a steaming instruction for starting steaming to a boiler that is not steaming among a plurality of boilers.
Here, examples of the boiler that is not steamed include a boiler in a combustion stopped state and a boiler in a continuous pilot combustion state (a state of seed fire). When a boiler in a combustion-stopped state receives a steaming instruction to start steaming, it performs pre-purge to remove unburned components of fuel remaining inside the boiler, and after pre-purge is completed, burns the fuel. Start steam generation. On the other hand, when the boiler in the continuous pilot combustion state (seed fire state) receives a steaming instruction to start steaming, it starts combustion and starts generating steam without pre-purging.
In any case, a boiler that has received a steaming instruction for the start of steaming (hereinafter also referred to as an “increase boiler”) usually starts combustion at a minimum combustion rate, for example, 20%. For this reason, when increasing the combustion amount, the number control device (control unit) preferentially increases the combustion amount of the boiler with the lowest combustion rate of each boiler so that the load on the boiler during steaming becomes uniform When the conventional control is performed, when there is a boiler that has started steaming in the boiler group, only the boiler has an extremely low combustion rate, so the combustion amount is concentrated on the boiler. Will increase.

  Also in the method proposed in Patent Document 1, the number of boilers is controlled in the optimum operating load range of each boiler so that each operating boiler is equally loaded. Therefore, when the boiler which started steaming exists, it will concentrate on the boiler which started steaming and will increase a combustion amount.

  However, boilers that have received a steaming instruction (canned boilers) have a delay time from when the fuel is burned until the steam is actually generated, so the boilers that have not yet been steamed Regardless, the control unit may erroneously determine that the can boiler has started steaming. In addition, due to boiler characteristics and equipment issues, the increase in output steam volume may not be stable immediately after the start of steaming for boilers with increased capacity. For example, the upper limit of steam volume that can be increased per unit time of the boiler. Although the maximum increase steam amount which is a value is instructed, the actual output steam amount of the boiler may be smaller than the instruction steam amount. As a result, there is a risk that the boiler system may decrease in pressure due to a shortage of the output steam amount of the increased boiler that has started steaming.

  Therefore, when the number control device (control unit) increases the output steam amount, the boiler output steam amount with the lowest combustion rate of each boiler is given priority so that the load on the boiler during steaming becomes uniform. When the conventional control of increasing is performed, the maximum value that is the upper limit of the amount of steam that can be increased per unit time of the boiler immediately after the start of steaming for the boiler whose unit control device (control unit) has started steaming As a result, there is a problem in that the boiler system reaches a pressure drop due to a shortage of the output steam amount of the boiler that has started steam supply.

  The present invention determines whether or not the boiler has started steaming when a steaming instruction for steaming start is given by the steaming instruction unit to a boiler that is not steaming among a plurality of boilers And a second determination unit that determines whether or not a first time has elapsed since it was determined by the first determination unit that steaming has started. By doing so, the number control device (control unit) can appropriately control the increase in the combustion amount of the boiler immediately after the start of steaming, and by doing so, can suppress the pressure drop of the boiler system and maintain the pressure stability. The purpose is to provide a boiler system.

  The present invention is composed of a plurality of boilers that can burn by changing the combustion rate, to generate steam of a target steam amount according to the required load from the load group and the boiler group that supplies steam to the load equipment, And a control unit that controls a combustion state of the boiler group, wherein the control unit starts steaming a boiler that is not steamed among the plurality of boilers according to a required load. A steaming instruction unit that performs steaming instructions for the steam, a first determination unit that determines whether or not the boiler that has been steamed by the steaming instruction unit has started steaming, and the first determination unit A second determination unit that determines whether or not a first time has elapsed since it was determined that the boiler that has been instructed to steam has started steaming; The steam output from the steam supply boiler is the required load. Flip By modified, an output control unit for performing control to output the target amount of steam vapor in accordance with the required load, to a boiler system comprising a.

  The output control unit determines an increase in the output steam amount per unit time of the steaming start boiler determined by the first determination unit to start steaming, and the second determination unit passes the first time. Until it is determined that it has been, it is preferable to suppress it to less than the maximum increase steam amount preset as the upper limit value of the steam amount that can be increased per unit time of the boiler.

  Increase in the amount of steam output per unit time of the steaming start boiler determined by the first determination unit to start steaming until it is determined by the second determination unit that the first time has elapsed The amount is preferably equal to or less than a preset first increase amount.

  The first increase amount may be a unit steam amount of the steam supply start boiler.

  The first increase amount may be 1% or less of the maximum steam amount of the steam supply start boiler.

  The first increase amount can be zero.

  According to the boiler system of the present invention, when a steaming instruction is given by a steaming instruction unit to start steaming, a boiler that has not steamed first determines whether or not the boiler has started steaming. By determining by the determination unit and determining by the second determination unit whether or not the first time has elapsed since the first determination unit determined that the boiler has started steaming, the number control device (control unit) ) Can appropriately control the increase in the combustion amount of the boiler immediately after the start of steaming. For this reason, the deviation of the instruction | indication steam volume and output steam volume in the whole system | strain of a boiler group can be suppressed to the minimum, the pressure drop of a boiler system can be suppressed, and pressure stability can be maintained.

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 functional block diagram which shows the structure of a control part. It is a flowchart which shows operation | movement of a boiler system. It is a figure which shows an example of the combustion state of a boiler group.

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 of the present invention will be described with reference to FIG. The boiler system 1 includes a boiler group 2 including a plurality of (five) boilers 20, a steam header 6 that collects steam generated in the plurality of boilers 20, and steam that measures the pressure inside the steam header 6. A pressure sensor 7 and a number control device 3 having a controller 4 that controls the combustion state of the boiler group 2 are provided.

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 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 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 state of each boiler 20 which comprises the boiler group 2. FIG.

  Specifically, if the required load (steam consumption) increases due to an increase in demand for the steam use facility 18 and the amount of steam supplied to the steam header 6 (output steam amount described later) is insufficient, the steam header 6 The internal vapor pressure will decrease. On the other hand, if the demand load (steam consumption) decreases due to a decrease in the demand for the steam use facility 18 and the amount of steam supplied to the steam header 6 becomes excessive, the steam pressure inside the steam header 6 increases. Become. 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 a necessary steam amount that is a steam amount required according to the consumed steam amount (required load) of the steam using facility 18 based on the steam pressure of 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 the boiler group 2 according to the present embodiment.
The boiler 20 of the present embodiment is composed of a proportional control boiler capable of burning by continuously changing the combustion rate.
The proportional control boiler is a boiler whose combustion rate can be continuously controlled at least in the range from the minimum combustion state S1 (for example, a combustion state with a combustion rate of 20%) to the maximum combustion state S2. The proportional control boiler adjusts the combustion rate, for example, by controlling the opening degree (combustion ratio) of a valve that supplies fuel to the burner and a valve that supplies combustion air.

  Also, the continuous control of the combustion rate means that the calculation or signal in the local control unit 22 described later is a digital method and is handled in stages (for example, the output (combustion rate) of the boiler 20 is in increments of 1%). Even when the output is controlled).

In this embodiment, the change of the combustion state between the combustion stop state S0 and the minimum combustion state S1 of the boiler 20 is controlled by turning on / off the combustion of the boiler 20 (burner). In the range from the minimum combustion state S1 to the maximum combustion state S2, the combustion rate can be continuously controlled.
More specifically, a unit steam amount U, which is a unit of variable steam amount, is set for each of the plurality of boilers 20. Thus, the boiler 20 can change the steam amount in units of the unit steam amount U in the range from the minimum combustion state S1 to the maximum combustion state S2.

The unit steam amount U can be appropriately set according to the steam amount (maximum steam amount) in the maximum combustion state S2 of the boiler 20, but from the viewpoint of improving the followability of the output steam amount to the necessary steam amount in the boiler system 1. It is preferably set to 0.1% to 20% of the maximum steam amount of 20, and more preferably set to 1% to 10%.
Note that the output steam amount indicates the steam amount output by the boiler group 2, and this output steam amount is represented by the total value of the steam amounts output from each of the plurality of boilers 20.

Each of the plurality of boilers 20 is set with a maximum fluctuation steam amount that is an upper limit value of the steam amount that can fluctuate per unit time. In the present embodiment, the maximum fluctuation steam amount is set as an upper limit value of the steam amount that can be changed in one second. Further, the maximum fluctuating steam amount is set to a value corresponding to an integral multiple of the unit steam amount U (for example, unit steam amount × 1).
The maximum variable steam volume is set to the maximum increase steam volume that is the upper limit of the steam volume that can be increased per unit time and the maximum decrease steam volume that is the upper limit of the steam volume that can be decreased per unit time. The
In addition, as a setting of the maximum fluctuation steam amount, instead of a value corresponding to an integral multiple of the unit steam amount U (for example, unit steam amount × 1), a ratio (for example, a percentage by percentage) with respect to the maximum steam amount of the boiler 20 is set. It may be used. Moreover, you may set the combustion rate which outputs the maximum fluctuation | variation steam amount of the boiler 20. FIG.

  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, a combustion stop instruction, or the like. 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 “5” are assigned to the first to fifth units of the boiler 20, the first unit has the highest priority, and the fifth unit has the highest priority. Lowest. In the normal case, this priority order is changed at predetermined time intervals (for example, 24 hour intervals) under the control of the control unit 4 described later.

  The boiler group 2 is set with a reference threshold for determining the number of steam supply boilers. In the present embodiment, the reference steam amount is used as the reference threshold value.

For example, when the required steam amount reaches a predetermined reference steam amount (more or larger), combustion of the boiler 20 that is not steamed (in a combustion stop state or a continuous pilot combustion state) is started, and the number of boilers 20 is increased. To increase.
Further, when the required steam amount reaches a preset reference steam amount (below or becomes smaller), one of the steam supply boilers 20 is brought into a combustion stopped state or a continuous pilot combustion state.
These predetermined reference steam amounts can be arbitrarily set, and arbitrary information other than the reference steam amount may be used as a reference threshold for determining the number of steam supply boilers.

For example, the reference threshold value may be the combustion rate of the steam supply boiler 20.
When the combustion rate is used, the combustion rate of the steam supply boiler 20 is a predetermined reference threshold (for example, 50% when there is one steam supply boiler 20, 100% when there are two steam boilers, 150% when there are three, etc.) ), The boiler 20 that has not been steamed starts to burn, and the number of steamed boilers 20 is increased.
On the contrary, the combustion rate of the steam supply boiler 20 is a predetermined reference threshold (for example, 50% when there are two boilers 20 in the combustion state, 100% when three boilers, 150% when four boilers, etc.) Is reached, the steam supply boiler 20 is put into a combustion stopped state or a continuous pilot combustion state, and the number of steam supply boilers 20 is reduced.

The above boiler 20 is provided with the boiler main body 21 in which combustion is performed, and the local control part 22 which controls the combustion state of the boiler 20, as shown in FIG.
The local control unit 22 changes the combustion state of the boiler 20 according to the required load. Specifically, the local control unit 22 controls the combustion state 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 an actual combustion state 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 necessary steam amount of the boiler group 2 according to the required load and the combustion state of each boiler 20 corresponding to the required steam amount based on the steam pressure signal from the steam pressure sensor 7, The number control signal is transmitted to the boiler 20 (local control unit 22). 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 state received from each boiler 20, and combustion patterns of a plurality of boilers 20. Information on the setting conditions, information on the setting related to the reference threshold for determining the number of steam supply boilers, information on the unit steam amount U of each boiler 20, information on the maximum variable steam amount of each boiler 20, a plurality of Information on setting the priority order of the boiler 20, information on setting related to the change (rotation) of the priority order, and the like are stored. The unit steam amount U and the maximum fluctuating steam amount (maximum increasing steam amount and maximum decreasing steam amount) may be different for each boiler.

  In addition, as will be described later, the storage unit 5 stores setting information (a first time, a first increase amount, and the like) related to the amount of steam that can be increased per unit time immediately after the start of steaming of each boiler 20. For example, the first increase amount may be an integral multiple of the unit steam amount U of each boiler 20 (for example, unit steam amount U × 2). In particular, the first increase amount may be the unit steam amount U of each boiler 20. Further, the first increase amount may be 1% or less of the maximum steam amount of each boiler 20. Further, the first increase amount may be set to zero, that is, the output steam amount may not be increased.

  The control unit 4 gives various instructions to the boilers 20 through the signal lines 16 and receives various data from the boilers 20 to control the combustion states and priority levels of the plurality of boilers 20. When each boiler 20 receives a signal for changing the combustion state from the number control device 3, it controls the boiler 20 according to the instruction.

  Here, when the consumed steam amount (required load) of the steam using facility 18 increases and the required steam amount reaches a predetermined reference steam amount set in advance, the control unit 4 enters the combustion stop state S0 or the continuous pilot combustion state. The combustion of a certain boiler 20 is started, and the number of steam supply boilers 20 is increased.

  Boilers that have started steaming may not be stable immediately after the start of steaming due to boiler characteristics or equipment problems. Although the maximum increase steam amount that is the upper limit value of the steam amount is instructed, the actual output steam amount of the boiler may become smaller than the instruction steam amount.

  Therefore, when there is a boiler that has started steaming, the control unit 4 per unit time of the boiler until it is determined that the first time has elapsed since the boiler started steaming. By using the first increase amount instead of the maximum increase steam amount that is the upper limit of the steam amount that can be increased, the increase in the output steam amount per unit time of the boiler is suppressed, and the boiler other than the boiler that has started steaming Let other steam boilers share the remaining increase in output steam. In addition, “until it is determined that the first time has passed since the boiler started steaming” means “the first time after the boiler started steaming and incorporated in the unit control”. It is good also as "until it determines with having passed."

  In order to realize the above functions, the control unit 4 includes a steam amount calculation unit 41, a steaming instruction unit 42, a first determination unit 43, a second determination unit 44, and an output control unit 45. .

  The steam amount calculation unit 41 calculates the necessary steam amount according to the required load based on the steam pressure of the steam header 6.

When the steam consumption (required load) of the steam using facility 18 increases and reaches a reference threshold value set in advance (or larger or larger), the steaming instruction unit 42 enters the combustion stop state S0 or the continuous pilot combustion state. A steaming instruction for starting steam supply (steaming) to a certain boiler 20 is performed.
Here, the steaming instruction for the boiler 20 in the combustion stop state S0 is, for example, by a pilot operation instruction for igniting the pilot burner and operating the blower to remove the combustible components accumulated in the boiler 20 and the main burner. Includes combustion instructions. Further, the steaming instruction for the boiler 20 in the continuous pilot combustion state includes a combustion instruction by the main burner.
The control unit 4 stores, in the storage unit 5, information indicating that the steaming instruction has been issued with respect to the boiler (boost boiler) 20 that has received the steaming instruction.

In addition, after the steaming instruction | indication part 42 gives steaming instruction | indication, the control part 4 burns the boiler increase boiler 20 by the maximum combustion rate (100%) until the pressure of the steam generated from the boiler increase boiler 20 begins to rise. May be. Here, until the pressure of the generated steam begins to increase, for example, the steam pressure of the steam generated from the can boiler 20 may increase to a predetermined pressure, and the water tube temperature of the boiler 20 is predetermined. It may be until the temperature is exceeded, or may be until a predetermined time elapses after starting combustion at the maximum combustion rate. By carrying out like this, the can water of the increase boiler 20 can be boiled quickly, and the time taken until the increase boiler 20 generate | occur | produces a steam can be reduced.
And after the pressure of the vapor | steam generate | occur | produced from the can boiler 20 begins to rise, the control part 4 is the minimum combustion rate (20%) until it determines with the said boiler 20 starting steaming by the 1st determination part 43. Thus, the boiler 20 may be burned.

  The 1st determination part 43 determines whether the can boiler 20 started steaming. Here, the determination of the steam supply start can be made based on the steam pressure generated from the booster boiler 20. As an example, when the steam pressure generated from the boiler 20 becomes higher than the steam pressure of the steam header 6 by the pressure loss of the steam pipe 11, the first determination unit 43 determines that the can boiler 30 has started steaming. be able to. The first determination unit 43 determines that the steam pressure generated from the booster boiler 20 is higher than the steam pressure of the steam header 6 by the pressure loss of the steam pipe 11, and the timer (not shown) detects the burner. You may determine with the increase boiler 20 having started steam supply by measuring that predetermined time passed since ignition.

  Also, such a determination of the start of steaming may be performed not by the control unit 4 of the number control device 3 but by the local control unit 22 of the can boiler 20. When the local control unit 22 determines the start of steaming, the control unit 4 (first determination unit 43) determines the start of steaming of the can boiler 20 by receiving a predetermined notification from the local control unit 22. That is, when the local control unit 22 determines that the steam increase boiler 20 has started steaming, the local control unit 22 notifies the unit control device 3 that steaming has started, whereby the control unit 4 (first The determination unit 43) determines whether or not to start the steaming of the booster boiler 20.

  At this time, the control unit 4 may correct the upper limit value of the steam amount that can be increased per unit time of the can boiler 20 to the first increase amount instead of the preset maximum increase steam amount. By carrying out like this, until the 1st time passes after the boiler increase boiler 20 starts steaming (or 1st time after the boiler increaser 20 starts steaming and it is integrated in unit control) The increase in the output steam volume per unit time of the increase boiler 20 is suppressed, and by doing so, other steam supply boilers other than the increase boiler 20 share the remaining increase in the output steam volume. Can do.

  The second determination unit 44 determines that the boiler 20 has started steaming by the first determination unit 43 (or the first determination unit 43 determines that the boiler 20 has started steaming, and the output control unit 45. Then, the time counting unit determines whether or not the first time, for example, 20 seconds has elapsed. And after progress of 1st time, the control part 4 returns the upper limit of the vapor | steam amount which can be increased per unit time of the can boiler 20 from the 1st increase amount to the original maximum increase steam amount. By carrying out like this, after progress of 1st time, the number control apparatus 3 (control part 4) is the increase of the preset maximum increase steam amount with respect to the can boiler 20 similarly to other steam supply boilers. Can be instructed. The first time can be appropriately set according to the characteristics of the boiler.

The output control unit 45 temporarily increases the required load (steam consumption) due to an increase in demand of the steam using equipment 18 until the second determination unit 44 determines that a first time, for example, 20 seconds has elapsed. In this case, the increase in the output steam amount instructed to the can boiler 20 is suppressed so as not to exceed the first increase amount. As a result, the remaining amount of deviation, which is obtained by subtracting the increase in the output steam amount instructed to the booster boiler 20 from the deviation amount between the required steam amount and the output steam amount, is shared by the steam supply boilers 20 other than the booster boiler 20. Will be controlled.
As described above, the first increase amount may be, for example, an integral multiple of the unit steam amount U of the can boiler 20 (for example, unit steam amount U × 2). The first increase amount may be, for example, the unit steam amount U of the can boiler 20. Further, the first increase amount may be 1% or less of the maximum steam amount of the can boiler 20. Further, the first increase amount is zero, that is, the output control unit 45 is zero until the second determination unit 44 determines that the first time has elapsed by determining the increase amount of the output steam amount of the can boiler 20. It is good.

  Thereafter, when the second determination unit 44 determines that the first time, for example, 20 seconds has elapsed, as described above, the upper limit value of the amount of steam that can be increased per unit time of the can boiler 20 is the first value. The increased amount is returned to the original maximum increased steam amount. By doing so, the output control unit 45 continuously changes the output steam amount of the steam supply boilers 20 including the booster boiler 20 according to the required load, so that the target steam amount according to the required load is obtained. The control for outputting the steam is performed.

  In the present embodiment, the above control is performed at predetermined unit time intervals (for example, every second).

  According to the control unit 4 configured as described above, even when there is a boiler that has started steaming, steaming is started when the output steam amount is increased due to an increase in demand for the steam-using facility 18. Until the first time elapses, the steam supply boiler other than the boiler can share the increase in the output steam amount, and the difference between the instruction steam amount by the control unit 4 and the output steam amount of the boiler group is minimized. By staying at, pressure drop in the boiler system 1 can be suppressed and pressure stability can be maintained.

  Next, in the boiler system 1 of this embodiment, the operation when the required load (steam consumption) increases due to an increase in demand for the steam using facility 18 will be described with reference to FIG. FIG. 4 shows an operation in a period from when the boiler 20 in the combustion stop state S0 of the boiler system 1 according to the present embodiment receives a steaming instruction to start steaming and to pass a first time after steaming is started. It is a flowchart which shows.

  In step ST1, when the amount of steam consumed (required load) of the steam using equipment 18 increases and reaches a preset reference threshold value (more or more), the steaming instruction unit 42 is in the combustion stop state S0 or continuous. A steaming instruction is given to the boiler 20 in the pilot combustion state.

  In step ST <b> 2, the output control unit 45 performs backup control by the steam supply boiler until the boiler (boost boiler) 20 that has received the steaming instruction starts steaming.

  In step ST3, the 1st determination part 43 determines whether the can increase boiler 20 started the steam supply. When it determines with the can boiler 20 having started steaming (Yes), it progresses to step ST4. When it determines with the can boiler 20 not having started steaming (No), it returns to step ST2.

  In step ST4, the control unit 4 corrects the upper limit value of the amount of steam that can be increased per unit time of the can boiler 20 to the first increase amount instead of the maximum increase steam amount, and the output control unit 45 20 is incorporated into unit control. In addition, the output steam amount of the other steam supply boilers 20 is decreased by the amount of steam output from the can boiler 20 that has become steamable.

  In step ST5, when the required load increases, the output control unit 45 suppresses the increase in the output steam amount per unit time of the can boiler 20 so that it does not exceed the first increase amount, and other steaming boilers. Control to share the increase in output steam volume. (In addition, when the required load decreases, control is performed so as to decrease the output steam amount of other steam supply boilers.)

  In step ST6, the second determination unit 44 determines whether or not a first time (for example, 20 seconds) has elapsed since the can boiler 20 started steaming and was incorporated in the unit control. If it is determined that the first time (for example, 20 seconds) has elapsed since the boiler increaser 20 started steaming and was incorporated in the unit control (Yes), the process proceeds to step ST7. When it determines with the 1st time (for example, 20 seconds) not having passed (No), it returns to step ST5.

  In step ST7, the control unit 4 returns the upper limit value of the steam amount that can be increased per unit time of the can boiler 20 from the first increase amount to the original maximum increase steam amount. In this way, after the first time has elapsed, the number control device (control unit) instructs the boiler increaser 20 to increase the preset maximum increase steam amount in the same manner as other steam supply boilers. Will be able to.

  Next, a specific example of the operation of the boiler system 1 of the present embodiment will be described with reference to FIG. Here, as shown in FIG. 5, the boiler system 1 has a boiler group 2 including five boilers 20, and the unit steam amount U of each boiler 20 is set to one scale shown in FIG. 5. ing. The maximum increase steam amount of each boiler 20 is a unit steam amount U × 7. Moreover, the priority of "1"-"5" is assigned to each of No. 1 to No. 5 of the boiler 20. Here, it is assumed that the unit steam amount U of the No. 1 boiler 20 to No. 5 boiler 20 is the same. Further, it is assumed that the unit steam amount U is set as the first increase amount.

  When the consumed steam amount (required load) of the steam use facility 18 increases and the required steam amount reaches the increased reference steam amount, the steaming instruction unit 41 instructs steaming to the boiler 20 in the combustion stopped state S0. In FIG. 5 (1), the steaming instruction | indication part 41 is performing steaming instruction | indication with respect to the No. 3 boiler among No. 3 boiler-No. 5 boiler of combustion stop state S0. Although the No. 3 boiler is assumed to be in the combustion stop state S0, it may be assumed to be a continuous pilot combustion state.

When the No. 3 boiler starts combustion based on the steaming instruction, the first determination unit 43 determines whether the No. 3 boiler has started steaming based on the steam pressure of the steam generated from the No. 3 boiler. In FIG. 5 (2), it is assumed that the No. 3 boiler has not yet started steaming.
When the No. 3 boiler that has instructed steaming has not started steaming, the output control unit 45 uses the steam that is scheduled to be generated from the No. 3 boiler instead of the No. 1 and No. 2 boilers that are already in combustion. The combustion rate of the No. 1 boiler and the No. 2 boiler is increased so as to be generated. Further, the output control unit 45 continuously sets the combustion rates of the No. 1 boiler and the No. 2 boiler according to fluctuations in the steam consumption (required load) of the steam using equipment 18 until the No. 3 boiler starts steaming. Change.

  Thereafter, when the No. 3 boiler starts steaming, steam generated from the No. 1 boiler, the No. 2 boiler, and the No. 3 boiler is generated from the boiler group 2. At this time, since the steam generated from the No. 1 boiler and the No. 2 boiler becomes excessive instead of the No. 3 boiler, the output control unit 43 is generated from the No. 3 boiler as shown in FIG. The amount of steam generated from the Unit 1 and Unit 2 boilers is reduced by the amount of steam. That is, the combustion rates of the No. 1 boiler and the No. 2 boiler are reduced by the combustion rate of the No. 3 boiler that has started steaming.

  Unit steam for every unit time (for example, 1 second) in the state until the first time elapses after the No. 3 boiler starts steaming and is incorporated in the unit control (the state shown in FIG. 5 (3)). The operation of the boiler system 1 when there is an increase in the required steam amount corresponding to a deviation amount seven times the amount U (when the required load increases) will be described.

  The operation of the boiler system 1 in the first 1 second will be described. In addition, FIG. 5 (4) is a figure which shows the combustion state of the boiler group 2 when 1 second passes from the state shown in FIG. 5 (3).

  The control unit 4 selects the three boilers 20 in ascending order of combustion rate. In the state shown in FIG. 5 (3), since the combustion rates of the No. 1 boiler 20 and the No. 2 boiler 20 are equal, the control unit 4 performs the No. 3 boiler 20, the No. 1 boilers 20, 2 based on the priority order. The order of the machine boiler 20 is selected.

  Since the first time has not elapsed since the No. 3 boiler 20 starts steaming, the output control unit 45 increases the output steam amount increase per unit time of the No. 3 boiler 20 to the first increase amount ( The amount of increase in the output steam amount (unit steam amount U) instructed to the No. 3 boiler 20 from the deviation amount (unit steam amount U × 7) between the required steam amount and the output steam amount. ) Is subtracted from the No. 1 boiler 20 and the No. 2 boiler 20 so as to share the residual deviation (unit steam amount U × 6).

  As an example, the output control unit 45 controls the unit steam amount U × 3 to be shared by the No. 1 boiler 20 and the No. 2 boiler 20 respectively.

  As a result, as shown in FIG. 5 (4), the output control unit 45 sets the steam amount of the No. 3 boiler 20, the No. 1 boiler 20, and the No. 2 boiler 20 to the unit steam amount U and the unit steam amount, respectively. Increase U × 3 and unit vapor amount U × 3.

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

When increasing the number of boilers to be burned, the number control device 3 gives a steaming instruction to start steaming to the boiler 20 that is not steaming among a plurality of boilers. As a result, the boiler 20 that has received the steaming instruction usually starts combustion at a minimum combustion rate, for example, 20%.
However, since the boiler 20 that has received the steaming instruction may not stabilize the increase in the output steam amount immediately after the start of steaming, for example, the maximum is the upper limit value of the steam amount that can be increased per unit time of the boiler 20. Although the increased steam amount is instructed, the actual output steam amount of the boiler 20 may be smaller than the instructed steam amount.

  That is, when the number control device 3 increases the output steam amount, the output steam amount of the boiler 20 with the lowest combustion rate of each boiler is preferentially increased so that the load of the boiler 20 during steaming becomes uniform. If the conventional control of making it perform is performed, there exists a possibility that a boiler system may lead to a pressure fall by the shortage of the output steam amount of the boiler which started the said steam supply.

Therefore, when the amount of steam consumed (required load) of the steam-using facility 18 increases and reaches a preset reference threshold value (above or becomes larger), the steaming instruction unit 42 is in the combustion stop state S0 or continuous pilot combustion. A steaming instruction is given to the boiler 20 in a state, and the output control unit 45 increases the amount of steam output per unit time of the steaming start boiler 20 determined by the first determination unit 43 to start steaming. The amount is suppressed to less than the maximum increase steam amount set in advance as the upper limit value of the steam amount that can be increased per unit time of the boiler until the second determination unit 44 determines that the first time has passed. Then, control is performed so as to share the increase in the output steam amount with the other steam supply boilers.
The amount of increase in the output steam amount of the steaming start boiler 20 determined to have started steaming by the first determination unit 46 is until the second determination unit 44 determines that the first time has elapsed. It is good also as below the preset 1st increase amount.
At that time, as the first increase amount, for example, the unit steam amount of the steam supply start boiler 20, 1% or less of the maximum steam amount of the steam supply start boiler 20, or zero can be set.

  As a result, the boiler 20 that has received the steaming instruction does not stabilize the increase in the output steam amount immediately after the start of steaming. For example, the maximum increase steam that is the upper limit value of the steam amount that can be increased per unit time of the boiler 20. Even if the amount is instructed, even if the actual output steam amount of the boiler 20 may be less than the instructed steam amount, the first time has elapsed since the boiler 20 started steaming. Until it is determined that it has been performed, the increase in the output steam amount per unit time of the boiler can be suppressed, and the increase in the output steam amount can be shared with other boilers other than the boiler. For this reason, the pressure drop can be suppressed and pressure stability can be maintained by minimizing the deviation between the indicated steam volume and the output steam volume in the entire system of the boiler group.

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 this embodiment, although this invention was applied to the boiler system provided with the boiler group 2 which consists of the five 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 six or more boilers, and may be applied to a boiler system including a boiler group including four or less boilers.

  Further, in the present embodiment, the boiler 20 is controlled by changing the combustion state between the combustion stop state S0 and the minimum combustion state S1 by turning on / off the combustion of the boiler 20, and the maximum combustion from the minimum combustion state S1. In the range of state S2, although comprised with the proportional control boiler 20 which can control an output steam quantity continuously, it is not restricted to this. In other words, the boiler may be constituted by a proportional control boiler that can continuously control the output steam amount in the entire range from the combustion stop state to the maximum combustion state.

  Moreover, in this embodiment, although the boiler group 2 was comprised by the several boiler 20 with the same unit steam amount U, it is not restricted to this. That is, the boiler group may be configured by a plurality of boilers having different unit steam amounts.

DESCRIPTION OF SYMBOLS 1 Boiler system 2 Boiler group 4 Control part 20 Boiler 41 Steam volume calculation part 42 Steaming instruction | indication part 43 1st determination part 44 2nd determination part 45 Output control part

Claims (6)

A plurality of boilers that can burn at different combustion rates, and supply steam to load equipment;
A control unit for controlling the combustion state of the boiler group in order to generate steam of a target steam amount according to a required load from a load device;
A boiler system comprising:
The controller is
Depending on the required load, a steaming instruction unit for instructing steaming to start steaming for a boiler that is not steamed among the plurality of boilers,
A first determination unit that determines whether the boiler instructed to steam by the steaming instruction unit has started steaming;
A second determination unit that determines whether or not a first time has elapsed since it was determined by the first determination unit that the boiler instructed to start steaming;
By changing the output steam amount of the steam supply boiler, which is a boiler supplying steam among the plurality of boilers, according to the required load, control for outputting the steam of the target steam amount according to the required load is performed. An output control unit to perform,
Boiler system equipped with.   The output control unit determines an increase in the output steam amount per unit time of the steaming start boiler determined by the first determination unit to start steaming, and the second determination unit passes the first time. The boiler system according to claim 1, wherein the boiler system is controlled to be less than a maximum increase steam amount set in advance as an upper limit value of a steam amount that can be increased per unit time of the boiler until it is determined that the boiler has been operated.   The increase in the output steam amount per unit time of the steaming start boiler determined by the first determination unit to start steaming until it is determined by the second determination unit that the first time has passed. The boiler system according to claim 2, wherein the amount is equal to or less than a preset first increase amount.   The boiler system according to claim 3, wherein the first increase amount is a unit steam amount of the steam supply start boiler.   The boiler system according to claim 3, wherein the first increase amount is 1% or less of a maximum steam amount of the steam supply start boiler.   The boiler system according to claim 5, wherein the first increase amount is zero.

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