JP6926469B2 - Boiler system - Google Patents

Description

The present invention relates to a boiler system having a boiler group consisting of continuously controlled boilers.

There is a case where a boiler group consisting of continuously controlled boilers capable of continuously changing the combustion rate is used as an auxiliary use of a large-scale boiler system such as a water pipe boiler or as a backup thereof. A large-scale boiler system covers most of the steam output of the steam header, and a continuous control boiler makes up for the shortfall.
In such a case, on the large-scale boiler system side, most of the steam output of the steam header is covered, and the shortage is supplemented by the continuous control boiler. Therefore, in many cases, the large-scale boiler system controls the output steam amount based on the header pressure value, which is the steam pressure inside the steam header. In that case, the continuous control boiler used for the auxiliary application is required to operate so as to maintain a constant output steam amount without performing pressure control.
On the other hand, a group of boilers composed of continuous control boilers is provided with a number control device, and is usually configured to operate so as to control combustion of each continuous control boiler based on a header pressure value (see, for example, Patent Document 1). ).

Japanese Unexamined Patent Publication No. 2014-115070

However, the boiler system consisting of a continuous control boiler and a number control device does not have a function to control the total value of the output steam amount of the boiler group to be a constant value, and the output steam amount is constant as it is. Cannot meet the requirement to maintain.
On the other hand, when maintaining a large-scale boiler system, it is necessary to stop the large-scale boiler system. In that case, the output steam amount is controlled based on the header pressure value in order to back up the required steam amount. The ability to do this is still needed.
Therefore, in addition to the conventional function of controlling the output steam amount based on the header pressure value, if necessary, the total value of the total boiler output steam amount becomes a constant value without pressure control. There is a demand for a continuous control boiler system that can control the amount of steam at a constant rate.

An object of the present invention is to provide a continuously controlled boiler system capable of constantly controlling the output steam amount so that the total value of the total boiler output steam amount not affected by the header pressure becomes a constant value.

The present invention describes a boiler group consisting of one or more boilers capable of continuously changing the combustion rate, a steam header that collects the steam generated in the boiler group, and a combustion state of the boiler group. It is a boiler system including a number control unit to be controlled, and for each of the boilers, an eco-driving zone, which is a range of a combustion rate at which the boiler efficiency becomes higher than a predetermined value, is set for each of the boilers. The number control unit is divided into an output steam amount setting unit that presets a constant output steam amount, which is the amount of steam output by the boiler group, and the boiler group in order to output the constant output steam amount. When the combustion rate is evenly distributed to each of the included boilers, the number of combustion units is calculated so that the combustion rate of each boiler falls within the range of the eco-driving zone, and the number of combustion units is calculated by the unit. The control target boiler setting unit that sets the calculated boilers for the number of burned units as the control target boiler, and the control target boiler set by the control target boiler setting unit so as to generate the steam of the constant output steam amount. The present invention relates to a boiler system including a first control unit for controlling a combustion state of the above.

Further, a boiler pressure measuring means for measuring a boiler pressure value which is a steam pressure inside the boiler, a water supply temperature measuring means for measuring a water supply temperature which is a temperature of water supplied to the boiler main body of the boiler, and the water supply. A combustion rate calculation unit that calculates a combustion rate that outputs a given amount of steam based on the temperature and the boiler pressure value is provided, and the first control unit is further calculated by the combustion rate calculation unit. The combustion state of the controlled boiler may be controlled based on the combustion rate.

Further, the unit for calculating the number of combustion units sets in advance a precondition for the number of combustion units that specifies whether to suppress or make the number of combustion units excessive, and when calculating the number of combustion units, there are a plurality of options or options. If is not present, the number of burned units may be calculated based on the precondition for the number of burned units.

Further, based on the header pressure measuring means for measuring the header pressure value which is the steam pressure inside the steam header, the header pressure range setting unit for presetting the upper limit and the lower limit of the header pressure value, and the header pressure value. A required steam amount calculation unit that calculates the required steam amount, a second control unit that controls the combustion state of the boiler group so as to generate steam of the required steam amount calculated by the required steam amount calculation unit, and the header. When the pressure value exceeds the upper limit or falls below the lower limit, the control of the combustion state of the boiler group by the first control unit is stopped, and the combustion state of the boiler group by the second control unit is stopped. A control switching unit for executing the control of the above may be provided.

Further, the number control unit further includes a priority setting unit for setting and changing the priority of each boiler included in the boiler group, and when the priority setting unit changes the priority of each boiler. , Among the boilers in the combustion stopped state, the boiler having a higher priority may be started to burn.

Further, the number control unit may stop the combustion of the boiler having a lower priority among the boilers in the combustion state when the priority of each boiler is changed by the priority setting unit.

According to the present invention, it is possible to provide a continuously controlled boiler system capable of constantly controlling the output steam amount so that the total value of the total boiler output steam amount not affected by the header pressure becomes a constant value.

It is a figure which shows the outline of the boiler system 1 which concerns on this embodiment. It is a functional block diagram which shows the structure of the control part of this embodiment. It is a figure which shows an example of the processing of the combustion rate calculation part of this embodiment. It is a figure which shows an example of the processing of the combustion rate calculation part of this embodiment. It is a flowchart which shows the operation example of the control part of this embodiment. It is a flowchart which shows the operation example of the control part of this embodiment. It is a flowchart which shows the operation example of the control part of this embodiment.

Hereinafter, preferred embodiments of the boiler system of the present invention will be described with reference to the drawings. The present embodiment is an example, and the technical scope of the present invention is not limited thereto.

[First Embodiment]
First, the overall configuration of the boiler system 1 according to the first embodiment will be described with reference to FIG. As shown in FIG. 1, the boiler system 1 includes, for example, a boiler group 2 composed of five continuously controlled boilers 20, a steam header 6 for collecting steam generated in these plurality of boilers 20, and the steam. A steam pressure sensor 7 for measuring the pressure inside the header 6 and a number control device 3 having a control unit 4 for controlling the combustion state of the boiler group 2 are provided.
Hereinafter, unless otherwise specified, the boiler 20 refers to a continuously controlled boiler.

As shown in FIG. 1, the boiler 20 includes a boiler main body 21 on which combustion is performed, a local control unit 22 that controls the combustion state of the boiler 20, and a water supply temperature that is the temperature of water supplied to the boiler main body of the boiler 20. It is provided with a water supply temperature measuring unit 23 for measuring the above, and a steam pressure sensor 24 as a boiler pressure measuring unit for measuring the boiler pressure which is the steam pressure generated from the boiler 20.

The local control unit 22 controls the combustion state of the boiler 20 based on the control signal transmitted from the number control device 3 via the signal line 16. Further, the local control unit 22 transmits the signal used by 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 state of the boiler 20, the boiler pressure value of the boiler 20, the temperature of the supply water supplied to the boiler main body 21, and other data.

The boiler group 2 generates steam to be supplied to the steam use equipment 18.
The steam header 6 is connected to a plurality of boilers 20 constituting the boiler group 2 via a steam pipe 11. The downstream side of the steam header 6 is connected to the steam use facility 18 via a steam pipe 12.
The steam header 6 adjusts the mutual pressure difference and pressure fluctuation of the plurality of boilers 20 by collecting and storing the steam generated in the boiler group 2, and the pressure-adjusted steam is transferred to the steam use facility 18. Supply.
Further, the steam header 6 is connected to a large-scale boiler system (not shown) such as a water pipe boiler separately from the boiler group 2, and the large-scale boiler system normally uses most of the steam output of the steam header 6. The boiler group 2 will cover the shortfall and make up for the shortfall.

The vapor pressure sensor 7 as the header pressure measuring means is electrically connected to the number control device 3 via the signal line 13. The vapor pressure sensor 7 measures the vapor pressure value inside the vapor header 6 (hereinafter referred to as “header pressure value”), and controls the number of measured vapor pressure signals (vapor pressure signals) via the signal line 13. It is transmitted to the device 3.

The number control device 3 is electrically connected to a plurality of boilers 20 via a signal line 16. The number control device 3 controls the combustion state of each boiler 20 so as to generate steam having a constant output steam amount.

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

[Continuous control boiler 20]
The continuous control boiler 20 is a boiler whose 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. Is. The boiler 20 adjusts the amount of combustion by controlling, for example, the opening degree (combustion ratio) of the valve that supplies fuel to the burner and the valve that supplies combustion air.

Further, to continuously control the combustion amount, when the calculation and the signal in the local control unit 22 are handled in a digital manner in a stepwise manner (for example, the output (combustion amount) of the boiler 20 is controlled in 1% increments). Even in the case where the output can be controlled virtually continuously.

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

(Eco driving zone)
The boiler 20 is set with a range of combustion rates having high boiler efficiency (referred to as "eco-driving zone") and a combustion rate having the highest boiler efficiency (referred to as "eco-driving point"). By continuing to burn the boiler 20 in this eco-driving zone or eco-driving point, the boiler 20 can be burned efficiently.
In the boiler system 1 of the present embodiment, the combustion boiler is burned in the eco-operation zone or the eco-operation point in the output steam amount constant control mode in which the total value of the output steam amounts of the boiler group 2 is controlled to be a constant value. It is preferable to control so as to keep the operation.

(Priority)
In addition, priorities are set for each of the boilers 20. For example, prioritize the combustion of high-priority boilers. When selecting the boiler 20 to start combustion, combustion is started in order from the boiler 20 having the highest priority.
Since the operating time of the boiler 20 having a high priority becomes long and the operating time of the boiler 20 having a low priority becomes short, the operating states of a plurality of boilers 20 are biased. Therefore, in the boiler system 1, the priority order is changed periodically (for example, every 24 hours) to make the operating states of the plurality of boilers 20 uniform.

Next, the configuration of the number control device 3 will be described in detail. As shown in FIG. 1, the number control device 3 includes a control unit 4 and a storage unit 5.

The control unit 4 controls the combustion state and the number of operating units of the boiler 20 by transmitting various instructions to the boiler 20 via the signal line 16 and receiving various data from each boiler 20. When each boiler 20 receives a signal of a combustion state change instruction from the number control device 3, the combustion amount of the corresponding boiler 20 is controlled according to the instruction. The detailed configuration of the control unit 4 will be described later.

The storage unit 5 contains information on the instructions transmitted to each boiler 20, the combustion state received from each boiler 20, the boiler pressure value of the boiler 20, information on the temperature of the supply water supplied to the boiler main body 21, and the like, each boiler 20. Information on setting the unit steam amount U of, information on setting the priority of multiple boilers 20, information on setting on changing the priority (rotation), eco-driving zone of each boiler 20 (range of combustion rate with high boiler efficiency) ), And the upper and lower limits of the header pressure value set by the header pressure range setting unit 46 described later are stored.

Next, the configuration of the control unit 4 will be described in more detail.
The control unit 4 according to the present embodiment controls the output steam amount constant control mode and the header pressure to control the total value of the output steam amounts of the boiler group 2 to be a constant value according to the needs of the user within a predetermined range. It is equipped with a backup control mode that corrects the amount of combustion of each boiler when the above is removed.
In order to realize such a constant output steam amount control mode, as shown in FIG. 2, the control unit 4 includes an output steam amount setting unit 40, a combustion number calculation unit 41, a control target boiler setting unit 42, and a second. 1 A control unit 43, a combustion rate calculation unit 44, and a priority setting unit 45 are included.
Further, in order to realize the backup control mode, the control unit 4 includes a header pressure range setting unit 46, a required steam amount calculation unit 47, a second control unit 48, and a control switching unit 49.

The output steam amount setting unit 40 presets a constant output steam amount, which is the amount of steam output by the boiler group 2.

When the combustion number calculation unit 41 evenly allocates the combustion rate to each boiler 20 included in the boiler group 2 in order to output a constant output steam amount, the combustion rate of each boiler 20 is within the range of the eco-operation zone. Calculate the number of combustion so that it fits within.
Further, the combustion number calculation unit 41 sets in advance a precondition for the number of combustions that specifies whether to suppress or excessive the number of combustions, and when there are a plurality of options or options when calculating the number of combustions. If does not exist, the number of burns is calculated based on the precondition for the number of burns.
As a result, if you want to minimize the number of combustion units, you can specify to suppress the number of combustion units against the preconditions for the number of combustion units, and conversely, if you want to suppress the combustion rate of each boiler, you can use the preconditions for the number of combustion units. By specifying to increase the number of combustion units, it is possible to meet the needs of users.

The control target boiler setting unit 42 sets the boiler 20 for the number of combustion units calculated by the combustion number calculation unit 41 as the control target boiler. Specifically, the control target boiler setting unit 42 sets the control target boilers in order from the boiler with the highest priority.

The first control unit 43 controls the combustion state of the control target boiler 20 set by the control target boiler setting unit 42 so as to generate steam of a constant output steam amount preset by the output steam amount setting unit 40. do. In addition, in order to secure the steam output corresponding to the output steam amount, the first control unit 43 controls the combustion state of the boiler 20 to be controlled so as to output at the actual evaporation amount level.
More specifically, the first control unit 43 burns the control target boiler 20 based on the combustion rate calculated by the combustion rate calculation unit 44 described later based on the boiler pressure and the water supply temperature for each control target boiler 20. Control the state.

The combustion rate calculation unit 44 actually outputs the output from the controlled target boiler 20 based on the temperature of the supply water supplied to the boiler main body 21 of the controlled target boiler 20 and the internal boiler pressure value of the controlled target boiler 20. The combustion rate of the control target boiler 20 is calculated so that the steam amount (also referred to as “actual evaporation amount”) matches the output steam amount set in the control target boiler 20.
Next, the calculation (correction) of the combustion rate based on the boiler pressure and the water supply temperature of the boiler 20 to be controlled will be described.

First, the equivalent evaporation amount and the actual evaporation amount will be described. The equivalent evaporation amount is also referred to as a reference evaporation amount or a conversion evaporation amount, and represents the ability to turn water at 100 ° C. into steam at 100 ° C. under atmospheric pressure, and is used for marking the capacity of a conversion boiler. For example, if the equivalent evaporation amount is 1000 kg / h, it means that it has the ability to turn 1000 kg of water at 100 ° C. into steam at 100 ° C. per hour. On the other hand, when actually evaporating water, the temperature is changed (temperature rise) from the temperature of the water to be supplied (water supply temperature) to the saturation temperature of the pressure to be used, and then the latent heat is changed (evaporation). The actual amount of evaporation is less than the equivalent amount of evaporation as the water supply temperature is lower and the steam pressure is higher.

It is known to those skilled in the art that the equivalent evaporation amount and the actual evaporation amount satisfy Equation 1.
Actual evaporation = (equivalent evaporation x 539) / (total heat of steam-sensible heat of water supply) (Equation 1)
Here, "539" is the amount of heat (kcal / kg) that turns water at 100 ° C. into steam at 100 ° C., and "total heat of steam" is saturated steam (dryness 100%) determined by steam pressure. ) Means the amount of heat (kcal / kg) possessed by), and "the actual heat of the water supply" means the amount of heat (kcal / kg) having the same value as the water supply temperature (° C.). Further, the equivalent evaporation amount is equal to the value obtained by integrating the combustion rate with the boiler capacity.
In this embodiment, the "total heat of steam" is controlled by a "steam table" (tentative name).
For example, when a boiler having a boiler capacity of 7000 kg / h is burned at a combustion rate of 32%, the equivalent evaporation amount is 2240 (= 7000 × 0.32) kg / h.
When the steam pressure is 0.7 MPa, the water supply temperature is 60 ° C., and the equivalent evaporation amount is 2240 kg / h, the "total heat of steam" is 660 kcal / kg and the "sensible heat of water supply" is 60 kcal / kg. The actual evaporation amount has the following value according to Equation 1.
Actual evaporation amount = (2240 × 539) / (660-60) = 2012 kg / h
As described above, the combustion rate calculation unit 44 calculates the actual evaporation amount (kg / h) based on the equivalent evaporation amount (or combustion rate), the boiler pressure value, and the water supply temperature.

FIG. 3A shows an example in which the combustion rate of the controlled boiler 20 is changed so that the total amount of actual evaporation maintains the set output steam amount when the boiler pressure value changes. FIG. 3B shows an example in which the combustion rate of the controlled boiler 20 is changed so that the total amount of actual evaporation maintains the set output steam amount when the water supply temperature changes. The processing contents of the combustion rate calculation unit 44 will be described with reference to FIGS. 3A and 3B.
In FIGS. 3A and 3B, the boiler capacity of each boiler 20 is 7,000 kg / h, the output steam amount is 6000 kg / h, and the number of controlled boilers is three. The three units will be Units 1, 2, and 3.

Referring to FIG. 3A, the boiler pressure value of each boiler at time _{t 0} is 0.70 MPa, the boiler pressure value of each boiler at time _{t 1} changes to 0.90MPa, further boiler pressure value of each boiler at time _{t 2} Shows how it changes to 1.20 MPa.
Referring to Figure 3A, at time _{t 0} and time _{t 1} while the Unit 1 and Unit 2 substantial evaporation of 2240kg / h (32% burn rate), Unit 3 substantial evaporation of 2170kg / h (burn rate 31 %), It can be seen that the total amount of actual evaporation maintains a value close to 6000 kg / h. In contrast, in the time t _2, the by raising the Unit 3 of the combustion of 1%, the total of the fact evaporation, it can be seen that it maintains a value close to 6000 kg / h.

3B, the feed water temperature of the boiler in the feed water temperature of the boiler 60 ° C. At time t _0, the time t ₁ shows exemplary changes 50 ° C..
Referring to Figure 3B, when a to 3 Unit substantial evaporation Unit 1 at time _{t 0} and 2240kg / h (32% firing rate), the sum of the actual amount of evaporation 1996kg / h, and the actual amount of evaporation of the boiler 20 Is 5987 kg / h, and it can be seen that the value close to 6000 kg / h is maintained. In contrast, at time _{t 1,} when the first car to 3 Unit substantial evaporation 2240kg / h (combustion rate 32%) and the actual total amount of evaporation, 5890kg / h, and the set output steam It can be seen that 110 kg / h is insufficient for the amount of 6000 kg / h. Therefore, it can be seen that by increasing the combustion rates of Units 1 and 2 by 1% to 33%, the total amount of actual evaporation is 6012 kg / h, and a value close to 6000 kg / h can be maintained.
As described above, the combustion rate calculation unit 44 corrects the combustion rate (or output steam amount) of the control target boiler 20 based on the boiler pressure and water supply temperature of the control target boiler 20 to obtain the control target boiler 20. It is possible to output a fixed output steam amount set by the output steam amount setting unit 40 without being affected by the water supply temperature and the boiler pressure.

The priority setting unit 45 sets and changes the priority of each boiler 20 included in the boiler group 2. The priority setting unit 46 periodically (for example, every 24 hours) changes the priority in the boiler system 1 so that the operating states of the plurality of boilers are not biased, and the operating states of the plurality of boilers are changed. We are trying to make it uniform.
When the priority of the boiler 20 is changed by the priority setting unit 45, the number control unit 4 starts combustion of the boiler 20 having a higher priority among the boilers 20 in the combustion stopped state, and then the boiler 20 Outputs a predetermined amount of steam to stop the combustion of the low priority boiler.
As a result, the boiler 20 can be burned evenly, and the failure rate of the boiler 20 can be reduced.

The header pressure range setting unit 46 sets the upper limit and the lower limit of the header pressure value in advance. The upper limit value and the lower limit value of the header pressure value are set as threshold values for the control switching unit 49 described later to determine that some abnormality has occurred in a large-scale boiler system such as a water pipe boiler which is a main boiler.

The required steam amount calculation unit 47 calculates the required steam amount based on the header pressure value. Specifically, the required steam amount calculation unit 47 so that the header pressure value maintains the preset target pressure value (or the header pressure value falls within the preset target pressure value range). _{For each predetermined cycle, for example, the current required steam amount MV n} calculated by a known position type PID (or position type PI) algorithm or speed type PID (or speed type PI) algorithm is calculated.

The second control unit 48 controls the combustion state of the boiler group 2 so as to generate the steam of the required steam amount calculated by the required steam amount calculation unit 47. That is, when the header pressure value exceeds the preset target pressure value, the second control unit 48 ignores the set output steam amount and gradually reduces the output steam amount of all the controlled target boilers 20. Let me. On the contrary, when the header pressure value falls below the preset target pressure value, the second control unit 48 ignores the set output steam amount and gradually reduces the output steam amount of all the controlled target boilers 20. increase. By doing so, the pressure stability of the entire boiler system can be ensured.

The control switching unit 49 sets the lower limit of the header pressure value set in advance by the header pressure range setting unit 46 or when the header pressure value exceeds the upper limit of the header pressure value preset by the header pressure range setting unit 46. When the pressure falls below the limit, the control of the combustion state of the boiler group 2 by the first control unit 43 is stopped, and the control of the combustion state of the boiler group 2 by the second control unit 48 is executed.
As a result, when the header pressure is out of the predetermined range, the pressure stability of the entire boiler system can be immediately ensured by switching the output steam amount to the pressure control based on the header pressure.

Next, a series of flow of control by the control unit 4 in the present embodiment will be described with reference to FIGS. 4A to 4C. 4A to 4C are flowcharts showing the processing contents of the control unit 4.

<Setting of output steam amount>
The setting process of the controlled target boiler will be described with reference to FIG. 4A.
It is assumed that the priority of each boiler 20 included in the boiler group 2 is preset by the priority setting unit 45. Further, it is assumed that the upper limit and the lower limit of the header pressure value are set in advance by the header pressure range setting unit 46.
In step ST1, the control unit 4 (output steam amount setting unit 40) presets a constant output steam amount, which is the amount of steam output by the boiler group 2.

In step ST2, the control unit 4 (combustion number calculation unit 41) calculates the number of combustions of the boiler 20 satisfying the condition that the combustion rate of each boiler 20 falls within the range of the eco-driving zone.

In step ST3, the control unit 4 (combustion number calculation unit 41) determines whether or not there is an option for the number of units that satisfy the condition that the combustion rate of each boiler 20 falls within the range of the eco-driving zone. If present (Yes), the process proceeds to step ST4. If it does not exist (No), the process proceeds to step ST5.

In step ST4, the control unit 4 (combustion number calculation unit 41) determines whether or not there are a plurality of options for the number of units. If there are a plurality of options for the number of units (Yes), the process proceeds to step ST5. If there are no options for the number of units (No), the process proceeds to step ST6.

In step ST5, the control unit 4 (combustion number calculation unit 43) selects one option based on the preconditions for the number of combustion units specified in advance.

In step ST6, the control unit 4 (control target boiler setting unit 42) sets the boiler 20 for the number of combustion units calculated by the combustion number calculation unit 43 as the control target boiler.

Next, the process of controlling the constant output steam amount will be described with reference to FIG. 4B.
<Constant output steam amount control>

In step ST7, the control unit 4 (combustion rate calculation unit 44) is a value of an output steam amount in which the total of the actual evaporation amount output by the boiler 20 is constant based on the water supply temperature of the boiler 20 and the boiler pressure value of the boiler 20. The combustion rate of the boiler 20 is calculated so as to be the closest value to.

In step ST8, the control unit 4 (first control unit 43) burns the combustion control boiler 20 at the combustion rate calculated by the combustion rate calculation unit 44.

In step 9, the control unit 4 (control switching unit 49) determines whether or not the header pressure value is within the range of the upper limit and the lower limit set by the header pressure range setting unit 46. If it is within the upper and lower limits (Yes), the process proceeds to step ST10. If it is not within the range of the upper limit and the lower limit (No), the process proceeds to step ST11.

In step ST10, the control unit 4 (combustion rate calculation unit 44) determines whether or not there is a change in the temperature of the supply water supplied to the boiler 20 and the boiler pressure value inside the boiler 20. If there is a change (Yes), the process returns to step ST7. If there is no change (No), the process returns to step ST8.

Next, the process of the backup control mode will be described with reference to FIG. 4C.
In step ST11, the control unit 4 (control switching unit 49) stops the combustion control by the first control unit 43, and causes the second control unit 48 to control the combustion state of the boiler group 2.

In step ST12, the control unit 4 (second control unit 48) controls the combustion state of the boiler group 2 so as to generate the steam of the required steam amount calculated by the required steam amount calculation unit 47.

According to the boiler system 1 of the present embodiment described above, the following effects are obtained.

The control unit 4 according to the boiler system 1 of the present embodiment outputs a constant output steam amount and an output steam amount setting unit 40 that presets a constant output steam amount, which is the amount of steam output by the boiler group 2. Therefore, when the combustion rate is evenly distributed to each boiler 20 included in the boiler group 2, the number of combustion units is calculated so that the combustion rate of each boiler 20 falls within the range of the eco-driving zone. And the control target boiler setting unit 42 that sets the boilers for the number of combustion units calculated by the combustion number calculation unit 41 as the control target boiler, and the control target boiler setting unit 42 so as to generate steam with a constant output steam amount. A first control unit 43 that controls the combustion state of the boiler to be controlled set by
As a result, it is possible to realize constant output amount control that is not affected by the header pressure or the boiler pressure. For example, in a boiler system in which a large-scale boiler system such as a water pipe boiler is used as a main boiler group and the boiler system 1 of the present embodiment is used as a sub-boiler group, when pressure is controlled by the main boiler group, the boiler of the present embodiment is used. The system 1 can perform fixed combustion at a constant output without performing pressure control as a sub-boiler group.

Further, the combustion rate calculation unit 44 determines the amount of output steam actually output from the boiler 20 based on the temperature of the supply water supplied to the boiler main body 21 of the boiler 20 and the boiler pressure value inside each boiler 20. The combustion rate of the boiler 20 is calculated so as to match the output steam amount set for each boiler. As a result, the output steam amount is set by the output steam amount setting unit 40 without being affected by the water supply temperature and the boiler pressure. It is possible to output a fixed output steam amount.

Further, the combustion number calculation unit 41 sets in advance a precondition for the number of combustions that specifies whether to suppress or excessive the number of combustions, and when calculating the number of combustions, when there are a plurality of options or options are available. If it does not exist, the number of burns is calculated based on the precondition for the number of burns.
As a result, if you want to minimize the number of combustion units, you can specify to suppress the number of combustion units against the preconditions for the number of combustion units, and conversely, if you want to suppress the combustion rate of each boiler, you can use the preconditions for the number of combustion units. By specifying to increase the number of combustion units, it is possible to meet the needs of users.

Further, the priority setting unit 45 sets and changes the priority of each boiler 20 included in the boiler group 2. When the priority of the boiler 20 is changed by the priority setting unit 45, the number control unit 4 starts combustion of the boiler 20 having a higher priority among the boilers 20 in the combustion stopped state, and then the boiler 20 Outputs a predetermined amount of steam to stop the combustion of the low priority boiler.
As a result, the boiler 20 can be burned evenly, and the failure rate of the boiler 20 can be reduced.

Further, the control unit 4 according to the boiler system 1 of the present embodiment has a second control unit 48 that controls the combustion state of the boiler group 2 so as to generate the required amount of steam calculated based on the header pressure value. , When the header pressure value exceeds the upper limit of the preset header pressure value or falls below the lower limit of the preset header pressure value, the first control unit 43 controls the combustion state of the boiler group 2. A control switching unit 49 is provided, which is stopped and the second control unit 48 controls the combustion state of the boiler group 2.
As a result, for example, when the header pressure falls out of the predetermined range due to some abnormality in a large-scale boiler system such as a water pipe boiler which is the main boiler, the output steam amount is switched to the pressure control based on the header pressure. , The pressure stability of the entire boiler system can be ensured.

Although the preferred embodiment has been described above, the present invention is not limited to the above embodiment, and can be implemented in various forms.

[Modification 1]
In the above embodiment, when the header pressure value deviates from the upper and lower limit ranges preset by the header pressure range setting unit 46, the control switching unit 49 is in the combustion state of the boiler group 2 by the first control unit 43. However, the control of the combustion state of the boiler group 2 by the second control unit 48 is executed by stopping the control of the above, but the present invention is not limited to this. The control switching unit 49 may switch all boilers 20 to manual operation when the header pressure value deviates from the upper and lower limit ranges preset by the header pressure range setting unit 46.

[Modification 2]
For example, in the above embodiment, all the continuous control boilers 20 have the same boiler capacity, but the present invention is not limited to this. That is, it can be applied even when the minimum combustion amount, the unit steam amount, and the combustion capacity as the maximum combustion amount are different for each boiler 20.

[Modification 3]
Further, in the above embodiment, the present invention is applied to a boiler system including a boiler group 2 composed of three continuous control boilers 20, but the present invention is not limited to this. That is, the present invention may be applied to a boiler system including a boiler group consisting of two or four or more boilers. Further, it may be applied to one boiler alone.

[Modification example 4]
Further, in the above embodiment, the required steam amount calculation unit 47 calculates the required steam amount (indicated steam amount) by the PID (proportional + integral + differential) algorithm based on the steam pressure value (physical quantity) of the steam header 6. Was explained. Not limited to this, the present invention can also be applied to control for calculating the required vapor amount (indicated vapor amount) by the PI (proportional + integral) algorithm or the P (proportional) algorithm.

[Modification 5]
In the above embodiment, the control unit 4 may include, in addition to the constant output steam amount control mode, a pressure control mode in which combustion control is performed so that the header pressure value maintains a preset target value.
In this case, the control unit 4 may be configured to change from the constant output steam amount control mode to the pressure control mode, and conversely, from the pressure control mode to the constant output steam amount control mode by an external signal or the like.
As a result, when the boiler system 1 is used as an auxiliary application for a main boiler such as a water pipe boiler and steam supply is required due to a failure of the main boiler or the like, the control mode is output by an external signal or the like. By changing from constant control to pressure control, it is possible to restore the steam system in a short time.

1 Boiler system 2 Boiler group 3 Number control device 4 Control unit 40 Output steam amount setting unit 41 Combustion number calculation unit 42 Controlled boiler setting unit 43 1st control unit 44 Combustion rate calculation unit 45 Priority setting unit 46 Header pressure range setting Unit 47 Required steam amount calculation unit 48 Second control unit 49 Control switching unit 5 Storage unit 6 Steam header 7 Steam pressure sensor (header pressure measuring means)
18 Steam use equipment 20 Boiler 21 Boiler body 22 Local control unit 23 Water supply temperature measurement unit 24 Steam pressure sensor (boiler pressure measurement unit)

Claims (6)

A group of boilers consisting of one or more boilers that can be burned by continuously changing the combustion rate,
A steam header that collects the steam generated in the boiler group,
A unit control unit that controls the combustion state of the boiler group, and
It is a boiler system equipped with
For one or more boilers mentioned above
An eco-driving zone, which is a range of combustion rates at which the boiler efficiency becomes higher than a predetermined value, is set for each boiler.
The number control unit
An output steam quantity setting unit for setting beforehand a constant output amount of steam which is not affected by the header pressure value is an internal vapor pressure of the steam header I sum der full power steam amount outputted by the boiler group,
Combustion of each boiler when the combustion rate is evenly distributed to each boiler included in the boiler group in order to output the constant output steam amount that is not affected by the header pressure value which is the steam pressure inside the steam header. A combustion number calculation unit that calculates the number of combustion so that the rate falls within the range of the eco-driving zone, and
A control target boiler setting unit that sets the boilers for the number of combustion units calculated by the combustion number calculation unit as control target boilers, and
The total value of the total output steam output by the controlled target boiler set by the controlled target boiler setting unit without performing pressure control based on the header pressure value is the steam pressure inside the steam header. The combustion state of the controlled target boiler set by the controlled target boiler setting unit is controlled so as to generate steam of a constant output steam amount preset by the output steam amount setting unit that is not affected by the header pressure value. 1st control unit and
Boiler system with. A boiler pressure measuring means for measuring a boiler pressure value, which is the vapor pressure inside the boiler, and a boiler pressure measuring means.
A water supply temperature measuring means for measuring the water supply temperature, which is the temperature of the water supply supplied to the boiler body of the boiler, and
A combustion rate calculation unit that calculates a combustion rate that outputs a given amount of steam based on the water supply temperature and the boiler pressure value.
With
The first control unit further
The boiler system according to claim 1, wherein the combustion state of the boiler to be controlled is controlled based on the combustion rate calculated by the combustion rate calculation unit. The combustion number calculation unit
Preconditions for the number of burned units that specify whether to suppress or exceed the number of burned units are set in advance.
The boiler system according to claim 1 or 2, wherein when calculating the number of combustion units, the number of combustion units is calculated based on the precondition for the number of combustion units when a plurality of options exist or there are no options. A header pressure measuring means for measuring a header pressure value which is a vapor pressure inside the steam header, and
A header pressure range setting unit that presets the upper and lower limits of the header pressure value, and
A required steam amount calculation unit that calculates the required steam amount based on the header pressure value, and
A second control unit that controls the combustion state of the boiler group so as to generate steam of the required steam amount calculated by the required steam amount calculation unit.
When the header pressure value exceeds the upper limit or falls below the lower limit, the control of the combustion state of the boiler group by the first control unit is stopped, and the control of the combustion state of the boiler group by the second control unit is stopped. The boiler system according to any one of claims 1 to 3, further comprising a control switching unit for executing control of a combustion state. The number control unit further
It is provided with a priority setting unit for setting and changing the priority of each boiler included in the boiler group.
According to any one of claims 1 to 4, when the priority of each boiler is changed by the priority setting unit, combustion of a boiler having a higher priority among the boilers in the combustion stopped state is started. Described boiler system. The number control unit
The boiler system according to claim 5, wherein when the priority of each boiler is changed by the priority setting unit, combustion of a boiler having a lower priority among the boilers in a combustion state is stopped.

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