JP2011247538A - Multi-can installed boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly consume gas fuel supplied from biogas manufacturing facilities and secure an amount of steam quantity that meets the demand of users under a stable operation.SOLUTION: A multi-can installed boiler includes a plurality of first boilers 1a that have no limit in an amount of supply of a fuel needed for steam generation as a boiler and a second boiler 1b whose amount of supply of the gas fuel needed for steam generation varies and is limited by the amount of supply from a fuel supplier. The first boiler 1a is configured to have capability to cover a shortage of the generated steam amount by the second boiler 1b. A first boiler quantity controller 4 is provided that outputs drive directions to the plurality of first boilers 1a based on the steam pressure of a steam aggregation section 8. Further, a second boiler controller 5 is provided that makes the amount of medium generated in the second boiler 1b equivalent to the pressure of the gas fuel based on the pressure of the gas fuel supplied to the second boiler 1b.

Description

  The present invention relates to a multi-can boiler for industrial use and business use, and more specifically, includes a plurality of boilers installed in parallel, and a medium which is a heat medium such as hot water, steam or oil generated from the boiler. The present invention relates to a multi-can installation boiler that gathers at a gathering section and supplies it to a medium demand destination.

  Such a multi-can installation boiler supplies a medium (hot water, steam, or heat medium) having a required temperature from the medium collecting unit to the medium demand destination according to the use of the medium demand destination. Here, for easy understanding, in the following description, the case where the medium is steam is mainly described.

  As an operation control form of each boiler in a multi-can installation boiler, “individual steam pressure number control” as shown in FIG. 2 and “centralized steam pressure number control” as shown in FIG. 3 are known.

“Individual steam pressure unit control” provides each boiler B with a pressure detector PI and a boiler operation controller PS1 that controls the start and stop of the boiler based on the detection result of the pressure detector PI, and controls each boiler. For example, the operation is stopped when the pressure of the steam generated from the boiler exceeds the set pressure, and the operation is restarted when the pressure falls below the set pressure. As specific control, two-position control that repeats boiler operation-stop (ON-OFF control) corresponding to a set pressure is well known. Furthermore, as the set pressure, a high pressure for high combustion (high set pressure) and a low pressure for low combustion (low set pressure) are provided, and the pressure of steam generated from the boiler exceeds the high set pressure. If it is between the high set pressure and the low set pressure, the low combustion state is maintained (LOW), and if the pressure falls below the low set pressure, the operation is changed to the high combustion state. (HI), and this form is called three-position control because the combustion state is controlled between the high combustion state (HI), the low combustion state (LOW), and the stop (OFF).
In this "individual steam pressure unit control", if there is a boiler that you want to use preferentially, set the set pressure for stopping that boiler higher than other boilers so that the boiler will be operated longer than other boilers. Thus, the boiler is used preferentially.

In the “centralized steam pressure unit control”, a pressure detector PI is provided in a steam collecting portion M (an example of a medium collecting portion) that is a collecting portion of steam generated from each boiler B, and the detection result of the pressure detector PI. Based on the above, the number controller PS2 for controlling the start and stop of each boiler is provided, the boiler to be operated by this number controller PS2 is determined, and the operation command is output to the boiler. Generates a vapor amount commensurate with the amount.
When there is a boiler to be preferentially used in this “centralized steam pressure unit control”, the unit controller stores the boiler information to be prioritized and starts the boiler preferentially. In this type of number control, the number of boilers may be controlled according to the steam temperature in addition to the steam pressure at the steam collecting part M, which is a steam collecting part.
Patent Document 1 discloses a multi-can installation boiler that selectively executes the above-described number control and centralized control.

JP 2009-281708 A

  Recently, it has been attempted to reduce the consumption of fossil fuels as much as possible for the purpose of preventing global warming, for example, to generate biogas by using bio-derived industrial residues and to use the stored energy as fuel. . As this type of biological gas, gas obtained by decomposing organic components into methane in an anaerobic fermenter is typically known, and biogas obtained in this way is desulfurized, pressurized, After storage, it is supplied as gas fuel to boiler equipment and used for steam generation. Since this type of biogas has various production states of industrial residues used for generation, for example, the amount of biogas generated varies greatly from day to day to about 20 to 100% of the rated generation amount.

  In boilers that use gas fuel that may vary in this type of generation, the amount of gas fuel required to generate steam varies, and the amount of supply is limited by the amount supplied from the fuel supply side. . Moreover, when the supply amount of gas fuel falls below a prescribed amount, the boiler is stopped.

  On the other hand, if the supply from the gas fuel supply side is continued in such a stopped state of the boiler, the pressure of the gas fuel on the supply side will increase too much, and the gas fuel will be diffused to the outside air. Dissipation of the outside air is not preferable because it has a large influence on the environment.

Problems of “Individual Steam Pressure Unit Control” When this control mode is adopted, in general, in order to use biogas as much as possible, the operating steam set pressure of the boiler is increased (in order to increase the steam pressure). By continuing the operation until it becomes, the number control method of operating the boiler with priority over other standard boilers that can receive sufficient fuel supply is adopted. In general, biogas is boosted and sent to the boiler. When the amount of biogas generated is less than the amount consumed by the boiler, and the biogas supply pressure falls below a certain pressure, the boiler stops. That is, when a standard boiler capable of receiving only a necessary amount of biogas and fuel is operated by the individual vapor pressure unit control method, boilers using biogas frequently start and stop, At the same time as stopping, the biogas supply pressure rises to a certain level, and an operation signal is input to the boiler. At this time, the timing of restarting the boiler using the biogas is delayed, and the supply pressure When reaches the limit value, biogas is released from the safety valve into the atmosphere.

Problems of “Centralized Steam Pressure Unit Control” When this control mode is adopted, the number of units to be operated is controlled based on the information of the steam collecting part M where the steam from all the boilers is concentrated. It is the basis of this control form that there is no big difference in capability. Under these circumstances, if the boiler that receives the supply of biogas is used preferentially, the boiler that operates with the highest priority will be the boiler. The possibility of fluctuation in the amount of gas fuel supplied to the priority boiler is the highest, and the highest priority boiler will be subject to the regulation of the amount of gas fuel supplied, and the operation of other normal boilers will have the highest priority It is greatly affected by the operating condition of the boiler. As a result, a stable operation state of the equipment itself cannot be achieved.

  An object of the present invention is to ensure reliable consumption of gas fuel supplied in a multi-can boiler having a boiler in which the amount of gas fuel supplied varies and the amount of generated medium is regulated by the amount of gas fuel supplied. The aim is to obtain a multi-can installation boiler that can supply a medium that meets the demand of the customer in a stable operating state.

In order to achieve the above-mentioned object, the characteristic configuration of the multi-can installation boiler that includes a plurality of boilers installed in parallel, collects the medium generated from the boiler at the medium collecting unit, and supplies the medium to the customer.
As the boiler, there is a first boiler with no restriction on the supply amount of fuel necessary for generating the medium, and the supply amount of gas fuel required for generating the medium varies, and the supply amount is the supply amount from the fuel supply side. With a second boiler limited by
The first boiler is configured to have an ability to cover the shortage of the generated medium amount of the second boiler with the first boiler,
With a first boiler control device that outputs an operation command to the first boiler based on the medium temperature or the medium pressure of the medium assembly unit,
A second boiler control device is provided that sets the amount of medium generated in the second boiler to an amount corresponding to the amount or pressure of the gas fuel based on the amount or pressure of gas fuel supplied to the second boiler. It is in.

In this multi-can boiler, the supply amount of the fuel required for generating the medium is not limited, the supply amount of the gas fuel required for generating the medium fluctuates, and the supply amount is the fuel. A second boiler is provided which is limited by the supply amount from the supply side.
And a 1st boiler control apparatus works with respect to a 1st boiler, and a 2nd boiler control apparatus works with respect to a 2nd boiler. Here, the second boiler control device determines the amount of medium generated in the second boiler based on the amount or pressure of the gas fuel supplied to the second boiler and the amount corresponding to the amount or pressure of the gas fuel. Thus, the amount of gas fuel consumed in the second boiler is set to an amount commensurate with the amount of gas fuel supplied. As a result, the second boiler continues its operation as long as the amount of gas fuel to be supplied is not extremely reduced, and generates a medium corresponding to the amount of gas fuel to be supplied.

On the other hand, the first boiler is controlled by the first boiler control device that outputs an operation command to the first boiler based on the medium temperature or the medium pressure of the medium collecting unit, and only meets the medium requirement of the demand destination. In order to supply the medium to the customer, the amount of medium generated from the second boiler is insufficient.
As a result, in a multi-can boiler equipped with a boiler (second boiler) in which the amount of gas fuel varies and the amount of steam generated is regulated by the amount of gas fuel supplied, reliable consumption of the gas fuel supplied In addition, it is possible to supply a medium that meets the demand of the customer in a stable operating state.

In the multi-can installation boiler having the above-described characteristic configuration,
The operation control mode for the first boiler by the first boiler control device is a two-position control mode in which the first boiler is ON-OFF controlled based on the medium temperature or the medium pressure of the medium collecting unit, or HI-LOW- It is a three-position control mode that performs OFF control,
The operation control mode for the second boiler by the second boiler control device is based on the amount or pressure of the gas fuel supplied to the second boiler, and the amount of generated medium as the amount or pressure of the gas fuel increases. It is preferable to use a proportional control mode that increases.

By adopting this configuration, for the first boiler, for example, “concentrated number control” as in the past is adopted, and the operation stop of the first boiler is controlled in two or three positions. The control can compensate for the shortage that is insufficient with only the operation of the second boiler with respect to the demand of the customer.
On the other hand, in the second boiler, the medium corresponding to the amount of gas fuel to be supplied can be used and consumed for generating the medium, and the medium can be generated while consuming the gas fuel stably without excess or deficiency.

Furthermore, it is preferable that the gas fuel supplied to the second boiler is a biogas fuel mainly composed of biologically derived methane.
From the viewpoint of both energy problems and environmental problems, it is preferable to produce and effectively use biogas fuel mainly composed of methane. However, the biofuel produced by using the multi-can installed boiler described so far The above object can be achieved by consuming the gas fuel as the gas fuel.
In addition, the production amount of this type of biogas tends to fluctuate, and the production amount may decrease to less than half of the normal production amount. However, the multi-can boiler of the present invention satisfies the supply of the customer. In this state, the biogas can be used effectively.

Regarding the multi-can installation boiler that has been described so far, a plurality of the first boilers are provided, and the first boiler control device is related to the plurality of first boilers based on the medium temperature or the medium pressure of the medium assembly unit, If it is set as the structure which controls the number of the 1st boilers which operate | move, about the 1st boiler, the conventional "centralized number control" will be adopted, number control will be performed appropriately, and the 2nd boiler with respect to the demand of a customer It is possible to make up for the shortage that is lacking by driving alone.
On the other hand, in the second boiler, a medium corresponding to the amount of gas fuel supplied can be used and consumed for generating the medium, and the medium can be generated while consuming gas fuel stably without excess or deficiency.

Moreover, regarding the multi-can installation boiler described so far, the first boiler control device controls the amount of steam generated from the first boiler based on the medium temperature or the medium pressure of the medium collecting unit. You can also. In this case, the first boiler can make up for a shortage that is insufficient with only the operation of the second boiler with respect to the demand of the customer.
As for the second boiler, the medium corresponding to the amount of gas fuel to be supplied can be used and consumed for generating the medium, and the medium can be generated while consuming gas fuel stably without excess or deficiency.

Therefore, the supply pressure of the biogas supplied to the second boiler is stabilized, and the frequency of stopping the second boiler due to the diffusion of the outside air due to the pressure abnormality or the pressure drop can be reduced. Furthermore, usually, a biogas generation plant is often provided with a small cushion tank (holder) in order to absorb the influence of the flow rate fluctuation on the second boiler side. By adopting this control system, The tank capacity can be further reduced or omitted, and the overall system cost can be reduced.
In addition, the frequency of starting and stopping the second boiler is reduced, the operating efficiency (ratio of the amount of steam generated with respect to the biogas consumption) is also increased, and energy is saved.

The figure which shows the structure of the multi-can installation boiler which concerns on this application Diagram showing the configuration of a multi-can installation boiler for "Individual Steam Pressure Unit Control" Diagram showing the configuration of a multi-can installation boiler for “Centralized Vapor Pressure Unit Control”

A multi-can installation boiler 100 according to the present invention will be described with reference to FIG.
The multi-can installation boiler 100 includes a plurality of boilers 1 installed in parallel, and collects steam generated from the boiler 1 at a steam collecting unit 2 (an example of a medium collecting unit), and the steam shown on the right side of FIG. This is a facility that supplies the customer 3 (an example of a medium customer).

  In the multi-can boiler 100, the supply amount of gas fuel such as natural gas, LPG or heavy oil, which has substantially no limit on the supply amount of fuel (first fuel), and biogas, etc. Steam is generated using gas fuel (second fuel) whose supply amount is limited by the supply amount from the fuel supply side as fuel.

Hereinafter, an example of providing a plurality of first boilers 1a and controlling the number of first boilers 1a will be described first.
In the multi-can installation boiler 100, as the boiler 1, a plurality of (four in the illustrated example) first boilers 1a that have no limitation on the supply amount of fuel (for example, natural gas, heavy oil) necessary for generating steam, and steam The amount of gas fuel required for generation fluctuates, and the total amount of steam generated in the second boiler 1b, which is limited by the amount of supply from the fuel supply side, is less than the total amount of steam generated in the first boiler 1a. Alternatively, when the amount of generated steam per unit is the same, a small number (one in the illustrated example) is provided.

  And in this multi-can installation boiler 100, the vapor | steam generation | occurrence | production of the above-mentioned 2nd boiler 1b in the state where the vapor | steam demand in the vapor | steam demand destination 3 increased and the necessity for increasing the amount of steam generation in the multi-can installation boiler 100 generate | occur | produced. Even when the amount is limited due to the limitation of the amount of gas fuel supplied to the second boiler 1b, the first boiler 1a has the ability to cover the shortage of the generated steam amount of the second boiler 1b with the first boiler 1a. It is configured. Specifically, the total steam generation capacity of the second boiler 1b is set to 30% or less of the total steam generation capacity of the entire facility, and the majority of all the first boiler 1a is the largest of the 30% capacity. The equipment is configured to cover for the ability to drive.

  As shown in FIG. 1, based on the steam pressure of the steam gathering part 2 demonstrated previously, the 1st boiler number control apparatus 4 (output of a 1st boiler control apparatus) which outputs a driving | operation command with respect to several 1st boiler 1a. And a second boiler control device 5 that sets the amount of steam generated in the second boiler 1b to an amount corresponding to the pressure of the gas fuel based on the pressure of the gas fuel supplied to the second boiler 1b. It has been.

  More specifically, the operation control mode for the first boiler 1a by the first boiler number control device 4 is a two-position control in which the first boiler 1a is ON-OFF controlled based on the steam pressure of the steam collecting section 2. Has been. On the other hand, the operation control mode for the second boiler 1b by the second boiler control device 5 is a proportional control mode for increasing the amount of steam generated as the pressure rises based on the pressure of the gas fuel supplied to the second boiler 1b. It is said that. And it is comprised so that the whole quantity of the biogas fuel supplied in the 2nd boiler 1b may be consumed substantially.

  The above is the schematic configuration of the multi-can installation boiler 100 according to the present invention. Hereinafter, the generation of gas fuel in the second boiler 1b, the configuration and operation of the multi-can installation boiler 100 will be described.

[Generation of gas fuel]
As shown in the upper part of FIG. 1, the gas fuel used in the second boiler 1 b is supplied to the second boiler 1 b through the raw material receiving tank 10, the anaerobic fermentation tank 11, the desulfurization tank 12, the compressor 13, and the small gas tank 14. Is done.
The raw material receiving tank 10 receives food residues, livestock manure, human waste, rice straw, thinned wood, and the like as raw materials.
The anaerobic fermenter 11 is fermented with known anaerobic bacteria in an anaerobic atmosphere. By the anaerobic fermentation treatment in the anaerobic fermenter 11, the raw material becomes a gas containing approximately 60% of methane and approximately 40% of carbon dioxide.
The gas fuel produced in this manner is desulfurized in the desulfurization tank 12 and the sulfur component contained in the gas fuel is removed, and compressed by the compressor 13 to about 1 kPa to 100 kPa. The gas fuel in a compressed state after compression is stored in the small gas tank 14 and is sequentially supplied according to the operation of the second boiler 1b.

[Configuration and operation of multi-can boiler]
As described above, the multi-can boiler 100 has four first boilers 1a and one second boiler 1b installed in parallel, and steam generated in each boiler 1a, 1b. Are provided with a steam header 6 that is sent to the steam demand 3. Each boiler 1a, 1b and the steam header 6 are connected by a steam pipe 7, and steam generated in each boiler 1a, 1b is sent to the steam header 6 through the steam pipe 7. Each boiler 1a, 1b is provided with a boiler operation control unit 8, and combustion control (including operation / stop of the boiler) in each boiler is performed by the boiler operation control unit 8.
Here, regarding the 1st boiler 1a, the boiler operation control part 8 receives the operation command from the said 1st boiler number control apparatus 4, and performs combustion control. With respect to the second boiler 1b, the boiler operation control unit 8 receives an operation command from the second boiler control device 5 and executes combustion control.

Number control of the first boiler The steam collecting section 2 at the demand end connecting end of the steam header 6 (the steam demand leading end side where steam from all the boilers 1 collects) has a steam collecting section for detecting the steam pressure in the steam collecting section 2. The pressure detector 2a is provided, and the steam collecting portion pressure detector 2a employs a configuration that sends the detection result to the first boiler number control device 4. The first boiler number control device 4 is based on a comparison between the steam pressure value of the steam collecting portion 2 detected by the steam collecting portion pressure detector 2a and the set pressure value set in the first boiler number control device 4. An operation command to each first boiler 1a is generated and transmitted. In the first boiler number control device 4, the number of combustion of the first boiler 1a is decreased as the steam pressure value detected by the steam collecting portion pressure detector 2a is increased, and the number of combustion of the first boiler 1a is decreased as the steam pressure value is decreased. The number of units is determined so as to increase the number. The first boiler number control device 4 sets an operation priority for each boiler 1a, and outputs a combustion request signal to the determined number of boilers in order from the highest operation priority by communication. To do. The operation priority of the boilers here is, for example, in the order of the first boiler 1, the first boiler 2, the first boiler 3, and the first boiler 4 in the order of first, second, third, and fourth. deep. In addition, in order to ensure safety in each boiler 1a, the steam pressure is also detected, and the first boiler 1a can be stopped even when the steam pressure becomes abnormally high.

Second Boiler Control As shown in FIG. 1, the steam generated by the second boiler 1b is also sent to the steam header 6 through the steam pipe 7. The operation of the second boiler 1b is the second characteristic of the present invention. The operation of the boiler control device 5 is controlled. As shown in the figure, the gas fuel supply section 9 for supplying gas fuel to the second boiler 1b is provided with a gas fuel supply section pressure detector 9a for detecting the gas fuel pressure in the gas fuel supply section 9. Yes. The gas fuel supply unit pressure detector 9a adopts a configuration in which the detection result is sent to the second boiler control device 5, and the second boiler control device 5 detects the gas fuel pressure detected by the gas fuel supply unit pressure detector 9a. Based on the value, an operation command to the second boiler 1b is generated and transmitted. In the second boiler control device 5, the combustion amount of the second boiler 1b is increased as the gas fuel pressure value detected by the gas fuel supply pressure detector 9a is increased, and the second boiler 1b is decreased as the gas fuel pressure value is decreased. Reduce the amount of combustion. That is, with respect to the pressure of the gas fuel supplied to the second boiler 1b, the combustion amount of the boiler (in other words, the amount of steam generated) is in a proportional control form in which the amount of steam generated increases as the pressure detection value increases. The proportionality coefficient is a coefficient that determines the combustion amount so as to consume the entire amount of biogas fuel supplied in the second boiler 1b. In order to ensure safety, the steam pressure is also detected, and the second boiler 1b can be stopped even when the steam pressure becomes abnormally high.

  Therefore, in the multi-can installation boiler 100 according to the present invention, with respect to the supply of steam to the steam customer 3, the second boiler 1b generates steam as much as it consumes the gas fuel supplied to the second boiler 1b, The steam generated in the plurality of first boilers 1a is added to the generated steam. As a result, the number of first boilers 1a is controlled so as to follow the amount obtained by subtracting the amount of steam generated in the second boiler 1b from the total steam load required at the steam demand destination 3.

  As a result, the first steam generation system 101 in which the multi-can installation boiler 100 of the present invention is installed and operated with normal fuel, the generation amount of biogas and the like fluctuate, and the generation amount is substantially difficult to control. In the steam generation system (which is also a biogas plant referred to in the present application) including the second steam generation system 102 subject to the regulation of the generation amount, the second boiler 1b is supplied to the second boiler 1b. The first boiler 1a is operated to make up for the shortage that meets the demand of the steam customer 3 while consuming the generated gas fuel without excess and deficiency and generating steam. It is possible to make the operation of the second boiler 1b relatively stable, and to further reduce the chance of diffusion to the outside air as much as possible. Further, the compressor 13 and the tank 14 for gas fuel provided in the second steam generation system 102 can be made relatively small.

  By adopting the equipment configuration of the present invention with respect to the conventional equipment configuration, it is possible to obtain about 10% energy saving (equivalent to an increase in the efficiency of the biogas boiler and a decrease in the amount of biogas diffused).

[Another embodiment]
(1)
In the above embodiment, an example in which the medium generated by the boiler is steam has been described, but this type of medium may be a heat medium such as warm water or oil.
(2)
In the above embodiment, the gas fuel supplied to the second boiler is an example of biogas, but the supply amount varies, and as the gas fuel whose supply amount is regulated in the operation of the second boiler, In addition to biogas, by-product gas, coke gas, and the like generated as by-products in a predetermined process can be used as gas fuel for the second boiler in the present application.
(3)
In the above embodiment, the combustion mode of the first boiler is the two-position control. However, a so-called three-position control may be used in which the combustion state is switched between high output, low output, and stop according to the medium pressure.
(4)
In the above embodiment, an example in which the first boiler number control device determines the number of operating first boilers based on the steam pressure of the steam collecting portion that is the medium collecting portion has been described, but it has also been described above. Thus, the number of operating first boilers may be determined based on the temperature of the steam collecting portion.
On the other hand, regarding the second boiler control device, as described in the previous embodiment, in addition to controlling the combustion amount of the boiler according to the pressure of the gas fuel supplied to the second boiler, the amount of gas fuel, that is, You may control the combustion amount of a 2nd boiler based on the flow volume per unit time which flows through the flow measurement site | part in the gas fuel supplied to a 2nd boiler.
(5)
In the above embodiment, a plurality of first boilers are provided as the first boiler, and the number of the first boilers is controlled by the first boiler number control device which is the first boiler control device. In addition, the first boiler control device outputs an operation command to the first boiler based on the medium temperature or the medium pressure of the medium collecting unit. With respect to at least one first boiler, the operation state of the first boiler may be controlled so that the amount of steam (an example of a medium) supplied from the medium assembly unit to the demand side satisfies a predetermined demand amount condition. .
For example, when the first boiler is controlled at three positions and the supply amount to the demand side is insufficient, the supply amount from the first boiler is increased, and the supply amount to the demand side is excessive, What is necessary is just to reduce the supply amount from 1 boiler, or to stop a 1st boiler.

  In a multi-can installation boiler equipped with a boiler that uses gas fuel such as biogas as its fuel, the supply amount of which varies, and the amount of steam generated is regulated by the supply amount of the gas fuel. As a result, it was possible to obtain a multi-can installation boiler that can supply a medium that meets the demand of the customer in a stable operating state.

1: Boiler 1a: 1st boiler 1b: 2nd boiler 2: Steam gathering part 3: Steam demand 4: 1st boiler number control device (1st boiler control device)
5: Second boiler control device 8: Boiler operation control device 9: Gas fuel supply unit

Claims (5)

A multi-can installation boiler that includes boilers installed in parallel, collects the medium generated from the boiler at the medium assembly unit, and supplies the medium to customers.
As the boiler, there is a first boiler with no restriction on the supply amount of fuel necessary for generating the medium, and the supply amount of gas fuel required for generating the medium varies, and the supply amount is the supply amount from the fuel supply side. With a second boiler limited by
The first boiler is configured to have an ability to cover the shortage of the generated medium amount of the second boiler with the first boiler,
With a first boiler control device that outputs an operation command to the first boiler based on the medium temperature or the medium pressure of the medium assembly unit,
A second boiler control device comprising a second boiler control device for setting the amount of medium generated in the second boiler to an amount corresponding to the amount or pressure of the gas fuel based on the amount or pressure of gas fuel supplied to the second boiler. Can installation boiler. The operation control mode for the first boiler by the first boiler control device is a two-position control mode in which the first boiler is ON-OFF controlled based on the medium temperature or the medium pressure of the medium collecting unit, or HI-LOW- It is a three-position control mode that performs OFF control,
The operation control mode for the second boiler by the second boiler control device is based on the amount or pressure of the gas fuel supplied to the second boiler, and the amount of generated medium as the amount or pressure of the gas fuel increases. The multi-can installation boiler according to claim 1, which is a proportional control mode for increasing   The multi-can installation boiler according to claim 1 or 2, wherein the gas fuel supplied to the second boiler is a biogas fuel mainly composed of biologically derived methane.   A plurality of the first boilers, wherein the first boiler control device controls the number of first boilers to be operated on the plurality of first boilers based on the medium temperature or the medium pressure of the medium collecting unit. The multi-can installation boiler as described in any one of claim | item 1 -3.   The multi-can installation boiler according to any one of claims 1 to 3, wherein the first boiler control device controls the amount of steam generated from the first boiler based on a medium temperature or a medium pressure of the medium collecting unit. .

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