Number-of-units

Abstract

To provide a number-of-units control device capable of efficiently operating an electric boiler.SOLUTION: A number-of-units control device that controls a plurality of boilers including a plurality of fuel boilers and a plurality of electric boilers, acquires steam pressures of steam generated in the plurality of boilers, controls the plurality of boilers on the basis of the steam pressures, causes the plurality of electric boilers to generate a predetermined steam amount after the steam pressures reach a predetermined value, and causes the plurality of fuel boilers to generate a steam amount exceeding the predetermined steam amount.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a boiler number control device for controlling a plurality of boilers. [Background technology]

[0002] Electric boilers that use electricity to generate steam have been known for some time (for example, Patent Document 1). Furthermore, efforts are underway to utilize electricity generated using renewable energy sources in order to achieve carbon neutrality. Accordingly, demand for electric boilers is increasing, and there is a trend toward installing electric boilers and fuel boilers side by side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-169356 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional unit count control devices increase or decrease the number of electric boilers and fuel boilers in operation in response to changes in the steam load, for example, but do not take into consideration keeping electric boilers in operation as long as possible. As a result, there is a risk that electric boilers cannot be operated in a way that makes effective use of electricity.

[0005] The present invention has been devised in view of the above circumstances, and its object is to provide a unit number control device that can operate electric boilers so as to make efficient use of electric power. [Means for solving the problem]

[0006] In order to achieve the above object, a number of units control device according to one aspect of the present invention is a number of units control device that controls a plurality of boilers including a plurality of fuel boilers and a plurality of electric boilers, the number of units control device comprising: a steam pressure acquisition unit that acquires steam pressures of steam generated in the plurality of boilers; a control unit that controls the plurality of boilers based on the steam pressure, The control unit controls the plurality of electric boilers to generate a predetermined amount of steam after the steam pressure reaches a predetermined value, and controls the plurality of fuel boilers to generate an amount of steam exceeding the predetermined amount of steam.

[0007] According to the above configuration, after the steam pressure reaches a predetermined value, the predetermined amount of steam is generated by the electric boilers, and the amount of steam exceeding the predetermined amount (the fluctuating amount of steam) is generated by the fuel boilers. Therefore, compared to when an amount of steam exceeding the predetermined amount is generated by an electric boiler, the electric boilers can be operated continuously to generate the predetermined amount of steam, and electric power can be used more effectively.

[0008] The predetermined steam volume is a base steam volume determined from the steam usage volume in the facility in which the plurality of boilers are installed. According to the above configuration, the predetermined amount of steam is set as the base amount of steam, so that electric power can be used more effectively.

[0009] Further, the predetermined steam amount is a steam amount that can be changed based on information on power available in the plurality of boilers.

[0010] According to the above configuration, the predetermined steam amount can be varied based on the power information, and the electric boiler can be operated within the usable range.

[0011] Furthermore, when starting the plurality of boilers, the control unit starts the fuel boiler until the steam pressure reaches the predetermined value, while limiting the number of the plurality of electric boilers to be started.

[0012] According to the above configuration, the amount of power consumed by the electric boiler when the boiler is started can be limited.

[0013] Furthermore, when starting the plurality of boilers, the control unit starts the fuel boiler without starting any of the plurality of electric boilers until the steam pressure reaches the predetermined value.

[0014] According to the above configuration, by reducing the amount of power consumed by the electric boiler when the boiler is started up, the amount of power consumed can be used to generate a predetermined amount of steam after the steam pressure reaches a predetermined value.

[0015] Furthermore, when starting up the plurality of boilers, the control unit starts up some of the plurality of fuel boilers until the steam pressure reaches the predetermined value.

[0016] According to the above configuration, it is possible to suppress heat radiation from fuel boilers that are started in an excessive number and then stopped after the header pressure is increased. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram for explaining a schematic configuration of a boiler system. [Figure 2] 4 is a flowchart for explaining a boiler control process performed by the unit number control device. [Figure 3] FIG. 4 is a diagram showing an example of a base steam amount and a fluctuating steam amount. DETAILED DESCRIPTION OF THE INVENTION

[0018] <Overview of the configuration> Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, a schematic configuration of a boiler system 1 according to this embodiment will be described with reference to Fig. 1. As shown in Fig. 1, the boiler system 1 includes a plurality of boilers 2, a steam header 4 connected to each of the plurality of boilers 2 via a steam pipe 3, a steam pressure sensor 5 that measures the pressure value inside the steam header 4 (hereinafter also referred to as "header pressure value"), and a unit number control device 8 that controls the combustion state of each of the plurality of boilers 2.

[0019] The multiple boilers 2 include multiple electric boilers 2A that generate steam using Joule heat generated by electricity, and a fuel boiler 2B that generates steam by burning fuel (gas, liquid fuel, etc.). Each of the multiple electric boilers can be controlled to an operating state in which, when activated, it generates a predetermined amount of steam (for example, 500 kg / h). Each of the multiple electric boilers can be switched between an operating state and a stopped state (standby state).

[0020] Each of the plurality of fuel-fired boilers can be controlled to one of a plurality of combustion states in which the combustion amount (load factor) in the boiler body differs in stages. The plurality of combustion states include, for example, a low combustion state (an example of a first combustion position) in which the steam generation amount is a predetermined amount (e.g., 500 kg / h) and a high combustion state (an example of a second combustion position) in which the steam generation amount is a specific amount (e.g., 1000 kg / h). Each of the plurality of fuel-fired boilers can be switched to one of the high combustion state, the low combustion state, and a combustion-stop state (combustion standby).

[0021] In this embodiment, an example is shown in which the amount of steam generated when the electric boiler 2A is operating is the same as the amount of steam generated when the fuel boiler 2B is in a low combustion state, and the amount of steam generated when the electric boiler 2A is operating is the same as the difference between the amount of steam generated when the fuel boiler 2B is in a low combustion state and the amount of steam generated when the fuel boiler 2B is in a high combustion state, but this is not limiting and each may be set to a different amount.

[0022] The steam generated by each of the multiple boilers 2 is sent to a steam header 4 via steam piping 3. The steam header 4 collects the steam generated by each of the multiple boilers 2 and supplies the steam to a user facility 11 that uses the steam via a supply pipe 10. The steam pressure sensor 5 transmits a steam pressure signal for identifying the measured header pressure value to the unit count control device 8 via a signal line 6.

[0023] The number of units control device 8 includes a first number of units control device 8A that controls the states of multiple electric boilers and a second number of units control device 8B that controls the states of multiple fuel-fired boilers. The first number of units control device 8A transmits control signals for controlling each of the multiple electric boilers 2A via signal line 9A. Each of the multiple electric boilers 2A is controlled to be in a state (operating, stopped, etc.) specified by the received control signal. The second number of units control device 8B transmits control signals for controlling each of the multiple fuel-fired boilers 2B via signal line 9B. Each of the multiple fuel-fired boilers 2B sets a combustion state specified by the received control signal and controls the boiler to be in that combustion state. In addition, each of the multiple boilers 2 transmits a boiler body pressure signal for specifying the pressure value inside the boiler body to the first number of units control device 8A and the second number of units control device 8B, which are the control sources, via signal line 9.

[0024] The first unit count control device 8A and the second unit count control device 8B control the state of each of the multiple boilers 2 so that the header pressure value determined from the steam pressure signal falls within a predetermined pressure range or is constant at a predetermined target pressure, and supply steam to the usage equipment 11.

[0025] In this embodiment, the first number control device 8A and the second number control device 8B prioritize operation of the fuel boiler 2B over the electric boiler 2A when all of the boilers 2 are operated (powered on, combustion started, etc.) from a cold state (powered off, combustion stopped (combustion standby), etc.). This prevents a sudden increase in the amount of power consumed by the electric boiler 2A compared to when the electric boiler 2A is operated with priority over the fuel boiler 2B.

[0026] In addition, in this embodiment, the first number control device 8A and the second number control device 8B basically operate the fuel boiler 2B over the electric boiler 2A from the start of operation until the pressure value inside the steam header 4 reaches a predetermined value, but after the pressure value inside the steam header 4 reaches the predetermined value, they control the generation of a predetermined amount of steam (a base steam amount, described later) by the multiple electric boilers 2A, and the generation of a steam amount (a variable steam amount, described later) that is insufficient for the predetermined steam amount when the amount of steam used by the usage equipment 11 in the facility in which the boilers are installed exceeds the predetermined steam amount by the multiple fuel boilers 2B.

[0027] FIG. 2 is a flowchart illustrating the boiler control process performed by the number-of-units control device 8. The first number-of-units control device 8A and the second number-of-units control device 8B each repeatedly execute the boiler control process at predetermined intervals (e.g., 10 seconds). In step S01, for example, it is determined whether it is time to start the operation of multiple boilers from a cold state. If it is determined that the boilers are already operating and it is not time to start them from a cold state, the process proceeds to step S05. On the other hand, if it is determined that it is time to start the operation of multiple boilers from a cold state, the process proceeds to step S02, in which the second number-of-units control device 8B transmits an operation signal to a predetermined number of fuel-fired boilers. The predetermined number may be all fuel-fired boilers, a number (a portion of the number of boilers) required to generate the required amount of steam, or a predetermined number (a portion of the number of boilers) required to generate a predetermined amount of steam. This can suppress heat radiation from fuel-fired boilers that are shut down after the header pressure is increased. In this embodiment, since the operation of the electric boiler is restricted when a plurality of boilers are started from a cold state, an operation signal is not sent from the first number control device 8A to the electric boiler in step S02.

[0028] In step S03, it is determined whether the pressure value inside the steam header 4 has reached a predetermined value. The predetermined value is a value when at least steam can be supplied, and is a value that can be individually set based on the amount of steam used in the facility, and may be, for example, the lower limit of the pressure control range, a pressure value corresponding to the generation of a base steam amount, or a pressure value corresponding to the generation of the sum of the base steam amount and a predicted fluctuating steam amount. The determination in step S03 is repeated until it is determined that the predetermined value has been reached. When it is determined that the predetermined value has been reached, the process proceeds to step S04, in which the restriction on the operation of the electric boiler by the first number control device 8A is released, and in step S05, the operation state (including the combustion state) of the fuel boiler 2B is controlled according to the pressure value inside the steam header 4.

[0029] Next, in step S06, the first quantity control device 8A transmits an operation signal to start operation of the number of electric boilers 2A that will generate the set base steam amount from the cold state, thereby starting preparations for generating the base steam amount by the electric boilers.

[0030] The base steam volume is a base steam volume determined (calculated) from the amount of steam used in a facility. FIG. 3 is a diagram illustrating an example of the base steam volume. In FIG. 3, the horizontal axis represents time (e.g., from midnight to midnight), and the vertical axis represents the amount of steam used in the facility. The wavy lines in FIG. 3 represent an example of the actual amount of steam used in the facility by hour, showing that the actual amount of steam used in the facility varies depending on the time of day, as indicated by the wavy lines in FIG. 3. As shown in FIG. 3, the actual amount of steam used in the facility varies depending on the time of day, the day of the week, the weather, the season, and the like. The base steam volume is the amount of steam generated by the electric boiler, which is less than the actual amount of steam used, which can vary in this way. More specifically, the base steam volume is a value manually input by an operator that is deemed appropriate based on the actual amount of steam used and changes in the steam load, or a value that is preset depending on the time of day, the day of the week, the weather, the season, and the like. The value can vary in steps depending on the time of day, as shown in FIG. 3. The base steam volume is set to a value equal to or less than the volume of steam that can be generated by operating the electric boiler 2, within the range of power available in the facility. In steps S05 and S06, the base steam volume is generated by the electric boiler 2A, and the variable steam volume (see FIG. 3), which is the difference between the actual steam volume used and the base steam volume, is generated by the fuel boiler 2B, thereby making it possible to supply the volume of steam used in the facility. In step S05, the control of the operating state of the fuel boiler 2B may be transitioned when it is determined in step S06 that an average time (e.g., three minutes) required for the electric boiler 2A operated to become capable of steam generation (to be able to generate steam) has elapsed, or the operating state of the fuel boiler 2B may be controlled according to the volume of steam generated by the operation of the electric boiler 2A.

[0031] In step S07, it is determined whether a condition for changing the base steam volume is satisfied. The condition for changing the base steam volume may be satisfied, for example, when an operator manually re-enters a value deemed appropriate, when a preset value changes depending on the time of day, day of the week, weather, season, or the like, or when a control signal from the power demand monitoring device 12 (described later) is received. If it is determined in step S07 that the condition for changing the base steam volume is not satisfied, the boiler control process is terminated. On the other hand, if it is determined in step S07 that the condition for changing the base steam volume is satisfied, in step S08, the first quantity control device 8A transmits an operation signal for operating the number of electric boilers 2A required to generate the changed base steam volume. This initiates preparations for the electric boilers to generate the changed base steam volume, and the operation state of the fuel boiler 2B is controlled in step S05 according to the steam generation rate.

[0032] According to the number of units control device 8 in the above embodiment, after the steam pressure reaches a predetermined value from the start of operation, the base steam amount is generated by the electric boiler 2A, and any fluctuating steam amount exceeding the base steam amount is generated by the fuel boiler 2B, as shown in steps S05 to S08 in Fig. 2. Therefore, compared to generating fluctuating steam amounts exceeding the base steam amount by the electric boiler, the electric boiler can be operated continuously to generate the base steam amount, allowing for more effective use of electricity.

[0033] 2, from the start of operation until the steam pressure reaches a predetermined value, the fuel boiler 2B is operated while the electric boiler 2A is not operated. This makes it possible to limit the amount of power consumed by the electric boiler when starting up the boilers, and to use the power consumed to generate a base amount of steam after the steam pressure reaches the predetermined value.

[0034] The base steam flow rate can also be changed by a control signal from the power demand monitoring device 12. An example of this is described below. The first number of units control device 8A and the second number of units control device 8B control the state of each of the multiple boilers 2 by a control signal from the power demand monitoring device 12, even if the header pressure value is a value that does not require a change in the state of each of the multiple boilers 2. The first number of units control device 8A and the second number of units control device 8B each include at least a steam pressure acquisition unit that acquires the header pressure value and the boiler body pressure value from each boiler, a power information acquisition unit that acquires the control signal from the power demand monitoring device 12, and a control unit that controls each of the multiple boilers based on the steam pressure, the control signal from the power demand monitoring device 12, etc.

[0035] The power demand monitoring device 12 corresponds to a so-called aggregator, and for example, provides support for controlling the multiple boilers 2 so that the amount of power used in a facility such as a factory in which the boiler system 1 is installed does not exceed the contracted power amount as much as possible and converges to the contracted power amount. Note that the power demand monitoring device 12 may be included in the boiler system 1, but is not limited to this, and may be located within the same facility without being included in the boiler system 1, or may be located outside the facility.

[0036] The power demand monitoring device 12 transmits a control signal (hereinafter also referred to as a downward DR request signal) to the first number of units control device 8A and the second number of units control device 8B to perform a downward demand response (hereinafter also referred to as a downward DR request signal) requesting a reduction in power demand when, for example, the amount of power usage after a predetermined time (e.g., 30 minutes) is likely (predicted) to exceed the contracted power amount, taking into account the power used by equipment other than the electric boiler in the facility and the power generated in the facility. The downward DR request signal is a signal that includes information specifying, for example, the amount of power requested to be reduced (or the amount of power exceeding the contracted power amount) and the start time of the downward DR. In response to the downward DR request signal, the first number of units control device 8A and the second number of units control device 8B reduce the amount of steam generated by the electric boiler 2A (e.g., base steam amount) and increase the amount of steam generated by the fuel boiler 2B.

[0037] Furthermore, the power demand monitoring device 12 transmits a control signal (hereinafter also referred to as an "upward DR request signal") to the first number of units control device 8A and the second number of units control device 8B to perform an upward demand response (hereinafter also referred to as an "upward DR") requesting an increase in power demand when, for example, the amount of power usage after a predetermined time is likely to fall below the contracted amount, taking into account the power used by equipment other than the electric boiler and the power generated within the facility. The upward DR request signal is a signal that includes information specifying, for example, the amount of power requested to be increased (or the amount of power below the contracted amount) and the start time of the upward DR. In response to the upward DR request signal, the first number of units control device 8A and the second number of units control device 8B increase the amount of steam generated by the electric boiler 2A (e.g., base steam amount) and decrease the amount of steam generated by the fuel boiler 2B. In this way, by varying the base steam amount based on the power information of the downward DR request signal or the upward DR request signal, the electric boiler can be operated within the range of available power.

[0038] The present invention is not limited to the above-described embodiment, and various modifications and applications are possible. Modifications of the above-described embodiment that can be applied to the present invention will be described below.

[0039] In the above-described embodiment, as shown in steps S01 to S04 of FIG. 2, an example has been given in which the fuel boiler 2B is operated while the electric boiler 2A is not operated from the start of operation until the steam pressure reaches a predetermined value. However, this is not limited to this, as long as the fuel boiler 2B is operated with priority over the electric boiler 2A and the number of electric boilers 2A in operation is limited, and the number of electric boilers 2A in operation may be limited to a predetermined number (for example, two), and a predetermined number of electric boilers 2A may be operated.

[0040] In the above-described embodiment, as shown in step S06 of FIG. 2 , the predetermined steam volume to be generated by the electric boiler after the steam pressure reaches a predetermined value is a base steam volume manually input by an operator as deemed appropriate, or a base steam volume preset based on the time period, day of the week, weather, season, etc. However, the predetermined steam volume is not limited to this. It may also be a steam volume periodically calculated based on the operating status of the steam-using equipment. The calculated steam volume may be transmitted to the number-of-units control device via communication, and the number-of-units control device may rewrite the parameters for specifying the predetermined steam volume stored internally with the received steam volume. Alternatively, the number-of-units control device may store several patterns for specifying the base steam volume in advance, select an optimal pattern via signals or communication depending on the operating status of the steam-using equipment, and specify the base steam volume from that pattern. Alternatively, the number-of-units control device may be provided with a scheduling function that registers parameters for each day of the week, date, and time period (e.g., registering values ​​for one week at the beginning of each week), and specify the base steam volume based on the registered parameters.

[0041] In the boiler system 1 of the above embodiment, an example has been described in which two or more electric boilers and two or more fuel boilers are included, but the system is not limited to this and may include at least one electric boiler and one or more fuel boilers. Also, while the number of units control device has been exemplified by a first number of units control device for electric boilers and a second number of units control device for fuel boilers, the system is not limited to this and may be controlled by a single number of units control device shared by both electric boilers and fuel boilers.

[0042] In addition, while the electric boiler has been described as being controllable between an operating state and a stopped state, it is not limited to this, and may be controllable to a plurality of operating states with different steam generation rates, or may be controllable to a pressure-maintaining operating state that maintains the state immediately before steam generation.In addition, the fuel boiler has been described as being controllable to any of a high combustion state, a low combustion state, and a combustion-stopped state, but it is not limited to this, and may be controllable to a medium combustion state.

[0043] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0044] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] This disclosure also includes matters that contribute to achieving Goal 12 of the SDGs (Sustainable Development Goals), "Responsible Consumption and Production," and Goal 13, "Take urgent action to combat climate change." [Explanation of symbols]

[0045] 1. Boiler system 2A electric boiler 2B fuel boiler 3 Steam piping 4 Steam header 5 Vapor pressure sensor 6 Signal Line 8A First unit control device 8B First Numerical Control Device 9 Signal Line 10 Supply Pipe 11 Equipment in Use 12 Power Demand Monitoring Device

Claims

1. A unit number control device for controlling a plurality of boilers including a plurality of fuel boilers and a plurality of electric boilers, a steam pressure acquisition unit that acquires steam pressures of steam generated in the plurality of boilers; a control unit that controls the plurality of boilers based on the steam pressure, The control unit controls the plurality of electric boilers to generate a predetermined amount of steam after the steam pressure reaches a predetermined value, and controls the plurality of fuel boilers to generate an amount of steam exceeding the predetermined amount of steam.

2. The unit count control device according to claim 1 , wherein the predetermined steam volume is a base steam volume determined from a steam usage volume in a facility in which the plurality of boilers are installed.

3. The unit number control device according to claim 1 , wherein the predetermined steam amount is a steam amount that can be varied based on information about electric power available in the plurality of boilers.

4. 2. The unit count control device according to claim 1, wherein, when starting the plurality of boilers, the control unit starts the fuel boiler until the steam pressure reaches the predetermined value, while limiting the number of the plurality of electric boilers that are started.

5. 5. The unit number control device according to claim 4, wherein when starting the plurality of boilers, the control unit starts the fuel boiler without starting any of the plurality of electric boilers until the steam pressure reaches the predetermined value.

6. The unit number control device according to claim 4 , wherein, when starting the plurality of boilers, the control unit keeps some of the plurality of fuel-fired boilers running until the steam pressure reaches the predetermined value.

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