JP7653863B2 - Boiler Control System - Google Patents

Description

The present invention relates to a boiler control system that includes multiple boilers.

In a boiler control system where multiple boilers are installed, the steam pipes of each boiler are connected to a steam header, and steam is supplied from the steam header to the steam utilization equipment. The steam header is equipped with a pressure sensor, and controls the boiler load to be increased when the pressure drops, and decreased when the pressure rises.

In a boiler control system, the combustion position of each boiler is determined to improve energy efficiency while ensuring the amount of steam required by the steam utilization facility. For example, in the boiler control system shown in Patent Document 1, the pressure control band that serves as the basis for switching the combustion position is switched based on the average load.

JP 2021-32469 A

There is a demand for further improvements in energy efficiency in boiler control systems where multiple boilers are installed.

The present invention aims to provide a boiler control system that can improve energy efficiency.

In order to solve the above problems, the boiler control system of the present invention includes a boiler group including a plurality of boilers, and a control device in which a plurality of combustion patterns are stored that define the operating load of each of the plurality of boilers for each total load of the boiler group, and that controls the operating load of the boilers based on the combustion pattern, wherein the plurality of combustion patterns differ from one another in terms of the number of operating boilers defined for at least some of the total loads, and the control device derives an average load of the boiler group for a predetermined period including a plurality of sections , and determines one of the plurality of combustion patterns based on the derived average load, and if the average load of one section included in the predetermined period differs from the average load of other sections included in the predetermined period by more than a predetermined value, makes the combustion pattern of the one section different from the combustion pattern of the other sections, and determines the operating load of each of the plurality of boilers for the next predetermined period based on the determined combustion pattern and the total load.

In addition, the multiple combustion patterns may be linked to the boiler's feedwater temperature, and the control device may determine the combustion pattern based on the average load and the feedwater temperature.

The present invention can improve energy efficiency.

FIG. 2 is a diagram illustrating a boiler control system. FIG. 4 is a diagram illustrating a combustion position. FIG. 4 is a diagram illustrating an example of a normal combustion pattern. FIG. 13 is a diagram illustrating an example of a three-unit combustion pattern. FIG. 13 is a diagram illustrating an example of a two-unit combustion pattern. FIG. 11 is a diagram illustrating an example of a single-unit combustion pattern. FIG. 13 is a diagram illustrating the relationship between the average load and the combustion pattern when the feed water temperature is 15° C. FIG. 13 is a diagram illustrating the relationship between the average load and the combustion pattern when the feed water temperature is 60° C. FIG. 4 is a diagram illustrating the relationship between the feed water temperature, the boiler load factor, and the boiler efficiency. FIG. 2 is a functional block diagram of the boiler control system. 4 is a flowchart illustrating a process of a number-of-units control device. 4 is a flowchart illustrating a combustion pattern update process. 4 is a flowchart illustrating a boiler control process.

The preferred embodiment of the present invention will be described in detail below with reference to the attached drawings. The dimensions, materials, and other specific values shown in the embodiment are merely examples to facilitate understanding of the invention, and do not limit the present invention unless otherwise specified. In this specification and drawings, elements that have substantially the same function and configuration are given the same reference numerals to avoid duplicated explanations, and elements that are not directly related to the present invention are not illustrated.

Figure 1 is a diagram illustrating a boiler control system S. The boiler control system S includes a boiler group including a plurality of boilers. Here, as an example, the boiler control system S includes a boiler group including four boilers, a first boiler 1, a second boiler 2, a third boiler 3, and a fourth boiler 4. However, it is sufficient that a plurality of boilers are provided, and the number of boilers is not particularly limited.

The first boiler 1 is equipped with a first boiler control device 1A. Similarly, the second boiler 2, the third boiler 3, and the fourth boiler 4 are equipped with a second boiler control device 2A, a third boiler control device 3A, and a fourth boiler control device 4A, respectively. Hereinafter, the first boiler control device 1A, the second boiler control device 2A, the third boiler control device 3A, and the fourth boiler control device 4A are collectively referred to as the boiler control devices. The boiler control devices control the operation of each boiler.

The first boiler 1, the second boiler 2, the third boiler 3, and the fourth boiler 4 are connected to feedwater pipes 1a, 2a, 3a, and 4a, respectively. The feedwater pipes 1a, 2a, 3a, and 4a are connected to a main feedwater pipe 5. The main feedwater pipe 5 is connected to a water supply source (not shown). Therefore, the first boiler 1, the second boiler 2, the third boiler 3, and the fourth boiler 4 are supplied with water from the water supply source via the feedwater pipes 1a, 2a, 3a, and 4a and the main feedwater pipe 5, respectively.

A feedwater pump P is provided on each of the feedwater pipes 1a, 2a, 3a, and 4a. The boiler control device controls the feedwater pump P to change the amount of feedwater supplied from the feedwater source to each boiler. Specifically, the first boiler control device 1A controls the feedwater pump P provided on the feedwater pipe 1a to adjust the amount of water supplied to the first boiler 1. Similarly, the second boiler control device 2A, the third boiler control device 3A, and the fourth boiler control device 4A control the feedwater pumps P provided on the feedwater pipes 2a, 3a, and 4a, respectively, to adjust the amount of water supplied to the second boiler 2, the third boiler 3, and the fourth boiler 4.

A temperature sensor 6 is provided in the main water supply pipe 5. The temperature sensor 6 measures the temperature of the water in the main water supply pipe 5. Hereinafter, the temperature of the water measured by the temperature sensor 6 will be referred to as the feedwater temperature. The temperature sensor 6 is connected to the unit count control device 100. A signal indicating the feedwater temperature measured by the temperature sensor 6 is input to the unit count control device 100. The unit count control device 100 mainly determines the combustion position of each boiler.

Fuel supply pipes 1b, 2b, 3b, and 4b are connected to the first boiler 1, the second boiler 2, the third boiler 3, and the fourth boiler 4, respectively. The fuel supply pipes 1b, 2b, 3b, and 4b are connected to a fuel main pipe 7. The fuel main pipe 7 is connected to a fuel source (not shown). Therefore, fuel is supplied from the fuel source to the first boiler 1, the second boiler 2, the third boiler 3, and the fourth boiler 4, respectively, via the fuel supply pipes 1b, 2b, 3b, and 4b and the fuel main pipe 7.

The fuel supply pipes 1b, 2b, 3b, and 4b are each provided with a flow control valve V. The flow control valve V is configured as an electric valve and is controlled by the boiler control device. The boiler control device changes the amount of fuel supplied from the fuel source to each boiler by controlling the opening degree of the flow control valve V. Specifically, the first boiler control device 1A controls the flow control valve V provided in the fuel supply pipe 1b to adjust the amount of fuel supplied to the first boiler 1. Similarly, the second boiler control device 2A, the third boiler control device 3A, and the fourth boiler control device 4A control the flow control valve V provided in the fuel supply pipes 2b, 3b, and 4b, respectively, to adjust the amount of fuel supplied to the second boiler 2, the third boiler 3, and the fourth boiler 4.

The first boiler 1, the second boiler 2, the third boiler 3, and the fourth boiler 4 each include a combustion device (not shown). In addition, here, city gas is supplied to each boiler as an example of fuel. However, the fuel is not limited to city gas, and any fuel that can achieve a combustion action in each boiler may be used. The fuel may be either gas or liquid, and in particular, when the fuel is gas, a mixture of air and fuel may be supplied.

Here, each boiler uses a combustion device to burn fuel supplied from a fuel source, and generates steam by heating feedwater with the heat of combustion. The boiler control device controls the amount of steam generated in each boiler, i.e., the load of each boiler, by controlling the feedwater pump P and flow control valve V.

However, each boiler only needs to be capable of heating the feed water to generate steam, and the specific configuration is not particularly limited. For example, each boiler may be equipped with an electric heater.

The first boiler 1, the second boiler 2, the third boiler 3, and the fourth boiler 4 are connected to a steam header 8 via steam pipes 1c, 2c, 3c, and 4c, respectively. The steam header 8 is also connected to a steam utilization facility 9, in which the steam is utilized, via a steam supply pipe 8a. Therefore, the steam generated in each boiler is supplied to the steam utilization facility 9 via the steam header 8.

The steam header 8 is provided with a pressure sensor 10, and the pressure of the steam header 8 detected by the pressure sensor 10 is input to the number-of-units control device 100. Hereinafter, the pressure of the steam header 8 is referred to as the steam header pressure. The number-of-units control device 100 controls the combustion position of each boiler based on the feedwater temperature of the water supplied to each boiler, the load history of each boiler, the steam header pressure of the steam header 8, etc.

Figure 2 is a diagram explaining the combustion positions. Here, as an example, four combustion positions are provided for each boiler: high combustion position (High), medium combustion position (Mid), low combustion position (Low), and stop position (Stop). The number of units control device 100 determines one of the four combustion positions for each boiler. The boiler control device controls the feedwater pump P and the flow control valve V based on the combustion position determined by the number of units control device 100. In other words, the number of units control device 100 can be said to be a higher-level control device than the boiler control devices provided for each boiler.

The high combustion position is the combustion position for rated operation, and here the boiler load in the high combustion position is taken to be 100%. The medium combustion position produces less steam than the high combustion position, and the load is 50% of that in rated operation. In other words, the amount of steam produced in the medium combustion position is approximately 50% of that in the high combustion position.

The low combustion position produces less steam than the medium combustion position, and the load is 20% of rated operation. In other words, the amount of steam produced in the low combustion position is approximately 20% of that in the high combustion position. The stopped position is a boiler stopped state in which no steam is produced, and the load is 0%. The stopped position may be a completely stopped state in which the spark in the combustion device has been extinguished, or it may be a pilot state in which the spark remains.

As mentioned above, the operating load of each boiler is determined by its combustion position, so the combustion position can also be considered the operating load. Here, the combustion position of each boiler is set based on the combustion pattern. The combustion pattern defines the operating load of each of the multiple boilers for each total load of the boiler group. In other words, the combustion pattern defines the combustion position of each of the first boiler 1, second boiler 2, third boiler 3, and fourth boiler 4 according to the steam load required by the steam utilization facility 9.

Figure 3 is a diagram explaining an example of a normal combustion pattern. Figure 4 is a diagram explaining an example of a three-unit combustion pattern. Figure 5 is a diagram explaining an example of a two-unit combustion pattern. Figure 6 is a diagram explaining an example of a one-unit combustion pattern. Here, multiple combustion patterns are prepared in advance. The combustion patterns are basically classified into one of the following: a normal combustion pattern shown in Figure 3, which is based on the assumption that four boilers are operated; a three-unit standard combustion pattern shown in Figure 4, which is based on the assumption that three boilers are operated; a two-unit standard combustion pattern shown in Figure 5, which is based on the assumption that two boilers are operated; and a one-unit standard combustion pattern shown in Figure 6, which is based on the assumption that one boiler is operated. Note that the operation of a boiler refers to a state in which the boiler is set to one of the high, medium, or low combustion positions, i.e., a state in which the boiler is set to a combustion position other than the stop position.

In addition, there are multiple normal combustion patterns, 3-unit standard combustion patterns, 2-unit standard combustion patterns, and 1-unit standard combustion patterns, each of which is provided according to the feedwater temperature. As an example, Figs. 3 to 6 show a combustion pattern that is adopted when the feedwater temperature is around 15°C, and a combustion pattern that is adopted when the feedwater temperature is around 60°C. For convenience of explanation, the combustion patterns for feedwater temperatures of 15°C and 60°C will be explained here, but combustion patterns corresponding to other temperatures are also provided.

In Figures 3 to 6, "H" indicates a high combustion position, "M" indicates a medium combustion position, "L" indicates a low combustion position, and "S" indicates a stop position. Here, the maximum output of each boiler, i.e., the load of each boiler when set to the high combustion position, is 2t/h. Therefore, the maximum total load of the boiler group having four boilers, the first boiler 1, the second boiler 2, the third boiler 3, and the fourth boiler 4, is 8t/h.

For example, as shown in the upper diagram of Figure 3, assume that the feedwater temperature is around 15°C and the normal combustion pattern is adopted. As shown in the bold box in the diagram, when pressure control is performed using this normal combustion pattern and all four boilers are set to the low combustion position, the total load per hour is approximately 1.2 tons or more and less than 1.6 tons. Also, when the first boiler 1 is set to the medium combustion position and the second boiler 2, third boiler 3, and fourth boiler 4 are set to the low combustion position, the total load per hour is approximately 1.6 tons or more and less than 2.2 tons.

For example, as shown in the lower diagram of Figure 3, assume that the feedwater temperature is around 60°C and the normal combustion pattern is adopted. As shown in the bold box in the figure, when pressure control is performed using this normal combustion pattern and all four boilers are set to the medium combustion position, the total load per hour is approximately 3.4t or more and less than 4.0t. Also, when the first boiler 1, second boiler 2, and third boiler 3 are set to the medium combustion position and the fourth boiler 4 is set to the low combustion position, the total load per hour is approximately 3.0t or more and less than 3.4t.

In this way, in each combustion pattern, the total load of the boiler group is determined by the combustion position of each of the multiple boilers. In other words, each combustion pattern determines the combustion position of each boiler for each total load of the boiler group. The number control device 100 determines the combustion pattern in advance, and then, for a predetermined period of time, the combustion position of each boiler is controlled based on the determined combustion pattern.

Specifically, load information indicating the load on the steam utilization equipment 9 is input to the unit count control device 100. The unit count control device 100 stores the input load information and derives the average load for each specified period. The average load is the steam load per hour. Here, as an example, one week is set as the specified period, and the unit count control device 100 derives the average load at midnight on Monday, for example, by averaging the load from midnight on the previous Monday to midnight on the following Monday. Then, based on the derived average load and the feedwater temperature, the unit count control device 100 selects one combustion pattern to be adopted for the next week from among multiple combustion patterns.

When selecting a combustion pattern, the unit count control device 100 may obtain the feed water temperature from the temperature sensor 6, or, similar to the average load, may obtain the average feed water temperature for the most recent week. Alternatively, the unit count control device 100 may predict the feed water temperature for the next week based on weather information, etc., and obtain the predicted feed water temperature.

In addition, while the combustion patterns are exemplified here when the feed water temperature is 15°C or 60°C, the feed water temperature intervals at which the combustion patterns are provided are not particularly limited. Combustion patterns may be provided at intervals of 5 degrees or 10 degrees, for example. The unit count control device 100 selects, from the provided combustion patterns, the combustion pattern that corresponds to the feed water temperature that is closest to the acquired feed water temperature.

Figure 7 is a diagram explaining the relationship between the average load and the combustion pattern when the feed water temperature is 15°C. Figure 8 is a diagram explaining the relationship between the average load and the combustion pattern when the feed water temperature is 60°C. Here, the number-of-units control device 100 determines the combustion pattern to be adopted for the next week based on the average load for the most recent week and the feed water temperature input from the temperature sensor 6.

As shown in FIG. 7, for example, if the feedwater temperature is around 15°C and the average load for the most recent week is less than 0.8 t/h, the unit count control device 100 selects the standard 1-unit combustion pattern for 15°C as the combustion pattern for the following week. Similarly, if the average load for the most recent week is 0.8 t/h or more and less than 1.2 t/h, the unit count control device 100 selects the standard 2-unit combustion pattern for 15°C. If the average load for the most recent week is 1.2 t/h or more and less than 1.6 t/h, the unit count control device 100 selects the standard 3-unit combustion pattern for 15°C. If the average load for the most recent week is 1.6 t/h or more, the unit count control device 100 selects the normal combustion pattern for 15°C.

Also, as shown in FIG. 8, for example, if the feedwater temperature is around 60°C and the average load for the most recent week is less than 1.4 t/h, the unit count control device 100 selects the 1-unit standard combustion pattern for 60°C as the combustion pattern for the following week. Similarly, if the average load for the most recent week is 1.4 t/h or more and less than 2.4 t/h, the unit count control device 100 selects the 2-unit standard combustion pattern for 60°C. If the average load for the most recent week is 2.4 t/h or more and less than 3.4 t/h, the unit count control device 100 selects the 3-unit standard combustion pattern for 60°C. If the average load for the most recent week is 3.4 t/h or more, the unit count control device 100 selects the normal combustion pattern for 60°C.

As mentioned above, here, the combustion patterns are classified into the normal combustion pattern, the 3-unit standard combustion pattern, the 2-unit standard combustion pattern, and the 1-unit standard combustion pattern. Each of these four combustion patterns has a different number of basic boilers in operation. The smaller the average load over the past week, the fewer the basic boilers in operation are selected, and the higher the average load over the past week, the more the basic boilers in operation are selected. As a result, if there is no large change in the average load per week between the previous week and this week, the combustion position is set to maximize the boiler efficiency.

For example, as shown in FIG. 7, assume that the average load over the past week was 1.6 t/h or more and the feed water temperature was 15°C. In this case, the normal combustion pattern for 15°C is selected as the combustion pattern for the next week. Also, as shown in FIG. 8, assume that the average load over the past week was 3.4 t/h or more and the feed water temperature was 60°C. In this case, the normal combustion pattern for 60°C is selected as the combustion pattern for the next week.

As shown in the upper diagram of Figure 3, in the normal combustion pattern for 15°C, the combustion positions of each boiler are set for each total load so that four boilers will operate when the total load is 1.6 t/h or more. On the other hand, as shown in the lower diagram of Figure 3, in the normal combustion pattern for 60°C, the combustion positions of each boiler are set for each total load so that four boilers will operate when the total load is 3.4 t/h or more.

In other words, in the normal combustion pattern, when the total load is equal to or greater than the average load threshold (1.6 t/h or 3.4 t/h) for which the normal combustion pattern is selected, the combustion position of each boiler is set so that the number of boilers in operation is always four.

As shown in FIG. 7, assume that the average load for the most recent week was 1.2 t/h or more and less than 1.6 t/h, and the feed water temperature was 15°C. In this case, the three-unit standard combustion pattern for 15°C is selected as the combustion pattern for the next week. As shown in FIG. 8, assume that the average load for the most recent week was 2.4 t/h or more and less than 3.4 t/h, and the feed water temperature was 60°C. In this case, the three-unit standard combustion pattern for 60°C is selected as the combustion pattern for the next week.

As shown in the thick-line box in the upper diagram of Figure 4, in the standard three-unit combustion pattern for 15°C, the combustion positions are set so that three boilers will operate when the total load is 0.8 t/h or more and less than 1.8 t/h. Also, as shown in the thick-line box in the lower diagram of Figure 4, in the standard three-unit combustion pattern for 60°C, the combustion positions are set so that three boilers will operate when the total load is 2.0 t/h or more and less than 3.0 t/h.

As mentioned above, the 3-unit standard combustion pattern for 15°C is selected when the average load for the most recent week is 1.2 t/h or more and less than 1.6 t/h. The 3-unit standard combustion pattern for 60°C is selected when the average load for the most recent week is 2.4 t/h or more and less than 3.4 t/h. Therefore, in the 3-unit standard combustion pattern, the combustion positions of each boiler are set so that the number of boilers in operation is three when the total load is in the same range as the average load for the most recent week.

As shown in FIG. 7, assume that the average load over the past week was 0.8 t/h or more and less than 1.2 t/h, and the feed water temperature was 15°C. In this case, the two-unit standard combustion pattern for 15°C is selected as the combustion pattern for the next week. As shown in FIG. 8, assume that the average load over the past week was 1.4 t/h or more and less than 2.4 t/h, and the feed water temperature was 60°C. In this case, the two-unit standard combustion pattern for 60°C is selected as the combustion pattern for the next week.

As shown in the thick-line box in the upper diagram of Figure 5, in the standard two-unit combustion pattern for 15°C, the combustion positions are set so that two boilers are in operation when the total load is 0.4 t/h or more and less than 1.4 t/h. Also, as shown in the thick-line box in the lower diagram of Figure 5, in the standard two-unit combustion pattern for 60°C, the combustion positions are set so that two boilers are in operation when the total load is 1.0 t/h or more and less than 2.0 t/h.

As mentioned above, the two-unit standard combustion pattern for 15°C is selected when the average load for the most recent week is 0.8 t/h or more and less than 1.2 t/h. The two-unit standard combustion pattern for 60°C is selected when the average load for the most recent week is 1.4 t/h or more and less than 2.4 t/h. Therefore, in the two-unit standard combustion pattern, the combustion positions of each boiler are set so that the number of boilers in operation is two when the total load is in the same range as the average load for the most recent week.

As shown in FIG. 7, assume that the average load for the past week is less than 0.8 t/h and the feed water temperature is 15°C. In this case, the single-unit standard combustion pattern for 15°C is selected as the combustion pattern for the next week. As shown in FIG. 8, assume that the average load for the past week is less than 1.4 t/h and the feed water temperature is 60°C. In this case, the single-unit standard combustion pattern for 60°C is selected as the combustion pattern for the next week.

As shown in the thick-line box in the upper diagram of Figure 6, in the standard single-unit combustion pattern for 15°C, the combustion positions of each boiler are set for each total load so that one boiler operates when the total load is less than 1.0 t/h. Also, as shown in the thick-line box in the lower diagram of Figure 6, in the standard single-unit combustion pattern for 60°C, the combustion positions of each boiler are set for each total load so that one boiler operates when the total load is less than 1.0 t/h.

As mentioned above, the standard one-unit combustion pattern for 15°C is selected when the average load for the most recent week is less than 0.8 t/h. The standard one-unit combustion pattern for 60°C is selected when the average load for the most recent week is less than 1.4 t/h. Therefore, in the standard one-unit combustion pattern, the combustion position of each boiler is set so that when the total load is in the same range as the average load for the most recent week, there will be only one boiler in operation.

Here, the most efficient operating load, i.e., the most efficient boiler load rate, varies depending on the feedwater temperature.

Figure 9 is a diagram explaining the relationship between feedwater temperature, boiler load factor, and boiler efficiency. In Figure 9, the horizontal axis shows the boiler load factor, and the vertical axis shows the boiler efficiency. The upper graph in Figure 9 shows the relationship between the boiler load factor and boiler efficiency when the feedwater temperature is 15°C, and the lower graph in Figure 9 shows the relationship between the boiler load factor and boiler efficiency when the feedwater temperature is 60°C.

As shown in the upper diagram of Figure 9, when the feedwater temperature is 15°C, each boiler is most efficient when operated at a load of 20%, i.e., in the low combustion position. Furthermore, when the feedwater temperature is 15°C, operation in the medium combustion position is the second most efficient after operation in the low combustion position, and operation in the high combustion position is the least efficient of all the combustion positions.

In contrast, when the feedwater temperature is 60°C, each boiler is most efficient when it is operated at a load of about 50%, i.e., in the medium combustion position. Furthermore, when the feedwater temperature is 60°C, operation in the low combustion position is the second most efficient after operation in the medium combustion position, and operation in the high combustion position is the least efficient of all the combustion positions.

As mentioned above, the efficiency of each combustion position varies depending on the feedwater temperature, so the combustion position of each boiler is set so that the efficiency is highest in each combustion pattern. As mentioned above, the range surrounded by the thick lines in Figures 3 to 6 is a range equivalent to the average load for the most recent week. Therefore, for each boiler, the proportion of time that it is set to the combustion position surrounded by the thick lines in the selected combustion pattern is high.

As shown in Figures 3 to 6, in the combustion pattern for 15°C, many low combustion positions are set in the range enclosed by the thick line, and in the combustion pattern for 60°C, many medium combustion positions are set in the range enclosed by the thick line. In this way, in each combustion pattern, especially when the total load is in the same range as the average load for the most recent week, the combustion positions are set within a range that allows for a high efficiency for the feed water temperature.

Next, we will explain the functional configuration and control process of the boiler control system S.

Figure 10 is a functional block diagram of the boiler control system S. As shown in Figure 10, the boiler control system S includes a unit count control device 100. The unit count control device 100 includes a processor 101, a memory 102, and a storage 103. The processor 101 is an arithmetic processing device mounted on a computer. The processor 101 is, for example, configured as a CPU (Central Processing Unit), but may be configured as other microprocessors. The processor 101 may also be configured as one or more processors. The processor 101 performs various processes by executing programs stored in the memory 102 or other storage media.

The program is a computer program that includes instructions to be executed by a computer. The program may be provided to the unit count control device 100, for example, by distribution from an external device through a communication network. The program may also be provided to the unit count control device 100 via a non-transitory computer readable medium. By installing the program in the unit count control device 100, various functions defined by the program can be realized.

The memory 102 is a storage medium that stores programs and various other data. The memory 102 includes, for example, a RAM (Random Access Memory) and a ROM (Read Only Memory). The ROM is a non-volatile memory that stores programs used by the processor 101 and data for operating the programs. The RAM is a volatile memory that temporarily stores data such as variables, calculation parameters, and calculation results used in the processing executed by the processor 101. The programs stored in the ROM are read into the RAM and executed by the processor 101 such as a CPU. Note that, here, the combustion patterns shown in Figures 3 to 6 are stored in the memory 102.

Storage 103 is a storage device for storing various types of information and data. Storage 103 has a recording medium such as a semiconductor memory, a hard disk, or an optical disk, and a drive for reading data from the recording medium or writing data to the recording medium. Storage 103 can store a larger amount of data than memory 102. Storage 103 may be an internal storage built into unit control device 100, or an external storage connected via an external input/output terminal of unit control device 100. Storage 103 may also be an online storage connected via a communication network.

Although detailed explanation is omitted, the first boiler control device 1A, the second boiler control device 2A, the third boiler control device 3A, and the fourth boiler control device 4A each have a processor, memory, and storage 103, just like the number control device 100.

The processor 101 of the unit count control device 100 reads out the programs stored in the memory 102 and executes various processes, thereby functioning as a load information acquisition unit 101a, an average load derivation unit 101b, a combustion pattern determination unit 101c, and a boiler control unit 101d. The storage 103 also functions as a load history memory unit 103a, an average load memory unit 103b, a combustion pattern memory unit 103c, and a combustion position memory unit 103d.

As described above, the unit count control device 100 receives the feedwater temperature from the temperature sensor 6, the load information from the steam utilization equipment 9, and the steam header pressure from the pressure sensor 10. Furthermore, the unit count control device 100 is connected to a timing device 11, and date and time information is input from the timing device 11 to the unit count control device 100.

The load information acquisition unit 101a acquires load information from the steam utilization equipment 9 and stores it in the load history storage unit 103a.

When date and time information indicating midnight on Monday is input from the clock device 11, the average load derivation unit 101b derives the average load for the most recent week and stores it in the average load memory unit 103b.

The combustion pattern determination unit 101c determines a combustion pattern based on the average load stored in the average load memory unit 103b and the feed water temperature input from the temperature sensor 6, and stores it in the combustion pattern memory unit 103c.

The boiler control unit 101d outputs control signals to the first boiler control device 1A, the second boiler control device 2A, the third boiler control device 3A, and the fourth boiler control device 4A based on the combustion pattern stored in the combustion pattern memory unit 103c, the transition of the load information stored in the load history memory unit 103a, the steam header pressure, etc. Specifically, the boiler control unit 101d changes the combustion position of each boiler stored in the combustion position memory unit 103d. In addition, the boiler control unit 101d outputs a control signal instructing the boiler control device of the boiler whose combustion position has been changed to the changed combustion position. The boiler control device controls the feedwater pump P and the flow control valve V based on the received control signal. The control process of the number control device 100 is described below.

Figure 11 is a flowchart explaining the processing of the unit count control device 100. The processor 101 of the unit count control device 100 repeatedly executes the processing shown in Figure 11 at predetermined time intervals. The interval at which the processing shown in Figure 11 is executed is not particularly limited, and may be set within a range of several milliseconds to several minutes, for example. The processor 101 acquires date and time information from the timing device 11, and determines whether it is a predetermined date and time (S1).

Here, midnight on Monday is preset as the specified date and time, and it is determined whether the acquired date and time information is midnight on Monday. If it is determined that it is midnight on Monday (YES in S1), the processor 101 executes the combustion pattern update process (S100). Furthermore, the processor 101 executes the boiler control process (S200) regardless of whether it is the specified date and time or not.

Figure 12 is a flowchart explaining the combustion pattern update process (S100). In the combustion pattern update process, the processor 101 first acquires load information for the most recent week stored in the load history storage unit 103a (S101). The processor 101 also derives the average load from the acquired load information for the most recent week (S102).

The load history storage unit 103a stores the load per hour of the steam utilization equipment 9 at that time at intervals of several seconds to several minutes. The processor 101 derives the average load by dividing the total load stored in the load history storage unit 103a for the most recent week by the number of stored loads. The processor 101 then stores the derived average load in the average load storage unit 103b. As described above, the processor 101 executes the processes of S101 and S102 as the average load derivation unit 101b.

Next, the processor 101 acquires the current feed water temperature from the temperature sensor 6 (S103). The processor 101 then determines a combustion pattern based on the average load derived in S102 and the feed water temperature acquired in S103 (S104). The processor 101 also stores the determined combustion pattern in the combustion pattern storage unit 103c. Furthermore, the processor 101 stores the combustion position corresponding to the current load of the steam utilization equipment 9, i.e., the total load, in the combustion position storage unit 103d based on the determined combustion pattern. As described above, the processor 101 executes the processes of S103 and S104 as the combustion pattern determination unit 101c.

Figure 13 is a flowchart explaining the boiler control process (S200). In the boiler control process, the processor 101 first acquires load information from the steam utilization facility 9 and stores it in the load history storage unit 103a (S201). The acquired load information may be stored each time the boiler control process is executed, or each time the boiler control process is executed a predetermined number of times. In addition, the load history storage unit 103a may store date and time information linked to the load information. Furthermore, the load history storage unit 103a may store only the load information for the most recent week, or may accumulate load information for the past several years, for example. As described above, the processor 101 executes the process of S201 as the load information acquisition unit 101a.

Next, the processor 101 acquires the steam header pressure from the pressure sensor 10 (S202). The processor 101 then determines the combustion position based on the load information stored in the load history storage unit 103a, the acquired steam header pressure, and the combustion pattern stored in the combustion pattern storage unit 103c (S203).

Here, for example, if the load on the steam utilization equipment 9 is on an upward trend and exceeds a threshold, the boiler combustion position is changed to the high load side based on the combustion pattern. Also, for example, if the load on the steam utilization equipment 9 is on a downward trend and falls below a threshold, the boiler combustion position is changed to the low load side based on the combustion pattern. When it is decided to change the combustion position, the processor 101 updates the combustion position in the combustion position memory unit 103d.

Next, the processor 101 outputs a control signal indicating the combustion position of each boiler determined in S203 to the boiler control device (S204). The boiler control device controls the rotation speed of the feedwater pump P and the opening degree of the flow control valve V based on the received control signal. As described above, the processor 101 executes the boiler control process as the boiler control unit 101d.

As described above, the boiler control system S includes a boiler group including a plurality of boilers (first boiler 1, second boiler 2, third boiler 3, fourth boiler 4), and a control device (unit number control device 100, first boiler control device 1A, second boiler control device 2A, third boiler control device 3A, fourth boiler control device 4A) that stores a plurality of combustion patterns that define the operating load of each of the plurality of boilers for each total load of the boiler group and controls the operating load of the boilers based on the combustion patterns. The control device then derives the average load of the boiler group for a predetermined period, determines one of the plurality of combustion patterns based on the derived average load, and determines the operating load of each of the plurality of boilers based on the determined combustion pattern and the total load.

Here, the multiple combustion patterns differ from one another in the number of boilers in operation that is specified for at least some of the total loads. As an example, as shown in the upper diagrams of Figures 3 to 6, the number of boilers in operation that is specified for a total load of around 1.2 t/h is four for the normal combustion pattern, three for the three-unit standard combustion pattern, two for the two-unit standard combustion pattern, and one for the one-unit standard combustion pattern. In this way, even if the total load of the boiler group is the same, the number of boilers in operation differs depending on the selected combustion pattern, thereby improving boiler efficiency.

Although the preferred embodiment of the present invention has been described above with reference to the attached drawings, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

For example, the above combustion patterns are merely examples. The relationship between the total load defined in the combustion pattern and the combustion position of each boiler can be set as appropriate. Also, in the above, the combustion patterns are classified into four types, ranging from the one-unit standard combustion pattern, which has one basic boiler in operation, to the normal combustion pattern, which assumes that all boilers are in operation. However, for example, the combustion patterns may be classified into one of three types: the normal combustion pattern, the three-unit standard combustion pattern, and the two-unit standard combustion pattern.

In the above, the multiple combustion patterns are linked to the boiler's feedwater temperature, and the unit count control device 100 determines the combustion pattern based on the average load and the feedwater temperature. However, the combustion pattern may be determined based only on the average load, regardless of the feedwater temperature.

In the above, the first boiler control device 1A, the second boiler control device 2A, the third boiler control device 3A, the fourth boiler control device 4A, and the number control device 100 are described as the control devices. However, the configuration of the control devices and the division of control roles are merely examples. For example, in the above, the number control device 100, which is the higher-level control device, determines the combustion pattern and combustion position, and the boiler control devices (the first boiler control device 1A, the second boiler control device 2A, the third boiler control device 3A, and the fourth boiler control device 4A), which are the lower-level control devices, control the feedwater pump P and the flow control valve V as boiler operation control.

In contrast, for example, a unit count control device 100 may be provided as the control device, and the unit count control device 100 may be responsible for determining the combustion pattern, the combustion position, and all of the operation control of each boiler.

Also, for example, the number control device 100 may determine the combustion pattern, and the boiler control device may determine the combustion position and control the operation of the boiler. In this case, the pressure sensor 10
The steam header pressure detected by the above is input to the boiler control device. The boiler control device may then control the combustion position of each boiler based on the combustion pattern and the steam header pressure received from the unit count control device 100.

The period for calculating the average load is not particularly limited. For example, the average load for each day may be calculated, and the combustion pattern for the next day may be determined based on the calculated average load. Alternatively, the average load for each day of the week may be calculated, and the combustion pattern for the current day may be determined based on the average load for the same day of the previous week.

The unit count control device 100 may also derive the average load for each day and store the average load for each day of the week. Then, by comparing the average load for each day of the week, if a unique day of the week is identified, the combustion pattern may be made different only for that day. For example, if the average load every Wednesday is significantly different from the average load for other days of the week, the combustion pattern for Wednesday may be made different from the combustion patterns for the other days of the week. In this case, the average load for Wednesday may be included or excluded from the average load derived when determining the combustion pattern for days other than Wednesday.

Also, instead of or in addition to the above-mentioned peculiar days of the week, peculiar time periods may be set. In other words, based on the load history, a time period in which the load per unit time is significantly different from other time periods is identified as a peculiar time period. A combustion pattern different from other time periods may be determined for the peculiar time period. In this case, for example, even if the load fluctuation is large, if the time period is extremely short, it may be determined to be an abnormal value rather than a peculiar time period. If it is determined to be an abnormal value, the corresponding time period is not identified as a peculiar time period or date and time.

Reference Signs List 1 First boiler 1A First boiler control device 2 Second boiler 2A Second boiler control device 3 Third boiler 3A Third boiler control device 4 Fourth boiler 4A Fourth boiler control device 100 Number control device 101 Processor 101b Average load derivation unit 101c Combustion pattern determination unit 101d Boiler control unit 102 Memory S Boiler control system

Claims (2)

A boiler group including a plurality of boilers;
a control device that stores a plurality of combustion patterns that define an operating load of each of the plurality of boilers for each total load of the boiler group, and controls the operating load of the boilers based on the combustion patterns;
Equipped with
The plurality of combustion patterns are different from each other in the number of operating boilers defined in at least a part of the total loads,
The control device includes:
Deriving an average load of the boiler group for a predetermined period including a plurality of sections ;
determining one of the plurality of combustion patterns based on the derived average load, and when the average load of one section included in a predetermined period differs from the average load of another section included in the predetermined period by a predetermined value or more, making the combustion pattern of the one section different from the combustion pattern of the other section;
determining an operating load for each of the plurality of boilers for a next predetermined period based on the determined combustion pattern and the total load;
Boiler control system. The plurality of combustion patterns are associated with a feedwater temperature of the boiler,
The control device includes:
determining the combustion pattern based on the average load and the feedwater temperature;
The boiler control system of claim 1 .

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