Boiler control system and boiler control method

Abstract

Keep the steam header pressure value within the specified pressure regulation range. [Solution] A boiler control system 1 includes a plurality of boiler units A1, B1 to B6, A2, and A3, a steam header 40, a header pressure sensor 60, and a number control device 30. In the first independent operation control, it is determined whether or not the steam pressure value is equal to or less than a predetermined first threshold, and if it is equal to or less than the first threshold, the corresponding boiler 10 is started to operate in combustion. In the linked operation control, it is determined whether or not the steam pressure value is equal to or less than a predetermined second threshold smaller than the first threshold, and if it is equal to or less than the second threshold, a combustion command is output based on the combustion amount of the boiler of the second boiler unit B1 to B6, and the operation control device 20 that receives the combustion command starts the combustion operation of the corresponding boiler 10. The first independent operation control and the linked operation control are executed in parallel.

Description

[Technical field]

[0001] One aspect of the present invention relates to a boiler control system and a boiler control method. [Background technology]

[0002] Patent Document 1 discloses a multi-boiler installation system that includes multiple boilers, an operation control device provided for each boiler, a steam header that collects steam, a pressure sensor for the steam header, and a number control device that controls the number of boilers based on the pressure value detected by the pressure sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-101095 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, in the above-described number-of-units control, various processes may take time. When the processes take time, it becomes difficult to appropriately follow the steam load fluctuation, and there is a risk that the pressure value of the steam header cannot be kept within a predetermined pressure adjustment range.

[0005] One aspect of the present invention has been made in consideration of the above-described circumstances, and relates to a boiler control system and a boiler control method that can keep the pressure value of a steam header within a predetermined pressure adjustment range. [Means for solving the problem]

[0006] A boiler control system according to one aspect of the present invention includes a plurality of boiler units, each of which has a boiler, a boiler pressure sensor that detects a steam pressure value corresponding to the boiler, and an operation control device that controls the operation of the boiler, a steam header that collects steam from the boilers of each boiler unit, a header pressure sensor that detects a steam pressure value in the steam header, and a number control device that adjusts the number of boilers that are fired based on the steam pressure value detected by the header pressure sensor, and the plurality of boiler units are divided at least into one or more first boiler units that perform independent operation and a plurality of second boiler units that perform linked operation, and a first independent operation control, which is a control related to the first boiler unit, includes: The operation control device of the boiler unit determines whether the steam pressure value detected by the boiler pressure sensor is below a predetermined first threshold, and if it is below the first threshold, starts combustion operation of the corresponding boiler.In the linked operation control, which is control for the second boiler unit, the number control device determines whether the steam pressure value detected by the header pressure sensor is below a predetermined second threshold which is smaller than the first threshold, and if it is below the second threshold, outputs a combustion command to the operation control device corresponding to the boiler to be burned based on the combustion amount of the boiler of the second boiler unit, and the operation control device that receives the combustion command starts combustion operation of the corresponding boiler.The first independent operation control and the linked operation control are executed in parallel.

[0007] In a boiler control system according to an embodiment of the present invention, a linked operation by a plurality of second boiler units according to a steam pressure value detected by a header pressure sensor and an independent operation by one or a plurality of first boiler units according to a steam pressure value detected by a boiler pressure sensor are performed in parallel. A first threshold value of the steam pressure value that triggers the start of combustion operation in the independent operation is set to a value greater than a second threshold value of the steam pressure value that triggers the output of a combustion command in the linked operation. For this reason, an independent operation is started first, and then the linked operation is started when the steam pressure value further drops. The linked operation requires various processes for increasing or decreasing the number of operating units and transmission of a combustion command value from the unit number control device to the operation control device of each boiler, so that it takes time to generate and stop steam, which is a problem. In this regard, by configuring the system so that an independent operation is performed first, and then the linked operation is performed in parallel when the steam pressure value further drops, the occurrence of delays in generating and stopping steam can be suppressed by the independently operating boiler. This can improve the ability to follow steam load fluctuations, and the pressure value of the steam header can be appropriately kept within a predetermined pressure adjustment range.

[0008] The plurality of boiler units are divided into one or a plurality of first boiler units, a plurality of second boiler units, and one or a plurality of third boiler units that perform independent operation, and in the second independent operation control that is the control related to the third boiler unit, the operation control device of the third boiler unit may determine whether or not the steam pressure value detected by the boiler pressure sensor is equal to or lower than a predetermined third threshold value that is smaller than the second threshold value, and may start the combustion operation of the corresponding boiler if the steam pressure value is equal to or lower than the third threshold value. In this way, the third boiler unit performs independent operation when the steam pressure value falls to or lower than the third threshold value that is smaller than the second threshold value, so that, for example, when there is a sudden (large) steam load fluctuation, independent operation that can be operated without time delay is performed, and it is possible to prevent the pressure value of the steam header from decreasing even during a large steam load fluctuation, and to keep the pressure value of the steam header within a predetermined pressure adjustment range.

[0009] The plurality of boiler units may be arranged in rotation among the first boiler unit, the second boiler unit, and the third boiler unit. In this way, by arranging each boiler unit in rotation among the first boiler unit which has the most opportunities to perform combustion operation, the second boiler unit which has the second most opportunities, and the third boiler unit which has the least opportunities to perform combustion operation, it is possible to prevent deterioration or the like due to heavy operation of only some of the boiler units.

[0010] A boiler control method according to one embodiment of the present invention is a boiler control method executed by a boiler control system, and includes determining whether a steam pressure value in one or more first boiler units operating independently is equal to or less than a predetermined first threshold, and if equal to or less than the first threshold, starting combustion operation of the boiler included in the first boiler unit; determining whether a steam pressure value in a steam header that collects steam is equal to or less than a predetermined second threshold that is smaller than the first threshold, and if equal to or less than the second threshold, adjusting the number of combustion boilers in multiple second boiler units operating in conjunction with each other, and starting combustion operation of the boiler to be combusted. Effect of the Invention

[0011] According to one aspect of the present invention, the pressure value of the steam header can be kept within a predetermined pressure regulation range. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a boiler control system according to this embodiment. [Diagram 2] FIG. 2 is a diagram for explaining the operation of each boiler unit. [Diagram 3] FIG. 3 is a diagram for explaining the operation of each boiler. [Figure 4] FIG. 4 is a flowchart showing the processing of the boiler control system. [Diagram 5] FIG. 5 is a graph illustrating the effect of the boiler control system according to this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0014] FIG. 1 is a diagram showing a schematic configuration of a boiler control system 1 according to the present embodiment. The boiler control system 1 includes a plurality of boiler units A1, B1 to B6, A2, and A3, a unit count control device 30, a steam header 40, a steam pipe 50, and a header pressure sensor 60. The plurality of boiler units A1, B1 to B6, A2, and A3 have the same configuration, but are divided into a first boiler unit A1 that performs independent operation, a plurality (six) of second boiler units B1 to B6 that perform interlocking operation, and a plurality (two) of third boiler units A2 and A3 that perform independent operation according to their roles. As described above, all of the boiler units have the same configuration, so they are arranged in a rotational manner in the first boiler unit, the second boiler unit, and the third boiler unit. For example, the boiler unit described as the first boiler unit A1 in FIG. 1 may rotate to the second boiler units B1 to B6, or may rotate to the third boiler units A2 and A3. Such rotation may be performed daily, or may be performed, for example, once every few weeks or months. Note that in this embodiment, the above-mentioned three types of boiler units are described as being provided, but, for example, only the first boiler unit and the second boiler unit may be provided, and the third boiler unit may not be provided. In addition, the number of boiler units that perform independent operation is not limited to the above, and may be, for example, two first boiler units and one third boiler unit.

[0015] Each of the boilers 10 in the multiple boiler units A1, B1-B6, A2, and A3 is connected to a steam header 40 via a steam pipe 50. The steam header 40 collects steam from the boilers 10 in each boiler unit and supplies the steam to a location (not shown) where the steam is used. A header pressure sensor 60 detects a steam pressure value in the steam header 40. The number-of-boilers control device 30 adjusts the number of combustion boilers in each of the multiple boiler units B1-B6 that operate in conjunction with each other based on the steam pressure value detected by the header pressure sensor 60 (details will be described later).

[0016] The boiler units A1, B1 to B6, A2, and A3 have the same configuration, and each includes a boiler 10, an operation control device 20, and a boiler pressure sensor 70. The boiler 10 may be, for example, a water tube boiler, or more specifically, a once-through boiler. The boiler pressure sensor 70 detects a steam pressure value in the corresponding boiler 10. The boiler pressure sensor 70 outputs the detected steam pressure value to the operation control device 20.

[0017] The operation control device 20 controls the operation of the corresponding boiler 10. The operation control of the boiler 10 by the operation control device 20 is different for a first independent operation control for the first boiler unit A1 performing an independent operation, an interlocking operation control for the second boiler units B1 to B6 performing an interlocking operation, and a second independent operation control for the third boiler units A2 and A3 performing an independent operation. Details of each operation control are described below. The first independent operation control and the second independent operation control are controlled by the operation control device 20, and the interlocking operation control is controlled by the number-of-units control device 30 and the operation control device 20.

[0018] (First independent operation control) The first independent operation control is executed by the operation control device 20 of the first boiler unit A1. The operation control device 20 of the first boiler unit A1 judges whether or not the steam pressure value detected by the boiler pressure sensor 70 of the first boiler unit A1 is equal to or less than a predetermined first threshold value, and when the steam pressure value is equal to or less than the first threshold value, starts the combustion operation of the boiler 10 of the first boiler unit A1. The boiler 10 of the first boiler unit A1 may be in standby in a minimum combustion mode with only a pilot flame before starting the combustion operation. The first threshold value is a value larger than a second threshold value related to the linked operation described later and a third threshold value related to the second independent operation, and may be set to about 0.990 MPa as an example. The value of the first threshold value is merely an example, and may be appropriately set according to various conditions. As described above, since the first threshold value is larger than the second threshold value and the third threshold value, the first independent operation control is executed prior to other controls when the steam pressure value decreases. That is, the boiler 10 of the first boiler unit A1 starts the combustion operation first.

[0019] (Interlocking operation control) The linked operation control is executed by the number of units control device 30 and the operation control device 20 of the second boiler units B1 to B6. The linked operation control is executed simultaneously (in parallel) with the first independent operation control and the second independent operation control. The number of units control device 30 judges whether the steam pressure value detected by the header pressure sensor 60 is equal to or lower than a predetermined second threshold value that is lower than the first threshold value, and when it is equal to or lower than the second threshold value, outputs a combustion command to the operation control device 20 corresponding to the boiler 10 to be burned based on the combustion amount of each boiler 10 of the second boiler units B1 to B6. The combustion command value may be a value indicating 0 to 100%, for example, with the maximum value of the combustion amount being 100%. The second threshold value is a value smaller than the first threshold value and larger than a third threshold value described later, and may be about 0.980 MPa as an example. The value of the second threshold value is merely an example, and may be appropriately set according to various conditions.

[0020] When the steam pressure value detected by the header pressure sensor 60 is equal to or lower than the second threshold value, the number of units control device 30 first outputs a combustion command to the operation control device 20 corresponding to one of the second boiler units B1. Then, the number of units control device 30 adjusts the number of combustion units of the boilers 10 based on the combustion amount of each of the boilers 10 of the second boiler units B1 to B6. After outputting a combustion command to the operation control device 20 corresponding to the second boiler unit B1, the number of units control device 30 determines whether the combustion amount of the boiler 10 in the linked operation (here, the boiler 10 of the second boiler unit B1) is equal to or higher than a predetermined ratio (e.g., 50% or more) of the maximum value, and outputs a combustion command to the operation control device 20 corresponding to the second second boiler unit B2 if the combustion amount is equal to or higher than the predetermined ratio.

[0021] More specifically, when the combustion amount of the boiler 10 (here, the boiler 10 of the second boiler unit B1) in the linked operation is equal to or greater than a predetermined percentage of the maximum value (e.g., 50% or more), a combustion command is output to the operation control device 20 corresponding to the second boiler unit B2 after the additional boiler timer count-up process and the operation preparation process are performed. The additional boiler timer count-up process is a process performed to prevent the number of units from being increased too much when the combustion amount has only increased temporarily, and is a process that counts a predetermined number of seconds (e.g., 30 seconds) and determines whether the combustion amount is equal to or greater than a predetermined percentage of the maximum value even after the count. The operation preparation process is performed only when it is determined in the additional boiler timer count-up process that the combustion amount is equal to or greater than the predetermined percentage of the maximum value even after the count.

[0022] The operation preparation process is a process performed by the boiler 10 (here, the boiler 10 of the second boiler unit B2) that starts operation in response to an instruction from the number control device 30. In the operation preparation process, for example, after pre-purge, pilot burner ignition, main burner ignition, and pressure increase at low combustion are performed, it is confirmed that the detection value of the boiler pressure sensor 70 is equal to or higher than a predetermined value (e.g., 0.590 MPa). Such operation preparation process takes, for example, about 3 minutes. After the operation preparation process is performed, a combustion command is output to the operation control device 20 corresponding to the second boiler unit B2.

[0023] Then, after outputting a combustion command to the operation control device 20 corresponding to the second boiler unit B2, the number control device 30 judges whether the combustion amount of the boiler 10 in the linked operation (here, the boiler 10 of the second boiler units B1 and B2) is equal to or greater than a predetermined percentage (e.g., 50% or more) of the maximum value, and outputs a combustion command to the operation control device 20 corresponding to the third second boiler unit B3 if the combustion amount is equal to or greater than the predetermined percentage. More specifically, when the combustion amount of the boiler 10 in the linked operation (here, the boiler 10 of the second boiler units B1 and B2) is equal to or greater than a predetermined percentage (e.g., 50% or more) of the maximum value, a combustion command is output to the operation control device 20 corresponding to the second boiler unit B3 after an additional boiler timer count-up process and an operation preparation process are performed.

[0024] On the other hand, when the total (or average) value of the combustion amount of the two boilers 10 in the linked operation is, for example, 10% or less of the maximum value, the number control device 30 outputs a first standby command (complete standby command) to the operation control device 20 corresponding to the second second boiler unit B2. More specifically, when the combustion amount of the boilers 10 in the linked operation is, for example, 10% or less of the maximum value, the first standby command is output to the operation control device 20 corresponding to the second second boiler unit B2 after the can reduction timer count-up process is performed. The can reduction timer count-up process is a process performed to prevent the number of boilers from being reduced too much when the combustion amount has only temporarily decreased, and is a process that counts a predetermined number of seconds (for example, 30 seconds) and determines whether the combustion amount is a predetermined percentage or less of the maximum value even after the count. Only when it is determined in the can reduction timer count-up process that the combustion amount is a predetermined percentage or less of the maximum value even after the count, the first standby command is output to the operation control device 20 corresponding to the second second boiler unit B2.

[0025] Furthermore, the number control device 30 further determines whether the steam pressure value detected by the header pressure sensor 60 is greater than or equal to a second threshold value, and if it is greater than or equal to the second threshold value, outputs a second standby command (minimum standby command) to the operation control device 20 corresponding to the second boiler unit B1.

[0026] After outputting a combustion command to the operation control device 20 corresponding to the second boiler unit B3, the number control device 30 judges whether the total (or average) value of the combustion amount of the three boilers 10 (here, the boilers 10 of the second boiler units B1, B2, and B3) in the linked operation is equal to or greater than a predetermined percentage (e.g., 50% or more) of the maximum value, and outputs a combustion command to the operation control device 20 corresponding to the fourth boiler unit B4 if the total (or average) value of the combustion amount of the three boilers 10 in the linked operation (here, the boilers 10 of the second boiler units B1, B2, and B3) is equal to or greater than a predetermined percentage (e.g., 50% or more) of the maximum value. More specifically, when the combustion amount of the boilers 10 in the linked operation (here, the boilers 10 of the second boiler units B1, B2, and B3) is equal to or greater than a predetermined percentage (e.g., 50% or more) of the maximum value, a combustion command is output to the operation control device 20 corresponding to the second boiler unit B4 after the additional boiler timer count-up process and the operation preparation process are performed.

[0027] On the other hand, when the total (or average) value of the combustion amounts of the three boilers 10 in the linked operation is, for example, 10% or less of the maximum value, the number control device 30 outputs a first standby command to the operation control device 20 corresponding to the third second boiler unit B3. More specifically, when the combustion amount of the boiler 10 in the linked operation is, for example, 10% or less of the maximum value, the first standby command is output to the operation control device 20 corresponding to the third second boiler unit B3 after the can reduction timer count-up process is performed. In this case, the number control device 30 performs again the process of determining whether the total (or average) value of the combustion amounts of the two boilers 10 in the linked operation (here, the boilers 10 of the second boiler units B1 and B2) is equal to or greater than a predetermined percentage (for example, 50% or more) of the maximum value.

[0028] After outputting a combustion command to the operation control device 20 corresponding to the second boiler unit B4, the number control device 30 judges whether the total (or average) value of the combustion amount of the four boilers 10 (here, the boilers 10 of the second boiler units B1, B2, B3, and B4) in the linked operation is equal to or greater than a predetermined percentage (e.g., 50% or more) of the maximum value, and outputs a combustion command to the operation control device 20 corresponding to the fifth second boiler unit B5 if the total (or average) value of the combustion amount of the four boilers 10 (here, the boilers 10 of the second boiler units B1, B2, B3, and B4) in the linked operation is equal to or greater than a predetermined percentage (e.g., 50% or more) of the maximum value, after the additional boiler timer count-up process and the operation preparation process are performed, a combustion command is output to the operation control device 20 corresponding to the second boiler unit B5.

[0029] On the other hand, when the total value (or average value) of the combustion amounts of the four boilers 10 in the linked operation is, for example, 10% or less of the maximum value, the number control device 30 outputs a first standby command to the operation control device 20 corresponding to the fourth second boiler unit B4. More specifically, when the total value (or average value) of the combustion amounts of the four boilers 10 in the linked operation is, for example, 10% or less of the maximum value, the first standby command is output to the operation control device 20 corresponding to the fourth second boiler unit B4 after the can reduction timer count-up process is performed. In this case, the number control device 30 performs again the process of determining whether the total value (or average value) of the combustion amounts of the three boilers 10 in the linked operation (here, the boilers 10 of the second boiler units B1, B2, and B3) is equal to or greater than a predetermined percentage (for example, 50% or more) of the maximum value.

[0030] After outputting a combustion command to the operation control device 20 corresponding to the second boiler unit B5, the number control device 30 judges whether the total (or average) value of the combustion amount of the five boilers 10 (here, the boilers 10 of the second boiler units B1, B2, B3, B4, and B5) in the linked operation is equal to or greater than a predetermined percentage (e.g., 50% or more) of the maximum value, and outputs a combustion command to the operation control device 20 corresponding to the sixth boiler unit B5 if the total (or average) value of the combustion amount of the five boilers 10 in the linked operation (here, the boilers 10 of the second boiler units B1, B2, B3, B4, and B5) is equal to or greater than a predetermined percentage (e.g., 50% or more) of the maximum value. More specifically, when the combustion amount of the boilers 10 in the linked operation (here, the boilers 10 of the second boiler units B1, B2, B3, B4, and B5) is equal to or greater than a predetermined percentage (e.g., 50% or more) of the maximum value, a combustion command is output to the operation control device 20 corresponding to the second boiler unit B6 after the additional boiler timer count-up process and the operation preparation process are performed.

[0031] On the other hand, when the total (or average) value of the combustion amounts of the five boilers 10 in the linked operation is, for example, 10% or less of the maximum value, the number control device 30 outputs a first standby command to the operation control device 20 corresponding to the fifth second boiler unit B5. More specifically, when the combustion amount of the boiler 10 in the linked operation is, for example, 10% or less of the maximum value, the first standby command is output to the operation control device 20 corresponding to the fifth second boiler unit B5 after the can reduction timer count-up process is performed. In this case, the number control device 30 performs again the process of determining whether the combustion amount of the boiler 10 in the linked operation (here, the boilers 10 of the second boiler units B1, B2, B3, and B4) is equal to or greater than a predetermined percentage (for example, equal to or greater than 50%) of the maximum value.

[0032] After outputting a combustion command to the operation control device 20 corresponding to the second boiler unit B6, the number control device 30 continues to output combustion commands to the operation control devices 20 of all of the second boiler units B1 to B6 until the total (or average) value of the combustion amounts of the six boilers 10 operating in tandem (here, the boilers 10 of the second boiler units B1, B2, B3, B4, B5, and B6) becomes, for example, 10% or less of the maximum value.

[0033] On the other hand, when the total (or average) value of the combustion amount of the six boilers 10 (here, the boilers 10 of the second boiler units B1, B2, B3, B4, B5, and B6) in the linked operation is, for example, 10% or less of the maximum value, the number control device 30 outputs a first standby command to the operation control device 20 corresponding to the sixth second boiler unit B6. More specifically, when the combustion amount of the boilers 10 in the linked operation is, for example, 10% or less of the maximum value, the first standby command is output to the operation control device 20 corresponding to the sixth second boiler unit B6 after the can reduction timer count-up process is performed. In this case, the number control device 30 performs again the process of determining whether the combustion amount of the boilers 10 in the linked operation (here, the boilers 10 of the second boiler units B1, B2, B3, B4, and B5) is equal to or greater than a predetermined percentage (for example, 50% or more) of the maximum value. In this way, the number of units control device 30 adjusts the number of combustion units of the boiler 10 based on the combustion amount of the second boiler units B1 to B6. Note that the number of units control device 30 may determine the number of combustion units performing combustion operation based on the steam pressure value detected by the header pressure sensor 60.

[0034] The operation control device 20 that has received the combustion command starts the combustion operation of the corresponding boiler 10. Also, the operation control device 20 that has received the standby command stops the combustion operation of the corresponding boiler 10. The operation control device 20 of the second boiler unit B1 (the boiler unit that operates first in interlocking) that has received the second standby command may put the boiler 10 on standby in the minimum combustion mode with only a pilot fire. The operation control device 20 of the second boiler units B2 to B6 (boiler units other than the boiler unit that operates first in interlocking) that have received the first standby command may put the boiler 10 on standby in a complete standby state without even a pilot fire. The second boiler unit B1 that starts the combustion operation first may always be arranged in rotation.

[0035] (Second independent operation control) The second independent operation control is executed by the operation control device 20 of the third boiler units A2 and A3, which are two units. The operation control device 20 of the third boiler unit A2 judges whether the steam pressure value detected by the boiler pressure sensor 70 of the third boiler unit A2 is equal to or lower than a predetermined third threshold value that is smaller than the second threshold value, and starts the combustion operation of the boiler 10 of the third boiler unit A2 when the steam pressure value is equal to or lower than the third threshold value. Similarly, the operation control device 20 of the third boiler unit A3 judges whether the steam pressure value detected by the boiler pressure sensor 70 of the third boiler unit A3 is equal to or lower than a predetermined third threshold value that is smaller than the second threshold value, and starts the combustion operation of the boiler 10 of the third boiler unit A3 when the steam pressure value is equal to or lower than the third threshold value. The third threshold value is a value smaller than the first threshold value related to the first independent operation and the second threshold value related to the linked operation, and may be set to about 0.960 Mpa, for example. The value of the third threshold value is merely an example, and may be set appropriately according to various conditions.

[0036] Such processing of the two third boiler units A2 and A3 may be performed in series. That is, for example, the control by the operation control device 20 of the third boiler unit A2 may be performed first, and then the control by the operation control device 20 of the third boiler unit A3 may be performed. In this case, for example, first, it is determined whether the steam pressure value detected by the boiler pressure sensor 70 of the third boiler unit A2 is equal to or less than the third threshold, and if it is equal to or less than the third threshold, the combustion operation of the boiler 10 of the third boiler unit A2 is started. Then, for example, after a predetermined period of time has elapsed, it is determined whether the steam pressure value detected by the boiler pressure sensor 70 of the third boiler unit A3 is equal to or less than the third threshold, and if it is equal to or less than the third threshold, the combustion operation of the boiler 10 of the third boiler unit A3 is started. Then, after a predetermined period of time has elapsed, it is determined whether the steam pressure value detected by the boiler pressure sensor 70 of the third boiler unit A3 is equal to or less than the third threshold, and if it is equal to or less than the third threshold, the boiler 10 of the third boiler unit A3 is stopped. Furthermore, after a predetermined period of time has elapsed, it is determined whether the steam pressure value detected by the boiler pressure sensor 70 of the third boiler unit A2 is equal to or greater than a third threshold, and if it is equal to or greater than the third threshold, the boiler 10 of the third boiler unit A2 is stopped. The operation control device 20 of the third boiler units A2 and A3 may put the boiler 10 on standby in a minimum combustion mode with only a pilot fire.

[0037] FIG. 2 is a diagram for explaining the operation of each of the above-mentioned boiler units (first boiler unit A1, second boiler units B1 to B6, and third boiler units A2 and A3). Assume that 0.990 Mpa is set as the first threshold value for the first boiler unit A1, 0.980 Mpa as the second threshold value for the second boiler units B1 to B6, and 0.960 Mpa as the third threshold value for the third boiler units A2 and A3. When the steam pressure value drops to the first threshold value (0.990 Mpa) or less, combustion is started in the boiler 10 of the first boiler unit A1 that is operating independently. Note that until combustion is started, the boiler 10 of the first boiler unit A1 is in the minimum combustion mode with only a pilot flame. When the steam pressure value further drops to the second threshold value (0.980 Mpa) or less, combustion is started in the second boiler units B1 to B6 that are operating in conjunction with each other. When the steam pressure value further decreases to a third threshold value (0.960 MPa) or less, combustion is started in the third boiler units A2 and A3, which are operating independently. Note that until combustion is started, the boilers 10 of the third boiler units A2 and A3 are in the minimum combustion mode with only pilot fire.

[0038] 3 is a diagram for explaining the detailed operation of each boiler unit. For example, for the second boiler units B1 to B6 that perform interlocking operation, only the boiler 10 of the second boiler unit B1 that starts combustion operation first is set to the lowest combustion mode with only a pilot light, and the boilers 10 of the other second boiler units B2 to B6 are in a completely standby state (a standby state without a pilot light). Then, when the steam pressure value decreases and becomes equal to or lower than the second threshold value (0.980 MPa), first, the combustion operation of the boiler 10 of the second boiler unit B1 is started, and for the boilers 10 of the other second boiler units B2 to B6, combustion is appropriately started based on the combustion amount of the boilers 10 that are burning.

[0039] In addition, as shown by way of example in the columns for the second boiler units B2 and B3 in Figure 3, as described above, the can increase timer count-up process and operation preparation process may be performed when combustion begins, and the can decrease timer count-up process may be performed when standby begins.

[0040] Next, a boiler control method executed by the boiler control system 1 will be described with reference to the flowchart of Fig. 4. Fig. 4 is a flowchart showing the processing of the boiler control system 1. In the explanation using Fig. 4, the explanation of the above-mentioned can increase timer count-up processing, operation preparation processing, and can decrease timer count-up processing will be omitted.

[0041] First, each boiler 10 is put into a standby state (step S1). For example, the boilers 10 of the first boiler unit A1, the second boiler unit B1, and the third boiler units A2 and A3 are on standby in a minimum combustion mode with only a pilot light. The boilers 10 of the second boiler units B2 to B6 are on standby in a completely standby state with no pilot light.

[0042] Next, it is determined whether or not the steam pressure value detected by the boiler pressure sensor 70 of the first boiler unit A1 is equal to or less than the first threshold value TH1 (step S2). While it is determined in step S2 that the steam pressure value is not equal to or less than the first threshold value TH1, the determination in step S2 is periodically repeated at predetermined time intervals.

[0043] On the other hand, if it is determined in step S2 that the steam pressure value is equal to or lower than the first threshold value TH1, the combustion operation of the boiler 10 of the first boiler unit A1 is started (step S3). Thereafter, it is determined whether the steam pressure value has returned to equal to or higher than the first threshold value TH1 (step S4), and if it has returned to equal to or higher than the first threshold value TH1, the boiler 10 of the first boiler unit A1 is put into standby again (step S5).

[0044] If the steam pressure value has not recovered to the first threshold value TH1 or higher in step S4, it is determined whether the steam pressure value detected by the header pressure sensor 60 is equal to or lower than the second threshold value TH2 (step S6). If it is determined in step S6 that the steam pressure value is not equal to or lower than the second threshold value TH2, the process of step S4 is executed again.

[0045] On the other hand, when it is determined in step S6 that the steam pressure value is equal to or lower than the second threshold value TH2, linked operation control is started (step S7). In the linked operation control, the combustion operation of the boiler 10 to be combusted is started based on the combustion amount of the boiler 10 of the second boiler units B1 to B6. Thereafter, it is determined whether the steam pressure value detected by the header pressure sensor 60 has returned to equal to or higher than the second threshold value TH2 (step S8). When the steam pressure value has returned to equal to or higher than the second threshold value TH2, the boilers 10 of the second boiler units B1 to B6 are put into a standby state again (step S9), and the process of step S4 is executed again.

[0046] In parallel with the process of step S6, it is determined whether the steam pressure value detected by the boiler pressure sensor 70 of the third boiler unit A2 is equal to or less than the third threshold value TH3 (step S10). If it is determined in step S10 that the steam pressure value is not equal to or less than the third threshold value TH3, the process of step S4 is executed again.

[0047] On the other hand, when it is determined in step S10 that the steam pressure value is equal to or less than the third threshold value TH3, the second independent operation control is started (step S11). In the second independent operation control, for example, first, it is determined whether or not the steam pressure value detected by the boiler pressure sensor 70 of the third boiler unit A2 is equal to or less than the third threshold value TH3, and if it is equal to or less than the third threshold value TH3, the combustion operation of the boiler 10 of the third boiler unit A2 is started. Then, for example, after a predetermined period of time has elapsed, it is determined whether or not the steam pressure value detected by the boiler pressure sensor 70 of the third boiler unit A3 is equal to or less than the third threshold value TH3, and if it is equal to or less than the third threshold value TH3, the combustion operation of the boiler 10 of the third boiler unit A3 is started. After that, after a predetermined period of time has elapsed, it is determined whether or not the steam pressure value detected by the boiler pressure sensor 70 of the third boiler unit A3 is equal to or more than the third threshold value TH3, and if it is equal to or more than the third threshold value TH3, the boiler 10 of the third boiler unit A3 is put into a standby state. Furthermore, after a predetermined period of time has elapsed, it is determined whether or not the steam pressure value detected by the boiler pressure sensor 70 of the third boiler unit A2 is equal to or greater than the third threshold value TH3 (step S12). If the steam pressure value is not equal to or greater than the third threshold value TH3, the process of step S11 is executed again, and if the steam pressure value is equal to or greater than the third threshold value TH3, the boiler 10 of the third boiler unit A2 is placed in a standby state (step S13), and the process of step S4 is executed again.

[0048] Next, the effects of the boiler control system 1 according to this embodiment will be described.

[0049] The boiler control system 1 according to the present embodiment includes a plurality of boiler units A1, B1 to B6, A2, and A3 each having a boiler 10, a boiler pressure sensor 70 for detecting a steam pressure value corresponding to the boiler 10, and an operation control device 20 for controlling the operation of the boiler 10, a steam header 40 for collecting steam from the boilers 10 of the boiler units A1, B1 to B6, A2, and A3, a header pressure sensor 60 for detecting a steam pressure value in the steam header 40, and a number control device 30 for adjusting the number of boilers 10 to be burned based on the steam pressure value detected by the header pressure sensor 60. The plurality of boiler units A1, B1 to B6, A2, and A3 are at least divided into a first boiler unit A1 that performs an independent operation and a plurality of second boiler units B1 to B6 that perform interlocking operation. In the first independent operation control, which is a control for the first boiler unit A1, the operation control device 20 of the first boiler unit A1 judges whether or not the steam pressure value detected by the boiler pressure sensor 70 is equal to or less than a predetermined first threshold, and starts the combustion operation of the corresponding boiler 10 if it is equal to or less than the first threshold. In the linked operation control, which is a control for the second boiler units B1 to B6, the number control device 30 judges whether or not the steam pressure value detected by the header pressure sensor 60 is equal to or less than a predetermined second threshold smaller than the first threshold, and if it is equal to or less than the second threshold, outputs a combustion command to the operation control device 20 corresponding to the boiler 10 to be burned based on the combustion amount of the boiler of the second boiler units B1 to B6, and the operation control device 20 that receives the combustion command starts the combustion operation of the corresponding boiler 10. The first independent operation control and the linked operation control are executed in parallel.

[0050] In the boiler control system 1 according to the present embodiment, the interlocking operation by the second boiler units B1 to B6 according to the steam pressure value detected by the header pressure sensor 60 and the independent operation by the first boiler unit A1 according to the steam pressure value detected by the boiler pressure sensor 70 are performed in parallel. The first threshold value of the steam pressure value which is a trigger for starting the combustion operation in the independent operation is set to a value larger than the second threshold value of the steam pressure value which is a trigger for outputting a combustion command in the interlocking operation. Therefore, the independent operation is started first, and then the interlocking operation is started when the steam pressure value further decreases. In the interlocking operation, when the number of operating units is increased or decreased, the above-mentioned can increase timer count-up process or can decrease timer count-up process may be performed, each of which takes, for example, about 30 seconds. In addition, when a new combustion is started from a standby state where the pilot light is not lit, the above-mentioned preparation process takes, for example, about 3 minutes. As described above, in the conventional interlocking operation, various processes take time, making it difficult to appropriately follow the steam load fluctuation, and there was a problem that the pressure value of the steam header could not be kept within a predetermined pressure adjustment range. Furthermore, since it is necessary to transmit a combustion command value from the number control device 30 to the operation control device 20 of each boiler 10, a time delay in the various processes described above can be a problem. In this regard, by configuring the system so that an independent operation is performed first, and then when the steam pressure value further drops, the linked operation is performed in parallel, the occurrence of delays in steam generation and stopping can be suppressed by the independently operating boiler. This can improve the ability to follow steam load fluctuations, and the pressure value of the steam header 40 can be appropriately kept within a predetermined pressure adjustment range.

[0051] Fig. 5 is a graph for explaining the effect of the boiler control system according to this embodiment. In Fig. 5, the horizontal axis indicates time, and the vertical axis indicates pressure. The solid line indicates the pressure of the steam header 40 when only the interlocking operation is performed (steam header pressure I), and the two-dot chain line indicates the pressure of the steam header 40 when the above-mentioned first independent operation and interlocking operation are performed in parallel (steam header pressure II). In Fig. 5, the dotted lines indicate the upper and lower limits of the pressure adjustment range of the steam header 40. As shown in Fig. 5, compared to the case of only the interlocking operation (steam header pressure I), when the first independent operation and the interlocking operation are performed in parallel (steam header pressure II), the fluctuation of the pressure value of the steam header 40 can be reduced and can be kept within the pressure adjustment range.

[0052] The plurality of boiler units may be divided into a first boiler unit A1, a plurality of second boiler units B1 to B6, and two third boiler units A2 and A3 that perform independent operation. In the second independent operation control that is the control for the third boiler units A2 and A3, the operation control device 20 of the third boiler units A2 and A3 may determine whether or not the steam pressure value detected by the boiler pressure sensor 70 is equal to or lower than a predetermined third threshold value that is smaller than the second threshold value, and may start the combustion operation of the corresponding boiler 10 when the steam pressure value is equal to or lower than the third threshold value that is smaller than the second threshold value. In this way, the third boiler units A2 and A3 perform independent operation when the steam pressure value falls to or lower than the third threshold value that is smaller than the second threshold value, so that, for example, when there is a sudden (large) steam load fluctuation, independent operation that can be operated without time delay is performed, and the pressure value of the steam header 40 is prevented from decreasing even during a large steam load fluctuation, and the pressure value of the steam header 40 can be kept within a predetermined pressure adjustment range.

[0053] In Fig. 5, the dashed line indicates the pressure of the steam header 40 (steam header pressure III) when the first independent operation, the interlocking operation, and the second independent operation are performed in parallel. As shown in Fig. 5, when the first independent operation, the interlocking operation, and the second independent operation are performed in parallel (steam header pressure III), the fluctuation in the pressure value of the steam header 40 was further reduced compared to when the above-mentioned first independent operation and the interlocking operation are performed in parallel (steam header pressure II).

[0054] The plurality of boiler units may be arranged in rotation among the first boiler unit A1, the second boiler units B1 to B6, and the third boiler units A2 and A3. In this way, by arranging each boiler unit in rotation among the first boiler unit A1, which has the most opportunities to perform combustion operation, the second boiler unit B1, etc., and the third boiler units A2 and A3, which have the least opportunities to perform combustion operation, it is possible to prevent deterioration, etc., caused by excessive operation of only some of the boiler units. [Explanation of symbols]

[0055] 1...boiler control system, 10...boiler, 20...operation control device, 30...number control device, 40...steam header, 60...header pressure sensor, 70...boiler pressure sensor, A1...first boiler unit, B1 to B6...second boiler unit, A2, A3...third boiler unit.

Claims

1. A plurality of boiler units, each of which has a boiler, a boiler pressure sensor that detects a steam pressure value corresponding to the boiler, and an operation control device that controls the operation of the boiler; A steam header that collects steam from the boilers of each boiler unit; a header pressure sensor for detecting a steam pressure value in the steam header; a number control device that adjusts the number of combustion boilers based on the steam pressure value detected by the header pressure sensor, The plurality of boiler units are at least divided into one or more first boiler units that perform independent operation, a plurality of second boiler units that perform interlocking operation, and one or more third boiler units that perform independent operation, In the first isolated operation control which is the control related to the first boiler unit, The operation control device of the first boiler unit determines whether or not a steam pressure value detected by the boiler pressure sensor of the corresponding first boiler unit is equal to or less than a predetermined first threshold value, and starts a combustion operation of the corresponding boiler when the steam pressure value is equal to or less than the first threshold value; In the interlocking operation control which is the control regarding the second boiler unit, the number control device determines whether the steam pressure value detected by the header pressure sensor is equal to or less than a predetermined second threshold value that is smaller than the first threshold value, and when the steam pressure value is equal to or less than the second threshold value, outputs a combustion command to the operation control device corresponding to the boiler to be combusted based on the combustion amount of the boiler of the second boiler unit; The operation control device that has received the combustion command starts the combustion operation of the corresponding boiler, The first isolated operation control and the linked operation control are executed in parallel, In the second independent operation control which is the control related to the third boiler unit, The operation control device of the third boiler unit determines whether the steam pressure value detected by the boiler pressure sensor of the corresponding third boiler unit is equal to or lower than a predetermined third threshold value which is lower than the second threshold value, and if the steam pressure value is equal to or lower than the third threshold value, starts combustion operation of the corresponding boiler.

2. A plurality of boiler units, each of which has a boiler, a boiler pressure sensor that detects a steam pressure value corresponding to the boiler, and an operation control device that controls the operation of the boiler; A steam header that collects steam from the boilers of each boiler unit; a header pressure sensor for detecting a steam pressure value in the steam header; a number control device that adjusts the number of combustion boilers based on the steam pressure value detected by the header pressure sensor, The plurality of boiler units are at least divided into one or more first boiler units that perform independent operation and a plurality of second boiler units that perform interlocking operation, In the first isolated operation control which is the control related to the first boiler unit, The operation control device of the first boiler unit determines whether or not a steam pressure value detected by the boiler pressure sensor of the corresponding first boiler unit is equal to or less than a predetermined first threshold value, and starts a combustion operation of the corresponding boiler when the steam pressure value is equal to or less than the first threshold value; In the interlocking operation control which is the control regarding the second boiler unit, the number control device determines whether the steam pressure value detected by the header pressure sensor is equal to or less than a predetermined second threshold value that is smaller than the first threshold value, and when the steam pressure value is equal to or less than the second threshold value, outputs a combustion command to the operation control device corresponding to the boiler to be combusted based on the combustion amount of the boiler of the second boiler unit; The operation control device that has received the combustion command starts the combustion operation of the corresponding boiler, The first isolated operation control and the linked operation control are executed in parallel, A boiler control system, wherein the plurality of boiler units are arranged in rotation between the first boiler unit and the second boiler unit, respectively.

3. A boiler control method executed by a boiler control system, comprising: determining whether or not a steam pressure value in one or more first boiler units performing independent operation is equal to or less than a predetermined first threshold value, and when the steam pressure value is equal to or less than the first threshold value, starting a combustion operation of a boiler included in the first boiler unit; determining whether or not a steam pressure value in a steam header that collects steam is equal to or lower than a predetermined second threshold value that is smaller than the first threshold value, and if the steam pressure value is equal to or lower than the second threshold value, adjusting the number of combustion boilers in the plurality of second boiler units that perform interlocking operation, and starting the combustion operation of the boiler that is the target of combustion; A boiler control method comprising: determining whether a steam pressure value in one or more third boiler units operating independently is equal to or less than a predetermined third threshold value which is smaller than the second threshold value; and if the steam pressure value is equal to or less than the third threshold value, starting combustion operation of a boiler included in the third boiler unit.

4. A boiler control method executed by a boiler control system having a plurality of boiler units, comprising: The plurality of boiler units are at least divided into one or more first boiler units that perform independent operation and a plurality of second boiler units that perform interlocking operation, determining whether or not a steam pressure value in one or more first boiler units performing independent operation is equal to or less than a predetermined first threshold value, and when the steam pressure value is equal to or less than the first threshold value, starting a combustion operation of a boiler included in the first boiler unit; determining whether or not a steam pressure value in a steam header that collects steam is equal to or lower than a predetermined second threshold value that is smaller than the first threshold value, and if the steam pressure value is equal to or lower than the second threshold value, adjusting the number of combustion boilers in a plurality of second boiler units that perform interlocking operation, and starting the combustion operation of the boiler that is the target of combustion; The boiler control method, wherein the plurality of boiler units are rotated to the first boiler unit and the second boiler unit, respectively.

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