Heating system

Abstract

In a heating system equipped with multiple heat sources, the heating load of each heat source during heating operation is equalized. [Solution] Multiple heat source units BL1 to BL4 are connected to a heating circulation path 50 of the heat transfer medium. Each of the multiple heat source units BL1 to BL4, during heating operation, forms a heating path that heats the heat transfer medium introduced from the input terminal 101 and outputs it from the output terminal 102 at a flow rate that increases or decreases according to the output of the heating pumps CP1 to CP4. When two or more of the multiple heat source units BL1 to BL4 are in heating operation, a heating target value is set according to the average value of the current heating load of those two or more heat source units. Furthermore, for those two or more heat source units, a control command is generated to reduce the output of the heating pump for heat source units whose current heating load is higher than the heating target value, while a control command is generated to increase the output of the heating pump for heat source units whose current heating load is lower than the heating target value.

Description

Technical Field

[0001] The present invention relates to a heating system including a plurality of heat source machines.

Background Art

[0002] In order to increase the heating capacity, a heating system is used in which a plurality of heat source machines (such as boilers) that can be operated simultaneously are connected and operated in parallel. <​​​​​​​​​​​​​​​​​​​​​​​​​​​​The present invention was made to solve these problems, and the object of the present invention is to equalize the heating load among two or more heat source units during heating operation in a heating system equipped with multiple heat source units. [Means for solving the problem]

[0007] In one aspect of the present invention, a heating system is provided. The heating system comprises a plurality of heat sources and a control unit. The plurality of heat sources are connected to a circulation path for a heat medium to pass through heating terminals. Each of the plurality of heat sources includes an input terminal and an output terminal connected to the circulation path, a heating mechanism for raising the temperature of the heat medium being passed through, and a heating pump whose output during operation can be changed and controlled. The heating pump is operated during the heating operation of the heat source to form a heating path in which the heat medium introduced from the input terminal passes through the heating mechanism and is output from the output terminal, with a flow rate that increases or decreases according to the output. The control unit performs heating load equalization control for two or more of the plurality of heat sources that are in heating operation. In heating load equalization control, the control unit sets a heating target value according to the average value of the current heating loads of two or more heat source units during heating operation. It is configured to generate a control command to reduce the output of the heating pump for heat source units whose current heating load is higher than the heating target value, while generating a control command to increase the output of the heating pump for heat source units whose current heating load is lower than the heating target value. [Effects of the Invention]

[0008] According to the present invention, in a heating system equipped with multiple heat sources, the heating load can be equalized among two or more heat sources during heating operation. [Brief explanation of the drawing]

[0009] [Figure 1] This is a conceptual diagram illustrating the first example of a heating system installation. [Figure 2] This is a conceptual diagram illustrating a second example of a heating system installation. [Figure 3]Figures 1 and 2 are schematic diagrams showing example configurations of each boiler. [Figure 4] This is a flowchart illustrating the heating control of the heat transfer medium in each boiler. [Figure 5] Figures 1 and 2 are schematic diagrams illustrating an example of communication connection between multiple boilers. [Figure 6] This is a flowchart illustrating the process of heating load equalization control according to this embodiment. [Figure 7] This flowchart explains the control process of a controller that receives a control command for heating load equalization control. [Figure 8] This is a conceptual diagram illustrating a modified example of the process for generating control commands for a heating pump. [Figure 9] This is a schematic diagram showing other configuration examples for each boiler BL. [Figure 10] Figure 9 is a flowchart illustrating the process of equalizing the heating load by the boiler. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described in detail below with reference to the drawings. In the following description, the same or corresponding parts in the drawings will be denoted by the same reference numerals, and their descriptions will not be repeated in principle.

[0011] <Example of a heating system configuration> First, using Figures 1 and 2, we will explain the effect of differences in the connection configurations between multiple heat source units (boilers) and the circulation piping of the heat transfer medium in a heating system on the load of those multiple heat source units.

[0012] Figure 1 is a conceptual diagram illustrating the first example of a heating system installation. Referring to FIG. 1, the heating system 10 includes a heating circulation path 50 which is a circulation path of a heat medium (for example, warm water) constituted by an outgoing pipe 51 and return pipes 52a and 52b, and a plurality of boilers BL1 to BL4 connected to the heating circulation path 50. In this embodiment, the plurality of four boilers BL1 to BL4 are shown as an example of "a plurality of heat source machines". The number of connected boilers (heat source machines) can be any plurality.

[0013] To the heating circulation path 50, n (n: natural number) heating terminals HT1 to HTn are connected. The heating terminals HT1 to HTn each include pumps HP1 to HPn for introducing the heat medium from the heating circulation path 50 and heating appliances HTM1 to HTMn. For example, the heating terminals HT1 to HTn can be constituted by "floor heating equipment" having warm water pipes arranged under the floor as the heating appliances HTM1 to HTMn.

[0014] Hereinafter, the plurality of boilers BL1 to BL4 are also collectively referred to as boiler BL. Similarly, for each of the heating terminals HT1 to HTn, the pumps HP1 to HPn, and the heating appliances HTM1 to HTMn, when collectively referred to, they shall be referred to as heating terminal HT, pump HP, and heating appliance HTM.

[0015] The operation on and off (stop) of each of the heating terminals HT1 to HTn can be controlled by input to a remote control panel (not shown). When each heating terminal HT is in the on operation state, it operates the pump HP to introduce a part of the heat medium flowing through the outgoing pipe 51. The heating appliance HTM can raise the temperature of the installation location by the heat energy of the introduced heat medium as it passes through.

[0016] The heat medium after heat dissipation in the heating appliance HTM is output to the return pipe 52b. That is, the return pipe 52b is connected to the output side of the heat medium of the heating terminals HT1 to HTn. The return pipe 52a is connected to the return pipe 52b at the connection point 54 and is also connected to the forward pipe 51 at the connection point 55. The connection point 54 is located downstream in the circulation direction of the heat medium from the connection points on the output side of the heating terminals HT1 to HTn with respect to the return pipe 52b.

[0017] Each boiler BL1 has an input end 101 connected to the return pipe 52a and an output end 102 connected to the forward pipe 51. The boilers BL1 to BL4 further each have a heating pump CP1 to CP4.

[0018] When at least any one of the heating terminals HT1 to HTn is in the operating-on state, in at least any one of the plurality of boilers BL1 to BL4, a heating operation of the heat medium is executed. In the boiler BL during the heating operation, the heating pump CP (collectively representing CP1 to CP4) operates to heat the heat medium introduced from the input end 101 (return pipe 52a) and output it to the forward pipe 51 from the output end 102.

[0019] As a result, a high-temperature heat medium heated to the output set temperature Tr is output to the forward pipe 51 from the boiler BL during the heating operation. When the heat medium flows from the forward pipe 51 to the operating-on heating terminal HT, it is output to the return pipe 52b after the temperature drops. As a result, the return pipe 52a connected to the return pipe 52b via the connection point 54 receives the heat medium that has flowed through each operating heating terminal HT and then merged.

[0020] And the boiler BL during the heating operation heats the heat medium introduced from the input end 101 connected to the return pipe 52a to the output set temperature Tr and outputs it to the forward pipe 51 via the output end 102. As a result, a circulation path of the heat medium along the arrow direction in the figure is formed in the heating circulation path 50 including the forward pipe 51 and the return pipes 52a and 52b.

[0021] Furthermore, the number of boilers BL1 to BL4 that are in heating operation can be automatically controlled according to the heating load, which depends on the number of heating terminals HT1 to HTn that are in operation (number of operating units).

[0022] For example, if the hot water temperature from each boiler BL cannot be secured even when each boiler BL is operated at its maximum heating capacity (maximum number) according to a predetermined priority order as described in Patent Document 1, the number of boilers BL being operated for heating can be increased by one at a time. As a result, there are cases where two or more boiler BLs are operating for heating. Hereinafter, when two or more boiler BLs are operating for heating, these two or more boilers will also be referred to as "multiple boilers." Figures 1 and 2 illustrate the operation when all of the multiple boilers BL1 to BL4 are operating for heating.

[0023] In the example shown in Figure 1, the input terminal 101 of each boiler BL is connected to the return pipe 52a, unlike the supply pipe 51 to which the output terminal 102 is connected. Therefore, there is no significant difference in the temperature of the heat transfer medium introduced from the input terminal 101 (input temperature Tin) between boilers BL1 to BL4. Furthermore, in a heating system 10 equipped with multiple boilers BL, the output set temperature Tr is a common value for each boiler BL.

[0024] Therefore, in the construction example (pipe connection configuration) shown in Figure 1, where the input terminal 101 of each boiler BL is connected to the return pipe 52a, it can be understood that there is no significant difference in the required heating load among the four boilers BL1 to BL4.

[0025] Figure 2 is a conceptual diagram illustrating a second example of a heating system installation. The construction example in Figure 2 differs from the construction example in Figure 1 in that the connection destination of the input terminal 101 of each boiler BL is the supply pipe 51, just like the connection destination of the output terminal 102. In all other respects, the configuration of the heating system 10 in Figure 2 is the same as in Figure 1, so a detailed explanation will not be repeated.

[0026] Here, similar to Figure 1, we consider a state where all of the boilers BL1 to BL4 are in heating operation, and the heating terminals HT1 to HTn operate in the same way as in Figure 1.

[0027] In the piping connection configuration shown in Figure 2, boilers BL1 to BL4 have their input terminals 101 and output terminals 102 connected to a common supply pipe 51. Therefore, when boiler BL4, the upstreammost boiler in the heat transfer medium circulation path, heats a portion of the heat transfer medium in the supply pipe 51 and outputs it from its output terminal 102, the next boiler BL3 operates by introducing a portion of the heat transfer medium, including the output from boiler BL4 to the supply pipe 51, from its input terminal 101 and outputting it to the supply pipe 51 from its output terminal 102. Subsequently, moving from the upstream to the downstream side of the heat transfer medium circulation path, the downstream boiler BL further heats the heat transfer medium, including the output (after heating) from the upstream boiler BL to the supply pipe 51, and returns it to the supply pipe 51.

[0028] Therefore, considering a situation where the combined heating capacity of the four boilers BL1 to BL4 supplies a heat transfer medium at the same temperature as shown in Figure 1 to the heating circulation path 50, the input temperature Tin of the heat transfer medium to boilers BL1 to BL4 changes depending on the location of each boiler BL, more specifically, the connection position of the input terminal 101 to the heat transfer medium circulation path (supply pipe 51). As a result, if heating operations to raise the temperature to a common output set temperature Tr are performed similarly in each boiler BL, there is a concern that the heating load will be uneven among boilers BL1 to BL4.

[0029] This raises concerns that the heating system 10 may not be able to operate normally without malfunctions or failures for a longer period, as the upstream boiler BL, which experiences an increased heating load, is more prone to failure.

[0030] Furthermore, it is understood that the above-mentioned problem of uneven heating load is not limited to cases where all four boilers BL1 to BL4 are in heating operation, but can similarly occur even when only two or three boilers are in heating operation, depending on the location of the boilers in heating operation (upstream / downstream of the heat transfer medium circulation path).

[0031] Therefore, in the heating system according to this embodiment, even under the construction example (piping connection configuration) shown in Figure 2, control is performed to equalize the heating load of the heat transfer medium among multiple boilers during heating operation (hereinafter referred to as "heating load equalization control").

[0032] It should be noted that the configuration of the heating circulation path 50, shown in Figures 1 and 2 with the connection of the supply pipe 51 and return pipes 52a and 52b, is merely an example. For example, the return pipes 52a and 52b are shown as separate pipes in Figure 1 for convenience to distinguish their respective connection destinations, and it is also possible to configure them as a single integrated pipe. Alternatively, the supply pipe 51 and the return pipe 52a can also be configured as a single integrated pipe. Furthermore, each of the illustrated supply pipe 51 and return pipes 52a and 52b may be a single pipe, or they may be configured by connecting multiple pipes.

[0033] <Example of boiler (heat source) configuration> Next, we will explain an example of the boiler BL configuration shown in Figures 1 and 2 using Figure 3. Figure 3 shows an example where the boiler BL is a hot water heating-only heat source unit that has a heating function but does not have a hot water supply function.

[0034] As shown in Figure 3, the boiler BL includes an input terminal 101, an output terminal 102, and a heating pump CP, as well as an exhaust pipe 106, a controller 110, a combustion burner 120 and a heat exchanger 130 housed in the boiler body 105, and heat transfer medium piping 201-203.

[0035] The combustion burner 120 receives a supply of fuel, such as gas, and generates heat through the combustion of the fuel. The fuel is supplied to the combustion burner 120 via a flow control valve 121. The flow rate of gas supplied to the combustion burner 120, and thus the amount of heat generated in the combustion burner 120, can be controlled by adjusting the rotation speed of a combustion fan (not shown).

[0036] The heat exchanger 130 includes a primary heat exchanger 131 that primarily heats the fluid using the sensible heat of fuel combustion in the combustion burner 120, and a secondary heat exchanger 132 that primarily heats the fluid using the latent heat of exhaust gas from fuel combustion.

[0037] The combustion exhaust gas produced by the combustion of the combustion burner 120 is discharged to the outside of the boiler BL via the exhaust pipe 106. In addition, the acidic water (condensate) generated in the secondary heat exchanger 132 is collected in the drain tank 195, neutralized, and then discharged to the outside.

[0038] The input terminal 101, into which the heat transfer medium is supplied from the heating circulation path 50 shown in Figures 1 and 2, is connected to the input side of the secondary heat exchanger 132 by piping 201. Piping 202 connects the output side of the secondary heat exchanger 132 to the input side of the primary heat exchanger 131. The output side of the primary heat exchanger 131 is connected to the output terminal 102 by piping 203.

[0039] A heating pump CP is connected to piping 201. The heating pump CP consists of a DC motor or AC motor whose output (typically, rotational speed) can be variably controlled. For example, a heating pump CP whose output (rotational speed) can be changed and controlled can be configured by using a DC motor to which a DC pulse with a variably controlled duty cycle is applied from a chopper (not shown), or an AC motor to which a variable frequency AC voltage is applied from an inverter (not shown).

[0040] During the heating operation of boiler BL, the heating pump CP operates, causing the heat transfer medium introduced from input terminal 101 to pass through piping 201, secondary heat exchanger 132, piping 202, primary heat exchanger 131, and piping 203, and be output from output terminal 102 to the heating circulation path 50 (supply piping 51). The introduced heat transfer medium is heated in the heat exchanger 130 by the heat generated by the combustion burner 120, thereby forming one embodiment of a "heating path" inside boiler BL through the path from input terminal 101 to output terminal 102 described above. The flow rate Q of the heat transfer medium in the heating path can be variably controlled by the output of the heating pump CP.

[0041] A temperature sensor 251 is located in piping 201 to detect the input temperature Tin of the heat transfer medium. A temperature sensor 252 is located in piping 203 to detect the output temperature Tout of the heat transfer medium from the heat exchanger 130. Temperature sensors 251 and 252 are typically composed of thermistors.

[0042] The controller 110 operates by receiving a power supply voltage (for example, DC 15V) from the power supply circuit 117. The power supply circuit 117 converts power from the boiler BL's external power supply (for example, commercial AC power) into a power supply voltage.

[0043] The controller 110 includes a CPU (Central Processing Unit) 111, a memory 112, an interface 115, and a communication unit 116. Output values ​​from various sensors, including temperature sensors 251 and 252, are input to the controller 110 via the interface 115. Control signals from the controller 110 can also be output to each piece of equipment within the boiler BL via the interface 115.

[0044] The controller 110 controls the operation of each component so that the boiler BL operates according to the user's operating commands by executing a program pre-stored in the memory 112. For example, the controller 110 can control the output of the heating pump CP, including stopping it (output = 0), by outputting a control signal (not shown) to the heating pump CP. The controller 110 can also control the amount of heat generated at the combustion burner 120 by outputting a control signal (not shown) to the combustion fan.

[0045] Figure 4 shows a flowchart illustrating the heating control of the heat transfer medium in each boiler BL. The control process shown in Figure 4 is repeatedly executed at regular intervals by the controller 110 of each boiler BL.

[0046] As shown in Figure 4, the controller 110 obtains the input temperature Tin [°C] of the heat transfer medium based on the value detected by the temperature sensor 251 in step (hereinafter simply referred to as "S") 110.

[0047] Furthermore, the controller 110 obtains the flow rate Q [L / min] of the heat transfer medium in the heating path via S120. S110 and S120 may be processed in the reverse order described above, or they may be processed in parallel. In this embodiment, the flow rate Q can be obtained by an estimated value from the output (rotational speed) of the heating pump CP. For example, by creating a characteristic curve in advance that defines the relationship between the flow rate Q and the rotational speed of the heating pump CP, an estimated value of the flow rate Q [L / min] can be obtained from the rotational speed (command value or actual value) of the heating pump CP at the time of execution of S120.

[0048] Alternatively, a flow sensor (not shown) may be placed within the heating path (for example, downstream of the heating pump CP). In this case, the flow rate Q can be obtained in S120 using the detected value of the flow sensor. However, while placing a flow sensor allows for highly accurate acquisition of the flow rate Q, there is a concern that it may increase the piping resistance of the heating path.

[0049] In S130, the controller 110 calculates the heating amount G. The heating amount G can be calculated using the input temperature Tin obtained in S110, the flow rate Q obtained in S120, and the output set temperature Tr* of the heat transfer medium by the following equation (1).

[0050] G = (Tr* - Tin)·Q …(1) Furthermore, the heating amount G may be expressed as a unit of "numbers," where "number 1" is the amount of heating required to raise the temperature of a flow rate of 1 [L / min] by 25 [°C], obtained by dividing the right-hand side of equation (1) by 25.

[0051] Furthermore, each boiler BL has a predetermined maximum heating capacity Gmax (maximum boiler number). Therefore, in S130, if the calculation result from equation (1) exceeds Gmax, a limiting process is performed to replace it with G=Gmax. On the other hand, when G ≤ Gmax, the value calculated from equation (1) can be used directly as the heating amount G.

[0052] The output setting temperature Tr* can be determined for the heating terminal HT when it is turned on, based on the ambient temperature at the installation location and the temperature setting level set by the user (for example, 5 to 10 levels from low to high), using a predetermined calculation formula or the like.

[0053] In S140, the controller 110 calculates the gas flow rate to be supplied to the combustion burner 120 in order to apply the amount of heat G equivalent to that in S130 to the heat transfer medium, taking into consideration the thermal efficiency of the heating mechanism (combustion burner 120 and heat exchanger 130), and generates a fan rotation speed command to produce that gas flow rate as a control command for heating control.

[0054] As a result, heating control is performed in each boiler BL to raise the temperature of the heat transfer medium introduced by the heating pump CP to the output set temperature Tr*. However, if the value calculated in equation (1) exceeds Gmax and is limited to G=Gmax, the output temperature of the heat transfer medium from the boiler BL will be lower than the output set temperature Tr*.

[0055] Referring again to Figure 3, the controller 110 can establish a communication connection with external equipment of the boiler BL via the communication unit 116. For example, communication for sending and receiving data with external equipment becomes possible via the communication cable CBL connected to communication connectors CN1 and CN2.

[0056] Figure 5 is a schematic diagram illustrating an example of communication connections between multiple boilers BL1 to BL4 shown in Figures 1 and 2.

[0057] Figure 5 shows an example of a communication connection in which data can be shared between boilers BL1 to BL4 by connecting two adjacent boilers BL with a communication cable CBL in a so-called daisy-chain configuration.

[0058] Specifically, the communication connector CN2 of boiler BL1 and the communication connector CN1 of boiler BL2 are connected by a communication cable CBL1, enabling bidirectional data communication between the controllers 110 of adjacent boilers BL1 and BL2.

[0059] Similarly, communication cable CBL2 enables bidirectional data communication between the controllers 110 of adjacent boilers BL2 and BL3, and communication cable CBL3 enables bidirectional data communication between the controllers 110 of adjacent boilers BL3 and BL4. In addition, at boilers BL1 and BL4 located at both ends, communication connector CN1 or CN2 (the side without an adjacent boiler BL) is left open, with communication cable CBL not connected. Boilers BL1 and BL4 located at both ends transmit data bidirectionally to the boiler BL adjacent to either the right or left side in the diagram. Thus, it is understood that data from all boilers BL1 to BL4 can be collected.

[0060] <Explanation of Heating Load Equalization Control> In this embodiment, we describe an example in which the controller 110 of one of the boilers BL1, located at the end of a daisy-chain of multiple boilers BL1 to BL4, performs heating load equalization control comprehensively.

[0061] In each boiler BL, the heating control shown in Figure 4 is executed, allowing the amount of heating G(S130) in that boiler BL to be determined as the "current heating load".

[0062] Figure 6 is a flowchart illustrating the heating load equalization control process according to this embodiment. The control process in Figure 6 is executed periodically and repeatedly when two or more boilers (multiple boilers) among the boilers BL1 to BL4 are in heating operation. For example, as described above, the control process in Figure 6 is executed by the controller 110 of boiler BL1, which oversees the heating load equalization control.

[0063] Controller 110 collects the heating amount G(i) as the "current heating load" for each boiler BL using S210. Here, "i" is a variable (natural number) used to distinguish between multiple boiler BLs, and in this example, 1 ≤ i ≤ 4.

[0064] In the example of the communication connection shown in Figure 5, when the heating amount G(i) of each boiler BL1 to BL4 is calculated by the respective controller 110 of boiler BL1 to BL4, the heating amount G(4) of boiler BL4 is transmitted from boiler BL4 to boiler BL3. Next, the heating amounts G(3) and G(4) of boilers BL3 and BL4 are transmitted from boiler BL3 to boiler BL2, and G(2) to G(4) of boilers BL2 to BL4 are transmitted from boiler BL2 to boiler BL1. As a result, the controller 110 of boiler BL1 can collect multiple heating amounts G(1) to G(4) of boilers BL1 to BL4, including the G(1) it calculated.

[0065] In S220, the controller 110 calculates the target heating value G* for multiple boilers during heating operation based on the heating amount G(i) of each boiler BL collected in S210. For example, in S220, the target heating value G* can be calculated using the average value of the heating amount G(i) of each boiler BL acquired in S210, excluding those where G=0.

[0066] In S230, the controller 110 initializes the variable i to 1. Then, in S235, it determines whether G(i) > 0 for the current value of variable i, that is, whether heating operation is in progress.

[0067] When G(i) > 0, that is, when the boiler (BLi) indicated by the variable i is in the heating operation (when the YES determination is made in S235), the process proceeds to S240. In S240, the heating quantity G(i) is compared with the heating target value G* (S220).

[0068] When G(i) < G* (when the YES determination is made in S240), the controller 110, in S260, generates a control command for increasing the heating load for the boiler (BLi), which is a control command for increasing the output of the heating pump CP (increasing the rotational speed) to increase the flow rate of the heat medium in the heating path.

[0069] On the contrary, when G(i) ≥ G* (when the NO determination is made in S240), the controller 110, in S250, generates a control command for increasing the heating load for the boiler (BLi), which is a control command for decreasing the output of the heating pump CP (decreasing the rotational speed) to decrease the flow rate of the heat medium in the heating path.

[0070] On the other hand, for a boiler BL that is not in the heating operation with G(i) = 0, S235 is determined as NO, and the processes of S240 to S260 are skipped. That is, a control command for the heating pump CP for the heating load equalization control is not generated. That is, an increase or decrease in the output of the heating pump CP for the heating load equalization control is not instructed.

[0071] In S270, the controller 110 determines whether the value of the variable i has reached the total number N of the plurality of boilers BL (here, N = 4). When i < N, in S280, after increasing the value of the variable i by 1, the process returns to S235.

[0072] As a result, the processes from S235 to S270 are repeatedly executed until i=N. When the YES determination in S270 is made (i=N), a control command is generated for each of the multiple boiler BLs (Bassers Blue) that are in heating operation among the multiple (N) boilers, through the process in S250 or S260. Furthermore, a control command indicating that no response to heating load equalization control is required can be generated for boilers that are not in heating operation. Then, in S290, the controller 110 adds identification information indicating which boiler BL the control command is for, and transmits the control command to each boiler BL.

[0073] For example, in the communication connection example shown in Figure 5, when the controller 110 of boiler BL1 generates control commands for boilers BL1 to BL4, the control commands for boilers BL2 to BL4 are sent from boiler BL1 to boiler BL2. Next, the control commands for boilers BL3 and BL4 are sent from boiler BL2 to boiler BL3, and the control command for boiler BL4 is sent from boiler BL3 to boiler BL4. As a result, each of the boilers BL1 to BL4 can obtain control commands for heating load equalization control.

[0074] Figure 7 shows a flowchart illustrating the control process of a controller that receives a control command for heating load equalization control. The control process in Figure 7 is executed, for example, by each controller 110 of boilers BL2 to BL4.

[0075] As shown in Figure 7, in S310, the controller 110 transmits the heating amount G(i) of the boiler BL calculated in S130 (Figure 4) (i=2~4). As described above, the heating amounts G(2)~G(4) transmitted from boilers BL2~BL4 are ultimately transmitted to boiler BL1 via the communication connection shown in Figure 5.

[0076] In S320, when the controller 110 receives a control command from boiler BL1 (controller 110) for heating load equalization control of the heating pump CP for the boiler BL, in S330 it generates a control signal to increase or decrease the output (rotational speed) of the heating pump CP.

[0077] As a result, the flow rate of the heat transfer medium in the heating path changes so that the amount of heat G in the boiler BL approaches the target heating value G* (for example, the average value of the current amount of heat in the boiler BL during heating operation). Consequently, regardless of how the multiple heat sources are connected to the heating circulation path 50, even if they are connected as shown in Figure 2 above, the heating load can be equalized among the multiple boiler BLs during heating operation.

[0078] Furthermore, the heating load equalization control according to this embodiment can be implemented regardless of the piping connection configuration of the multiple heat source units to the heating circulation path 50. However, when the piping connection configuration is as shown in Figure 2, a greater effect can be enjoyed compared to the case where this control is not implemented.

[0079] Furthermore, the process of generating control commands for the heating pump CP in steps S240-S260 of Figure 6 can also be performed according to the modified example shown in Figure 8.

[0080] The control commands for the heating pump CP of each boiler BL may be generated in such a way that a dead zone is provided in which the current output (rotational speed) is maintained without increasing or decreasing when the difference between the heating amount G(i) of the boiler BL and the heating target value G* is small.

[0081] For example, as shown in FIG. 8, for a predetermined constant α, a dead zone of G* - α ≤ G(i) ≤ G* + α can be provided. Specifically, when G* - α ≤ G(i) ≤ G* + α, the output of the heating pump CP is maintained, while when G(i) < G* - α, the output of the heating pump CP is increased, and when G(i) > G* + α, a control command for the heating pump CP may be generated so as to decrease the output of the heating pump CP. According to the modification example of FIG. 8, it is possible to avoid the output of the heating pump CP from changing frequently in a short time and to achieve the stabilization of the heating control of the heat medium.

[0082] Also, in the present embodiment, an example in which the control process of FIG. 6 for realizing the function of heating load equalization control is executed by the controller of the boiler BL1 located at the end of the connection configuration by daisy chain among the controllers 110 built in each of the boilers BL1 to BL4 has been described. However, this function may be provided to the controller 110 of the boiler BL4. Alternatively, separately from the controllers 110 of the boilers BL1 to BL4, a controller for heating load equalization control that is communicatively connected to each controller 110 may be provided.

[0083] Alternatively, when the controllers 110 of the boilers BL1 to BL4 are connected to a common bus (not shown) and can exchange data alternately, each controller 110 can individually execute the control process shown in FIG. 6 for each boiler BL by collecting the current heating load from the other controllers 110 (S210).

[0084] <Modification Example of the Configuration of Each Boiler> FIG. 9 shows a modification example of the configuration of the boiler BL shown in FIGS. 1 and 2. FIG. 9 shows an example in which the boiler BL is a hot water heater with heating function and hot water supply function (heat source machine).

[0085] Referring to Figure 9, the modified boiler BL# further includes, in addition to the configuration of boiler BL in Figure 3, a hot water heat exchanger 140, an inlet pipe 206 and an outlet pipe 210, a bypass pipe 209, and a bypass flow valve 170 with a flow rate adjustment function for hot water supply. The hot water heat exchanger 140 has a primary side path 141 and a secondary side path 142. The hot water heat exchanger 140, the inlet pipe 206 and the outlet pipe 210, the bypass pipe 209, and the bypass flow valve 170 with a flow rate adjustment function constitute one embodiment of the "hot water supply mechanism".

[0086] Furthermore, in the heating path of the heat transfer medium formed by the operation of the heating pump CP, the piping 203 in Figure 3 is divided into piping 203a from the output side of the primary heat exchanger 131 to the distribution valve 160, and piping 203b from the distribution valve 160 to the output terminal 102. The distribution valve 160 branches the path of the heat transfer medium from piping 203a into piping 203b leading to the output terminal 102 and piping 204 leading to the primary side path 141 of the hot water heat exchanger 140. This allows at least a portion of the heated heat transfer medium to be introduced into the hot water heat exchanger 140 and used for hot water supply. In addition, piping 205 is provided to connect the output side of the primary side path 141 to piping 201.

[0087] The distribution valve 160 is controlled by the controller 110. Depending on the opening of the distribution valve 160, the ratio of the flow rate in the path from pipe 203a to pipe 203b to the flow rate in the path from pipe 203a to pipe 204, that is, the distribution ratio η to the "hot water supply mechanism" relative to the total amount of heat transfer medium output from the heat exchanger 130, can be controlled.

[0088] The heat transfer medium introduced into the piping 204 by the distribution valve 160 is not output to the heating circulation path 50 outside the boiler BL# (Figures 1 and 2), but instead flows through the hot water heat exchanger 140 (primary path 141), and then joins the heating path of the heat transfer medium at the connection point 207 of piping 201 and 205, i.e., on the input side of the heat exchanger 130.

[0089] When the hot water tap 350 is opened, cold water is introduced from the inlet pipe 206 by the water pressure of tap water or the like. The inlet pipe 206 is connected to the input side of the secondary path 142 of the hot water heat exchanger 140 via the bypass flow valve 170. The outlet pipe 210 is connected to the output side of the secondary path 142 of the hot water heat exchanger 140. In the hot water heat exchanger 140, the cold water flowing through the secondary path 142 is heated by the heat of the heat transfer medium flowing through the primary path 141. As a result, hot water is output from the secondary path 142 to the outlet pipe 210.

[0090] The bypass pipe 209 is installed between the inlet pipe 206 and the outlet pipe 210, via the bypass flow valve 170, to form a bypass path for the hot water heat exchanger 140. Hot water at an appropriate temperature, which is a mixture of high-temperature water heated in the hot water heat exchanger 140 (secondary path 142) and low-temperature water that has passed through the bypass pipe 209, is supplied from the outlet pipe 210 to the hot water tap 350, etc.

[0091] The bypass flow valve 170 has both a function to control the ratio of the flow rate of the bypass pipe 209 to the flow rate of the inlet pipe 206, and a function to limit the flow rate of water entering the inlet pipe 206. For example, during the period immediately after the start of hot water supply when the hot water supply capacity is insufficient, the bypass flow valve 170 with the flow rate adjustment function can be controlled to suppress the flow rate of water entering the inlet pipe 206 in order to reduce the flow rate of hot water coming out.

[0092] The inlet pipe 206 is equipped with a temperature sensor 253 for detecting the incoming inlet water temperature Tw and a flow sensor 260. Furthermore, a temperature sensor 254 for detecting the high-temperature water temperature Th is located on the output side of the secondary path 142 of the hot water heat exchanger 140, and a temperature sensor 255 for detecting the hot water temperature To after mixing the high-temperature and low-temperature water is located downstream of the confluence point 214 with the bypass pipe 209 in the outlet pipe 210.

[0093] When the flow rate is detected by the flow sensor 260 in response to the opening of the hot water tap 350, the controller 110 executes hot water supply operation. During hot water supply operation, the distribution ratio η by the distribution valve 160 is controlled so that at least a portion of the heat transfer medium in the heating path is introduced into the hot water heat exchanger 140 (primary path 141).

[0094] When the heat transfer medium is being heated and the hot water supply operation is not being performed, the controller 110 controls the distribution valve 160 so that η = 0. Conversely, when the hot water supply operation is being performed, the controller 110 basically controls the distribution valve 160 so that η = 1.0.

[0095] In boiler BL#, during hot water supply operation, regardless of whether heating operation for heating is being performed, heating control of the heat transfer medium is performed to ensure at least the hot water supply capacity. The hot water supply capacity Gw required for hot water supply operation can be calculated using the following equation (2), with respect to the flow rate Qw detected by the flow sensor 260, the inlet water temperature Tw (temperature sensor 253), and the hot water supply set temperature To*, which is the set value of the hot water supply temperature To.

[0096] Gw = Qw · (To* - Tw) …(2) During hot water supply operation, the controller 110 can calculate the amount of heat G(S130) for controlling the heating of the heat transfer medium in a manner that ensures the necessary hot water supply capacity Gw as described above, rather than directly controlling the temperature of the heat transfer medium.

[0097] In boiler BL#, which has both heating and hot water supply functions, even during hot water supply operation, controlling the distribution valve 160 to the above ratio η < 1.0 makes it possible to output a portion of the heat transfer medium in the heating path to the heating circulation path 50 (Figures 1 and 2). For example, when there is surplus in hot water combustion (a state where a lot of cold water is flowing through the bypass pipe 209), the distribution valve 160 can be controlled to slightly open to the heating side, thereby reducing the heat exchange efficiency in the hot water heat exchanger 140 to a level where hot water supply capacity can be ensured while raising the temperature of the heat transfer medium. The determination of whether or not such control of the distribution valve 160 is possible is performed periodically.

[0098] However, during hot water supply operation, the heat transfer medium in the heating path is heated without temperature control, based on the amount of heat input from the "heating function (combustion burner 120 and heat exchanger 130)" minus the amount of heat consumed by hot water supply.

[0099] Therefore, for boiler BL#, it is inappropriate to have it participate in heating load equalization control during hot water supply operation, even when the heat transfer medium is being heated. Accordingly, for boiler BL# (Figure 9), which has a hot water supply function in addition to the heating function, it is preferable to perform heating load equalization control as shown in Figure 10.

[0100] Figure 10 is a flowchart illustrating the heating load equalization control process by boiler BL# shown in Figure 9. The control process shown in Figure 10 is repeatedly executed by the controller 110 of boiler BL#, which has a hot water supply function and constitutes boilers BL1 to BL4 shown in Figures 1 and 2, during the heating operation of the heat transfer medium.

[0101] The controller 110 determines in S410 whether boiler BL#, which is in heating operation, is in hot water supply operation. The processing in S410 can be performed based on the distribution ratio η by the distribution valve 160, the flow rate detected by the flow sensor 260, etc.

[0102] When hot water supply operation is in progress (when S410 determines YES), controller 110 sets the heating amount G(i) of boiler BL#, which is collected in S210 of the heating load equalization control (Figure 6), to 0 in S420, and decides in S430 not to participate in the heating load equalization control.

[0103] In this case, the controller 110 (BL1), which oversees the heating load equalization control, sets G(1)=0 for boiler BL1 and then executes the control process shown in Figure 6. On the other hand, the other controllers 110 (BL2~BL4) transmit G(i)=0, which was set in S420, via S310 in Figure 7. Also, in accordance with the decision in S430 not to participate in the heating load equalization control, no control commands for the heating pump CP are input in S320 and S330.

[0104] In contrast, when the controller 110 is not in hot water supply operation (when NO is determined in S410), it participates in heating load equalization control by executing the control process described in Figure 6 or Figure 7 in S440. This enables it to perform the same control operation as boiler BL in Figure 3.

[0105] By using the control process shown in Figure 10, even when some or all of the multiple boilers BL1 to BL4 are composed of boiler BL# which has a hot water supply function, the heating load equalization control described in this implementation can be properly executed to equalize the heating load of the heat transfer medium among multiple boilers during heating operation.

[0106] In this embodiment, the heat of combustion of gas was used as an example of the energy source for the "heating mechanism" of boilers BL and BL#, but the heat of combustion of any fuel can be used as the energy source.

[0107] Furthermore, although this embodiment mainly describes an example of control operation when all four boilers BL1 to BL4 are in heating operation of the heat transfer medium, it will be confirmed that even when two or three of the four boilers are in heating operation, the heating load equalization control according to this embodiment can be performed among those two or three boilers. That is, the heating load equalization control according to this embodiment can be applied to two or more heat source units that are in heating operation when any multiple heat source units (boilers) are connected to the heating circulation path 50, and some or all of those multiple heat source units are in heating operation.

[0108] Furthermore, in this invention, the method for selecting a heat source when performing heating operation using a portion of the multiple heat source units (boilers) described above is entirely arbitrary, and the heating load equalization control according to this embodiment can be applied to multiple heat source units during heating operation that have been selected by any arbitrary method.

[0109] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0110] 10 Heating system, 50 Heating circulation path, 51 Supply piping, 52a, 52b Return piping, 54, 55 Connection point (piping), 101 Input terminal, 102 Output terminal, 105 Boiler body, 106 Exhaust pipe, 110 Controller, 112 Memory, 115 Interface, 116 Communication unit, 117 Power supply circuit, 120 Combustion burner, 121 Flow control valve, 130 Heat exchanger, 131 Primary heat exchanger, 132 Secondary heat exchanger, 140 Hot water heat exchanger, 141 Primary side path, 142 Secondary side path, 160 Distribution valve, 170 Bypass flow valve, 195 Drain tank, 201~205 Piping, 206 Water inlet pipe, 207 Connection point, 209 Bypass pipe, 210 Hot water outlet pipes, 251, 252, 253, 254, 255 Temperature sensor, 260 Flow sensor, 350 Hot water taps, BL, BL1~BL4, BL♯ Boiler, CBL, CBL1, CBL2 Communication cable, CN1, CN2 Communication connector, CP, CP1~CP4 Heating pump, HP, HP1, HP2 Pump (heating terminal), HT, HT1, HTn Heating terminal, HTM, HTM1~HTMn Heating equipment.

Claims

1. It is a heating system, The system includes multiple heat source units connected to a circulation path for the heat transfer medium, which is used to circulate the heat transfer medium to the heating terminal. Each of the aforementioned multiple heat source units is The input terminal and output terminal connected to the aforementioned circulation path, A heating mechanism for raising the temperature of the heat transfer medium through which it is passed, This includes a heating pump that operates during the heating operation of the heat source unit and whose output during operation can be changed and controlled, The heating pump is arranged such that, during operation, the heat transfer medium introduced from the input terminal passes through the heating mechanism and is then output from the output terminal, forming a heating path with a flow rate that increases or decreases according to the output. The aforementioned heating system is The system further includes a control unit for performing heating load equalization control for two or more of the aforementioned multiple heat source units that are in heating operation, A heating system in which, in the heating load equalization control, the control unit sets a heating target value according to the average value of the current heating loads of each of the two or more heat source units, and generates a control command to reduce the output of the heating pump for heat source units whose current heating load is higher than the heating target value, while generating a control command to increase the output of the heating pump for heat source units whose current heating load is lower than the heating target value.

2. Each of the aforementioned plurality of heat source units includes a controller having a control function for the heating mechanism and the heating pump, The aforementioned multiple heat source units are connected in a daisy-chain configuration to enable data transmission and reception between the controllers of adjacent heat source units. The control unit is comprised of the controller of the first heat source unit located at either end of the daisy chain among the plurality of heat source units. The heating system according to claim 1, wherein the controller of each of the heat source units other than the first heat source unit among the plurality of heat source units controls the heating pump of the heat source unit in accordance with the control command generated by the controller of the first heat source unit when it is subject to the heating load equalization control.

3. Each of the aforementioned multiple heat source units is A hot water supply mechanism for heating incoming water and supplying hot water using the heat transfer medium heated by the aforementioned heating mechanism, The system further includes a distribution valve that controls the distribution ratio of the heat transfer medium heated by the heating mechanism to the hot water supply mechanism, The heating system according to claim 1, wherein the control unit excludes from the heating load equalization control any heat source unit among the two or more heat source units during the heating operation that has at least a portion of the heat transfer medium distributed to the hot water supply mechanism.

4. Each of the plurality of heat source units includes a controller having control functions for the heating mechanism, the heating pump, the hot water supply mechanism, and the distribution valve. The aforementioned multiple heat source units are connected in a daisy-chain configuration to enable data transmission and reception between the controllers of adjacent heat source units. The control unit is comprised of the controller of the first heat source unit located at either end of the daisy chain among the plurality of heat source units. The heating system according to claim 3, wherein the controller of each of the heat source units other than the first heat source unit among the plurality of heat source units controls the heating pump of the heat source unit in accordance with the control command generated by the controller of the first heat source unit when it is subject to the heating load equalization control.

5. Each of the aforementioned plurality of heat source units includes a controller having a control function for the heating mechanism and the heating pump, The heating system according to claim 1, wherein each controller calculates the heating load at each heat source according to the product of an estimated flow rate of the heat medium in the heating path based on the current output of the heating pump, and the temperature difference between a measured temperature of the heat medium introduced into the heating path and the output set temperature of the heat medium derived from the heating mechanism.

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