JP4838654B2 - Pipe line freezing prevention method and cogeneration system - Google Patents

Description

  The present invention relates to a pipeline freezing prevention method and a cogeneration system.

Conventionally, a power generation device that generates electricity and heat, a hot water storage tank that stores hot water that has absorbed heat generated by the power generation device, and a pipe that circulates water between the power generation device and the hot water storage tank. A cogeneration system is known. Such a cogeneration system is known to have a freeze prevention function for preventing freezing of water in the pipeline. For example, Patent Document 1 below discloses a cogeneration system that can prevent freezing of water in a pipeline by using hot water stored in a hot water tank without adding a heater such as a heater. Has been.
JP 2004-60980 A

  However, particularly in cold regions, it is not possible to completely prevent freezing of the water in the pipe line simply by using the hot water stored in the hot water tank. In particular, when the function of the power generation device is stopped, it is difficult to exert the effect of preventing freezing for a long time such as at night. In order to cope with this problem, it is conceivable to heat the pipe directly with a heater such as a heater. However, in order to effectively prevent freezing, it is necessary to install a heater over the entire pipeline, and power consumption tends to increase.

  The present invention has been made in view of the above problems, and provides a pipe freezing prevention method and a cogeneration system that can more reliably prevent freezing of water in the pipe while reducing power consumption. For the purpose.

The pipe freezing prevention method of the present invention is provided to form a circulation path between a power generation device that generates electric power and heat, a hot water storage tank that stores water, and the power generation device to the hot water storage tank. A pipe freezing prevention method in a cogeneration system comprising a pipe for sending the absorbed water into the hot water storage tank, and the environment is detected by a temperature sensor provided in at least one of the power generator and the hot water storage tank. A temperature acquisition step for acquiring temperature, a temperature determination step for determining whether or not the environmental temperature acquired in the temperature acquisition step is equal to or lower than a predetermined value, and the environmental temperature is determined to be lower than or equal to a predetermined value in the temperature determination step. If the environmental temperature is determined to be equal to or lower than a predetermined value in the heating control step of heating the water in the pipeline with a heater and the temperature determination step, A circulation control step by a pump provided in the middle of the road circulating water in the conduit, a tube for acquiring the two temperatures of the conduit by the first and second temperature sensors provided at different sites conduit A flow temperature acquisition step, and in the circulation control step, the flow rate of water in the pipeline is controlled so that a difference between the two temperatures acquired in the pipeline temperature acquisition step is a predetermined value or less. And

Moreover, the cogeneration system of the present invention is provided so as to form a circulation path between a power generation device that generates electric power and heat, a hot water storage tank that stores water, and from the power generation device to the hot water storage tank. A cogeneration system including a pipe for sending the absorbed water into the hot water storage tank, and acquiring the environmental temperature by a temperature sensor provided in at least one of the power generation device and the hot water storage tank Means, a temperature determining means for determining whether or not the environmental temperature acquired by the temperature acquiring means is equal to or lower than a predetermined value, and a pipe line when the environmental temperature is determined to be lower than or equal to a predetermined value by the temperature determining means. A heating control means that heats the water in the heater with a heater, and a pipe provided by a pump provided in the middle of the pipe line when the temperature judgment means judges that the environmental temperature is below a predetermined value. Comprising of a circulation control means for circulating the water, and a conduit temperature acquisition means for acquiring two temperatures of the conduit by the first and second temperature sensors provided at different sites conduit, circulation control means The flow rate of water in the pipeline is controlled so that the difference between the two temperatures acquired by the pipeline temperature acquisition means is a predetermined value or less .

  According to such a pipeline freezing prevention method and a cogeneration system, when the environmental temperature is equal to or lower than a predetermined value, water in the pipeline is heated by a heater and a pump provided in the middle of the pipeline. Heated water is circulated through the entire pipeline. Thereby, it can prevent effectively that the water in a pipe line freezes, without providing a heater in wide range. In addition, it is not necessary to expand the heater installation range, and the power consumption of the heater can be reduced.

  In this case, the flow rate of water in the pipeline is controlled by controlling the pump so that the difference between the pipeline temperatures measured at two locations is not more than a predetermined value. Therefore, the flow rate of the water heated by the heater can be adjusted according to the temperature condition of the pipe line, and the heat of the heater can be flowed to the entire pipe line without unevenness.

  In the pipe freezing prevention method of the present invention, it is preferable to control the heating amount by the heater so that the two temperatures are equal to or higher than a predetermined value in the heating control step.

  Moreover, in the cogeneration system of this invention, it is preferable that a heating control means controls the heating amount by a heater so that two temperature may become more than predetermined value.

  If it carries out like this, the heating amount by a heater will be controlled so that the pipe line temperature measured by two places becomes all more than predetermined value. Therefore, the temperature of different parts in the pipe line can be raised to a certain temperature or more, and freezing of water in the pipe line can be more reliably prevented.

  According to such a pipe freezing prevention method and a cogeneration system, it is possible to more reliably prevent water in the pipe from being frozen while reducing power consumption.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Moreover, in the following description, “water” means all liquid water regardless of the water temperature.

  First, the configuration of the cogeneration system 1 according to the embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a diagram illustrating a schematic configuration of a cogeneration system 1 according to the embodiment. FIG. 2 is a diagram showing a hardware configuration of the main control device 15 and the sub control device 26 shown in FIG.

  The cogeneration system 1 is a system that generates electric power by fuel cell power generation and uses exhaust heat during power generation for air conditioning and hot water supply. The cogeneration system 1 includes a fuel cell power generation device 10, a hot water storage unit 20, and a hot water heater 53 capable of heating water sent from the hot water storage unit 20. Further, the cogeneration system 1 heats the commercial power system 50 and the electric equipment EI through the power line 51, the water supply system 52 through the water supply line 30, the hot water supply line 31 and the hot water supply 53. Each is connected to the device HI. In addition, the cogeneration system 1 is provided with a circulation line 32 for circulating water in the cogeneration system 1.

  The water supply line 30 includes a water supply line 30 a that connects the water supply system 52 and the hot water three-way valve 25, and a water supply line that branches from the water supply line 30 a and connects to the lower part of the hot water tank 21. 30b. The hot water discharge pipe 31 is connected to the thermal equipment HI from the upper part of the hot water storage tank 21 through the hot water three-way valve 25 and the hot water heater 53.

  The circulation pipe 32 is connected to the hot water tank 21 through a reverse pipe line 32 a extending from the lower part of the hot water tank 21 to the heat exchanger 12 in the fuel cell power generator 10, and a three-way valve (switching valve) 24 for circulation from the heat exchanger 12. It consists of a forward line 32b that reaches the upper part and a bypass line 32c that bypasses the hot water storage tank 21 from the circulation three-way valve 24 and is connected to the reverse line 32a. A part of the reverse direction pipe 32 a and a part (exposed portion) of the forward direction pipe 32 b between the fuel cell power generation apparatus 10 and the hot water storage unit 20 are exposed to the outside from the fuel cell power generation apparatus 10 and the hot water storage unit 20. For example, it is exposed to an external environment such as the ground or a wall surface of a house.

  A pipe temperature sensor 41 (first temperature sensor) and a pipe temperature sensor 42 (second temperature sensor) are attached to the outer periphery of the forward duct 32b, and both measure the temperature of the forward duct 32b. To do. The pipe temperature sensor 41 is attached in the vicinity of the fuel cell power generator 10 in the exposed part of the forward direction pipe 32b, and the pipe temperature sensor 42 is attached in the vicinity of the hot water storage unit 20 in the exposed part. ing. Thermocouples and thermistors are used for the pipe temperature sensors 41 and 42, but the elements constituting the pipe temperature sensors are not limited to this.

  The fuel cell power generation apparatus 10 can be operated by electric power supplied via the commercial power system 50, and includes a generator 11, a heat exchanger 12, an FC heater (heater) 13, a pump 14, and a main controller 15.

  The generator 11 is a device that generates power (generates electric power) using a built-in fuel cell and generates heat along with power generation. The generator 11 outputs the generated power to the electric equipment EI through the power line 51 and moves the heat generated with the power generation to the heat exchanger 12.

  The heat exchanger 12 absorbs heat generated in the generator 11 and transmits the heat to water circulating in the heat exchanger 12. Specifically, the heat exchanger 12 transfers heat to the water flowing in through the reverse line 32a, and as a result, the water in which the heat is absorbed flows out to the forward line 32b. Therefore, the water that has absorbed the heat generated in the fuel cell power generator 10 is sent to the hot water storage tank 21 by the heat exchanger 12 and the circulation pipe 32.

  The FC heater 13 is a heating element such as a strip-shaped resistor, and is attached so as to be wound around the outer peripheral portion of the forward duct 32 b in the fuel cell power generator 10. The FC heater 13 energized by the commercial power system 50 via a transmission line (not shown) heats the water flowing in the circulation line 32 by heat generated by the energization.

  The pump 14 is attached in the middle of the reverse direction pipe 32 a in the fuel cell power generator 10. For example, the pump 14 is configured to have a spiral impeller inside thereof, and the water in the circulation pipe 32 is circulated toward the heat exchanger 12 by rotating the impeller. The pump 14 can change the rotation speed of the impeller during operation under the control of the main controller 15.

  The main control device 15 controls the operation of the fuel cell power generation device 10. As shown in FIG. 2A, the main control device 15 includes a CPU 61, a main storage unit 62 constituted by a ROM or a RAM, a communication control unit 63 that controls communication with a sub-control device 26 described later, and a fuel cell power generator 10 has an interface unit 64 for inputting / outputting signals to / from components other than the main control device 15 constituting the system 10.

  The hot water storage unit 20 includes a hot water storage tank 21, an air temperature sensor (temperature sensor) 22, a hot water storage tank heater (heater) 23, a three-way valve 24 for circulation, a three-way valve 25 for hot water, and a sub-control device 26.

  The hot water storage tank 21 is a tank that stores the water heat-exchanged in the heat exchanger 12. The hot water storage tank 21 is connected to the water supply line 30b and the reverse direction pipe 32a in the lower part, and is connected to the hot water supply line 31 and the forward direction line 32b in the upper part. With such a connection configuration, water stored in the hot water storage tank 21 by being supplied from the water supply system 52 is sent to the heat exchanger 12. In addition, the water sent from the heat exchanger 12 is stored in the hot water storage tank 21, and the water stored in the hot water storage tank 21 is supplied to the thermal equipment HI via the hot water heater 53. Water with a high temperature sent from the heat exchanger 12 flows into the hot water tank 21 from the upper part of the hot water tank 21, while water with a low temperature sent from the water supply system 52 stores hot water from the lower part of the hot water tank 21. It flows into the tank 21. Therefore, the water stored in the hot water tank 21 forms a stratification.

  The air temperature sensor 22 is provided inside the casing of the hot water storage unit 20 and measures the ambient temperature around the hot water storage unit 20. An opening (not shown) is formed in a portion of the housing of the hot water storage unit 20 where the air temperature sensor 22 is attached, and the air temperature sensor 22 measures the environmental temperature through the opening. Although the thermocouple, thermistor, etc. are used for the temperature sensor 22, the element which comprises an air temperature sensor is not limited to this.

  The hot water tank heater 23 is a heating element such as a strip-shaped resistor, and is attached so as to be wound around the outer peripheral portion of the reverse pipe line 32a. The hot water tank heater 23 energized by the commercial power system 50 via a transmission line (not shown) heats the water flowing in the circulation line 32 by the heat generated by the energization.

  The three-way valve 24 for circulation is provided at a branch point to the bypass line 32c in the forward direction line 32b. The circulation three-way valve 24 is controlled to switch the flow path so that the water flowing from the heat exchanger 12 side in the forward direction pipe 32b flows to either the hot water tank 21 or the bypass line 32c.

  The hot water three-way valve 25 is provided at a branch point of the hot water pipe 31 with the tap water pipe 30a. The hot-water three-way valve 25 switches the flow path so that either water supplied from the hot water storage tank 21 or the water supply system 52 is sent to the thermal equipment HI via the water heater 53.

  The sub-control device 26 can be operated by electric power transmitted from the commercial power system 50 and controls the hot water storage unit 20. As shown in FIG. 2 (b), the sub-control device 26 constitutes a CPU 71, a main storage unit 72 composed of ROM or RAM, a communication control unit 73 that controls communication with the main control device 15, and a hot water storage unit 20. An interface unit 74 for inputting / outputting signals to / from components other than the sub-control device 26 is provided.

  Next, functional configurations of the main control device 15 and the sub control device 26 will be described with reference to FIGS. 3 and 4. 3 and 4 are diagrams showing functional configurations of the main control device 15 and the sub control device 26.

  The main control device 15 includes a main communication unit 151, a pipe temperature acquisition unit (pipe temperature acquisition unit) 152, a temperature determination unit (temperature determination unit) 153, an FC heater control unit (heating control unit) 154, and a pump control unit. (Circulation control means) 155, temperature difference determination section (circulation control means) 156, and heating amount determination section (heating control means) 157. Each function of the main control device 15 causes the CPU 61 and the main storage unit 62 to read predetermined software, operates the communication control unit 63 or the interface unit 64 under the control of the CPU 61, and reads data from the main storage unit 62. And writing.

  The sub-control device 26 includes a sub-side communication unit 261, an air temperature acquisition unit (temperature acquisition unit) 262, a hot water tank heater control unit (heating control unit) 263, a circulation three-way valve control unit (flow path control unit) 264, and a spare unit. A temperature determination unit (temperature determination means) 265 is provided. Each function of the sub-control device 26 causes the CPU 71 and the main storage unit 72 to read predetermined software, operates the communication control unit 73 or the interface unit 74 under the control of the CPU 71, and reads data from the main storage unit 72. And writing.

  The main communication unit 151 monitors the communication state between the main control device 15 and the sub control device 26 by transmitting and receiving control signals to and from the sub communication unit 261 via the communication control unit 63. Specifically, first, the main communication unit 151 transmits a control signal to the sub communication unit 261, and the main communication unit 151 receives a response signal transmitted by the sub communication unit 261 according to the control signal. If it is possible, it is determined that communication between the main control device 15 and the sub control device 26 is possible. In this case, the main communication unit 151 outputs a communication monitoring signal indicating “communicable” to the temperature determination unit 153 and the heating amount determination unit 157. On the other hand, if the main communication unit 151 cannot receive the response signal within a predetermined time, it is determined that communication between the main control device 15 and the sub control device 26 is impossible, A communication monitoring signal indicating “communication impossible” is output to the temperature determination unit 153 and the heating amount determination unit 157. Note that the communication between the main communication unit 151 and the sub communication unit 261 is performed by wireless communication, for example, but the communication method is not limited to this.

  The sub communication unit 261 monitors the communication state via the communication control unit 73 in the same manner as the main communication unit 151. Specifically, first, the sub communication unit 261 transmits a control signal to the main communication unit 151, and the sub communication unit 261 receives a response signal transmitted by the main communication unit 151 in response to the control signal. If it is possible, it is determined that communication between the sub-control device 26 and the main control device 15 is possible. In this case, the secondary communication unit 261 outputs a communication monitoring signal indicating “communication is possible” to the standby temperature determination unit 265. On the other hand, when the sub communication unit 261 cannot receive the response signal within the predetermined time, it is determined that communication between the sub control device 26 and the main control device 15 is impossible, A communication monitoring signal indicating “communication impossible” is output to spare temperature determination unit 265.

  Hereinafter, functions of the main control device 15 and the sub control device 26 will be described separately for cases where communication between the main control device 15 and the sub control device 26 is possible and cases where communication is impossible. First, each function when communication is possible between the main controller 15 and the sub controller 26 will be described with reference to FIG. In the following description, the temperature determination unit 153 and the heating amount determination unit 157 in the case where it is recognized that communication is possible based on the communication monitoring signal input from the main communication unit 151 or the sub communication unit 261. The function of the preliminary temperature determination unit 265 is shown.

  The temperature acquisition unit 262 acquires the environmental temperature that is constantly or periodically input from the temperature sensor 22 and stores it in the main storage unit 72 or the like. For example, the latest environmental temperature T1 (° C.) measured by the temperature sensor 22 is held as data. In addition, the acquisition method of environmental temperature is not limited to this, For example, the temperature acquisition part 262 may start the temperature sensor 22 regularly and acquire itself.

  The pipeline temperature acquisition unit 152 acquires the pipeline temperature that is constantly or periodically input from the pipeline temperature sensor 41 and the pipeline temperature sensor 42, and stores the pipeline temperature in the main storage unit 62 or the like. For example, the pipe temperature T2 (° C.) measured by the pipe temperature sensor 41 and the pipe temperature T3 (° C.) measured by the pipe temperature sensor 42 measured at the same time are held as data. In addition, the acquisition method of pipe temperature is not limited to this, For example, the pipe temperature acquisition part 152 may start the pipe temperature sensor 41 and the pipe temperature sensor 42 regularly, and may acquire it itself.

  The temperature determination unit 153 reads out and holds in advance from the main storage unit 62 the maximum value of the environmental temperature (hereinafter referred to as “environmental temperature threshold”) at which the water in the pipeline is likely to freeze. Further, the temperature determination unit 153 periodically acquires environmental temperature data held by the air temperature acquisition unit 262 by receiving it from the sub-control device 26 via the communication control unit 64, and the environmental temperature data is stored in the environmental temperature threshold (predetermined value). Value) or less. If the environmental temperature data is equal to or lower than the environmental temperature threshold value, the freeze prevention instruction signal for instructing the control for preventing the pipe freezing is sent to the FC heater control unit 154, the hot water tank heater control unit 263, the pump control unit 155, and the like. Output to the three-way valve control unit 264 for circulation. For example, if the relationship between the acquired environmental temperature data T1 (° C.) and the environmental temperature threshold value Tf (° C.) is T1 ≦ Tf, a freeze prevention instruction signal is output. If the relationship is T1> Tf, nothing is output. do not do.

  The FC heater control unit 154 controls to start energization of the FC heater 13 when receiving the freeze prevention instruction signal from the temperature determination unit 153, and heats the water in the circulation line 32. Further, the FC heater control unit 154 controls to stop energization of the FC heater 13 when receiving a stop signal from a heating amount determination unit 157 described later.

  The hot water tank heater control unit 263 controls to start energization in the hot water tank heater 23 when receiving the freeze prevention instruction signal from the temperature determination unit 153, and heats the water in the circulation line 32. The hot water tank heater control unit 263 controls to stop energization in the hot water tank heater 23 when a stop signal is received from a heating amount determination unit 157 described later.

  The pump control unit 155 controls to start driving the pump 14 when receiving the freeze prevention instruction signal from the temperature determination unit 153. In addition, the pump control unit 155 reads and holds information corresponding to the rotational speed of the pump 14 from the main storage unit 62 in advance, and when receiving a flow rate increase signal described later, the pump 14 at the rotational speed corresponding to the signal. The drive of the pump 14 is controlled so as to rotate. For example, the pump control unit 155 holds an increment ΔR (rpm) corresponding to the flow rate increase signal. When the flow rate increase signal is received, the drive of the pump 14 is controlled so as to increase the rotational speed of the pump 14 by ΔR (rpm).

  When the circulation three-way valve control unit 264 receives the freeze prevention instruction signal from the temperature determination unit 153, the water heated by the FC heater 13 and the hot water tank heater 23 is transferred from the reverse line 32a and the forward line 32b. When circulating through the circulation path, the circulation three-way valve 24 is switched so as to flow into the bypass pipeline 32c from the forward pipeline 32b.

  The temperature difference determination unit 156 periodically acquires the two pipe temperature data held by the pipe temperature acquisition unit 152, calculates the difference between these pipe temperatures, and the rotational speed of the pump 14 based on the value. Is output to the pump control unit 155. For this purpose, the temperature difference determination unit 156 reads out and holds a reference value (predetermined value) for changing the flow rate of the circulation pipe 32 from the main storage unit 62 in advance.

  For example, the temperature difference determination unit 156 acquires the pipe temperature data T2 (° C.) and T3 (° C.) from the pipe temperature acquisition unit 152, calculates | T2−T3 | (° C.), and the reference value Tc ( C)) is read out. Then, it is determined whether or not the pipe temperature data T2 (° C.) and T3 (° C.) satisfy the relationship of | T2-T3 |> Tc. At this time, if the relationship is satisfied, a flow rate increase signal indicating an instruction to increase the flow rate is output to the pump control unit 155. If the relationship is not satisfied, nothing is done. That is, the temperature difference determination unit 156 controls the flow rate of water in the circulation line 32 so that the difference between the two temperatures of the circulation line 32 is equal to or less than the reference value.

  The heating amount determination unit 157 reads out and holds in advance from the main storage unit 62 the minimum value of the pipe temperature (hereinafter referred to as “circulation guarantee temperature”) at which the water in the circulation pipe 32 is not likely to freeze. Further, the heating amount determination unit 157 acquires two pipe temperature data held by the pipe temperature acquisition unit 152, and compares each pipe temperature data with the circulation guarantee temperature (predetermined value). If at least one pipe temperature data is less than the circulation guarantee temperature, it is determined that the energization of the FC heater 13 and the hot water tank heater 23 is continued. If all the pipe temperature data are equal to or higher than the circulation guarantee temperature, the FC is determined. It is determined that the energization of the heater 13 and the hot water tank heater 23 is stopped.

  When it is determined that the energization of the FC heater 13 and the hot water tank heater 23 is stopped, the heating amount determination unit 157 outputs a stop signal for stopping the energization to the FC heater control unit 154 and the hot water tank heater control unit 263, respectively. For example, if the relationship between the acquired pipe temperature data T2 (° C.) and T3 (° C.) and the circulation guarantee temperature Tg (° C.) is “T2 ≧ Tg and T3 ≧ Tg”, a stop signal is output. If “T2 <Tg or T3 <Tg”, nothing is output. That is, the heating amount determination unit 157 controls the heating amounts by the FC heater 13 and the hot water tank heater 23 so that the two temperatures of the circulation pipe 32 are equal to or higher than the circulation guarantee temperature.

  Next, each function when communication between the main control device 15 and the sub control device 26 is impossible will be described using FIG. 4. In the following description, the temperature determination unit 153, the heating amount determination unit 157, and the heating amount determination unit 157 in the case where it is recognized that communication is impossible by the communication monitoring signal input from the main communication unit 151 or the sub communication unit 261. The function of the preliminary temperature determination unit 265 is shown. Further, the description of the parts overlapping with the functions of the main control device 15 and the sub control device 26 described above will be omitted.

  The temperature determination unit 153 acquires the two pipe temperature data held by the pipe temperature acquisition unit 152, and compares each pipe temperature data with the environmental temperature threshold. If at least one pipe temperature data is equal to or lower than the environmental temperature threshold, a freeze prevention instruction signal is output to the FC heater control unit 154 and the pump control unit 155. For example, if the relationship between the acquired pipe temperature data T2 (° C.) and T3 (° C.) and the environmental temperature threshold value Tf (° C.) is “T2 ≦ Tf or T3 ≦ Tf”, the freeze prevention instruction signal is output. If the relationship is “T2> Tf and T3> Tf”, nothing is output.

  The preliminary temperature determination unit 265 operates only when communication between the main control device 15 and the sub control device 26 is impossible. The preliminary temperature determination unit 265 reads and holds the environmental temperature threshold value from the main storage unit 72 in advance. The preliminary temperature determination unit 265 acquires the environmental temperature data held by the air temperature acquisition unit 262, and compares the environmental temperature data with the environmental temperature threshold. If the environmental temperature data is equal to or lower than the environmental temperature threshold value (predetermined value), a freeze prevention instruction signal similar to that output by the temperature determination unit 153 is output to the hot water tank heater control unit 263 and the circulation three-way valve control unit 264. To do. For example, if the relationship between the acquired environmental temperature data T1 (° C.) and the environmental temperature threshold value Tf (° C.) is T1 ≦ Tf, a freeze prevention instruction signal is output. If the relationship is T1> Tf, nothing is output. do not do.

  The hot water tank heater control unit 263 controls to start energization in the hot water tank heater 23 when receiving the freeze prevention instruction signal from the preliminary temperature determination unit 265, and heats the water in the circulation line 32.

  When the circulation three-way valve control unit 264 receives the freeze prevention instruction signal from the preliminary temperature determination unit 265, the water heated by at least the hot water tank heater 23 includes the reverse line 32a and the forward line 32b. When circulating through the circulation path, the circulation three-way valve 24 is switched so as to flow into the bypass pipeline 32c from the forward duct 32b.

  The heating amount determination unit 157 acquires the two pipe temperature data held by the pipe temperature acquisition unit 152, and compares each pipe temperature data with the circulation guarantee temperature. At this time, if at least one pipe temperature data is less than the circulation guarantee temperature, it is determined that the energization of the FC heater 13 is continued. On the other hand, if all the pipe temperature data are equal to or higher than the circulation guarantee temperature, it is determined that the energization of the FC heater 13 is stopped, and a stop signal is output to the FC heater control unit 154. For example, if the relationship between the acquired pipe temperature data T2 (° C.) and T3 (° C.) and the circulation guarantee temperature Tg (° C.) is “T2 ≧ Tg and T3 ≧ Tg”, a stop signal is output. If “T2 <Tg or T3 <Tg”, nothing is output.

  Next, operation | movement of the cogeneration system 1 which concerns on this embodiment is demonstrated, referring FIG. FIG. 5 is a sequence diagram showing the operation of the cogeneration system 1 shown in FIG.

  First, the environmental temperature is acquired by the air temperature acquisition unit 262 of the sub-control device 26, and is stored as environmental temperature data (step S1, temperature acquisition step). This environmental temperature data is read by the temperature determination unit 153 constituting the main controller 15 (step S2). And it is judged by the temperature judgment part 153 whether the acquired environmental temperature data is below an environmental temperature threshold value (step S3, temperature judgment step).

  Here, when the temperature determination unit 153 determines that the environmental temperature data is equal to or lower than the environmental temperature threshold value (step S3; YES), the FC heater control unit 154 starts energization of the FC heater 13 on the main controller 15 side. At the same time (step S5, heating control step), the pump 14 is driven by the pump controller 155 (step S6, circulation control step). At the same time, in order to control the hot water tank heater 23 and the three-way valve 24 for circulation, the temperature determination unit 153 transmits a freeze prevention instruction signal to the sub-control device 26 (step S4). In the sub-control device 26 that has received this signal, the hot water tank heater control unit 263 starts energizing the hot water tank heater 23 (step S7, heating control step). In addition, the circulation three-way valve control unit 264 switches the circulation three-way valve 24 so that the heated water flows from the forward direction pipe 32b to the bypass line 32c (step S8, flow path control step).

  Thereafter, two pipeline temperatures are acquired by the pipeline temperature acquisition unit 152 of the main controller 15 (step S9, pipeline temperature acquisition step). There are the following two types of control based on these pipe line temperatures. As one control, first, the temperature difference determination unit 156 determines how to set the flow rate of water in the circulation line 32 (step S10, circulation control step). Here, when the temperature difference determination unit 156 determines that the flow rate in the circulation pipe 32 is to be increased (step S10; YES), the rotation speed of the pump 14 is increased by the pump control unit 155 on the main controller 15 side. (Step S11, circulation control step).

  As the other control, the heating amount determination unit 157 controls the heating amount of the FC heater 13 and the hot water tank heater 23 (step S12, heating control step). Here, when the heating amount determination unit 157 determines to stop the energization of these heaters (step S12; YES), the FC heater control unit 154 stops energization of the FC heater 13 on the main controller 15 side ( Step S14, heating control step). At the same time, in order to control the hot water tank heater 23, the heating amount determination unit 157 transmits a stop signal to the sub-control device 26 (step S13). In the sub-control device 26 that has received this signal, the hot water tank heater control unit 263 stops energization of the hot water tank heater 23 (step S15, heating control step).

  According to this embodiment, when the environmental temperature measured by the air temperature sensor 22 is equal to or lower than the environmental temperature threshold, energization of the FC heater 13 and the hot water tank heater 23 is started, and the water in the circulation line 32 is heated. The At the same time, the pump 14 is driven, and the heated water circulates in the circulation line 32. Thereby, it can prevent that the water in the circulation line 32 freezes.

  Further, since the heated water flows in the circulation line 32, it is not necessary to provide a heater in the entire circulation line 32. Although a part of the backward pipe 32a and a part of the forward pipe 32b are exposed from the fuel cell power generation device 10 and the hot water storage unit 20 and are in direct contact with the outside air, the water in the pipe is likely to freeze. Since the heated water also flows through the exposed portion, it is not necessary to cover the exposed portion with a heater. Therefore, it is not necessary to expand the installation range of the FC heater 13 and the hot water tank heater 23, and the power consumption of the heater consumed in the entire cogeneration system 1 can be reduced.

  Further, according to the present embodiment, the pipe temperature sensors 41 and 42 measure the pipe temperature of the forward pipe 32b, and it is determined whether or not the absolute value of the difference between the pipe temperatures exceeds the reference value. Is done. If the absolute value exceeds the reference value, the pump 14 is controlled so that the heated water flows at a flow rate larger than the flow rate. Therefore, the flow rate of the water heated by the FC heater 13 and the hot water tank heater 23 can be adjusted according to the temperature condition of the circulation line 32, and the heated water can flow through the circulation line 32 without any bias. Is possible.

  Further, since the flow rate of the heated water can be adjusted according to the temperature condition of the circulation pipe 32, the distance between the fuel cell power generator 10 and the hot water storage unit 20 (the length of the reverse pipes 32a and 32b). Even if it is indefinite, the freeze prevention control can be performed dynamically.

  Further, according to the present embodiment, the FC heater 13 and the hot water tank heater 23 are energized until all of the pipe temperatures measured by the pipe temperature sensors 41 and 42 are equal to or higher than the circulation guarantee temperature. And when all of these pipe line temperatures become more than a circulation guarantee temperature, electricity supply to FC heater 13 and hot water tank heater 23 is stopped. That is, the heating amounts by the FC heater 13 and the hot water tank heater 23 are controlled so that the pipe line temperatures measured at two locations are all equal to or higher than the circulation guarantee temperature. Therefore, the temperature of the water flowing in the circulation line 32 can be raised to the circulation guarantee temperature or more, and the circulation line 32 can be more reliably prevented from freezing. Moreover, since it is not necessary to energize the FC heater 13 and the hot water tank heater 23 more than necessary, the power consumption of the heater consumed in the entire cogeneration system 1 can be further reduced. Furthermore, since the energization of the FC heater 13 and the hot water tank heater 23 can be controlled in accordance with the temperature condition of the circulation pipe 32, the freezing prevention is dynamically prevented even if the distance between the fuel cell power generation device 10 and the hot water storage unit 20 is indefinite. And the heating device can be controlled.

  Moreover, according to this embodiment, when the water in the circulation line 32 is circulated by the pump 14, the three-way valve for circulation 24 is controlled so as to pass from the forward line 32b to the bypass line 32c. Therefore, the water heated by the FC heater 13 and the hot water tank heater 23 only circulates in the reverse direction pipe 32a, the forward direction pipe 32b, and the bypass line 32c, and does not pass through the hot water tank 21. Therefore, it is possible to prevent the stratification of the water stored in the hot water tank 21 from falling and the water temperature from decreasing.

  In addition, since the flow path is switched in this way, the distance in which the water heated by the FC heater 13 and the hot water tank heater 23 circulates is shortened, so that the water in the circulation line 32 including the exposed portion that comes into contact with the outside air is removed. It is possible to heat to a circulation guarantee temperature without fear of freezing at an early stage. Therefore, the power consumption of the heater consumed in the entire cogeneration system 1 can be further reduced.

  Further, according to the present embodiment, the main control device 15 and the sub control device 26 are provided as control means, and these control devices are distributed to manage the cogeneration system 1. Therefore, even if a failure occurs in one of the control devices as a whole, the other control device detects the inability to communicate and controls each device in the fuel cell power generation device 10 or the hot water storage unit 20 incompletely. can do. Also, when a failure occurs only in communication between the main control device 15 and the sub-control device 26, both control devices detect the failure, and in each of the fuel cell power generation device 10 or the hot water storage unit 20 Each device can be controlled. Therefore, it is possible to improve fault tolerance regarding the management of the cogeneration system 1.

  The present invention has been described in detail based on the embodiments. However, the present invention is not limited to the above embodiment. The present invention can be modified in various ways as described below without departing from the scope of the invention.

  In the above embodiment, the flow rate of water in the circulation line 32 is controlled by controlling the pump 14 based on the difference in the pipe temperature measured by the pipe temperature sensors 41 and 42. It does not have to be done.

  Moreover, in the said embodiment, although the temperature sensor 22 was provided inside the housing | casing of the hot water storage unit 20, the opening part which is not shown in figure was formed in the part to which the air temperature sensor 22 is attached among the said housing | casing, The form is not limited to this. For example, the ambient temperature in the hot water storage unit 20 may be measured without providing the opening, or an air temperature sensor may be provided outside the hot water storage unit 20, or may be provided on the fuel cell power generation device 10 side. .

  Further, the installation location and the number of installation of the heater are not limited to the above embodiment. For example, it may be provided only in one of the fuel cell power generation apparatus 10 and the hot water storage unit 20, or the heater may be provided in the hot water storage tank 21, the heat exchanger 12 and the like instead of the pipe line. In short, it suffices if a heater is provided on the water flow path in the cogeneration system 1.

  The installation location of the temperature sensor for measuring the pipe temperature is not limited to the above embodiment, and may be provided in the fuel cell power generation apparatus 10 or the hot water storage unit 20, for example. Further, the temperature sensor may be provided so that the detection end of the temperature sensor is exposed in the pipeline, and the temperature sensor may measure the temperature of water in the pipeline instead of the temperature of the pipeline. When a temperature sensor is provided to measure the temperature of water in the pipeline, the flow rate control of the water in the circulation pipeline 32 and the heater energization continuation / stop control described above are performed in the measured pipeline. The same is done based on the temperature of the water. Further, the number of temperature sensors provided in the pipeline is not limited.

  In the above embodiment, the main control device 15 and the sub control device 26 are provided as control means. However, the control means is not limited to this, and for example, the control means is not distributed to a plurality of control devices. All of the above functions may be implemented in one control device.

  In the above embodiment, when the absolute value of the difference between the two pipe temperatures exceeds the reference value, the flow rate of water in the circulation pipe 32 is increased by increasing the rotation speed of the pump 14 by ΔR (rpm). However, the control of the flow rate of water in the pipe line is not limited to this. For example, the number of rotations of the pump 14 may be increased in multiple stages, and the increase may be changed according to the difference between the two pipe temperatures. As an example, ΔRa (rpm) and ΔRb (rpm) are provided as increments of the rotational speed of the pump 14 (here, ΔRa <ΔRb). When the difference between the two pipe temperatures is very large, the pump 14 If the rotational speed is increased by ΔRb and the difference between the two pipe temperatures is not so large, the rotational speed may be increased by ΔRa. In the above embodiment, nothing is performed when the absolute value of the difference between the two pipe temperatures is within the reference value. For example, the circulation pipe is reduced by reducing the rotation speed of the pump 14 by ΔRc (rpm). The flow rate of water in the path 32 may be decreased.

  In the above embodiment, the heating amount determination unit 157 determines that the energization of the FC heater 13 and the hot water tank heater 23 is stopped if all the pipe temperature data are equal to or higher than the circulation guarantee temperature. Control in the case where is greater than or equal to a predetermined value is not limited to this. For example, when all the pipe temperatures are equal to or higher than a predetermined value, the energization power of the heater may be decreased or intermittent operation may be performed.

  Moreover, in the said embodiment, although the fuel cell power generation device 10 was used in order to generate | occur | produce electric power and heat, the structure of a power generation device is not limited to this. For example, electric power and heat may be generated by a combination of an internal combustion engine (for example, a gas engine) and a power generation device driven by the internal combustion engine, or a combination of an external combustion engine and a power generation device.

It is a figure which shows the structure of the cogeneration system which concerns on embodiment. It is a figure which shows the hardware constitutions of the control means shown in FIG. 1, (a) is related with a main control apparatus, (b) is related with a sub-control apparatus. It is a figure which shows the function structure of the main controller shown in FIG. 1, and a sub controller. It is a figure which shows the function structure of the main controller shown in FIG. 1, and a sub controller. It is a sequence diagram which shows operation | movement of the cogeneration system shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cogeneration system, 10 ... Fuel cell power generation device, 13 ... FC heater (heater), 14 ... Pump, 21 ... Hot water storage tank, 22 ... Temperature sensor (temperature sensor), 23 ... Hot water tank heater (heater), 24 ... Three-way valve for circulation (switching valve), 32 ... circulation pipe (pipe), 32a ... reverse pipe, 32b ... forward pipe, 32c ... bypass, 41 ... pipe temperature sensor (first temperature) Sensor), 42 ... Pipe temperature sensor (second temperature sensor), 152 ... Pipe temperature acquisition part (pipe temperature acquisition means), 153 ... Temperature judgment part (temperature judgment means), 154 ... FC heater control part ( (Heating control means), 155 ... pump control section (circulation control means), 156 ... temperature difference judgment section (circulation control means), 157 ... heating amount judgment section (heating control means), 262 ... temperature acquisition section (temperature acquisition means) 263 ... Hot water tank heater Control unit (heating control means), a three-way valve control unit for 264 ... circulation (flow path control means).

Claims (4)

A power generation device that generates electric power and heat, a hot water storage tank that stores water, and a circulation path are formed between the power generation device and the hot water storage tank, and heat generated in the power generation device is absorbed. A pipe freezing prevention method in a cogeneration system comprising a pipe for sending water into the hot water tank,
A temperature acquisition step of acquiring an environmental temperature by a temperature sensor provided in at least one of the power generator and the hot water storage tank;
A temperature determination step of determining whether or not the environmental temperature acquired in the temperature acquisition step is a predetermined value or less;
A heating control step of heating water in the pipe line by a heater when the environmental temperature is determined to be equal to or lower than a predetermined value in the temperature determination step;
A circulation control step for circulating water in the pipe line by a pump provided in the middle of the pipe line when the environmental temperature is determined to be equal to or lower than a predetermined value in the temperature judging step;
A pipeline temperature acquisition step of acquiring two temperatures of the pipeline by means of first and second temperature sensors provided at different parts of the pipeline,
In the circulation control step, the flow rate of water in the pipeline is controlled so that the difference between the two temperatures acquired in the pipeline temperature acquisition step is a predetermined value or less.
A pipe freezing prevention method characterized by that. The pipe freezing prevention method according to claim 1 , wherein, in the heating control step, a heating amount by the heater is controlled so that the two temperatures are equal to or higher than a predetermined value. A power generation device that generates electric power and heat, a hot water storage tank that stores water, and a circulation path are formed between the power generation device and the hot water storage tank, and heat generated in the power generation device is absorbed. A cogeneration system comprising a conduit for sending water into the hot water tank,
Temperature acquisition means for acquiring an environmental temperature by a temperature sensor provided in at least one of the power generation device and the hot water storage tank;
Temperature determination means for determining whether or not the environmental temperature acquired by the temperature acquisition means is a predetermined value or less;
A heating control means for heating the water in the pipe line by a heater when the temperature judgment means judges that the environmental temperature is not more than a predetermined value;
A circulation control means for circulating water in the pipe line by a pump provided in the middle of the pipe line when the temperature judgment means determines that the environmental temperature is equal to or lower than a predetermined value;
Pipeline temperature acquisition means for acquiring two temperatures of the pipeline by means of first and second temperature sensors provided in different parts of the pipeline,
The circulation control means controls the flow rate of water in the pipe line so that the difference between the two temperatures acquired by the pipe line temperature acquisition means is a predetermined value or less.
Cogeneration system characterized by that. The cogeneration system according to claim 3 , wherein the heating control unit controls a heating amount by the heater so that the two temperatures are equal to or higher than a predetermined value.

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