JP2006105452A - Cogeneration system and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cogeneration system having lower manufacturing cost and a smaller installation area. <P>SOLUTION: The cogeneration system comprises a fuel cell 1 having a fuel treatment device 2 for inputting fuel and taking hydrogen, a stack 3 for taking DC power out of hydrogen and oxygen from the fuel treatment device 2, and an inverter 4 for inverting the DC power into AC power, a heat exchanger 5 provided in a pipeline 21 connected to the stack 3, a heat source water pipeline 18 connecting the heat exchanger 5 to an absorption refrigerator 6, a cooling water pipeline 19 connecting the absorption refrigerator 6 to a cooling tower 12, a heat exchanger 14 provided in the cooling water pipeline 19, a pipeline 22 connecting the heat exchanger 14 to the heat source water pipeline 18, a three-way valve 9 provided in the heat source water pipeline 18 and adapted to be controlled corresponding to a heat source water return temperature T1 to supply heat source water from the absorption refrigerator 6 to the heat exchanger 5 and the heat exchanger 14 in a branching manner, and a cold water pipeline 20 connecting the absorption refrigerator 6 to a plurality of fan coil units 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cogeneration system having an absorption refrigerator and a control method thereof.

  FIG. 6 is a diagram showing a conventional cogeneration system. As shown in the figure, a polymer electrolyte fuel cell 1 has a fuel treatment device 2, a stack 3, and an inverter 4. The fuel processing device 2 inputs fuel and takes out hydrogen, and the stack 3 performs fuel processing. DC power is taken out from the hydrogen and oxygen from the device 2, and the inverter 4 converts the DC power into AC power and outputs the AC power to the load. Further, two heat exchangers 5 and 31 are provided in the pipe line 21 connected to the stack 3, and a heat source water pipe line that connects the heat exchanger 5 and the absorption refrigerator 6 that uses the exhaust heat of the fuel cell 1. 18, the heat source water pump 18 is provided in the heat source water pipe 18, the second three-way valve 8 is provided in the heat source water pipe 18, and the opening degree of the three-way valve 8 is the temperature of the heat source water in the heat source water pipe 18. The temperature is controlled according to the temperature measured by the thermometer 10 that measures the heat source water return temperature T1. A cooling water pipe 19 that connects the absorption refrigerator 6 and the cooling tower 12 is provided, and a cooling water pump 13 is provided in the cooling water pipe 19. Further, a chilled water pipe 20 connecting the absorption refrigerator 6 and the plurality of fan coil units 15 is provided, and a chilled water pump 16 is provided in the chilled water pipe 20. Further, the heat source water pipe 18 is provided with a third three-way valve 11, and the opening degree of the three-way valve 11 is the temperature measured by the thermometer 17 for measuring the temperature of the cold water in the cold water pipe 20, that is, the cold water outlet temperature T2. Is controlled accordingly. Further, a cooling water pipe 33 that connects the heat exchanger 31 and the cooling tower 32 is provided.

  In this cogeneration system, the heat generated in the stack 3 is taken out to the absorption refrigerator 6 by the heat exchanger 5 and used for the regeneration of the lithium bromide solution inside the absorption refrigerator 6, and the heat source water at a constant temperature is heated. Returned to the exchanger 5. Further, inside the absorption refrigerator 6, for example, cold water of 7 ° C. is produced by evaporation, and the cold water is sent to the fan coil unit 15 to be used for cooling. Further, when the absorption refrigerator 6 is stopped or when the load of the absorption refrigerator 6 is small, heat is extracted by the heat exchanger 31 and is radiated by the cooling tower 32. The heat generated from the absorption refrigerator 6 is radiated by the cooling tower 12.

JP-A-9-236352

  In the conventional cogeneration system shown in FIG. 6, in addition to the cooling tower 12 for dissipating the exhaust heat of the absorption refrigerator 6, a cooling tower 32 for dissipating the exhaust heat of the fuel cell 1 is required. In addition to requiring equipment costs, the installation area is increased. In addition, when the fuel cell 1 and the absorption refrigerator 6 are operating at the maximum output, the cooling towers 12 and 22 are stopped, and equipment is wasted.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a cogeneration system that can be manufactured at low cost and can be reduced in installation area, and a control method therefor.

  In order to achieve this object, in the present invention, in a cogeneration system having a power generation device, an absorption refrigerator that uses exhaust heat of the power generation device, and a cold water utilization device that uses cold water generated by the absorption refrigerator, The heat dissipation device of the absorption refrigerator is also used as the heat dissipation device of the power generator.

  In this case, a heat exchanger is provided in the cooling water line connecting the absorption chiller and the heat dissipation device, and the heat source water in the heat source water line is connected to the heat source water line connecting the power generation device and the absorption chiller. When the return temperature becomes equal to or higher than the first preset temperature set in advance, the opening degree increases as the heat source water return temperature increases, and a part of the heat source water from the absorption chiller is transferred to the heat exchanger. A first three-way valve to supply may be provided.

  In this case, when the heat source water return temperature falls below the first set temperature in the heat source water pipe, the opening degree increases according to the decrease in the heat source water return temperature, and the heat source water from the power generator A second three-way valve that mixes a part of the heat source water with the heat source water returning to the power generation device may be provided.

  In these cases, when the chilled water outlet temperature in the chilled water pipe connecting the absorption refrigerator and the chilled water utilization device to the heat source water pipe is lower than a preset second set temperature, the chilled water outlet temperature A third three-way valve may be provided that increases the opening according to the decrease and mixes part of the heat source water from the power generation device with the heat source water that returns to the power generation device.

  In such a case, a fuel cell may be used as the power generator.

  Further, in the method for controlling the cogeneration system, the exhaust heat of the power generation device not used in the absorption refrigerator is radiated by the heat dissipation device using the first three-way valve, and the heat source water return temperature is obtained. Is kept constant.

  Moreover, in the method for controlling the cogeneration system, when the heat source water return temperature is equal to or higher than the first set temperature, a part of the heat source water from the absorption refrigerator is caused by the first three-way valve. Is supplied to the heat exchanger to maintain the heat source water return temperature constant.

  Further, a power generator, an absorption refrigerator that uses exhaust heat of the power generator, a heat dissipation device that cools the power generator, a heat radiator that cools the absorption refrigerator, and cold water that uses cold water generated by the absorption refrigerator In a cogeneration system having a utilization device, a cooling tower that cools the absorption chiller and a cooling tower that cools the power generation device are combined.

  In this case, a fuel cell may be used as the power generator.

  In these cases, a first three-way valve may be provided in which the heat source water from the absorption refrigerator is branched and supplied to the power generation device and the heat dissipation device side.

  In the cogeneration system according to the present invention, it is not necessary to provide a heat radiating device for radiating the exhaust heat of the power generation device, so that the manufacturing cost can be reduced and the installation area can be reduced.

  In addition, when the third three-way valve is provided, the cooling water outlet temperature can be raised to the second set temperature when the cold water outlet temperature falls below the second set temperature. Can be adjusted.

  FIG. 1 is a diagram showing a cogeneration system according to the present invention. As shown in the figure, a heat exchanger 14 is provided upstream of the cooling tower 12 in the cooling water pipe 19, a pipe 22 connecting the heat exchanger 14 and the heat source water pipe 18 is provided, and the heat source water pipe 18. The first three-way valve 9 is provided, and the opening degree of the three-way valve 9 is controlled in accordance with the heat source water return temperature T1, and when the three-way valve 9 is open, the three-way valve 9 receives the heat source water from the absorption refrigerator 6. The fuel cell 1 (heat exchanger 5) and the cooling tower 12 side, that is, the heat exchanger 14 are branched and supplied.

  In the cogeneration system shown in FIG. 1, the thermal energy generated in the fuel cell 1 is taken out as heat source water to the absorption refrigerator 6 side and used for regeneration of the lithium bromide solution inside the absorption refrigerator 6. Thereby, for example, a constant low temperature water of 71.1 ° C. is returned to the fuel cell 1 side. Further, inside the absorption refrigerator 1, for example, cold water of 7 ° C. is produced by evaporation, and this cold water is sent to the fan coil unit 15 and used as cooling. Further, when the three-way valve 9 is open, a part of the heat source water from the absorption refrigerator 6 is supplied to the heat exchanger 14, and the heat source water heat is taken out to the cooling water in the pipe line 19 in the heat exchanger 14. The heat of the cooling water is radiated by the cooling tower 12. Thus, the cooling tower 12 of the absorption refrigerator 6 is also used as the cooling tower of the fuel cell 1. That is, the cooling tower that cools the absorption refrigerator 6 and the cooling tower that cools the fuel cell 1 are combined.

  FIG. 2 is a graph showing the relationship between the heat source water return temperature T1 and the opening of the three-way valve 8. As is apparent from this graph, when the heat source water return temperature T1 is a first preset temperature set in advance, for example, 71.1 ° C or higher, the three-way valve 8 is closed and the heat source water return temperature T1 is lower than 71.1 ° C. When the heat source water return temperature T1 decreases, the opening degree of the three-way valve 8 increases. The flow of the heat source water at points A and B in FIG. 2 is indicated by arrows A and B in FIG. Therefore, when the heat source water return temperature T1 falls below 71.1 ° C. due to the operation of the absorption refrigerator 6 or the cooling tower 12, the heat source water from the fuel cell 1 returns to the fuel cell 1 through the bypass. Therefore, the heat source water return temperature T1 can be raised to 71.1 ° C.

  FIG. 3 is a graph showing the relationship between the heat source water return temperature T1 and the opening of the three-way valve 9. As is apparent from this graph, when the heat source water return temperature T1 falls below 71.1 ° C. which is the first set temperature, the three-way valve 9 is closed and the heat source water return temperature T1 becomes 71.1 ° C. or higher. The opening of the three-way valve 9 increases as the heat source water return temperature T1 rises. The flow of the heat source water at points C and D in FIG. 3 is indicated by arrows C and D in FIG. For this reason, when the heat source water return temperature T1 becomes 71.1 ° C. or higher, a part of the heat source water from the absorption refrigerator 6 flows into the heat exchanger 14, and heat is exchanged with the cooling water in the heat exchanger 14. Since the heat is dissipated by the cooling tower 12, the heat source water return temperature T1 can be lowered to 71.1 ° C.

  FIG. 4 is a graph showing the relationship between the cold water outlet temperature T2 and the opening degree of the three-way valve 11. As is apparent from this graph, when the chilled water outlet temperature T2 is a second preset temperature set in advance, for example, 7 ° C. or higher, the three-way valve 11 is closed, and when the chilled water outlet temperature T2 falls below 7 ° C., the chilled water outlet The opening degree of the three-way valve 11 increases as the temperature T2 decreases. The flow of the heat source water at points E and F in FIG. 4 is indicated by arrows E and F in FIG. For this reason, when the cold water outlet temperature T2 is 7 ° C. or higher, the heat source water from the fuel cell 1 flows into the absorption refrigerator 6 without flowing to the three-way valve 11 side, but when the cold water outlet temperature T2 falls below 7 ° C. Since a part of the heat source water from the fuel cell 1 flows to the three-way valve 11 side through the bypass and is mixed with the heat source water returning to the fuel cell 1, the cooling load of the fan coil unit 15 is reduced, and the cold water outlet temperature T2 is When the temperature falls below 7 ° C., the cooling capacity of the absorption refrigerator 6 can be suppressed and the cold water outlet temperature T2 can be raised to 7 ° C.

  Thus, in the control method of the cogeneration system according to the present invention, the three-way valves 8 and 9 are controlled by the heat source water return temperature T1, and the three-way valve 11 is controlled by the supply cold water temperature T2, thereby the heat source water return temperature. T1 is maintained at 71.1 ° C. That is, the exhaust heat of the fuel cell 1 that is not used in the absorption refrigerator 6 is radiated by the cooling tower 12 using the three-way valve 9, and the heat source water return temperature T1 is kept constant.

  In such a cogeneration system, since the cooling tower 12 for radiating the exhaust heat of the absorption refrigerator 6 and the cooling tower for radiating the exhaust heat of the fuel cell 1 are combined, Since there is no need to provide a separate cooling tower for radiating heat, the manufacturing cost can be reduced and the installation area can be reduced. Further, when the heat source water return temperature T1 is lower than 71.1 ° C., the heat source water return temperature T1 can be increased to 71.1 ° C., and the heat source water return temperature T1 is 71.1 ° C. or higher. Sometimes, the heat source water return temperature T1 can be lowered to 71.1 ° C., so that the heat source water return temperature T1 can be maintained at 71.1 ° C. Moreover, since the cold water exit temperature T2 can be raised to 7 degreeC when the cold water exit temperature T2 falls from 7 degreeC, the cooling capacity of the absorption refrigerator 6 can be adjusted.

  In the above-described embodiment, the case where the power generation device is the fuel cell 1 has been described. However, the present invention can also be applied to a case where the power generation device is another power generation device. In the above-described embodiment, the case where the heat dissipation device is the cooling tower 12 has been described. However, the present invention can also be applied to the case where the heat dissipation device is another heat dissipation device. Moreover, in the said embodiment, although the case where the cold water utilization apparatus using the cold water produced | generated with an absorption refrigerator was the several fan coil unit 15 was demonstrated, when the said cold water utilization apparatus is another cold water utilization apparatus The present invention can also be applied.

It is a figure which shows the cogeneration system which concerns on this invention. It is a graph which shows the relationship between the heat source water return temperature T1 and the opening degree of the three-way valve 8. It is a graph which shows the relationship between the heat source water return temperature T1 and the opening degree of the three-way valve 9. It is a graph which shows the relationship between the cold water exit temperature T2 and the opening degree of the three-way valve 11. It is an enlarged view which shows a part of cogeneration system shown in FIG. It is a figure which shows the conventional cogeneration system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell 6 ... Absorption refrigerator 8 ... Second three-way valve 9 ... First three-way valve 11 ... Third three-way valve 12 ... Cooling tower 14 ... Heat exchanger 15 ... Fan coil unit 18 ... Heat source water line 19 ... Cooling water pipe 20 ... Cooling water pipe

Claims (10)

  In a cogeneration system having a power generation device, an absorption refrigerator that uses exhaust heat of the power generation device, and a cold water utilization device that uses cold water generated by the absorption refrigerator, the heat dissipation device of the absorption refrigerator is connected to the power generation device. A cogeneration system that is also used as a heat dissipation device.   A heat exchanger is provided in a cooling water line connecting the absorption refrigerator and the heat radiating device, and a heat source water return temperature in the heat source water pipe is in a heat source water line connecting the power generation device and the absorption refrigerator. When the temperature becomes equal to or higher than a first preset temperature set in advance, the opening degree increases in accordance with the rise in the heat source water return temperature, and a part of the heat source water from the absorption chiller is supplied to the heat exchanger. The cogeneration system according to claim 1, wherein one three-way valve is provided.   When the heat source water return temperature falls below the first set temperature in the heat source water pipe, the opening increases in accordance with the decrease in the heat source water return temperature, and a part of the heat source water from the power generator The cogeneration system according to claim 2, further comprising a second three-way valve that mixes the heat source water returning to the power generator with the heat source water.   When the chilled water outlet temperature in the chilled water pipe connecting the absorption chiller and the chilled water utilization device to the heat source water pipe is lower than a preset second set temperature, the cold water outlet temperature is reduced. 4. The core according to claim 2, further comprising a third three-way valve for increasing a degree of opening and mixing a part of the heat source water from the power generation device with the heat source water returning to the power generation device. Generation system.   5. The cogeneration system according to claim 1, wherein a fuel cell is used as the power generation device.   The method for controlling a cogeneration system according to claim 1, wherein the heat generated by the power generation device that has not been used in the absorption chiller is radiated by the heat radiating device using a first three-way valve. A control method for a cogeneration system, characterized in that the return temperature is kept constant.   The method for controlling a cogeneration system according to any one of claims 2 to 4, wherein when the heat source water return temperature is equal to or higher than the first set temperature, the absorption chiller is operated by the first three-way valve. A control method for a cogeneration system, wherein a part of the heat source water from the water source is supplied to the heat exchanger, and the heat source water return temperature is kept constant.   Power generation device, absorption refrigerator that uses exhaust heat of power generation device, heat dissipation device that cools power generation device, heat dissipation device that cools absorption refrigerator, and cold water utilization device that uses cold water generated by absorption refrigerator A cogeneration system comprising: a cooling tower that cools the absorption refrigerator and a cooling tower that cools the power generator.   The cogeneration system according to claim 8, wherein a fuel cell is used as the power generation device.   The cogeneration system according to claim 8 or 9, further comprising a first three-way valve for supplying heat source water from the absorption chiller in a branched manner to the power generation device and the heat dissipation device.

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