JP2007132613A - Cogeneration system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cogeneration system which sufficiently cools a cogeneration means even when a control power source is cut off. <P>SOLUTION: The cogeneration system 1 has: a fuel cell 2 generating electric power and heat; a hot water storage tank 6; a heating medium circulation passage circulating a heating medium having absorbed power generation heat of the fuel cell 2 between the hot water storage tank 6 and the fuel cell 2; a bypass passage bypassing the hot water storage tank 6 and returning the heating medium to the fuel cell 2; a hot water storage tank bypass valve 12 and a circulation passage opening and closing valve 13 which carry out changing between a passage sending the heating medium to the hot water storage tank 6, and a passage sending the heating medium to the bypass passage; and a control means. In the hot water storage tank bypass valve 12 and the circulation passage opening and closing valve 13, a passage of the heating medium is mechanically changed to a hot water storage tank 6 side when feeding to the control means is stopped. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cogeneration system that supplies electric power generated by a combined heat and power means such as an engine generator and a fuel cell to a load, and uses heat generated by the operation of the combined heat and power means for hot water supply and heating. .

  In cogeneration systems that use waste heat from cogeneration means that generate heat together with power, such as engine generators and fuel cells, for hot water and heating, adjust the time lag between heat generation and heat demand. For this purpose, a hot water storage tank is generally provided.

Patent Document 1 discloses a heat exchange means for exhaust heat that recovers exhaust heat of a generator and heats a heat medium, a hot water storage tank, and a heat exchange means for heating that heats water in the hot water tank with the heat medium. A heat medium circulation pipe for circulating the heat medium between the heat exchange means for exhaust heat and the heat exchange means for heating, and the heat exchange of the heat medium by bypassing the heat exchange means for heating There is disclosed a cogeneration system including a bypass pipe for returning to the means, a flow path for flowing the heat medium to the heat exchange means for heating, and a switching valve for switching a flow path for flowing the heat medium to the bypass pipe. In this cogeneration system, when the temperature of the heat medium is lower than the temperature of the water in the hot water tank, the heat medium flows through the bypass pipe, so that the heat of the water in the hot water tank is not taken away by the heat medium. Therefore, hot water having a stable temperature can be supplied from the hot water storage tank.
JP-A-11-223385

  The control device of the cogeneration system described in Patent Document 1 is driven by a commercial power source. This is because the control device also controls the start and stop of the generator, and therefore it is necessary to be driven by electric power of a different system from the cogeneration system. Further, once the generator, particularly the fuel cell, is stopped, it takes time to restart and consumes energy, so it is not desirable to frequently start and stop. For this reason, there is a technical request to continue the operation of the generator even if the power source (hereinafter referred to as “control power source”) that drives the control device for some reason goes down temporarily. However, if the control power supply goes down, the flow path cannot be switched. Therefore, if a flow path that bypasses the hot water tank is selected immediately before the control power supply down, the heat medium absorbs the exhaust heat of the generator and becomes hot. Even if it becomes, there is a problem that heat cannot be radiated to the hot water tank. Therefore, the generator cannot be cooled, and the generator may be damaged.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a cogeneration system that can sufficiently cool the combined heat and power means when the control power supply is cut off.

  A first configuration of a cogeneration system according to the present invention includes a thermoelectric supply unit that generates electric power and heat, a heat storage tank that stores heat generated by the cogeneration unit, the heat storage tank, and the cogeneration unit. A heat medium circulation path for circulating the heat medium between, a bypass path for bypassing the heat storage tank and returning the heat medium to the combined heat and power supply means, and a flow path of the heat medium for the heat storage tank In a cogeneration system having a flow path switching means for switching to any one of the bypass paths and a control means for controlling a switching operation of the flow path switching means, the flow path switching means supplies power to the control means. When stopped, the flow path of the heat medium is mechanically switched to the heat storage tank side.

  According to this configuration, since the flow path switching unit causes the heat medium to flow into the heat storage tank when the power source that drives the control unit is interrupted, the heat medium that has absorbed the heat generated by the combined heat and power supply unit is heated to the heat storage tank. , And the heat medium which has lost its heat and becomes low temperature returns to the combined heat and power supply means. Therefore, even when the control power source is down, the cogeneration means can be cooled. Here, the combined heat and power means is a broad concept including not only a generator powered by a heat engine or the like but also an electrochemical power generation means such as a fuel cell. When generating electric power, all the devices that discharge heat as a by-product are included in the cogeneration means here.

  According to a second configuration of the cogeneration system according to the present invention, in the first configuration, the flow path switching unit is a three-way valve disposed at a branch point or a merge point of the heat medium circulation path and the bypass path. It is characterized by being.

  This configuration can also cool the combined heat and power means even if the control power supply goes down. The three-way valve may be of any type as long as the valve body is held at a specific position when not energized, but a solenoid valve is optimal.

  According to a third configuration of the cogeneration system according to the present invention, in the first configuration, the flow path switching unit is an electromagnetic on-off valve provided in a portion parallel to the bypass path of the heat medium circulation path. A bypass path opening / closing valve that is an electromagnetic opening / closing valve provided in the bypass path, and the circulation path opening / closing valve is of a normally open type that opens when not energized.

  According to this configuration, since the circuit opening / closing valve is a normally open type electromagnetic opening / closing valve that opens when not energized, when the control power source is down, the heat medium that absorbs the heat generated by the combined heat and power supply means is installed in the heat storage tank. After passing through and releasing heat, it returns to the combined heat and power supply means. In addition, even during normal operation, it takes a long time to open the circulation path on-off valve and return the heat medium in the heat storage tank to the combined heat and power supply means, so power consumption can be saved by using a normally open type electromagnetic on-off valve. .

  A fourth configuration of the cogeneration system according to the present invention is characterized in that, in the third configuration, the bypass on-off valve is a normally closed type that closes when not energized.

  According to this configuration, since the bypass on / off valve is a normally closed electromagnetic on / off valve that closes when not energized, when the control power is down, the heat medium that has absorbed the heat generated by the combined heat and power supply bypasses the heat storage tank. Without flowing, everything flows into the heat storage tank. Even during normal operation, the bypass on-off valve is closed and the time for allowing the heat medium to flow into the heat storage tank is long, so that the power consumption can be saved by using a normally-closed electromagnetic on-off valve.

  According to a fifth configuration of the cogeneration system of the present invention, in any one of the first to fourth configurations, the heat storage tank includes a heat medium flowing through the heat medium circulation path and a heat medium in the heat storage tank. It is characterized by providing the heat exchanger which performs heat exchange between.

  According to this configuration, since the heat medium circulates in the heat medium circulation path and does not go outside, the heat medium in the heat storage tank can be kept clean.

  In a sixth configuration of the cogeneration system according to the present invention, in any one of the first to fourth configurations, the heating medium is water, and the heat storage tank generates heat generated by the combined heat and power supply means. It is a stratified hot water tank that stores hot water as hot water

  According to this configuration, since the heat exchanger is not interposed between the heat storage tank and the heat medium circulation path, loss due to heat exchange does not occur. This improves the efficiency of the cogeneration system.

  As described above, according to the present invention, even when the control power source is down, the heat medium that has become a high temperature by absorbing the heat generated by the combined heat and flow means flows into the heat storage tank and dissipates the heat to the heat storage tank. Therefore, even if the control power supply is down, the combined heat and power supply means can be sufficiently cooled.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a piping diagram of a cogeneration system 1 according to an embodiment of the present invention. The cogeneration system 1 includes a fuel cell 2, a heat exchanger 3, a heating auxiliary boiler 4, a fan coil unit 5, a hot water tank 6, a radiator 7, and other devices described later. The cogeneration system 1 is controlled by a control computer (not shown).

  The fuel cell 2 is a cogeneration unit that supplies electric power to an electric load (not shown), and includes a cooling pipe (not shown) that absorbs and discharges heat generated as a by-product of electric power in cooling water. Further, the cooling water that has become high temperature by absorbing heat flows out of the cooling pipe and flows into the primary side pipe 3 a of the heat exchanger 3.

  The heat exchanger 3 includes cooling water that flows out from the fuel cell 2 and flows into the primary side pipe line 3a, and heating water that flows out from the fan coil unit 5 and flows into the secondary side pipe line 3b (heating medium for heating). It is an apparatus which heats the heating water by exchanging heat between them.

  The auxiliary heating boiler 4 is an auxiliary heat source device that is operated when the temperature of the heating water flowing out from the secondary side pipe 3b of the heat exchanger 3 is lower than the required temperature of the fan coil unit 5, and heats the heating water. is there.

  The fan coil unit 5 is a heater that discharges heat of high-temperature heating water flowing through the secondary side pipe 3b of the heat exchanger 3 and the auxiliary boiler 4 for heating into the space to be heated. In addition, 8 is a circulation pump which circulates heating water in the heating water circulation path which returns from the secondary side pipe line 3b of the heat exchanger 3 to the secondary side pipe line 3b through the heating auxiliary boiler 4 and the fan coil unit 5. . Reference numeral 9 denotes a heating medium bypass passage opening / closing valve for opening and closing a pipe passage (heating heating medium bypass passage) that bypasses the fan coil unit 5.

  The hot water tank 6 is a container for storing cooling water. The cooling water flowing out of the fuel cell 2 during the operation of the fuel cell 2 is sufficiently hot even if heat is applied to the heating water by the heat exchanger 3, so it is injected from the top of the hot water tank 6 and is not shown if necessary. It is supplied to a hot water supply load (for example, a currant, a shower head, etc.) or a heat load (for example, a heat exchanger for reheating a bathtub). In addition, since the cooling water that has lost its heat and stayed at a low temperature is retained at the bottom of the hot water tank 6, it is extracted and returned to the fuel cell 2. In addition, although a hot water supply pipe is connected to the lower part of the hot water storage tank 6 and a hot water supply pipe is connected to the upper part, illustration is abbreviate | omitted here.

  The radiator 7 is a radiator that cools the cooling water to a predetermined temperature when the temperature of the cooling water returning to the fuel cell 2 exceeds a predetermined temperature (when the cooling water is not sufficiently cooled).

  In this way, the cooling water that has become high temperature by absorbing the generated heat generated in the fuel cell 2 is poured into the top of the hot water tank 6 through the heat exchanger 3 and extracted from the bottom of the hot water tank 6. The low-temperature cooling water is radiated by the radiator 7 as necessary and is returned to the fuel cell 2. Hereinafter, in this specification, a circuit in which the cooling water (heat medium) circulates between the fuel cell 2 (heat and power co-feeding means) and the hot water tank 6 (heat storage tank) will be referred to as a “heat medium circulation path”. In addition, a cooling water circulation pump (not shown) is provided inside the fuel cell 2, and the cooling water that has become a high temperature by absorbing the generated heat is sent to the heat medium circulation path.

  10 is a three-way valve. The three-way valve 10 is a switching valve that selects a flow path 10 a from the primary side pipe 3 a of the heat exchanger 3 to the hot water storage tank 6 and a flow path 10 b from the heat exchanger bypass flow path 11 to the hot water storage tank 6. When the fan coil unit 5 is in operation, the flow path 10 a is selected, and high-temperature cooling water flowing out from the fuel cell 2 is passed through the heat exchanger 3 to supply heat to the fan coil unit 5. When the fan coil unit 5 is stopped, the flow path 10b is selected, and the high-temperature cooling water flowing out from the fuel cell 2 bypasses the heat exchanger 3 and flows directly into the hot water tank 6.

  12 is a hot water tank bypass valve, and 13 is a circulation path opening / closing valve. The hot water tank bypass valve 12 and the circulation path opening / closing valve 13 are provided in the heat medium circulation path so as to bypass the hot water tank 6 and return the cooling water to the fuel cell 2 (hot water tank bypass path) and the cooling water to the hot water tank 6. A flow path switching means is configured to switch the flow path to be poured. That is, when the hot water tank bypass valve 12 is opened and the circulation path opening / closing valve 13 is closed, all the cooling water bypasses the hot water tank 6 and returns to the fuel cell 2, and the hot water tank bypass valve 12 is closed. When the circulation path opening / closing valve 13 is opened, all the cooling water returns to the fuel cell 2 via the hot water tank 6.

  When the temperature of the cooling water passing through the three-way valve 10 is lower than a predetermined temperature (for example, 40 ° C.), the hot water tank bypass valve 12 is opened, the circulation path opening / closing valve 13 is closed, and the cooling water is directly supplied to the radiator 7. Conversely, when the temperature of the cooling water passing through the three-way valve 10 is higher than a predetermined temperature (for example, 45 ° C.), the hot water tank bypass valve 12 is closed, the circulation path on / off valve 13 is opened, and the cooling water is supplied to the hot water tank 6. While pouring, warm water in the lower layer of the hot water tank 6 is caused to flow to the radiator 7. This is to store hot water at a certain temperature or higher in the hot water tank 6. The hot water tank bypass valve 12 and the circulation path opening / closing valve 13 are solenoid valves, the hot water tank bypass valve 12 is a normally closed type that closes when the solenoid is not excited, and the circulation path opening / closing valve 13 is excited by the solenoid. It is a normally open type that opens when it is not. That is, the hot water tank bypass valve 12 is closed when the driving power source is down, and the circulation path opening / closing valve 13 is opened when the driving power source is down.

  Reference numeral 14 denotes a cooling water temperature detector that detects the temperature of the cooling water flowing from the fuel cell 2.

  Since it is configured in this manner, when the control power supply of the cogeneration system 1 goes down due to some trouble, the hot water tank bypass valve 12 is closed and the circulation path on / off valve 13 is opened, so that the control power supply is just before going down. Whatever the state of the hot water tank bypass valve 12 and the circulation path open / close valve 13, the hot cooling water is poured into the top of the hot water tank 6, and the low temperature cooling water is extracted from the bottom of the hot water tank 2. Thus, the fuel cell 2 can be cooled.

  In the present embodiment, as a specific example of the flow path switching means, a combination of the hot water tank bypass valve 12 and the circulation path on / off valve 13 is shown, but instead of the combination of the hot water tank bypass valve 12 and the circulation path on / off valve 13, A three-way valve may be provided at the junction 12a or the junction 12b of the heat medium circulation path and the hot water tank bypass path. In this case, the three-way valve is configured to select a flow path for flowing the cooling water to the hot water tank 6 when the solenoid is not excited.

  In the present embodiment, as a specific example of the heat storage tank, the hot water storage tank 6 that stores the high-temperature cooling water itself that has absorbed the heat generated in the fuel cell 2 is shown. However, the hot water storage tank 6 includes a heat exchanger. Thus, heat exchange is performed between the high-temperature cooling water and the hot water in the hot water storage tank 6 so that the low temperature cooling water is returned to the fuel cell 2 without being poured into the hot water storage tank 6. You may comprise.

It is a piping system diagram of a cogeneration system concerning an example of the present invention.

Explanation of symbols

1 Cogeneration system 2 Fuel cell 3 Heat exchanger 4 Heating auxiliary boiler 5 Fan coil unit 6 Hot water storage tank (heat storage tank)
7 Radiator 8 Circulation pump
9 Heating medium bypass passage opening / closing valve for heating 10 Three-way valve 11 Heat exchange bypass passage 12 Hot water tank bypass valve 13 Circulation passage opening / closing valve 14 Cooling water temperature detector

Claims (6)

A cogeneration means for generating electric power and heat;
A heat storage tank for storing heat generated by the cogeneration means; and
A heat medium circulation path for circulating a heat medium between the heat storage tank and the cogeneration means;
A bypass path for bypassing the heat storage tank and returning the heat medium to the combined heat and power means;
A flow path switching means for switching the flow path of the heat medium to either the heat storage tank or the bypass path;
In a cogeneration system having control means for controlling the switching operation of the flow path switching means,
The cogeneration system, wherein the flow path switching means mechanically switches the flow path of the heat medium to the heat storage tank side when power supply to the control means is stopped. 2. The cogeneration system according to claim 1, wherein the flow path switching unit is a three-way valve disposed at a branch point or a junction point of the heat medium circulation path and the bypass path. The flow path switching means is
A circulation path opening / closing valve, which is an electromagnetic opening / closing valve provided in a portion of the heating medium circulation path parallel to the bypass path;
And a bypass passage opening / closing valve that is an electromagnetic opening / closing valve provided in the bypass passage;
Consisting of
The cogeneration system according to claim 1, wherein the circulation path on-off valve is a normally open type that opens when not energized. The cogeneration system according to claim 3, wherein the bypass on-off valve is a normally closed type that closes when power is not supplied. The said heat storage tank is provided with the heat exchanger which performs heat exchange between the heat medium which flows through the said heat-medium circulation path, and the heat medium in the said heat storage tank, The Claim 1 thru | or 4 characterized by the above-mentioned. Cogeneration system described in 1. The heating medium is water;
The cogeneration system according to any one of claims 1 to 4, wherein the heat storage tank is a stratified hot water storage tank that stores hot heat generated by the combined heat and power supply means as hot water.

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