JP2003056910A - Heat recovery apparatus and cogeneration system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the total heat efficiency without dissipating useless heat. SOLUTION: Waste heat from a gas engine 1 is recovered in a first heat exchanger 5, and when there is no need of supplying it to a heating load 2, a hot medium from the gas engine 1 is bypassed from the first heat exchanger 5 through a first bypass piping 7 to eliminate useless heat dissipation in the first heat exchanger 5. Further, a flow rate of the hot medium flowing through a second heat exchanger 12 is controlled to be mixed with a hot medium flowing through a second bypass piping 14, whereby return temperature of the hot medium to the gas engine 1 is lowered for prevention of supercooling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat recovery device for recovering heat generated by a heat source and a cogeneration system including the heat recovery device.

[0002]

2. Description of the Related Art As a conventional heat recovery device, for example, a heat medium heated by exhaust heat from a heat source such as a gas engine having a power generation function is circulated in a circulation circuit provided with a heat exchanger. There is a system in which exhaust heat of a heat source is supplied to a load such as a heating terminal via the heat exchanger.

[0003]

In such a conventional example, in the case where exhaust heat is recovered and supplied to a plurality of loads such as a heating terminal and a hot water tank, a circulation circuit in which a heat medium circulates. In this case, heat exchangers for heating terminals and hot water storage tanks will be provided.For example, even when heat supply to the heating terminals is not necessary, the heat medium circulates in the circulation circuit, so As a result of unnecessary heat dissipation in the exchanger, there is a drawback that the total thermal efficiency is lowered.

The present invention has been made in view of the above points, and it is an object of the present invention to improve the total thermal efficiency by eliminating unnecessary heat radiation.

[0005]

In order to achieve the above-mentioned object, the present invention is constructed as follows.

That is, the heat recovery device according to the first aspect of the present invention uses the heat medium heated by the heat generated by the heat source,
In a heat recovery device that circulates a first circulation path provided with a heat exchanger to recover the heat from the heat source by the heat exchanger and supply it to a load, the heat medium is the heat exchanger. A second circulation path that circulates without passing through is provided, and switching means that switches the circulation path of the heat medium to the first circulation path or the second circulation path is provided, and the heat from the heat source is When it is not supplied to the load, it is switched to the second circulation path.

According to the first aspect of the present invention, the heat medium heated by the heat generated by the heat source is circulated in the first circulation path provided with the heat exchanger, so that the heat from the heat source is absorbed. While the heat can be recovered by the heat exchanger and supplied to the load, when the heat from the heat source is not supplied to the load, it is switched to the second circulation path that circulates without passing through the heat exchanger. Unnecessary heat dissipation can be eliminated.

According to a second aspect of the present invention, in the first aspect of the invention, the second circulation path has a common path with the first circulation path, and the heat of the first circulation path is the same. The switching means has a bypass path that bypasses the heat exchanger, and the switching means can switch the circulation path of the heat medium to the bypass path by shutting off the heat medium flowing through the heat exchanger. It is possible to mix the heat medium flowing through the bypass path by adjusting the flow rate of the medium, and when the heat from the heat source is supplied to the load, the return temperature of the heat medium to the heat source becomes a predetermined temperature or higher. like,
The heat medium flowing through the heat exchanger and the heat medium flowing through the bypass path are mixed.

According to the second aspect of the present invention, when the heat from the heat source is recovered by the heat exchanger and supplied to the load, the flow rate of the heat medium flowing through the heat exchanger is controlled to flow through the bypass path. Since the return temperature of the heat medium to the heat source is not too low by mixing with the heat medium, it is possible to prevent overcooling of the gas engine or the like as the heat source.

According to a third aspect of the present invention, in the invention of the first or second aspect, the heat exchanger in the first circulation path is a first heat exchanger, and the second circulation path is A second heat exchanger arranged in the heat storage tank is provided, and when the heat from the heat source is not supplied to the load, the heat from the heat source is radiated by the second heat exchanger and the heat storage tank is provided. To store heat.

According to the third aspect of the present invention, when the heat from the heat source is not supplied to the load, the heat from the heat source can be radiated by the second heat exchanger and stored in the heat storage tank.

According to a fourth aspect of the present invention, in the invention of the third aspect, a second bypass route that bypasses the second heat exchanger is provided in the second circulation route, and the second circulation route is provided. Flow rate adjusting means for adjusting the flow rate of the heat medium flowing through the second heat exchanger and mixing with the heat medium flowing through the second bypass path is provided, and the flow rate is adjusted when the heat from the heat source is not supplied to the load. By the adjusting means, the return temperature of the heat medium to the heat source is equal to or higher than a predetermined temperature,
The heat medium flowing through the second heat exchanger and the heat medium flowing through the second bypass path are mixed.

According to the present invention of claim 4, when the heat from the heat source is recovered by the second heat exchanger and stored in the heat storage tank, the flow rate of the heat medium flowing through the second heat exchanger is adjusted. Since it is controlled and mixed with the heat medium flowing through the second bypass path so that the return temperature of the heat medium to the heat source does not become too low, overcooling of the gas engine or the like as the heat source can be prevented.

A cogeneration system of the present invention according to claim 5 comprises the heat recovery device according to any one of claims 1 to 4, wherein the heat generated by the heat source is the heat generated by the engine.

According to the fifth aspect of the present invention, the power of the engine can be used to generate electric power and the like, while the heat generated by the engine can be recovered and used, thereby improving the energy use efficiency. it can.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The details of the present invention will be described below with reference to the embodiments shown in the drawings.

(Embodiment 1) FIG. 1 is a schematic configuration diagram of a gas engine cogeneration system including a heat recovery device according to one embodiment of the present invention.

In the figure, reference numeral 1 is a gas engine having a power generation function as a heat source, and the electricity generated by this gas engine 1 is supplied to the domestic load of a general household in which the system is installed.

The system of this embodiment recovers exhaust heat from the gas engine 1 by circulating a heat medium such as water cooling of the gas engine and an antifreeze liquid heated by the exhaust gas of the gas engine. The heating engine 2 is supplied to the heating load 2 and the like, and is provided with a forward pipe 3 for sending the heat medium from the gas engine 1 to the outside and a return pipe 4 for returning the heat medium to the gas engine 1.

The outgoing pipe 3 bypasses the first heat exchanger 5 and the heating pipe 6 in which the first heat exchanger 5 for recovering the heat of the heat medium and supplying it to the heating load 2 is provided. After being branched to the first bypass pipe 7, the first mixing valve 8 as a switching means for switching the circulation route of the heat medium as described later.
Are connected via.

A first thermistor 10 for detecting the temperature of the heat medium is provided in the pipe 9 on the downstream side of the first mixing valve 8.
The pipe 9 is provided with a hot water storage pipe 13 provided with a second heat exchanger 12 installed in the hot water storage tank 11.
And a second bypass pipe 14 that bypasses the second heat exchanger 12, and is then connected via a second mixing valve 15.

A pipe 16 downstream of the second mixing valve 15
Includes a second thermistor 1 for detecting the temperature of the heat medium.
7 is provided. An expansion tank 18 and a circulation pump 19 are provided downstream of the pipe 16 so that the return pipe 4
Leading to.

The first heat exchanger 5 communicates with a circulation heating circuit 20 in which hot water for heating that exchanges heat with the heat medium from the gas engine 1 circulates.
The heating heat exchanger (not shown), the heating pump, and the above-mentioned heating load 2 in the auxiliary heat source device 21 are connected.

Further, in this embodiment, a third thermistor 22 for detecting the temperature of the hot water for heating is provided on the downstream side of the first heat exchanger 5 of the circulation heating circuit 20. . The circulation heating circuit 20 is connected to a bath pipe 25 provided with a bath heat exchanger 24 that supplies heat to a bath load 23.
A path of B → three-way valve 26 → A in FIG. 1 is configured so that the heating hot water flow path can be switched to the bath pipe 25 side.

Further, the three-way valve 26 is not a simple pipe path switching valve, but controls the opening ratio of this path when the three-way valve 26 is operated to form the path A → three-way valve 26 → C in FIG. By doing so, the heat medium flow rate ratio between the circulation heating circuit 20 and the path of A → three-way valve 26 → C is adjusted, and as a result, the heat exchange of the first heat exchanger 5 located in the middle of the circulation heating circuit 20. The amount can be changed.

Further, when the heat medium is circulated to the first heat exchanger 5 through the circulation heating circuit 20 when the gas engine 1 is stopped, it does not receive heat but radiates heat in reverse. -> Three-way valve 26-> C is configured so as to bypass it, thereby eliminating wasteful heat dissipation.

An opening / closing valve (not shown) is provided on the heating load side. When the heating load is not used, the opening / closing valve is closed to prevent the flow of hot water to the heating load side. Has been done.

A water supply pipe 27 is connected to the lower water supply port of the hot water storage tank 11 in which the second heat exchanger 12 is installed, while a hot water discharge pipe 28 is connected to the upper water supply port. The hot water mixing valve 29 mixes the hot water from the hot water storage tank 11 with the hot water supplied from the hot water supply pipe 27, and the auxiliary heat source device 21
The hot water is supplied from the hot water supply heat exchanger (not shown).

The auxiliary heat source 21 includes the thermistor 1 described above.
The driving stop of the gas engine 1 is controlled according to the outputs of various sensors such as 0, 17, 22 and the setting operation from the remote control for remotely controlling the auxiliary heat source device 21, and the above-mentioned mixing valves 8, 9 etc. A controller 30 for controlling each unit including is connected.

In this system, when the gas engine 1 and the circulation pump 19 are driven, and there is a heating request, the first mixing valve 8 is used to provide the heating for which the first heat exchanger 5 is provided. The pipe 6 side is fully opened and the first
The bypass pipe 7 side is completely closed, while the second mixing valve 15 is closed.
The hot water storage pipe 1 in which the second bypass pipe 14 side is fully opened and the second heat exchanger 12 is provided.
Fully close the 3rd side.

As a result, the heat medium heated by the exhaust heat of the gas engine 1 at, for example, 75 ° C., as shown in FIG. 2, the outflow pipe 3, the first heat exchanger 5, the first mixture. It circulates in the first circulation path of returning to the gas engine 1 via the valve 8, the second bypass pipe 14, the second mixing valve 15, the expansion tank 18, the circulation pump 19 and the return pipe 4.

On the other hand, the heating pump in the auxiliary heat source device 21 is driven to circulate the hot water for heating in the path of the heating load 2, the first heat exchanger 5 and the auxiliary heat source device 21, and the gas engine 1
The heating medium is heated by the heat medium heated by the exhaust heat of 1, and the heating water is heated by the first heat exchanger 5 and is circulated to the heating load 2 for heating operation.

Further, in this embodiment, as described above, the first mixing valve 8 is not simply fully opened and fully closed.
The controller 30 in the auxiliary heat source device 21 controls the first mixing valve 8 to adjust the flow rate of the heat medium flowing through the first heat exchanger 5 based on the temperature detected by the first thermistor 10 to adjust the flow rate of the heat medium. The temperature of the heat medium mixed with the heat medium flowing through the bypass passage 1 of No. 1 and returned to the gas engine 1 is controlled to be a predetermined temperature, for example, 65 ° C. or higher. As a result, the temperature of the heat medium returning to the gas engine 1 becomes too low, and the gas engine 1
Can be prevented from being overcooled. That is, it is possible to prevent the disadvantage that the temperature of the heat medium for cooling the gas engine 1 is lowered and the dew condensation is generated in the gas engine body to deteriorate the lubricating oil performance.

As another embodiment of the present invention, when there is no risk of supercooling of the heat source, only the first heat exchanger 5 is supplied without flowing the heat medium through the first bypass pipe 7. A heat medium may be passed through.

In this heating operation, in the heat exchange with the heat medium from the gas engine 1, when the heating hot water does not reach the predetermined temperature, that is, the temperature detected by the third thermistor 22 reaches the predetermined temperature. If not, the heating heat exchanger inside the auxiliary heat source device 21 is also used to heat the hot water for heating.

Next, the gas engine 1 and the circulation pump 1
When 9 is driven, the exhaust heat of the gas engine 1
When the heating load 2 is not supplied, the heating pipe 6 provided with the first heat exchanger 5 is provided by the first mixing valve 8.
Side is fully closed and the first bypass pipe 7 side is fully opened, while the second bypass pipe 14 side is fully closed by the second mixing valve 15 and the second heat exchanger 12 is provided. Fully open the hot water storage pipe 13 side.

As a result, the heat medium heated by the exhaust heat of the gas engine 1, as shown in FIG.
First bypass circuit 7, first mixing valve 8, hot water storage pipe 1
3, the second heat exchanger 12, the hot water storage pipe 13, the second mixing valve 15, the expansion tank 18, the circulation pump 19 and the return pipe 4 and circulates in the second circulation path that returns to the gas engine 1. .

By this circulation, the exhaust heat recovered from the gas engine 1 is radiated by the second heat exchanger 12 to heat the low temperature water in the hot water storage tank 11 to store the heat therein. The hot water that has been stored can be used as tap water piping 2 if necessary.
8 is supplied to the auxiliary heat source device 21 via the hot water supply mixing valve 29 and discharged from the hot water supply pipe 21, and is supplied from the water supply pipe 27 to the hot water storage tank 11
Will be supplied with water.

Conventionally, the heat medium from the gas engine 1 flows through the first heat exchanger 5 and radiates unnecessary heat even when it is not used for heating, whereas in this embodiment, Since the heat medium from the gas engine 1 bypasses the first heat exchanger 5 by the first bypass pipe 7,
Unnecessary heat dissipation by the heat exchanger 5 is eliminated, and the total thermal efficiency is improved.

In this embodiment, the controller 30 connected to the auxiliary heat source device 21 while storing heat in the hot water storage tank 11 is based on the temperature detected by the second thermistor 17.
The temperature of the heat medium that returns to the gas engine 1 by controlling the second mixing valve 15 and adjusting the flow rate of the heat medium that flows through the second heat exchanger 12 to mix with the heat medium that flows through the second bypass path 14. Is controlled to be equal to or higher than a predetermined temperature. by this,
It is possible to prevent the temperature of the heat medium returning to the gas engine 1 from becoming too low and the gas engine 1 from being overcooled.

As another embodiment of the present invention, when there is no fear of supercooling of the heat source, the heat medium is not passed through the second bypass pipe 14 and only the second heat exchanger 12 is heated. You may flow a medium.

Further, as another embodiment of the present invention, if the circulation flow rate is made variable by adding a pump whose rotation speed is variable to the circulation pump 19 or by separately adding a flow rate adjusting valve, the unit time per unit time is changed. The amount of heat transfer itself can be made variable, and more detailed and wide-ranging control is possible.

When exhaust heat is supplied to the bath load 23, the heat medium from the gas engine 1 is circulated as in the heating operation as shown in FIG. 4, while the first heat exchanger is used. The hot water flow for heating to be heated by
6, the auxiliary heat source 21, the bath heat exchanger 24, the three-way valve 26, the first heat exchanger 5 and the auxiliary heat source 21 are circulated.

(Other Embodiments) Although the exhaust heat of the gas engine is recovered in the above-described embodiment, as another embodiment of the present invention, the exhaust heat of another generator such as a fuel cell is collected. You may make it collect, and not limited to exhaust heat,
The heat of the boiler or other heat source may be recovered.

[0045]

As described above, according to the present invention, the heat medium heated by the heat generated by the heat source is circulated in the first circulation path provided with the heat exchanger, so that the heat from the heat source is generated. While the heat can be recovered by the heat exchanger and supplied to the load, when the heat from the heat source is not supplied to the load, it is switched to the second circulation path that circulates without passing through the heat exchanger. It is possible to eliminate unnecessary heat radiation and improve the total thermal efficiency.

Further, according to the present invention, the flow rate of the heat medium flowing through the heat exchanger is controlled and mixed with the heat medium flowing through the bypass path so that the return temperature of the heat medium to the heat source does not become too low. Therefore, it is possible to effectively prevent supercooling of a gas engine or the like as a heat source.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a gas engine cogeneration system including a heat recovery device according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing heating operation.

FIG. 3 is a schematic configuration diagram showing a hot water storage operation.

FIG. 4 is a schematic configuration diagram showing a bath operation.

[Explanation of symbols]

1 gas engine 2 heating load 5,12 first and second heat exchangers 7,14 first and second bypass pipes 8,15 first and second mixing valves 6,6 ₁ auxiliary heat source device 11 hot water storage tank

   ─────────────────────────────────────────────────── ─── Continued front page    (71) Applicant 000221834             Toho Gas Co., Ltd.             19-18 Sakurada-cho, Atsuta-ku, Nagoya-shi, Aichi (71) Applicant 000196680             Seibu Gas Co., Ltd.             1-1-17 Chiyo, Hakata-ku, Fukuoka City, Fukuoka Prefecture (72) Inventor Tatsuro Arai             93 Edo-cho, Chuo-ku, Kobe-shi, Hyogo Stock Association             Company Noritsu (72) Inventor Takuji Saeki             93 Edo-cho, Chuo-ku, Kobe-shi, Hyogo Stock Association             Company Noritsu (72) Inventor Takehiro Shimizu             93 Edo-cho, Chuo-ku, Kobe-shi, Hyogo Stock Association             Company Noritsu (72) Inventor, T. Suzuki             1-5-20 Kaigan, Minato-ku, Tokyo Tokyo Gas             Within the corporation (72) Inventor Kenichi Tanogami             1-5-20 Kaigan, Minato-ku, Tokyo Tokyo Gas             Within the corporation (72) Inventor Kazuya Yamaguchi             1-5-20 Kaigan, Minato-ku, Tokyo Tokyo Gas             Within the corporation (72) Inventor Yoshitaka Kasahara             4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Within Osaka Gas Co., Ltd. (72) Inventor Shin Iwata             4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Within Osaka Gas Co., Ltd. (72) Inventor Keiji Takimoto             4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Within Osaka Gas Co., Ltd. (72) Inventor Tadao Sugawara             4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Within Osaka Gas Co., Ltd. (72) Inventor Hiroshi Takagi             Aichi Prefecture Nagoya City Atsuta Ward Sakuradacho 19-18 East             Within Japan Gas Co., Ltd. (72) Inventor Kazuhiro Matsumoto             1-17-21 Chiyo 1-chome, Hakata-ku, Fukuoka City, Fukuoka Prefecture             Inside Seibu Gas Co., Ltd.

Claims (5)

[Claims] 1. A heat medium heated by heat generated by a heat source is circulated through a first circulation path provided with a heat exchanger, whereby heat from the heat source is recovered by the heat exchanger. In a heat recovery device that supplies a load, a second circulation path that circulates the heat medium without passing through the heat exchanger is provided, and the circulation path of the heat medium is the first circulation path or the first circulation path. A heat recovery device comprising switching means for switching to a second circulation path, and switching to the second circulation path when heat from the heat source is not supplied to the load. 2. The heat recovery device according to claim 1, wherein the second circulation path has a common path with the first circulation path, and bypasses the heat exchanger of the first circulation path. The switching means can switch the circulation path of the heat medium to the bypass path by blocking the heat medium flowing through the heat exchanger, while changing the flow rate of the heat medium flowing through the heat exchanger. It can be adjusted and mixed with a heat medium flowing through the bypass path, and when the heat from the heat source is supplied to the load, the return temperature of the heat medium to the heat source is equal to or higher than a predetermined temperature. A heat recovery device characterized by mixing a heat medium flowing through a heat exchanger with a heat medium flowing through the bypass path. 3. The heat recovery device according to claim 1, wherein the heat exchanger in the first circulation path is a first heat exchanger, and the second circulation path is in a heat storage tank. A second heat exchanger arranged is provided, and when heat from the heat source is not supplied to the load, heat from the heat source is radiated by the second heat exchanger and stored in the heat storage tank. A heat recovery device. 4. The heat recovery device according to claim 3, wherein the second circulation path is provided with a second bypass path that bypasses the second heat exchanger, and the second heat exchange apparatus. By adjusting the flow rate of the heat medium flowing through the vessel, the second
Flow rate adjusting means for mixing with the heat medium flowing through the bypass path is provided, and when the heat from the heat source is not supplied to the load, the return temperature of the heat medium to the heat source is not less than a predetermined temperature by the flow rate adjusting means So that the heat medium flowing through the second heat exchanger and the heat medium flowing through the second bypass path are mixed. 5. A cogeneration system comprising the heat recovery device according to claim 1, wherein the heat generated by the heat source is heat generated by an engine.