JP3674790B2 - Cogeneration system - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a cogeneration system (a power generation and hot water supply apparatus) that performs power generation and hot water supply (including supply of other heat medium) using a gas engine or the like that uses city gas as fuel as a prime mover.
[0002]
[Prior art]
Many cogeneration systems that generate electricity and hot water using a gas engine powered by city gas as a prime mover are currently in practical use. In factories, hotels, hospitals, and offices that consume a large amount of heat energy (hot water, steam, etc.) together with electricity, a cogeneration system is installed to obtain electricity and hot water. At this time, about 30% of the energy of the fuel can be converted into electricity, and about 40% can be converted into thermal energy such as hot water or steam. Accordingly, the overall thermal efficiency reaches a very high value of about 70%. The overall power generation efficiency of a general power generation / transmission system is about 35%.
[0003]
As a basic concept in the operation control of this cogeneration system, there are an electric main heat subordinate operation and a heat main subordinate operation. In the former, the operation pattern of the cogeneration system is set according to the electrical load (demand) of all power consuming equipment in the building where the cogeneration system is installed, and the heat output generated by the operation is made as effective as possible. The idea is to use (throw away if not used up). The latter is the opposite idea. In the case of a general building cogeneration system, there are many electric main heat followers. When the thermal load (demand) of a building is larger than the heat output of the cogeneration system, a shortage boiler is used to satisfy the insufficient heat load.
[0004]
[Problems to be solved by the invention]
However, since the electrical load is low, there is a case where there is a margin of electrical output of the cogeneration system (the operation rate of the cogeneration system is low), and the thermal load may be larger than the heat output at that time. In this case, a separate boiler is operated to compensate for the insufficient heat output. However, such boilers may have unexpectedly low thermal efficiency (65% -70%), and the overall thermal efficiency of the cogeneration system may be higher. However, in the case of a conventional cogeneration system, no consideration has been given to equipment that stores excess electric power in place of heat. For this reason, a separate boiler had to be operated despite the low utilization rate of the cogeneration system.
[0005]
An object of the present invention is to provide a cogeneration system that can store surplus power as thermal energy, contributes to overall energy saving, and has improved capability to cope with load fluctuations.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the cogeneration system of the present invention is:
Prime mover,
A generator driven by this prime mover;
A hot water heat exchanger that produces hot water using the exhaust heat of the prime mover (including heat of cooling removal),
A hot water tank for storing hot water,
A hot water heater that electrically heats the hot water in the hot water tank;
Surplus power supply means for supplying surplus power from the generator to the hot water heater;
Equipped with,
The cogeneration system further comprises a water heater that supplies hot water to the hot water storage tank, which is separate from the hot water heat exchanger .
[0007]
[Action]
The cogeneration system of the present invention produces hot water by recovering exhaust gas generated by a prime mover or sensible heat of prime mover cooling water with a hot water heat converter. The produced hot water is stored in a hot water tank. A hot water heater is provided in the hot water tank, and the hot water in the hot water tank can be electrically heated. The remaining surplus power obtained by subtracting the electrical load from the electrical output of the cogeneration system is sent to the hot water heater through the surplus power supply means from the generator, is used for heating the hot water, and is stored in the form of its thermal energy, Or used. Since the electricity-to-heat conversion efficiency of the hot water heater section is almost 100%, it is possible to produce hot water with high heat efficiency comparable to boilers when combined with exhaust heat utilization. Moreover, the effect of improving the power generation efficiency of the generator can be obtained by increasing the operating rate of the cogeneration system.
[0008]
It is desirable that the cogeneration system of the present invention further includes a flow rate control valve for controlling the amount of water supplied to the hot water heat exchanger. The flow rate control valve can be used to control the amount and temperature of hot water on the outlet side of the hot water heat converter (that is, the hot water tank inlet side).
[0009]
Cogeneration system of the present invention is further of another system and the hot water heat exchanger, comprise a water heater for supplying hot water to the hot water storage tank. When the electricity and heat output of the cogeneration system is maximized, hot water can be supplied to the hot water tank in a separate system when there is still not enough heat. This also has the advantage that a hot water pump that sends hot water from the hot water tank to each hot water consuming device can be used effectively.
[0010]
【Example】
Examples of the present invention will be described below.
FIG. 1 is a system diagram of a cogeneration system according to an embodiment of the present invention. The cogeneration system of FIG. 1 includes main equipment such as a gas engine 1, a generator 3, a hot water heat converter 5, a hot water heater 17, a hot water tank 7, and the like.
[0011]
The gas engine 1 (prime mover) is a reciprocating internal combustion engine, and operates upon receiving city gas supply from the city gas line 2. The output shaft of the gas engine 1 is connected to the input shaft of the generator 3, and the generator 3 is driven to generate power. The generated power is sent to the power consuming device 63 through the electric path 62. When the load of the power consuming device 63 exceeds the capacity of the generator 3, commercial power is supplied from the commercial power path 65. Further, when the output of the generator 3 exceeds the load of the power consuming device 63, the surplus power is sent to the hot water heater 11 of the hot water tank 7 through the electric path 13 (surplus power supply means).
[0012]
A cooling water channel 21 is provided in a housing or the like of the gas engine 1, and the gas engine 1 is water-cooled. The cooling water exiting the cooling water channel 21 is heated by the waste gas of the gas engine 1 in the waste gas heat exchanger 25. In addition, the waste gas of the gas engine 1 is sent from the waste gas discharge path 23 to the waste gas heat exchanger 25 and then released. The cooling water exiting the waste gas heat exchanger 25 is sent to the hot water heat exchanger 5 through the high temperature cooling water passage 27.
[0013]
In the hot water heat exchanger 5, the heat of the high-temperature cooling water is used for heating the water coming from the water supply pipe 31 and the heat medium sent to each heat consuming device 47. That is, water supplied from the water supply is supplied from the water supply pipe 31 through the flow rate control valve 15, enters the hot water heat exchanger 5, is heated to about 80 ° C., and is sent to the hot water tank 7 through the hot water pipe 35.
[0014]
The heat medium is sent from the heat consuming device 47 (heating, absorption cooling, etc.) to the hot water heat exchanger 5 by the heat medium pump 43 and heated, and is sent to each heat consuming device 47 through the heat medium pipe 49. . In some cases, the heat medium returning from the heat consuming device 47 is sent from the three-way switching valve 45 to the hot water tank 7 through the heat medium pipe 55, and after being primarily heated in the hot water tank 7, passes through the heat medium pipe 53. Secondary heating is performed by the hot water heat exchanger 5.
[0015]
The hot water tank 7 is provided with a hot water heater 11 for electric heating, which is a feature of the cogeneration system of the present invention. The hot water heater 11 is supplied with surplus power from the generator 3 and heats the hot water in the hot water tank by electrical resistance. That is, the surplus power is converted into thermal energy and stored in the hot water tank 7.
[0016]
As a facility for supplying warm water to the hot water tank 7, a water heater 17 is provided as a facility separate from the warm water pipe 35 from the warm water heat exchanger 5. The water heater 17 heats the water supplied from the water supply pipe 31 using city gas or the like as fuel and sends the water to the hot water tank 7 as hot water. This water heater 17 is used when the output of the gas engine 1 is maximized but the hot water is insufficient, or when the power load is too low to operate the gas engine 1 and the efficiency is low. Producing hot water shortage. The hot water in the hot water tank 7 is sent to the hot water consuming device 61 (bath etc.) by the pump 60 and consumed.
[0017]
【The invention's effect】
As apparent from the above description, the present invention exhibits the following effects.
{Circle around (1)} The cogeneration system of the present invention has a hot water heater that electrically heats the hot water in the hot water tank, so that surplus power generated by the generator can be stored as thermal energy. Therefore, it becomes further energy saving.
[0018]
(2) When surplus power is generated, it can be stored in place of heat energy, and the stored heat energy can be used when the heat load is large, so that it is possible to provide a cogeneration system with improved ability to cope with load fluctuations.
[Brief description of the drawings]
FIG. 1 is a system diagram of a cogeneration system according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Gas engine 2 City gas line 3 Generator 7 Hot water tank 11 Hot water heater 13 Electric circuit 15 Flow control valve 17 Water heater 21 Cooling water flow path 25 Waste gas heat exchanger 45 Three-way valve 47 Heat consumption apparatus 61 Hot water consumption apparatus

Claims (2)

Prime mover,
A generator driven by this prime mover;
A hot water heat exchanger that produces hot water using the exhaust heat of the prime mover (including heat of cooling removal),
A hot water tank for storing hot water,
A hot water heater that electrically heats the hot water in the hot water tank;
Surplus power supply means for supplying surplus power from the generator to the hot water heater;
Equipped with,
The cogeneration system further comprises a water heater that supplies hot water to the hot water storage tank, which is separate from the hot water heat exchanger .   The cogeneration system according to claim 1, further comprising a flow control valve that controls a water supply amount to the hot water heat exchanger.

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