JPH0828955A - Cogeneration system - Google Patents

Abstract

PURPOSE:To improve an exhaust heat-recovering efficiency and to improve handling convenience. CONSTITUTION:Only an exhaust heat recovering heat exchanger 4 is assembled within a hot water storage tank 3 to increase a temperature difference between exhaust heat from a cogeneration side and a storage hot water temperature. Thus, its exhaust heat recovering efficiency is improved. Further, a water heater 15 is mounted at a hot water supply line 9 to a hot water supply cock 10, and driven only when the hot water demand set water temperature is lower than the storage hot water temperature to supply hot water heated to the desired hot water temperature. When the storage hot water temperature is the same as or higher than the desired water temperature, the hot water in the tank 3 is supplied directly to the cock 10 via a bypass line 17, and the a return line 11 is not returned to the tank 3, but returned to the heater 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention drives an electric generator in an internal combustion engine including a gas engine to generate electricity and
The present invention relates to a so-called cogeneration system in which high-temperature heat energy of cooling water and exhaust gas of an internal combustion engine is recovered and used for heating and hot water supply.

[0002]

2. Description of the Related Art The structure of a conventional cogeneration system will be described with reference to FIG. In FIG. 2, reference numeral 1 is a power generation system that drives a generator by a gas engine to generate power, 2 is cooling water of the gas engine, exhaust heat recovery line that recovers exhaust gas heat, and 3 is a hot water tank. The exhaust heat recovery line 2 is circulated through the exhaust heat recovery heat exchanger 4 incorporated in the hot water storage tank 3 so that the hot water storage tank 3
It is a structure that gives waste heat to the water inside. 5 is an auxiliary heating boiler, and this auxiliary heating boiler 5 is a hot water storage tank 3
If the water temperature inside is below the set value of about 70 ° C, 70 ° C
As described above, the water temperature in the hot water storage tank 3 is detected and driven by the water temperature sensor 6, and the auxiliary heat exchanger 7 raises the water temperature in the hot water storage tank 3. Reference numeral 8 is a water supply line for supplying water into the hot water storage tank 3. 9 is hot water storage tank 3 to hot water tap 1
A hot water supply line for supplying hot water to 0 ... 11 is a return line connected to the terminal 9a of the hot water supply line 9, and hot water in the hot water storage tank 3 is circulated by the heat retention operation pump 12 via the return line 11. By doing so, instant hot water supply is realized. In the figure, 13 is a cooling line, and 14 is a cooling tower. The above-mentioned conventional gas cogeneration system is particularly popular in recent years as an energy saving system because it can use energy with a high efficiency of 70 to 80%.

[0003]

However, the conventional example using the auxiliary heating boiler has the following drawbacks. a. The demand for power generation is relatively stable, but the demand for hot water supply is volatile. For example, when there is a large demand for hot water supply temporarily, the temperature of the hot water storage tank 3 drops sharply and the boiler 5 for auxiliary heating starts driving, but when there is a demand for hot water supply before the temperature is raised to 70 ° C, The desired temperature of hot water cannot be obtained. b. In order to realize stable hot water supply and warming operation at all times, the auxiliary heating boiler 5 keeps the water temperature in the hot water storage tank 3 at about 7
Secured at 0 ° C. Therefore, the heat exchanger 4 for exhaust heat recovery
When recovering the exhaust heat, the exhaust heat recovery efficiency is poor because there is no temperature difference of about 20 ° C. between the exhaust heat temperature of about 90 ° C. and about 70 ° C. Further, when the water temperature in the hot water storage tank 3 is 80 ° C. or higher, the exhaust heat does not go to the hot water storage tank 3 side but to the cooling tower 14 side, where it is abandoned to the atmosphere. Therefore, in many cases, exhaust heat cannot be effectively recovered. c. Since the capacity of the hot water storage tank 3 is large, natural heat dissipation loss is large. d. Since the auxiliary heating boiler 5 raises the entire amount of water in the hot water storage tank 3, the consumption of the auxiliary heating fuel is large. e. Since the hot water in the hot water storage tank 3 is directly supplied to the hot water tap 10, it is impossible to obtain high-temperature water having a hot water storage temperature of about 70 ° C. or higher. It is an object of the present invention to improve exhaust heat recovery efficiency and usability in a cogeneration system.

[0004]

The structure of the cogeneration system according to the present invention is as follows. 1. Hot water storage means incorporating a heat exchanger for recovering exhaust heat, a water supply line connected to the hot water storage means, a hot water supply line for supplying hot water stored in the hot water storage means to a hot water tap, and hot water supply from the hot water supply line to the hot water tap The temperature raising means attached to the hot water supply line for heating the hot water to be heated, the temperature of the hot water supplied to the hot water tap from the hot water supply line is detected by the water temperature sensor, and if the detected temperature is equal to or lower than the set value, the rising temperature is raised. Hot water supply temperature control means for driving the temperature means to raise the water temperature to a set temperature, a bypass line for bypassing the temperature raising means in the hot water supply line, and when the hot water supply water temperature is equal to or higher than a set value, the bypass A direct hot water supply means that opens the line, a terminal of the hot water supply line and the inlet side of the temperature raising means are connected by a return line, and a warming operation pump attached to this return line is installed. Maintenance operation means that a full-time maintenance operation by moving cogeneration system consisting of. 2. 2. The cogeneration system according to claim 1, wherein a gas water heater that starts driving when the water pressure on the hot water supply side drops below a certain value is used as the temperature raising means. 3. The temperature raising means is the cogeneration system according to the above 1 or 2, wherein the temperature raising temperature can be freely set. 4. 1 or 3 wherein a hot water storage tank is provided with a plurality of hot water supply lines and return lines each having a temperature raising means and a warming operation means
The described cogeneration system.

[0005]

[Function] The hot water storage means is automatically supplied with the amount of water commensurate with the discharge of hot water through the water supply line. The exhaust heat of the internal combustion engine that drives the generator enters the exhaust heat recovery exchanger in the hot water storage means via the exhaust heat recovery line, where it gives heat to the water in the hot water storage means and returns to the internal combustion engine. Return. By this action, the exhaust heat is recovered by the water stored in the hot water storage means. As a result, the temperature of the water in the hot water storage means rises. If there is a demand for hot water supply, and the hot water supply demand set water temperature is higher than the water temperature in the hot water storage means, the temperature raising means is driven to heat the hot water flowing in the hot water supply line until the hot water supply demand set water temperature is reached. Supply hot water.

On the other hand, when the water temperature discharged from the hot water storage means is equal to or higher than the hot water supply demand set water temperature, hot water is directly supplied via the bypass line without passing through the temperature raising means. The warming operation means realizes immediate hot water supply by circulating hot water heated by the temperature raising means in the order of constant temperature raising means → hot water supply line → warming operation pump → hot water supply line terminal → return line → temperature raising means. . Further, by not returning the hot water heated by the temperature raising means to the hot water storage tank, the amount of exhaust heat recovered from the internal combustion engine side entering the hot water storage tank can be increased and the operating time of the temperature raising means can be shortened.

[0007]

Embodiments of the present invention will be described in detail with reference to FIG.
In FIG. 1, 1 is a power generation system that drives a generator by a gas engine to generate electric power, 2 is cooling water of the gas engine, an exhaust heat recovery line that recovers exhaust gas heat, and 3 is a hot water tank as hot water storage means. The exhaust heat recovery line 2 is configured to give exhaust heat to the water in the hot water storage tank 3 via the exhaust heat recovery heat exchanger 4 incorporated in the hot water storage tank 3. Reference numeral 8 denotes a water supply line for supplying water into the hot water storage tank 3, and the water supply line 8 is provided with a water supply valve 8b so that the water level sensor 8a detects the water level in the hot water storage tank 3 and always maintains a constant water level. A water supply control means for controlling is attached. However,
This water supply control means can be eliminated by adopting a system of automatically supplying water by tap water pressure when the water level in the hot water storage tank 3 is lowered by hot water supply. 9 is a hot water supply line,
13 is a cooling line, and 14 is a cooling tower.

Reference numeral 15 denotes a gas water heater (hereinafter referred to as "heater") of a pre-stopping type, which can set a hot water outlet temperature as an example of temperature raising means attached to the hot water supply line 9, and 16 denotes an outlet of the heater 15. Water temperature detection sensor attached to the hot water supply line 9b on the side, 11 is a terminal 9a of the hot water supply line 9b and the temperature raising device 1
A return line connecting the inlet side of 5 and 12 is a heat retention operation pump attached to the outlet side of the temperature raising device 15. Reference numeral 17 is a bypass line as a direct hot water supply means which branches the hot water supply line 9 and is connected to the hot water supply line 9b by a three-way valve 18 on the upstream side of the heating device 15, and 19 is a water temperature detection for detecting the water temperature at the outlet of the hot water storage tank 3. When the water temperature detection sensor 19 detects a certain water temperature or higher, the three-way valve 18 is switched to the bypass line 17 side to directly connect the hot water storage tank 3
Hot water inside can be supplied to the hot-water tap 10.

The operation of the above embodiment will be described below. A water level sensor 8a and a water supply valve 8b automatically supply water to the hot-water storage tank 3 in an amount suitable for tapping hot water through a water supply line 8. Exhaust heat from the gas engine that drives the generator enters the exhaust heat recovery exchanger 4 in the hot water storage tank 3 via the exhaust heat recovery line 2 and gives heat to the water in the hot water storage tank 3 there. Then return to the gas engine again. By this action, the exhaust heat is recovered by the water stored in the hot water storage tank 3. As a result, the temperature of the water in the hot water storage tank 3 rises. When there is a hot water supply demand and the water temperature detected by the water temperature detection sensor 19 is lower than the hot water supply demand set water temperature, the warmer 15 is driven and the hot water supply line 9b to the return line 1 until the hot water supply demand set water temperature is reached.
Heat the warm water flowing through 1. On the other hand, water temperature detection sensor 1
When the water temperature in the hot water storage tank 3 detected at 9 is equal to or higher than the hot water supply demand set water temperature, the three-way valve 18 is switched and the hot water tap 1 is directly passed through the bypass line 17.
Hot water is supplied to 0. In the heat retention operation, the heat retention operation pump 12 is driven to operate the temperature raising device 1 regardless of whether there is a demand for hot water supply.
The warm water heated by 5 is heated by the heater 15 → hot water supply line 9b →
The warm-keeping pump 12 → hot water supply line terminal 9a → return line 11 → heater 15 circulates to prepare for hot water supply immediately.

[0010]

The effects of the present invention are as follows. a. In the hot water storage means, only the water having the temperature raised by the heat exchanger for recovering exhaust heat is stored, and the conventional means for heating up to about 70 ° C using the auxiliary heating boiler is eliminated and the temperature is raised. The warm water heated by the warming means is not returned to the hot water storage means as in the conventional case. As a result, the water temperature in the hot water storage means is determined by the heat recovered from the exhaust heat, and if there is a large demand for hot water supply, the water temperature in the hot water storage means will drop rapidly,
The difference between the exhaust heat and the water temperature becomes large, and the efficiency of recovering the exhaust heat from the internal combustion engine side improves. Comparing this point with the conventional example,
In the case of the present invention, the exhaust heat was collected for a total of about 10 hours in the 12-hour continuous operation. However, in the system for heating the inside of the hot water tank to about 70 ° C. by attaching the conventional auxiliary heating boiler, the cooling tower is driven. Was about 9 hours, and the exhaust heat recovery operation was only 3 hours. b. Since the temperature raising means raises the temperature corresponding to the hot water supply demand set water temperature, there is no inconvenience that the demand set water temperature may not be obtained because the water temperature in the hot water storage tank is low as in the conventional case. c. Unlike the conventional case, high temperature water of about 70 ° C. is not stored in the hot water storage means, so natural heat dissipation loss is small. d. Since the temperature raising means raises only the hot water supply demand water amount, efficient water temperature heating is possible. e. By using the temperature raising means capable of controlling the temperature raising temperature, it is possible to obtain hot water of 80 to 90 ° C. as compared with the conventional example in which hot water of about 70 ° C. or higher could not be obtained. f. Since the hot water supply line is provided with the temperature raising means, it is not necessary to set a large capacity of the hot water storage tank as in the conventional case. As a result, the hot water storage tank can be downsized. g. As the temperature raising means, for example, a small stop type water heater can be used. h. By installing the temperature raising means close to the hot water tap, the return line piping distance can be shortened as compared with the conventional example in which the hot water storage tank is piped.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of a cogeneration system embodying the present invention.

FIG. 2 is an explanatory diagram of a conventional cogeneration system.

[Explanation of symbols]

 1 Power Generation System 2 Exhaust Heat Recovery Line 3 Hot Water Tank 4 Exhaust Heat Recovery Heat Exchanger 5 Auxiliary Heating Boiler 6 Water Temperature Sensor 7 Auxiliary Heat Exchanger 8 Water Supply Line 8a Water Level Sensor 8b Water Supply Valve 9 Hot Water Supply Line 9a Terminal 9b Hot Water Supply Line 10 … Hot water tap 11 Return line 12 Heat retention pump 13 Cooling line 14 Cooling tower 15 Heater 16 Water temperature detection sensor 17 Bypass line 18 Three-way valve 19 Water temperature detection sensor

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location F24D 17/00

Claims (4)

[Claims] 1. A hot water storage means incorporating a heat exchanger for recovering exhaust heat, a water supply line connected to the hot water storage means, a hot water supply line for supplying hot water stored in the hot water storage means to a hot water tap, and the hot water supply line A temperature raising means attached to the hot water supply line for heating the hot water supplied from the hot water supply tap to the hot water supply tap, the temperature of the hot water supplied to the hot water supply tap from the hot water supply line is detected by a water temperature sensor, and the detected temperature is below a set value. In the case of, the hot water supply temperature control means for driving the temperature raising means to raise the water temperature to a set temperature, the hot water supply line is provided with a bypass line bypassing the temperature raising means, and the hot water supply water temperature is equal to or higher than a set value. In this case, a direct hot water supply means for opening the bypass line, a terminal of the hot water supply line and an inlet side of the temperature raising means are connected by a return line and attached to this return line. Thermal insulation operation A cogeneration system consisting of a thermal insulation operation means that drives the pump to perform thermal insulation operation at all times. 2. The cogeneration system according to claim 1, wherein a gas water heater that starts driving when the water pressure on the hot water supply side drops below a certain value is used as the temperature raising means. 3. The cogeneration system according to claim 1, wherein the temperature raising means is capable of freely setting the temperature raising temperature. 4. The cogeneration system according to claim 1, wherein the hot water storage tank is provided with a plurality of hot water supply lines and return lines each having a temperature raising means and a heat retention operation means.