JP4408770B2 - Hot water storage heat recovery system - Google Patents

Description

  The present invention provides hot water heated by exhaust heat collected from exhaust heat generators such as engine-driven generators and fuel cells, which are installed mainly in general households, such as each detached house or each apartment house. The present invention relates to a hot water storage type exhaust heat recovery system that stores in a hot water storage tank and supplies hot water stored in the hot water storage tank to a hot water supply location such as a kitchen or a bath.

  Such a hot water storage type exhaust heat recovery system includes a heating unit that heats hot water using exhaust heat recovered from the exhaust heat generation unit, a hot water storage tank that stores hot water heated by the heating unit in a form that forms temperature stratification, and a heating unit. Supply intermittent means for intermittently supplying hot water from the means to the hot water storage tank, and when the hot water storage tank is less than full, the temperature of the hot water supplied from the heating means to the hot water storage tank is higher than the target hot water temperature. Supply state control means for controlling the operation of the supply interrupting means so as to supply hot water to the hot water storage tank.

  Accordingly, the supply state control means of the hot water storage type exhaust heat recovery system is configured to change the supply intermittent means from the heating means to the hot water storage tank if the supplied hot water temperature is equal to or higher than a preset target hot water temperature (for example, 60 ° C.). In the hot water storage state that permits the supply of hot water, conversely, if the supplied hot water temperature is lower than the target hot water temperature, the supply intermittent means is set in a non-hot water storage state that prohibits the supply of hot water from the heating means to the hot water storage tank. Thus, hot water above the target hot water storage temperature can always be supplied and stored in the hot water storage tank.

Further, in such a hot water storage type exhaust heat recovery system, hot water having a temperature equal to or higher than the target hot water temperature is stored in the entire hot water storage tank, and the upper hot water temperature and the hot water storage tank, which are the temperatures of hot water stored above the hot water storage tank. It is possible to determine that the hot water storage tank is full when the stored hot water temperature difference, which is the difference with the temperature of the lower stored hot water stored below, becomes equal to or less than the reference temperature difference.
When the hot water storage tank is full, the supply intermittent means is always set to a non-hot water storage state that prohibits the supply of hot water from the heating means to the hot water storage tank without supplying hot water heated by the heating means to the hot water storage tank. By supplying to a heat radiating means such as a radiator to dissipate heat, the exhaust heat of the exhaust heat generation part may be released to prevent abnormal temperature rise of the exhaust heat generation part (see, for example, Patent Document 1). .

JP 2003-214705 A

  However, in the conventional hot water storage type exhaust heat recovery system, if the stored hot water temperature difference is less than the reference temperature difference and the hot water storage tank is determined to be full, the hot water storage tank In some cases, the temperature of the hot and cold water stored by the heat dissipation in the water drops throughout the whole.

  Moreover, in the conventional hot water storage type exhaust heat recovery system, it is desired to improve the thermal efficiency by effectively using the exhaust heat of the exhaust heat generation unit.

  The present invention has been made in view of the above-mentioned problems, and its purpose is excellent while maintaining the temperature of hot water stored in the hot water storage tank as high as possible when the hot water storage tank is full. The point is to provide a hot water storage type exhaust heat recovery system that exhibits thermal efficiency.

A hot water storage type exhaust heat recovery system according to the present invention for achieving the above object comprises a heating means for heating hot water with exhaust heat recovered from an exhaust heat generation unit,
A hot water storage tank for storing hot water heated by the heating means in a form for forming temperature stratification;
Supply intermittent means for intermittently supplying hot water from the heating means to the hot water storage tank;
A full state determination means for determining whether a low temperature hot water exists below the hot water tank or a full state where high temperature hot water is stored in the entire hot water tank,
If the hot water temperature, which is the temperature of hot water supplied from the heating means to the hot water storage tank, is equal to or higher than the target hot water temperature when the full state determination means is in the less full state, the hot water is stored in the hot water storage. A hot water storage type exhaust heat recovery system provided with a supply state control means for controlling the operation of the supply intermittent means to supply to a tank, the first characteristic configuration is:
The heating means is configured to heat hot water circulating in the hot water circulation path,
The hot water storage tank has hot water flowing upward from an inflow portion connected to the hot water circulation path, and is connected downstream of the connection portion of the inflow portion of the hot water circulation path and upstream of the heating means. It is configured so that downward hot water flows out from the outflow part,
The supply interrupting means switches between a hot water storage state permitting supply of hot water from the hot water circulation path to the hot water storage tank and a non-hot water storage state prohibiting supply of hot water from the hot water circulation path to the hot water storage tank. Configured,
The supply state control means is configured to supply the hot water to the hot water storage tank when the supply hot water temperature is equal to or higher than the upper hot water temperature when the full state determination means is in the full state. A hot water storage type exhaust heat recovery system configured to control the operation of the intermittent means.

According to the first characteristic configuration, even when the hot water storage tank is full, the supply state control means moves the supply intermittent means from the heating means to the hot water storage if the supplied hot water temperature is equal to or higher than the stored hot water temperature. By setting the hot water storage state to allow the supply of hot water to the tank, hot water that always exceeds the actual hot water temperature can be supplied to the hot water tank, and the hot water temperature in the hot water tank can be maintained as high as possible. .
Further, when the hot water storage tank is full, the supply state control means supplies the hot water from the heating means to the hot water tank only when the hot water temperature is lower than the stored hot water temperature. The non-hot water storage state to be prohibited is set, and the exhaust heat recovered from the exhaust heat generation section is released. Therefore, the heat radiation amount can be reduced as much as possible, and excellent thermal efficiency can be exhibited.

Further, according to the first characteristic configuration, when the temperature of the hot water heated by the heating means is relatively high, the supply intermittent means is set in the hot water storage state, and the hot water heated by the heating means is supplied to the inflow portion. The hot water in the hot water storage tank is allowed to flow into the upper part of the hot water storage tank and the hot water in the lower part of the hot water storage tank can be discharged to the heating means through the outflow part. It can be stored in a form that forms temperature stratification. On the other hand, when the temperature of the hot water heated by the heating means is relatively low, the supply intermittent means is set to the non-hot water storage state, and the hot water circulation path is made without flowing the hot water heated by the heating means into the hot water storage tank. it is possible to circulate the, Ru can keep the temperature stratification formed in the hot water storage tank.

In addition to the first feature configuration, the second feature configuration of the hot water storage type exhaust heat recovery system according to the present invention is located downstream of the connection portion of the inflow portion of the hot water circulation path and upstream of the heating means. The heat dissipating means for dissipating hot water is provided.

According to the second characteristic configuration, the hot water heated by the heating means is supplied to the heat radiating means to dissipate heat, thereby releasing the exhaust heat collected from the exhaust heat generating section, thereby causing an abnormal rise of the exhaust heat generating section. Temperature can be prevented.

Embodiments of the present invention will be described with reference to the drawings.
The hot water storage type exhaust heat recovery system shown in FIG. 1 includes an exhaust heat generation unit 10, a heating unit 11 that heats hot water with the exhaust heat recovered from the exhaust heat generation unit 10, and hot water heated by the heating unit 11. , A hot water storage tank 14 for storing in a form for forming temperature stratification, and a supply intermittent means 18 for intermittently supplying hot water from the heating means 11 to the hot water storage tank 14, and the supply intermittent means 18 and other auxiliary devices. The control apparatus 20 which performs operation control of these is provided.

First, various configurations included in the hot water storage type exhaust heat recovery system will be described.
The exhaust heat generator 10 includes a combined heat and power supply device 1 such as a fuel cell or an engine drive generator, and a cooling water circulation path 2 and a circulation pump 3 for circulating cooling water for cooling the inside of the combined heat and power supply device 1. .
That is, the hot water storage type exhaust heat recovery system is configured as a cogeneration system that generates electricity and heat by the cogeneration apparatus 1.

  The heating means 11 is configured to heat the hot water circulating in the hot water circulation path 12 in a state where the circulation pump 13 is operated, and more specifically, the cooling water circulating in the cooling water circulation path 2 and the hot water circulation path 12 are connected to each other. It is configured as a heat exchanger for exhaust heat recovery that performs heat exchange with circulating hot water.

The hot water storage tank 14 has hot water flowing upward from an inflow portion 14 a connected to the hot water circulation path 12, and is connected to a downstream side of the connection portion of the inflow portion 14 a of the hot water circulation path 12 and an upstream side of the heating means 11. The downward hot water flows out from the outflow portion 14b.
Further, on the downstream side of the heating means 11 of the hot water circulation path 12 and the upstream side of the connection portion with the inflow portion 14a, a supply hot water temperature that is the temperature of hot water supplied from the heating means 11 to the hot water storage tank 14 is set. A hot water temperature sensor 17 for detection is provided.

  Moreover, the hot water storage tank 14 is configured in a sealed manner, and a water supply path 31 for supplying tap water or tap water decompressed by a pressure reducing valve (not shown) is connected to the lower side, and a hot water supply path 30 is connected to the upper side. As hot water is sent from above through the hot water supply passage 30 by opening a hot water tap (not shown) or the like, water is supplied downward through the water supply passage 31.

  Further, the hot water storage tank 14 includes an upper stored hot water temperature sensor 15 that detects an upper stored hot water temperature that is the temperature of hot water stored above the hot water storage tank 14, and hot water stored below the hot water storage tank 14. A lower stored hot water temperature sensor 16 for detecting a lower stored hot water temperature, which is a temperature, is provided.

  The supply intermittent means 18 is composed of a three-way switching valve 19 provided at a connection portion between the hot water circulation path 12 and the outflow portion 14b of the hot water storage tank 14, and the three-way switching valve 19 on the downstream side of the hot water circulation path 12 is provided. By opening the connection port on the outflow portion 14b side of the three-way switching valve 19 while always opening the connection port, a hot water storage state allowing the supply of hot water from the hot water circulation path 12 to the inflow portion 14a of the hot water storage tank 14 is established. By closing the connection port with the outflow portion 14b of the three-way switching valve 19, a non-hot water storage state in which the supply of hot water from the hot water circulation path 12 to the inflow portion 14a of the hot water storage tank 14 is prohibited.

  Further, the connection port on the upstream side of the hot water circulation path 12 of the three-way switching valve 19 is closed during the hot water storage state so that the entire amount of hot water in the hot water circulation path 12 is supplied to the hot water storage tank 14 side. However, it may be configured such that it is opened during the hot water storage state and a part of the hot water in the hot water circulation path 12 is supplied to the hot water storage tank 14 side.

  The control device 20 controls the operation of the full state determination means 21 for determining whether the hot water storage tank 14 is in a full state or a full state, and the supply interruption means 18 according to the determination result of the full state determination means 21. It is comprised so that it may function as the supply state control means 22 to perform, and the detailed structure of each means 21 and 22 is demonstrated below.

The full state determination means 21 obtains the difference between the upper stored hot water temperature detected by the upper stored hot water temperature sensor 15 and the lower stored hot water temperature detected by the lower stored hot water temperature sensor 16 as the stored hot water temperature difference.
When the stored hot water temperature difference is greater than or equal to a preset reference temperature difference, hot water is stored above the hot water storage tank 14, but low temperature hot water is stored below the storage tank 12. Since it can be determined that it exists, it is determined that the hot water storage tank 14 is in the less full state.
On the other hand, when the stored hot water temperature difference is less than a preset reference temperature difference, it can be determined that hot hot water is stored in the entire hot water storage tank 14, and therefore the hot water storage tank 14 is full. judge.

  When the supply state control means 22 determines that the hot water storage tank 14 is less full by the full state determination means 21, the supply hot water temperature detected by the supply hot water temperature sensor 17 is equal to or higher than a preset target hot water storage temperature. The operation of the supply interrupting means 18 is controlled so as to supply hot water to be supplied to the hot water storage tank 14.

Specifically, when the hot water storage tank 14 is in the less full state, the supply state control means 22 sets the supply intermittent means 18 to the hot water storage state if the supply hot water temperature is equal to or higher than the target hot water storage temperature set to 60 ° C., for example. If hot water is stored in the hot water storage tank 14 and the supplied hot water temperature is lower than the target hot water temperature, the supply intermittent means 18 is set in a non-hot water storage state and the hot water is circulated in the hot water circulation path 12 without being stored in the hot water storage tank 14.
Then, the supply state control means 22 always supplies hot water above the target hot water temperature above the hot water storage tank 14 in the lower cup state. The hot water storage tank 14 supplies hot water above the target hot water temperature. It is stored in a state in which temperature stratification is formed.

  Further, when the supply state control means 22 determines that the hot water storage tank 14 is full by the full state determination means 21, the supply hot water temperature detected by the supply hot water temperature sensor 17 is stored in the hot water storage tank 14. It is configured to control the operation of the supply intermittent means 18 so as to supply hot water having a temperature equal to or higher than the temperature of the hot water stored, that is, the upper stored hot water temperature detected by the upper stored hot water temperature sensor 15 to the hot water storage tank 14. Yes.

Specifically, when the hot water storage tank 14 is full, the supply state control means 22 stores the hot water in the hot water storage tank 14 by setting the supply intermittent means 18 to the hot water storage state if the hot water temperature is equal to or higher than the upper stored hot water temperature. If the supply hot water temperature is lower than the upper storage hot water temperature, the supply intermittent means 18 is set in a non-hot water storage state, and the hot water is circulated in the hot water circulation path 12 without being stored in the hot water storage tank 14.
The supply state control means 22 always supplies hot water above the upper hot water storage temperature above the full hot water storage tank 14 so that the hot water temperature in the hot water storage tank 14 is kept as high as possible. Is done.

Further, the hot water storage type exhaust heat recovery system is provided with a heat radiating means 25 for radiating hot water downstream of the connecting portion of the outflow portion 14 b of the hot water circulation path 12 and upstream of the heating means 11.
The heat dissipating means 25 ventilates the heat dissipating heat exchanger 26 in which a flow path is formed so as to increase the surface area of the flowing hot water and the heat dissipating heat exchanger 14a, and the heat dissipating heat exchanger 26 It is comprised with the fan 27 for improving the heat dissipation effect of the hot water which flows through.
Therefore, the cooling water circulating in the cooling water circulation path 2 in the heating means 11 can be sufficiently cooled by operating the heat radiation means 25 to radiate the hot water supplied to the heating means 11 in the hot water circulation path 11. It is possible to prevent abnormal temperature rise of the combined heat and power supply device 11.

The heat dissipating means 25 may be operated at all times, but is operated only when the temperature of the hot water supplied to the heating means 11 is equal to or higher than an allowable temperature to suppress a decrease in thermal efficiency due to excessive heat dissipation. It can also be configured as follows.
The heat radiating means 25 may be always supplied with hot water regardless of whether or not the heat radiating means 25 is operated, but hot water is supplied to the heat radiating means 25 only when the heat radiating means 25 is operated. When the heat radiating means 25 is not operated, the heat radiating means 25 may be bypassed and hot water may flow.

  Furthermore, as shown in FIG. 2, the heat radiating means 25 may be provided on the downstream side of the connection portion of the inflow portion 14a of the hot water circulation path 12 and on the upstream side of the connection portion of the outflow portion 14b.

In the case where the heat dissipating means 25 is provided at the location shown in FIG. 2, when the hot water storage tank 14 is full and the supply interrupting means 18 is in the hot water storage state, the outflow portion 14b of the hot water storage tank 14 enters the hot water circulation path 12. In order to prevent the hot water from being discharged and being supplied to the heating means 11 at a high temperature, the connection port on the upstream side of the hot water circulation path 12 of the three-way switching valve 19 is opened, and the hot water storage tank 14 is opened. The hot hot water discharged from the outflow portion 14 b of the hot water circulation path 12 is supplied to the heating means 11 in a state of being mixed with the low temperature hot water cooled by the heat radiating means 25.
Further, the opening degree of the connection port on the upstream side of the hot water circulation path 12 of the three-way switching valve 19 is determined based on the temperature of the hot water discharged from the outflow portion 14b of the hot water storage tank 14 to the hot water circulation path 12, that is, the lower stored hot water temperature sensor 16. The temperature of hot water supplied to the heating means 11 can be suppressed to an allowable temperature or less while increasing the amount of hot water supplied to the hot water storage tank 14 as much as possible by adjusting it according to the temperature of the lower stored hot water detected in step. it can.

[Another embodiment]
(1) In the above embodiment, the hot water storage type exhaust heat recovery system according to the present invention has been described by taking the exhaust heat generation unit 10 provided with the cogeneration apparatus 1 as an example, but the internal structure of the exhaust heat generation unit 10 The configuration for recovering exhaust heat from the exhaust heat generator 10 can be modified in various forms.

(2) In the above embodiment, the hot water storage tank 14 is configured to be hermetically sealed so that tap water is supplied from the water supply passage 31 and hot water in the hot water storage tank 12 is sent out through the hot water supply passage 30. However, the structure of the hot water storage tank 14 and the hot water supply mechanism can be modified in various forms.

(3) In the above embodiment, the supply intermittent means 18 for intermittently supplying hot water from the heating means 11 to the hot water storage tank 14 is provided at the connection portion between the hot water circulation path 12 and the outflow portion 14b of the hot water storage tank 14. Although the three-way switching valve 19 is configured, the supply interrupting means 18 can be modified to another configuration, such as configured by a plurality of valves, and the installation location can also be modified.

(4) In the above embodiment, whether or not the hot water storage tank 14 is full is determined based on whether or not the stored hot water temperature difference between the upper hot water temperature and the lower hot water temperature of the hot water tank 14 is less than the reference temperature difference. However, the amount obtained by subtracting the amount of hot water consumed by hot water supply from the amount of hot water supplied to the inflow portion 14a of the hot water storage tank 14 is obtained as the amount of hot water stored in the hot water storage tank 14, and the amount of hot water stored It may be determined whether or not it is full.

( 5 ) In the above embodiment, the heat dissipating means 25 is provided and the hot water supplied to the heating means 11 is cooled. For example, the heat and power supply apparatus 11 includes a heat dissipating means such as a radiator. When there is no need to cool the hot water supplied to the heating means 11, the heat radiating means 25 may be omitted.

Schematic configuration diagram showing an embodiment of a hot water storage type exhaust heat recovery system Schematic configuration diagram showing another embodiment of a hot water storage type exhaust heat recovery system

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Waste heat generation part 11: Heating means 14: Hot water storage tank 18: Supply intermittent means 22: Supply state control means 12: Hot water circulation path 14a: Inflow part 14b: Outflow part 25: Radiation means

Claims (2)

A heating means for heating the hot water with the exhaust heat recovered from the exhaust heat generation section;
A hot water storage tank for storing hot water heated by the heating means in a form for forming temperature stratification;
Supply intermittent means for intermittently supplying hot water from the heating means to the hot water storage tank;
A full state determination means for determining whether a low temperature hot water exists below the hot water tank or a full state where high temperature hot water is stored in the entire hot water tank,
If the hot water temperature, which is the temperature of hot water supplied from the heating means to the hot water storage tank, is equal to or higher than the target hot water temperature when the full state determination means is in the less full state, the hot water is stored in the hot water storage. A hot water storage type exhaust heat recovery system provided with a supply state control means for controlling the operation of the supply intermittent means to supply to a tank,
The heating means is configured to heat hot water circulating in the hot water circulation path,
The hot water storage tank has hot water flowing upward from an inflow portion connected to the hot water circulation path, and is connected downstream of the connection portion of the inflow portion of the hot water circulation path and upstream of the heating means. It is configured so that downward hot water flows out from the outflow part,
The supply interrupting means switches between a hot water storage state permitting supply of hot water from the hot water circulation path to the hot water storage tank and a non-hot water storage state prohibiting supply of hot water from the hot water circulation path to the hot water storage tank. Configured,
The supply state control means is configured to supply the hot water to the hot water storage tank when the supply hot water temperature is equal to or higher than the upper hot water temperature when the full state determination means is in the full state. A hot water storage type exhaust heat recovery system configured to control the operation of the intermittent means. The hot water storage-type exhaust heat recovery system according to claim 1, further comprising a heat dissipating means for radiating the hot water downstream of the connecting portion of the inflow portion of the hot water circulation path and upstream of the heating means .

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