JP2010266166A - Hot water storage type exhaust heat recovery system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that heat radiation is increased as a heat recovering pipe is long and exposed outdoors, in a configuration that a fuel cell unit and a hot water storage unit are separated and connected by the heat recovering pipe. <P>SOLUTION: In this hot water storage type exhaust heat recovery system, a heat exchanger 102, a circulation pump 103, a switch 109 of a heat recovering water circulation circuit and a bypass pipe 110 are disposed in the fuel cell unit, and the fuel cell unit 201 and a hot water storage tank 104 in a hot water storage unit 202 independently disposed are connected by a heat recovering pipe A105 and a heat recovery pipe C107. According to this constitution, the heat recovering water can pass in the heat recovering pipe between the fuel cell unit and the hot water storage unit in a state of suppressing heat radiation with outside air flowing in the fuel cell unit when passing through the bypass pipe. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a hot water storage type exhaust heat recovery system that stores heat as hot water in a hot water storage tank that has left the exhaust heat in a cogeneration system such as a fuel cell cogeneration system.

  As a conventional hot water storage type exhaust heat recovery system, there has been a fuel cell cogeneration system (see, for example, Patent Document 1). FIG. 4 shows a conventional fuel cell cogeneration system described in Patent Document 1. In FIG.

  In FIG. 4, the fuel cell 101 discharges surplus heat by passing it to the heat recovery water by the heat exchanger 102. This heat recovery water is conveyed from the lower part of the hot water storage tank 104 through the heat recovery pipe A105 and the heat recovery pipe B106 by the circulation pump 103. The heat recovery water heated by surplus heat of the fuel cell 101 in the heat exchanger 102 is detected by the heat exchange temperature sensor 108, and when the temperature is higher than the temperature of the upper part of the hot water storage tank 104, the heat recovery pipe C107 stores the hot water storage. It is conveyed to the upper part of the tank 104. When the temperature of the heat recovery water heated here is lower than the temperature of the upper part of the hot water storage tank 104, the changeover valve 109 conveys the heat recovery water to the junction of the heat recovery pipe A105 through the bypass circuit 110 and circulates in the circuit.

JP-A-11-223385 (FIG. 1)

  However, in the conventional configuration, the heating temperature of the heat recovery water of the heat exchanger of the fuel cell is controlled to a temperature that should be accumulated in the hot water storage tank, and switching is performed depending on whether or not the temperature is to be accumulated in the hot water storage tank in the process. The valve is switched between a hot water storage tank and a bypass circuit. Looking at the current system installation, the fuel cell unit and hot water storage unit are separated from each other due to the installation space and connected by heat recovery piping. Moreover, the bypass circuit is installed in the hot water storage unit in order to increase the amount of water held in the circuit when flowing through the bypass circuit. For this reason, since heat recovery piping is long and exposed to the outdoors, the amount of heat radiation increases. Since the heat recovery water passes through the heat recovery pipe C both when the hot water tank passes and when the bypass circuit passes, the heat is continuously radiated. In the case of circulating in the bypass circuit without storing heat in the hot water storage tank, there was a problem that a heat dissipation loss occurred in the reciprocation.

  The present invention solves the above-mentioned conventional problems, because the amount of heat recovery is small like a hot water storage type cogeneration system using a fuel cell, and in particular, the installation form is separated by the main body unit and the hot water storage unit. An object of the present invention is to provide a hot water storage type waste heat recovery system that takes into consideration even when heat radiation in a heat recovery pipe, which was not assumed in the conventional configuration, is large, so that heat recovery water can be conveyed.

In order to solve the above conventional problems, a hot water storage type exhaust heat recovery system of the present invention includes a heat exchanger for exchanging exhaust heat with heat recovery water in the fuel cell unit, and a fuel cell unit. A heat pump that circulates heat recovery water, a hot water storage unit having a hot water storage tank for storing the exhaust heat of the fuel cell as hot water, and heat recovery that sends water in the hot water storage tank in the hot water storage unit to the circulation pump as heat recovery water Pipe A, heat recovery pipe B for sending heat recovery water from the circulation pump to the heat exchanger of the fuel cell unit, and heat recovery from the heat exchanger of the fuel cell unit and sending the heated heat recovery water to the upper part of the hot water storage tank Heat recovery pipe C, a switch to a circuit different from the path to the upper part of the hot water storage tank in the fuel cell unit in the middle of the heat recovery pipe C, and heat recovery water switched by this switch to recover heat Circulation of pipe A Amplifier is before that a bypass pipe passing through the fuel cell unit for combining the heat recovery pipe A in.

  With this configuration, the flow of heat recovery water between the fuel cell unit and the hot water storage unit of the heat recovery pipe can flow through the fuel cell unit when passing through the bypass pipe and can suppress heat dissipation from the outside air. it can.

  According to the hot water storage type exhaust heat recovery system of the present invention, when the heat recovery water between the fuel cell unit and the hot water storage unit of the heat recovery pipe is passed through the bypass pipe, Since the fuel cell unit prevents contact with the outside air due to the flow, it is possible to suppress the heat radiation caused by the temperature difference between the heat recovery water and the outside air.

Configuration diagram of hot water storage type exhaust heat recovery system in Embodiment 1 of the present invention Configuration diagram of hot water storage type exhaust heat recovery system in Embodiment 2 of the present invention Configuration diagram of hot water storage type exhaust heat recovery system in Embodiment 3 of the present invention Configuration diagram of conventional fuel cell cogeneration system

  1st invention uses the heat which collect | recovered and collect | recovered the exhaust heat of this fuel cell as a fuel cell unit which is an apparatus which has a heat exchanger for exchanging exhaust heat between heat recovery water as warm water A hot water storage unit having a hot water storage tank for storing, a circulation pump for circulating heat recovery water in the fuel cell unit, and circulating water from the hot water storage tank as heat recovery water from the bottom connection port in the hot water storage tank in the hot water storage unit Heat recovery pipe A that is sent to the pump, heat recovery pipe B that sends the heat recovery water from the circulation pump to the heat exchanger of the fuel cell unit, and heat recovery water that is heated and recovered from the heat exchanger of the fuel cell unit The heat recovery pipe C constituting the path for sending the hot water storage tank from the upper entrance of the hot water storage tank in the hot water storage unit to the hot water storage tank is different from the path to the upper part of the hot water storage tank in the fuel cell unit in the middle of the heat recovery pipe C. And switch to a circuit, in which the switched heat recovery water at this switch with a bypass pipe passing through the fuel cell unit for combining the heat recovery pipe A in the circulation pump before the heat recovery pipe A.

  In particular, the second invention is a circuit configuration having a buffer tank in the path between the junction of the bypass pipe and the heat recovery pipe A and the inlet of the heat exchanger in the fuel cell unit in the first invention. is there.

According to a third aspect of the invention, in particular, in the first or second aspect of the invention, a heat exchange temperature sensor that detects the temperature of the heat recovery water on the path between the outlet of the heat exchanger and the switch, and a heat exchanger A heat input temperature sensor for detecting the temperature of the heat exchanger inlet of the heat recovery water on the path between the junction of the inlet, the bypass pipe and the heat recovery pipe A, and the heat recovery pipe A in the hot water storage unit to the hot water storage tank The temperature of the hot water storage temperature sensor that detects the temperature of the heat recovery water and the temperature of the heat exchange temperature sensor that controls the temperature of the heat exchange temperature sensor so that the temperature of the heat recovery water heated by the heat exchanger becomes the target temperature for hot water storage. When the function and switch are storing hot recovered water in the hot water storage tank on the hot water storage tank side, if it is determined that the heat release is large from the temperature information of the heat transfer temperature sensor and the hot water storage temperature sensor, the heat output temperature Control the temperature of the sensor from the hot water storage target temperature To a second target temperature range not interfering, switching to the bypass circuit switch when the temperature of the heat 交出 temperature sensor is lowered to the second target temperature,
When the temperature of the heat input temperature sensor rises to the second target temperature, the control temperature of the heat exchange temperature sensor was changed to the hot water storage target temperature, and the temperature of the heat exchange temperature sensor became higher than the switching set temperature. By the way, it has a control function to switch the switch to the hot water storage tank side.

  Embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a configuration diagram of a hot water storage type exhaust heat recovery system according to Embodiment 1 of the present invention. In FIG. 1, the same components as those in FIG.

  In FIG. 1, a fuel cell unit 201, which is a device having a heat exchanger 102 for exchanging exhaust heat with heat recovery water, and the heat recovered and recovered from the exhaust heat of the fuel cell 101 are used as hot water. A hot water storage unit 202 having a hot water storage tank 104 for storing, a circulation pump 103 for circulating heat recovery water in the fuel cell unit 201, and a hot water storage tank 104 from a bottom connection port in the hot water storage tank 104 in the hot water storage unit 202. Recovery pipe A105 for sending the water as heat recovery water to the circulation pump 103, heat recovery pipe B106 for sending the heat recovery water from the circulation pump 103 to the heat exchanger 102 of the fuel cell unit 201, and heat exchange for the fuel cell unit 201 Hot water is collected from the upper entrance of the hot water storage tank 104 in the hot water storage unit 202 by collecting heat from the vessel 102 and heating the recovered heat water. The heat recovery pipe C107 that constitutes a path for sending it into the 104, the switch 109 to a circuit different from the path to the upper part of the hot water storage tank 104 in the fuel cell unit 201 in the middle of the heat recovery pipe C107, and this switching The heat recovery water switched by the vessel 109 is provided with a bypass pipe 110 that passes through the fuel cell unit 201 for joining the heat recovery pipe A105 before the circulation pump 103 of the heat recovery pipe A105.

  More specifically, in FIG. 1, the fuel cell 101 in the fuel cell unit 201 discharges excess heat by passing it to the heat recovery water by the heat exchanger 102. This heat recovery water is conveyed from the lower part of the hot water storage tank 104 in the hot water storage unit 202 through the heat recovery pipe A105, the circulation pump 103, and the heat recovery pipe B106. Further, the temperature of the heat recovery water heated by the heat exchanger 102 with the excess heat of the fuel cell 101 is detected by the temperature sensor 108, and when the heat recovery water is stored in the hot water storage tank 104 based on the temperature, the switching valve 109 is stored in the hot water. When switching to the tank side and not storing hot water, the switching valve 109 is switched to the bypass circuit 110 side.

  According to such a configuration, when the switching valve 109 is switched to the bypass circuit 110 side, the circulation circuit configuration configured from the bypass circuit 110 through the circulation pump 103 and the heat exchanger 102 to the switching device is entirely inside the fuel cell unit 201. Therefore, even if the fuel cell unit 201 and the hot water storage unit 202 are separated from each other, heat loss to the outside air of the circulation circuit can be eliminated.

(Embodiment 2)
FIG. 2 is a configuration diagram of a hot water storage type exhaust heat recovery system according to Embodiment 2 of the present invention. 2, the same components as those in FIGS. 1 and 4 are denoted by the same reference numerals, and the description thereof is omitted.

  In FIG. 2, the buffer tank 203 is installed between the outlet of the circulation pump 103 and the inlet of the heat exchanger 102. Here, the buffer tank 203 may be provided between the bypass circuit 110, the junction 110A of the heat recovery pipe A, and the inlet of the circulation pump 103. Further, it may be configured in the circulation pump 103.

According to such a configuration, it is possible to lengthen the switching cycle of the switch 103 by increasing the volume of the circulation circuit configured when the switch 109 is switched by the volume of the buffer tank 203, and the temperature of the switch due to frequent switching is increased. By mitigating the occurrence of frequent fluctuations, it is possible to mitigate the impact on the durability performance of components on the circulation circuit.

(Embodiment 3)
FIG. 3 is a configuration diagram of a hot water storage type exhaust heat recovery system according to Embodiment 3 of the present invention. 3, the same components as those in FIGS. 1, 3, and 4 are denoted by the same reference numerals, and description thereof is omitted.

  In FIG. 3, the heat input temperature sensor 204 is provided between the outlet of the buffer tank 203 and the inlet of the heat exchanger 102 in the heat recovery pipe B 106 in order to detect the temperature of the heat recovery water entering the heat exchanger 102. . Further, the heat exchange temperature sensor 108 is installed at a position where the temperature of the heat recovery water flowing through the heat recovery pipe C107 between the outlet of the heat exchanger 102 and the switch 109 can be detected, and the temperature inside the hot water storage unit 202 of the heat recovery pipe C107. In order to detect the temperature of the heat recovery water until the inlet of the hot water storage tank 104, a hot water storage temperature sensor 205 is provided.

  According to such a configuration, if the amount of heat exhausted from the fuel cell 101 from the heat exchanger 102 is Q, the temperature detected by the heat input temperature sensor 204, which is the temperature at which heat recovery water enters the heat exchanger 102, is Ti, Assuming that the detected temperature of the heat exchange temperature sensor 108, which is the temperature after heating the exchanger 102, is To, M is the flow rate of the heat recovery water flowing through the circuit, and R is the rotational speed of the circulation pump 103, the temperature difference ΔToi = To− Q = ΔToi · M with respect to Ti, where the circulation flow rate M can be said to be proportional to the rotation speed R of the circulation pump 103 (M∝R). Therefore, the heat exchanger 102 is controlled by controlling the rotation speed of the circulation pump 103. The temperature To after heating can be controlled. When the rotational speed R is increased and the circulation flow rate M is increased, the temperature difference ΔToi is decreased. If the amount of heat released by the outside air is H, the temperature before heat release of the heat recovery water flowing through the heat recovery pipe C is the temperature detected by the heat exchange temperature sensor 108, and the temperature after heat release is the hot water storage temperature sensor. Assuming that the detected temperature 205 is Tt and the temperature difference ΔTot = To−Tt due to the temperature drop of the pipe, it can be said that the amount of heat release is approximately H≈ΔTot · M because it is mainly dependent on convection heat dissipation. Therefore, if the rotational speed R of the circulation pump 103 is increased from Tot≈H / M and the circulation flow rate M is increased, the temperature drop due to heat radiation can be reduced.

  As described above, the temperature of the heat exchange temperature sensor 108 is controlled by the number of rotations of the circulation pump 103 so that the heat recovery water temperature heated by the heat exchanger 102 becomes the hot water storage target temperature, and the heat exchange temperature sensor 108 and the hot water storage When it is determined that heat radiation is large from the temperature with the temperature sensor 205, the heat exchange temperature sensor 108 is circulated to reduce the control temperature of the heat exchange temperature sensor 108 from the hot water storage target temperature to the second target temperature in a range that does not hinder the operation of the fuel cell. The number of rotations of the pump 103 is increased, and the switch 109 is switched to the bypass circuit 110 when the temperature of the heat exchange temperature sensor 108 is lowered to the second target temperature. As a result, the temperature of the heat recovery water in the circulation circuit rises to the second target temperature. When the temperature of the heat input temperature sensor becomes high to the second target temperature, the control temperature of the heat exchange temperature sensor is changed to the hot water storage target temperature, and the rotation speed of the circulation pump 103 is controlled. However, the number of revolutions here is higher than the number of revolutions when it is determined that the heat radiation is large because the circulating temperature is rising. Therefore, the amount of heat radiation can be reduced by increasing the circulation flow rate flowing through the heat recovery pipe C107 and the heat recovery pipe A105, and as a result, hot water can be stored in the hot water storage tank 104.

  Here, if controllable, the hot water storage temperature sensor 205 can be abolished and the temperature can be controlled by the temperature of the heat exchange temperature sensor 108. Further, when the function of detecting the temperature after heating of the heat exchanger 102 of the heat exchange temperature sensor 108 and the function of detecting the switching temperature of the switch 109 cannot be realized at the same time, the temperature sensor after the heat exchanger 102 and before the switch 109 respectively. May be installed.

  The hot water storage type exhaust heat recovery system according to the present invention is a system that effectively uses exhaust heat of a fuel cell or the like, and a main body unit that generates the exhaust heat and a hot water storage unit are separated and exhausted between them using a heat recovery pipe. It is useful as a system that can reduce a heat dissipation loss that occurs between outside air and heat recovery piping in a system that transports heat.

102 Heat Exchanger 103 Circulation Pump 104 Hot Water Storage Tank 105 Heat Recovery Pipe A
106 Heat recovery pipe B
107 Heat recovery piping C
108 Heat Exchange Temperature Sensor 109 Switch 110 Bypass Pipe 201 Fuel Cell Unit 202 Hot Water Storage Unit 203 Buffer Tank 204 Heat Exchange Temperature Sensor 205 Hot Water Storage Temperature Sensor

Claims (3)

A fuel cell unit, which is a device having a heat exchanger for exchanging exhaust heat with heat recovery water, and hot water storage for storing the recovered heat of the fuel cell for use as hot water A hot water storage unit having a tank, a circulation pump that circulates heat recovery water in the fuel cell unit, and a heat recovery pipe that sends the water in the hot water storage tank as heat recovery water from the bottom connection port in the hot water storage tank in the hot water storage unit to the circulation pump A, heat recovery pipe B for sending heat recovery water from the circulation pump to the heat exchanger of the fuel cell unit, and a hot water storage tank in the hot water storage unit for recovering the heat recovered from the heat exchanger of the fuel cell unit Switching to a circuit different from the route to the upper part of the hot water storage tank in the fuel cell unit in the middle of the heat recovery pipe C When, hot-water storage type heat recovery system including a bypass pipe passing through the fuel cell unit for combining the heat recovery pipe A in the circulation pump before the switch in the switched heat recovery water heat recovery pipe A. The hot water storage type exhaust heat recovery system according to claim 1, having a circuit configuration having a buffer tank in a path between a junction of the bypass pipe and the heat recovery pipe A and an inlet of the heat exchanger in the fuel cell unit. On the path between the heat exchanger temperature sensor that detects the temperature of the heat recovery water on the path between the outlet of the heat exchanger and the switch, and on the path between the inlet of the heat exchanger, the bypass pipe, and the heat recovery pipe A Heat exchange temperature sensor for detecting the temperature of the heat recovery water inlet of the heat recovery water, hot water storage temperature sensor for detecting the temperature of the heat recovery water from the heat recovery pipe A in the hot water storage unit to the hot water storage tank, and heat exchange A function that controls the temperature of the heat exchanging temperature sensor with the number of rotations of the circulating pump so that the temperature of the heat recovery water after heating in the cooler becomes the target temperature for hot water storage, and the switch stores hot recovered water in the hot water storage tank on the hot water storage tank side. When it is judged that the heat dissipation is large from the temperature information of the heat exchange temperature sensor and the hot water storage temperature sensor, the control temperature of the heat exchange temperature sensor is set from the hot water storage target temperature to the fuel cell operation. The second target temperature in the range and the heat exchange temperature When the temperature of the sensor decreases to the second target temperature, the switch is switched to a bypass circuit, and when the temperature of the heat input temperature sensor reaches the second target temperature, the control temperature of the heat exchange temperature sensor is stored. The hot water storage type exhaust heat according to claim 1 or 2, further comprising a control function of switching to a hot water storage tank side when the temperature of the heat exchange temperature sensor becomes higher than the switching set temperature when the temperature is changed to a target temperature. Collection system.

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