JP2012052686A - Fuel cell cogeneration system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell cogeneration system having high reliability, by securing safety with a simple structure.SOLUTION: The fuel cell cogeneration system includes a heat recovery passage 8 for sequentially and annularly connecting a heat exchanger 4 for heat recovery, which recovers waste heat during power generation of a fuel cell 7, with a hot water storage tank 1 by heat recovery piping 3. The heat recovery piping 3 is provided with a pressure relief valve 18 for the heat recovery passage, which is configured to open when the pressure in the heat recovery piping 3 exceeds a predetermined pressure. Thereby, the safety is secured and the fuel cell cogeneration system with high reliability is obtained.

Description

  The present invention relates to a fuel cell cogeneration system that recovers and uses exhaust heat of a fuel cell to generate hot water.

  In recent years, fuel cells that generate electrical energy by direct reaction of hydrogen and oxygen are expected to be clean power generators because they have high power generation efficiency and emit almost no air pollutants. In particular, a fuel cell cogeneration system that collects and uses exhaust heat generated during power generation of a fuel cell has high overall energy efficiency and is expected to spread as an energy saving device. As a method for recovering and utilizing the exhaust heat of the fuel cell, it is common to use the heat exchanger for heat recovery to heat the water in the hot water storage tank and use it as hot water.

  As shown in FIG. 3, the conventional fuel cell cogeneration system includes, for example, a fuel cell unit 21 that houses the fuel cell 7 and the heat exchanger 4 for heat recovery, and a hot water storage unit 22 that houses the hot water storage tank 1. (For example, see Patent Document 1).

  Further, as shown in FIG. 3, the heat recovery path 8 is formed by sequentially connecting the hot water storage tank 1, the hot water circulation pump 2, and the heat recovery heat exchanger 4 in an annular manner through the heat recovery pipe 3. Yes. On the other hand, the cooling water passage 20 is formed by sequentially connecting the fuel cell 7, the cooling water circulation pump 5, and the heat recovery heat exchanger 4 in an annular manner through the cooling water pipe 6.

  And the waste heat which generate | occur | produces when the fuel cell 7 generates electric power etc. is collect | recovered by cooling water. The cooling water is conveyed to the heat recovery heat exchanger 4 by the cooling water circulation pump 5, where water from the hot water storage tank 1 is heated. At this time, the water in the hot water storage tank 1 circulates in the heat recovery path 8 by the hot water storage circulation pump 2, is heated by the cooling water of the fuel cell 7 in the heat recovery heat exchanger 4, and is stored in the hot water storage tank 1 again. It is done.

  The fuel cell cogeneration system also includes a water supply inlet pipe 9, a pressure reducing valve 10, a first water supply pipe 11 and a second water supply pipe 12, in order to supply water to the hot water storage tank 1 and to supply hot water from the hot water storage tank 1 to the outside. A hot water discharge pipe 13, a mixing valve 14, and a hot water supply outlet pipe 15 are provided.

  Water supply to the hot water storage tank 1 is performed via a pressure reducing valve 10 and a first water supply pipe 11 from a water supply inlet pipe 9 connected to a general water supply pipe. Hot water from the hot water storage tank 1 was discharged from the water supplied via the water supply inlet pipe 9, the pressure reducing valve 10, and the second water supply pipe 12 and from the upper part of the hot water storage tank 1 via the hot water discharge pipe 13. Hot water is mixed at an appropriate temperature by the mixing valve 14 and supplied to the outside through the hot water supply outlet pipe 15.

  In the fuel cell cogeneration system configured as described above, a hot water tank pressure relief valve 19 is generally installed so as to communicate with the hot water tank 1.

  According to Patent Document 1, water stored in the hot water storage tank 1 having a hermetically sealed structure is heated by the exhaust heat of the fuel cell 7 and expands. The internal pressure of the hot water storage tank 1 rises due to thermal expansion. Accordingly, when the hot water tank pressure relief valve 19 is opened at a predetermined pressure, a part of the expanded water is opened to the outside. As a result, the pressure increase in the hot water storage tank 1 is suppressed, and the hot water storage tank 1 can be protected.

JP 2002-280031 A

  However, in the above conventional configuration, when the hot water tank pressure relief valve 19 fails due to sticking or the like, the hot water storage tank 1, the heat recovery path 8, the first water supply pipe 11, the second water supply pipe 12, and the hot water discharge pipe 13 are Since this is a closed space, the inside of the fuel cell 7 becomes abnormally high pressure due to the expansion of water as the fuel cell 7 is operated. As a result, there has been a problem that parts such as the hot water storage tank 1 and pipes, pumps, and heat exchangers in each path are damaged.

  The present invention solves the above-described conventional problems, and has a simple structure, avoids problems caused by failure of a pressure relief valve for a hot water storage tank, ensures safety, and has a highly reliable fuel cell cogeneration system. The purpose is to provide.

  In order to solve the above-described conventional problems, the fuel cell cogeneration system of the present invention is a heat recovery heat exchanger that recovers exhaust heat from a fuel cell and a hot water storage tank that are sequentially connected in an annular shape by a heat recovery pipe. A fuel cell cogeneration system including a recovery path, wherein the heat recovery pipe includes a heat recovery path pressure relief valve that opens when a pressure in the heat recovery pipe exceeds a predetermined pressure.

  Thereby, even when the pressure relief valve for the hot water storage tank fails due to sticking or the like, the heat recovery path can be opened with a predetermined pressure. Therefore, it is possible to suppress an increase in pressure in the hot water storage tank, the heat recovery path, and the cooling water path during operation of the fuel cell. As a result, it is possible to realize a highly reliable fuel cell cogeneration system that ensures safety and can prevent damage to parts such as hot water storage tanks, piping in each path, pumps, heat exchangers, and the like.

  According to the present invention, a fuel cell cogeneration system with improved safety and reliability can be realized with a simple configuration.

1 is a configuration diagram of a fuel cell cogeneration system according to Embodiment 1 of the present invention. Configuration diagram of fuel cell cogeneration system in Embodiment 2 of the present invention Configuration diagram of conventional fuel cell cogeneration system

  A first invention is a fuel cell cogeneration system including a heat recovery path in which a heat recovery heat exchanger for recovering exhaust heat of a fuel cell and a hot water storage tank are sequentially connected in an annular manner by a heat recovery pipe, The heat recovery pipe has a configuration in which a heat recovery path pressure relief valve that opens when the pressure in the heat recovery pipe exceeds a predetermined pressure is provided. Thereby, even when the pressure relief valve for the hot water storage tank fails due to sticking or the like, the heat recovery path can be opened with a predetermined pressure. Therefore, it is possible to suppress an increase in pressure in the hot water storage tank, the heat recovery path, and the cooling water path during operation of the fuel cell. As a result, it is possible to realize a highly reliable fuel cell cogeneration system that ensures safety and can prevent damage to parts such as hot water storage tanks, piping in each path, pumps, heat exchangers, and the like.

  According to a second invention, in the first invention, a hot water storage tank pressure relief valve is provided that opens when the pressure in the hot water storage tank exceeds a predetermined pressure, and the predetermined pressure at which the heat recovery path pressure relief valve opens is stored. The pressure was higher than the predetermined pressure at which the tank pressure relief valve opened. Thereby, even if the pressure relief valve for the hot water storage tank breaks down, the pressure relief valve for the heat recovery path acts as a double safety device, and an abnormal pressure increase can be avoided. Furthermore, during normal fuel cell operation, the pressure relief valve for the hot water storage tank is opened and the thermally expanded water is allowed to escape to the outside without causing fluctuations in the flow rate of the hot water circulating in the heat recovery path. Stable operation of the battery cogeneration system can be realized.

  According to a third aspect, in the first or second aspect, the pressure recovery valve for the heat recovery path is configured to function also as a drain plug for discharging water in the heat recovery path. As a result, drainage during maintenance and pressure relief generated by the expansion of the hot water storage can be realized with a very simple configuration.

  In a fourth aspect based on the third aspect, the heat recovery path pressure relief valve is provided in a relatively low region of the heat recovery pipe on the upstream side of the heat recovery heat exchanger. Thereby, water can be easily drained from the heat recovery pipe and the heat exchanger for heat recovery by utilizing the weight of water during maintenance.

  According to a fifth invention, in the first or second invention, the heat recovery path pressure relief valve is configured to function also as an air vent plug for discharging air in the heat recovery path. Accordingly, it is possible to realize air venting generated during the heating of water and pressure relief generated due to the expansion of the hot water storage with an extremely simple configuration.

  In a sixth aspect based on the fifth aspect, the heat recovery path pressure relief valve is provided in a relatively high region of the heat recovery pipe on the downstream side of the heat recovery heat exchanger. Thereby, the air recovery of the heat recovery pipe and the heat recovery heat exchanger can be easily performed by utilizing the fact that the density of the air generated when heating the water is small.

  According to a seventh invention, in the first invention, the fuel cell unit includes a fuel cell unit that stores a fuel cell and a heat recovery heat exchanger, and a hot water storage unit that stores a hot water storage tank. It arrange | positions at the heat recovery piping which connects a battery unit and a hot water storage unit. Thereby, the water and air which flow out when the pressure in the heat recovery pipe is released can be easily released to the outside of each unit, and unnecessary water can be prevented from being stored.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the same reference numerals are given to the same configurations as the conventional configurations described above, and the detailed description thereof will be omitted. The present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a configuration diagram of a fuel cell cogeneration system according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the fuel cell cogeneration system of the present embodiment includes a fuel cell unit 21 that houses a fuel cell 7 and a heat exchanger 4 for heat recovery, and a hot water storage unit 22 that houses a hot water storage tank 1. The heat recovery pipe 3 for connecting the fuel cell unit 21 and the hot water storage unit 22 is provided with a heat recovery path pressure relief valve 18.

Then, a hot water storage tank 1, a hot water circulation pump 2, and a heat recovery heat exchanger 4 that recovers exhaust heat during power generation of the fuel cell 7 are sequentially connected in an annular manner by a heat recovery pipe 3, and a heat recovery path 8 is formed. In addition, the cooling water passage 20 is formed by sequentially connecting the fuel cell 7, the cooling water circulation pump 5, and the heat recovery heat exchanger 4 in an annular manner through the cooling water pipe 6.

  The exhaust heat generated during the power generation of the fuel cell 7 is recovered in the cooling water in the cooling water passage 20, and is transferred to the heat recovery heat exchanger 4 by the cooling water circulation pump 5, and the water from the hot water storage tank 1. Heat. The water in the hot water storage tank 1 is circulated through the heat recovery path 8 by the hot water storage circulation pump 2 and heated by the cooling water or the like that has absorbed the exhaust heat of the fuel cell 7 by the heat recovery heat exchanger 4. Stored in tank 1.

  Further, the heat recovery pipe 3 is provided with a heat recovery path pressure relief valve 18 which opens when the pressure of the heat recovery pipe 3 exceeds a predetermined pressure and holds the pressure in the heat recovery pipe 3 below a predetermined pressure. ing. Further, the hot water storage tank 1 is connected to a hot water storage tank pressure relief valve 19 which opens when the pressure in the hot water storage tank 1 exceeds a predetermined pressure and holds the pressure in the hot water storage tank 1 below a predetermined pressure. .

  At this time, the predetermined pressure at which the heat recovery path pressure relief valve 18 opens is set higher than the predetermined pressure at which the hot water tank pressure relief valve 19 opens.

  Further, the heat recovery path pressure relief valve 18 may have a function that can also be used as a drain plug for discharging water in the heat recovery path 8.

  The heat recovery path pressure relief valve 18 and the hot water storage tank pressure relief valve 19 having these functions have, for example, a hollow cylinder shape with both ends open, and the valve body is biased by a spring force therein. It is preferable to use a structure. At this time, when the internal pressure rises, the valve body automatically moves against the spring force, thereby opening a part of the heat recovery path 8 and releasing the internal pressure to the outside through the cylinder. At this time, as will be described below, the outer periphery of the heat recovery path pressure relief valve 18 may be formed into a screwable shape, for example, so that a part of the heat recovery path 8 can be manually opened. Thus, the heat recovery path pressure relief valve 18 can be removed and used as a drain plug for draining the heat recovery pipe 3.

  When the heat recovery path pressure relief valve 18 is used as a drain plug, as shown in FIG. 1, on the upstream side of the heat recovery heat exchanger 4, the heat recovery pipe 3 has a relatively low region 18 </ b> A. It is desirable to provide it. For example, the heat recovery pipe 3 outside the fuel cell unit 21 is directly provided in a pipe joint (not shown) for connecting to the fuel cell unit 21, or the heat recovery heat exchanger 4 inside the pipe joint and the fuel cell unit 21. May be provided at the lowermost part of the pipe connecting the two. Here, the relatively low region 18A is a region below the heat recovery pipe 3 between the hot water storage tank 1 and the hot water circulation pump 2 in a state where the hot water storage unit 22 and the fuel cell unit 21 are stationary. At this time, it is preferable to provide the pressure relief valve 18 for heat recovery path at the lowermost part of the relatively low region 18A.

  If the water circulating through the heat recovery pipe 3 in the relatively low region 18A does not become full by draining with the pressure relief valve 18 for the heat recovery path, it is not particularly necessary to provide it at the lowermost part. Thereby, since the water inside the heat recovery path 8, in particular, the heat exchanger for heat recovery 4 falls due to its own weight, the amount of water remaining inside can be reduced as much as possible. Further, particularly when the fuel cell cogeneration system is used in a cold region, the heat recovery pipe 3 can be prevented from being damaged due to water freezing.

  In addition, the fuel cell cogeneration system of the present embodiment includes a water supply inlet pipe 9, a pressure reducing valve 10, a first water supply pipe 11 and a first water supply pipe for supplying water to the hot water storage tank 1 and supplying hot water from the hot water storage tank 1 to the outside. 2 A water supply pipe 12, a hot water discharge pipe 13, a mixing valve 14 and a hot water supply outlet pipe 15 are provided.

  Water supply to the hot water storage tank 1 is performed via a pressure reducing valve 10 and a first water supply pipe 11 from a water supply inlet pipe 9 connected to a general water supply pipe. Hot water from the hot water storage tank 1 was discharged from the water supplied via the water supply inlet pipe 9, the pressure reducing valve 10, and the second water supply pipe 12 and from the upper part of the hot water storage tank 1 via the hot water discharge pipe 13. Hot water is mixed at an appropriate temperature by the mixing valve 14 and supplied to the outside through the hot water supply outlet pipe 15.

  Also in the present embodiment, a hot water tank pressure relief valve 19 is provided so as to communicate with the hot water tank 1 as in the prior art. And the internal pressure which rose when the water in the hot water storage tank 1 which has a sealing structure is heated and expanded by the exhaust heat of the fuel cell 7 is opened when the hot water tank pressure relief valve 19 opens at a predetermined pressure. . Thereby, a part of the expanded water can be opened to the outside, the pressure increase in the hot water storage tank 1 can be suppressed, and the hot water storage tank 1 can be protected.

  According to the fuel cell cogeneration system of the present embodiment, even if the hot water tank pressure relief valve 19 fails due to sticking or the like, the heat recovery path pressure relief valve 18 opens at a predetermined pressure, and the heat recovery path 8 is released. Therefore, when the fuel cell 7 is operated, an increase in pressure in the hot water storage tank 1, the heat recovery path 8, and the cooling water path 20 can be suppressed. As a result, it is possible to prevent damage to parts such as the hot water storage tank 1 and pipes, pumps, and heat exchangers in each path.

  Further, according to the fuel cell cogeneration system of the present embodiment, the predetermined pressure at which the heat recovery path pressure relief valve 18 opens is set higher than the predetermined pressure at which the hot water tank pressure relief valve 19 opens. As a result, even if the hot water tank pressure relief valve 19 fails, the heat recovery path pressure relief valve 18 can act as a double safety device to avoid an abnormal pressure rise in the hot water tank 1. In addition, during normal operation of the fuel cell 7, the hot water storage tank pressure relief valve 19 is opened to allow the thermally expanded water to escape to the outside, thereby causing fluctuations in the flow rate of the hot water circulating in the heat recovery path 8. Without this, stable operation of the fuel cell cogeneration system can be realized.

  Further, according to the fuel cell cogeneration system of the present embodiment, the heat recovery path pressure relief valve 18 has a function as a drain plug for discharging water in the heat recovery path 8. Thereby, drainage at the time of maintenance and pressure relief generated by expansion of the hot water storage can be performed with a very simple configuration.

  Further, a heat recovery path pressure relief valve 18 is provided in a relatively low region 18 </ b> A of the heat recovery pipe 3 on the upstream side of the heat recovery heat exchanger 4. Thereby, water can be easily drained from the heat recovery pipe 3 and the heat recovery heat exchanger 4 by the weight of water during maintenance.

  Further, according to the fuel cell cogeneration system of the present embodiment, the heat recovery path pressure relief valve 18 is arranged in the heat recovery pipe 3 connecting the fuel cell unit 21 and the hot water storage unit 22. Thereby, it is possible to prevent water and air flowing out when the inside of the heat recovery pipe 3 is opened at a predetermined pressure to the outside of the fuel cell unit 21 and the hot water storage unit 22 and to store unnecessary water.

  As described above, according to the present embodiment, it is possible to provide a highly reliable fuel cell cogeneration system that ensures safety with a simple configuration.

(Embodiment 2)
FIG. 2 is a configuration diagram of a fuel cell cogeneration system according to Embodiment 2 of the present invention.

  As shown in FIG. 2, the fuel cell cogeneration system of the present embodiment is configured such that the heat recovery path pressure relief valve 18 functions as an air vent plug for discharging the air in the heat recovery path 8. Thus, it is different from the first embodiment. The configuration and operation of the fuel cell cogeneration system according to the present embodiment are substantially the same as those described in the first embodiment, and thus detailed description thereof is omitted here.

  That is, as shown in FIG. 2, the fuel cell cogeneration system of the present embodiment includes a fuel cell unit 21 that houses the fuel cell 7 and the heat exchanger 4 for heat recovery, and a hot water storage unit 22 that houses the hot water storage tank 1. The heat recovery pipe 3 for connecting the fuel cell unit 21 and the hot water storage unit 22 is provided with a pressure recovery valve 18 for the heat recovery path. At this time, the heat recovery path pressure relief valve 18 is provided in a relatively high region 18B of the heat recovery pipe 3 on the downstream side of the heat recovery heat exchanger 4. Specifically, for example, the heat recovery path pressure relief valve 18 is arranged in the fuel cell unit 21 so that the water sent from the hot water storage tank 1 flows from the bottom to the top in the vertical direction. It is provided in the vicinity of the pipe connected to the outlet of the vessel 4. Here, the relatively high region 18B is a region above the heat recovery pipe 3 between the hot water storage tank 1 and the heat recovery heat exchanger 4 in a state where the hot water storage unit 22 and the fuel cell unit 21 are stationary. . At this time, it is preferable to provide the pressure relief valve 18 for the heat recovery path at the top of the relatively high region 18B, but it is not necessary to provide it at the top as long as it is within the relatively high region 18B. Thereby, the function as an air vent plug which discharges | emits the air in the heat recovery path | route 8 can be provided.

  As in the first embodiment, the heat recovery path pressure relief valve 18 having these functions has, for example, a hollow cylinder shape with both ends open, and a structure in which the valve body is biased by a spring force therein. It is preferable to use those. At this time, when the internal pressure rises, the valve body automatically moves against the spring force, thereby opening a part of the heat recovery path 8 and releasing the internal pressure to the outside through the cylinder.

  The effect of using the heat recovery path pressure relief valve 18 as an air vent plug will be described below.

  Usually, some air is dissolved in the relatively low temperature water sent from the hot water storage tank 1. Therefore, when this water is heated by the heat recovery heat exchanger 4, dissolved air may be generated as fine bubbles. The air remaining in the heat recovery path 8 may obstruct the flow of water or may adhere to the heat transfer surface of the heat recovery heat exchanger 4 to deteriorate the heat exchange performance. Then, the said subject can be eliminated by using the pressure relief valve 18 for heat recovery paths as an air vent plug.

  According to the fuel cell cogeneration system of the present embodiment, the discharge of air generated when water is heated and the pressure relief when maintenance is abnormal can be realized with a very simple configuration. Further, by disposing the pressure relief valve 18 for the heat recovery path at a high position of the heat recovery pipe, the heat recovery pipe 3 and the heat recovery heat exchanger 4 can be easily vented. This is because the air generated during the heating of water has a density lower than that of water, and therefore rises in the heat recovery pipe and tends to accumulate upward. As a result, a highly reliable fuel cell cogeneration system can be provided.

In the above-described embodiment, the heat recovery path pressure relief valve 18 has been described as being configured and used as a drain plug or an air drain plug, but is not limited thereto. For example, it may be used simply as the pressure recovery valve 18 for the heat recovery path. In that case, if the heat recovery path pressure relief valve 18 is the heat recovery path 8, it may be provided at any position within the fuel cell unit 21, the hot water storage unit 22, or the heat recovery pipe 3 connecting them. I do not care.

  In each embodiment, the heat recovery heat exchanger 4 has been described as an example of recovering the exhaust heat of the fuel cell 7, but the present invention is not limited to this. For example, the exhaust heat of exhaust gas from a hydrogen production apparatus (not shown) provided in the fuel cell cogeneration system and the exhaust heat of the anode and cathode of the fuel cell 7 may be recovered.

  INDUSTRIAL APPLICABILITY The present invention is useful in technical fields such as a fuel cell cogeneration system in which safety is ensured with a simple configuration and high reliability is required.

DESCRIPTION OF SYMBOLS 1 Hot water storage tank 2 Hot water storage circulation pump 3 Heat recovery piping 4 Heat exchanger for heat recovery 5 Cooling water circulation pump 6 Cooling water piping 7 Fuel cell 8 Heat recovery path 9 Feed water inlet pipe 10 Pressure reducing valve 11 First feed pipe 12 Second feed pipe 13 Hot water outlet pipe 14 Mixing valve 15 Hot water supply outlet pipe 18 Pressure relief valve for heat recovery path 18A, 18B area 19 Pressure relief valve for hot water storage tank 20 Cooling water path 21 Fuel cell unit 22 Hot water storage unit

Claims (7)

A fuel cell cogeneration system having a heat recovery path in which a heat recovery heat exchanger for recovering exhaust heat of a fuel cell and a hot water storage tank are sequentially connected in an annular manner by a heat recovery pipe,
A fuel cell cogeneration system provided with a pressure relief valve for a heat recovery path that opens when the pressure in the heat recovery pipe exceeds a predetermined pressure in the heat recovery pipe. A hot water storage tank pressure relief valve that opens when the pressure in the hot water tank exceeds a predetermined pressure;
2. The fuel cell cogeneration system according to claim 1, wherein a predetermined pressure at which the heat recovery path pressure relief valve is opened is higher than a predetermined pressure at which the hot water tank pressure relief valve is opened. The fuel cell cogeneration system according to claim 1 or 2, wherein the heat recovery path pressure relief valve functions also as a drain plug for discharging water in the heat recovery path. 4. The fuel cell cogeneration system according to claim 3, wherein the heat recovery path pressure relief valve is provided in a relatively low region of the heat recovery pipe upstream of the heat recovery heat exchanger. The fuel cell cogeneration system according to claim 1 or 2, wherein the pressure relief valve for the heat recovery path is configured to function also as an air vent plug for discharging air in the heat recovery path. 6. The fuel cell cogeneration system according to claim 5, wherein the heat recovery path pressure relief valve is provided in a relatively high region of the heat recovery pipe on the downstream side of the heat recovery heat exchanger. A fuel cell unit housing the fuel cell and the heat recovery heat exchanger;
A hot water storage unit for storing the hot water storage tank,
2. The fuel cell cogeneration system according to claim 1, wherein the heat recovery path pressure relief valve is disposed in the heat recovery pipe connecting the fuel cell unit and the hot water storage unit.

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