JP2006073416A - Absorption-type refrigerator composite fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a more economical fuel cell system by effectively utilizing exhaust heat or exhaust energy exhausted from a fuel cell stack. <P>SOLUTION: The fuel cell system 10 is formed, by combining an SOFC unit 100 and an absorption type refrigerator 500 equipped with a regenerator 54. Fuel electrode exhaust gas which is the exhaust energy exhausted from a fuel cell stack 110 of the SOFC unit 100 and air electrode exhaust air are burned in a combustion chamber 124, and the regenerator 54 of the absorption-type refrigerator 500 is exteriorly heated with combustion exhaust gas EG. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system that utilizes exhaust energy such as high-temperature combustion exhaust gas or fuel electrode exhaust gas and air electrode exhaust gas discharged from a fuel cell unit with an absorption refrigeration machine, and more particularly to a housing complex. In a system in which fuel supply such as reformed gas is supplied from a centralized fuel gas supply facility to fuel cell units distributed and installed as residential and commercial power generation facilities for home and business use, The present invention relates to an absorption refrigeration combined fuel cell system capable of suitably utilizing waste heat.

  In recent years, fuel cell systems such as polymer electrolyte fuel cells (PEFC) and solid oxide fuel cells (SOFC) are being introduced as power and heat supply systems for homes and businesses. Such a fuel cell system is a system that generates electricity and hot water using city gas, LPG, kerosene, or the like as fuel, and the generated electricity is used as electric power for electric equipment. Moreover, hot water generated using the exhaust heat of the fuel cell is stored in a hot water storage tank and supplied to an oil supply system in a consumer. Thus, the fuel cell system has a function of supplying both electricity and heat by a single unit. Currently, models with power generation capacities of 500 W to 1 kW for household fuel cells and 3 to 5 kW and 30 kW class power generation capacities for commercial fuel cells are being developed.

  FIG. 12 is a block diagram showing a configuration example of a PEFC system 800 that is expected as a household or commercial fuel cell. This system 800 generally introduces a fuel gas G such as city gas into the reformer 810 to purify the reformed gas and send it to the PEFC battery stack 830 to perform a power generation operation as well as an exhaust heat recovery unit. At 850, low-temperature water is taken out. More specifically, the odorant contained in the fuel gas G is first removed by the desulfurizer 801, the fuel gas G is preheated by the heat exchanger 802, mixed with the steam S, and then sent to the reformer 810. be introduced. The reformer 810 is heated by the burner 810a and is maintained at about 800 ° C., and the fuel gas G is converted into a reformed gas containing hydrogen as a main component by the action of the catalyst. This reformed gas is guided to the carbon monoxide converter 822 by lowering the temperature in the heat exchanger 821, and the carbon monoxide component contained in the gas is converted into hydrogen and carbon dioxide, followed by carbon monoxide selection. In the oxidizer 823, the residual carbon monoxide concentration in the gas is reduced to about 10 ppm. Thereafter, the reformed gas is introduced into the fuel electrode 831 of the battery stack 830 through the humidifier 824. The hydrogen component is ionized in the fuel electrode 831, passes through the electrolyte 833, and generates a chemical reaction with oxygen in the air electrode 832 by the air blower 835 to generate electric power and generate water.

  The electric power generated in the battery stack 830 is converted from direct current DC to alternating current AC by the inverter 840 and supplied to home and commercial power equipment. On the other hand, the battery stack 830 generates heat due to a chemical reaction between hydrogen and oxygen, but this heat (exhaust heat) is taken out by the exhaust heat recovery unit 850 to generate low-temperature water. That is, the battery cooling water CW3 is circulated through the circulation system including the radiator 851 and the pump 852 to the battery cooling plate 834 provided in the battery stack 830, and the battery stack 830 is maintained at a constant temperature of about 80 ° C. and heated. Is taken out. The heated battery cooling water CW3 exchanges heat with tap water in the heat exchanger 853 and is cooled to about 30 to 40 ° C., whereby low temperature water of about 60 ° C. is obtained. This hot water is stored in a hot water tank 854, and is used for hot water supply to a kitchen, a washroom, and a bath as needed.

  In addition to this, the fuel electrode exhaust gas G1 discharged from the fuel electrode 831 of the battery stack 830 and the air electrode exhaust air A1 discharged from the air electrode 832 are guided to the reformer burner 810a and burned to be reformed. It is used as a heat source. Thus, in the PEFC system 800, the generation of low-temperature water using the exhaust heat of the battery stack 830 and the utilization of the fuel electrode exhaust gas G1 and the air electrode exhaust air A1 as the heat source of the reformer 810 High efficiency is achieved.

  FIG. 13 is a block diagram illustrating a configuration example of an SOFC system 900 that is a representative of a high-temperature fuel cell. Also in this system 900, the fuel gas G such as city gas is introduced into the reformer 910 via the desulfurizer 901 and the preheater 902, and the fuel gas G is reformed mainly containing hydrogen in the reformer 910. It is the same as the PEFC system 800 described above in that it is converted to a quality gas. However, since the SOFC battery stack 930 can also use a carbon monoxide component as a fuel, the reformed gas is introduced as it is into the fuel electrode 931 of the battery stack 930 maintained at about 700 to 1000 ° C. Most of the hydrogen component (and carbon monoxide component) in the introduced reformed gas reacts with oxygen ions sent from the air electrode 932 at the fuel electrode 931 to generate electricity. Air is introduced into the air electrode 932 from an air blower 935, and oxygen in the air is taken in and ionized. Such oxygen ions are transferred to the fuel electrode 931 through the electrolyte 933, and chemically react with the hydrogen component (and the carbon monoxide component) to generate electricity. The generated power is converted from direct current DC to alternating current AC by an inverter 940 and supplied to household and commercial power equipment.

  Generally, the hydrogen utilization rate at the fuel electrode 931 is 70 to 80%, and the remainder is discharged as surplus (fuel electrode exhaust gas). Further, the oxygen utilization rate in the air at the air electrode 932 is 50 to 60%, and the remainder is discharged as surplus (air electrode exhaust air). In order to utilize such surplus energy, the fuel electrode exhaust gas and the air electrode exhaust air are introduced into the combustion chamber 934 disposed on the outlet side of the battery stack 930 and burned. The heat generated by this combustion is used to keep the battery stack 310 warm, and is also sent to the burner unit 910a of the reformer 910 to be used as a heat source for the reforming reaction, and then is heated by the heat exchangers 951 and 952. To be recovered. That is, the high-temperature combustion exhaust gas EG generated by the combustion in the combustion chamber 934 generates steam or a high temperature of about 90 ° C. in the high-temperature water heat exchanger 951 from the combustion exhaust gas after heat retention for the battery stack and the reforming reaction. The water HW is produced in the low-temperature water heat exchanger 952 as low-temperature water LW of about 60 ° C., respectively. Such high-temperature water HW and low-temperature water LW are widely used for business use or hot water supply.

It is also known to use steam or high-temperature water produced by the above-described high-temperature water heat exchanger 951 as a heat source for the absorption chiller. For example, Patent Document 1 discloses a configuration in which the steam of battery cooling water is guided to a heat exchanger disposed in a regenerator provided in an absorption chiller, and heat is exchanged with an absorbing liquid in the regenerator.
Japanese Patent No. 338405

  As described above, the fuel cell system generates electricity and heat at the same time, and it is possible to increase the economy by effectively using both. However, regarding the utilization of the exhaust heat from the fuel cell, the exhaust heat may not be sufficiently utilized depending on a known system. In other words, the SOFC system 900 can generate steam or high-temperature water of about 90 ° C. using the exhaust heat as described above. It can be used. On the other hand, since the PEFC system 800 can produce only low-temperature water of about 60 ° C. as described above, there is a problem that it can be used only for hot water supply and has a relatively low utility value. In addition, even in a high temperature fuel cell such as the SOFC system 900, the exhaust heat temperature level discharged by a small one used for home use becomes low, and it becomes difficult to obtain steam, so the economic efficiency is lowered. There is a case.

  By the way, when the fuel cell system is individually installed in a small-sized consumer existing in a certain local area such as in each household of an apartment house, a multipurpose commercial building, or a factory facility, fluctuations in heat and power load of individual consumers are Since they are mixed, there are merits such as a reduction in the amount of seasonal fluctuation of the load and a reduction in the maximum / minimum power demand width. For this reason, when introducing a fuel cell system to such an application, relatively small fuel cell units that do not have a reformer are dispersed and installed in each consumer, and the reformed gas is a centralized type common to each consumer. It is desirable that the fuel cell system is a centralized reforming fuel cell system in which the reformed gas is supplied to the fuel cell units refined by the fuel reformed gas supply device and dispersedly arranged by gas piping.

  When such a reformer intensive fuel cell system is adopted, a problem of effective utilization of unused hydrogen gas discharged from the battery stack emerges as a new problem. That is, not all of the reformed gas supplied to each fuel cell unit is consumed in the battery stack, and about 20% of unused hydrogen gas (fuel electrode exhaust gas) is air from the fuel electrode of the battery stack. Low oxygen concentration air (air electrode exhaust air) having an oxygen concentration reduced to about ½ of the atmosphere is discharged from the pole. These can be used by being burned by the reformer burner 810a in the above-described general PEFC system 800, but such a utilization mode cannot be obtained if a reformer centralized configuration is adopted. . Furthermore, since the SOFC system 900 cannot be used to use a part of the high-temperature combustion exhaust gas EG discharged from the combustion chamber 934 as a heat source for reforming, it is possible to effectively use surplus exhaust heat corresponding to the heat source for reforming. It becomes a problem.

  Accordingly, an object of the present invention is to provide a more economical fuel cell system by effectively utilizing exhaust heat and energy exhausted from the battery stack, and in particular, an individual fuel cell system such as a reformer intensive fuel cell system. An object of the present invention is to provide a system that can efficiently use waste energy efficiently in a fuel cell system including a fuel cell unit that does not include a reformer.

  An absorption refrigeration combined fuel cell system according to claim 1 of the present invention is a composite of a fuel cell unit that generates electricity by introducing fuel gas into a cell stack, and an absorption refrigeration machine including a regenerator. The fuel cell system has a waste energy utilization mechanism for using the waste energy discharged from the battery stack of the fuel cell unit as a heating source for externally heating the regenerator of the absorption chiller. It is characterized by.

  According to this configuration, the regenerator included in the absorption chiller is externally heated by the exhaust energy utilization mechanism using the exhaust energy discharged from the battery stack (for example, the fuel electrode exhaust gas and the air electrode exhaust air). The regenerator is heated with a burner that burns and the regenerator is heated with the high-temperature combustion exhaust gas), so that steam is passed through the heat exchanger into the regenerator as in the method of Patent Document 1. Therefore, the utilization of exhaust heat can be improved compared to the method of circulating and heating internally. In other words, the regenerator is heated by the waste energy itself discharged from the battery stack, rather than using the steam or high temperature water that is generated by the waste heat of the battery stack. Even when a fuel cell unit that is difficult to generate is used, the combined heat absorption refrigerator can easily and effectively utilize the exhaust heat (exhaust energy).

  In the above configuration, the fuel cell unit is composed of a high-temperature fuel cell unit, and the exhaust energy utilization mechanism uses a high-temperature combustion exhaust gas discharged from the battery stack of the high-temperature fuel cell unit to It can be set as the structure heated directly (Claim 2). According to this configuration, in order to keep the battery stack of the high-temperature fuel cell unit warm, the high-temperature combustion exhaust gas discharged from the combustion chamber attached to the battery stack is guided to the regenerator of the absorption refrigeration machine. The regenerator is directly heated by the combustion exhaust gas.

  In the above configuration, the fuel cell unit includes a low temperature fuel cell unit, and the exhaust energy utilization mechanism absorbs the fuel electrode exhaust gas and the air electrode exhaust air discharged from the battery stack of the low temperature fuel cell unit. The regenerator of the refrigerator can be sent to a regenerator burner for heating and combusted (claim 3). According to this configuration, the fuel electrode exhaust gas and the air electrode exhaust air discharged from the battery stack are utilized as fuel for the regenerator burner provided in the regenerator of the absorption chiller.

  4. The fuel cell unit according to claim 1, wherein the fuel cell unit is distributed among a plurality of consumers existing in a predetermined local area. The fuel gas may be supplied from a centralized fuel gas supply facility that is connected to the gas supply system and collectively purifies the fuel gas serving as the drive source of the fuel cell. According to this configuration, the fuel cell units distributed in each consumer are not provided with the reformer, but the waste energy used in the reformer is combined. Effective use in absorption refrigerators.

  Further, in any one of claims 1 to 4, a bypass piping system is provided in a piping system for a fuel gas introduced into a battery stack, and the bypass piping system regenerates the regenerator of the absorption chiller. It is desirable that the apparatus is connected to the burner (claim 5). According to this configuration, the fuel gas (reformed gas) supplied via the bypass piping system in the case where only the exhaust energy discharged from the battery stack causes a shortage in the amount of heat generated by the regenerator. By operating the regenerator burner, the regenerator can be stably heated.

  Furthermore, in any one of Claims 1-5, the combustion pipe | tube which derives | leads-out the combustion exhaust gas after directly heating the regenerator of an absorption refrigerating machine, or the regenerator burner with which an absorption refrigerating machine is equipped, It is desirable to pass through a heat exchanger for recovering the low-temperature water exhaust heat from the exhaust gas (claim 6). According to this configuration, the exhaust heat after directly heating the regenerator of the absorption chiller or the residual heat of the exhaust gas of the regenerator burner can be recovered as low-temperature water without being discarded, and high heat recovery Rate can be achieved.

  In the above-described configuration, it is desirable to provide a water recovery device that recovers moisture contained in the combustion exhaust gas as drain water when recovering the low-temperature water exhaust heat from the combustion exhaust gas by the heat exchanger. Water is generated by the chemical reaction in the battery stack, and when the fuel electrode exhaust gas and air electrode exhaust air are burned by the regenerator burner, water vapor is also generated by combustion, and these moisture is absorbed by the absorption refrigerator. Although it mixes as a vapor | steam in combustion exhaust gas, many water | moisture contents can be collect | recovered as drain water by cooling combustion exhaust gas with the said heat exchanger. According to the structure of Claim 7, this drain water is collect | recovered by the water collection | recovery apparatus, and it becomes possible to construct | assemble the system which can utilize produced | generated water without waste.

  An absorption refrigeration combined fuel cell system according to claim 8 of the present invention includes a fuel gas supply facility that is connected to a commercial gas supply system and purifies a fuel gas serving as a drive source of the fuel cell, and a predetermined local area. A fuel cell system comprising fuel cell units distributed to a plurality of existing consumers and an absorption refrigeration unit having a regenerator, wherein the fuel gas supply facility supplies fuel to each consumer. The fuel cell unit is a centralized fuel gas supply facility common to each fuel cell unit capable of supplying gas, and the fuel cell unit is an individual fuel cell unit that generates power to be supplied to at least a power load in each consumer, The absorption refrigeration unit uses exhaust energy discharged from a battery included in the fuel cell system as a heating source for heating the regenerator of the absorption chiller. And having a discharge energy utilization mechanism for there.

  According to the system of claim 1, since the regenerator is heated by the exhaust energy itself discharged from the battery stack, even when a fuel cell unit that is difficult to generate steam or high-temperature water by exhaust heat is used. The exhaust heat (exhaust energy) can be easily and effectively utilized. Therefore, even when a low-temperature fuel cell unit that can only generate low-temperature water for hot water supply is adopted, the absorption chiller can be driven using exhaust heat, and effective exhaust heat utilization is achieved. It will be able to plan.

  According to the system of claim 2, in the high-temperature fuel cell unit, the high-temperature combustion exhaust gas discharged from the combustion chamber is guided to the regenerator of the absorption refrigeration machine, and the regenerator is directly heated by the high-temperature combustion exhaust gas. Since it is a structure, a waste energy utilization mechanism can be constructed | assembled only by attaching the piping path which guides high temperature combustion exhaust gas from a combustion chamber to a regenerator substantially, and exhaust heat can be utilized still more effectively by a simple structure.

  According to the system of claim 3, in the low-temperature fuel cell unit, the fuel electrode exhaust gas and the air electrode exhaust air discharged from the cell stack are utilized as the fuel for the regenerator burner provided in the regenerator of the absorption chiller. Because of this configuration, a waste energy utilization mechanism can be constructed simply by installing a pipe line that leads the fuel electrode exhaust gas and air electrode exhaust air from the discharge side of the battery stack to the regenerator burner. It can be used more effectively.

  According to the system of claim 4, the fuel cell units distributed in each consumer are not provided with the reformer, but the waste energy used in the reformer is combined. It will be used effectively in the absorption chiller that is being used. Therefore, even when a reformer-intensive fuel cell system is introduced that can be expected to have various benefits for a small group of consumers, the waste energy discharged from each fuel cell unit is individually combined. It is possible to further improve the economic efficiency of the system by utilizing the absorption refrigeration machine and supplying heat for heating and cooling in each consumer. Furthermore, when a centralized reformed gas supply device is used, sulfur content is not included in the reformed gas, so sulfur corrosion does not occur even if the exhaust gas temperature from the absorption refrigerator is reduced to about 80 ° C. As a result, the exhaust gas temperature can be reduced from the normal 130 ° C. to about 80 ° C., whereby the latent heat of the water vapor contained in the exhaust gas can be recovered and the heat recovery efficiency can be improved.

  According to the system of claim 5, since the regenerator burner can be operated with the fuel gas (reformed gas) supplied via the bypass piping system, the operating load of the absorption chiller is limited to the fuel cell power load. Thus, it becomes possible to select an operation load suitable for the cooling and heating demand.

  According to the system of claim 6, since the exhaust gas after directly heating the regenerator of the absorption chiller or the residual heat of the exhaust gas of the regenerator burner can be recovered as low-temperature water without being discarded, high heat A recovery rate can be achieved.

  According to the system of the seventh aspect, the steam contained in the combustion exhaust gas is recovered as drain water by the water recovery device, so that the generated water can be used without waste.

  According to the system of claim 8, even when a fuel cell system is used in which fuel gas is supplied to a plurality of consumer groups existing in a predetermined local area with a centralized fuel gas supply facility, Since the exhaust energy is effectively utilized by the absorption chiller combined with the individual fuel cell units, the fuel cell system can be constructed with extremely high economic efficiency.

  Hereinafter, embodiments of an absorption refrigeration combined fuel cell system according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments, and may be changed as appropriate. Can be implemented.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of a fuel cell system S10 according to the first embodiment of the present invention. The fuel cell system S10 has a system configuration in which a solid oxide fuel cell (SOFC) unit 100 as a high-temperature fuel cell unit and an absorption refrigerator 500 are combined. The fuel cell system S10 uses the waste energy discharged from the battery stack 110 of the SOFC unit 100 as a heat source for externally heating the regenerator 54 included in the absorption chiller 500. As a mechanism, a method of directly heating the regenerator of the absorption chiller 500 with high-temperature combustion exhaust gas discharged from the battery stack 110 (combustion chamber 124) is adopted. Hereinafter, the configuration of each part will be described in detail.

  The SOFC unit 100 includes a desulfurizer 101 that removes sulfur from a fuel gas G such as city gas, a SOFC battery stack 110, a reformer 120 that purifies reformed gas, a combustion chamber 124, an air preheater 130, a blower, and the like. The air supply device 140 including the inverter 160 and the like. The SOFC battery stack 110 includes a fuel electrode 121, an air electrode 122, and an electrolyte 123. Such an SOFC unit 100 is called an internal reforming type, and is actually a system in which a reforming catalyst is placed in a battery stack to simultaneously generate power while reforming the fuel, and is often used in small machines up to tens of kW class Yes.

  The desulfurizer 101 and the reformer 120 are connected by a main piping 102 as a piping system for sending desulfurized fuel gas, and a valve 102B is provided in the main piping 102. . Further, a bypass piping (bypass piping system) 103 is branched from the main piping 102, and the terminal end of the bypass piping 103 is connected to the regenerator burner 50 a of the absorption chiller 500. A valve 103 </ b> B is also provided at an intermediate portion of the bypass piping 103. With such a piping configuration, the fuel gas G is added with the steam S through the main piping 102 and introduced into the reformer 120, and is converted into a hydrogen-rich reformed gas by the reformer 120, and the SOFC battery stack. 110 is introduced into the fuel electrode 121 of 110, and is supplied to the regenerator burner 50a of the absorption refrigerating machine 500 through the bypass piping 103. The amount of fuel gas supplied to both is appropriately adjusted by opening / closing control and opening degree control of the valve 102B and valve 103B.

  Further, the air supply device 140 and the air electrode 122 of the SOFC battery stack 110 are connected by an air supply piping 141 that passes through an air preheater 130. The pipe 141 is connected to a branch pipe 142 having a valve 142B that reaches the regenerator burner 50a of the absorption chiller 500. With such a piping configuration, the air A taken in by the air supply device 140 is introduced into the air electrode 122 through the piping 141 while being heated by the air preheater 130, and the valve 142B is When it is in the open state, it is sent to the regenerator burner 50a.

  Further, the combustion chamber 124 is provided with a combustion exhaust gas pipe 150 for guiding the high temperature combustion exhaust gas EG burned in the combustion chamber 124 to the regenerator of the absorption chiller 500. The combustion exhaust gas pipe line 150 passes through the air preheater 130, and the heat held by the high temperature combustion exhaust gas EG is transferred to the air A flowing through the pipe line 141 passing through the air preheater 130 in the same manner. It is like that.

  In the SOFC unit 100 configured as described above, most of the hydrogen component (and carbon monoxide component) in the reformed gas introduced into the fuel electrode 121 is sent from the air electrode 122 in the fuel electrode 121. It reacts with the coming oxygen ions and generates electricity. As described above, air is introduced into the air electrode 122 from the air supply device 140, and oxygen in the air is taken in and ionized. Such oxygen ions move to the fuel electrode 121 through the electrolyte 123, and chemically react with the hydrogen component (and carbon monoxide component) to generate electricity. Since the electric power generated here is a direct current, the inverter 160 converts the direct current into an alternating current and then supplies it as a drive power to various electric power devices existing in the consumer.

  Generally, the hydrogen utilization rate at the fuel electrode 121 is 70 to 80%, and the remainder is discharged as surplus (fuel electrode exhaust gas). Further, the oxygen utilization rate in the air at the air electrode 122 is 50 to 60%, and the remainder is discharged as surplus (air electrode exhaust air). In order to utilize such surplus energy, the fuel electrode exhaust gas and the air electrode exhaust air are introduced into the combustion chamber 124 disposed on the outlet side of the SOFC battery stack 110 and burned. The heat generated by this combustion is exclusively used as a heat source for the SOFC battery stack 110 and a heat source for the internal reforming reaction, but the combustion exhaust gas EG has high thermal energy. At 150, the heat is recovered by being guided to the regenerator of the absorption refrigerator 500. Although not shown in the figure, the flue gas EG passes through the heat exchange device by providing a branch pipe line in the flue gas pipe line 150 or by deriving a separate flue gas pipe line from the combustion chamber 124. Thus, it is also possible to adopt a system configuration in which high-temperature water and / or low-temperature water is generated by the heat exchange device and supplied to the heat demand device in the consumer.

  FIG. 2 is a block diagram illustrating an example of the internal configuration of the absorption chiller 500. The absorption chiller 500 is a single-effect absorption chiller, and generally includes four containers: a condenser 51, an evaporator 52, an absorber 53, and a regenerator 54. These containers are cyclically connected by four pipes 551 to 554 to form a sealed circulation system.

  The condenser 51 condenses water vapor to generate water. The condenser 51 is connected to the regenerator 54 by a pipe 551 so that the water vapor can be circulated, and is connected to the evaporator 52 by a pipe 552 to circulate water. Is possible. Further, a pipe 561 for circulating cooling water CW2 for cooling and condensing the water vapor is disposed inside the condenser 51.

  The evaporator 52 is for generating cold heat by the vaporization action of water, and a heat transfer tube 52a through which the cooling water CW1 is circulated is disposed. Water sent from the condenser 51 through the pipe 552 is dropped into the heat transfer pipe 52a. Further, the evaporator 52 and the absorber 53 are connected by a pipe 553 so that the water vapor evaporated on the surface of the heat transfer tube 52 a can move from the evaporator 52 toward the absorber 53.

  The absorber 53 stores an absorption liquid such as a lithium bromide solution having a water absorption capacity in the container, and absorbs water vapor transferred from the evaporator 52. The absorber 53 is connected to the regenerator 54 by a pipe 554, and the concentrated absorbent (lithium bromide solution) stored in the regenerator 54 is dropped through the pipe 554. Yes. A reflux pipe 562 extends from the lower part of the absorber 53, and the end of the reflux pipe 562 is connected to the upper part of the regenerator 54, and the lithium bromide solution in the absorber 53 is refluxed to the regenerator 54. It is possible. Further, the pipe 561 for circulating the cooling water CW2 is also passed through the absorber 53.

  The regenerator 54 heats and separates the moisture absorbed in the lithium bromide solution and concentrates the lithium bromide solution. In order to perform such heat separation, a regenerator burner 50a for heating the regenerator 54 externally to heat the internal lithium bromide solution is provided. In addition to this, in this embodiment, the end portion of the combustion exhaust gas pipe 150 that guides the combustion exhaust gas EG from the combustion chamber 124 of the SOFC battery stack 110 is disposed in the vicinity of the regenerator 54, and the regenerator 54 is caused by the combustion exhaust gas EG. Heating is possible externally.

  The operation of the absorption chiller 500 configured as described above will be described. First, the condenser 51 made of a sealed container is brought into a vacuum state of about 6.5 mmHg (that is, the circulation system made up of the four containers is made into a vacuum state), and water (refrigerant water) in the condenser 51 is piped. The refrigerant water is sent to the evaporator 52 via 552, and the refrigerant water is dropped into the heat transfer pipe 52a piped inside the evaporator 52. Since the inside of the evaporator 52 is in a vacuum state, water droplets adhering to the surface of the heat transfer tube 52a evaporate at about 5 ° C. while taking heat of vaporization from the heat tube 52a. For this reason, the cooling water CW1 flowing through the heat transfer tube 52a is cooled, and cooling cold water (cooling water CW1) is produced.

  The evaporated water vapor is moved to the absorber 53 through the pipe 553 and absorbed by the lithium bromide solution stored in the container of the absorber 53. If absorption of such water vapor continues, the concentration of the lithium bromide solution becomes thin, and the water vapor absorption capacity decreases. Therefore, while the lithium bromide solution diluted in the reflux pipe 562 is refluxed to the regenerator 54, the concentrated lithium bromide solution is supplied dropwise to the absorber 53 from the regenerator 54 via the pipe 554. It has become.

  That is, in the regenerator 54, the refluxed low-concentration lithium bromide solution is heated by heat from the regenerator burner 50a or external heating of the regenerator 54 by the combustion exhaust gas EG and absorbed in the lithium bromide solution. Moisture is expelled. As a result, a lithium bromide solution concentrated again in the regenerator 54 can be obtained, and can be used again in the absorber 53. The water vapor expelled by the regenerator 54 is sent to the condenser 51 through the pipe 551, and is cooled and condensed by the cooling water CW2 flowing through the pipe 561 to become water. The condensed water collects in the lower part of the condenser 51, and this water is reused in the evaporator 52 through the pipe 552. In addition, since the cooling water CW2 in the exit side of the piping 561 turns into low temperature water about 40-60 degreeC, it is utilized for the hot water supply etc. in a consumer.

  According to the fuel cell system S10 configured as described above, the high-temperature combustion exhaust gas EG generated by the combustion reaction between the fuel electrode exhaust gas and the air electrode exhaust air in the combustion chamber 124 during the operation of the SOFC unit 100 is the combustion exhaust gas. The pipe 150 leads, for example, to the combustion chamber of the regenerator burner 50a included in the absorption refrigerator 500, and thereby the regenerator 54 is heated externally. The regenerator 54 receives this heat and expels moisture absorbed in the lithium bromide solution as described above. Accordingly, since the exhaust energy of the SOFC battery stack 110 is used as a heating source for the regenerator 54 necessary for operating the absorption chiller 500, the absorption chiller 500 can be operated extremely economically. .

  Further, when the amount of heating heat is insufficient with only the combustion exhaust gas EG, or when the absorption chiller 500 is operated regardless of the operating state of the SOFC unit 100, the heating of the regenerator 54 using the regenerator burner 50a. Is possible. In this case, the valve 103B provided in the bypass piping 103 is opened, and the desulfurized fuel gas G1 is supplied to the regenerator burner 50a. At the same time, the valve 142B provided in the pipe line 142 is opened, the air A is also supplied to the regenerator burner 50a, the air A and the fuel gas G1 are burned by the regenerator burner 50a, and the regenerator 54 is heated. . By providing such a bypass system, the regenerator 54 can be stably heated regardless of the operating state of the SOFC unit 100, and thus the absorption chiller 500 can also be stably operated. As a result, it is possible to cope with a case where the cooling capacity becomes larger than the fuel cell capacity, or a case where the demand for cooling heat becomes particularly large in summer. If the temperature of the combustion exhaust gas EG is too low to be used as the heat source of the absorption chiller 500, it is mixed with the combustion gas of the regenerator burner 50a and used as the heat source of the absorption chiller 500. Also good.

  By the way, when it is burned using city gas or petroleum fuel, it is necessary to discharge from the piping system so that the temperature of the combustion exhaust gas does not decrease to about 130 ° C. or lower. If the regenerator 54 is configured to be heated with combustion exhaust gas obtained by burning city gas, the combustion exhaust gas needs to be discharged from the absorption chiller 500 so as not to be about 130 ° C. or lower. This is because when the temperature is 100 ° C. or lower, sulfur components contained in city gas and petroleum-based fuels form water droplets along with moisture and adhere to the wall surface (condensation), and the flue pipes corrode at low temperature. .

  However, in the case of a fuel cell, the sulfur content is removed from the fuel such as city gas by the desulfurizer 101, and the problem of low temperature corrosion due to the sulfur content condensation does not occur. For this reason, the exit temperature of the combustion exhaust gas EG from the absorption refrigerator 500 can be lowered to about 80 ° C., and the exhaust heat can be effectively used easily. In particular, since the combustion exhaust gas of the fuel cell contains a considerable amount of water vapor generated inside the cell stack, the latent heat of water can be recovered and utilized by cooling to 100 ° C. or lower.

  FIG. 3 is a block diagram showing a configuration of the fuel cell system S11 according to the modified embodiment of the first embodiment in consideration of such circumstances. The fuel cell system S11 is different from the fuel cell system S10 described above in that a low-temperature water exhaust heat and an exhaust heat / water recovery unit 600 that recovers water from the combustion exhaust gas EG are added. Hereinafter, this difference will be described.

  The exhaust heat / water recovery unit 600 includes a low-temperature water heat exchanger 61, a generated water recovery tank (water recovery device) 62, a generated water pipe 641, a water circulation pipe 642 and a valve 63 connecting them. . Inside the low-temperature water heat exchanger 61, the combustion exhaust gas EG discharged from the absorption chiller 500 is guided by the combustion exhaust gas pipe 151, and the heat held by the combustion exhaust gas EG can be taken out. The generated water pipe 641 is attached to the lower part of the low-temperature water heat exchanger 61 and guides the water generated by the low-temperature water heat exchanger 61 to the generated water recovery tank 62. The water circulation pipe 642 circulates water (tap water and product water), and heat is transferred to the water from the combustion exhaust gas EG via the low-temperature water heat exchanger 61. Yes.

  In such a configuration, the 80 to 100 ° C. combustion exhaust gas EG discharged from the absorption chiller 500 (regenerator 54) is guided to the low-temperature water heat exchanger 61 by the combustion exhaust gas pipe 151, and inside the water circulation pipe 642. The low temperature water LW of about 40-60 degreeC is manufactured by performing heat exchange with the water which distribute | circulates. After such heat exchange, the combustion exhaust gas EG is exhausted through the combustion exhaust gas pipe 152. On the other hand, the produced low-temperature water LW is appropriately supplied to the hot water supply facility of the customer via the valve 63. Therefore, according to the fuel cell system S11, the remaining heat can be recovered and effectively used from the combustion exhaust gas EG discharged from the absorption chiller 500, so that a more efficient fuel cell system can be obtained. In the fuel cell system S11, the air preheater 130 is placed between the absorption refrigerator 500 and the low-temperature water heat exchanger 61 according to the exhaust heat temperature of the combustion exhaust gas EG discharged from the SOFC battery stack 110. You may make it install.

  Further, the fuel cell system S11 also has a function of recovering moisture contained in the combustion exhaust gas EG in the generated water recovery tank 62. In general, water generated in the fuel cell stack is mixed with fuel electrode exhaust gas or air electrode exhaust air and discharged from the cell stack. In the case of a system in which the SOFC unit 100, which is a high-temperature fuel cell, and the absorption chiller 500 are combined like the fuel cell system S11, the fuel electrode exhaust gas and the air electrode exhaust air are burned by the burner in the combustion chamber 124. The hydrogen and methane remaining without reacting in the SOFC battery stack 110 are combusted to generate more water.

  The water generated in the combustion chamber 124 is contained in the combustion exhaust gas EG as steam because the combustion exhaust gas temperature is high. The combustion exhaust gas EG exchanges heat with water in the low-temperature water heat exchanger 61 as described above. Therefore, the temperature of the combustion exhaust gas EG on the outlet side of the low-temperature water heat exchanger 61 becomes 100 ° C. or less. Therefore, the steam contained in the combustion exhaust gas EG is condensed as drain water and stored at the bottom of the low-temperature water heat exchanger 61.

  The reformed gas introduced into the fuel cell stack has a sulfur content removed to prevent poisoning of the reforming catalyst and the battery cell catalyst by sulfur. Even in the fuel cell system S11, the sulfur content is removed before the fuel gas is introduced into the SOFC cell stack 110 by providing the desulfurizer 101. Therefore, sulfur is not contained in the produced water in which hydrogen and oxygen are reacted or in the combustion exhaust gas in which the reformed gas is combusted. For this reason, the drain water is close to pure water and can be recovered and used. Thus, in this embodiment, the drain water is extracted from the lower portion of the low-temperature water heat exchanger 61 through the generated water pipe 641 and is recovered in the generated water recovery tank 62. The water stored in the generated water recovery tank 62 is mixed with, for example, tap water by a pump and introduced into the low-temperature water heat exchanger 61 through the water circulation pipe 642 and used for hot water supply.

  As described above, the fuel cell system S11 including the exhaust heat / water recovery unit 600 uses the combustion exhaust gas EG that does not contain sulfur as a heating source of the regenerator 54. This system has greatly improved usability. That is, when city gas or petroleum-based fuel containing a odorant is used as a heating source for the regenerator 54, the temperature of the combustion exhaust gas cannot be reduced to 130 ° C. or less in view of the problem of corrosion of the flue pipe. The use of waste heat is naturally restricted. On the other hand, in this fuel cell system S11, since the sulfur content is not contained in the combustion exhaust gas EG, it becomes possible to use the combustion exhaust gas EG to a low temperature at which drain water is generated, and exhaust heat recovery. Efficiency is further improved.

  FIG. 4 is a block diagram showing a configuration of a fuel cell system S12 according to a modified embodiment of the embodiment shown in FIG. In this fuel cell system S12, fuel gas such as city gas is not desulfurized and reformed individually by each consumer and introduced into the fuel cell unit (SOFC unit 100), but is desulfurized and reformed in advance. This is different from the previous fuel cell system S11 in that (reformed gas RG) is supplied to the SOFC battery stack 110. Therefore, the fuel cell system S12 is not provided with the desulfurizer 101 and the reformer 120.

  That is, the fuel gas is supplied to the reformed gas RG in a state where it is supplied through the piping 104, and the reformed gas RG is opened through the main piping 102 by opening the valve 104 </ b> B so that the fuel electrode 121 of the SOFC battery stack 110. It is configured to be introduced. Note that the reformed gas RG can be introduced into the regenerator burner 50a through the bypass piping 103 by operating the valve 102B and the valve 103B.

  In the configuration such as the fuel cell system S12, fuel cell units that do not include a reformer are separately distributed to a plurality of consumers existing in a predetermined local area, and a centralized fuel gas common to these fuel cell units is provided. This can be achieved by installing a supply facility and supplying a desulfurized and reformed fuel gas (reformed gas RG) from the centralized fuel gas supply facility.

  This point will be briefly described with reference to FIGS. FIG. 5 is a block diagram showing a general fuel cell system. In this system, the fuel cell system unit 70 includes a fuel cell unit 71, a reformer 72, a control unit 73 that controls these operations, and hot water storage that generates hot water using the exhaust heat of the fuel cell unit 71. And a tank 74. The electricity generated by the fuel cell unit 71 is used by an electric device 75 in the consumer, and the hot water in the hot water storage tank 74 is used by a heat demanding device 76 such as a hot water supply facility. In such a system, raw fuel such as city gas is introduced into the reformer 72, and the reformed gas is purified by the reformer 72 and supplied to the fuel cell unit 71. In other words, the reformer 72 is provided in each of the fuel cell system units 70 individually provided for each consumer, and the reformed gas is purified for each consumer. The embodiment shown in FIG. 1 and FIG. 3 is such an individual reforming fuel cell system.

  However, when such an individual reforming type fuel cell system is introduced into a detached house or the like, it is difficult to follow the load fluctuation, and there is a disadvantage that the efficient operation of the fuel cell system cannot be performed. That is, in small-sized customers such as detached houses, generally large power load fluctuations are constantly occurring, but the load follow-up performance of a home fuel cell with a reformer is limited to about 10% / min. It cannot be operated following instantaneous load fluctuations. For this reason, household fuel cells are connected to the power system, and sudden load changes are supplied from the commercial power system, or backup power sources such as batteries are installed, It is necessary to adopt a configuration corresponding to the backup power source. In addition, the reformer has a long start-up time, and the fuel cell system cannot be started and stopped frequently in response to power and heat demand, and the fuel cell is efficient even when the power load and heat demand are low, such as at midnight. Therefore, there is a problem that the economy is deteriorated.

  Therefore, a concentrated reforming fuel cell system as shown in FIG. 6 is useful. This intensive reforming fuel cell system is a fuel cell for each of consumers A and B existing in a predetermined local area (for example, a single-family house group existing in an apartment house or a certain area). The units 700a and 700b are individually provided. For these fuel cell units 700a and 700b, for example, reformed gas or the like is unified from a common centralized fuel gas supply facility (centralized reformer 77). It is the structure supplied.

  That is, the fuel cell units 700a and 700b are composed of fuel cell units 701a and 701b, control units 703a and 703b, and hot water storage tanks 704a and 704b, and are not provided with individual reformers, and under the control of the control unit 77A. The reformed gas is purified from the raw fuel by the centralized reformer 77 and supplied to the consumers A and B. And the electric power and heat which generate | occur | produced in each fuel cell unit 700a, 700b are consumed by the electric equipment 711a, 711b and heat demand equipment 712a, 712b with which each consumer A, B is equipped. The fuel cell system S12 shown in FIG. 4 is a system that is suitably used as an equivalent to the fuel cell units 700a and 700b in such a concentrated reforming fuel cell system.

  For heat use by small consumers such as households, it is possible to eliminate the need for heat supply piping by installing fuel cell equipment in the consumer, which is the heat demand point, and extracting heat. It is the most economical from the viewpoint that heat loss can be suppressed. On the other hand, it is more practical to install a fuel gas supply apparatus having a large scale merit, high efficiency, and a centralized type that has the capacity for small fuel gas fluctuations. In view of such points, in the present invention, small fuel cell units 700a and 700b having no reformer are distributed and installed at each customer site, while the supply of reformed gas is a concentrated fuel gas supply. The system configuration is such that the equipment (central reforming device 77) is supplied in a lump and can be operated independently for each customer with respect to the power load (electric equipment 711a, 711b) and the heat load (heat demand equipment 712a, 712b). Is.

  According to such a configuration, even if each small fuel cell unit 700a, 700b is individually operated, the fuel gas supply amount as a whole of several, tens, hundreds of small fuel cell units is smoothed ( In other words, sudden load fluctuation does not occur as a whole), so that the aggregated fuel gas supply apparatus can be operated gently and can be economically operated. In the description of FIGS. 5 and 6, for convenience of explanation, a device equipped with a reformer as shown in FIG. 5 is called a “fuel cell system” and is reformed individually in a centralized reforming type as shown in FIG. A device that does not have a device is called a “fuel cell unit”, but in the other description of this specification, the term “fuel cell unit” includes a reformer or does not have a reformer. It includes both concepts of things.

  As described above, the central reforming fuel cell system has various advantages. However, since the small fuel cell units 700a and 700b are not provided with a reforming device, the fuel electrode exhaust gas and the air electrode discharged from the cell stack. Utilization of exhaust air becomes a problem. That is, in a general fuel cell unit having a reformer, the fuel electrode exhaust gas and air electrode exhaust air are burned by a reformer burner, or combustion exhaust gas burned in a combustion chamber is reformed by a reformer. It can be used as heat of reaction, but such a utilization cannot be performed in a central reforming fuel cell system. Thus, as in the fuel cell system S12 according to the present embodiment, the fuel electrode exhaust gas and the air electrode exhaust air are burned in the combustion chamber 124, and the combustion exhaust gas EG is used as a heating source of the regenerator 54 for effective use. Is possible. Therefore, the absorption refrigerating machine combined fuel cell system according to the present invention is particularly useful in a concentrated reforming fuel cell system as shown in FIG.

  In this fuel cell system S12, the high-temperature combustion exhaust gas EG discharged from the combustion chamber 124 is not used as a heat source for the reforming reaction, so the amount of heat discharged from the gas increases by about 20%. Accordingly, since the amount of exhaust heat is larger than that of the fuel cell systems S10 and S11 shown in FIG. 1 or FIG. 3, the absorption refrigerator capacity can be increased with respect to the fuel cell capacity.

(Second Embodiment)
FIG. 7 is a block diagram showing a configuration of a fuel cell system S20 according to the second embodiment of the present invention. The fuel cell system S20 has a system configuration in which a polymer electrolyte fuel cell (PEFC) unit 200 as a low-temperature fuel cell unit and an absorption refrigerator 500 are combined. The fuel cell system S20 uses the waste energy discharged from the PEFC battery stack 210 of the PEFC unit 200 as a heat source for externally heating the regenerator included in the absorption chiller 500. As a mechanism, a method is adopted in which fuel electrode exhaust gas and air electrode exhaust air discharged from the PEFC battery stack 210 are sent to a regenerator burner 50a for heating the regenerator of the absorption chiller 500 and burned. Hereinafter, the configuration of each part will be described in detail.

  The PEFC unit 200 includes a PEFC battery stack 210, an air supply device 250 including a blower, an exhaust heat recovery unit 300, an inverter (not shown), and the like. The PEFC battery stack 210 includes a fuel electrode 221, an air electrode 222, an electrolyte 223, and a cooling plate 224. Note that the reformed gas RG previously reformed is supplied to the PEFC battery stack 210 through the piping 104 and the main piping 102 in the same manner as in the embodiment shown in FIG. There are no separate reformers.

  In such a configuration, a hydrogen-rich reformed gas is introduced into the fuel electrode 221 from the centralized fuel gas supply device or the like via an accumulator or the like (and further via a humidifier if necessary). Is done. Thereafter, most of the hydrogen component in the introduced reformed gas is ionized at the fuel electrode 221, and the hydrogen ions are transferred to the air electrode 222 through the electrolyte 223. Air is introduced into the air electrode 222 from the air supply device 250 through the air piping 240, and oxygen in the air is taken in and ionized. The oxygen ions and hydrogen ions moved from the fuel electrode 221 chemically react to generate water and generate power. Since the electric power generated by such a chemical reaction is a direct current, it is converted into a direct current from a direct current by an inverter (not shown), and then supplied as a driving power source to various power devices existing in the consumer.

  In the PEFC battery stack 210, heat is generated because hydrogen and oxygen chemically react as described above. Therefore, although it is necessary to cool the PEFC battery stack 210 so as not to be overheated, the heat at the time of cooling is recovered by the exhaust heat recovery unit 300 to generate hot water or the like, thereby effectively utilizing the heat. In the example illustrated in FIG. 7, the exhaust heat recovery unit 300 is configured by a heat exchanger 30, a radiator 31, a pump 32, a circulation path 33, and a hot water tank 34.

  The PEFC battery stack 210 is provided with a cooling plate 224, and a cooling water circulation path 33 and a radiator 31 that pass through the cooling plate 224 are provided, and the cooling water is circulated in the circulation path 33 by the pump 32. Thus, the battery stack is kept at a constant temperature (cooled). On the other hand, the circulation path 33 is a piping path that also passes through the heat exchanger 30, and the heat exchanger 30 is disposed in the hot water storage tank 34. The heat exchanger 30 receives and transfers part of the heat absorbed by the cooling plate 224 (surplus heat) to the tap water introduced into the hot water tank 34 via the water pipe line 301. By such a heat exchange operation, hot water of about 60 ° C. is generated in the hot water tank 34. Such hot water is used for hot water storage tanks, kitchens, washrooms, and baths (heat demanding equipment) via the output piping 302.

  By the way, the hydrogen utilization rate in the fuel gas used in the fuel electrode 221 is about 80%, and the remaining 20% hydrogen gas and unreacted gas containing several percent of methane are used as fuel electrode exhaust gas together with carbon dioxide. The fuel electrode 221 is discharged. Moreover, the oxygen utilization rate in the air electrode 222 is about 50 to 60%, and nitrogen gas or the like that does not contribute to the reaction with the remaining oxygen is discharged from the air electrode 222 as air electrode exhaust air. In a general low-temperature fuel cell system, such fuel electrode exhaust gas and air electrode exhaust air are sent to a reformer burner and used as a heat source for reforming reaction. However, in the case of a centralized reforming fuel cell system in which reformed gas is supplied from a centralized fuel gas supply device or the like as in this embodiment, the reforming device becomes unnecessary in each fuel cell unit. It is necessary to effectively use the fuel electrode exhaust gas that can be used.

  Therefore, in this fuel cell system S20, the exhaust gas piping 241 connecting the outlet side of the fuel electrode 221 and the regenerator burner 50a, and the exhaust air piping 242 connecting the outlet side of the air electrode 222 and the regenerator burner 50a. The fuel electrode exhaust gas and the air electrode exhaust air can be introduced into the regenerator burner 50a. As a result, the fuel electrode exhaust gas discharged from the fuel electrode 221 and the air electrode exhaust air discharged from the air electrode 222 are combusted by the regenerator burner 50a of the absorption chiller 500 to heat the regenerator 54. As described with reference to FIG. 2, the water vapor content in the lithium bromide solution (absorbing liquid) stored in the regenerator 54 can be heated and expelled as vapor.

  Note that a bypass piping 103 that is directly connected to the main piping 102 is connected to the exhaust gas piping 241 without passing through the PEFC battery stack 210. Similarly, the exhaust air piping 242 is provided with a bypass piping 243 that is directly connected to the air piping 240 without passing through the PEFC battery stack 210. By providing such bypass piping paths 103 and 243, the absorption chiller 500 can be operated regardless of the operating state of the PEFC unit 200. That is, when the PEFC unit 200 is not in operation, the absorption chiller 500 is operated by opening the valve 103B and the valve 243B and supplying fuel gas and air to the regenerator burner 50a. It is configured to be able to.

  Combustion exhaust gas EG generated by burning the fuel electrode exhaust gas and the air electrode exhaust air with the regenerator burner 50a is guided to the low-temperature water heat exchanger 61 as described in the first embodiment, and the water circulation pipe 642 The water is exchanged with tap water. Low-temperature water LW is generated by such heat exchange and used for hot water supply. Furthermore, since this combustion exhaust gas EG does not contain a sulfur content, the moisture contained as water vapor in the combustion exhaust gas EG is recovered as drain water.

  According to the fuel cell system S20 as described above, a general PEFC unit (low temperature type fuel cell unit) can generate only low temperature water of about 60 ° C. using exhaust heat, and in such a low temperature type fuel cell unit, Although the cooling demand could not be met, the absorption refrigerator 500 can be used by combusting the fuel electrode exhaust gas and the air electrode exhaust air discharged from the battery stack with the regenerator burner 50a. It becomes possible to cope with. Therefore, the fuel cell system S20 can be used efficiently throughout the year, and the facility utilization rate can be improved.

  FIG. 8 is a block diagram showing a configuration of a fuel cell system S21 according to a modified embodiment of the second embodiment. This fuel cell system S21 is a useful system when it is assumed that the frequency of using the absorption chiller 500 is low. That is, this fuel cell system S21 is different from the fuel cell system S20 shown in FIG. 7 in that a hot water storage temperature increasing burner 26 is provided to increase the temperature of hot water (water) stored in the hot water storage tank 34. To do.

  The fuel electrode exhaust gas and the air electrode exhaust air discharged from the PEFC battery stack 210 are used as the fuel for the hot water storage temperature increasing burner 26. Therefore, the branch exhaust gas pipe line 251 and the branch exhaust air pipe line 252 are branched from the exhaust gas pipe line 241 and the exhaust air pipe line 242 that lead the fuel electrode exhaust gas and the air electrode exhaust air to the regenerator burner 50a, respectively. It is connected to a hot water storage temperature raising burner 26. The exhaust gas piping 241 and the exhaust air piping 242 are provided with valves 241B and 242B, respectively, and the branch exhaust gas piping 251 and the branch exhaust air piping 252 are also provided with valves 251B and 252B, respectively. .

  When the absorption refrigerator 500 is not used, the valves 241B and 242B are closed, while the valves 251B and 252B are opened, and the fuel electrode exhaust gas and the air electrode exhaust air are combusted by the hot water storage temperature increasing burner 26. Let The hot water storage temperature increasing burner 26 is provided with a circulation pipe line 27 for pumping hot water (water) from the hot water storage tank 34 and returning it to the hot water storage tank 34 so that heat can be transferred. The hot water in the hot water storage tank 34 is heated from about 60 ° C. to about 90 ° C. by the combustion of 26. Therefore, even when the absorption chiller 500 is used less frequently, the exhaust energy discharged from the PEFC battery stack 210 can be used effectively.

(Third embodiment: Embodiment as a central reforming fuel cell system)
In the application of the present invention, as described above with reference to FIG. 6, the concentration common to each consumer with respect to the fuel cell power generation units dispersedly arranged in the (local) consumers existing in a predetermined local area. It is desirable to provide a type fuel gas supply facility (centralized reformer) and to supply, for example, reformed gas from the centralized fuel gas supply facility in an integrated manner. Hereinafter, such a concentrated reforming fuel cell system will be described.

  Before describing such an embodiment, a general power and gas supply system will be outlined. FIG. 9 is a block diagram showing a form of supplying power and gas to a typical detached house or apartment house. The consumers A, B, E, and G have a polymer electrolyte fuel cell (PEFC) system 200a, the consumers C and F have a solid oxide fuel cell (SOFC) system 100a, and the consumers D and H have General gas appliances 400 (the fuel cell power generation system is not yet introduced) are arranged. For each consumer A to H, gas is individually supplied from a commercial gas supply source 770G via a commercial gas supply system (city gas pipe) 770, and power is supplied from a commercial power supply source 780G to a commercial power supply system. It is supplied individually via 780. That is, each of the consumers A to H individually contracts with a commercial gas supply company or a commercial power supply company even if the fuel cell systems 100a and 200a are introduced, and the commercial gas supply system 770 Gas and power are supplied through the power system 780.

  On the other hand, FIG. 10 is a block diagram showing a basic configuration of the intensive reforming fuel cell system S30. Here, the consumers A to H are a plurality of small consumers existing in a predetermined local area, for example, each household of an apartment house, a single-family house in a predetermined area, or a small business consumer. While the customers A, B, E, and G have the polymer electrolyte fuel cell (PEFC) units 200 and the customers C and F, the solid oxide fuel cell (SOFC) units 100 are distributed. The general gas appliance 400 (the fuel cell power generation unit has not been introduced) is disposed at the consumers D and H. In addition, general gas appliances are also installed in consumers where the fuel cell units 100 and 200 are introduced.

  Each of the fuel cell units 100 and 200 is combined with an absorption refrigerator 500. That is, the fuel cell system S12 as shown in FIG. 4 is installed for the consumers A, B, E, and G, and the fuel as shown in FIG. 7 or FIG. Battery systems S20 and S21 are installed. And about electric power, it is the form supplied separately to each consumer AH through the commercial power supply system 780 from the commercial power supply source 780G similarly to the normal supply form shown in FIG. Is configured to be individually supplied to each of the consumers A to H via the centralized fuel gas supply device 77 and the accumulator 720.

  That is, a source gas such as city gas is supplied from the commercial gas supply source 770G through the commercial gas supply system (city gas pipe) 770 to the centralized fuel gas supply device 77, and the centralized fuel gas supply device 77 modifies the source gas. The quality gas is purified, and this reformed gas is supplied to each consumer A to H via the accumulator 720. As the fuel used in the centralized fuel gas supply device 77, petroleum-based liquid fuels such as kerosene, light oil, naphtha, and biogas may be used in addition to city gas. Furthermore, hydrogen gas produced by water electrolysis using sunlight and midnight power can be mixed and supplied together with these reformed gases.

  The accumulator 720 is installed to store a certain amount of the reformed gas and maintain the reformed gas pressure at a constant level even when a sudden demand change of the reformed gas occurs. The reformed gas may be a local pipe line 721 (an existing city gas pipe line or the like connected to the accumulator 720. Note that the pipe line 104 shown in FIGS. And the SOFC unit 100, the PEFC unit 200, and the general gas appliance 400 provided in each of the consumers A to H. In addition, although the electric power used by each consumer AH is covered by the electric power generation by a fuel cell system, it is set as the structure purchased for every consumer from the commercial system 110 about the shortage.

  FIG. 11 is a block diagram showing an example of the internal configuration of the centralized fuel gas supply device 77. This centralized fuel gas supply device 77 includes a centralized fuel gas reformer 771 that generates reformed gas, and a centralized carbon monoxide selective oxidation as a carbon monoxide remover that lowers the carbon monoxide concentration of the reformed gas. And a container 16. The centralized fuel gas reformer 771 includes a desulfurizer 791 having a sulfur removal function, a steam supplier 792 that generates steam and adds steam to the raw fuel, and a reformer that performs a reforming reaction. (Reformer) 793, a carbon monoxide converter 794 for performing a shift reaction for generating hydrogen and carbon dioxide, and a reformer burner 795 for heating the reformer 793 are provided.

The operation of such a concentrated fuel gas supply device 77 will be described. A raw fuel such as city gas supplied from the commercial gas supply source 770G (CH ₄ is used in the present embodiment) is first introduced into the desulfurizer 791, and the sulfur component of the odorous material contained in the raw fuel. Is removed. Steam is added from the steam supply unit 792 to the desulfurized gas and introduced into the reformer 793. The reformer 793 is heated to an operating temperature of about 750 to 800 ° C. by the reformer burner 795, and the introduced CH ₄ and water are reformed in the reformer 793 using a Ni-based catalyst. , Separated into hydrogen and carbon monoxide. Thereafter, the separation gas is introduced into a carbon monoxide converter 794 maintained at a temperature of 350 to 200 ° C., and the carbon monoxide is converted into hydrogen and carbon dioxide using an Fe-based catalyst or a Cu-based catalyst. . Thereby, the carbon monoxide concentration in the fuel gas (reformed gas) is reduced to about several percent.

  By the way, in the PEFC type fuel cell, it is necessary to supply the reformed gas after the carbon monoxide concentration in the gas is lowered (about 10 to 100 ppm or less). Therefore, in the case where the PEFC units 200 are mixed as in the embodiment shown in FIG. 10, if the reformed gas purified by the centralized fuel gas reformer 771 is supplied as it is, the PEFC unit 200 is installed. In some customers A, B, E, and G, it is necessary to individually install a carbon monoxide concentration reducing device. Therefore, in this embodiment, a centralized carbon monoxide selective oxidizer 772 for reducing the carbon monoxide concentration of the reformed gas is provided on the outlet side of the centralized fuel gas reformer 771. Note that a centralized carbon monoxide adsorber or the like can be used instead of the centralized carbon monoxide selective oxidizer 772, and any device having a function of reducing the carbon monoxide concentration may be used.

  With this configuration, the reformed gas is supplied to the accumulator 720 after the concentration of carbon monoxide contained in the reformed gas purified by the centralized fuel gas reformer 771 is reduced. . That is, the reformed gas purified in the centralized fuel gas reformer 771 contains carbon monoxide at a level of several percent. Such reformed gas is introduced into a centralized carbon monoxide selective oxidizer 772 heated to about 100 ° C., and the carbon monoxide component is converted into carbon dioxide using a Pt-based catalyst. By such a conversion operation, the carbon monoxide concentration of the reformed gas output from the centralized carbon monoxide selective oxidizer 772 is reduced to about 10 to 100 ppm or less.

  In this way, the reformed gas obtained by refining the city gas in the centralized fuel gas supply device 77 is appropriately sent to each consumer A to H via the accumulator 720. In this embodiment, a shunt 7941 is provided in the outlet side piping line of the carbon monoxide transformer 794, and a part of the reformed gas purified in the centralized fuel gas reformer 771 is supplied to the reformer burner. 795. This makes it possible to reduce the amount of NOX generated by the combustion of the reformer burner 795 to a lower concentration (about 10 ppm) than when using raw fuel such as city gas, LPG, or kerosene. There are advantages that the improvement of the above can be achieved and that the residual gas can be effectively used.

  Furthermore, the PEFC unit 200 is installed by using the centralized carbon monoxide selective oxidizer 772 to reduce the reformed gas to a low carbon monoxide concentration and supplying the reformed gas to each consumer A to H from the centralized fuel gas supply device 77. Also in the consumers A, B, E, and G who are doing, it becomes possible to introduce the said reformed gas into the PEFC unit 200 as it is, and to achieve simplification and size reduction of the PEFC unit 200. In addition, a phosphoric acid fuel cell (PAFC), a molten carbonate fuel cell (MCFC), and the like that require supply of a reformed gas having a low carbon monoxide concentration can also be applied to the fuel cell system. Note that the general gas appliance 400 is used by modifying the burner structure to be suitable for the reformed gas combustion. Furthermore, if the carbon monoxide concentration is 10 ppm or less, it can be used in conformity with the current Industrial Safety and Health Law, Building Standard Law, Building Management Law, and School Sanitation Law. If a gas leak occurs, there is no possibility of carbon monoxide poisoning, and a gas supply system that is preferable in terms of safety can be obtained.

  Returning to FIG. 10, the operation of the concentrated reforming fuel cell system S30 according to the present embodiment described above will be described. In this system, fuel gas (reformed gas) is refined from raw fuel (city gas) in a batch by a centralized fuel gas supply device 77 for small consumers A to H existing in a predetermined local area. And distributed to each consumer A to H via the accumulator 720. And in each consumer AH, the supply of the said reformed gas is received by opening and closing a supply valve (valve 104B shown in FIG.4, FIG.7, FIG.8) suitably, and the fuel with which each consumer AH is equipped. A battery unit or the like is operated.

  That is, in the consumers A, B, E, and G, when the PEFC unit 200 is operated, the valve 104B is opened, the reformed gas is introduced into the fuel electrode 221 and the operation is executed. In addition, in the customers C and F, when the SOFC unit 100 is operated, the valve 104B is opened, and the reformed gas is introduced into the fuel electrode 121, and the operation is executed. On the other hand, in the consumers D and H into which the fuel cell unit is not introduced, the reformed gas can be supplied to the general gas appliance 400, and the reformed gas is used when the general gas appliance 400 is used. It will be.

In the consumer where the SOFC unit 100 or the PEFC unit 200 is arranged, the electric power generated by the operation of each SOFC unit 100 or the PEFC unit 200 is individually utilized as an operation power source of the electric equipment in each consumer. The The insufficient power is purchased individually from the commercial power supply source 780G. Further, the exhaust heat generated by the operation of the SOFC unit 100 or the PEFC unit 200 is as shown in FIGS. 4, 7, and 8.
The regenerator 54 of the absorption chiller 500 combined with each SOFC unit 100 and PEFC unit 200 is used as a heating source for externally heating. Alternatively, the exhaust heat and tap water are heat-exchanged, and are used individually as hot water in each consumer.

  According to the centralized reforming fuel cell system S30 according to the present embodiment described above, (small) fuel cell units (SOFC unit 100 or PEFC unit 200) or general gas appliances 400 distributed and installed in a plurality of small consumers. Is supplied by a centralized fuel gas supply device 77 common to each consumer, while the SOFC unit 100 or PEFC installed in each consumer is used for the electric load and heat load of each consumer. This is a configuration corresponding to each unit 200 individually. Therefore, each fuel cell unit does not require a reformer unit, and the device configuration can be simplified and downsized. In addition, since the reformed gas can be constantly supplied, the start-up time is shortened and the fuel cell unit can be operated efficiently. Furthermore, since it respond | corresponds individually using the waste heat of the SOFC unit 100 or PEFC unit 200 with which each consumer is provided with respect to a heat load, the heat loss by heat transport can be suppressed to the minimum.

  Furthermore, since each fuel cell unit does not require a reformer unit, waste energy (exhaust heat) discharged from the SOFC battery stack 110 or the PEFC battery stack 210 cannot be utilized in the reformer system. According to the embodiment, the absorption chiller 500 is combined with each SOFC unit 100 or PEFC unit 200, and the exhaust energy is used as a heating source for heating the regenerator 54 externally. In addition, exhaust energy (exhaust heat) is also effectively utilized, and a highly economical system can be obtained.

  The central reforming fuel cell system S30 may be provided with a shared power system that interconnects power supply systems to consumers. In this case, all the power generated by each fuel cell unit is once sent to the shared power system, and each customer purchases the amount of power to be used individually from the shared power system, from the power generated by each fuel cell unit, Surplus power excluding power consumption at each consumer is sent to the shared power grid, and each customer purchases the amount of power used from the shared power grid, or the heat generated from the fuel cell unit of each consumer While the individual power is used by the consumer, the total surplus of the power generated by the fuel cell unit is sold through the shared power system, and the insufficient power is purchased in bulk by the consumer in the local area Etc. can be executed.

  Further, a plurality of the above-described concentrated reforming fuel cell systems S30 may be provided, and the fuel gas may be coordinated between these systems. That is, in the first fuel cell system in which a centralized fuel gas supply device having a fuel gas supply system is installed for each consumer in the first local area, and in the second local area adjacent thereto, And a second fuel cell system in which a centralized fuel gas supply device having a fuel gas supply system is installed for each consumer, the refinement is performed by the centralized fuel gas supply device of each fuel cell system. It is also possible to provide a connecting pipe line or the like for enabling the fuel gas to be supplied to other fuel gas supply systems so that the fuel gas can be interchanged.

It is a block diagram which shows the structure of fuel cell system S10 concerning 1st Embodiment of this invention. It is a block diagram which shows an example of an internal structure of an absorption refrigerator. It is a block diagram which shows the structure of fuel cell system S11 concerning the modified embodiment of the said 1st Embodiment. It is a block diagram which shows the structure of fuel cell system S12 concerning the modified embodiment of the said 1st Embodiment. 1 is a block diagram schematically showing a configuration of a general fuel cell system. 1 is a block diagram schematically showing the configuration of a intensive reforming fuel cell system according to the present invention. FIG. It is a block diagram which shows the structure of fuel cell system S20 concerning 2nd Embodiment of this invention. It is a block diagram which shows the structure of fuel cell system S21 concerning the deformation | transformation embodiment of the said 2nd Embodiment. It is a block diagram which shows the supply form of the electric power and gas with respect to a normal detached house and an apartment house. It is a block diagram which shows the structure of intensive reforming type fuel cell system S30 concerning 3rd Embodiment of this invention. It is a block diagram which shows an example of an internal structure of a concentrated fuel gas supply apparatus. It is a block diagram which shows the structure of the conventional PEFC system. It is a block diagram which shows the structure of the conventional SOFC system.

Explanation of symbols

100 SOFC unit (fuel cell unit)
102 Main piping (fuel gas piping system)
103 Bypass piping (bypass piping system)
104 Pipe line (local pipe line)
110 SOFC battery stack 200 PEFC unit (fuel cell unit)
210 PEFC battery stack 500 Absorption refrigerator 50a Regenerator burner 51 Condenser 52 Evaporator 53 Absorber 54 Regenerator 61 Low temperature water heat exchanger (heat exchanger for recovering low temperature water exhaust heat)
62 Generated water recovery tank (water recovery device)
77 Centralized fuel gas supply system (centralized fuel gas supply equipment)
720 Accumulator 770 Commercial gas supply system A to H Customer EG Combustion exhaust gas

Claims (8)

A fuel cell system in which a fuel cell unit that introduces fuel gas into a battery stack to generate electricity and an absorption chiller including a regenerator are combined,
An absorption chiller having a waste energy utilization mechanism for using the waste energy discharged from the battery stack of the fuel cell unit as a heating source for externally heating the regenerator of the absorption chiller. Combined fuel cell system. The fuel cell unit comprises a high-temperature fuel cell unit;
The absorption according to claim 1, wherein the exhaust energy utilization mechanism directly heats the regenerator of the absorption refrigeration machine with the high-temperature combustion exhaust gas discharged from the battery stack of the high-temperature fuel cell unit. -Type refrigerator combined fuel cell system. The fuel cell unit comprises a low-temperature fuel cell unit;
The exhaust energy utilization mechanism sends the fuel electrode exhaust gas and the air electrode exhaust air discharged from the battery stack of the low temperature type fuel cell unit to the regenerator burner for heating the regenerator of the absorption refrigeration machine and combusts it. The absorption refrigerating machine combined fuel cell system according to claim 1, wherein: The fuel cell unit is distributed to a plurality of customers existing in a predetermined local area,
The fuel cell unit disposed at each consumer has a configuration in which fuel gas is supplied from a centralized fuel gas supply facility that is connected to a commercial gas supply system and purifies the fuel gas that is the driving source of the fuel cell in a batch. The absorption refrigerating machine combined fuel cell system according to any one of claims 1 to 3, further comprising: A bypass piping system is provided in the fuel gas piping system introduced into the battery stack,
The absorption refrigerating machine combined fuel cell system according to any one of claims 1 to 4, wherein the bypass piping system is connected to a regenerator burner for heating the regenerator of the absorption refrigerating machine. .   Heat for recovering low-temperature water exhaust heat from the combustion exhaust gas after the combustion exhaust gas directly heated by the refrigerating machine of the absorption chiller or the exhaust gas from the regenerator burner provided in the absorption chiller 6. The absorption refrigerating machine combined fuel cell system according to claim 1, wherein the fuel cell system is passed through an exchanger.   The absorption type according to claim 6, further comprising a water recovery device that recovers water contained in the combustion exhaust gas as drain water when recovering the low-temperature water exhaust heat from the combustion exhaust gas by the heat exchanger. Refrigerator combined fuel cell system. A fuel gas supply facility that is connected to a commercial gas supply system and purifies a fuel gas serving as a drive source for the fuel cell, a fuel cell unit that is distributed in a plurality of consumers in a predetermined local area, and a regenerator A fuel cell system comprising an absorption refrigeration unit comprising:
The fuel gas supply facility is a centralized fuel gas supply facility common to each fuel cell unit capable of supplying fuel gas to each consumer,
The fuel cell unit is an individual fuel cell unit that generates electric power to be supplied to at least an electric power load in each consumer,
The absorption refrigeration unit has a waste energy utilization mechanism for using waste energy discharged from a battery included in the fuel cell system as a heating source for heating the regenerator of the absorption chiller. Absorption type refrigerator combined fuel cell system.

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