JPH07226223A - Fuel cell - Google Patents

Abstract

PURPOSE:To enhance heat recovery efficiency by once returning high temperature cooling water circulated from a steam separator to a fuel cell to the steam separator without sending to a load, sending high temperature steam having a specified temperature from the steam separator to a high temperature heat load, and arranging an ejector of a heat pump in high temperature steam piping. CONSTITUTION:High temperature warm water sent from a steam separator 6 is passed into cooling fine holes in a separator placed between cells of a fuel cell main body 3, high temperature steam coming out from the fine holes is heat-exchanged by a high temperature heat load 10 and condensed, then returned to the steam separator 6. Low temperature warm water for cooling water is circulated to an exhaust gas condenser 2 for recovering water from exhaust gas of a fuel reformer 1 which supplies hydrogen to the fuel cell main body 3, and the low temperature warm water is supplied to a low temperature heat load 11. Part of calorie supplied to the low temperature heat load 11 is sent to the high temperature heat load 10, and by an ejector 12 and an evaporator 13 arranged between the steam separator 6 and the high temperature heat load 10, a heat pump A which draws heat from the low temperature side to the high temperature side is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a demand location type fuel cell for supplying electric power and heat to facilities such as factories, hotels and hospitals.

[0002]

2. Description of the Related Art FIG. 1 is a schematic system diagram of a fuel cell of this type, in which natural gas and water vapor taken in by an ejector 7 are supplied to a fuel reformer 1 and these are provided in a catalyst. The hydrogen obtained by the reaction is the fuel cell body 3
The heat of the exhaust gas supplied to the exhaust gas condenser 2
Will be collected at. In the fuel cell body 3, hydrogen reacts with oxygen in the air to generate electricity and heat. Since this electricity is DC, it is converted to AC for general use by the inverter 4,
The heat generated in the fuel cell body 3 is recovered by the exhaust heat recovery device 5. Further, the water recovered by the exhaust gas condenser 2 is converted into steam by the exhaust heat from the fuel cell main body 3 by the steam generator 6 and sent to the ejector 7. In this way, the energy utilization efficiency of the entire fuel cell is extremely high, and the power generation efficiency is about 4
0%, exhaust heat recovery efficiency is about 40%, and heat wasted by exhaust gas is about 20%.

FIG. 2 specifically shows the configuration of FIG. 1. The exhaust heat recovery device 5 in FIG. 1 includes a steam separator 6 as a steam generator, a separator of the fuel cell body 3, and a high temperature heat load. It is composed of a heat exchanger and the like interposed in the route to 7. The pressure in the steam separator 6 is maintained at 6 to 7 atm, from which the fuel cell body 3 is cooled to about 160 ° C. as cooling water.
Hot water is sent out, and the exhaust heat is recovered as high temperature steam of about 170 ° C. The fuel cell main body 3 is formed by stacking a large number of single cells (cells) in which an electrolyte matrix is sandwiched between a fuel electrode and an air electrode using a platinum catalyst with a separator interposed therebetween, and the fuel cell main body 3 is provided in this separator. Cooling water is passed through a large number of pores to maintain the cell at a temperature of about 175 to 190 ° C. suitable for the reaction, and the high temperature steam coming out of the fuel cell main body 3 is heat-exchanged by the high temperature heat load 10 to be steamed. Return to separator 6.

The water vapor evaporated in the steam separator 6 becomes a raw material for generating hydrogen by being mixed with natural gas (main component: CH4) by the ejector 7 provided at the natural gas supply port of the fuel reformer 1. In the steady state, the heat required for the reaction in the fuel reformer 1 is supplied by the combustion of the surplus hydrogen returning from the fuel electrode of the fuel cell body 3. Therefore, the exhaust gas from the fuel reforming apparatus 1 contains a large amount of water vapor, and this water vapor is condensed in the exhaust gas condenser 2, purified by the pure water device 8, and then returned to the steam separator 6. . The heat of condensation at this time is taken out from the exhaust gas condenser 2 as hot water of about 55 ° C., and is circulated and supplied to the low temperature heat load 11 by the pump 9.

[0005]

In the conventional fuel cell, the heat recovery efficiency is about 40% as described above, and about half of the heat recovered is high in the form of high temperature steam at 160 ° C to 170 ° C. The utility value is high because it is supplied to the thermal load 10, but the other half is low in utility value because it is supplied to the low-temperature heat load 11 as hot water having a relatively low temperature of about 55 ° C. Sometimes you can't find
There was a problem that the substantial heat recovery efficiency was not so high. Therefore, an object of the present invention is to improve the exhaust heat recovery device of a fuel cell to increase the ratio of good quality heat quantity that can be used in high temperature heat utilization equipment.

[0006]

The fuel cell according to the present invention, as shown in FIGS. 3 to 4, is a fuel cell in which the amount of heat generated by power generation is taken out as high temperature saturated steam and low temperature hot water. Lead to the evaporator, suck the vapor in the evaporator by the ejector interposed in the path of the high temperature saturated vapor, supply the output vapor of the ejector to the high temperature heat load, and the low temperature hot water remaining in the evaporator. Is supplied to the low temperature heat load.

[0007]

In the evaporator 13, hot water of about 55 ° C. is steamed by the sprayer 14, and the vapor is sucked by the ejector 12. Therefore, the vaporized gas 3 is depressurized to about 0.1 atm, and the sucked vapor. The heat of vaporization is deprived of by and the temperature drops to about 45 ° C. On the high temperature side, a large amount of saturated steam of 45 ° C. is sucked into the steam of about 170 ° C. and 6 to 7 atm from the low temperature side together with the latent heat. Although the flow rate decreases, the flow rate increases significantly, and as a result, about 1.5 times as much heat as the conventional amount is supplied to the high temperature heat load 10 having a high energy effective utilization rate.

[0008]

EXAMPLE FIG. 3 shows an example of the present invention, in which high temperature hot water sent from the steam separator 6 is supplied to the cooling pores provided in the separator between the cells of the fuel cell body 3. The high-temperature steam that has been passed through and is heat-exchanged by the high-temperature heat load 7 is condensed and returns to the steam separator 6. On the other hand, low temperature hot water for cooling is circulated in the exhaust gas condenser 2 for recovering water from the exhaust gas of the fuel reforming apparatus 1 which supplies hydrogen to the fuel cell body 3, and the low temperature hot water is applied to the low temperature heat load 11. It is being supplied. In the present invention, a part of the heat quantity supplied to the low-temperature heat load 11 is directed to the high-temperature heat load 10, and is inserted in the path from the steam separator 6 to the high-temperature heat load 10. The ejector 12 sucks saturated vapor from the evaporator 12 provided in the path of the low temperature hot water,
The output steam of the ejector 12 is supplied to the high temperature heat load 7, and the low temperature hot water remaining in the evaporator 13 is supplied to the low temperature heat load 11. The ejector 12 and the evaporator 13 allow the low temperature side water to flow from the low temperature side. The heat pump A for pumping heat to the high temperature side is formed.

In FIG. 3, the fuel cell main body 3 is cooled by the high temperature hot water sent from the steam separator 6 at 6 to 7 atmospheres 160 ° C., and the high temperature steam discharged from the fuel cell main body 3 is applied to the high temperature heat load 7. An ejector 12 is provided in the sending pipe, and an evaporator 13 provided with a sprayer 14 is provided in the pipe in which low temperature hot water of about 55 ° C. is circulated and supplied from the exhaust gas condenser 2 to the low temperature heat load 11 by the pump 9. The ejector 12 sucks saturated vapor at a temperature of about 45 ° C. evaporated from the ejector 12.
The output steam of the above is supplied to the high temperature heat load 7, and the evaporator 1
The low temperature hot water of about 45 ° C. remaining in 3 is supplied to the low temperature heat load 11, and the heat pump A formed by the ejector 12 and the evaporator 13 reduces the amount of heat supplied to the low temperature heat load 11. It is possible to pump half up to the hot side. In the figure, 15 is a steam trap that cuts off steam and allows only condensed water to pass through, and 16 is an electromagnetic valve controlled by a liquid level switch 17, and the condensed water corresponding to the amount of steam sucked by the ejector 12 is evaporated 13 It is for returning to the inside. With this configuration, the high temperature heat load 10 with a high effective utilization rate of heat quantity is about 30 times as much as 1.5 times the conventional input of natural gas.
%, 10% of the heat amount, which is half that in the conventional case, is supplied to the low-temperature heat load 11 having a low effective utilization rate, and the quality of recovered heat could be improved.

FIG. 4 shows another embodiment of the present invention, in which the hot-water cooling water circulated from the steam-water separator 6 to the fuel cell main body 3 is not sent to the load 10 and is once steam-water separator 6. The high temperature steam of about 160 ° C. is sent from the steam separator 6 to the high temperature heat load 10, and the high temperature steam pipe is provided with the ejector 12 of the heat pump A. Other configurations are shown in FIG. Is the same.

[0011]

As described above, according to the present invention, of the exhaust heat recovered from the conventional fuel cell, the ratio of the amount of heat at high temperature that can be effectively used can be increased from 50% to 75%.
This has the advantage that the substantial heat recovery efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a schematic system diagram of a conventional fuel cell.

FIG. 2 is a specific system diagram of the above.

FIG. 3 is a system diagram of an embodiment of the present invention.

FIG. 4 is a system diagram of another embodiment of the present invention.

[Explanation of symbols]

 1 Fuel Reforming Device 2 Exhaust Gas Condenser 3 Fuel Cell Body 4 Inverter 5 Exhaust Heat Recovery Device 6 Steam-Water Separator 7 Ejector 8 Pure Water Device 9 Pump 10 High Temperature Heat Load 11 Low Temperature Heat Load 12 Ejector 13 Evaporator A Heat Pump

Claims (3)

[Claims] 1. A fuel cell in which the amount of heat generated by power generation is taken out as high temperature saturated steam and low temperature hot water,
The low-temperature hot water is guided to an evaporator, and the vapor in the evaporator is sucked by an ejector interposed in the path of the high-temperature saturated vapor, and the output steam of the ejector is supplied to a high-temperature heat load, and the evaporator is also provided. A fuel cell configured to supply low temperature hot water remaining in the fuel cell to a low temperature heat load. 2. High-temperature hot water sent from a steam separator is passed through cooling pores provided in a separator between cells in a fuel cell body, and the high-temperature steam that comes out is heat-exchanged by a high-temperature heat load. After being condensed, it is returned to the steam separator, and low-temperature hot water for cooling is circulated in the exhaust gas condenser that collects water from the exhaust gas of the fuel reformer that supplies hydrogen to the fuel cell body, and the low-temperature hot water is cooled to a low temperature. A fuel cell configured to supply heat load, in which vapor is sucked from an evaporator provided in the path of the low-temperature hot water by an ejector interposed in the path of the high-temperature steam. 3. The high-temperature steam for cooling is circulated from the steam-water separator to the fuel cell main body, and the high-temperature steam sent from the steam-water separator to the high-temperature heat load is condensed by the load and returned to the steam-water separator. A low temperature hot water for cooling is circulated in an exhaust gas condenser for recovering water from an exhaust gas of a fuel reforming device for supplying hydrogen to a fuel cell body, and the low temperature hot water is supplied to a low temperature heat load. In the fuel cell, in which the evaporation is sucked from the evaporator provided in the path of the low temperature hot water by the ejector interposed in the path from the steam separator to the high temperature heat load.