JP2619947B2 - Fuel cell generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a structure of a reformed steam generation system and a fuel cell cooling system of a water-cooled fuel cell power generator, and more particularly to an improvement in temperature control characteristics at start and stop thereof. About.

[Conventional technology]

A fuel cell power generator is a reformer that generates hydrogen-rich gas by steam reforming using natural gas, methanol, etc. as raw materials, and a fuel cell that uses hydrogen generated by this reformer as fuel and generates power as an oxidizing agent for air. , And a quadrature converter for converting a DC output of the fuel cell into an AC. When power generation is started in this fuel cell power generator, first, a mixed gas of a raw material gas and steam is introduced into a reformer to perform a reforming reaction, and equipment for generating steam (saturated steam at about 160 ° C.) for this purpose is provided. Must be possessed as equipment. Further, in order to generate power, the temperature of the battery main body must be raised to about 130 ° C. Therefore, it is necessary to put an electric heater or the like in the battery cooling water system to raise the temperature. Therefore, it is known that two devices such as a steam generating boiler and a battery heating heater are provided for startup.

Further, when the operation of the fuel cell is stopped, cooling water having a high temperature of, for example, 160 ° C. or more is cooled by heat generated by power generation of the fuel cell to cool the fuel cell temperature to a temperature suitable for storage of, for example, 80 ° C. or less. However, in many cases, natural cooling is often required.

[Problems to be solved by the invention]

In order to avoid complication of the configuration in the conventional apparatus having a heat source for generating steam and a heat source for preheating the battery, an electric heater is provided in the battery cooling water system by using both heat sources, and the cooling water is cooled to 130 ° C at the start of power generation. By preheating the fuel cell by heating it to an appropriate level, and using the heated cooling water as a steam generation source, during power generation operation, control the on / off control by narrowing the cooling water passing through the fuel cell to a very small flow rate. Attempts have been made to maintain the fuel cell at its operating temperature.However, although the electron temperature can be maintained at a certain operating temperature, a considerable temperature difference occurs in the vertical direction of the stacked fuel cell, resulting in a difference in output characteristics between the individual cells. There is a problem that the deterioration of the output characteristics and the deterioration of the electrode catalyst phase are promoted due to this, and improvement thereof is required.

On the other hand, when the fuel cell is at a high operating temperature when the power generation operation is stopped and the inert gas is purged to stop the power generation operation, a delay in the reaction gas purge causes some of the single cells to perform a sintering phenomenon. There is a problem that a reduction in the effective reaction area of the electrode catalyst occurs, which leads to a reduction in output characteristics.

SUMMARY OF THE INVENTION It is an object of the present invention to share a heat source for a steam generation system and for preheating a fuel cell without adversely affecting the output characteristics of the fuel cell, and to reduce the temperature during operation shutdown in a shorter time and more efficiently than a conventional device. It is another object of the present invention to obtain a steam generation system and a cooling system of the obtained water-cooled fuel cell.

[Means for solving the problem]

According to the present invention, there is provided a fuel cell comprising a fuel cell, a steam separator for supplying steam to a raw fuel steam reformer system, and a cooling water circulation system for circulating cooling water therethrough. In the battery power generator, the steam separator is a heating circulating system that raises the temperature of the stored water to a temperature suitable for starting the fuel cell by an electric heater when the fuel cell is started, and a temperature controller that adjusts the temperature of the stored water. The cooling water circulation system is configured to sequentially connect a cooling water outlet of the fuel cell, a three-way valve, a steam separator, a pump for cooling water circulation, and a cooling water inlet of the fuel cell. A branch circulation system for separating, the branch circulation system includes the three-way valve, a cooler that cools the cooling water when the fuel cell is stopped, and a three-way valve that is provided for adjusting a fuel cell inlet cooling water temperature. Type temperature control valve The cooling water outlet of one of the three-way valve type temperature control valve is further connected to the three-way valve of the cooling water circulation system and the steam separator, and the other cooling water outlet is connected to the cooling water outlet. A pipe is connected between the steam separator of the cooling water system and the pump.

[Action]

In the above means, at the time of starting the fuel cell, the stored water in the steam separator is heated to a predetermined temperature by a heating circulation system having an electric heater to generate steam, and the heated steam is supplied to the steam reformer system to supply raw steam to the steam reformer system. In addition to starting steam reforming and the like, the stored water is circulated to the fuel cell through a separation circulation system having a temperature control valve as a heating medium to heat the fuel cell to its starting temperature. The cooling water heated by heat is circulated through a cooling water circulation system to a steam separator to be used as a heat catalyst for generating steam, and at the same time, the fuel cell is cooled by the cooling water which is deprived of heat of vaporization and cooled,
When the power generation operation is stopped, the cooling water cooled by the cooler arranged in the branch circulation system is circulated to the fuel cell to cool the fuel cell at a predetermined temperature reduction rate, so that the fuel cell is mutually cooled through the steam separator. By combining the flow of the three coupled circulation systems with the electric heater and the cooler, the generation of reformed steam and the temperature control in the three states of starting, operating, and stopping the fuel cell are stably performed. It is possible,
Fuel cell performance degradation can be avoided.

〔Example〕

 Hereinafter, the present invention will be described based on examples.

FIG. 1 is a piping diagram of a main part showing an apparatus according to an embodiment of the present invention, and FIG. 2 is a connection diagram of a main part of an electric system thereof, mainly showing a water system part comprising a cooling water circulation system and a steam generation system. Things. In FIG. 1, reference numeral 1 denotes a water-cooled fuel cell, 2 denotes a steam reformer system including a steam reformer 2A, 3 denotes a steam separator containing stored water 8 and high-temperature steam 9, and the amount of stored water 8 is reduced. Is supplied from a condenser or the like (not shown) via a valve 6, and its liquid level is maintained at a predetermined level by a level adjuster 6A.

Reference numeral 10 denotes a cooling water circulation system for circulating the stored water 8 as a cooling medium to the cooler of the fuel cell 1.
Piping 11, circulation pump 12, flow control valve 13,
Fuel cell outlet piping 14, three-way valve 15, and steam separator 3
It is configured as a circulation passage including a pipe 16 communicating with the upper part of the air conditioner.

Reference numeral 21 denotes a heating circulation system for the stored water 8, which is constituted by an electric heater 22, a circulation pump 23, and pipes 21A, 21B, and 21C that form a circulation passage between these and a steam separator.

Reference numeral 30 denotes a branch circulation system including a cooler 32 and a three-way valve type temperature control valve 33, and one of the pipes 31A is switchably connected to the cooling water circulation system 10 through one port B of the three-way valve 15,
The other end is connected to the upper portion of the steam separator 3 through the pipe 31C, and one port B of the three-way valve type temperature control valve 33 is connected to the suction side of the circulation pump 12 through the pipe 31D. In addition, a circulation passage for bypassing the steam separator 3 is formed in the cooling water circulation system 10.

In the embodiment apparatus configured as described above, the pump 23 stores the stored water 8 of the steam separator 3 when the apparatus is started.
And heated by the electric heater 22,
Switching the three-way valve 15 from A to B side to pump the cooling water circulation system 10
12 is driven to circulate through the fuel cell 1 and the branch circulation system 30 using the stored water 8 as a heating medium. At this time, the cooler 32
Valve 32B is closed to stop its cooling function. Since the temperature of the cooling plate of the fuel cell 1 rises as shown by the curve 101 in FIG. 3 with the rise of the temperature of the stored water 8, the temperature control valve 33 is controlled by the fuel cell inlet temperature controller 33A to control the piping 31C. And 31
By controlling the ratio of the amount of water branched to D, the average temperature of the battery can be preheated to, for example, about 130 ° C. before the start of power generation. Note that, in FIG.
Is provided in the stored water 8 of the steam separator 3, the pump 23 can be omitted, and the heating circulation system can be constituted by the water circulation path by the pump 12. On the other hand, the temperature of the stored water of the steam separator 3 is, for example, as shown by a curve 102 in FIG.
Temperature controller 24 up to ° C, pressure regulator above
By controlling the amount of saturated steam 9 generated by controlling the opening of the pressure control valve 5 and 5A, in other words, by controlling the heat of vaporization, for example, 16
Maintained at about 0 ° C., the generated saturated steam is sent to the steam reformer system 2 to perform steam reforming of the raw fuel. Then, when power generation is started in anticipation of generation of reformed gas, the temperature of the cooling plate of the fuel cell 1 rises as shown by a curve 101 due to self-heating, and the operation of starting the water system is completed.

Therefore, the current of the electric heater 22 is cut off, and the circulation pump 23
Is stopped, and the three-way valve 15 is switched from the A to the C side to circulate through the cooling water circulation system 10, so that the heat generated by the power generation of the fuel cell 1 can be used as a heat source to generate saturated steam required for reforming, The fuel cell 1 is cooled by flowing the stored water whose temperature has been reduced by being deprived of the fuel cell as cooling water to the fuel cell, and the power generation operation is performed while maintaining a predetermined operating temperature. The inlet temperature of the cooling water of the fuel cell is maintained at a predetermined temperature by controlling the opening of the pressure regulator 5A and the pressure regulating valve 5 as described above. When the fuel cell load increases,
Since the fuel cell outlet temperature of the cooling water rises, the temperature of the fuel cell itself rises accordingly.

When stopping the power generation operation, after shutting off the reaction gas supplied to the fuel cell, the three-way valve is switched from A to B side,
By opening the cooling water on-off valve 32B of the cooler 32, the temperature of the circulating water passing through the branch circulating system 30 is reduced.
By controlling the cooling water temperature at the fuel cell inlet side to fall at a prescribed cooling rate according to 33, the cooling plate temperature of the cell and the water temperature in the steam separator decrease as shown by curves 111 and 112 in FIG. When the battery inlet temperature has dropped to about 70 ° C. to 80 ° C., the valve 32B is closed to terminate the operation of stopping the cooling water system.

The on / off control of the electric heater 22 is performed by closing the electromagnetic switches 45 and 46 at the time of starting and supplying electric power to, for example, the two electric heaters 22A and 22B from the electric power system side as shown in FIG. When the starting operation of the water system is started, when the reformed gas amount reaches the specified value, the DC switch 43 is closed and the orthogonal transformer 41 is started, and the electronic switches 45 and 46 are opened. , 48 is closed and one electric heater 22A generates heat,
When the reformed gas amount further increases, the electromagnetic switch 49 is closed to cause the other electric heater 22B to generate heat. When the introduction of the specified amount of gas into the fuel cell is completed and the activation of the gas and water systems is completed, the electromagnetic switches 47, 48, and 49 are turned off, the interconnection switch 44 is closed, and power transmission to the power system is started. I do. However, when the fuel cell power generator includes a starting storage battery, this can be used as a power source for the electric heater. The three-way valve type temperature control valve and the three-way valve in the description of the above-described embodiment can be replaced with a system using two two-way valves.

〔The invention's effect〕

As described above, the present invention relates to a fuel cell power generator including a fuel cell, a steam separator for supplying steam to a steam reformer system for raw fuel, and a cooling water circulation system for circulating cooling water therethrough. The steam separator has a heating circulation system that raises the temperature of the stored water to a temperature suitable for starting the fuel cell by an electric heater when the fuel cell is started, and a temperature controller that adjusts the temperature of the stored water. The water circulation system includes a cooling water outlet of the fuel cell, a three-way valve, a steam separator, a pump for cooling water circulation, a cooling water inlet of the fuel cell, and a branch circulation system which is separated from the three-way valve. The branch circulation system has the three-way valve, a cooler that cools the cooling water when the fuel cell is stopped, and a three-way valve-type temperature control valve that is provided for adjusting the temperature of the fuel cell inlet cooling water. Connected in order, One of the cooling water outlets of the three-way valve type temperature control valve is connected to the piping between the three-way valve of the cooling water circulation system and the steam separator, and the other cooling water outlet is connected to the steam separation of the cooling water system. A pipe was connected between the pump and the pump. As a result, the electric heater can be used as a heat source for both steam generation and fuel cell preheating, and the starting temperature of the fuel cell can be controlled by the temperature control valve of the branch circulation system to perform the water-based starting operation. Since the electric power generated by the fuel cell during operation can be used for heating the electric heater, the boiler for steam generation and its piping in the conventional device are not required, so that the configuration of the device can be simplified, and the flow rate of the heating medium can be reduced by turning on the heating medium. The elimination of an increase in the temperature difference of the fuel cell and a decrease in performance due to the problem, which have been a problem with the conventional method of turning off the power, are eliminated, thereby simplifying the start-up of the device efficiently without adversely affecting the performance of the fuel cell. A water-cooled fuel cell power generator can be provided. In addition, when the power generation operation is stopped, cooling can be performed while controlling the cooling water temperature by a cooler and a temperature control valve arranged in the branch circulation system. Can be performed, and the deterioration of the electrode catalyst and the deterioration in performance caused by the problem of the conventional method of stopping the fuel cell at the operating temperature are eliminated, and the advantage that the life of the fuel cell can be extended can be obtained. .

[Brief description of the drawings]

FIGS. 1 and 2 are piping diagrams showing the main parts of the apparatus of the embodiment of the present invention, and connection diagrams of the electric system, FIG. 3 is a temperature characteristic diagram at the time of starting in the embodiment apparatus, and FIG. It is a temperature characteristic figure at the time of a stop in an example device. 1: Water-cooled fuel cell, 2: Steam reformer system, 2A: Steam reformer, 3: Steam separator, 5: Pressure regulating valve, 8: Included water, 9: Saturated steam, 10: Cooling water circulation system, 15: three-way valve, 21: heating circulation system, 22, 22A, 22B: electric heater, 30: branch circulation system, 32: cooler, 33: temperature control valve, 12, 23: circulation pump, 41: orthogonal transformation device, 45, 46, 47, 48, 49: electromagnetic switch, 43: switch, 44: interconnection switch.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yasuki Kubota 1-1-1, Tanabe-Nita, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. (56) References JP-A-60-208067 (JP, A) Showa 63-174281 (JP, A) Actually open Showa 62-191165 (JP, U)

Claims (1)

(57) [Claims] 1. A fuel cell power generator comprising a fuel cell, a steam separator for supplying steam to a steam reformer system for raw fuel, and a cooling water circulation system for circulating cooling water therethrough. Has a heating circulation system that raises the temperature of the stored water to a temperature suitable for starting the fuel cell by an electric heater when the fuel cell is started, and a temperature controller that adjusts the temperature of the stored water. A cooling water outlet of the fuel cell, a three-way valve, a steam separator, a pump for cooling water circulation, a cooling water inlet of the fuel cell, and a branch circulation system branched from the three-way valve; The branch circulation system sequentially connects the three-way valve, a cooler that cools the cooling water when the fuel cell is stopped, and a three-way valve-type temperature control valve that is provided for adjusting the fuel cell inlet cooling water temperature. And the three sides One cooling water outlet of the temperature control valve is connected by piping between the three-way valve of the cooling water circulation system and the steam separator, and the other cooling water outlet is connected to the steam separator of the cooling water system and the pump. A fuel cell power generator characterized by being connected with a pipe between the fuel cell power generator and the fuel cell power generator.