JP2002334710A - Load-following fuel cell power generation system - Google Patents

Abstract

(57) [Abstract] [Problem] To be able to follow fast fluctuation of load power,
It also prevents power loss. SOLUTION: A fuel cell stack 22 is connected to a desulfurizer 21, an inverter 23 is connected to the fuel cell stack 22, and a sodium sulfur battery 25 is connected between the fuel cell stack 22 and the inverter 23 via a bidirectional converter 24. And a heat exchanger 26 connected to the fuel cell stack 22 by a cooling water pipe 29.
Is provided, and the heater 27 is connected to the heat exchanger 26 by a heat transfer medium tube 30, and a water heater 28 connected to the heat exchanger 26 by a heat transfer medium tube 31 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load-following fuel cell power generation system in which output power can follow load power.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram showing a conventional fuel cell power generation system. As shown in the figure, a fuel cell stack 2 is connected to a fuel processor 1, an inverter 3 is connected to the fuel cell stack 2, and a water heater 4 is connected to the fuel cell stack 2.
Is connected.

In this fuel cell power generation system, when fuel gas is supplied to the fuel processor 1, the fuel gas is processed by the fuel processor 1, and then the fuel cell stack 2
The fuel cell stack 2 generates power by the reaction between the fuel gas and oxygen in the air, and the generated DC output power is converted into AC power by the inverter 3, and the AC power is supplied to the load. With respect to the fluctuation of the load power, the output power of the fuel cell stack 2 is changed by controlling the flow rate of the fuel gas supplied to the fuel cell stack 2 and the flow rate of the cell reaction air. Heat is generated when power is generated in the fuel cell stack 2, but exhaust heat of the fuel cell stack 2 is supplied to the water heater 4.

FIG. 9 is a block diagram showing a conventional sodium-sulfur battery system. As shown in the figure, a sodium-sulfur battery 13 is connected to a commercial AC power system 11 via a power converter 12, and a heater 14 for heating the sodium-sulfur battery 13 is provided.

In the sodium-sulfur battery system, when charging the sodium-sulfur battery 13, DC power is supplied from the commercial AC power system 11 to the sodium-sulfur battery 13 via the power converter 12, and the sodium-sulfur battery 1 is charged.
During the discharge of AC power, AC power is supplied from the sodium-sulfur battery 13 to the load via the power converter 12. The reaction at the time of charging the sodium-sulfur battery 13 is an endothermic reaction.
Keep at a temperature of 0 ° C.

[0006]

However, in the fuel cell power generation system shown in FIG. 8, since the responsiveness of temperature control of the fuel processor 1 and the fuel cell stack 2 is slow, the fuel is not affected by a change in load power. The output power of the battery stack 2 fluctuates slowly and cannot follow fast fluctuations of the load power.

In the sodium-yellow battery system shown in FIG. 9, since the sodium-sulfur battery 13 is heated using the heater 14, that is, the sodium-sulfur battery 13 is heated using electric power. Power loss occurs.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and provides a load-following fuel cell power generation system that can follow a rapid change in load power and does not cause power loss. The purpose is to do.

[0009]

According to the present invention, there is provided a fuel cell power generation system having a fuel cell stack and an inverter, wherein a bidirectional converter is provided between the fuel cell stack and the inverter. To connect the sodium-sulfur battery and exhaust heat from the fuel cell stack to the sodium-sulfur battery.

In this case, the exhaust heat from the fuel cell stack may be supplied to the sodium sulfur battery via a heat exchanger.

[0011]

FIG. 1 is a diagram showing a part of a load-following fuel cell power generation system of an internal reforming type according to the present invention.
FIG. 2 is a diagram showing a part of the load following fuel cell power generation system shown in FIG. 1. As shown in the figure, a fuel cell stack 22 having a fuel electrode 22a and an air electrode 22b is connected to a desulfurizer 21 as a fuel processing device, an inverter 23 is connected to the fuel cell stack 22, and the fuel cell stack 22 and the inverter 23 Is connected to a sodium-sulfur battery 25 via a bidirectional converter 24.
2 is provided with a heat exchanger 26 connected by a cooling water pipe 29, a heater 27 for heating the sodium-sulfur battery 25 is provided, and the heater 27 is connected to the heat exchanger 26 by a heat transfer medium pipe 30 to exchange heat. Heat transfer medium tube 3 to vessel 26
A hot water supply 28 connected by 1 is provided.

This load following type fuel cell power generation system has
When the fuel gas is supplied to the desulfurizer 21,
Fuel cell stack after the gas is processed by the desulfurizer 21
The fuel cell stack 22 is supplied with fuel gas and
Generates power by reacting with oxygen in the air, and outputs the generated DC
The power is converted into AC power by the inverter 23,
Power is supplied to the load. In this case, the fuel cell stack 2
The control of (2) is the fuel gas supply flow rate, reforming steam flow rate and
This is performed by controlling the flow rate of the battery reaction air.
Then, the output power of the fuel cell stack 22 is represented by P₁(K
W), the input power of the inverter 23 is P₂(KW), load
The power is ρP₂(KW) (ρ is the conversion effect of the inverter 23)
Rate), P₁> P₂In the case of, as shown in FIG.
And power (P ₁−P₂) To charge the sodium-sulfur battery 25
And input power P₂Is input to the inverter 23. Ma
T, P₂> P₁In the case of, as shown in FIG.
(P₂−P₁) Is discharged from the sodium-sulfur battery 25,
Output power P of fuel cell stack 22₁Input power
Force P₂Is input to the inverter 23. As a result, FIG.
As shown, during a short time t, the load power ρP₂Is fluctuating
When the power is increased by a (kW), the output power P₁Is a
/ T, the output power P₁
Time T longer than time t to increase
Is required, the power of the difference
Supplied by the discharge of the sulfur battery 25, the output of the inverter 23
The output power of the load-following fuel cell power generation system
Load power ρP ₂It changes following. Also shown in FIG.
Thus, during the time t, the load power ρP₂Is only variable power a
When it decreases, the output power P₁Changes with the slope of a / T
Even if it is, that is, the output power P₁Only the variable power a
Even if it takes time T to decrease, the difference indicated by the oblique line
Is charged to the sodium-sulfur battery 25,
Output of the inverter 23, that is, a load-following fuel cell power generation system
The output power of the system is the load power ρP₂It changes following.
In addition, a heat exchanger is provided by exhaust heat from the fuel cell stack 22.
The heater 27 can be heated via 26. sand
That is, the exhaust heat from the fuel cell stack 22 is
Is supplied to the sodium-sulfur battery 25. Also,
The heat exchanger 26 is discharged by the exhaust heat from the fuel cell stack 22.
The water heater 28 can be heated through.

In such a load-following fuel cell power generation system, when the load power ρP ₂ changes by the fluctuating power a during a short time t, it takes time t to change the output power P ₁ by the fluctuating power a. even take longer T than the discharge of the sodium-sulfur battery 25, the charge, since the output that is the output power of the load-following fuel cell power generation system of the inverter 23 changes to follow the load power RoP _2, load power Can follow the rapid fluctuation of Further, since the exhaust heat from the fuel cell stack 22 is supplied to the sodium-sulfur battery 25, there is no need to heat the sodium-sulfur battery 25 using electric power, so that no power loss occurs. Also, the fuel cell stack 2
Since the waste heat from the fuel cell stack 2 is supplied to the sodium-sulfur battery 25 via the heat exchanger 26, it is necessary to connect the water heater 28 and the like to the heat exchanger 26 to effectively use the waste heat from the fuel cell stack 22. Can be.

FIG. 7 is a view showing a part of an external reforming type load following fuel cell power generation system according to the present invention. As shown in the drawing, the reformer 42 is connected to the desulfurizer 41, the CO converter 43 is connected to the reformer 42, the fuel cell stack 45 is connected to the CO converter 43, and the fuel cell stack 45 is connected.
Is connected to the fuel cell stack 45 and the inverter 23 via a bidirectional converter 24. The desulfurizer 41, the reformer 42, and the CO converter 43 constitute a fuel processor 44.

In the above embodiment, the exhaust heat from the fuel cell stack 22 is supplied to the sodium-sulfur battery 25 via the heat exchanger 26, but the exhaust heat from the fuel cell stack is directly supplied to the sodium-sulfur battery. May be supplied.
Further, in the above embodiment, the water heater 28 is connected to the heat exchanger 26, but an absorption refrigerator or the like may be connected to the heat exchanger.

[0016]

According to the load-following fuel cell power generation system of the present invention, the output power of the load-following fuel cell power generation system can be changed by following the load power by discharging and charging the sodium-sulfur battery. From this, it is possible to follow fast fluctuations in load power, and there is no need to use power to heat the sodium-sulfur battery,
No power loss occurs.

Further, when waste heat from the fuel cell stack is supplied to the sodium-sulfur battery via the heat exchanger,
By connecting a water heater or the like to the heat exchanger, the exhaust heat from the fuel cell stack can be effectively used.

[Brief description of the drawings]

FIG. 1 is a diagram showing an internal reforming type load following fuel cell power generation system according to the present invention.

FIG. 2 is a diagram showing a part of the load following fuel cell power generation system shown in FIG.

FIG. 3 is an operation explanatory diagram of the load following fuel cell power generation system shown in FIGS. 1 and 2;

FIG. 4 is an operation explanatory view of the load following fuel cell power generation system shown in FIGS. 1 and 2;

FIG. 5 is a graph for explaining the operation of the load following fuel cell power generation system shown in FIGS. 1 and 2;

FIG. 6 is a graph for explaining the operation of the load following fuel cell power generation system shown in FIGS. 1 and 2;

FIG. 7 is a diagram showing a part of an external reforming load-following fuel cell power generation system according to the present invention.

FIG. 8 is a configuration diagram showing a conventional fuel cell power generation system.

FIG. 9 is a configuration diagram showing a conventional sodium-sulfur battery system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 ... Desulfurizer 22 ... Fuel cell stack 23 ... Inverter 24 ... Bidirectional converter 25 ... Sodium sulfur battery 26 ... Heat exchanger 27 ... Heater 44 ... Fuel processor 45 ... Fuel cell stack

Continued on the front page F term (reference) 5H027 AA02 BA01 BA02 BA17 DD00 DD03 DD06 5H031 AA05 KK08

Claims (2)

[Claims] In a fuel cell power generation system having a fuel cell stack and an inverter, a sodium-sulfur battery is connected between the fuel cell stack and the inverter via a bidirectional converter, and the fuel cell stack is discharged from the fuel cell stack. A load-following fuel cell power generation system that supplies heat to the sodium-sulfur battery. 2. The load-following fuel cell power generation system according to claim 1, wherein the exhaust heat from the fuel cell stack is supplied to the sodium-sulfur battery via a heat exchanger.