JPH03266366A - Control unit of fuel cell generating system - Google Patents

Abstract

PURPOSE:To keep a supplying gas constantly at a satisfactory pressure by determining the standard set flow rate of the supplying gas on the basis of a cell current or load, and adding a correction quantity based on the deviation between the pressure set value and detected value in the upper stream part of the starting gas to the set flow rate to perform control. CONSTITUTION:The flow rate of a supplying gas is controlled by a supplying gas flow rate regulating valve 1 controlled by a controller 12. The controller 12 is operated by comparing the detected value by a flow rate detector 2 with a set standard quantity. The set standard value is the addition of a correction flow rate (j) determined through a controller 9 from the deviation between the detected value (e) detected through a pressure detector 8 in the upper stream part from a battery of the starting gas and a set value (f) to a standard set flow rate (i) set through a function generator 10 on the basis of a cell current (h) or load. Hence, the starting gas is increased and decreased prior to the increase and decrease of the current or load, so that the starting gas can be stably supplied.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a fuel cell power generation system comprising a fuel cell and a reformer. The present invention relates to a control device for a fuel cell power generation system in which the controllability of the pressure in a reforming system is improved to improve load followability.

(Conventional technology) Fuel cell power generation systems are highly efficient, non-polluting, and low-noise.
It is also said to be a power generation system with excellent load followability.

This system has a reformer that generates the hydrogen gas necessary for the electrochemical reaction in the fuel cell from raw material gases such as natural gas and naphtha. Control was performed to maintain an appropriate representative pressure in the fuel reforming system.

FIG. 4 shows an example of a conventional configuration of a control device for a fuel cell power generation system related to this.

In the figure, 1 is a raw gas flow rate control valve, 2 is a pretreatment device such as a hydrodesulfurizer, 3 is a reformer, 4 is a high temperature shift converter, 5 is a low temperature shift converter, 6 is a steam separator, and 7 is a battery fuel electrode. A fuel flow control valve, and 8 a pressure detector. In this conventional example, a detector 8 detects the pressure at the outlet of the steam separator, and a regulator 9 generates an opening command d based on a deviation C between the detected value a and a set value S. In this conventional example, the raw material gas is appropriately supplied so as to maintain the separator outlet pressure at the set pressure in response to an increase or decrease in the fuel flow rate supplied to the fuel cell. In this case, since the raw material gas flow rate control valve tries to control the pressure in a part separated from many devices such as a pre-processing device and a reforming device, the controllability is not sufficient and good stability and followability cannot necessarily be obtained. It wasn't.

FIG. 5 shows a second conventional configuration example of a control device for a fuel cell power generation system according to the present invention, and the same elements as in FIG. 4 are given the same reference numerals. In this conventional example,
4, the pressure in the upstream part of the reformer, which is easier to control, is detected by the detector 8, and based on the deviation g between the detected value e and its set value f, the regulator 9 controls the feed gas The configuration is such that an opening command d is given to the flow rate control valve 1. However, in a control device having such a configuration, although the pressure itself can be controlled well, the primary side pressure of the regulating valve 7 cannot be properly controlled by the downstream flow regulating valve 7 to properly supply fuel to the fuel cell. In order to maintain this, high controllability is required for the pressure control upstream of the reformer, and this controllability is not necessarily satisfactory when there is a sudden load change.

(Problems to be Solved by the Invention) As described above, in conventional fuel cell power generation plants, the pressure in the fuel reforming system fluctuates in the event of sudden load changes, etc., resulting in a stable fuel supply to the fuel cell. There have been problems such as a large pressure difference (hereinafter referred to as internal and external pressure difference) between the reforming side and the combustion side of the reformer. The present invention was made to solve the above-mentioned problems, and it can stably supply fuel gas to the fuel cell by effectively suppressing pressure fluctuations in the fuel reforming system even in the face of sudden load fluctuations. It is an object of the present invention to provide a control device for a fuel cell power generation system that supplies fuel to the fuel cell and satisfactorily suppresses the generation of differential pressure between the inside and outside of a reformer.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention determines a reference flow rate of the raw material gas from the battery current and load command, and uses this to determine the flow rate of the reaction gas upstream of the reformer. A set flow rate of the source gas is generated by adding a corrected flow rate based on a deviation signal between the pressure set value and the detected value, and the flow rate is controlled to follow this set value.

(Function) Therefore, according to the present invention, when the cell current or load increases in the fuel cell power generation system, the supply amount of the raw material gas is increased in advance, which reduces the pressure in the fuel reforming system. An action is taken to prevent this. Conversely, when the load decreases, the raw material gas is narrowed down in advance.
It has the effect of suppressing pressure rise in the reforming system.

(Example) Examples of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a control device for a fuel cell power generation system according to the present invention, and the same parts as in FIGS. 4 and 5 are denoted by the same reference numerals, and the explanation thereof will be omitted.

In this embodiment, in contrast to the conventional example shown in FIG.
and a pressure deviation signal g to obtain a corrected flow rate j, and the regulator 12 calculates the corrected flow rate j from the sum signal of these signals and the deviation m between the flow rate detection value A by the detector 11.
The configuration is such that an opening degree command d is generated.

Next, the operation of this embodiment will be explained. For example, time t
The case where the load or battery current increases from t2 to t2 will be explained using FIG. In response to this increase in load,
In the conventional configuration shown in Fig. 5, the raw material gas flow rate is increased by a closed loop control configuration based on the gas pressure upstream of the reformer, so the increase in the raw material gas flow rate is slow as at F2, and therefore the pressure decrease is also as slow as at P2. It grows like that. On the other hand, according to the embodiment shown in FIG. 1, the raw material gas is increased in advance in accordance with the increase in the load and battery current signal, so this response becomes more responsive as shown in Fl, and therefore The drop in the pressure mentioned above is also well suppressed as shown by Pl.

Therefore, according to this embodiment, by changing the raw material gas in advance, in order to suppress transient pressure fluctuations in the fuel reforming system, the pressure can be maintained appropriately even in response to sudden load changes.
It becomes possible to efficiently supply fuel gas to the battery.

FIG. 3 is a block diagram showing another embodiment of the present invention.

This embodiment has a configuration in which a leading element or a lagging element computing unit 13 is added to the raw material gas standard set flow rate 1 of the embodiment shown in FIG. Here, 13 is, for example, equation (1) or (2)
It is given by Eq.

10T2S...(1)(
1+TS)/11+T3S)...(2
) Compared to the embodiment shown in FIG. 1, this embodiment changes the raw material gas more proactively to suppress pressure fluctuations in the fuel reforming system. It is clear that the same functions and effects as in the above embodiment can be obtained.

In the above embodiments, the battery current and load are used as signals, but the same operation and effect can be obtained even if these command values are set to h.

[Effects of the Invention] As explained above, according to the present invention, since the raw material gas flow rate is controlled in advance when the load changes, the pressure in the fuel reforming system is always maintained at an appropriate level, and therefore the pressure to the fuel cell is improved. At the same time as maintaining a good fuel supply, it is possible to suppress the generation of differential pressure between the inside and outside of the reformer, improving the plant's ability to follow load and reducing stress on the reformer. .

[Brief explanation of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of a control device for a fuel cell power generation system according to the present invention, FIG. 2 is an explanatory diagram showing the difference in operation between the embodiment of FIG. 1 and a conventional example, and FIG. 3 teeth,
A configuration block diagram showing another embodiment of the control device for the fuel cell power generation system according to the present invention, FIG. 4 is a configuration block diagram showing a conventional example of the control device for the fuel cell power generation system, and FIG. 5 shows another example of the conventional control device. FIG. 1... Raw material gas flow rate control valve 2... Pretreatment device 3... Reformer 4...
High temperature shift converter 5...Low temperature shift converter 6...7 Palator 7...Battery fuel electrode fuel flow control valve

Claims (1)

[Claims] A reformer that reforms raw material gas to produce hydrogen-rich reformed gas, the reformed gas obtained by this reformer is used as fuel gas to be sent to the fuel electrode, and the oxidant gas is sent to the oxidizer electrode. The flow rate of the raw material gas is controlled based on the deviation between the pressure setting value and the detected value in the upstream part of the reaction gas side of the reformer. In a fuel cell power generation system that performs control, the standard set flow rate of the raw material gas is determined based on the cell current or load, and a correction value is given based on the pressure deviation to generate the set flow rate of the raw material gas. A control device for a fuel cell power generation system characterized by performing control.