JPH0922713A - Power generating system by fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control system which is for a fuel cell power generation system to be operated with a fuel in liquid state at normal temp. as a raw fuel material and which is capable of supplying a necessary quantity of raw fuel gas with a high response speed from a raw fuel supply source to a fuel cell power-generating plant in quick response to load variation of the fuel cell. SOLUTION: A fuel cell supply source 2 for a fuel in liquid state at normal temp. as a raw fuel material includes a fuel tank 8, which is fitted with a fuel pump 9 and a fuel gasifier 10 to constitute a fuel supplying means, and raw gas supplied from the source to a fuel reformer 3 of a fuel cell power- generating plant 1 through the fuel supplying means as described above is reformed into a hydrogen-rich gas and supplied to the fuel cell 4. In this fuel cell power generation system, fuel demand signals complying with the load variation in the fuel cell obtained by an operation control device 12 of the power-generating plant are sent in a lump to the fuel pump, fuel gasifier, and a fuel flow control valve 6 on the plant side, and upon these signals, raw gas quantity supplied from the source is put in followup control without any response delay to the load variation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-site fuel cell power generation system for generating power by using a hydrocarbon liquid fuel such as butane, ethanol and naphtha as a raw fuel.

[0002]

2. Description of the Related Art Recently, an on-site fuel cell power generation plant has been widely used as a locally dispersed power generation device. The mainstream of such on-site fuel cells are those that use city gas as a raw fuel, but recently, such as butane, ethanol, and naphtha as raw fuels, they are delivered and stored as liquid at room temperature for storage management. Development of on-site fuel cell power generation system using liquid fuel, which is convenient for the user, is also underway.

In this case, the liquid raw fuel stored in the fuel tank is supplied to the fuel cell power plant as a liquid as it is, and is vaporized by the vaporizer built in the reformer (steam reformer) to be gasified. However, in consideration of compatibility with a fuel cell power plant manufactured by using city gas as a raw fuel, a fuel pump and a fuel pump have recently been installed in the fuel tank on the raw fuel supply side. A fuel supply system has been proposed in which a fuel vaporizer is attached and the liquid fuel extracted from the fuel tank is gasified and then supplied to the reformer of the power plant through the gas pipe and the flow control valve, and its development is advanced. Has been.

Here, the fuel vaporizer in which the raw fuel supply source is incorporated has a built-in electric heater, for example, as a vaporization heat source for liquid fuel. A control method is adopted in which the heater is energized and controlled according to the increase and decrease to adjust the amount of heat required for vaporizing the liquid fuel. Regarding the fuel pump, the pump is based on the gas pressure detected in the raw fuel gas supply pipe so that the supply pressure of the raw fuel gas generated by the fuel vaporizer can be kept constant and supplied to the fuel cell power plant. A control method is adopted that adjusts the amount of liquid sent. In other words, in the conventional control method, the raw fuel supply source is separated from the control system of the fuel cell power plant by an independent control system to gasify the liquid raw fuel,
Supply control is performed.

[0005]

By the way, in an on-site fuel cell power generator used as a distributed power generator installed in, for example, an office building, the power demand greatly changes depending on the time zone, and the fuel cell accordingly. The output of fluctuates from moment to moment. Therefore, the control of the fuel cell power generation system is required to be able to sufficiently respond to a large load change.

Considering the above-mentioned fuel cell power generation system using liquid fuel as raw fuel from this point of view, at the raw fuel supply source, the liquid fuel extracted from the fuel tank is vaporized, and then the fuel cell power plant through the gas pipeline. However, the delay in following the supply of raw fuel to the change in fuel demand in the fuel cell due to load fluctuations is a problem. In particular, in the conventional control method for the fuel pump and the fuel carburetor, which are the fuel supply means of the raw fuel supply source, a large delay occurs in the response speed with respect to the load change, which causes the fuel cell power plant to have a large load change. The problem arises that there is an excess or deficiency in the supply amount of raw fuel gas, and stable operation cannot be performed.

The present invention has been made in view of the above points, and an object of the present invention is to provide a fuel cell power generation system using a liquid fuel at room temperature as a raw fuel, in order to quickly respond to load fluctuations of the fuel cell. It is an object of the present invention to provide a fuel cell power generation system capable of supplying a required amount of raw fuel gas from a fuel supply source to a fuel cell power generation plant at a high response speed.

[0008]

In order to achieve the above object, according to the present invention, a fuel demand signal corresponding to a load change of a fuel cell is sent to a fuel supply means of a raw fuel supply source, and the fuel demand signal is sent. Based on the above, the amount of raw fuel gas sent from the raw fuel supply source is controlled to follow the load fluctuation. Here, the fuel demand signal is implemented using a signal corresponding to the output current of the fuel cell or a signal corresponding to the control signal of the fuel flow control valve provided on the reformer inlet side of the fuel cell power plant. be able to.

[0009]

With the above control method, the followability of the raw fuel supply source to the load fluctuation of the fuel cell is significantly improved. That is, when the power demand for the fuel cell power plant fluctuates, the fuel demand amount to be supplied to the fuel cell is calculated based on the load command given to the power generation output setting device and the output current of the fuel cell, and the fuel demand obtained here is calculated. The signal is immediately transmitted to the source of raw fuel to control the fuel pump and the fuel carburetor feedforward. As a result, the raw fuel supply source is ready to generate a sufficient amount of raw fuel gas at a fast response speed and to supply it to the fuel cell power plant in a stable manner without a large follow-up delay. You will be able to respond quickly enough.

In this case, as the fuel demand signal transmitted to the raw fuel supply source side, in addition to the signal corresponding to the output current of the fuel cell, an existing fuel supply signal provided on the inlet side of the reformer in the fuel cell power plant is used. The control signal given to the fuel flow control valve can be used as it is.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a fuel cell power plant, 2 is a raw fuel supply source for storing and supplying liquid fuel such as butane, and as is well known, the fuel cell power plant 1 converts the raw fuel gas into a hydrogen-rich gas. Quality reformer 3, fuel cell 4, inverter 5 for converting DC output of fuel cell to AC
Etc. In addition, 6 is a fuel flow rate control valve provided on the inlet side of the reformer 3, and 7 is a CT for detecting the output current of the fuel cell.
(Current transformer). On the other hand, in the raw fuel supply source 2, a fuel pump 8 and a fuel vaporizer 10 are attached to a fuel tank 8 that stores liquid fuel at room temperature, and the liquid fuel extracted from the fuel tank 8 is gasified by heating with a heater. After that, it is supplied to the reformer 3 of the fuel cell power plant 1.
In addition, 9a is an operation controller of the fuel pump 9, 10a is an electrothermal heater as a vaporization heat source built in the fuel vaporizer 10, and 1a.
Reference numeral 0b is a controller that controls the amount of heat generated by the heater 10a.

In such a fuel cell power generation system, as is well known, the liquid fuel extracted from the fuel tank 8 is gasified by the fuel vaporizer 10 and then the reformer 3 of the fuel cell power plant.
The hydrogen-rich reformed gas reformed here is supplied to the fuel cell 4 to generate electric power, and the generated output is converted into alternating current by the inverter 5 to supply power to the load 11. In this case, in order to improve the responsiveness of the raw fuel supply to the load fluctuation of the fuel cell, in the embodiment of the present invention, the fuel demand signal obtained by the operation control device 12 of the fuel cell power plant 2 is used as the fuel flow control valve. 6, the fuel pump 9 of the raw fuel supply source 2,
The signals are collectively transmitted to the controllers 9a and 10b of the fuel vaporizer 10, and the fuel flow rate control valve 6, the fuel pump 9, and the fuel vaporizer 10 are feedforward-controlled based on the fuel demand signal.

Here, the operation control device 12 includes a controller with a built-in microcomputer, and the output current value of the fuel cell detected by CT7 (a value obtained by adding the current consumed by the auxiliary equipment of the power plant to the load current), and Based on the load command corresponding to the increase / decrease of the load 11 supplied with power from the fuel cell, the supply amount of the raw fuel gas required to obtain the power generation output corresponding to the power demand at that time is calculated to obtain the fuel demand signal. obtain.

By supplying the raw fuel gas from the raw fuel supply source 2 to the fuel cell power generation plant 1 using the control system constructed as described above, even if a large load fluctuation occurs in the fuel cell, It has been confirmed from the results of the actual machine test that the supply source 2 can gasify an appropriate amount of the liquid raw fuel commensurate with the load fluctuation and stably supply it to the reformer 3 without any follow-up delay. The response speed of the control to the load fluctuation in the entire fuel cell power generation system including is improved.

[0015]

As described above, according to the present invention, the fuel supply means in which the fuel pump and the fuel carburetor are combined with the raw fuel supply source using the liquid fuel at room temperature as the raw fuel, In a fuel cell power generation system for generating power by reforming a raw fuel gas supplied from a raw fuel supply source through a fuel supply means into a hydrogen-rich gas and then supplying the fuel cell with power,
The fuel demand signal corresponding to the load fluctuation of the fuel cell is sent to the fuel supply means of the raw fuel supply source, and based on this fuel demand signal, the amount of raw fuel gas sent from the raw fuel supply source is controlled to follow the load fluctuation. As a result, even with a large load change, the amount of raw fuel commensurate with the load change can be supplied to the reformer of the fuel cell power plant at a fast response speed.

As a result, in addition to the use of city gas, natural gas, etc. as the raw fuel for the on-site fuel cell power generation system manufactured in the distributed power generator, the raw fuel provided with the vaporizer for liquid fuel. By replacing it with a supply source, liquid fuel at room temperature such as butane, methanol, and naphtha can be operated as a raw fuel without any problem. For example, the flexibility of selecting the type of raw fuel used in the fuel cell power generation system is increased. There is also the advantage of expansion.

[Brief description of drawings]

FIG. 1 is a system diagram of a fuel cell power generation system according to an embodiment of the present invention.

[Explanation of symbols]

 1 Fuel Cell Power Plant 2 Raw Fuel Supply Source 3 Reformer 4 Fuel Cell 5 Inverter 6 Fuel Flow Control Valve 7 CT (Output Current Detector) 8 Fuel Tank 9 Fuel Pump 10 Fuel Vaporizer 11 Load 12 Operation Control Device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Isao Nakagawa 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Fuji Electric Co., Ltd. (72) Inventor Takashi Watanabe 1-Tanabe Shinagawa, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture No. 1 inside Fuji Electric Co., Ltd.

Claims (3)

[Claims] 1. A fuel cell power generation system using a liquid fuel at room temperature as a raw fuel, comprising a fuel supply means combining a fuel pump and a fuel vaporizer as a raw fuel supply source, and supplying the raw fuel through the fuel supply means. In the case of reforming the raw fuel gas supplied from the fuel supply source to a hydrogen-rich gas and then supplying it to the fuel cell to generate electricity, the fuel demand signal corresponding to the load fluctuation of the fuel cell is used as the fuel of the raw fuel supply source. Send to supply means,
A fuel cell power generation system characterized in that the amount of raw fuel gas sent from a raw fuel supply source is controlled so as to follow a load change based on the fuel demand signal. 2. The fuel cell power generation system according to claim 1, wherein the fuel demand signal is a signal corresponding to the output current of the fuel cell. 3. The fuel cell power generation system according to claim 1, wherein the fuel demand signal is a signal corresponding to a control signal of a fuel flow control valve provided on the reformer inlet side of the fuel cell power generation plant. Fuel cell power generation system.