JPH03276576A - Pressure type fuel cell power generating system - Google Patents

Abstract

PURPOSE:To improve the energy utilization factor by providing an oxygen permeating film type separating device separating the oxygen-enriched gas from the off-air bn the outlet side of an air chamber. CONSTITUTION:A separating device 21 is constituted of a pressure container partitioned into an off-air chamber 21B and an oxygen-enriched gas chamber 21C by an oxygen permeating film 21A made of polyimide, the oxygen in the off-air 5C guided into the off-air chamber 21B on the high gas pressure side permeates the permeating film 21A via the pressure difference applied to the permeating film 21A without requiring special power, it is separately recovered to the oxygen-enriched gas chamber 21C side which is the low-gas pressure side, and the residual nitrogen-rich exhaust gas 5D is decompressed by a decompressor 6A then discharged to the outside of the system. The recovered oxygen- enriched gas 25 contains oxygen 90% or above, and it is fed to the intake port side of an air compressor 2 via an oxygen adding passage 24. The energy utilization factor is improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a pressurized fuel cell power generation system using a reformed gas 2 of a hydrocarbon fuel and oxygen in the air as active materials for a power generation reaction, especially in the air. Concerning oxygen processing structure.

[Conventional technology]

FIG. 3 is a simplified system configuration diagram of a conventional pressurized phosphorus eR type fuel cell power generation system.

In the figure, a pressurized fuel cell (main body) 1 is housed in a pressure vessel (not shown), and a stacked structure of a plurality of single cells (
stack). Each cell has 12 F on both sides of a matrix 11 soaked in phosphoric acid as an electrolyte!
A fuel gas chamber 14 is formed on the anti-matrix side of the combustion chamber side 12 by a ribbed electrode base material or a ribbed separate plate. At the same time, an air chamber 15 is formed on the opposite side of the air electrode 13 from the matrix.

2 is an air compressor that supplies pressurized air as an oxidizing agent to the air chamber 15, and the atmospheric pressure gauge 5 is set to, for example, 4/, -nG.
The pressurized air 5A is supplied to the air chamber 15 with a knife mouth pressure of about 5A. In addition, the fuel reformer 3 performs a steam reforming reaction, which is an endothermic reaction, using the combustion heat of the burner 18 as a heat source, and uses a mixed gas of methanol and water, or natural gas and steam as the reforming raw material 4. The mixed gas is heated in the raw material superheating tube 16 to a temperature suitable for reforming reaction, and the reforming reaction tube 17f contains all the reforming catalyst! : Through the passage K, hydrogen-rich reformed gas 4AKf is exchanged and supplied to the fuel gas chamber 14 of the fuel cell 1.

The pressure of the reformed gas 4A supplied to the fuel gas chamber 14 and the pressurized air 5A supplied to the air chamber 15 is determined by, for example, a pressure reduction system provided in the outlet side pipes 14A and 15A of each chamber, including a pressure reduction chamber or a flow rate control 9P. 6F (fuel gas side), 6A (
The pressure difference across the matrix 11 is controlled to be close to zero. As a result, the hydrogen in the reformed gas diffuses into both electrodes 12 and 1, respectively.
Oxygen in the pressurized air then comes into contact with the electrocatalyst particles wetted with resin, resulting in direct power generation based on an electrochemical reaction. The generated power is subjected to, for example, constant voltage control by the power converter 9 and is supplied to the multiplication part load 10 . However, the fI50 (XI of oxygen in the pressurized air at the air electrode 13 is consumed and 9 off air 5B
is discharged to the outside via the pressure reducer 6At-, and the fuel electrode 12
After the oxygen is consumed, the unused hydrogen contained in the off gas 4BIC is sent to the burner 18 via the pressure reducer 6F, and the combustion support air 7 is sent to the burner 18 by the combustion support air blower 8.
It is mixed with and combusted and used as a heat source necessary for the steam reforming reaction. Incidentally, if the combustion heat of residual hydrogen in the off-gas 4B is insufficient to cover the reaction heat 'ft, a part of the reformed raw material is supplied to the burner 18 as auxiliary fuel.

[Problem to be solved by the invention]

In the conventional device button configured as described above, when trying to improve the efficiency of the power generation reaction of the fuel cell 1, hydrogen and 11! ar, it is an electrochemical reaction part! The gas phase is quickly supplied to the interface between the pole and the matrix.
It is required to activate the power generation reaction at the three-phase interface consisting of a liquid phase and a solid phase. The supply of reactant gas to this three-phase interface depends on the air flow and the gas spread rate at the fuel electrode. In particular, the reaction rate is determined by the gas diffusion rate K or oxygen, which is slower than hydrogen. As a countermeasure against the gas diffusion rate in the conventional device, there is a method of increasing the pressure of the reaction gas to about 4 to 9/iG, and a method of increasing the hydrogen consumption rate of the fuel gas (also called fuel utilization rate) of 70 to 5O91. On the other hand, it includes a method of suppressing oxygen consumption in pressurized air to about 5O91, thereby increasing the lower limit of oxygen concentration.However, in order to further improve the efficiency of the power generation reaction of fuel cells, Gas pressure 4#/mG
If it is increased above, the pressure vessel housing the fuel cell 1, the fuel reformer 3, and the air pressure J1! In the 9th century, when all the equipment and piping became high pressure, the equipment became larger and more powerful.
A problem arises in that it causes long-term disadvantages.In addition, if the oxygen consumption rate of the reaction air is further lowered, the amount of air used for one change will increase, resulting in an increase in the size of the 9-air compressor, and the compression speed will increase. In addition to increasing the loss of auxiliary machinery required, the problem arises that unused off-air containing a large amount of oxygen is discarded without being used, and the energy consumption of the power generation system as a whole is reduced by half. A problem arises in that the value decreases.

An object of the present invention is to improve the power generation efficiency of a fuel cell and the energy utilization rate of the power generation system as a whole without reducing the oxygen consumption rate when the reaction gas pressure is increased.

[Measures to solve the problem] In order to solve the above problem, according to the present invention, a fuel electrode and an air electrode that sandwich a matrix, and a fuel gas chamber and an air chamber that supply a reaction gas to both electrodes are provided. a fuel cell, a fuel reformer that supplies hydrogen-rich reformed gas to the fuel gas chamber, and an air compressor that supplies pressurized air to the air chamber; An fIR elementary permeable membrane type that separates A12 Sofu Kita gas from off 3 gas on the outlet side of the air chamber in which combustion supporting air is supplied to the burner of the fuel reformer to serve as a heat source for the reforming reaction. A multi-layer device is provided, and an oxygen addition passage for the reaction air is provided on the air suction side of the air compressor to supply the separated so-called acid-enriched gas. This shall include at least 10,000 oxygen containing passages for supplying oxygen to the suction side of the low blower blower of the burner of the oxidized gas fuel reformer.

[Effect]

In the configuration of this invention, an oxygen permeation type separator is installed on the outlet side of the air chamber via a '4A water container.The off-g! This provides the ability to separate oxygen contained in the air and easily recover it as oxygen monoxide gas.

Therefore, by providing an additional passage to supply the recovered oxygen-enriched gas to the air suction side of the air compressor, it is possible to significantly increase the oxygen concentration in the pressurized air produced by the air compressor compared to conventional methods. This makes it possible to increase the diffusion rate of the element in the air electrode and improve the power generation performance of the fuel cell. Providing an additional passage for supplying air to the air suction side increases the combustion efficiency of off-gas and auxiliary fuel in the reformer burner, stabilizes combustion, and allows the combustion-supporting air blower to have a small capacity. By doing so, it is possible to obtain functions that improve the power generation efficiency of the power generation system as a whole.

Cjj! Example] The present invention will be explained below based on an embodiment.

FIG. 1 is a simplified system configuration diagram of a pressurized fuel cell power generation system fcm according to an embodiment of the present invention. Hereinafter, the same reference numerals will be used for the same parts as in the conventional device, and detailed explanation will be omitted. In the figure, in the air chamber 15 of the fuel cell 1, a radiator 22 is provided on the outlet side piping 15A of off-air 5B, and by cooling the off-air 5B containing generated water accompanying the power generation reaction, the generated water 1 -*Shrink and separate. The condensed water is recovered by the condenser 23, becomes dry off-air 5C, and is supplied to an oxygen permeable membrane type separator (t21).
The acid in the off-air 5C, which is divided into an off-air chamber 21B and an oxygen-enriched gas chamber 21C by protection 21A, and the off-nitrogen chamber 21B on the high gas pressure side of the pressure vessel: I
g is completely permeated through the permeable membrane without the need for special power due to the differential pressure across the permeable membrane 21A, and becomes r11 on the low gas pressure side.
The enriched gas N21C is separated and recovered, and the remaining nitrogen-rich waste gas 5D is depressurized with a vacuum 66A and then discharged to the outside of the system. - 10,000, the recovered oxygen-enriched gas 25 contains more than 90% oxygen, so #! The air 5 and the oxygen-enriched gas 257 are supplied to the suction port side of the air compressor 2 through the element addition passage 24t, and are subjected to wall pressure in the air compressor 2. As a result, the pressurized air 30 compressed to 4#/cIItG6 degrees has its a!
The concentration of two elements is high, so air electrode 1 of fuel meter 1
Since the diffusion rate in 3 is the same as above, it can be activated by electrochemical reaction at the three-phase interface.

Methods for completely separating oxygen and nitrogen include cooling separation method, P
S A (Pressure SwingAdoso
rpt, i.

n) method is also known, but although it can obtain high R degree acid, it has the disadvantage of high operating cost. Utilizing the high pressure state of 4 H/cr/l G, oxygen can be separated and recovered by pressure difference.
It is also possible to perform all heat recovery by replacing the radiator with a heat exchanger, which provides the advantage of lower operating costs.

FIG. 2 is a system configuration diagram showing a different embodiment of the present invention.
The rR hydrogenation gas 25 separated in step 1 is supplied via the oxygen addition passage 35 to the suction port side of the combustion support air blower 8 that supplies combustion support air to the reformer burner IENC, and the combustion support air 7 and oxygen enriched The difference is that the gas 25 is also supplied to the reformer burner 18), and by effectively utilizing oxygen in the off-air to increase the oxygen content in the combustion-supporting air, The combustion efficiency of the off-gas 4B or the auxiliary fuel is improved, and the combustion condition of one burner can be stabilized. However, it is also possible to adjust the discharge amount of the combustion-supporting two-gas blower 8 to match the amount of recovered oxygen-enriched gas 25. This has the advantage of making the blower 8 smaller and reducing its auxiliary loss. You can also get

〔Effect of the invention〕

As described above, the present invention is constructed so that an oxygen permeation type separation device is provided on the air chamber outlet side of a pressurized fuel cell. As a result, by utilizing the high-pressure state of the off-air, it is possible to separate the unused bush material contained in about half of the inlet side of the off-air, which has not been used in the past, without requiring new power. It can be recovered.

Therefore, by supplying the recovered oxygen-enriched gas to the suction port of the air compressor via the additional passage, the oxygen concentration in the pressurized air can be increased compared to the conventional method and supplied to the air chamber of the fuel cell! The OII elemental diffusion rate in the gas electrode has been improved, compared to the conventional I! ! The electrochemical reaction, which was rate-limited by the diffusion rate of the element, is activated, which has the effect of increasing the power generation efficiency of the fuel cell, and by further increasing the reactant gas pressure, air! Conventional methods that increase the rate of diffusion of the arousal in the atmosphere have resulted in larger equipment and increased equipment costs, or problems with conventional methods that have lowered the oxygen consumption rate and increased the diffusion rate have resulted in the use of gas compressors. Increase in size and supplement 4! ! Problems such as increased loss are eliminated, and a pressurized fuel cell power generation system with high power generation efficiency can be provided while maintaining low equipment costs and operating costs.

In addition, if the separated and recovered oxygen-enriched gas is configured to be supplied to the fuel reformer burner side via an additional passage, the oxygen concentration in the combustion-supporting air can be increased to improve the combustion efficiency of the burner and stabilize it. In addition, it is possible to downsize the combustion-supporting air blower and reduce the loss of its auxiliary equipment. Furthermore, it is also possible to configure a combination of both, and in this case, the above effects of power generation efficiency and combustion efficiency, as well as effective use of energy as a whole system, are possible.
The effect of reducing operating costs and equipment costs can also be obtained.

[Brief explanation of the drawing]

Fig. 1 is a simplified system configuration diagram showing a pressurized fuel cell generation system according to an embodiment of the present invention, Fig. 2 is a system configuration diagram showing a different embodiment of the invention, and Fig. 3 is a conventional system configuration diagram. FIG. 2 is a system configuration diagram showing the system configuration. 1... Fuel cell, 2... Pneumatic a machine, 3... Fuel reformer, 4... Reforming raw material, 4A... Reformed gas, 4B
...off gas, 5...air, 5A, 30...pressurized air, 5B...off air, 6A, 6F...pressure reducer,
8... Combustion supporting air blower, 11... Matrix, 1
2.13... Electrode, 14.15... Reaction gas chamber, 1
6... Heat exchange tube, 17... Reforming reaction tube, 18... Reformer burner, 21... Separation device, 21A... Oxygen permeable membrane, 21B... Off air chamber, 21C... ...Oxygen-enriched gas chamber, 22...Radiator, 23...Condenser, 24.
35... Oxygen shinai +1 passage.

Claims (1)

[Claims] 1) A fuel cell comprising a fuel electrode and an air electrode that sandwich a matrix, a fuel gas chamber and an air chamber that supply a reactive gas to both electrodes, and a hydrogen-rich reformed gas in the fuel gas chamber. and an air compressor that supplies pressurized air to the air chamber; 1. A pressurized fuel cell power generation system, which is used as a heat source for a fuel reaction, and is equipped with an oxygen-permeable membrane type separation device for separating oxygen-enriched gas from the off-air on the outlet side of the air chamber. 2) The pressurized fuel cell power generation system according to claim 1, further comprising: a reaction air oxygenation passage for supplying the separated oxygen-enriched gas to the air suction side of the air compressor. 3) The pressurized fuel cell power generation system according to claim 1, further comprising an oxygen addition passageway for supplying oxygen-enriched gas to the combustion support air blower suction port side of the burner of the fuel reformer.