CN100517845C - A device that can make full use of hydrogen and oxygen in fuel cells - Google Patents

Abstract

This invention relates to a device for fully utilizing H2 and O2 of fuel cells including a H2 or O2 main pipeline, a H2 or O2 inlet pressure adjusting valve and a fuel cell stack, in which, the main pipeline is connected with the inlet and is set with a branch pipeline on the same direction, the other end of which is connected with the outlet of them, the inlet pressure adjusting valve adjusts the pressure of the H2 or O2 entering into the fuel cell stack to ensure that the H2 or O2 measurement ratio providing the stack is greater than 1.0 and the rest coming out from the outlet of the stack enters into the main pipeline by being absorbed by the branch one to be used in circulation.

Description

A device that can make full use of hydrogen and oxygen in fuel cells

technical field

The invention relates to a fuel cell, in particular to a device capable of making full use of hydrogen and oxygen in the fuel cell.

Background technique

An electrochemical fuel cell is a device that converts hydrogen and oxidants into electrical energy and reaction products. The internal core component of the device is the membrane electrode (Membrane Electrode Assembly, referred to as MEA). The membrane electrode (MEA) is composed of a proton exchange membrane and two porous conductive materials, such as carbon paper, sandwiched between the two sides of the membrane. On the two boundary surfaces of the membrane and the carbon paper, there are even and finely dispersed catalysts for initiating electrochemical reactions, such as metal platinum catalysts. Conductive objects can be used on both sides of the membrane electrode to draw the electrons generated during the electrochemical reaction through an external circuit to form a current loop.

At the anode end of the membrane electrode, the fuel can permeate through the porous diffusion material (carbon paper), and an electrochemical reaction occurs on the surface of the catalyst, losing electrons and forming positive ions, which can migrate through the proton exchange membrane, Reach the cathode end of the other end of the membrane electrode. At the cathode end of the membrane electrode, a gas containing an oxidant (such as oxygen), such as air, penetrates through the porous diffusion material (carbon paper), and electrochemically reacts on the surface of the catalyst to obtain electrons to form negative ions. Anions formed at the cathode end react with positive ions migrating from the anode end to form reaction products.

In a proton exchange membrane fuel cell that uses hydrogen as fuel and air containing oxygen as the oxidant (or pure oxygen as the oxidant), the catalytic electrochemical reaction of fuel hydrogen in the anode region produces positive hydride ions (or protons). The proton exchange membrane facilitates the migration of positive hydride ions from the anode region to the cathode region. In addition, the proton exchange membrane separates the hydrogen-containing fuel gas stream from the oxygen-containing gas stream so that they do not mix with each other and cause an explosive reaction.

In the cathode area, oxygen gets electrons on the surface of the catalyst to form negative ions, and reacts with positive hydrogen ions migrated from the anode area to generate water as a reaction product. In a proton exchange membrane fuel cell using hydrogen and air (oxygen), the anode reaction and cathode reaction can be expressed by the following equation:

Anode reaction: H ₂ → 2H ⁺ +2e

Cathode reaction: 1/2O ₂ +2H ⁺ +2e→H ₂ O

In a typical proton exchange membrane fuel cell, the membrane electrode (MEA) is generally placed between two conductive plates, and the surface of each guide plate in contact with the membrane electrode is formed by die-casting, stamping or mechanical milling to form at least More than one diversion groove. These current-guiding pole plates can be pole plates made of metal materials, or pole plates made of graphite materials. The fluid channels and flow guide grooves on these guide plates guide the fuel and oxidant into the anode area and the cathode area on both sides of the membrane electrode respectively. In the structure of a single proton exchange membrane fuel cell, there is only one membrane electrode, and the two sides of the membrane electrode are the deflectors of the anode fuel and the cathode oxidant respectively. These deflectors are not only used as current collectors, but also as mechanical supports on both sides of the membrane electrodes. The guide grooves on the deflectors are also used as passages for fuel and oxidant to enter the anode and cathode surfaces, and as a way to take away fuel cells during the operation of the fuel cell. Channels for the resulting water.

In order to increase the total power of the entire proton exchange membrane fuel cell, two or more single cells can usually be stacked in series to form a battery pack or connected in a tiled manner to form a battery pack. In direct-stacked and series-connected battery packs, there can be diversion grooves on both sides of a pole plate, one of which can be used as the anode diversion surface of one membrane electrode, and the other side can be used as the cathode of another adjacent membrane electrode. The diversion surface, this kind of plate is called a bipolar plate. A series of cells are connected together in a certain way to form a battery pack. The battery pack is usually fastened together by the front end plate, the rear end plate and the tie rods to form a whole.

A typical battery pack usually includes: (1) diversion inlet and diversion channel of fuel and oxidant gas, fuel (such as hydrogen, methanol or methanol, natural gas, hydrogen-rich gas obtained by reforming gasoline) and oxidant (mainly Oxygen or air) is evenly distributed into the diversion grooves of each anode and cathode surface; (2) the inlet and outlet of the cooling fluid (such as water) and the diversion channel, the cooling fluid is evenly distributed into the cooling channels in each battery pack, Absorb the heat generated by the electrochemical exothermic reaction of hydrogen and oxygen in the fuel cell and take it out of the battery pack for heat dissipation; (3) the outlet of the fuel and oxidant gas and the corresponding guide channel, when the fuel gas and oxidant gas are discharged, can Carry out the liquid and vapor state water generated in the fuel cell. Usually, the inlets and outlets of all fuels, oxidants, and cooling fluids are opened on one or both end plates of the fuel cell stack.

Proton exchange membrane fuel cells can be used not only as power systems for vehicles, ships, etc., but also as mobile or stationary power stations.

In order to improve the energy conversion efficiency of the entire fuel cell power generation system, the following requirements are required for the supply and utilization of fuel and oxidant:

(1) Fuel and oxidant supply the pressure on both sides of the fuel cell electrode to be basically balanced.

(2) Fuel supply The metering ratio of the fuel cell is generally greater than 1.0.

(3) The metering ratio of the oxidant supplied to the fuel cell is generally greater than 1.0.

(4) When the fuel (especially pure hydrogen) and oxidant (especially pure oxygen) are supplied to the fuel cell, the excess part with a stoichiometric ratio greater than 1.0 cannot be released from the fuel cell for nothing, but should be recycled and fully utilized.

Proton exchange membrane fuel cell is one of all fuel cells, generally using pure hydrogen as fuel and pure oxygen (or air) as oxidant. In order to improve the fuel and oxidant energy conversion efficiency of the entire proton exchange membrane fuel cell power generation system, the above four requirements must also be met, especially the fourth point, which is of great significance for making full use of fuel and oxidant.

In order to achieve this requirement of fully utilizing fuel and oxidant, there is a patented technology at present, the method introduced on US Patent 5,441,821, as shown in Figure 1, this technology has adopted a kind of device called ejector pump. The device utilizes the high-pressure inlet end (126 in the figure) to pass through the narrow and long flow channel and the small channel hole (202 in the figure) at high speed, sprays to the low-pressure air outlet end, and creates a vacuum state at the suction end (128 in the figure). The remaining fuel or oxidant in the fuel cell that is greater than the metering ratio of 1.0 is injected back to achieve the purpose of recycling and full utilization.

Although this ejector pump technology and ejector pump working method can achieve the purpose of making full use of fuel or oxidant, it has the following insurmountable shortcomings:

(1) The processing requirements of ejector pumps are very high and difficult. For different flow requirements, different inlet and outlet pressure requirements and different injection pump volume requirements; the processing differences of ejector pumps are very large and cannot achieve versatility .

(2) The inlet end of the ejector pump often requires a very high pressure of fuel or oxidant. After passing through the ejector pump, the pressure at the outlet end suddenly drops, resulting in a large pressure difference between the inlet end and the outlet end of the ejector pump. However, the supply pressure of fuel or oxidant in the fuel cell must generally be kept relatively constant, so a pressure regulation control device with very high control requirements must be added before the inlet end of the jet pump. When the fuel cell consumes fuel and the amount of oxidant changes , Front pressure can be adjusted automatically. When this pressure regulating control device fails, the pressure at the inlet end of the ejector pump will be equal to the pressure at the outlet end, causing the fuel cell to withstand ultra-high pressure and cause damage.

(3) This automatic pressure regulating device is mainly composed of a pressure sensor, a solenoid valve, and an electric regulating valve. It is a very expensive device, and it is easy to cause loss of control.

Contents of the invention

The object of the present invention is to provide a device with simple structure, convenient operation and low cost, which can make full use of hydrogen and oxygen in the fuel cell, in order to overcome the above-mentioned defects in the prior art.

The purpose of the present invention can be achieved through the following technical solutions: a device that can make full use of hydrogen and oxygen in a fuel cell, characterized in that it includes a hydrogen or oxygen intake main pipeline, a hydrogen or oxygen intake pressure regulating valve, a fuel The battery stack, the hydrogen or oxygen intake main pipeline is connected with the hydrogen or oxygen inlet of the fuel cell stack, the hydrogen or oxygen intake main pipeline is provided with a manifold in the same flow direction, and the other end of the manifold is connected to the fuel cell stack. The hydrogen or oxygen outlet of the cell stack is connected; the hydrogen or oxygen inlet pressure regulating valve regulates the hydrogen or oxygen pressure entering the fuel cell stack, and the hydrogen or oxygen pressure should ensure that the hydrogen or oxygen metering ratio supplied to the fuel cell stack is greater than 1.0 , the excess hydrogen or oxygen from the hydrogen or oxygen outlet of the fuel cell stack is sucked back to the hydrogen or oxygen intake main pipeline through the manifold for recycling.

The hydrogen or oxygen intake main pipeline is divided into one or more than one main pipeline, and each of the one or more hydrogen or oxygen intake main pipelines is provided with a manifold in the same flow direction.

The inlets of the one or more hydrogen or oxygen inlet main pipelines are connected as a whole, and the outlets of the one or more hydrogen or oxygen inlet main pipelines are merged and connected to the hydrogen or oxygen inlet of the fuel cell stack. More than one manifold merges and connects with the hydrogen or oxygen outlet of the fuel cell stack.

The connection between the hydrogen or oxygen intake main pipeline and the manifold is in the shape of a narrow throat.

The flow direction of the hydrogen or oxygen intake main pipeline and the manifold is arranged at an acute angle.

Compared with the prior art, the present invention has the following advantages:

(1) The pressure of the fuel or oxidant inside the fuel cell is easy to control, and only a mechanical pressure stabilizing or pressure regulating valve is required, and the price is cheap.

(2) This new invention device and method are relatively convenient to implement.

(3) Fuel cell fuel or oxidant can be fully utilized.

(4) The main channel at the manifold is processed into a narrow throat shape to increase the fluid flow rate and enhance the fluid attraction to the manifold.

Description of drawings

Fig. 1 is the structural representation of prior art;

Fig. 2 is the structural representation of embodiment 1 of the present invention;

Fig. 3 is the structural representation of embodiment 2 of the present invention;

Fig. 4 is the structural representation of the narrow throat in the fuel cell stack hydrogen or oxygen intake pipe of the present invention;

Fig. 5 is a schematic structural view of another narrow throat in the fuel cell stack hydrogen or oxygen intake pipe of the present invention.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing.

As shown in FIG. 4 , when the fluid I quickly passes through the main pipe 5 and the narrow throat 16 , the fluid II in the manifold 6 will be sucked into the main pipe 5 . The purpose of the narrow throat 16 is to increase the flow velocity of the fluid to the manifold to enhance the suction force. Connect the main pipe 5 with the fuel or oxidant inlet of the fuel cell, and connect the manifold 6 with the fuel or oxidant outlet in the fuel cell. And the pressure supplied by the fuel or oxidant of the main pipe fittings to the fuel cell is adjusted and balanced through the pressure regulating valve, so that the operating pressure of the fuel or oxidant inside the fuel cell is relatively constant, and the part of the fuel or oxidant with a metering ratio greater than 1.0 is passed through the manifold. Tube loop draws back.

In order to strengthen the fluid in the main pipeline to attract the fluid in the manifold, the following measures can be used to achieve the goal:

As shown in Figure 5, the main pipeline is divided into two branches, the diameter of the main pipeline is reduced, and the fluid in the main pipeline is divided into III and IV, so that the flow velocity of the fluid in the divided main pipeline 5, 5' is accelerated to achieve enhanced divergence Fluid suction purpose inside the tubes 6, 6'.

Connect the inlets of the main pipes 5 and 5' as a whole, connect the main pipes 5 and 5' to the fuel or oxidant inlet of the fuel cell, and connect the manifolds 6 and 6' to the fuel or oxidant outlet of the fuel cell If they are connected together, the excess fuel or oxidant in the fuel cell with a metering ratio greater than 1.0 can be sucked back to the main pipeline through the manifold. Of course, the main pipeline can also be divided into several branches (such as 3 branches, 10 branches, etc.), several branch pipelines are respectively connected to each branch main pipeline, and several branch main pipelines are merged into the fuel cell inlet, and several branch pipelines are connected to the fuel cell inlet. After being merged, it is connected to the outlet of the fuel cell, so as to increase the operating metering ratio of the fuel or oxidant in the fuel cell, and make 100% fully utilized.

Example 1

As shown in Figure 2, it is a hydrogen-air type 10-kilowatt fuel cell power generation system. Hydrogen gas at 2 to 1000 atmospheres can be stored in the hydrogen compression container 1, and the pressure can be stabilized at 0.1 to 5 atmospheres after passing through the pressure regulating and stabilizing valve 3. under some pressure. The air compression pump 2 can supply air pressure with a certain specific working pressure of 0.1 to 8 atmospheres. After the pressure regulating and stabilizing valve 4, the pressure stabilized is approximately equal to the pressure after the decompression and pressure stabilization of the above-mentioned hydrogen gas.

The hydrogen gas passes through the main supply channel pipe 5, and the flow velocity is increased at the narrow throat 16, and a vacuum suction is generated on the manifold 6. Hydrogen enters the fuel cell from the fuel cell inlet 7, and the part with a stoichiometric ratio of 1.0 participates in the electrochemical reaction to generate water, and the excess part with a stoichiometric ratio of 1.0 comes out from the fuel cell outlet 8 and enters the water vapor separator 9, where the water is separated and then enters Manifold 6, and recirculates the suction into the main flow line.

After the air is stabilized, it enters from the fuel cell inlet 14 and is directly discharged from the fuel cell outlet 10, so there is no need for full utilization of the cycle.

In addition, the fuel cell 20 also needs the cold air fluid to circulate through the fluid pump 13 and dissipate heat through the radiator 21 to achieve the purpose of cooling.

When the fuel cell 20 consumes hydrogen at a certain speed and has a stable output voltage and current, the hydrogen can be fully utilized.

Example 2

As shown in Fig. 3, it is a kind of hydrogen-oxygen type 10 kilowatt fuel cell power generation system, hydrogen compression container 1, oxygen compression container 2' each can store hydrogen and oxygen of 2 to 1000 atmospheric pressure. After the hydrogen and oxygen supply regulator valves 3 and 4 regulate and stabilize the pressure, the hydrogen and oxygen supply fuel cell pressure is stabilized at a certain pressure of 0.1 to 5 atmospheres, and the two pressures are roughly equal. Hydrogen and oxygen each pass through the supply main channel pipes 5, 11 and respectively increase their flow velocities at the narrow throats 16, 15, and respectively generate vacuum suction to the manifolds 6, 17. Hydrogen and oxygen enter the fuel cell through the inlets 7 and 14 of the fuel cell. Part of the hydrogen and oxygen with a stoichiometric ratio of 1.0 participate in the electrochemical reaction to generate water, and the fuel cell 20 outputs current and voltage to the outside. The excess hydrogen and oxygen that are greater than the metering ratio of 1.0 come out from the outlets 8 and 10 of the fuel cell and enter the water vapor separators 9 and 12 respectively. middle.

In addition, the fuel cell 20 also needs the cooling fluid to circulate through the fluid pump 13 and dissipate heat through the radiator 21 to achieve the purpose of cooling.

When the fuel cell 20 consumes hydrogen and oxygen at a certain speed and stabilizes the output voltage and current, the hydrogen and oxygen can be fully utilized.

Claims (4)

1. one kind can make the hydrogen of fuel cell and the device that oxygen makes full use of, it is characterized in that, comprise hydrogen or oxygen air inlet trunk line, hydrogen or oxygen inlet pressure adjusting valve and fuel cell pack, described hydrogen air inlet trunk line links to each other with the hydrogen inlet of fuel cell pack, the same flow direction of described hydrogen air inlet trunk line is provided with manifold, and the other end of this manifold links to each other with the hydrogen outlet of fuel cell pack; Described hydrogen inlet pressure adjusting valve is regulated the Hydrogen Vapor Pressure that enters fuel cell pack, this Hydrogen Vapor Pressure should be guaranteed the hydrogen metering ratio of fueling battery pile greater than 1.0, and the unnecessary hydrogen that comes out from the fuel cell pack hydrogen outlet attracts back hydrogen air inlet trunk line to recycle by manifold; Described oxygen air inlet trunk line links to each other with the oxygen inlet of fuel cell pack, and the same flow direction of described oxygen air inlet trunk line is provided with manifold, and the other end of this manifold links to each other with the oxygen outlet of fuel cell pack; Described oxygen inlet pressure adjusting valve is regulated the oxygen pressure that enters fuel cell pack, this oxygen pressure should be guaranteed the oxygen stoichiometry ratio of fueling battery pile greater than 1.0, and the unnecessary oxygen that comes out from the fuel cell pack oxygen outlet attracts back oxygen air inlet trunk line to recycle by manifold; The junction of described hydrogen or oxygen air inlet trunk line and manifold is narrow venturi shape.

2. a kind of hydrogen of fuel cell and device that oxygen makes full use of of making according to claim 1, it is characterized in that, described hydrogen or oxygen air inlet trunk line are divided into more than one, and the same flow direction of this above hydrogen or oxygen air inlet trunk line respectively is provided with manifold.

3. a kind of hydrogen of fuel cell and device that oxygen makes full use of of making according to claim 2, it is characterized in that, the import of a described above hydrogen air inlet trunk line is connected as a single entity, the back, outlet interflow of a described above hydrogen air inlet trunk line links to each other with the hydrogen inlet of fuel cell pack, and back, a described above manifold interflow links to each other with the hydrogen outlet of fuel cell pack; The import of a described above oxygen air inlet trunk line is connected as a single entity, the back, outlet interflow of a described above oxygen air inlet trunk line links to each other with the oxygen inlet of fuel cell pack, and back, a described above manifold interflow links to each other with the oxygen outlet of fuel cell pack.

4. a kind of hydrogen of fuel cell and device that oxygen makes full use of of making according to claim 1 is characterized in that the same flow direction of described hydrogen or oxygen air inlet trunk line and manifold is the acute angle setting.

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