CN1815785A

CN1815785A - Fuel cell with function of preventing back-fire

Info

Publication number: CN1815785A
Application number: CNA2005100237253A
Authority: CN
Inventors: 夏建伟; 胡里清
Original assignee: Shanghai Shen Li High Tech Co Ltd
Current assignee: State Grid Shanghai Electric Power Co Ltd; Shanghai Shenli Technology Co Ltd
Priority date: 2005-02-01
Filing date: 2005-02-01
Publication date: 2006-08-09
Anticipated expiration: 2025-02-01
Also published as: CN100392903C

Abstract

The fuel battery includes fuel cell pile, hydrogen storage, device for humidifying hydrogen, air filtering device, unit for humidifying air, coolant circulating pump, hydrogen circulating pump, radiator, and water-vapor separator for humidified hydrogen etc. the said separator includes body case. At least one piece of porous metal tube and a baffle plate are setup inside the body case. One end of the separator for humidified hydrogen is connected to the inlet of the device for humidifying hydrogen; and the other end is connected to hydrogen inlet end of fuel cell pile. Comparing with prior art, besides separating water and vapor from humidified hydrogen, the separator also provides function for preventing backfire from pipe of hydrogen.

Description

Fuel cell with anti-backfire function

Technical Field

The invention relates to a fuel cell, in particular to a fuel cell with an anti-backfire function.

Background

An electrochemical fuel cell is a device capable of converting hydrogen and an oxidant into electrical energy and reaction products. The inner core component of the device is a Membrane Electrode (MEA), which is composed of a proton exchange Membrane and two porous conductive materials sandwiched between two surfaces of the Membrane, such as carbon paper. The membrane contains a uniform and finely dispersed catalyst, such as a platinum metal catalyst, for initiating an electrochemical reaction at the interface between the membrane and the carbon paper. The electrons generated in the electrochemical reaction process can be led out by conductive objects at two sides of the membrane electrode through an external circuit to form a current loop.

At the anode end of the membrane electrode, fuel can permeate through a porous diffusion material (carbon paper) and undergo electrochemical reaction on the surface of a catalyst to lose electrons to form positive ions, and the positive ions can pass through a proton exchange membrane through migration to reach the cathode end at the other end of the membrane electrode. At the cathode end of the membrane electrode, a gas containing an oxidant (e.g., oxygen), such as air, forms negative ions by permeating through a porous diffusion material (carbon paper) and electrochemically reacting on the surface of the catalyst to give electrons. The anions formed at the cathode end react with the positive ions transferred from the anode end to form reaction products.

In a pem fuel cell using hydrogen as the fuel and oxygen-containing air as the oxidant (or pure oxygen as the oxidant), the catalytic electrochemical reaction of the fuel hydrogen in the anode region produces hydrogen cations (or protons). The proton exchange membrane assists the migration of positive hydrogen 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 to cause explosive reactions.

In the cathode region, oxygen gains electrons on the catalyst surface, forming negative ions, which react with the hydrogen positive ions transported from the anode region to produce water as a reaction product. In a proton exchange membrane fuel cell using hydrogen, air (oxygen), the anode reaction and the cathode reaction can be expressed by the following equations:

and (3) anode reaction:

and (3) cathode reaction:

in a typical pem fuel cell, a Membrane Electrode (MEA) is generally placed between two conductive plates, and the surface of each guide plate in contact with the MEA is die-cast, stamped, or mechanically milled to form at least one or more channels. The flow guide polar plates can be polar plates made of metal materials or polar plates made of graphite materials. The fluid pore channels and the diversion trenches on the diversion polar plates respectively guide the fuel and the oxidant into the anode area and the cathode area on two sides of the membrane electrode. In the structure of a single proton exchange membrane fuel cell, only one membrane electrode is present, and a guide plate of anode fuel and a guide plate of cathode oxidant are respectively arranged on two sides of the membrane electrode. The guide plates are used as current collector plates and mechanical supports at two sides of the membrane electrode, and the guide grooves on the guide plates are also used as channels for fuel and oxidant to enter the surfaces of the anode and the cathode and as channels for taking away water generated in the operation process of the fuel cell.

In order to increase the total power of the whole proton exchange membrane fuel cell, two or more single cells can be connected in series to form a battery pack in a straight-stacked manner or connected in a flat-laid manner to form a battery pack. In the direct-stacking and serial-type battery pack, two surfaces of one polar plate can be provided with flow guide grooves, wherein one surface can be used as an anode flow guide surface of one membrane electrode, and the other surface can be used as a cathode flow guide surface of another adjacent membrane electrode, and the polar plate is called a bipolar plate. A series of cells are connected together in a manner to form a battery pack. The battery pack is generally fastened together into one body by a front end plate, a rear end plate and a tie rod.

A typical battery pack generally includes: (1) the fuel (such as hydrogen, methanol or hydrogen-rich gas obtained by reforming methanol, natural gas and gasoline) and the oxidant (mainly oxygen or air) are uniformly distributed in the diversion trenches of the anode surface and the cathode surface; (2) the inlet and outlet of cooling fluid (such as water) and the flow guide channel uniformly distribute the cooling fluid into the cooling channels in each battery pack, and the heat generated by the electrochemical exothermic reaction of hydrogen and oxygen in the fuel cell is absorbed and taken out of the battery pack for heat dissipation; (3) the outlets of the fuel gas and the oxidant gas and the corresponding flow guide channels can carry out liquid and vapor water generated in the fuel cell when the fuel gas and the oxidant gas are discharged. Typically, all fuel, oxidant, and cooling fluid inlets and outlets are provided in one or both end plates of the fuel cell stack.

The proton exchange membranefuel cell can be used as a power system of vehicles, ships and other vehicles, and can also be used as a movable and fixed power generation device.

When the proton exchange membrane fuel cell can be used as a vehicle power system, a ship power system or a mobile and fixed power station, the proton exchange membrane fuel cell must comprise a cell stack, a fuel hydrogen supply system, an air supply subsystem, a cooling and heat dissipation subsystem, an automatic control part and an electric energy output part.

Fig. 1 is a fuel cell power generation system, in fig. 1, 1 is a fuel cell stack, 2 is a hydrogen storage bottle or other hydrogen storage device, 3 is a pressure reducing valve, 4 is an air filtering device, and 5 is an air compression supply device; 6. the hydrogen and air separator 6' is the hydrogen and air separator, the water tank 7, the cooling fluid circulating pump 8, the radiator 9, the hydrogen circulating pump 10, and the hydrogen and air humidifier 11, 12.

The operation of the fuel cell requires the humidification of the hydrogen side to ensure the normal operation of the fuel cell. Because of the distance between the hydrogen-side humidifier of the fuel cell and the hydrogen-side inlet of the fuel cell, water drops are separated out of the gas flow, and the collision of the water drops can generate larger water drops, even a water mass is suspended in the gas flow. Such large water droplets or water masses suspended in the air stream, which once entered the fuel cell stack, have a fatal effect on the performance of the electrodes in the stack, as shown in fig. 2, must be removed. Hydrogen, on the other hand, is a high energy fuel, but also a very highly flammable gas. The problem of backfire prevention must be considered because the backfire may occur when the hydrogen gas in the pipeline is mixed with air and exposed to an open fire, which may cause fuel explosion in theentire hydrogen storage cylinder.

Disclosure of Invention

The present invention has been made to overcome the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a fuel cell having an anti-backfire function, which can make humidified hydrogen gas entering a fuel cell stack to participate in a reaction free from liquid substances, thereby improving the operation stability thereof.

The purpose of the invention can be realized by the following technical scheme: a fuel cell with anti-backfire function comprises a fuel cell stack, a hydrogen storage device, a hydrogen pressure reducing valve, a hydrogen humidifying device, a stack-outlet hydrogen gas-water-vapor separator, a hydrogen circulating pump, an air filtering device, an air compression supply device, an air humidifying device, a stack-outlet air gas-water-vapor separator, a water tank, a cooling fluid circulating pump and a radiator.

The number of the porous metal tubes is three.

The porous metal pipe is a porous stainless steel pipe.

The humidifying hydrogen gas water-vapor separator is vertically arranged, the partition plate is arranged on the middle upper part of the inner cavity of the separator shell, the partition plate divides the inner cavity of the shell into an upper cavity and a lower cavity, at least one hole corresponding to the porous metal tube is formed in the partition plate, the porous metal tube is in butt joint with the partition plate hole in the lower cavity, one end of the porous metal tube is an opening, the other end of the porous metal tube is of a closed structure, the lower side part of the lower cavity is provided with a humidifying hydrogen gas inlet, the bottom of the lower cavity is providedwith a water outlet, and the top of the upper cavity is provided with a wet hydrogen gas outlet.

The water outlet extends upwards to form an inverted horn shape, and the water outlet is provided with a normally closed electromagnetic valve for controlling timed discharge.

The shell is cylindrical.

The shell and the partition board are made of stainless steel materials, and the temperature for melting and blocking the propagation of hydrogen flame is not higher than 250 ℃.

As shown in FIG. 3, the present invention uses a special material-porous stainless steel tube. The material can separate water from hydrogen, when the gas flow enters the humidifying hydrogen water-vapor separator, the hydrogen can diffuse into the humidifying hydrogen water-vapor separator through the porous stainless steel pipe and come out from the wet hydrogen outlet at the other end of the separator, and the water molecules are blocked by the special material and discharged through the water outlet at the bottom, thus achieving the purpose of water-vapor separation. And the water-vapor separator also has the function of preventing backfire, once the mixed air in the hydrogen pipeline in the fuel cell stack is ignited by open fire, the fire can rapidly spread along the hydrogen in the pipeline, when the water-vapor separator is reached, the porous stainless steel pipe can be sintered and blocked immediately when meeting hydrogen flame, and the flame is blocked, so that the function of preventing the backfire into the gas storage tank storing a large amount of hydrogen can be achieved. The present invention is called a fuel cell having an anti-backfire function.

Drawings

FIG. 1 is a schematic diagram of a conventional fuel cell;

FIG. 2 is a schematic diagram of the formation of water droplets and suspended water clusters in the conduit between the outlet of the hydrogen humidifier and the hydrogen inlet of the fuel cell stack in a prior art fuel cell;

FIG. 3 is a schematic structural diagram of a humidified hydrogen gas-water-vapor separator of a fuel cell according to the present invention.

Detailed Description

The invention will be further explained with reference to the drawings.

Examples

As shown in fig. 3, a fuel cell with anti-backfire function comprises a fuel cell stack 1, a hydrogen storage device 2, a hydrogen pressure reducing valve 3, an air filtering device 4, an air compression supply device 5, a stack-outlet hydrogen-gas-vapor separator 6, a stack-outlet air-gas-vapor separator 6', a water tank 7, a cooling fluid circulating pump 8, a radiator 9, a hydrogen circulating pump 10, a hydrogen humidifying device 11, an air humidifying device 12 and a humidifying hydrogen-gas water-vapor separator 13, wherein the humidifying hydrogen-gas water-vapor separator comprises a stainless steel shell 131, three (hydrogen) gas-permeable and water-impermeable porous stainless steel pipes 132 and a stainless steel partition plate 133 are arranged in the shell 131, and the shell 131 is cylindrical.

The humidifying hydrogen gas water-vapor separator 13 is vertically arranged, the clapboard 133 is arranged at the middle upper part of the inner cavity of the separator shell, the clapboard 133 divides the inner cavity of the shell into an upper cavity and a lower cavity, three holes 134 corresponding to the porous stainless steel tube 132 are arranged on the clapboard 133, the porous stainless steel tube 132is butted with the clapboard holes 134 at the lower cavity, the upper end of the porous stainless steel tube 132 is open, the lower end is closed, the lower side part of the lower cavity is provided with a humidifying hydrogen gas inlet 135, the bottom is provided with an inverted horn-shaped water outlet 136, and the top of the upper cavity is provided with a wet hydrogen gas outlet 137.

As shown in fig. 3 and with reference to fig. 1, the humidified hydrogen gas water-vapor separator 13 has one end communicating with the outlet end of the hydrogen humidifying device 11 and the other end communicating with the hydrogen inlet end of the fuel cell stack 1.

As shown in fig. 3 and fig. 1 and fig. 2, in this embodiment, after passing through a section of pipe 121, the humidified hydrogen gas from the outlet end of the hydrogen humidifying device 11 in a 50kw fuel cell engine inevitably condenses some small water droplets 122 or suspended water mass 123, and after entering the humidified hydrogen gas inlet 135 of the humidified hydrogen gas-steam separator 13 according to the present invention, the humidified hydrogen gas can diffuse into the humidified hydrogen gas through the porous stainless steel pipe 132 and exit from the humidified hydrogen gas outlet 137 at the other end of the partition plate 133, immediately enters the hydrogen gas inlet of the fuel cell stack 1 to react, and water molecules are blocked by this special material, and are discharged through the water outlet 136 at the bottom and a normally closed electromagnetic valve 138, which are controlled to be opened at regular time, so as to achieve the purpose of water-steam separation. In addition, the water-vapor separator 13 of this embodiment also has a function of preventing backfire, so that once the mixed air in the hydrogen pipeline of the fuel cell stack 1 is ignited by an open fire, the fire will quickly spread along the hydrogen in the pipeline, and when reaching the water-vapor separator 13, the water-vapor separator 13 can play a role of preventing backfire due to the sintering and flame-retardant effects of the porous stainless steel pipe 132.

In this embodiment, three porous stainless steel tubes 132 are used, and the inner diameter of the porous stainless steel tube 132 is 2cm and the length thereof is 10 cm; in this way, one, two or even more porous stainless steel tubes 132 may be used according to the flow rate of the humidified hydrogen to be treated, and other materials may be used for the housing 131 and the partition 133, so as to derive more embodiments, which should be construed as being within the scope of the present invention.

Claims

1. A fuel cell with anti-backfire function comprises a fuel cell stack, a hydrogen storage device, a hydrogen pressure reducing valve, a hydrogen humidifying device, a stack-outlet hydrogen gas-water-vapor separator, a hydrogen circulating pump, an air filtering device, an air compression supply device, an air humidifying device, a stack-outlet air gas-water-vapor separator, a water tank, a cooling fluid circulating pump and a radiator.

2. The fuel cell with the function of preventing the back fire according to claim 1, wherein the number of the porous metal tubes is three.

3. The fuel cell with the function of preventing the back fire according to claim 1 or 2, wherein the porous metal tube is a porous stainless steel tube.

4. The fuel cell of claim 1, wherein the humidified hydrogen gas water-vapor separator is vertically disposed, the separator is disposed at the middle upper portion of the inner cavity of the separator housing, the separator divides the inner cavity of the housing into an upper chamber and a lower chamber, the separator is provided with at least one hole corresponding to the porous metal tube, the porous metal tube is in butt joint with the separator hole at the lower chamber, the porous metal tube has an open end at one end and a closed end at the other end, the lower side portion of the lower chamber is provided with a humidified hydrogen gas inlet, the bottom portion of the lower chamber is provided with a water outlet, and the top portion of the upper chamber is provided with a wet hydrogen gas outlet.

5. The fuel cell with the function of preventing the back fire as claimed in claim 4, wherein the water outlet extends upwards to form an inverted horn shape, and the water outlet is provided with a normally closed solenoid valve for controlling the timed discharge.

6. The fuel cell with an anti-backfire function as claimed in claim 1, wherein said case is cylindrical.

7. The fuel cell of claim 1, wherein the housing and the separator are made of stainless steel and have a melting point of not higher than 250 ℃.