CN100388543C - A fuel cell with high operational stability - Google Patents

Abstract

The invention relates to a fuel cell with high operational stability, comprising a fuel cell stack, a hydrogen storage device, a hydrogen pressure reducing valve, a hydrogen pressure stabilizing valve, an air filter device, an air compression supply device, and a first hydrogen water-steam separation device, second hydrogen water-steam separator, first air water-steam separator, second air water-steam separator, water tank, cooling fluid circulation pump, radiator, hydrogen circulation pump, hydrogen humidifier, air humidifier Wet device, the second hydrogen water-steam separator is arranged at the hydrogen gas inlet end of the fuel cell stack, and the second air water-steam separator is arranged at the air inlet end of the fuel cell stack. Compared with the prior art, the present invention sets a high-efficiency water-steam separator at the feed gas inlet of the fuel cell stack, so that the hydrogen and air entering the fuel cell stack are not brought in by liquid water, thereby ensuring the fuel cell Running stability.

Description

A fuel cell with high operational stability

technical field

The present invention relates to a fuel cell, in particular to a fuel cell with high operating stability.

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 guide plates can be made of metal or graphite. 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, 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 outlet of the fuel and oxidant gas and the corresponding diversion 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 as the power system of vehicles, ships and other vehicles, and can also be used as mobile and fixed power generation devices.

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

Figure 1 is a typical fuel cell power generation system at present. In Figure 1, 1 is a fuel cell stack, 2 is a hydrogen storage bottle or other hydrogen storage device, 3 is a hydrogen pressure reducing valve, 4 is an air filter device, and 5 is an air compression supply device, 6 is a hydrogen water-steam separator, 6' is an air water-steam separator, 7 is a water tank, 8 is a cooling fluid circulation pump, 9 is a radiator, 10 is a hydrogen circulation pump, 11 and 12 are respectively hydrogen, Air humidifier.

According to the integration and operation principle of the current typical fuel cell power generation system, the hydrogen and air transported to the fuel cell stack must be stabilized and passed through the humidification devices 11 and 12 to become humid air and hydrogen at a certain relative humidity and temperature. Then the humid air and hydrogen enter the fuel cell stack for electrochemical reaction. Otherwise, when dry or insufficiently humidified air and hydrogen are transported to the fuel cell stack, excess air and hydrogen can cause dehydration of the proton exchange membrane in the membrane electrode, the core component of the fuel cell stack, and the dehydration of the proton exchange membrane will As a result, the internal resistance of the fuel cell increases sharply, and the operating performance drops sharply.

However, the hydrogen and air transported to the fuel cell stack by the current technical solution become moist air with a certain relative humidity and temperature after humidification, and the hydrogen directly enters the fuel cell stack for electrochemical reaction, which has the following technical defects:

(1) When the flow of hydrogen and air delivered to the fuel cell stack changes greatly, for example, when the flow rate is small, it is easy to cause overhumidification, and when the temperature drops, it is easy to condense a small amount of liquid water before entering the fuel cell stack. This kind of liquid water will be brought into the fuel cell hydrogen diversion groove and air diversion groove respectively by the wet hydrogen gas and the humid air, causing the water diversion groove to be blocked. Water blockage in the hydrogen diversion groove or air diversion groove in a single cell will cause the single cell to be in a state of starvation due to insufficient supply of fuel hydrogen or air, and the performance of the single cell will drop sharply, and in severe cases it will cause the electrode Reverse polarity and burn.

(2) When the pressure of hydrogen and air delivered to the fuel cell stack fluctuates, such as when the pressure increases, it is easy to cause the humidified air with high relative humidity when the original pressure is small, and the hydrogen gas will condense when it enters the fuel cell stack. A small amount of liquid water, the consequence that causes is also identical with above-mentioned (1) consequence.

The integration and operation principle of the current fuel cell power generation system In order to prevent the above-mentioned condensate water blocking problem, it is generally selected to place the humidifying devices 11 and 12 as close as possible to the fuel cell stack, and to wrap the pipelines for transporting air and hydrogen with heat-insulating layers to prevent Thermal condensation occurs. However, these measures still cannot completely prevent the occurrence of the above-mentioned problems, and the battery operation is still not stable enough.

Contents of the invention

The object of the present invention is to provide a fuel cell with high operational stability that can uniformly humidify raw material hydrogen and air 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 fuel cell with high operational stability, including a fuel cell stack, a hydrogen storage device, a hydrogen pressure reducing valve, a hydrogen pressure stabilizing valve, an air filter device, and an air compression supply device, the first hydrogen water-steam separator, the first air water-steam separator, water tank, cooling fluid circulation pump, radiator, hydrogen circulation pump, hydrogen humidification device, air humidification device, the first hydrogen The water-steam separator is arranged at the hydrogen outlet end of the fuel cell stack, and the first air water-steam separator is arranged at the air outlet end of the fuel cell stack, and it is characterized in that it also includes a second hydrogen water-steam separator , the second air water-steam separator, the second hydrogen water-steam separator is arranged at the hydrogen inlet end of the fuel cell stack, and the second air water-steam separator is arranged at the air inlet of the fuel cell stack end.

The second hydrogen water-steam separator is arranged between the hydrogen humidifying device and the hydrogen inlet port of the fuel cell stack.

The second hydrogen water-steam separator is located near the hydrogen inlet of the fuel cell stack.

The second air water-steam separator is arranged between the air humidifying device and the air inlet of the fuel cell stack.

The second air water-steam separator is located near the air inlet of the fuel cell stack.

The second hydrogen water-steam separator adopts a low flow resistance hydrogen water-steam separator.

The second air water-steam separator adopts a low flow resistance air water-steam separator.

Compared with the prior art, the present invention adopts a water-steam separator with high efficiency and small flow resistance, which is installed as close as possible to the feed gas inlet of the fuel cell stack, so that the humidified hydrogen and air first enter this The water-steam separator then immediately enters the fuel cell stack for chemical reactions. In this way, before the hydrogen and air enter the fuel cell stack after humidification, even if the temperature drops and the pressure fluctuation becomes larger, the condensed water can be completely separated in the water-steam separator to ensure that when entering the fuel cell stack No liquid water is brought in, so that the raw material hydrogen and air humidification are uniform and appropriate, and the fuel cell operates stably.

Description of drawings

FIG. 1 is a schematic structural diagram of an existing fuel cell operating system;

Fig. 2 is the structural representation of fuel cell of the present invention;

Fig. 3 is the structural representation of hydrogen water-steam separator of the present invention;

Fig. 4 is a schematic structural view of the air water-steam separator of the present invention.

Detailed ways

The present invention will be further described below in conjunction with specific examples.

Example

As shown in Figure 2 and in conjunction with Figure 1, a fuel cell with high operational stability includes a fuel cell stack 1, a hydrogen storage device 2, a hydrogen pressure reducing valve 3, a hydrogen pressure stabilizing valve 23, and an air filter device 4 , air compression supply device 5, first hydrogen water-steam separator 6, first air water-steam separator 6', water tank 7, cooling fluid circulation pump 8, radiator 9, hydrogen circulation pump 10, hydrogen humidification device 11. Air humidification device 12, second hydrogen water-steam separator 13, second air water-steam separator 14, the first hydrogen water-steam separator 6 is located at the hydrogen outlet end of the fuel cell stack 1 , the first air water-steam separator 6' is set at the air outlet end of the fuel cell stack 1, and the second hydrogen water-steam separator 13 is set at the hydrogen gas inlet end of the fuel cell stack 1, the The second air water-steam separator 14 is arranged at the air inlet end of the fuel cell stack 1 .

The above-mentioned second hydrogen water-steam separator 13 is further arranged between the hydrogen humidifying device 11 and the hydrogen inlet of the fuel cell stack 1, and the second hydrogen water-steam separator 13 is arranged near the hydrogen inlet of the fuel cell stack 1 place.

The above-mentioned second air water-steam separator 14 is further arranged between the air humidifier 12 and the air inlet of the fuel cell stack 1, and the second air water-steam separator 14 is arranged near the air inlet of the fuel cell stack 1 place.

The above-mentioned second hydrogen water-steam separator 13 adopts a high-efficiency, low-flow-resistance hydrogen water-steam separator. The above-mentioned second air water-steam separator 14 is an air water-steam separator with high efficiency and low flow resistance.

As shown in Figure 3 and Figure 4, the above-mentioned second hydrogen and air water-steam separators should be individually designed according to the power of the fuel cell stack and the flow rates of hydrogen and air. In this embodiment, a fuel cell with a power of 50KW is used. The second hydrogen water-steam separator 13 of this fuel cell comprises a hydrogen gas inlet pipe 131, a separator body 132, a drain pipe 133, a drain solenoid valve 134, and a hydrogen gas outlet pipe 135, and the separator body 132 is cylindrical, high 100mm, diameter 80mm, described drainage pipe 133 is located at the bottom of separator body 132, and described hydrogen gas inlet pipe 131, hydrogen outlet pipe 135 are arranged at the top of separator body 132; The hydrogen contains part of the condensed water. After being separated by the separator body 132, the condensed water in the humidified hydrogen is completely separated, and the hydrogen that goes out from the hydrogen outlet pipe 135 (immediately enters the fuel cell stack 1 to participate in the reaction) is free of liquid water. Humidified hydrogen, thus ensuring the operation stability of the fuel cell.

The second air water-steam separator 14 of this fuel cell comprises an air intake pipe 141, a separator body 142, a drain pipe 143, a drain solenoid valve 144, and an air outlet pipe 145, and the separator body 142 is cylindrical in shape, high 200mm, diameter 150mm, described drainage pipe 143 is located at the bottom of separator body 142, and described air inlet pipe 141, air outlet pipe 145 are arranged at the top of separator body 142; The humidification that enters from air inlet pipe 141 The air contains some condensed water. After being separated by the separator body 142, the condensed water in the humidified air is completely separated, and the air that goes out from the air outlet pipe 145 (immediately enters the fuel cell stack 1 to participate in the reaction) is free of liquid water Humidified air, thus ensuring the stability of the fuel cell operation.

The drain solenoid valves 134 and 144 are opened to drain water at regular intervals between 1 and 360 seconds.

Claims (5)

1. A fuel cell, comprising a fuel cell stack, a hydrogen storage device, a hydrogen pressure reducing valve, a hydrogen pressure stabilizing valve, an air filter, an air compression supply device, a first hydrogen water-steam separator, a first air water-steam Separator, water tank, cooling fluid circulation pump, radiator, hydrogen circulation pump, hydrogen humidification device, air humidification device, the first hydrogen water-steam separator is arranged at the hydrogen outlet end of the fuel cell stack, and the The first air water-steam separator is arranged at the air outlet end of the fuel cell stack, and is characterized in that it also includes a second hydrogen water-steam separator, a second air water-steam separator, and the second hydrogen water - The steam separator is arranged at the hydrogen inlet end of the fuel cell stack, and the second air water-steam separator is arranged at the air inlet end of the fuel cell stack. 2. A fuel cell according to claim 1, characterized in that the second hydrogen water-steam separator is arranged between the hydrogen humidifying device and the hydrogen inlet of the fuel cell stack. 3. The fuel cell according to claim 1, wherein the second air water-steam separator is arranged between the air humidifying device and the air inlet of the fuel cell stack. 4. A fuel cell according to claim 1, characterized in that the second hydrogen water-steam separator adopts a low flow resistance hydrogen water-steam separator. 5. A fuel cell according to claim 1, characterized in that, the second air water-steam separator adopts a low flow resistance air water-steam separator.

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