JPH01124962A - Alkaline electrolyte fuel cell system - Google Patents

Abstract

PURPOSE:To quickly preheat a fuel cell main body by burning purge H2 and purge O2 produced when N2 is replaced by reaction gas in a catalyst combustor, and by circulating the reaction gas containing heated N2 to each unit cell. CONSTITUTION:H2 or purge H2 supplied to a H2 circulation circuit 11 is used as a fuel gas, and O2 or purge O2 supplied to an O2 circulation circuit 21 is used as an oxidizing agent gas. A heating device including a catalyst combustor 44 is connected to the H2 circulation circuit 11 or the O2 circulation circuit 21 and an inert gas supply passage 31 through a valve. A fuel cell main body 1 is preheated to a specified temperature necessary for power generation. By utilizing the time required to replace N2 with reaction gas and reaction gas which is usually exhausted because of containing N2, the fuel cell main body whose temperature is 15 deg.C or lower is preheated to a temperature of several tens degrees centigrade necessary for power generation without specific preheating time and a specific energy source.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an alkaline electrolyte fuel cell device, 2. Particularly, an apparatus for generating electricity, and 9. Regarding.

[Conventional technology]

FIG. 3 is a piping system diagram showing the main parts of a conventional alkaline electrolyte fuel cell device. In the figure, a fuel cell main body 1 is configured as a stack of m layers of single cells each having an electrolyte chamber sandwiched between a fuel electrode and an oxidizer electrode, and each single cell has a hydrogen chamber and an oxidizer gas chamber as fuel gas chambers. It has an oxygen chamber. H in the hydrogen room! H with circulation 7 am 13 and condenser Ika 14 fc! A circulation circuit 11 is connected, and hydrogen gas H! H3 (hereinafter abbreviated as H2) supplied from a supply pipe 12 is forcedly circulated by a circulation fan 13, and a condenser 14 condenses and separates water produced by power generation. 11th and H snow cooling is carried out. There is also 0 in the oxygen chamber! Circulation 7 Anne 23
0! circulation circuit 21 is connected), oxygen gas is 0! (hereinafter abbreviated as 0!) is forcibly circulated through the 03 circulation 7 ann 23, and the heat generated by power generation is cooled by the fan 24 to a temperature suitable for power generation ( The temperature of the fuel cell main body 1 is maintained within a range (usually in the range of several tens of degrees Celsius to about 100 degrees Celsius).

In addition, 31 is nitrogen gas Ns (hereinafter N
2), one of which communicates with the H: circulation circuit 11 via a valve 32 and piping 33, and the other communicates with the H: circulation circuit 11 via a valve 34 and piping 35. It is connected to the circulation circuit 21, and when power generation is stopped, the H33 circulation path 11 and 0 are connected.
The reactive gases B and 02 in the two-circuit circuit 21 are replaced with N, preventing the reactive gases from coming into contact with each other within the fuel cell body, maintaining safety, and at the start of power generation, tHs and 0! A purge operation of N2 is performed. Valve 15 is the N2 purge valve on the N2 circulation circuit side, and valve 25 is 0! 0 on the circulation circuit side
．． It is a purge valve.

[Problem that the invention seeks to solve]

As shown in Figure 4, an example of the cell voltage-temperature characteristic diagram, an alkaline electrolyte fuel cell exhibits a characteristic in which the cell voltage decreases as the temperature of the fuel cell body decreases, especially when the cell temperature is 15°C. If the temperature drops below this level, the fuel cell becomes difficult to operate or even becomes inoperable. For fuel cells installed in winter or in cold regions, the cell temperature may drop to 15% when power generation is stopped.
As a countermeasure for this problem, conventional devices are equipped with an auxiliary heater 40 in the fuel cell main body 1, as shown in FIG. In order to prepare for the prompt start of power generation, K needs to be kept warm so that the fuel cell does not drop below a predetermined temperature, which increases power consumption and reduces the overall efficiency of the fuel cell device. There is a drawback that it decreases.

An object of the present invention is to quickly preheat the fuel cell main body to a temperature suitable for power generation without requiring any special preheating time or electric power when the fuel cell starts to generate power.

[Means for resolving issues]

In order to solve the above problems, according to the present invention, an inert gas is communicated via a stop valve with two circulation circuits that supply and circulate cooling fuel gas as a reaction gas and an oxidizer gas to the fuel cell main body. in which the inert gas is replaced by the reactant gas at the time of startup of the fuel cell, and one of the two circulation circuits communicates with the inert gas supply passage via a valve. The fuel cell body is equipped with a heating device for the reaction gas including a catalytic combustor, and the fuel cell itself generates electricity using the combustion heat of the mixed gas generated during gas replacement. Qi
The temperature shall be preheated to ii.

[Effect]

In the above means, the replacement operation from N to the reaction gas is performed at a comparatively slow speed at the start of operation of the fuel cell, and N
This was obtained by focusing on the fact that the reaction gas containing "s t" is discarded as purge H3゜purge O1, and by using N2 or purge H2 supplied to the N2 circulation circuit for the replacement operation as a fuel gas, 0! 0 supplied to the circulation circuit
m1t or purge 0! A heating device including a catalytic combustor that uses oxidizing gas as an oxidizing gas is installed to communicate with the 4-side or 02-side circulation circuit and the inert gas supply passage through a valve, and the generated heat is used to operate the fuel cell main body for power generation. By preheating to a possible predetermined temperature, the temperature can be reduced to 15°C or less by taking advantage of the time required to replace the reaction gas from ')% 2 kg! and the reaction gas being discarded because it contains N2. It is possible to preheat the fuel cell body, which is currently cold, to an operating temperature on the order of several tens of degrees Celsius capable of generating electricity, without requiring special preheating time or an energy source, and by using gas heated by a heating device. is supplied to each unit cell, so each unit cell can be preheated evenly and quickly compared to heat conduction from an auxiliary heater placed at the end of the cell stack.

〔Example〕

The present invention will be described below based on implementation examples.

FIG. 1 is a piping diagram showing a device according to an embodiment of the present invention, and the same parts as in the prior art are designated by the same reference numerals, and detailed explanation thereof will be omitted. In the figure, a catalytic combustor 41 as a heating device is arranged in a branch pipe section 43 having a stop valve 42 provided in parallel with the stop valve 11AK of the N2 circulation circuit 11, and the catalytic combustor 41 has a valve 44 and an inert gas 0 through the piping section 35 of the supply passage 31! 0 of the circulation circuit 22. It is formed so as to communicate with the supply piping 22 side.

In the apparatus configured as described above, when the fuel cell is in a stopped state, the circulation circuits 11 and 21KN2 are filled with a predetermined pressure, and the fuel cell is cooled down to 15° C. or less, power generation operation is to be started. In this case, first stop valve 11
A is closed, the valve 42 is opened, the H1 circulation circuit is switched to the branch pipe section 43 side, the circulation 7 parts 13 and 23 are driven, and the valves 32 and 34 of the inert gas supply passage 31 are closed.

Next, H, purge valve 15 and O! By using the purge valve 25, the contained N3 gas is gradually purged, and at the same time, N3 and Ol corresponding to the purging amount of N are supplied to each supply pipe 1.
By supplying from 2 and 22, the fuel cell main body 1
While maintaining the pressure balance between the hydrogen chamber and the oxygen groups, the replacement of the nitrogen gas with the reaction gas is started. Then, the length of the valve 44 is adjusted, and a part of the 0 yen supplied from the 0 snow supply pipe 22 is supplied to the catalytic combustor 41 using the pipe 35 of the inert gas supply passage. At this time, the catalytic combustor 41 has H
, and N is flowing, so that H is generated on the platinum catalyst held by the base material in the combustor.

and O snow contact and burn, and the generated heat heats the mixed gas circulating in the R1 circulation circuit 11, and the heated mixed gas circulates evenly through the hydrogen chambers of each single cell in the fuel cell main body 1. ) Each single cell can be heated almost equally by 710 degrees. Note that the catalytic combustor 41
The amount of gas supplied to the catalytic combustion #iI should be kept below 2y, the amount of gas flowing through the catalytic combustion #iI, and below the permissible explosive limit concentration of 03, while maintaining safety and maintaining the fuel cell. The main body can be preheated to an operating temperature of 20° C. or higher at which it can generate electricity. At the end of preheating, the valves 44 and 42t are closed and the valve 11At is opened to switch the H circulation circuit to a steady circuit, thereby enabling power generation operation.Also, after completing the replacement with the reaction gas, the purge valve 15 is closed. and 25 are closed or adjusted.

In this way, in the embodiment device, the fuel cell main body is preheated tN! N! generated when replacing with reaction gas! By using a catalytic combustor that generates heat using a mixed reaction gas, there is no need to supply external energy, and therefore a decrease in the power generation efficiency of the fuel cell can be prevented. Also,
Since the heated mixed gas circulates through each single cell and preheats the fuel cell evenly and efficiently, the time required for preheating is shortened, and the time required for replacing N2 with the reactant gas can be effectively utilized for preheating. Therefore, the power generation operation of the fuel cell device can be started promptly.

Figure 2 is a piping diagram showing a different embodiment of this invention;
A heating device 50 for reactant gas (Hz in the figure) is connected to the N2 par 2 square 15 side of the N2 circulation circuit 11 via a valve 53, and a catalytic combustor 51 uses purge H2 as a fuel gas. The μ heat exchanger 52 is connected to the circulation circuit 11 to heat the mixed gas of R8 and N2 circulating in the circulation circuit 11. The configuration is different from the above-mentioned implementation. The preheating operation in this device is H! The purge valve 15 is closed and the valve 53 is opened to purge the purge R3 through the catalytic combustor 51 and the heat exchanger 52t. The fuel is then supplied to the catalytic combustor 51 via the valve 44 for combustion. Purge gas 55 heated by combustion functions as a heating medium in heat exchanger 52, and N2 and N! flow through the H snow circulation circuit. Since the mixed gas is heated, the fuel cell main body 1 is preheated in the same manner as in the previous embodiment. At the end of preheating, valves 44 and 53 are closed, and valves 1 and 5 are re-opened.
By configuring the heating device 50 as described above, even if power generation operation is performed, the purge H2, which would normally be discarded, can be reused in a clear manner in the above-described embodiment. Overall efficiency can be further increased.

In addition, although the example shows the case where the heating device is installed on the H22 circulation path side, it is also possible to install the heating device on the 02 circulation circuit, and in this case, the flow rate ratio of H2 and 02 is changed. Reverse it.

〔Effect of the invention〕

As mentioned above, in order to start up a fuel cell body that has cooled down to a temperature below the temperature at which it can generate electricity, a heater mainly consisting of a catalytic combustor is provided in either the sH2 circulation circuit or the 02 circulation circuit, and N snow is turned into a reactant gas. Insect remover purge H to be replaced with
! , purge 02 is combusted in the catalytic combustor Ki, and the heated reactant gas containing N is circulated through each unit cell to preheat the fuel cell main body to a temperature capable of generating electricity. As a result, each single cell is directly heated by the circulating heated gas, which is much faster than conventional devices that preheat each cell by heat conduction from an auxiliary heater placed at the end of the fuel cell body made up of a cell stack. An alkaline electrolyte fuel that allows a single cell to be preheated quickly and uniformly, as well as making effective use of the time required to replace N snow with reactive gas, allowing a cold fuel cell to quickly start generating electricity. A battery device can be provided.

In addition, thermal energy can be obtained by effectively using purge R2 or purge 0, which is normally discarded, and the preheating time is shortened so that the temperature of the fuel cell itself does not drop below the temperature at which it can generate electricity. Since there is no need for constant heat retention, it is possible to provide an alkaline electrolyte fuel cell device with high energy saving effects and high overall efficiency.

[Brief explanation of the drawing]

Fig. 1 is a piping diagram showing a device according to an embodiment of the present invention, Fig. 2 is a piping diagram showing a different embodiment of the device, Fig. 3 is a piping diagram showing a conventional device, and Fig. 4 is a cell diagram of an alkaline electrolyte fuel cell. It is a voltage vs. battery temperature characteristic diagram. . 1...Fuel cell main body, 11...H33 circulation path, 21
...0! Circulation circuit, 31...N! supply passage, 41.
51... Catalytic combustor, 43... Branch pipe section, 51...
・Heating device, 52...Heat exchanger, HR...Hydrogen (fuel gas), 0! ...Oxygen (oxidant gas), N! ...
Nitrogen (inert gas).

Claims (1)

[Scope of Claims] 1) An inert gas supply passage is provided which communicates via a stop valve with two circulation circuits that supply fuel gas and oxidizing gas as reaction gases to the fuel cell main body and circulate and cool the fuel cell body. In a device that replaces a non-slip gas with a reactive gas at the time of starting up a battery, the method includes a catalytic combustor that communicates with either one of the two circulation circuits and the inert gas supply passage via a valve. 1. An alkaline electrolyte fuel cell device comprising a reactant gas heating device, wherein the fuel cell main body is preheated to a temperature at which power can be generated by the combustion heat of the mixed gas generated during the gas replacement. 2) The alkaline electrolyte fuel according to claim 1, characterized in that the reaction gas heating device comprises a catalytic combustor disposed in a branch pipe section having a stop valve in parallel with the circulation circuit. battery device. 3) In the device described in claim 1, the reaction gas heating device includes a catalytic combustor that uses purge hydrogen as a fuel gas, and a heat exchanger that uses the heat generated by the catalytic combustor as a heat source, An alkaline electrolyte fuel cell device characterized in that a heat exchanger is installed in a circulation circuit.