JPS60151977A - Supplementary feed of electrolyte in matrix-type battery - Google Patents

Abstract

PURPOSE:To perform supplementary feed of electrolyte without downtime and complication of battery construction by connecting in parallel and disconnectably an electrolyte spraying device in an inlet pipe line of fuel gas. CONSTITUTION:An electrolyte supplementary feed system 40 includes as main constituent an electrolyte spraying device 41. The spraying device 41 is connected in parallel to a fuel gas inlet valve 32 of a fuel gas inlet pipe 31 in a fuel gas system 30 through switching valves 42, 43 disposed in front and at the back of the spraying device. The concentration of electrolyte to be sprayed by the spraying device 41 depends upon the kind of the spraying device, and in general, opening degress of the fuel gas inlet valve 32 and switching valves 42, 43 are properly adjusted so that a part or corresponding part of the fuel gas flows into the spraying device 41 to adjust the concentration of the electrolyte in the fuel gas flowing into a battery in such a manner as to be held in the range. This allows the electrolyte mixed in the fuel gas P to be penetrated into a matrix layer 1. Thus, supplementary feed of electrolyte can be performed without downtime and complication of battery construction.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention comprises a matrix and a gas layer holding an electrolyte, and a gas-diffusing reaction gas electrode layer disposed in contact with the matrix layer. , Electrolyte replenishment for a fuel cell 2, which is a layered structure in which a reaction gas passage is opened to the surface of the reaction gas electrode layer opposite to the matrix layer, for example, a matrix fuel cell using phosphoric acid as an electrolyte. Regarding the method.

[Prior art and its problems: porosity inside the battery] The so-called matrix fuel cell, in which the electrolyte is retained in the IJ layer, is
Compared to free electrolyte fuel cells, there is no need for an electrolyte circulation system, which has the advantage of simplifying the system configuration as a power generation device. It is used in batteries, but during battery operation, some amount of electrolyte is carried out of the battery by the reactive gas flowing inside the battery, and the amount of electrolyte in the battery gradually decreases, albeit slightly. The reactive gas that flows through the battery also serves to discharge water produced by the reaction and the battery's own heat generated by the power generation process to the outside of the battery, which is consumed by the battery for power generation. Since several times the required amount is passed through, the electrolyte reduction mentioned above is further promoted by this.

FIG. 1 shows the basic structure of this kind of IJ wax type cell in terms of a single cell, in which an electrolytic solution is permeated into and held in a matrix layer 1, which is usually made of a porous ceramic material. In the figure, a fuel gas electrode layer 2 and an oxidizing gas electrode layer 3 having gas diffusivity are disposed so as to sandwich this matrix layer 1 from both upper and lower ends and in direct contact with the matrix layer 1, respectively. Gas non-diffusive grooved separator plates 4, 4 having grooves 4a+'b on both sides are disposed so as to further sandwich these reaction gas electrode layers 2, 3 from the outside. A practical fuel cell stack is constructed by stacking a large number of basic structural units. Fuel gas is separator plate 4
The oxidizing gas is transferred from the fuel gas groove 4a cut in the surface in contact with the fuel gas electrode layer 2 to the oxidizing gas groove 4a cut in the direction perpendicular to the groove 4a in the opposite surface of the separator plate 4. From front 4b.

The fuel gas is supplied to the fuel gas electrode layer 2t- or the oxidant gas electrode layer 3, respectively. In a fuel cell having such a structure, the electrode layers 2 and 3 for gas diffusion of the fuel cell are disposed directly facing the grooves 4a + 'b as reaction gas passages, so that the electrode layers 2 and 3 for gas diffusion of the fuel cell are disposed directly facing the grooves 4a + 'b as reaction gas passages. The water in the electrolyte discharged into the electrode layers 2 and 3 is further evaporated into the reaction gas flowing into the grooves 4a and 4b together with the reaction product water, and at this time, some electrolyte is removed, albeit slightly. It will be mixed into the steam and carried out of the battery.

Various methods have been tried in the past to replenish the electrolyte that gradually leaks out of the cell as described above. Since the cells are isolated from the cell surface and distributed within the cell stack, no definitive good means have been found at present. The most basic method of replenishing electrolyte is to disassemble the battery body and re-impregnate the matrix and gas layers with electrolyte such as 9-phosphate using the same method used when manufacturing the battery, but this method does not completely remove the electrolyte. Even if it is possible to replenish electrolytes, electricity is not enough to replenish electrolytes. Not only would the pond have to be shut down, but replenishment work would also take a lot of effort. In order to solve this problem, attempts have been made to build in advance a t-solite replenishment structure in a large number of single cells in a cell stack. An example of such conventional means is shown in the second factor. In this example, an electrolyte reservoir 6 is provided within the separator plate 4 described above. The recess is provided at the bottom of the recess to receive the replenishing electrolyte E from the replenishment tube 7 introduced from the side of the cell stack, and the communication hole 4c provided at the bottom of the recess, the matrix layer 1 and the electrode layer. The communication hole 5 provided in the seal 5 on the periphery of 213
The electrolyte is replenished into the matrix layer l through a and n times.

In such a replenishment means, a space l for arranging the electrolyte reservoir 6 is required in the side ifu group, and the matrix layer 1 is
Since more space than is originally necessary is taken up by the 7-rule 5 on the periphery of the cell surface, there is a problem in terms of the effective cross-sectional area of the cell surface.

Furthermore, in the example shown in FIG. 2, the groove 4b for the oxidizing gas is the exit to the side surface of the cell stack.

Naturally, they will be blocked, so consideration needs to be taken such as providing communication grooves 4d between the jugs, which inevitably complicates the structure. Furthermore, since the above-mentioned unit 7 for replenishing the electric liquid must be installed in the single battery, a certain number of SE/L stars are required as a whole, and the common motherboard is divided into branches. 4-i'4
However, even if this is done, the structure will inevitably become complicated, and other problems such as corrosion caused by the electrolyte will also occur.

In addition, as a common problem when supplying 11 materials, special care must be taken to ensure that the electrolyte number does not become excessive. In other words, when the amount of solution I becomes too large, the electrolyte oozes out into the electrode layer 2.3 and the reaction residue cannot diffuse into the electrode layer, impairing the power generation function of the battery. This is because you will end up getting lost.

[Purpose of the invention]

Based on the recognition of the various problems of the above-mentioned conventional technologies,
An object of the present invention is to provide a method for replenishing electrolyte to a matrix layer distributed within a fuel cell stack without suspending battery operation or complicating the structure of the battery. .

[Key points of the invention]

According to the present invention, an electrolyte atomization device can be freely inserted and removed in parallel to the fuel sludge introduction pipe to the fuel cell in the matrix type fuel cell of the type described at the beginning. - connecting at least a portion of the gas flowing in the fuel gas introduction pipe when replenishing the M substance to the electrolyte atomization device;
This is achieved by replenishing the matrix layer with the electrolyte atomized together with the gas through the reaction gas passage and the fuel gas electrode layer.

In the above structure of the present invention, the electrolyte to be replenished is atomized and lost in the waste of the fuel gas introduction pipe to the cell.Since the amount of electrolyte is small, the amount of electrolyte mixed in is ephemeral and dilute. This electrolyte-mixed gas enters the cell compartment from the fuel sludge inlet pipe, enters the fuel gas passage in the cell body, and flows through the fuel sludge electrode layer facing the passage. The electrolyte mixed in the gas appears on the surface of the matrix layer. Initially, it was predicted that the electrolyte deposited in this way would not easily diffuse into the matrix layer, but rather would be re-splattered and discharged outside the battery compartment. However, according to experimental results, the electrolyte adhering to the anti-matrix layer side of the fuel waste electrode layer surprisingly easily diffuses to the matrix layer side, moves S, and penetrates into the matrix layer. Understood. The reason for this is that in addition to the fact that the fuel gas electrode layer is gas diffusive, the inside and vicinity of the electrode layer is moist or rich in water due to the reaction product generated during power generation, and the electrolyte is easily absorbed. It is thought that it absorbs water and penetrates into the matrix layer in the form of electrolyte and breaks down. In addition, in order to promote the transfer of this electrolyte from the fuel gas electrode layer side to the matrix and gas layer side,
It is advantageous to provide the fuel gas electrode layer with a large number of small holes or a non-water repellent narrow channel portion as described below.

In principle, the above-mentioned replenishment should be the same even if performed from the oxidizing gas electrode layer side, but according to experimental results, electrolyte replenishment from the oxidizing gas electrode layer side is not appropriate. This is considered to be because the diffusivity of the electrode layer differs between the fuel scum side and the oxidizing gas side, and the reaction catalyst contained on the oxidizing gas electrode side is easily influenced by the electrolyte concentration conditions. Therefore, the gist of the method of the present invention is to replenish the electrolyte from the fuel gas electrode side.

As can be easily seen from the above description, according to the method of the present invention, there is no or almost no need to change the cell stack configuration of the battery for electrolyte replenishment, thereby avoiding the necessary complication of the battery structure. be able to. Other advantages of the method according to the invention and its possible embodiments will be explained below.

12 Embodiments of the Invention Embodiments of the present invention will now be described in detail with reference to FIG. 1m. Fig. 3 is a system diagram showing the parts of the fuel cell power generation device related to the implementation of the method of the present invention.
is schematically shown in the center of the figure. The battery main body 10 is shown in FIG. 1, and is a rectangular columnar cell star with a large number of Hiroike units laminated and held between upper and lower holding plates ti in the figure. A manifold lid 12, partially shown in cross section, is attached to each of its four sides. Among these four manifold lids 12, from the manifold lid on the left side of the figure, oxidizing gas A1 as a reaction gas is injected into the manifold pipe 12a. The oxidizing gas enters the groove 4b, which serves as an oxidizing gas passage, from the inlet manifold formed by the method, and is supplied to the oxidizing gas electrode layer 3. This oxidizing gas A is further
b, flows to the right in the figure, enters the outlet manifold defined by the right manifold lid 12, and exits outside the battery from the outlet pipe 12b of the lid 12.

Fuel gas F is introduced into the battery from the inlet pipe 12a of the manifold lid 12 at the rear in the diagram of the battery main body IO, and similarly flows toward the front in the diagram in the groove 2a serving as a fuel gas passage. Output pipe 12b of manifold 12
Remove the battery from the Although this fuel waste system 20 is actually configured as a circulation system as is well known, it is omitted in the figure for the sake of simplicity. The fuel particles coming out of the outlet pipe 12b pass through the electrolyte tube 44, which will be described later, and exit to the left side of the figure, for example, as waste fuel gas F1, together with the waste oxidation residue AI from the oxidation gas system, to be used for fuel reformation (not shown). Used as fuel for equipment. Note that the above-mentioned fuel gas F is, for example, a reformed residue obtained by reforming natural gas and whose main component is hydrogen, which contains about 20% carbon dioxide gas.

The electrolyte replenishment system 40 necessary for implementing the method of the present invention is centered around an electrolyte atomizer 41f shown at the upper left of FIG. This electrolyte atomizer 41 is connected in parallel to the fuel sludge inlet valve 32 of the fuel gas inlet pipe 31 of the fuel gas system 30 via front and rear on-off valves 42 and 43. It can be configured as a type of atomizer.

For example, when the electrolyte is a liquid such as phosphoric acid, the electrolyte can be easily atomized into the fuel residue by directly blowing the fuel gas F into the electrolyte as a pond. Even if the electrolyte is solid, the purpose of atomization can be achieved in the same way by blowing fuel gas into the aqueous solution. Alternatively, a known atomizer using ultrasonic waves can be used, and a configuration as shown in FIG. 5, which will be described later, can also be adopted.

First, when the '1'1L solute is phosphoric acid and the operating temperature of the battery is after 18θOC8'+j, the fuel cell main body 10
The amount of electrolyte that is gradually lost from the fuel gas is about 10 to 50 milligrams per cubic meter of fuel gas supplied to the battery, so if the electrolyte is continuously replenished, the amount of It is recommended to prepare the electrolyte at a concentration of 50 ml) duram/m3. When replenishing electrolytes intermittently,
Of course, there are ways to atomize the electrolyte at a higher concentration than this, but it has been experimentally shown that if the replenishment rate is reduced too much, the power generation function of the fuel gas electrode layer will deteriorate even temporarily, so the above-mentioned It is appropriate to atomize the electrolyte into the fuel gas at a concentration of about twice that of the fuel gas, that is, 20 to 100 milligrams/m3. In any case, the concentration of electrolyte that can be atomized by the electrolyte atomizer 41 varies depending on the type of atomizer, but in many cases υ is higher than the above concentration range, so the above-mentioned fuel sludge introduction is usually Valve 32 and on-off valve 42°430
By adjusting the opening K appropriately, a part or a proportion of the fuel gas to be supplied to the battery is passed through the atomizer 41 so that the electrolyte concentration in the fuel gas entering the battery is within the above range. Adjust to.

The electrolyte mixed with the fuel gas F as described above enters the groove 2a as a fuel gas passage shown in FIG. An advantageous structure for promoting this penetration or transfer into the matrix layer 1 is shown in FIG. 4. There are some people. This figure, like the previous figure 2, shows the main part of the unit cell in cross section, and as shown in the figure, a large number of small holes 2a are provided in the part facing the gas passage groove 4a of the fuel gas electrode layer 2. ing. 'IL attached to the surface of the fuel gas electrode layer 2 through such small holes.
It has been found from experience that the transition to the M-quality matrix M1 can be accelerated, and that even if such small holes are provided, the power generation effect of the battery is not significantly affected. In addition, even if an excessive amount of electrolyte reaches the fuel gas electrode layer, the electrolyte in the electrode layer will relatively quickly move toward the matrix layer as the fuel gas diffuses into the electrode layer. Therefore, even if a slightly excessive amount of electrolyte adheres to and hides on the surface of the electrode layer during operation, the function of the electrode layer will not be particularly impaired. Another advantageous electrode layer structure may be such that instead of the small holes 2a described above, only those portions do not contain the water repellent. In this way, the electrolyte can be quickly transferred to the matrix layer 1 through the non-water repellent portion without impairing the power generation function of the electrode.

However, some of the electrolyte that has stuck to the surface of the fuel gas electrode layer 2 as described above may be re-splattered and discharged outside the battery compartment. Preferably, an electrolyte trap 44 is provided outside of 12b. The fuel waste F1 discharged from the outlet pipe 12b is
In addition to electrolytes, it also contains water produced by reactions, so
This moisture removal step is usually necessary, and the electrolyte trap 44 can be used in conjunction with such a moisture condenser. A conventional heat exchanger may be used as the condenser, and by cooling the fuel gas to the condensing temperature of water, a dilute electrolytic solution is condensed. The electrolyte in the condensed water can be removed by a known method such as neutralization, and the condensed water from which the electrolyte has been removed can be simply discarded or used as reaction water for fuel reforming.

FIG. 5 shows an example of the structure of the above-mentioned electrolyte atomizer 41 used in carrying out the present invention. In this structural example, the atomizer 41 is a single liquid storage container as shown in the figure, and an aqueous electrolyte solution, such as a phosphoric acid aqueous solution, is stored in the container 41a. A nozzle 41b is introduced into the container by penetrating the side wall of the container 41a, and from the nozzle 41b a jet of gas, for example, fuel gas, is blown as a carrier gas onto the liquid surface 41o of the electrolytic solution. The nitric acid type) is easily atomized and led out along with the residue through the upper 7-rank section 41d to the piping lined with chain gauze. Atomization is relatively easy in this way when using dissolved phosphoric acid, but it is better to atomize pure 9-phosphoric acid using an electrolyte solution containing water as described above. It is better to atomize rice in the form of atomization, and it is possible to mix a large amount of electrolyte into the carrier gas. In addition, it is effective to make the angle of the jet flow almost parallel to the liquid surface as shown in Fig. 4. Easily distribute Jig 1-j via
G in which the electrolyte can be injected from the charging port 41c.
Since IBI is enough, there is no need to be particularly careful when handling.

Figure 6 shows the electrolyte concentration per unit time (vertical axis) versus electrolyte concentration (horizontal axis) when atomizing the phosphoric acid electrolyte using the atomizer 4 in Figure 5. As mentioned above, it can be seen that the lower the concentration of the electrolyte, the better the atomization efficiency. However, because of this, when replenishing the electrolyte to the battery at operating temperature, the electrolyte may not be sufficiently attached to the fuel gas electrode layer and may be re-splattered.

For this reason, the gas containing the atomized electrolyte is heated before being supplied into the growth zone to reduce the moisture content in the atomized electrolyte.
It is desirable to supply the battery in the form of an atomized electrolyte that is as pure as possible. Of course, if the fuel gas itself has low humidity and is well dry, the above-mentioned heating may be slight or may not be necessary. FIG. 7 shows a different embodiment of the method of the present invention, in which the fuel cell main body 1
0 is schematically shown as a single cell, and matrix layer 1. Fuel gas electrode layer 2. In addition to the oxidizing gas electrode layer 3, a fuel gas compartment 10a and an oxidizing gas compartment 10b are shown. The fuel gas section lOa is the aforementioned fuel gas passage groove 4a.
You can think that. Further, the oxidizing gas system piping is completely omitted, and the same parts as in FIG. 3 are given the same reference numerals. The fuel gas F introduced from the upper left side of the figure through the large mouth valve 33 is, for example, high-pressure fuel waste supplied from a fuel reformer, and after passing through the inlet valve 33, enters the fuel gas F and expands. 1 low pressure fuel gas, fuel gas 4 pipe 3
1, the fuel gas enters the fuel gas section 10a in the battery from above, and is discharged from below, and is sucked into the defuser 34 again for circulation and detonation. The electrolyte trap 44, which also serves as a condenser for the reaction product water described above, is inserted into this circulation path. -Man' A part of the fuel gas in the circulation path here is
In the battery, along with the carbon dioxide scum that does not contain γ11 and C, it can be extracted as 1 liter of free sludge at the bottom left of the figure, and for example, fuel 1 for a fuel reformer is used as scum.

The electrolyte supply system 40 has a power structure (as shown in FIG. Fuel gas F.

The waste, which is still under reduced pressure to about d2 to 3 atmospheres, is introduced and used for converting the material into U. The fuel sludge containing electrolyte from the atomizer 41 passes through the electrolyte outlet pipe 46 and is combined with the fuel sludge in the fuel sludge special pipe 31 .

This %fif (negative 4 outlet pipe 46 can be provided with a gas heating device for increasing the concentration of the atomized electrolyte mentioned above. Also, in the above explanation, the electrolyte trap 44 is used to condense the reaction product water. Although we have shown an example in which it is inserted into the cod gas circulation path and also serves as a container, it is also possible to separate it from the condenser and install it in the waste fuel gas path shown by the chain line in the figure. be.

In both embodiments shown in FIGS. 3 and 7, the electrolyte replenishment system can be operated continuously during operation of the battery, or may be operated intermittently. In the case of intermittent operation, when the electrolyte amount in the battery decreases, a decrease in the generated aL voltage is observed, so the replenishment system starts operating when the generated voltage falls below a predetermined value. Just do it like this. Furthermore, in the case of intermittent operation, when the operation ends, it is known from experience that when the amount of electrolyte in the battery becomes too large, the firing voltage of the battery is not constant and fluctuates up and down. If even a slight fluctuation phenomenon in the WL pressure begins to be observed, it is a good idea to immediately end the replenishment operation. In addition, the amount of electrolyte retained can be determined more precisely by measuring the open circuit voltage of the battery, so for both continuous and intermittent operation, the battery operation can be stopped for a very short period of time to develop an open circuit. It is useful to measure the tortoise pressure and get a guide to electrolyte replenishment.

In the above description of the embodiment, only a mode in which a part of the fuel gas is diverted to the electrolyte atomizer was shown, but depending on the type of atomizer, it may be necessary to flow all of the fuel gas through the atomizer. In some cases, it may be desirable to shorten the replenishment time. Moreover, electrolyte replenishment according to the method of the present invention can be carried out not only while the battery is in operation. However, when replenishing the battery while the battery is out of operation, it is best to avoid supplying fuel gas to the battery while the battery is out of operation. It is necessary to use inert casseroles for this purpose.

At the time of octopus, the thermal storm is low and the electrolyte fuel sludge electrode layer is rather well maintained, but excessive shielding can be harmful, so it is important not to It is desirable to adjust the current amount by controlling the mixing of the screen and the temperature difference between the gas and the battery. If an excessive amount of adhesion occurs, the adhering electrolyte can be redispersed by sending high-temperature dry inert scum, and if the amount of adhesion is too large and fails, the adhering electrolyte can be dispersed at the start of the next operation. In many cases, it is just a question. Thus, the method of the present invention can be widely implemented in various modified forms.

〔Effect of the invention〕

As explained above, in the method of the present invention, an electrolyte atomization device is connected in parallel and detachably to the fuel gas introduction pipe to the fuel cell, and when replenishing the electrolyte, the fuel gas flows through the dedicated pipe. At least a portion of the gas is made to flow through the electrolyte atomization device, and the electrolyte atomized together with the scum is supplied to the matrix layer through the fuel gas electrode layer through the reaction gas passage, so that the structure of the battery is improved. The intended purpose of IIM quality replenishment can be achieved without making little or no change to the structure of the unit or cell stack, and there is no need to complicate the structure of the battery as in the prior art. Of course, there is no need to take any extra effort to disassemble part of the battery. In addition, as can be easily understood, according to the method of the present invention, the electrolyte is replenished all at once to the matrix layer dispersed within the cell stack of the battery, which eliminates the difficulty in replenishing the electrolyte due to the distribution of the matrix layer. Essentially resolved. Furthermore, according to the method of the present invention, it is possible for the first time to supply electrolyte at any necessary or desired time, regardless of the operating state of the battery, in a single-capacity fuel cell generator. This can greatly contribute to the highly efficient operation of

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the basic structure of a matrix-type twisted cell cell as a target for electrolyte replenishment according to the method of the present invention, and FIG. 2 is a cross-sectional view of essential parts of a fuel cell showing an example of a conventional electrolyte replenishment method. Figures 3 and 3 onwards explain embodiments of the method of the present invention, and Figure 3 is a partially cutaway cross-section and piping showing a fuel cell and attached gas system related to the electrolyte replenishment method based on the present invention. Figure 4 is a sectional view showing an example of the structure of a battery in which small holes are provided in the fuel gas electrode layer, which is advantageous for implementing the method of the present invention, and Figure 5 is an electrolyte atomizer used for implementing the method of the present invention. FIG. 6 is a graph showing the rate of atomization of electrolyte by the atomizer shown in FIG. and a systematic diagram of the attached system. In the figure, l: matrix layer, 2: fuel gas electrode layer, 3 carbon dioxide gas electrode layer, 4a: fuel as reactant gas passage. l′

Claims (1)

[Claims] 1) A matrix layer that retains an electrolyte and a gas-diffusible reactive gas electrode layer disposed in contact with the matrix layer are dispersed and incorporated, and the anti-matrix and waste layer sides of the reactive gas electrode layer are disposed in a dispersion manner. A method of replenishing electrolyte to a fuel cell formed of a stacked body having a reactant gas passage opened to the surface of the fuel cell, the method comprising: installing an electrolyte atomizer in parallel with a conduit for introducing fuel gas into the fuel cell; The device is removably connected, and when replenishing the electrolyte, at least a part of the waste flowing in the fuel gas introduction pipe is made to flow through the electrolyte atomization device, and the electrolyte atomized together with the gas is passed through the reaction gas passage. 1. A method for replenishing electrolyte for a matrix fuel cell, characterized in that the matrix layer can be replenished through a fuel gas electrode layer. 2. A method for replenishing electrolyte for a matrix-type fuel cell or a dispersion-type fuel cell according to claim 1, wherein the replenishment of electrolyte is carried out during power generation operation of the fuel cell. 3) A method for replenishing electrolyte for a matrix fuel cell according to claim 1 or 2, wherein the gas flowing through the electrolyte atomization device is a fuel gas. 4) In the method according to claim 1, the matrix type is characterized in that the electrolyte is replenished while the fuel cell is out of operation, and the gas flowing through the electrolyte atomization device is an inert gas. How to replenish electrolytes in fuel cells. 5) In the method according to claim 1, tWl
The quality is phosphoric acid, and the gas contains lO~100mg/
1. An electrolyte replenishment method for a matrix fuel cell, characterized in that the electrolyte divided into cubes of cubic meters is supplied to the fuel cell for replenishment. 6) % The method according to claim 1, characterized in that the matrix layer is supplied with electrolyte through a large number of small holes formed in a portion of the fuel gas electrode layer facing the reaction gas passage; Electrolyte replenishment method for a gas-type fuel cell.