JPH0817833B2 - Fire extinguishing methods for sodium-sulfur batteries - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a fire extinguishing method for a sodium-sulfur battery, and more specifically, an abnormality occurs in the sodium-sulfur battery, which is caused by a chemical reaction of an internal active material. It relates to a method of extinguishing a fire that has occurred.

[Related Art] Recently, research and development of a high-temperature sodium-sulfur battery that operates at 300 to 400 ° C. and is excellent in both performance and economy as an electric vehicle and a secondary battery for nighttime power storage have been promoted. I have.

That is, in terms of performance, a sodium-sulfur battery has a higher theoretical energy density than a lead storage battery, there are no side effects such as the generation of hydrogen and oxygen during charge and discharge, the utilization rate of the anode active material is high, and sodium and sulfur are economically advantageous. Has the advantage of being inexpensive. By connecting a plurality of this sodium-sulfur battery in series, and further arranging a plurality of those connected in series and heating to 300 to 400 ° C., metal sodium and sulfur that are active materials are melted,
The ions of the active material are moved in a molten state, and electrochemical reactions are performed with each other to obtain a predetermined electric energy.

[Problems to be Solved by the Invention] However, the solid electrolyte tube inside the sodium-sulfur battery may be destroyed due to some circumstances such as an overcurrent flowing to the sodium-sulfur battery due to an accidental short-circuit current or the like. If it is destroyed in this way, molten metal sodium and molten sulfur, which were separated inside and outside by the solid electrolyte tube, directly contact and mix with each other to cause a chemical reaction, and the heat of reaction causes a fire in the case. .

In this case, a method of extinguishing the fire by sand cooling as a fire extinguishing agent that does not react with metallic sodium, sulfur, and the products of these chemical reactions can be used to block oxygen from the top of the case. However, the sand has an irregular shape when viewed microscopically,
There is a problem that a large number of inflow holes must be provided on the upper surface of the case in order to disperse the particles uniformly. In addition, since sand has hygroscopicity, it is necessary to preserve the sand to prevent the moisture contained in the sand from reacting with metallic sodium during fire extinguishing work, that is, to maintain the dry state so as not to absorb moisture. There was a problem that we had to be strict.

The purpose of the present invention is to control the extinguishing agent and
It is an object of the present invention to provide a method for extinguishing a fire in sodium-sulfur that can quickly extinguish a fire in a sulfur battery.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides an active material of a battery and a case of a fire in a case accommodating an assembled battery group composed of a sodium-sulfur battery. The gist is to insert a large number of ceramic spherical particles that are non-reactive with the product and have no hygroscopicity and insulation.

[Operation] With the above configuration, when spherical particles flow into the case, the molten sulfur, metallic sodium and sodium polysulfide are cooled by the ceramic spherical particles to a temperature below their respective melting points and solidify to become solid. The solidified sulfur and sodium polysulfide are inactive due to lack of reactivity.
On the other hand, metallic sodium does not supply oxygen due to the ceramic spherical particles, and the reaction with oxygen in the air is suppressed. Furthermore, ceramic spherical particles have low frictional resistance and flow.
Since it has a good diffusibility, it is easy to flow into and fill the gaps between the batteries due to its own weight, and the fire extinguishing work becomes reliable.

Further, in the present invention, since the spherical ceramic particles have an insulating property, a short circuit accident between batteries during fire extinguishing work can be prevented.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the case 2 is formed in a rectangular box shape and has a double wall structure of the inside and outside, and the heat insulating material 1 is interposed between the inside and outside walls. Case 2
A mounting table 4 is disposed on the bottom of the substrate via a support member 3. An assembled battery 5 is erected and fixed on the mounting table 4.

Although the inside of each battery pack 5 is not shown, a single sodium-sulfur battery is vertically stacked and connected in series. In the single sodium-sulfur battery, metallic sodium and sulfur are separately stored via the solid electrolyte tube. Reference numeral 6 is an electric heater provided on the bottom of the mounting table 4 and the case 2 described above.
By heating to ° C, metallic sodium and sulfur in the assembled battery 5 can be melted.

In FIG. 1, a pair of pipes 7a and 7b are provided on the upper left side of the case 2. One pipe 7a is an inflow pipe 7a for inflowing outside air, and the other pipe 7b.
Is a discharge pipe 7b for discharging the air inside the case 2. The temperature of the inside of the case 2 is maintained at about 320 ° C. by the air circulation by the pipes 7a and 7b and the heating control of the electric heater 6.

Further, a rectangular support base 8 is arranged on the left side portion of the case 2, and an upper portion thereof projects above the case 2. A storage tank 9 is placed and fixed on the upper part of the support base 8, and a plurality of supply pipes 10 extending obliquely downward to the right are provided on the lower right side of the storage tank 9 (fifth).
See figure). Further, outflow pipes 11 are provided at a lower portion of the supply pipe 10 at predetermined intervals, and the tips thereof are provided so as to penetrate the upper surface of the case 2.

Further, spherical ceramic particles S are stored in the storage tank 9 and flow into the case 2 through a supply pipe 10 and an outflow pipe 11 when a fire occurs in the case 2. Reference numeral 12 is an electromagnetic valve for flowing out the ceramic grains S from the storage tank 9 and flowing into the case 2. Further, the case 2 has a heat insulating structure so that the inside thereof is not condensed.

Next, characteristics and types of the ceramic particles S flowing into the case 2 will be described.

The grain size of the ceramic grain S is 0.6 mmφ, and 0.2 to 2.
Those within the range of 0 mmφ are suitable. The surface of the ceramic grain S is formed smooth and has a low coefficient of friction. Suitable materials include feldspar ordinary porcelain based on ordinary porcelain, alumina-containing porcelain, cristobalite porcelain, alumina porcelain, zircon porcelain, cordierite porcelain, etc. ing. In addition, these materials have no hygroscopicity and do not contain water even when left to stand.

Furthermore, although the volume resistivity of the above-mentioned materials slightly decreases with temperature, it has a volume resistivity of at least 1 MΩcm or more.

In addition, metallic sodium is hydrogen fluoride (HF), hydrogen chloride (HCl), hydrogen sulfide (H ₂ S), hydrogen (H), bromine (Br), fluorine (F), chlorine (Cl) even in the solidified state. ), Sulfur (S), mercury (Hg), water (H ₂ O), etc.
It is necessary to select the ceramic grains S that do not contain these substances.

In addition, as reaction products produced by the oxidation reaction of metallic sodium and sulfur, sulfur dioxide (SO ₂ ), sodium hydroxide (NaOH), sodium oxide (Na ₂ OH), sodium peroxide (Na ₂ O ₃ ), There are sodium sulfide (Na ₂ SO ₃ ) and carbon disulfide (CS ₂ ). Furthermore, during the oxidation reaction of the metal sodium and sulfur, oxygen in the air is oxidized due to the heat of the oxidation reaction, resulting in nitrogen oxidation. Things (NOx) etc. are generated. Therefore, it is necessary to select spherical ceramic particles S that do not react with the reaction product.

Here, for comparison, the ceramic particles S having the same particle size of 0.6 mmφ and the sand particles O having an average particle size of 0.6 mmφ are used to cover the same area. The maximum drop height was measured. On the contrary, a comparative test of the areas that can be covered when the ceramic grains S and the sand O are dropped from the same height is performed.

As shown in FIGS. 2 to 4, when covering the same area as the spreading area when the sand O is dropped from the height H with the ceramic grains S, the diffusibility is better than that of the sand O, and therefore 1 / 3H It can be seen that the ceramic grains S may be dropped from a height of some degree.

When the ceramic grains S and the sand O are dropped from the same height, the angle of repose of the sand O is 40 to 45 degrees, the angle of repose of the ceramic grains S is about 20 degrees, and the angle of repose of the ceramic grains S is about 20 degrees. It turns out that is smaller. The angle of repose refers to an angle formed by the base of an isosceles triangle and the hypotenuse connecting the base and the top when a vertical cross section is formed from the top of a truncated cone formed of sand O and ceramic grains S. Further, assuming that the spreading area when the sand O is dropped from the same height is A, the spreading area of the ceramic grains S is 7.5A.

Next, a method of extinguishing a fire of a sodium-sulfur battery will be described.

When the temperature inside Case 2 is kept at about 320 ℃,
The metallic sodium and sulfur of the sodium-sulfur battery that constitutes the assembled battery 5 are in a molten state.

Here, if the solid electrolyte tube of the sodium-sulfur battery that constitutes the assembled battery 5 is damaged for some reason, the molten metal sodium in the solid electrolyte tube and the molten sulfur in the anode container directly contact and mix with each other. Then, the following chemical reaction is performed as a main reaction, and sodium polysulfide is produced, particularly, finally, disodium sulfide.

2Na + XS → Na ₂ Sx At this time, a large amount of heat of chemical reaction is generated and the case of the assembled battery 5 is damaged.
Spills in. Then, the metallic sodium further reacts with oxygen and the like in the air to reach a high temperature state and destroys the other assembled batteries 5.

Therefore, when a sensor (not shown) in the case 2, for example, a heat sensor, a gas sensor that detects gas when a fire occurs, or the like detects this abnormal situation, the control device causes the inflow pipe 7a,
The exhaust pipe 7b is closed to stop the air circulation and stop the heating of the electric heater 6. Then, the solenoid valve 12 provided on the supply pipe 10 is opened, and the ceramic particles S are discharged from the storage tank 9. Then, the ceramic grains S are supplied to the case 2 through the supply pipe 10 and the outflow pipe 11.
It flows in and is filled.

Then, since the ceramic particles S have a high thermal conductivity, the metallic sodium and sulfur flowing out into the case 2 are quickly cooled. As a result, the sulfur is deprived of heat and solidifies, and the chemical reaction is stopped, so that it becomes a chemically safe substance. On the other hand, sodium metal is also deprived of heat and solidifies. Further, since the ceramic particles S cover the entire metallic sodium that has reacted with oxygen and moisture in the air, these chemical reactions are suppressed. As a result, the chemical reaction of metallic sodium and sulfur can be stopped to extinguish the fire. Furthermore, the ceramic particles S do not react chemically with metallic sodium and sulfur, and the ceramic particles S do not chemically react with sulfur, which is safe.

In addition, since the ceramic particles S have no hygroscopicity, they do not chemically react with water or the like and do not become a new fire source. Furthermore, when the ceramic grains S are stored in the storage tank 9, storage management is easy.

On the other hand, if sand O is used, it is necessary to provide the outflow pipes 11 at intervals L on the upper surface of the case 2 in order to uniformly diffuse the sand O considering the angle of repose as shown in FIGS.

However, in the present embodiment, as shown in FIGS. 5 and 6, the ceramic particles S have good diffusivity, and the outflow pipes 11 provided on the upper surface of the case 2 may be provided at intervals of 2.75L. As a result, it is about 1/6 that of the case where the sand O flows out from the outflow pipe 11.
It is possible to simplify the structure of the equipment because it can be reduced to the extent.

Furthermore, when covering the same area, 1 / H of the drop point height H of sand O
It suffices to drop the ceramic particles S from a height of about 3,
Since the point where the ceramic particles S are dropped from the upper part of the case 2 can be lowered, the supply structure of the ceramic particles S can be made compact as a whole.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be arbitrarily modified within a range not departing from the spirit of the present invention.

[Effects of the Invention] As described in detail above, according to the present invention, since the ceramic spherical particles do not react with metallic sodium, sulfur and products of these chemical reactions at all, the safety at the time of extinguishing is improved. The effect of reliably extinguishing the fire of the assembled battery is provided.

Further, since the ceramic spherical particles have no hygroscopicity, storage management thereof is easy, and since the ceramic spherical particles have good diffusibility, the facility structure for supplying can be simplified.

Furthermore, even if sodium and sulfur react violently with each other, the ceramic particles do not melt due to the temperature, so spherical particles with fluidity and diffusibility are quickly and reliably filled in the gaps between the cells, and fire extinguishing work is also possible from this point. It can be done reliably.

Furthermore, since the ceramic particles have an insulating property, it is possible to prevent a short circuit between batteries during a fire extinguishing operation.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of the present invention, FIG. 2 is an explanatory view showing the relationship between the spread area and height of ceramic particles and sand, and FIG. 3 is an explanatory view showing the angle of repose of ceramic particles and sand. The figure is an explanatory view showing the relationship between the spread area of sand and ceramic grains when the heights of the dropping points are the same, Fig. 5 is an explanatory diagram in which the outflow pipe is provided in the case when ceramic grains are used, and Fig. 6 is FIG. 5 is an explanatory view showing diffusion of ceramic particles based on FIG. 5, FIG. 7 is an explanatory view showing an outflow pipe provided in a case when sand is used, and FIG. 8 is an explanatory view showing diffusion of sand based on FIG. is there. 2 ... Case, 5 ... Assembly battery, S ... Ceramic spherical particles.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Kato, 11 examiner, Hidehiro Sumita, 9 Kiba-cho, Minato-ku, Nagoya-shi, Aichi (56) Reference JP-A-64-70081 (JP, A)

Claims (1)

[Claims] 1. A case containing an assembled battery group composed of a sodium-sulfur battery, which is non-reactive with the active material of the battery and a product at the time of a fire, has no hygroscopic property, and has an insulating property. A method for extinguishing a fire in a sodium-sulfur battery, characterized in that a large number of spherical ceramic particles having the above are added by making use of their fluidity and diffusibility.