JPH062822A - Flame diminishing element - Google Patents

Abstract

PURPOSE:To provide a superior heat-resistance, a high flame diminishing performance and enable passage of combustible gas at high flow rate with a safe and single quenching element by a method wherein the quenching element is made of heat-resistant ceramic porous material having some contious voids. CONSTITUTION:As heat-resistance ceramic material to be used in a quenching element, CaO, MgO, SnO2, ZnO, SiO2, Al2O3, ZrO2 and TiO2 are utilized. Ceramic powder has a particle diameter of 20mum or less in order to facilitate sintering during its baking work, organic porous material is distributed and kneaded with water to form plastic soft clay. This clay is formed into a certain shape, dried to form a green body, the green body is preliminary heated and the porous forming material is ignited and oxidized, thereafter the material is baked at such a temperature as one capable of being baked and then a porous sintered material having some communicating holes with narrow distribution of porous diameter is attained. This sintered material is formed as the flame diminishing element 4. With such an arrangement, the quenching element of large-sized sintered material for high flow rate with a less pressure loss can be easily attained. The quenching element 4 is foxed and engaged with a hollow part 2 within each of an inlet port member 10 and an outlet port member 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extinguishing element of a dry cutout used in a flame generating device or the like in which a combustible gas and a supporting gas are mixed and burned in advance.

[0002]

2. Description of the Related Art A dry cutout is connected to a combustible gas pipe of a combustion apparatus or device that burns a mixed gas of a combustible gas and a combustion-supporting gas to obtain a high-temperature flame during combustion. In addition, it is intended to prevent the flame from flowing backward in the heatable gas pipe due to the backfire of the combustion device.

In the dry cutout, for example, as shown in FIG. 1, a hollow portion 2 formed by screwing the opening of the inlet side member 10 and the opening of the outlet side member 11 of the cutout 1 concerned. Inside the porous cylindrical flame-extinguishing element 4, one end face of the flame-extinguishing element 4 was brought into contact with the inner end face inside the opening of the inlet side member 10, and the other end face of the flame quenching element 4 was fixed inside the opening of the outlet side member 11. It is fixed and locked so as to abut the plate surface of the barrier plate 6.
Then, the combustible gas entering from the inlet 2 permeates through the continuous pores of the cylinder wall from the hollow portion of the flame-extinguishing element and exits to the outer periphery of the cylinder, and the outer peripheral end of the barrier plate 6 and the inner wall of the outlet-side member 11 are separated. It passes through the gap and exits to the exit 7. Entrance 2
Is connected to a gas supply source, and the outlet 7 is connected to a combustion device. When used, even if the combustion flame surface due to a backfire from the combustion device reaches the outer circumference of the cylindrical body of the quenching element 4, the flame is not generated. Since it cannot pass through the pores of the cylinder wall and is extinguished,
It is possible to prevent a serious disaster such as explosion of a container such as a flammable gas source such as a gas cylinder.

The conventional flame-extinguishing element has been obtained by compression-molding a stainless steel powder into a cylindrical porous body and firing it into a sintered body. Regarding the manufacturing method of the ceramic porous body, the present applicant has already kneaded the ceramic fine powder and the plant organic material powder and extruded them, then burned and removed the organic matter by pre-baking, and then fired at a high temperature. , A method for producing a ceramic porous body having continuous pores has been proposed (JP-A-1-160880).

[0005]

The characteristics required of the flame-extinguishing element are that combustion or detonation due to flashback can be reliably prevented, and pressure loss through the passage of flammable gas is small.

The types of flashback are roughly classified into those in which the combustion flame surface of the combustion reaction goes up in the pipe and those in which the detonation wave front propagates at supersonic speed. The maximum pore size of the porous body that can prevent backfire by the flame extinguishing element is generally determined by the combination of the type with the volatile gas and the type of backfire.

To reduce the pressure loss of gas passage,
It is convenient to increase the pore size, but if there is a limit to the pore size as described above, in the cylindrical flame extinguishing element,
There is no choice but to increase the porosity or increase the length shape to increase the gas passage area.

In a conventional flame-extinguishing element obtained by sintering a press-molded body of stainless steel powder, only the both ends of the cylindrical body which is pressed (pressed) by the press is densely solidified, but the pressing force is reduced in the central part and the sparseness is reduced. Therefore, the pore diameter at the center of the sintered porous body is larger than the pore diameter at the ends. In general, a metal sintered body has a wide pore size distribution, so if the maximum pore size required for quenching is regulated, the average pore size becomes relatively small, and the maximum porosity obtained is about 40%. Therefore, there is a problem that the flammable gas ventilation resistance increases. Therefore, in a safety device that uses a large amount of gas,
It is necessary to connect a plurality of cylindrical unit extinguishing elements in series with each other in series or to use them in parallel, inevitably increasing the size and weight of the safety device, and ensuring the end surface joining of multiple extinguishing elements. Had to do.

The present invention utilizes a ceramic-based porous material, has excellent heat resistance, has high flame-extinguishing performance, is safe, and enables a large flow rate of flammable gas to flow through a single flame-extinguishing element. It is intended to provide an element.

[0010]

The flame-extinguishing element of the present invention is characterized by comprising a heat-resistant ceramic porous body having continuous pores.

The heat-resistant ceramic material used in the flame-extinguishing element of the present invention includes CaO, MgO, SnO ₂ and Zn.
A compound containing O, SiO ₂ , Al ₂ O ₃ , ZrO ₂ or TiO ₂ alone as a main component, or an oxide compounded with these as a main component is used.
Further, P ₂ O ₅ may be mixed. Alumina alone, zirconia alone (partially stabilized or stabilized zirconia), a mixture of alumina and zirconia, zirconium phosphate, and aluminum titanate are preferable because they have excellent heat resistance and thermal shock resistance. Especially aluminum titanate (Al ₂
O ₃ · TiO ₂ ) has a high strength at high temperature, a maximum operating temperature of 1600 ° C. or higher, and a thermal expansion coefficient of 1 × 10 ^−6.
It is suitable for flame-extinguishing elements because it is small at less than / ° C and has excellent thermal shock resistance and is inexpensive. Further, a mixture of alumina and aluminum titanate is preferably used.

Further, as other ceramic materials, Na ₂ O, K ₂ O, Li ₂ O, CaO, M as alkaline components are used.
An oxide-based glass or a crystallized glass containing any one or more of gO and one or more of Al ₂ O ₃ , SiO ₂ , B ₂ O ₃ or P ₂ O ₅ as an acidic component is also used. It Quartz glass is also preferably used because it has excellent thermal shock resistance.

Further, SiC, Si ₃ N ₄ , AlN, B
Non-oxide ceramic materials such as N, B ₄ C, TiC, TiN, TiB ₂ and SIALON are also preferably applied.

A ceramic material formed by mixing a metal or an alloy with the above ceramic material is also appropriately used. An example is a sintered body of a mixed powder of zirconia and stainless steel.

The ceramic extinguishing element of the present invention is manufactured as follows. The ceramic raw material powder prepared to have a predetermined particle size is shaped into a predetermined shape such as a cylinder by a semi-dry pressing method, a hydrostatic pressing method, a casting method, an extrusion molding method or an injection molding method, and a gas furnace, an electric furnace. Alternatively, it is fired at a high temperature using an induction heating furnace to obtain a flame-extinguishing element.

The ceramic powder has a particle size of 20 μm or less, preferably 10 μm or less in order to facilitate sintering during firing, and an organic pore-forming material is mixed and kneaded with water to obtain a plastic soft kneaded clay. This pore-forming material is incinerated and removed in the subsequent firing process, and the burnt pores become continuous pores,
It increases the porosity. As the pore-forming material, fine powder of synthetic resin or fine powder of natural plant-based organic material is used. The kneaded material is shaped by a semi-dry pressing method, an extrusion molding method, or the like, or formed into a slurry by a casting method, and when water remains, it is dried later to obtain a green body.

This green body is first preheated,
The mixed pore-forming material such as a plant-based organic material is burned and oxidized, and then fired at a temperature at which sintering is possible to obtain a porous sintered body.
This sintered body is used as a flame extinguishing element.

[0018]

Since the flame-extinguishing element made of the porous ceramic of the present invention has continuous pores, it can pass a combustible gas, and its pore diameter is 1 to 100 μm in the central pore diameter.
m, preferably 3 to 50 μm, and when flashback occurs,
As the reverse flame cools as it passes through its pores, the flame radicals lose activity and the flame disappears.

When the pore diameter is small, the flame is effectively extinguished, but the pressure loss becomes high and the supply flow rate of the combustible gas is limited. On the other hand, if the pore diameter is large, the pressure loss of the combustible gas is small, which is convenient, but there is a risk that the reverse flame will pass through the pores and further go up. In general, when the mixed gas is detonating, for example, in the case of acetylene-oxygen gas or the like, a median pore diameter of 1 to 10 μm is suitable, and when the mixed gas has a slow burning rate, for example, in methane-oxygen gas or the like,
It may be 10 to 50 μm.

The porosity of the ceramic flame-extinguishing element is 30 to.
The range is 90%, but a range of 40-80% is particularly preferred. If the porosity is less than 30%, there is a problem that the pressure loss of the flammable gas passing through becomes large, while if it exceeds 90%,
The strength of the flame-extinguishing element is reduced, and there is a risk that the element will be damaged by the impact during flashback.

It is important for the flame-extinguishing element that the pore size distribution of continuous pores is as narrow as possible, and the quenching ability is generally determined by the maximum pore size, while the ventilation resistance is determined by the average pore size. By forming the ceramic cylindrical body having a narrow pore size distribution, it becomes easy to form a flammable gas quenching element having a large flow rate.

In any of the above-mentioned molding methods, a plastic kneaded clay in which a ceramic material is kneaded with a little water, a slurry dispersed in a large amount of water, or a mixture under kneading of a thermoplastic synthetic resin powder and a ceramic powder is used. Since the molding is performed at a relatively low pressure, the ceramic particles are uniformly filled at the time of molding, and the fired product of the molded body is also a porous body having communicating pores with a narrow pore size distribution. Therefore, the calcined product has a large number of continuous pores having a pore diameter close to the maximum pore diameter that determines the flame-extinguishing ability, and the pore diameter distribution is narrow, resulting in a small pressure loss. Even when the ceramic flame-extinguishing element manufactured by such a molding method is increased in size, it is easy to narrow the pore size distribution.

In particular, when the extinguishing element is an extrusion-molded product or a cast-molded product from kneaded clay containing a pore-forming material such as plant-based organic fine particles, the water and the organic particles give plasticity during molding, and the moldability is improved. Well, the density is high, and the burning traces of the organic particles become pores during firing, which causes rearrangement due to the sintering reaction of the pores and the ceramic particle group during the sintering process, and a stable continuous pore with a narrow pore size distribution can be obtained. ,
Furthermore, the porosity of the sintered body can be adjusted in a wide range by adjusting the compounding ratio of the organic particle material.

[0024]

EXAMPLE As a ceramic, aluminum titanate (Example 1), alumina (Example 2) and zirconia-
Three types of stainless steel mixtures (Example 3) were selected to prepare flame-extinguishing elements, and flashback tests and tests of strength and pressure loss were performed.

The fire extinguishing element was tested for pore diameter, porosity, strength and pressure loss, and a flashback test was conducted.

The pore diameter was determined by crushing a part of a cylindrical sintered body into a granular material, and using a mercury press-in method (measuring instrument; Micromeritics Poisizer 9130 type), the center of volume conversion. The pore size was calculated and used as the pore size. That is, in the integrated pore size distribution obtained from the measured values of the pore size D and the pore volume shown in the following equation, the pore size corresponding to the median value (50%) of the pore volume was determined. D = −4σ · cos θ / P where D is the pore diameter and σ is the mercury surface tension (473 dyn).
e / cm), θ is the contact angle of mercury with respect to the sample (130
°) and P indicate the applied pressure of mercury, respectively.

The porosity is the dry weight W of the fire extinguishing element sintered body.
₁ (g), underwater weight W ₂ (g), and water content weight W
₃ (g) was measured and calculated from the following formula. Porosity _{= ((W 3 -W 1)} / (W 3 -W 2)) × 100
(%)

For the strength, a radial crushing strength test was conducted using a 50 mm long cylindrical sintered body as a sample (head speed: 0.5 mm /
min) The average value of 10 measured values was used.

The pressure loss was measured using a cylindrical sintered body in accordance with the Industrial Safety Research Institute's technical guideline “Dry cutout device guide for gas welding cutting work” (published on March 20, 1990).

The flashback test was carried out in accordance with the same technical guideline of the Institute of Industrial Safety as above. As a mixed gas, a mixed gas having a pressure of 2 kg / cm ² is mixed with acetylene and oxygen in Examples 1 and 2 described later, and in Example 3 in a stoichiometric ratio of complete combustion of hydrogen and oxygen. It was used.

Example 1 As a ceramic raw material powder, aluminum titanate (Al ₂ O ₃ .TiO 3) having a particle size of 3 μm was used.
₂ ) was used, and 100 parts by weight of this ceramic raw material, 5 parts by weight of methyl cellulose as a binder, potato starch (10 μm in particle size) and rice husks (5 as a pore-forming material).
0 μm) was blended as shown in Table 1 and kneaded with predetermined water to obtain a kneaded clay. This kneaded material was made into a cylindrical molded body by a twin-screw extruder and heated and dried, and this dried body was preheated at 450 ° C. for 4 hours to burn off organic matter in the dried body, and then 1450. Firing was performed at 0 ° C. for the firing time shown in Table 1 to obtain a cylindrical sintered body. Outer diameter of the sintered body is 60
mm, inner diameter 50 mm, length 100 mm.

Tests were carried out using the above sintered bodies, and the results are summarized in Table 1.

[0033]

[Table 1]

In Table 1, the pore size (1 to 4) was obtained by adjusting the firing time while keeping the composition of the pore-forming material constant.
(μm) and porosity (30 to 50%) could be adjusted (test numbers 1 to 4). The flame-extinguishing element of Sample No. 4, which had a long firing time, failed the flashback test. However, if the firing time is shortened and the porosity is increased, the pressure loss and the strength are reduced, but the flashback fires. The test passed.

(Example 2) As a ceramic material powder,
Alumina (Al ₂ O ₃ ) alone having a particle size of 0.4 μm is 100
Based on parts by weight, potato starch (particle size 10 μm, gelatinization temperature 70.5 ° C.) and rice husk (particle size 5) were used as binders.
0 μm) was blended as shown in Table 2, and a predetermined amount of water was added to obtain a slurry. The slurry was poured into a cylindrical gap having a core, subjected to a moist heat treatment at 75 ° C. for 10 hours, and further dried at 75 ° C. for 10 hours to obtain a dried body.

This dried product was inserted into a gas furnace and heated at 400 ° C. for 3 hours.
After preheating for h to burn off the organic components, baking was performed for 3 h at the predetermined temperature shown in Table 2. Outer diameter of fired body is 30m
m, inner diameter 20 mm, length 50 mm were processed and tested. The results are shown in Table 2.

[0037]

[Table 2]

As shown in Table 2, in the firing temperature range of 1450 to 1550 ° C. of the alumina flame-extinguishing element, the pore diameter is approximately constant at about 2 μm, but in the low temperature firing product (test numbers 6 and 9),
Porosity is large, radial crushing strength is small, flashback test
It was rejected due to the generation of cracks. The alumina extinguishing element was able to secure the radial crushing strength by being fired at a high temperature, and could be sufficiently used as the extinguishing element.

Example 3 Next, a sintered body of a mixture of ceramic and metal was investigated. As ceramic material powder,
Partially stabilized zirconia with a particle size of 0.3 μm (Y ₂ O ₃ 3 mol% blended) and stainless steel powder with a particle size of 4 μm were blended as metal powder, and 10 parts by weight of potato starch was added to 100 parts by weight of this mixture. Part, hydroxymethyl cellulose 5
By weight, the amount of rice husks added as a pore-forming material was selected so that the porosity after firing was 55%, and the mixture was kneaded with water to obtain a kneaded clay.

This kneaded material was extruded into a cylindrical body by a twin-screw extruder and then dried naturally and heated to obtain a dried body. The dried product was pre-baked at 500 ° C. for 5 hours and subsequently baked at 1350 ° C. for 6 hours in a hydrogen reducing atmosphere to give an outer diameter of 70 mm, an inner diameter of about 30 mm and a length of about 120 mm.
Of the sintered body.

The flashback test was carried out by using a mixed gas of hydrogen and oxygen in a stoichiometric ratio. The test results are summarized in Table 3.

[0042]

[Table 3]

Table 3 shows that even if the mixing ratio of zirconia and stainless steel is changed, it can be used as a quenching element for an oxyhydrogen flame.

[0044]

When the flame-extinguishing element made of the heat-resistant ceramic porous body having continuous pores of the present invention is implemented, the following effects can be obtained.

Since it is easy to control the pore size distribution of the ceramic flame-extinguishing element to a narrow range over the entire flame-extinguishing element, it is determined by the mixed gas as compared with the flame-extinguishing element of the same shape made of sintered metal. The pore diameter can be controlled to be equal to or smaller than the maximum pore diameter, and the pressure loss can be reduced. Further, since the size and shape and the porosity can be controlled in a wide range independently of the pore diameter of the flame extinguishing element, it is possible to easily and inexpensively provide the flame extinguishing element of a large sintered body for a large flow rate with a small pressure loss. You can

Since the ceramic sintered body has a smaller specific gravity than the sintered metal, it is light in weight, and a small portable dry type safety device can be made light in weight. Since the bonded body has excellent corrosion resistance, it has an advantage of having a long life.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a dry cutout.

[Explanation of symbols]

 1 Safety device main body 2 Gas inlet 4 Flame suppression element 5 Barrier plate 7 Gas outlet

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshio Shimada 1-5 Doyama-cho, Kita-ku, Osaka City High-pressure gas industry Co., Ltd. (72) Inventor Masayuki Sado 2-12-21 Tomobuchi-cho, Miyakojima-ku, Osaka No. 303 (72) Minoru Tomasasa Mano 6-8-304 Kanebocho, Hofu City, Yamaguchi Prefecture (72) Inventor Masanobu Masaki 99-1 Shinkita, Higashi Osaka City Koan Research Institute of Technology

Claims (5)

[Claims] 1. A flame-retardant fire-extinguishing element comprising a heat-resistant ceramic-based porous body having continuous pores. 2. The ceramic-based porous body has a pore diameter of 1
The flame-extinguishing device according to claim 1, which has a porosity of 40 to 80%. 3. The flame-extinguishing element according to claim 2, wherein the ceramic-based porous body is a fired cylindrical body formed by extrusion molding or casting molding. 4. The quenching element according to claim 2, wherein the ceramic-based porous body is a sintered body of alumina alone, a mixture of alumina and zirconia, aluminum titanate alone or a mixture of alumina and aluminum titanate. . 5. The flame extinguishing element according to claim 1, wherein the ceramic-based porous body is a fired body of a mixture of ceramic fine powder and stainless steel fine powder.