JPH0481488A - Production of gas sealing member - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a gas seal member for catalytically combusting an unburned mixture of gas or oil.Background ArtA conventional gas seal member is made of a sheet of heat-resistant inorganic fibers. It is used by processing it into a felt or blanket shape and compressing it and putting it in the place where you want to use it. However, with this method, it is difficult to sufficiently seal the gap between the combustion body and the frame that holds it. Therefore, in a catalytic combustion device, which is one type of combustion device, a highly concentrated unburned air-fuel mixture is supplied to a honeycomb-shaped combustion body and combusted. Unburned gas generates a strong odor. Therefore, it is necessary to pay sufficient attention to the gap between the combustion body and the frame that holds it, and conventional inorganic fiber seal members In order to improve the sealing performance, the bulk density of the gas seal member must be increased and the gas seal member must be made denser.However, in conventional gas seal members, if the bulk density is increased and the gas seal member is made denser, the gas seal member becomes As a result, the combustion body and the frame expand at a high temperature during combustion.If there is a difference in thermal expansion (generally, the frame is made of gold and the combustion body is made of ceramic). , the frame body has a larger coefficient of thermal expansion than the combustion body), a sealing member that has lost its cushioning properties creates a gap, making it easy for unburned gas to slip.We tried to prevent this with conventional gas sealing members. The present invention solves the above-mentioned conventional problems, and aims to provide a method for manufacturing a gas seal member that catalytically burns brown rice combustion gas and has appropriate cushioning properties. Means for Solving In order to achieve the above object, the method for manufacturing a gas seal member of the present invention is as follows: A sheet or felt made of heat-resistant inorganic fibers is impregnated with an aqueous solution containing a water-soluble polymer and a rare earth metal salt, and then dried. , The rare earth metal oxide can be dispersed and supported on the sheet or felt by thermal decomposition, and then the platinum group metal can be supported thereon.The present invention has the above-described structure, so that the rare earth metal oxide is evenly dispersed and supported on the inorganic fiber. EMBODIMENTS OF THE INVENTION Examples of the present invention will be described below.

Example 1 Alumina 70wt sales Silica 30wt wing fiber long fiber length 0m nail 8mm thick felt (bulk density 0.1
8 g/cc) was impregnated with an aqueous solution containing 10 wt% of polyethylene glycol (molecular weight approximately 20,000) as a water-soluble polymer and 0.1 mole of cerium nitrate as a rare earth metal salt, then rotated at 80°C for 1 hour and heat treated at 500°C for 30 minutes. and add 18wt of cerium oxide to alumina-silica fiber.
After that, this gas seal member was immersed in an aqueous solution of chloroplatinic acid, dried, and heat-treated.The gas seal member 1 obtained in this example was shown in FIG. When used in a catalytic combustion device such as Then, a combustion load of 6 kcal h/cm2 was applied to the combustion body 2, and the combustion body 2 was heated to about 800°C.
3 is a frame that holds the combustion body 2; 4 is a fuel gas supply a; 5
is the air blower a, 6 is the premixture chamber, 7 is the exhaust part, and the above combustion condition is 1 as a gas seal member life test.
After 1 cycle of extinguishing and cooling for 30 minutes, the gas sealing properties under the above combustion conditions were evaluated again after 2,000 cycles.9 Comparative Example 1 Only alumina-silica fiber was used instead of the gas seal member of Example 1. Comparative Example 1 and Comparative Example 2 The gas seal member of Comparative Example 1 was immersed in an aqueous solution of chloroplatinic acid, and subjected to rotational heat treatment. Comparative Example 3 in which a gas seal member carrying 1 wt% was used as Comparative Example 2 In Example 1, 18 wt% of cerium oxide was dispersed and supported on alumina-silica fiber using a cerium nitrate aqueous solution to which polyethylene glycol was not added. Immersed in an aqueous solution of chloroplatinic acid, rotated and heat treated 1
．． X, a gas seal member carrying 0.1 wt% platinum was used as Comparative Example 3. The sealing performance of the gas seal members obtained in Comparative Example 1, Comparative Example 2, and Comparative Example 3 was also measured under the same conditions as in Example 1. Table 1 shows the results of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 at the initial stage and after 2000 cycles.

Table 1 Results The gas seal member according to this example exhibited excellent gas sealing properties. Strength that showed excellent gas sealing properties After that, thermal deterioration progressed The catalytic metal supported on the sealing member was no longer able to exert its purification effect.
Comparative Example 3 showed almost the same level of gas sealing performance as this Example. As shown in Figures (A) and 2 (B), in Comparative Example 3, the distribution of cerium oxide was quite uneven, and the amount supported in the center was smaller than on the surface side, whereas in this example As a result, in the life test of the gas seal member, this example showed better performance than Comparative Example 3.The cerium oxide distribution in the gas seal member was made uniform. Therefore, it is effective when the amount of polyethylene glycol added to the aqueous solution is about 2 to 15 wt%.And when the molecular weight of the polyethylene glycol used is large (molecular weight of about 60,000), a small amount of about 2 to 15 wt% is added. When the molecular weight is small (molecular weight approximately 8000), it is approximately 10 to 15
About wt% is preferable.Example 2: 10wt of polyethylene glycol (molecular weight: about 20,000) as a water-soluble polymer was added to the same alumina-silica fiber felt as used in Example 1, and cerium nitrate was added as a rare earth metal salt of 0.02~ Impregnated with an aqueous solution containing 0.4 mol [rolled at 80°C for 1 hour, heat treated at 500°C for 30 minutes]
Cerium oxide was dispersed and supported, and the gas seal member was immersed in an aqueous solution of chloroplatinic acid, rotated, and heat treated. Measurements were made under the same conditions as in 1. Regarding the cushioning properties (restorability) of gas seal members: 41 Cut the member into Icm" pieces and press to 10k.
It was evaluated based on the recovery rate after applying a load of "g/cm".Here, recovery rate (%)=(thickness after load)/(thickness before load).The results are shown in Table 2.

Example 3 Bulk density 0. 29g/cc, 8mm thick alumina silica fiber felt with 10wt% polyethylene glycol (molecular weight approximately 20,000) as a water-soluble polymer.
Cerium nitrate as rare earth metal salt 0.02~0.2
Dry the aqueous solution containing 0 mol in an impregnation machine at 80℃ for 1 hour 50
Cerium oxide was dispersed and supported by heat treatment at 0°C for 30 minutes.Each gas seal member was immersed in an aqueous solution of chloroplatinic acid and then heat treated at a rolling speed (\0.1w of platinum).
The sealing performance of the obtained gas seal member was measured under the same conditions as in Example 1. The results are shown in Table 3.

(Space below) Example 4 Flumina silica fiber felt with a bulk density of 0.4 g/cc and a thickness of 8 mm was impregnated with an aqueous solution containing 10 wt% of polyethylene glycol (molecular weight 20,000) as a water-soluble polymer and cerium nitrate as a rare earth metal salt. 8
Dry at 0°C for 1 hour, heat treat at 500°C for 30 minutes to disperse and support cerium oxide, then immerse in an aqueous solution of chloroplatinic acid and perform rotational heat treatment.1. % 0.1wt platinum
The gas sealing properties of the gas sealing member loaded with 9% of the gas loading were measured under the same conditions as in Example 1.The results are shown in Table 4.

The results of Tables 2, 3, and 4 are summarized. Cerium oxide is supported on alumina-silica fiber as a glass sealing member, and it was found that excellent sealing performance was exhibited when the specific surface area was 2 m2/g or more. However, the supported cerium oxide If the amount increases, the cushioning properties (restoring properties) of the gas seal member will deteriorate rapidly, and gaps will easily form between the combustion body and the seal member, or between the seal member and the frame body, when repeatedly extinguishing a fire using a catalytic combustion device. Despite showing excellent performance in the initial stage, gas leakage occurred after the life test. Therefore, the bulk density of the gas seal member in the present invention is 0.
15-0. It is preferable to keep it in the range of 50g/cc.
Here, the bulk density of 0.15 g/cc is a value that takes into account the strength of the gas seal member, and anything less than this does not have sufficient strength and cannot be used (by the way) The heat-resistant inorganic fiber used in the present invention A sheet or felt made of heat-resistant inorganic fibers such as alumina, silica fibers, silicon carbide fibers, and silicon nitride fibers is suitable (from a cost perspective, alumina, which is currently used in a wide range of applications) Silica fiber is most preferred, and its composition is alumina 40-95.
Preferably 5 to 60 wt% silica.The reason for this is that if heat resistance is taken into consideration, it is preferable to increase the alumina content.Strength If the alumina content is too large, the fibers will become brittle. It is. In addition, considering the mechanical strength of the cushioning method for gas seal members, rare earth materials can be made using sheets or felts with a fiber length of 50 mm or more, a fiber diameter of 5 μm or less, and a bulk density of 0.15 to 0.40 g/cc. It is preferable to support a metal oxide.As described above, the present invention provides the following effects (1) Catalytic combustion of unburned gas and appropriate cushioning properties. (2) Even if a gas seal member is obtained, a combustion device can be obtained that can completely prevent unburned components leaking from the gas seal member in the gap between the combustion body and the frame that holds it. The effects of the present invention are remarkable in catalytic combustion devices including

[Brief explanation of drawings]

FIG. 1 is a cross-sectional diagram of a combustion device having a gas seal member according to an embodiment of the present invention. FIG. 2 (A) and FIG. This is a diagram analyzing the dispersion state of cerium oxide. Gas seal member. Fig. 2 Fig. Cas seal member

Claims (3)

[Claims] (1) A sheet or felt made of heat-resistant inorganic fibers is impregnated with an aqueous solution containing a water-soluble polymer and a rare earth metal salt, and then dried and pyrolyzed to disperse and support the rare earth metal oxide in the sheet or felt. A method for manufacturing a gas seal member, which comprises subsequently supporting a platinum group metal. (2) The method for manufacturing a gas seal member according to claim 1, wherein the water-soluble polymer is polyethylene glycol. (3) Manufacturing the gas seal member according to claim 1, wherein the sheet or felt has a specific surface area of 2 m^2/g or more and a bulk density of 0.15 to 0.50 g/cc. Method.