JPS6152732B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of an indoor exhaust type fan-equipped heater, which removes nitrogen dioxide (NO ₂ ) and carbon monoxide (CO) that are generated indoors when the heater is operated. The purpose is to provide clean heating.

Recently, fan-equipped heaters that are as easy to install as portable kerosene stoves, can be installed anywhere, and provide comfortable heating with hot air have been attracting attention and are being used in households. However, the combustor of this fan-equipped heater is small and generates a large amount of heat, resulting in a high flame temperature.Furthermore, since it mainly uses the diffusion combustion method with a small amount of primary air, it generates a large amount of NOx. The concentration will be very high. This NOx, especially NO ₂ , is known to cause obstructive breathing disorders, and therefore the environmental standard value (0.04~
0.06ppm) to regulate this NO ₂ .
Furthermore, since CO is likely to be generated when igniting and extinguishing, it is desirable to have clean heating that removes these.

Conventional air purification devices mainly include electrostatic precipitators and activated carbon filters, but
These can remove airborne particles, smoke, etc., but CO2, which is most concerned about the health effects mentioned above, can be removed.
could not be removed. In addition, activated carbon can remove a small amount of NO ₂ by adsorption, but its removal capacity is small, and at high temperatures, it may desorb or adsorbed NO ₂
It has the disadvantage of reducing NO to NO and releasing NO.

Hoplacite catalysts, which are a mixture of metal oxides whose main components are copper oxide and manganese dioxide, and catalysts in which precious metals such as platinum and palladium are supported on activated carbon or activated alumina have been proposed to remove CO. . However, the activity (CO removal rate) of the hopcalite catalyst decreases in the presence of moisture.

In addition, noble metal supported catalysts cannot be used unless they are at high temperatures, so they are not practical.

The present invention enables CO2 to be released even at room temperature and in the presence of moisture.
A filter that removes NO ₂ and NO 2 is attached to a heater with a fan to remove NO ₂ and CO that are emitted into the room and provide comfortable heating.

Figure 1 is an example of a filter with an air purifying function applied to a heater with a fan.

In the figure, 1 is a harmful gas removal filter installed at the air intake port of a hot air blowing fan 2, 3 is a combustor, and 4 is a hot air blowing port. Warm air from the exhaust gas burned in the combustor 3 is blown into the room from the outlet 4, heating the room, and then passed through the harmful gas removal filter at the air intake port by the blower 3, purified, and blown into the room again. . Harmful gas removal filter 1 includes an NO ₂ removing agent made from a kneaded molded product of alkali, cement material, and powdered activated carbon, and a CO oxidation catalyst made by supporting a precious metal on the kneaded molded product of alkali, cement material, and powdered activated carbon. This configuration can be installed simultaneously or independently.

NO ₂ can be easily absorbed as nitrate or nitrite by using an alkali. The alkalis used for this NO ₂ removal include hydroxide compounds such as KOH, NaOH, and Ca(OH) ₂ , carbonates such as K ₂ CO ₃ , Na ₂ CO ₃ , and NaHCO ₃ , as well as sodium thiosulfate and urea. There are many types. All of these reactions are liquid phase reactions, and are chemical absorption reactions centered on ionic reactions in the presence of water. When NO ₂ is absorbed using a wet method, operability and maintenance are extremely poor, as it is impossible to increase the space velocity due to the need to prevent water droplets from scattering. Therefore, the present inventors have discovered that a composition obtained by solidifying an alkali and powdered activated carbon with a cement material and granulating it has excellent performance in removing NO ₂ at room temperature. FIG. 2 shows an example of the NO ₂ removal performance of a composition prepared by kneading and molding potassium carbonate/calcium hydroxide/calcium sulfate (calcined gypsum)/powdered activated carbon in a weight ratio of 3/3/2/2. This shows how the NO ₂ removal performance changes depending on the space velocity (SV) of a granulated product obtained by extrusion molding the above composition to a diameter of 3 mm. The conditions are: NO ₂ inlet concentration 1.0 to 1.2 ppm, temperature 30
°C and relative humidity of 52%. This composition absorbs and removes NO ₂ through the following reaction with NO ₂ .

6NO ₂ +K ₂ CO ₃ +2Ca(OH) ₂ →KNO ₃ +Ca
(NO ₃ ) ₂ +KNO ₂ +Ca(NO ₂ ) ₂ +2H ₂ O+CO ₂ 2N ₂ O ₃ +K ₂ CO ₃ +Ca(OH) ₂ →2KNO ₂ +Ca
(NO ₂ ) ₂ + H ₂ O + CO ₂ As mentioned above, this composition removes NO ₂ at a high removal rate, and since this removal is an absorption reaction, it has a long life and has a good ability to reduce NO ₂ → NO. This is an unprecedented and superior feature, as it does not have any cracks.

The inventors also discovered that CO at an environmental concentration level at room temperature.
As a method of purifying , platinum,
We have discovered and proposed that catalysts supported with either rhodium or ruthenium, together with palladium, or palladium alone, have excellent performance and durability under general atmospheric conditions in the coexistence of water vapor.

One example of this is a catalyst in which a kneaded molded product of potassium carbonate/powdered activated carbon/aluminate lime in a weight ratio of 1/3/6 is used as a carrier, and 0.3% by weight of each of platinum and palladium is supported on the carrier. The performance of A is shown in Figure 3. In addition, the activity evaluation conditions for catalyst A were saturated at 15°C, humidity conditions with constant absolute water content, and space velocity SV = 50000 hr ^-1 .
Measurements were made with an inlet CO concentration of 100 ppm. Figure 3 shows the temperature and temperature when changing the catalyst packed bed temperature.
The relationship with CO conversion rate was shown.

Furthermore, the performance of commercially available catalyst B, in which 0.5% by weight of palladium was supported on conventional activated carbon, under the same conditions is also shown for comparison. As is clear from FIG. 3, both A and B have significantly different catalytic activities. Conventional hopcalite-based catalysts exhibit high performance under conditions where there is no moisture, but under the conditions discussed here they did not show any conversion rate.

By combining the two types of compositions described above or by using them alone, indoor air pollution caused by combustion exhaust gas can be achieved.
CO and NO ₂ can be removed.

Note that these harmful gas removal rates have excellent performance under normal temperature general atmospheric conditions in the coexistence of water vapor, so in the case of a heater with a fan, it is desirable to install it at the air intake port of the fan. When installed at a hot air outlet, it will be heated to about 100°C, so it is possible that the powdered activated carbon in the composition will burn due to heating, which must be avoided.

Furthermore, when installing these harmful gas removers at the air intake port of the fan, it is desirable to place them behind the dust removal filter, since the porous surface may be clogged with dust.
As for a specific filling method, it may be sufficient to fill a suitable frame, but it is necessary to take care to ensure uniformity so as not to cause channeling of the air flow. For example, a conventionally known method may be used, such as sandwiching the harmful gas removing agent between nonwoven fabrics such as polypropylene to form a sandwich structure.

This polypropylene has the excellent property of having a very low moisture absorption rate, so it can be used as the NO ₂ remover mentioned above, which has excellent performance in the presence of water vapor.
By sandwiching the oxidation catalyst and creating a sandwich structure,
Moisture in the air easily accumulates between the polypropylene nonwoven fabric, NO ₂ removal agent, and CO oxidation catalyst, greatly improving performance.

With the above filter structure, it is possible to almost completely achieve the long-awaited prevention of indoor air pollution caused by fan-equipped heaters.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of a fan-equipped heater according to an embodiment of the present invention, FIG. 2 is a diagram showing the characteristics of the NO ₂ removing agent, and FIG. 3 is a diagram showing the characteristics of the CO oxidation catalyst. 1...Harmful gas removal filter, 2...Hot air blowing fan, 3...Combustor.

Claims (1)

[Scope of Claims] 1. A kneaded molded product of alkali, cement material, and powdered activated carbon as a harmful gas removal filter sandwiched between polypropylene nonwoven fabrics and configured as a sandwich sandwich in the air flow path of a heater with a built-in combustor and hot air blowing fan. A heating machine with a fan, characterized in that a NO ₂ removing agent consisting of the above, and a CO oxidation catalyst in which a precious metal catalyst is supported on a kneaded molded product of an alkali cement material and powdered activated carbon are installed singly or simultaneously. 2. The fan-equipped heater according to claim 1, wherein the harmful gas removal filter is installed at an air intake port of the heater. 3. The fan-equipped heater according to claim 1, wherein the NO ₂ removing agent as the harmful gas removing filter uses potassium carbonate and calcium hydroxide as the alkali and calcined gypsum as the cement material. 4. The CO oxidation catalyst as the harmful gas removal filter uses potassium carbonate as the alkali and lime aluminate as the cement material,
A fan-equipped heater according to claim 1, in which platinum and palladium are simultaneously supported as noble metal catalysts.