JPS60193525A - Smoke and odor consuming apparatus of exhaust gas in electric furnace for wax type calcination - Google Patents

Abstract

PURPOSE:To prevent the pollution of a catalyst by providing a heater in a dispersion-retention chamber and a porous heat reflection plate thereon and thermally decomposing the particles and tar or the like contained in exhaust gas in a smoke and odor consuming apparatus of exhaust gas in an electric furnace for wax type calcination. CONSTITUTION:The gas flowed from an introduction port 21 is introduced to a conical dispersion-retention chamber 222 as a lower heating chamber and uniformly heated with a heater 24. Then the gas is flowed in an upper heating chamber 223 through the notched part of said heater and heated with a heater. A porous heat reflection plate 26 is provided to the upper part and the gas is passed through the narrow pores 261 of said heat reflection plate and undecomposable substance such as tarry material and soot are caught, thermally decomposed and introduced to a catalyst layer 28. Since the introduced gas is free from undecomposale substance, the catalyst is not contaminated with poison. The gas treated in said catalyst layer is sucked with a fan 361 and discharged.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a smoke and deodorization device for exhaust gas in an electric furnace for firing wax molds, and in particular, a device for eliminating smoke and deodorization for exhaust gas in a small electric furnace for dental technology. Related to deodorizing equipment.

(Background of the invention and prior art) In general, when baking plaster molds using wax in dental laboratories, etc., or producing precision castings using lost wax, in an electric furnace there is a The process produces strong-smelling gas and soot. In particular, at the start of firing, the temperature inside the furnace is low and does not reach the ignition temperature, so the line becomes evaporated and hydrocarbon gas and soot-like or tar-like partial decomposition products are generated, which are discharged from the furnace exhaust gas. Flows from the mouth. In this case, if the laboratory is small, the room will be filled with smoke with a strong odor, resulting in extremely poor environmental hygiene. Even when the exhaust gas from the exhaust port is led outside through a chimney, this exhaust gas has a strong odor, causing a pollution problem.

Therefore, various devices have been developed for deodorizing Wt11 by treating the exhaust gas placed in an electric furnace and coming out of its exhaust port. A conventional device of this type is, for example, of the type shown in FIGS.

The conventional device 10 shown in FIG. 1 attempts to burn and incinerate the exhaust gas flowing out from the exhaust port a of the electric furnace A by post-heating it with a heating wire 14 wound around a cylinder 12. Conventional devices have exposed heating wires, which are prone to deterioration due to wax decomposition products adhering to them, resulting in wire breakage in a short period of time, and the removal rate of smoke and odors, especially odors, is low. It has defects. The conventional device 10a shown in FIG. 2 is an improved version of the device @10 shown in FIG. 1, mainly for the purpose of increasing deodorizing efficiency, and uses electric heat 11i114a wound around a cylinder 12a to absorb exhaust gas. is first heated to decompose it, and then passed through a catalyst layer 16a such as PT-PTI for treatment.

Although this type of conventional equipment shows relatively good effects initially, the heating by the heating wire is limited to 300 to 500°C in order to maintain the activity of the catalyst, and this prevents soot and tar in the exhaust gas. The deodorizing effect cannot be maintained over a long period of time, and the catalyst must be replaced within six months to a year. In addition, since the heating wire is exposed, it has the same defect as the device shown in FIG. 1 that it is prone to premature disconnection.

(Object of the Invention) Therefore, the main object of the present invention is to capture and completely thermally decompose particles such as soot and tar contained in the exhaust gas flowing out from the electric furnace accompanying wax mold firing. An object of the present invention is to provide a smoke and deodorizer with stable performance that prevents catalyst contamination.

Another object of the present invention is to provide a smoke and deodorize device that is small and lightweight, robust, and inexpensive, and has a high (and stable) smoke and deodorize effect.

(Structure of the Invention) The present invention includes a conical dispersion and retention chamber disposed close to an exhaust port of an electric furnace, and a heater in which a heating wire is embedded, which is disposed above the dispersion and retention chamber and preheats exhaust gas in the dispersion and retention chamber. , a porous heat reflection plate disposed above the heater that captures particles and tar in the exhaust gas and decomposes them with the heat from the heater, and a porous heat reflection plate that guides the gas that has passed through the heat reflection plate. The catalyst layer constitutes a smoke and odor deodorizing device for exhaust gas in an ant-shaped electric furnace for calcining, thereby achieving the above-mentioned objectives.

(Example) Next, one embodiment of the smoke eliminating and deodorizing device according to the present invention shown in FIGS. 3 to 5 of the accompanying drawings will be described.

The smoke eliminating and deodorizing device 20 according to the present invention shown in FIG. 3 is used by being placed in an electric furnace A and connected to its exhaust port a, similarly to the conventional device 10 shown in FIG. . This device 20
The housing 22 is equipped with a refractory housing 22 made of ceramic or the like, and the housing 22 has an opening or exhaust gas inlet 221 at its lower portion for connection to the exhaust port. Gas flowing into the housing 22 from the inlet 221 is guided to a conical dispersion and retention chamber 222 which is a lower heating chamber. This dispersed retention chamber 222
A heating wire (not shown), such as a Kanthal wire, is placed above the
Since the embedded heater 24 is provided, the gas flowing into the dispersed residence chamber 222 flows radially through the dispersed residence chamber 222 and is uniformly heated by the heater 24 . The heater 24 is made of porous heat-resistant and food-resistant material, and is manufactured by, for example, using a porous ceramic fiber as a base material, inserting the heating wire into a sandwich shape, and firing the heated wire.
It has a planar shape as shown in the figure.

This heater 24 has a porous material as its base, but since the radiation pressure of the hot wire from the buried heating wire is applied, the gas in the dispersion and retention chamber does not permeate through the porous base of the heater 24 and rise. A notch 241 formed at the peripheral edge of the heater 24 serves as a gas passage. Gas rising through this gas passage 241 flows into an upper heating chamber 223. The lower part of this upper heating chamber 223 is constituted by the heater 24. The upper part is constituted by a porous heat reflecting plate 26 made of a heat-resistant and food-resistant material such as glass wool or ceramic wool.This heat reflecting plate 26 has a planar shape as illustrated in FIG. The heat reflecting plate 26 shown in Fig. 5 is made of refractory material with a large number of pores 261 having a diameter of about 311111, and therefore has a predetermined ventilation resistance. However, since gas can permeate, the gas that has flowed into the upper heating chamber 223 temporarily stays in the heating chamber 223 and then rises further through the pores 261 of the heat reflecting plate 26. What should be noted is that, firstly, the lower surface of the heat reflecting plate 26 is heated by the radiant heat of the heater 24 and is in a red-hot state, and secondly, the heat reflecting plate 26 remains in the gas. It functions as a filter to trap possible undecomposed substances such as tar and soot.

That is, since the temperature inside the heating chamber 223 is 700 to 800°C due to the presence of the heat reflection plate 26, tar-like substances, soot, etc. remaining in the gas and captured by the heat reflection plate 26 are ignited, and the decomposed gas , so they do not accumulate. In other words, the heat reflecting plate 26 functions as a self-cleaning filter by receiving the radiant heat from the heater 24.

Since the gas that has passed through the heat reflecting plate 26 no longer contains substances such as tar-like substances and soot, it will not poison the catalyst layer 28 even if it is introduced to the catalyst layer 28. The temperature of the gas reaching the catalyst layer is 300 to 500°C, and for example, PT-PD is used as a catalyst.
It has a sufficient concentration to activate the system when it is used.

According to the device of the invention, the catalyst 1128 is supported by the refractory housing 30.

The sleeve 30 and the sleeve 22 described above are fitted and housed in a cylinder 32 made of a metal material, for example, stainless steel, and a lid 34 having an opening at the top is attached to the cylinder 32. , on this lid body is a cylindrical body 3 provided with a fan 361.
6 is placed.

One or more through holes (not shown) are bored in the upper part of the cylindrical body 32 along its periphery, and correspond to the peripheral wall of the lid body 34 so as to align with these through holes. Through hole 341
is pierced. Reference numeral 38 designates an adapter that supports the catalyst layer 28 together with the housing 30;
The upper part is configured as a cylindrical wall 381, and the lid body 3
A through hole 341 of No. 4 is formed in the cylindrical body 32 (not shown).
Even when the fan 361 is fully opened in full synchronization with the catalyst layer, the gas that has passed through the catalyst layer can be effectively sucked by the fan 361.

The reason why the lid body 34 is provided with a through hole 341 and a through hole (not shown) corresponding to the cylinder body 32 is that by rotating the lid body 34, these through holes can be opened. In order to regulate the pox and thereby control the exhaust gas flow directed to the gas inlet 221 of the device of the invention, said opening cools the treated gas, which is still hot, and makes its release safe. It also serves as a cold air intake. fan 361
is the heater 24 arranged in the device of the present invention. The resistance provided by the heat reflecting plate 26 and the catalyst layer 28 serves to allow the gas to flow even when natural drafting of the gas is difficult.

(Smoke and deodorization test) (1) Equipment used 1) Electric furnace GC: T-door 7-ness (100V/860W) (manufactured by Shishi Dental Machinery Co., Ltd.) 2) Smoke and deodorization device shown in Figure 3 a) Dimensions Main body: Cylinder 32 part (diameter 162 x height 178 + nm) Lid body 34: Diameter 162 x height 65 ia + fan part 361
: Length 76 x Width 76 x Height 2mm b) Heater power supply 100V/260W C) Catalyst DASH-220 (2-4IR1) Spherical contact 11001111j) DASH
llooll 1j) DASH-20+a+ honeycomb catalyst) d) Fan power supply 100-115V/6W 3) Measuring equipment a) Hydrocarbon meter (model manufactured by Shimadzu Corporation) -1cM-IA-Hydrogen flame ion type) b) Recorder (Model KA61 manufactured by Rika Denki Kogyo Co., Ltd.) c) OA thermocouple (I [) Preparation of test material Commercially available dental implant material (G-G-Cristobalite) and water were mixed at a weight ratio of 1:0.33. After kneading, 4 commercially available dental wax (GC green inlay wax) (equivalent to 8A) was embedded in a No. 5 ring, and the ring after 3 hours was used as a W (wet) ring and left for 1 to 2 days. The ring was a D-ring (dry) ring.

[Aim] Firing method of test material and temperature and gas temperature measurement method Insert a pipe into the exhaust port of the electric furnace, connect the furnace exhaust port with the inlet of the smoke and deodorizer, and then turn the electric furnace on. The test material ring was fired by operation. The temperature inside the furnace was measured by recording the output of the thermal lightning pair in the furnace on a recorder.

The concentration and temperature of the treated gas were determined by placing a cylindrical tube with an inner diameter of 75 m and a height of 3001 m above the smoke and deodorizing equipment, and using a hydrocarbon meter and a measuring point 205 m above the exhaust port of the 81 smoke and deodorizing equipment. It was measured with a thermocouple and recorded with a recorder.

(W) Measurement results and discussion The measurement results are shown in Figures 6-10.

Among these figures, Figure 6 shows the case where a dry type ring is used as the test material and no catalyst is used for smoke and deodorization, and Figures 7 and 8 show dry and wet type rings respectively as the test material. The case where a spherical type catalyst (DASH-220>) is used is shown.
Figures 9 and 10 show cases in which dry and wet type rings were used as test materials, respectively, and a honeycomb type ring (DASH-20MK4S) was used as the catalyst.

Furthermore, the smoke and odor elimination rate and the maximum concentration of treated exhaust gas are 269.6% when no catalyst is used (corresponding to Figure 6).
(1600 ppm>, spherical catalyst, dry ring (corresponding to Figure 7): 93.
8% (1501) Ilm>, in case of spherical catalyst, wet ring (corresponding to Figure 8) 298.9% (1301) I
)l), For honeycomb catalyst, dry ring (equivalent to Figure 9): 99.9% (not detected), For honeycomb catalyst, wet ring (equivalent to Figure 10)
: 99.9% (15pplIl or less), which means that a sufficient smoke and deodorizing effect cannot be achieved with a heater alone, and that the initial effect is brought about by using a heater and a catalyst treatment in combination. It has been found that a honeycomb type is effective.

[Brief explanation of drawings]

Among the accompanying drawings, Figures 1 and 2 are partially cross-sectional views of a conventional smoke eliminating and deodorizing device, Figure 3 is a cutaway view of a smoke eliminating and deodorizing device according to the present invention, and Figure 4 The figure is a plan view of a heater used in the smoke eliminating and deodorizing device according to the present invention, FIG. Figures 1 to 10 are graphs showing the relationship between the temperature inside the furnace and the gas II trace as well as the temperature and concentration of the treated gas in test examples using the smoke eliminating and deodorizing device according to the present invention. Figures 7 and 8 show dry rings and wet rings fired using a spherical catalyst. Figures 9 and 10 show dry rings and wet rings fired using a honeycomb catalyst. This is a graph of the case. Electric furnace・・・・・・・・・・・・・・・・・・・・・A
(Figure 1) Exhaust port...a Exhaust gas smoke and deodorizer...20 Dispersion and retention chamber...222 Heating wire...・・・・・・・・・・・・・・・・・・Heater not shown・・・・・・・・・・・・・・・・・・・・・
・・・24 Heat reflector plate・・・・・・・・・・・・・・・
・・・・・・26 Catalyst layer・・・・・・・・・・・・・・・
・・・・・・・・・28 patents filed by Kanna
River Prefecture Figure 1 Figure 2

Claims (1)

[Claims] In an exhaust gas deodorizing device connected to the exhaust port of an electric furnace for firing wax molds, there is a conical dispersion/retention chamber located close to the exhaust port of the electric furnace, and a dispersion/retention chamber located above the dispersion/retention chamber for dispersion. A heater with embedded heating wires that preheats exhaust gas in a retention chamber, and a porous heat reflection plate that is placed above the heater to capture particles and tar in the exhaust gas and decompose them using the heat from the heater. and a catalyst layer to which the gas that has passed through the heat reflecting plate is guided.