Background Art Currently, large amounts of domestic waste materials, industrial waste materials such as waste vinyl products and waste synthetic plastic from factories, medical waste materials from hospitals, radioactive waste materials, various petrochemical waste materials are discharged. The treatment of these waste materials becomes a serious social problem. These waste materials are mainly processed by means of burial or incineration. The incineration processing has advantages that the amount of finally processed waste materials can be reduced and combustion heat released during incinerating waste materials can be used for district heating, which are advantageous compared to burial processing. Accordingly, studies on various apparatuses and methods for enhancing incineration efficiency of incinerating furnaces and for reducing the amount of fuel used are actively in progress.

However, various combustion gases contaminating the atmosphere are exhausted during incinerating waste materials. Among these gases, dioxin may be generated and exhausted into the atmosphere when chemical resins such as synthetic resins are incompletely burned, causing serious environmental pollution problems.

In general, conventional incinerators are mainly composed of an incinerating furnace surrounded by a refractory material and a dust collector including a cyclone,

etc. Since the conventional incinerators exhaust combustion gases containing toxic gases into the atmosphere, there is a need to prevent the toxic gases from being exhausted into the atmosphere.

Representative examples of the combustion gases include dust, carbon dioxide, chlorinated compounds such as chlorinated hydrocarbon, NOx-based nitrogen compounds and dioxin. These gases are very harmful to the human body and environment. The chlorinated compounds are ozone-depleting materials and thus destroy the ozone layer. Dioxin is known as an endocrine disruptor, and has 1,000 times more toxic than potassium cyanide. When dioxin is accumulated in the body, the liver and the kidney are damaged, immunity drops, and skin diseases, cancers, birth of deformed children, gene mutation, etc. , may happen. Further, since accumulation rate of dioxin is very high, dioxin is seldom discharged out. Accordingly, regulation on dioxin discharge amount is reinforced worldwide.

In common waste material processing facilities and factories, a combustion air is fed into an incinerating furnace and thus incineration is performed therein. Such simple incinerators have an incinerating temperature of as low as about 500°C. Accordingly, thermal decomposition of dioxin is impossible, and thus dioxin may be discharged into the atmosphere. In order to reduce the amount of dioxin generated, an incinerator equipped with another incinerating furnace for effectively reburning first-burned gases is known. According to this incinerator, dioxin is burned at a previously set temperature and thermally decomposed. For example, Korean Patent Laid-open No. 1999-0078857 discloses the use of a stainless heater for high-temperature heating. The stainless heater, however, cannot be applied to incinerators requiring a temperature as high as 1, 000°C, and further has a disadvantage that the heater must be replaced due to its lowered heating efficiency, resulting from oxidation and corrosion after long-term use of the heater. Further, an incinerator using a gas burner to reburn waste materials is known. However, this

incinerator has a problem that it is difficult to maintain the temperature of the incinerator to be constant. In addition, there is a danger that since complete incineration of waste materials cannot be guaranteed at about 1, 000°C, toxic gases may be still discharged into the atmosphere.

Disclosure of the Invention The present inventor has conducted intensive research to solve the above- mentioned problems of conventional incinerators. As a result, the present inventor has found that when waste materials are charged into a melting furnace of an incinerator in which a plurality of heaters of different types and heating temperatures are installed and the waste materials are completely burned therein, the amount of toxic gases exhausted can be considerably reduced, and finally accomplished the present invention.

Therefore, it is an object of the present invention to provide a high- temperature waste incinerator with enhanced incineration efficiency in which waste materials can be incinerated at high temperature while maintaining the temperature to be constant.

In accordance with the present invention, there is provided a high- temperature waste incinerator comprising: an openable furnace cover 3 for supplying waste materials to be processed and having a combustion-air inlet and an exhaust-gas outlet 31 ; a furnace body 1 being closed by the furnace cover 3 and having a discharge port 11 for discharging melted waste materials; a melting furnace 2 for melting waste materials, the melting furnace being inserted into the furnace body 1 and having a discharge passage 21 formed at its bottom; and a plurality of heaters 4 and 5 of different types and heating temperatures for

heating the melting furnace 2, the plurality of heaters being inserted into the furnace cover 3 and disposed between the furnace body 1 and the melting furnace 2.

In the present invention, the heaters 4 and 6 are disposed between the furnace body 1 and the outer wall of the melting furnace 2 and heat the melting furnace 2. The heat transmitted to the melting furnace 2 melts waste materials supplied to the melting furnace 2. Since the high-temperature waste incinerator of the present invention uses heaters capable of heating to 1, 000°C or more, dioxin can be thermally decomposed and the process rate of waste materials is improved, thereby considerably saving work time. The plurality of heaters 4 and 5 of different types and heating temperatures are alternately inserted into the furnace cover 3. This arrangement of the heaters improves the incineration efficiency of the incinerator according to the present invention. Depending on types and processing rate of waste materials, power applied to the respective heaters 4 and 5 may be controlled (blocked or supplied) by a controller (not shown). Accordingly, the respective heaters are selectively heated.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a cross-sectional view schematically showing a high-temperature waste incinerator according to the present invention; and Fig. 2 is a perspective view showing the inner part of the high-temperature waste incinerator of Fig. 1 in which a plurality of heaters of different types and heating temperatures are installed.

Best Mode for Carrying Out the Invention

Hereinafter, the high-temperature waste incinerator according to the present invention will be explained in more detail with reference to the accompanying drawings.

Fig. 1 is a cross-sectional view schematically showing the high-temperature waste incinerator according to the present invention. First, waste materials are supplied to a melting furnace 2 through a furnace cover 3 by moving upwardly. The furnace cover 3 has an inlet (not shown) for feeding combustion air into the melting furnace 2 and an exhaust-gas outlet 31 for discharging exhaust gases generated by heaters in the melting furnace. The exhaust-gas outlet 31 is connected to a gas purifier 32 which separates and collects gas components and dust contained in the exhaust gases.

Examples of the waste materials supplied to the melting furnace 2 through the furnace cover 3 include, but not specially limited to, domestic wastes, industrial wastes, medical wastes, radioactive wastes, various petrochemical substances and mixtures thereof.

Before the waste materials are supplied to the melting furnace 2 through the furnace cover 3, the temperature of the melting furnace 2 is preset by heaters. The inner wall of the melting furnace 2 is made of heat-resistant ceramic so as not to be damaged at high temperature by the heaters. The waste materials are melted in the melting furnace 2 by the heaters, and the melted waste materials descend to the bottom of a furnace body 1 through a discharge passage 21.

The furnace body 1 is composed of an outer wall made of stainless steel and an inner wall made of refractory blocks. A discharge port 11 is formed at the bottom of the furnace body 1 so that the melted waste materials 6 discharged from the melting furnace 2 through the discharge passage 21 are discharged outwardly.

The plurality of heaters of different types and heating temperatures are inserted into the furnace cover 3 and disposed between the furnace body 1 and the

melting furnace 2. Heating zones of the heaters are perpendicularly positioned between the furnace body 1 and the melting furnace 2. The heaters heat the melting furnace 2 so that the melting furnace 2 melts the waste materials therein. When unmelted waste materials are accumulated to some extent at the bottom of the melting furnace 2, they are discharged from the incinerator through the furnace cover 3 by moving upwardly the furnace cover 3 and inclining the incinerator, and finally the discharged waste materials are buried.

Fig. 2 is a perspective view showing the inner part of the high-temperature waste incinerator in which the plurality of heaters 4 and 5 of different types and heating temperatures are installed. A plurality of terminal zones (non-heating zones) 4a and 5a of the respective heaters 4 and 5 are inserted into the furnace cover 3 so that a plurality of heating zones 4b and 5b are perpendicularly arranged along the inner wall of the furnace body 1, and heated by a voltage applied by an external power supply.

The heaters are SiC heaters 4 and MoSi2 heaters 5, respectively. The SiC heaters 4 and MoSiz heaters 5 are alternately inserted into the furnace cover 3.

The Sic heaters 4 are heated at a temperature of 1, 400°C or less by an externally applied voltage. The SiC heaters 4 evaporate moisture contained in the waste materials, and melt some of the waste materials having a melting point lower than the temperature. In particular, dioxin contained in the combustion gas is thermally decomposed and thus is considerably reduced the amount of dioxin formed. In addition, the SiC heaters 4 are preheated in order to improve combustion efficiency of MoSi2 heaters 5 as described below. The preheating of the SiC heaters 4 reduces the amount of electric energy supplied to the MoSi2 heaters 5.

Since molybdenum disilicide (MoSi2) has high thermal conductivity, low coefficient of thermal expansion, high melting point (2, 030°C) and excellent oxidation resistance, it is widely used as a heater material of various industrial,

experimental electric furnaces, etc. In addition, molybdenum disilicide is currently <BR> <BR> used as a heat resistant material of gas turbine, nozzle, etc. , and stably heat even when suddenly heating or cooling.

The MoSi2 heaters 5 are heated at a temperature of at least 1, 400°C by an externally applied voltage. The MoSi2 heaters 5 melt some of the waste materials having a melting point lower than the temperature. Particularly, dioxin contained in the combustion gas is thermally decomposed and thus is considerably reduced the amount of dioxin formed.

Since the SiC heaters 4 and the MoSi2 heaters 5 are connected to an external power, respectively, voltages applied to the SiC heaters 4 and the MoSi heaters 5 may be appropriately controlled by a controller (not shown) in accordance with types and melting temperatures of waste materials.

The number of these heaters is not specially limited, but can be appropriately varied depending on the capacity and dimension of the melting furnace 2.

In accordance with the high-temperature waste incinerator of the present invention, since the incineration of the waste materials are promoted by the SiC heaters 4 and subsequent the MoSi2 heaters, the incineration of waste materials is promoted and thus incineration efficiency can be improved. In particular, since the waste materials can be burned at high temperature using the MoSi2 heaters 5, harmful gases, particularly dioxin, are completely decomposed.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

In accordance with the high-temperature waste incinerator of the present invention, since waste materials are melted at a temperature of about 1, 400°C or more, complete incineration of waste materials which has been incompletely processed can

be guaranteed and thus air pollution can be effectively reduced. In addition, since waste materials are melted using heaters applied by an electric energy, fuel cost and operational cost can be saved, the incinerator can be operated in a simple manner, and constant temperature can be maintained by a controller.

Furthermore, since the power applied to the respective heaters 4 and 5 can be controlled by a controller, and the amount of electric energy supplied to the MoSi2 heaters 5 can be reduced by preheating the SiC heaters 4, combustion efficiency is improved.