Patent Application
20130223471
The present invention relates, in general, to a metal sector having a curved inner surface and a cold crucible induction melter having the same and, more particularly, to a metal sector forming a wall of a melter which can prevent an electric arc from being generated and enhance the operational efficiency of the melter, and a cold crucible induction melter having the metal sector.
Generally, a cold crucible induction melter (CCIM) has a cylindrical melting chamber which comprises a plurality of metal sectors along which coolant circulates. The metal sectors are insulated by insulators interposed therebetween. A high-frequency induction coil is provided outside the melting chamber to provide power required to melt a substance contained in the melting chamber.
Representative examples of cold crucible induction melters in which metal sectors form a wall of a melter and electrical insulators are interposed between the metal sectors were proposed in U.S. Pat. No. 4,923,508 (Date of patent: May 8, 1990), No. 4,738,713 (Date of patent: Apr. 19, 1988), and No. 6,996,153 (Date of patent: Feb. 7, 2006).
In such a cold crucible induction melter, high-frequency current is applied to an induction coil to melt a substance in the melter. The wall of the melter includes a plurality of metal sectors which are insulated by the insulators to restrict induced current and ensure relative penetrability of an electromagnetic field.
Furthermore, each metal sector is cooled by circulation of coolant to maintain the wall of the melter at a predetermined temperature. During a vitrification process of waste, molten glass which makes contact with the wall of the melter is solidified, thus forming a thin layer so that the sealing performance of the melter is ensured.
As such, the metal sector is made of metal which has electromagnetic field penetrability, but metal causes generation of heat from induction current, resulting in a reduction of operational efficiency of the melter.
To avoid these problems, the metal sector must restrict induced current and prevent an electric arc from being generated between the metal sectors.
Given this, the shape of the metal sector is designed such that the size thereof is as small as possible to minimize generation of induced current, or to prevent an electric arc from being generated. Typically, the cross-sectional shape of the metal sector is rhomboidal or trapezoidal, and corners of the metal sector are rounded.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a metal sector which has a curved inner surface and is able to prevent an electric arc from being generated and enhance the operational efficiency of the melter, and a cold crucible induction melter having the metal sector.
In order to accomplish the above object, the present invention provides a cold crucible induction melter, including a wall formed of a plurality of metal sectors insulated by an insulator, wherein each of the metal sectors comprises: an inner curved portion forming an inner surface of the wall, the inner curved portion being convex inward relative to the wall; an outer planar portion forming an outer surface of the wall; and a side planar portion connecting the inner curved portion to the outer planar portion.
In the cold crucible induction melter having the above-mentioned characteristics, a cooling passage may be longitudinally formed in each of the metal sectors, wherein the cooling passages of the adjacent metal sectors making a pair may be connected to each other.
Alternatively, a cooling passage may be longitudinally formed in each of the metal sectors, and the cooling passage may include a cooling tube provided outside the wall and connected to the cooling passage.
The number of cooling tubes may be equal to the number of metal sectors, wherein each of the cooling tubes may be connected to the cooling passage of the corresponding single sector.
In a metal sector and a cold crucible induction melter having the metal sectors according to the present invention, each metal sector includes an inner curved portion which forms the inner surface of a wall of the melter and is convex inward relative to the wall, and an outer planar portion and side planar portions which are connected to the inner curved portion and respectively form the outer surface and side surfaces of the wall. The metal sector can prevent an electric arc from being generated. Furthermore, only a single cooling passage along which coolant for cooling the sector circulates is formed in each metal sector. Thereby, the size of the metal sector can be minimized, thus enhancing the operational efficiency of the melter.
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.
Metal sectors according to the present invention form a wall of a cold crucible induction melter (hereinafter referred to as a “melter”). Each metal sector includes an inner curved portion 111 which is convex inward relative to the wall 100 and forms an inner surface of the wall 100, an outer planar portion 112 which forms an outer surface of the wall 100, and side planar portions 113 and 114 which connect the inner curved portion 111 and the outer planar portion 112 to each other.
In the present invention, the metal sector generally has a bar shape. A cooling passage is longitudinally formed in the metal sector so that coolant circulates along the cooling passage and cools the wall of the melter.
In detail, refer to
At least one cooling passage 115 is longitudinally formed in each sector 110, and coolant circulates along the cooling passage 115 to cool the wall of the melter.
Corners where the outer planar portion 112 meets the side planar portions 113 and 114 may be rounded or chamfered.
The material of each sector may be stainless steel. An insulator is provided between adjacent sectors so that the sectors are electrically insulated from each other. Preferably, the electrical insulation between the sectors can be realized by an insulation layer 120 which covers at least the inner curved portions 111 and the side planar portions 113 and 114 of the sectors.
Different kinds of materials can be used to fabricate the insulation layer 120, so long as they have excellent electrical insulating properties. Preferably, the insulation layer 120 may be made of alumina, zirconia, zirconium, etc. which has not only excellent electrical insulating properties but also superior abrasion and corrosion resistance so that it can be effectively used as an insulator. The insulation layer 120 functions to buffer heat as well as having the electrical insulation function. Meanwhile, a surface 111 of the portion of the sector to which the insulation layer 120 is applied is an uneven surface or has comparatively high roughness so that the coating ability of the insulation layer 120 can be enhanced.
Referring to
As stated above, a hollow space along which coolant circulates is longitudinally formed in each sector. Particularly, each metal sector according to the present invention is characterized in that only a single hollow space along which coolant circulates is formed in each metal sector.
The reason for this is because the sector can be sufficiently cooled just by using one hollow space, and the size of the metal sector can be reduced, compared to a metal sector having two or more hollow spaces along which coolant circulates.
Furthermore, unlike the conventional metal sector which requires two hollow spaces in each sector for inflow and discharge of coolant, the metal sector of the present invention can circulate coolant using only a single hollow space. Thus, when the sector is designed, it is easy to change the size of the cooling passage in response to a flow rate of coolant without changing the entire size of the sector. Therefore, the degree of freedom in design can be increased. In addition, absorption of induced currents in the wall of the melter can be minimized, and the operational efficiency of the melter can be enhanced.
Referring to
In detail, the adjacent sectors 310 and 320 which make a pair respectively have a first cooling passage 311 and a second cooling passage 321. The first and second cooling passages 311 and 321 are connected to each other by a connection pipe 330 on the upper or lower ends of the sectors 310. Although it is not shown in the drawings, a coolant circulation device such as a circulation pump is connected to the first cooling passage and the second cooling passage so that coolant can circulate along the first and second cooling passages.
For example, coolant circulates through the sectors in such a way that coolant is drawn into the first cooling passage 311 by the circulation pump (not shown), is transferred to the second cooling passage 321 along the connection pipe 330, and then is returned from the second cooling passage 321 to the circulation pump. As such, the cooling operation is conducted in each pair of adjacent sectors.
The melter includes an even number of sectors such that a pair of sectors is the basic unit of the melter.
In detail, referring to
The cooling passage 411 or the cooling tube 420 is connected to at least one common coolant header (not shown). The cooling passage and the cooling tube are connected to a coolant circulation device (not shown) for circulation of coolant.
Although, in
As shown in
[Table 1] quantitatively shows a current distribution ratio (%) by models, which results from the analysis. It was understood that the sector structure of the present invention is higher than the conventional technique in a ratio of induction current applied to glass.
Therefore, the cold crucible induction melter according to the present invention can increase the operational efficiency compared to the conventional sector structure.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, the present invention is not limited to the embodiments or drawings.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/KR2011/007052 | 9/26/2011 | WO | 00 | 5/6/2013 |
