Abstract:
An electrolytic apparatus for molten salt disposed on an electrolytic cell to electrolyze an electrolytic bath consisting of the mixed molten salt. The apparatus including a first heat exchanging means to heat and/or cool an electrolytic cell body. The apparatus including a support member comprising one of a flange part and an upper lid. The apparatus including a cover member. The apparatus including an electric insulating material and a gas sealing material disposed between the support member and the cover member for simultaneous electric insulation and gas sealing.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based upon and claims the benefit of priority under 35 U.S.C. §120 from U.S. patent application Ser. No. 10/760,505, filed on Jan. 21, 2004, which claims the benefit of priority under 35 U.S.C. §119 (a)-(d) from prior Japanese Patent Application 2003-013778, filed on Jan. 22, 2003; the entire contents of each of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an electrolytic apparatus for molten salt, more particularly to an electrolytic apparatus for molten salt, which can be compact, with excellent sealing property. 
         [0004]    2. Description of the Related Art 
         [0005]    Fluorine gas is an indispensable basic gas in the semiconductor manufacturing field. Further, fluorine gas is used for the semiconductor manufacturing field independently, but nitrogen trifluoride gas (hereinafter referred to as NF 3  gas) is synthesized based on fluorine gas. The demand for cleaning gas and dry etching gas to be used in semiconductor industry is increasing rapidly. Also, neon fluoride gas (hereinafter referred to as NeF gas) and krypton fluoride gas (hereinafter referred to as KrF gas) or the like are excimer laser oscillator gases, which are used for the patterning process for producing a semiconductor integrated circuit. 
         [0006]    Fluorine gas and NF 3  gas which used for manufacturing semiconductors are required for high purity. Also, a required amount of fluorine gas, filled up in a gas cylinder, is taken out and used at the manufacturing site. Accordingly, the management of storage places for the gas cylinder, security of the gas, and purity maintenance is very important. 
         [0007]    Furthermore, as the demand of NF 3  gas is rapidly increasing, there are problems such as storage supply and the use of fluorides in view of global warming. Additionally fluorine gas is being used more widely in many applications. In view of these problems, fluorine gas generator on demand is preferable to treat the high pressure fluorine gas stuffed in the cylinder in for improvement of security and convenience of degree of freedom for gas supply. 
         [0008]    Conventionally, fluorine gas is generated by an electrolytic cell as shown in  FIG. 6 . For the material of the main part of the electrolytic cell  201 , nickel (hereinafter referred to as Ni), Monel, carbon steel or similar materials are generally used. A heater and/or a cooling device  214  is disposed surrounding the electrolytic cell body  201  to keep the temperature of the electrolytic bath  202  constant and to be capable of electrolysis. Also, the electrolytic cell body  201  is divided into an anode chamber  210  and a cathode chamber  211  by partition wall  209  made of Monel or the like. The fluorine gas is generated by electrolyzing the electrolytic bath  202 , in which an electric voltage is applied between the anode  203 , made of carbon or nickel disposed in the anode chamber  210 , and the cathode  204 , consisting of iron or nickel disposed in the cathode chamber  211 . 
         [0009]    However, as in the case of disposing the fluorine gas generator in the semiconductor manufacturing plants, there are many restrictions for installation conditions. Therefore, it is very important to make the gas generator compact. To make the electrolytic apparatus compact, it is necessary to consider rearrangement of the heat exchanger parts. 
         [0010]    Usually, the temperature of the electrolytic bath in the electrolytic cell is being kept constant by a heating apparatus such as heater or the like which is disposed around the electrolytic cell to control the electrolyzing condition by maintaining temperature of the electrolytic bath in the gas generator. Also, preventing the rapid temperature change in the electrolytic cell by using heat insulator disposed around the electrolytic cell (including heater) is necessary to improve energy efficiency and to prevent the burning of operators due to rapid temperature rise. Generally, asbestos, urethane or the like is used for heat insulator, the insulating performance is not only inadequate, but also there is a problem of working environment such as a scattering of the particles or the like which are formed of fibers or coarse particles. 
         [0011]    Also, according to conventional industrial electrolytic cell, sealing material, such as shape packing, is used for the gas generating parts in electrolytic cell for keeping the invasion of an atmospheric gas such as air or the like outside of the electrolytic cell and preventing the leakage of the gas such as fluorine or hydrogen from the electrolytic cell. However, the airtightness of the electrolytic cell may be inadequate, even if shaped packings are used. Also, in many electrolytic cells used today, electric insulation of connection between electrodes for electrolyzing and terminal is not enough. 
         [0012]    Accordingly, the purpose of the present invention is to provide an electrolytic apparatus for molten salt which can be compact. Also, the purpose of the present invention is to provide an excellent electrolytic apparatus for molten salt having an electric insulation, gas sealing and security against heat and generated gas. 
       SUMMARY OF THE INVENTION 
       [0013]    The purpose of the present invention is to provide a compact electrolytic cell body, heat insulation structure such as heat exchanger parts, improvement of electric insulation, gas leakage and work safety. 
         [0014]    Namely, the present invention relates to an electrolytic apparatus for molten salt having an electrolytic cell to electrolyze an electrolytic bath consisting of a mixed molten salt comprising a first heat exchanging means to heat and/or cool the electrolytic cell body, and an outer frame disposed outside of the first heat exchanging means with space and to seal the first exchanging means, and a heat insulating zone capable of decompression or vacuum formed inside the outer frame. According to the present invention, since the electrolytic cell has a decompression or vacuum heat insulation structure, coefficient of thermal conductivity can be extremely low compared with the heat insulator such as asbestos or urethane. As the result, thickness of the heat insulating zone can be thin. Therefore, electrolytic cell can be compact and working safety is improved. Further, the heat energy loss of the electrolytic cell body can be decreased. Also, there are no particles. In addition, in this invention, heat exchanging means for heating and/or cooling the both of the electrolytic cell body is provided. As a result, the efficiency of heat exchanging can be improved by combination of heating and cooling of electrolytic cell with first heat exchanging means. Further, target pressure by decompression or vacuum, approximately 10 kPa-1000 Pa is preferable. When the pressure of heat insulating zone is less than 10 kPa, the thermal conductivity by gases cannot be lowered, which decreases the efficiency of heat insulation. Also, to make the pressure of heat insulating zone less than 100 Pa, another large equipment is required, resulting in high cost. Accordingly, to decompress the pressure of heat insulating zone, 10 kPa to 1 kPa is preferable. 
         [0015]    Also, the present invention relates to the electrolytic apparatus for molten salt, wherein the electrolytic apparatus may further comprise a second heat exchanging means to heat the electrolytic cell body. The second heat exchanging means according to the present invention is provided in case it is difficult to heat only with the first exchanging means, or in case that further precise temperature controlling is required, like heating, cooling or to capable to change, such as heating parts disposed on the bottom of electrolytic cell body, a heater disposed on the pipe for supplying the HF can be shown in for example. 
         [0016]    Further, the present invention relates to the electrolytic apparatus having the electrolytic cell body for electrolyzing the electrolytic bath consisting of the mixed molten salt, the electrolytic apparatus comprises the first heat exchanging means to heat and/or cool the electrolytic cell body, and a part which is required for electrical insulation and gas insulation simultaneously. An electrolytic insulating material described in the present invention is defined as a material such as volume specific resistance value which is not less than 10 6  Ω·m measured by JIS K 6911. Also, as an electric insulating material, having a corrosion resistance characteristic against generated fluorine gas is preferable, fluoride rubbers, fluorocarbon resin like polytetrafluoroethylene (hereinafter referred to as PTFE), PFA (tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer) are shown as examples. By inserting the electric insulating material between electrolytic cell body and upper lid, electrical insulation is improved. Furthermore a material should have an airtightness and an elasticity is more preferable, such as fluorinated rubber, for example. The gas sealing material should preferably be disposed where fluorine gas, HF gas or the like are likely to leak. Also, the gas sealing property is defined as a degree of pressure change after temperature compensation is within ±1%, when the gas pressure of 1.1 times or more than usual operating pressure within nitrogen gas atmosphere and keeps for 24 hours in the electrolytic apparatus. By this construction, invasion of outside gas in the electrolytic cell is controlled, which improves impurity of the generated gas. Also, by electrolyzing the electrolytic cell, the generated gas cannot easily leak out from the electrolytic apparatus, as the result, an improvement of working environment and security can be improved. 
         [0017]    Furthermore, the present invention relates to an electrolytic apparatus for molten salt comprising an electrolytic cell to electrolyze the electrolytic bath consisting of a mixed molten salt, wherein the electrolytic apparatus having the electric insulating material and the gas sealing material, in case of the electric insulating property and gas sealing property are required in the electrolytic cell simultaneously. By this construction, the electric insulating effect, airtightness, the purity of the generated gas and security can further be improved. 
         [0018]    Also, the present invention relates to the electrolytic apparatus for molten salt comprising a flow line to flow a heat exchanging medium in the first heat exchanging means surrounding the electrolytic cell body. By this construction, by circulating the heat exchanging medium, heating and/or cooling the electrolytic cell is easy and effective. As a result, melting of salt used as the raw material of electrolytic bath and removal of generating heat by electrolyzing can be carried out effectively. 
         [0019]    Further, the present invention relates to the electrolytic apparatus for molten salt, wherein the heat exchanging medium is a fluid consisted of high electric insulating material. By this construction, short-circuiting from heat medium can be prevented, when the electrolytic cell body becomes cathode. For the electric insulating material, liquids such as water (pure water or distilled water) fluorinated oil, silicone oil, or gases such as Ar gas or He gas may be used, but is not limited to these materials. In addition, to consider easy access, using water is preferable. Using pure water is more preferable. 
         [0020]    Also, the present invention relates to the electrolytic apparatus for molten salt, wherein the electrolytic cell is disposed in the box whose upper part is open. The purpose of adopting such box is to separate the electrolytic cell from outside of the electrolytic cell. The box material is not limited, but it is necessary to have the corrosion resistance and heat resistance against the generated gas by generating and electrolytic bath component, metal such as a stainless, PTFE, is shown as an example. Also, in order to prevent the leak of electrolyte, disposing the box at the bottom of the electrolytic cell is preferable. 
         [0021]    Further, the present invention relates to the electrolytic apparatus, wherein a mixed molten salt comprise a hydrogen fluoride. 
         [0022]    According to the present invention, as the effect of insulation is improved by forming the heat insulating zone, it is possible to make the apparatus more compact than conventional electrolytic apparatuses. Accordingly, the heat discharge to the outside can be dropped, and the electrolytic cell is heated effectively, as the result, the waste of energy can be minimized by heat exchanging means. Also, as the heat insulating zone is decompressing, scattering of the particles, which is one of the deteriorating factors, can be prevented in the semiconductor manufacturing process. Further, by means of consideration, gas sealing material, electric insulating material and gas sealing property are improved, and the high purity gas can be obtained. Furthermore, the gas leakage can be prevented. As a result, it is possible to use the apparatus at the semiconductor manufacturing site. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  is an outer elevational, partially cross-sectional view of the principal part of the fluorine gas generator relating to the present invention. 
           [0024]      FIG. 2  is a perspective view of the electrolytic cell showing the internal structure of the outer frame, according to the present invention. 
           [0025]      FIG. 3  is a cross sectional view of the electrolytic cell body according to the present invention. 
           [0026]      FIG. 4  is an expanded cross sectional view of part A shown in  FIG. 3 . 
           [0027]      FIG. 5  is an expanded cross sectional view of part B shown in  FIG. 3 . 
           [0028]      FIG. 6  is a schematic cross sectional view of the fluorine gas generator which was being used conventionally. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]    Hereinafter, based on the drawings  1 - 5 , preferred embodiments of the present invention relating to the fluorine gas generator are described more in detail. 
         [0030]    The construction of fluorine gas generator (an electrolytic apparatus for molten salt) is shown in  FIG. 1. 1  is an electrolytic cell consisting of electrolytic cell body  1   a  and upper lid  17 , and  2  is an electrolytic bath consisting of mixed molten salt made of KF-2HF type,  3  is an anode chamber,  4  is a cathode chamber,  5  is an anode,  6  is a cathode.  22  is an outlet port for C-1 generated fluorine gas in anode chamber  3 .  11  is a thermometer to measure the temperature in the electrolytic bath  2 ,  13  is a heat exchanging means of electrolytic cell  1 ,  12  is an apparatus for warm water heating to supply the warm water for heat exchanging means  13 .  51  is a warm water jacket disposed on the side of electrolytic cell  1 , which constructs heat exchanging means,  52  is a heating parts (secondary heat exchanging means), which constructs heat exchanging means  13  and disposed outside of the bottom of electrolytic cell  1 . 
         [0031]    The electrolytic cell  1  is made of a metal such as Ni, Monel, pure iron or stainless steel. Inside of the electrolytic cell  1 , separator  16  made of Ni or Monel divides into the anode chamber  3  and the cathode chamber  4  in the center of the electrolytic cell  1 . An anode  5  is disposed in the anode chamber  3 , and a cathode  6  is disposed in the cathode chamber  4 . For the anode  5 , low polarized carbon electrode is preferable. Also, cathode  6  preferably consists of Ni machined into predetermined shape. 
         [0032]    A flange part  1   b  connected to a circumferential edge of the upper lid  17  is formed on the upper circumference of the electrolytic cell body  1   a . A concave groove  1   c  shown in  FIG. 2  and  FIG. 3  surrounds the plane of the flange part  1   b  side, which is connected to upper lid  17 . 
         [0033]    The upper lid  17  shown in  FIG. 3  and  FIG. 4  is placed and fixed to the screw part  31  and to the flange part  1   b  by bolt  30 , and a electric insulating bushing  32  is placed between bolt  30  and upper lid  17 . Since the upper lid  17  and electrolytic cell body  1   a  are connected by bolt  30  at a squeezing strength of 5-30 N·m with the electric insulating material  32 , placed there between (the upper lid  17 ) is insulated electrically without hurting an insulation resin. Also, electric insulating material  9  and gas sealing material  10  are placed between flange part  1   b  and circumferential edge of upper lid  17 . As this gas sealing material  10 , O ring made of fluorinated rubber having a corrosion resistance against the fluorine gas is used for and disposed in the groove  1   c  of flange  1   b . In addition, on the plane of upper lid  17  of flange part  1   b , plurality of screw parts  31  are formed at a predetermined interval and upper lid  17  is fixed to flange part  1   b  with same number of bolts  30 . 
         [0034]    Also, electric insulating material  9  (wherein right and left both sides in  FIG. 3 ), which is disposed surrounding the inside and the outside of gas sealing material  10 , and is disposed along the interstice between flange  1   b  and upper lid  17 . For this electric insulating material  9 , polytetrafluoroethylene (PTFE) or the like can be used. 
         [0035]    By placing the electric insulating material  9  and gas sealing material  10  between upper lid  17  and electrolytic cell body  1   a , upper lid  17  can be easily removed from the electrolytic cell body  1   a . Also, by placing the gas sealing material  10  between electrolytic cell body  1   a  and upper lid  17 , fluorine gas, hydrogen gas and HF gas or the like cannot leak out of the electrolytic cell  1 , and a gas outside cannot invade into the electrolytic cell  1 . Further, the short-circuiting between upper lid  17  and electrolytic cell body  1   a  is prevented by electrical insulation such as an electric insulating material  9 . 
         [0036]    As shown in  FIG. 1 , an outlet port  22  for generated fluorine gas from anode chamber  3 , and an outlet port for generated hydrogen gas from cathode chamber  4 , and HF introducing port  25  of HF feed line  24  to feed HF, and pressure gauges  7 ,  8  to detect the pressure inside of the anode chamber  3  and the cathode chamber  4  respectively, are disposed to the upper lid  17  on the electrolytic cell  1 . 
         [0037]    Also, as shown in  FIG. 5 , almost at the center of the upper lid  17 , an opening part  35  is formed to insert the anode  5  into the electrolytic cell body  1   a , and a cover body  36  is disposed to cover the opening part  35 . A connecting rod  37  to which anode  5  is attached is provided perpendicularly to this cover  36 . L-shaped cross section attachment  38  is provided at the lower end of connecting rod  37 , to which upper part of anode  5  is attached by connecting bolt  39  penetrating through holes (not shown) of the upper part of the anode  5 . 
         [0038]    The above-mentioned electric insulating material  9   a  and O ring  10   a , analogous to electric insulating material  9  and gas sealing material  10 , are disposed between this cover body  36  and the upper lid  17 . Thus, by placing the electric insulating material  9   a  and O ring  10   a  between cover body  36  and upper lid  17 , gas such as fluorine gas and hydrogen fluoride gas in the electrolytic cell  1  do not leak out, and permeation of the air into the electrolytic cell  1  can be prevented. Also, the cover body  36 , which surface is being applied by an insulation paint, and electrical connecting part (terminal stand), which is covered with the resin material of electric insulation, prevents short-circuiting with outside. 
         [0039]    The gas outlet ports  22 ,  23  disposed on the upper lid  17  have tubes which are formed of the material having the corrosion resistance against the fluorine gas, such as stainless steel or the like. Also, the HF feed line  24  is covered with a thermo controlling heater (secondary heat exchanging means)  24   a  to prevent the HF from liquefaction. 
         [0040]    The heat exchanging means  13  shown in  FIG. 2  is constructed with the warm water jacket  51 , which surround the electrolytic cell  1 . The heating parts (secondary heat exchanging means)  52  are disposed on the bottom of electrolytic cell  1 . 
         [0041]    The warm water jacket  51  comprises a warm water pipe (first heat exchanging means)  53  which has a stream line  53   a  (referred to as  FIG. 3 ) which can flow a heat medium, and a vacuum insulating zone  55  formed inside of an outer frame  54  having a sealed warm water pipe  53 , and surrounding with space furthermore to the warm water pipe  53 . 
         [0042]    The warm water pipe  53  is disposed surrounding the side of electrolytic cell  1  horizontally and at the fixed interval, and connects each other at the connection part (not shown) and connected. Also, as the material of the warm pipe  53 , material having an excellent thermal conductivity like copper is preferable, but it is not limited, metal pipe, such as iron, stainless steel, aluminum or the like can be applied, for example. 
         [0043]    As shown in  FIG. 2 , the shape of warm water pipe  53  is preferably rectangular. When the shape is a rectangular cross-section, contact area with the side of electrolytic cell  1  can be made larger. As a result, the thermal energy of thermal medium can be conducted for the electrolytic cell  1  effectively, but the shape is not limited. A circle pipe, a triangular pipe, a semicircular pipe by cutting half with the surface which goes through the main axis in the circle pipe can be applied, for example. Namely, if the pipe is semi-circular, by disposing the semi-circular pipe side of the electrolytic cell  1 , the aisle, which includes the surrounding of the electrolytic cell  1  can be formed between semi-circular pipe and surrounding of the electrolytic cell  1 . The heat medium hereafter mentioned flows in this aisle and serves as the warm water pipe  53 . 
         [0044]    Also, the warm water pipe  53  is equipped along the longitudinal direction generally by welding having a welding part side of the electrolytic cell  1 . The sealing material having a high thermal conductivity is placed between two welding parts along with the longitudinal direction of the warm water pipe  53 . Thus, by placing the sealing material, the contact area between warm water pipe  53  and the side of electrolytic cell  1  can be made larger and the efficiency of thermal conductivity from the warm water pipe  53  can be improved. 
         [0045]    Further, the semi-circular pipe can be also attached surrounding the electrolytic cell  1  along the longitudinal direction regularly by welding. By filling up the sealing material between two welding parts, the leakage of the heat medium from the aisle can be prevented and the heat energy of the heat medium transmitted to the semicircle pipe can be transmitted to the electrolytic cell  1  by placing the sealing material like said warm water pipe  53 . 
         [0046]    Also, heated heat medium with the warm water heating apparatus  12  shown in  FIG. 2  is being circulated in the aisle of warm water pipe  53 . This heat medium consists of pure water, and the warm water  56  heated at the warm water by heating apparatus is being circulated in the arrowed direction shown in  FIG. 2 . 
         [0047]    Since the heat medium is being circuited in the aisle  53   a  of the warm water pipe  53  of the first heat exchanging means, the first heat exchanging means can be cleaned and sealed. Also, by using the pure water for heat medium, electrolytic cell body  1   a  and the heat medium are insulated electrically, and electrical short-circuiting between electrolytic cell body  1   a  and heat medium can be prevented. Since the pure water does not contain the impurity and almost does not conduct electricity, the electric current is not conducted from the warm water apparatus  12  by using the pure water. Therefore, the generation of the electrical leakage between electrolytic cell body  1   a  and heat medium such as pure water can be mostly prevented. 
         [0048]    In addition, the pipe from the warm water heating apparatus  12  connecting with warm water pipe  53  can be insulated electrically by using the pipe which is an insulating material itself or connection with the insulating material between the two pipes. Also, in the preferred embodiment, polytetrafluoroetylene (PTFE) hose is adopted for the pipe. Further, the electric insulation resistance increases as the length of tube is getting longer. Therefore, the length between warm water apparatus  12  and electrolytic cell  1  should be 10 centimeters or more is preferably, 30 centimeters. 
         [0049]    Further, the check valve is disposed in the outer frame  54  (not shown), vacuum insulating zone  55  is formed to be decompression or vacuum insulating layer by vacuuming the air with decompression machine or the like shown in  FIG. 1  from the vacuum insulating zone  55  which is formed between outer frame  54  and warm water pipe  53 . As a result, the heat generated by flowing the heat medium to the aisle  53   a  in the warm water pipe  53  almost cannot be emitted to the outside, and the electrolytic cell  1  is heated effectively by warm water pipe  53  contacted with electrolytic cell  1 . Since the vacuum insulation zone  55  is decompression or vacuum, the particles from the insulating layer to be one of the factors is not generated in the process for manufacturing the semiconductor. Therefore, it is possible to use the generator on-site in the process for manufacturing the semiconductor. Also, as the warm water pipe  53  is being surrounded by outer frame  54 , the temperature of the atmosphere surrounding the electrolytic cell  1  is not only being raised, but also kept clean. Therefore, as it is possible to prevent the workers from burning or the like, safety is improved. 
         [0050]    A heating part  52  which is consisted of a rubber insulating layer  52   a  disposed on the bottom of electrolytic cell body  1 , and a heating layer  52   b  which has a nichrome wire disposed all faces inside, and laminated and shaped plate like. The bottom of the electrolytic cell  1  is heated by the heating part  52 , which is supplied with electric power from an electric power source (not shown) and via insulating layer  52   a . Accordingly, a heat emission from the bottom of electrolytic cell  1  is prevented by heat parts  52 . Also, as the shape of the heat part  52  is plate like, the bottom surface of electrolytic cell  1  is placed stably. 
         [0051]    Further, the warm water heating apparatus  12  which supplies the warm water heating the pure water to the warm jacket  51  comprises, a heat medium heating means (not shown) in the warm water jacket  51  and thermo controlling apparatus (not shown) which controls the heat medium heating means. Furthermore, warm water heating apparatus  12 , which is connected with thermometer  11  which measures temperature of the electrolytic bath  2  in the electrolytic cell  1  warm water jacket  51  which heats the electrolytic bath  2  in the electrolytic cell  1 , and provides warm water  56  into the warm water jacket  51  to maintain the temperature of the electrolytic cell  1  based on the thermal information of thermometer  11 . Further, by providing the pressure controlling function to the warm water heating apparatus  12 , the tube can be connected with warm water heating apparatus  12 , warm water pipe  53  and other tubes in the sealed condition. By heating the warm water, from the warm water pipe  53  sealed and connected to warm water heating apparatus, in the case of the pressure rising in the tube (warm water pipe), this pressure is eased by warm water heating apparatus  12 . Also, in the case of cooling the warm water, the pressure of warm water pipe is dropped, in this case, the pressure is compensated by warm water heating apparatus  12 . By providing the function like this, without decreasing warm water due to the vaporization of warm water at the time of heating, and the permeation of the air or the like can be prevented by decompressing in the tube at the time of the cooling. By this construction, it is not necessary to compensate with warm water or the like, the contamination from the substance outside can be prevented. As a result, the corrosion of the warm water pipe  53  or the like can be prevented. 
         [0052]    Thus, as the warm water jacket  51  which has the decompression or vacuum thermally heat insulating structure, the coefficient of thermal conductivity of the insulation zone is extremely minimized than insulation zone which is made of the material such as asbestos, urethane or the like, the thickness of the insulating zone  55  itself can be thinned. Therefore, the electrolytic apparatus can be compacted, the security is improved, and a loss of heating energy can be reduced. Also, generating of the particles from insulating material is prevented. 
         [0053]    The electrolytic cell  1  described above is contained in the box  60  with upper open shown in  FIG. 1 . This box  60  has a bottom plate  61  which is a slightly larger rectangle shape than the bottom of electrolytic cell  1 , and four side plates  62  which are slightly larger rectangle shapes than the side of electrolytic cell  1 , and the connection part between bottom plate  61  and  4  side plates  62  sealing material is being placed from inside. Since the sealing material is provided in this connection part, the water leakage from the box  60  can be prevented. 
         [0054]    The material or the shape of the box  60  is not limited specifically, but it is necessary to contain the electrolytic cell body  1   a  and to prevent the spread warm water jacket  51  or the connection part between the pipe from warm water heat apparatus  12  and warm water jacket  51  from the leakage of warm water. By this construction, the leakage to the outside of the heat medium such as the pure water heated (warm water  56 ) or the like from warm water pipe  53  can be prevented. 
         [0055]    Next, the preferable embodiment of the operation for the fluorine gas generator. By applying the voltage between the anode  5  and the cathode  6  in the electrolytic cell  1 , the fluorine gas is generated from anode  5 , and hydrogen gas is generated from cathode  6 , under the normal conditions. The fluorine gas generated from anode  5  is supplied to the line from the fluorine gas outlet port  22  of the upper part of the anode chamber. Also, the hydrogen gas generated from cathode  6  is supplied to the line from the hydrogen gas outlet port  22  of the upper part of the anode chamber. 
         [0056]    And, as the decreasing of the electrolytic bath  2  by means of continuous electrolyzing, liquid surface level detective means (not shown) is operated. By this linkage, HF is supplied to the electrolytic bath  2  from HF supply line  24  via HF outlet port  25 . Thus, as the HF decreasing such as the material for electrolyzing depends on by electrolyzing between the anode  5  and the cathode  6  in the electrolytic bath  2 , HF is introduced to the electrolytic bath  2  continuously and HF concentration in the Electrolytic bath  2  is being kept at the optimal condition. As the result, the condition of electrolyzing is always stabilized. 
         [0057]    Also, to carry out the electrolysis with electrolytic bath  2  efficiently, electrolytic bath  2  is heated to an optimal temperature by heat exchanging means  3  via electrolytic cell  1 . The electrolytic bath  2  is kept at the optimal temperature by the thermometer  11  to monitor the temperature in the electrolytic bath  2 , and warm water heating apparatus  12  to heat the pure water supplying to the warm water jacket  51 , and a plate like heating part. 
         [0058]    Also, as the warm water jacket  51  which has the decompression or vacuum zone  55  due to the outlet  54 , the heat energy generated can be connected (heated) efficiently, via the surrounding outside of the electrolytic cell  1  and temperature rise of the warm water jacket surrounding outside can be prevented. Accordingly, the aggravation of the atmosphere surrounding of the heat exchanging means  13  is not only prevented, but also the energy loss of the heat exchanging means  13  can be prevented, and the electrolytic bath is kept at an optimal temperature. As a result, electrolysis can be carried out by anode  5  and cathode  6  efficiently, and fluorine gas can be generated stably. 
         [0059]    In addition, although the electrolytic apparatus for molten salt accordance with the present invention is mainly explained fluorine gas generator to generate the fluorine gas by electrolyzing, the present invention is not limited to the fluorine gas generator. Also, the warm water heating apparatus  12  to supply the warm water  56  to the warm water jacket  56  is not only for heating, but cooling for the medium is also possible. By applying the warm water heating apparatus, the temperature adjustment of the electrolytic bath  2  in the electrolytic cell  1  can be carried out promptly.