NO140167B - PROCEDURE FOR CARRYING OUT HEAT REQUIRED CHEMICAL AND / OR PHYSICAL PROCESSES - Google Patents

Description

The present invention relates to a method for carrying out heat-demanding chemical and/or physical processes in a reactor space containing essentially the material that is included in the process, in the form of a layer, and where at least part of the energy required for the process is formed on electro-inductive way in the layer itself using at least one induction coil placed outside the reactor space, through which an alternating current is fed.

The invention primarily relates to a method for carrying out heat-demanding processes in a coke layer. Coke which is produced from hard coal of varying age or from lignite or coal, which is produced by pyrolysis of other organic material, is used within the technique for carrying out various operations, during which the carbonaceous material is oxidized and/or reacted with or dissolved in another component. In the description, the term coke is used for all carbonaceous material, produced by pyrolysis of organic materials.

The heat required for the above-mentioned processes can

is supplied to the reactor space in different ways. For example, the coke and the other reactants can be preheated, heat can be developed in the reactor space by partial combustion of the coke, or heat can be supplied through the walls of the reactor space.

Other methods are based on direct heating of the coke or the reaction mixture electrically. The latter method often involves advantages compared to the other mentioned methods, despite the relatively high price per energy unit for electrical energy. Among these advantages can be mentioned less volume-requiring equipment both for the process itself and for taking care of any exhaust gases, great flexibility with regard to process design, greater freedom with regard to the choice of raw materials with varying properties, high yield with regard to the added energy, as well as wide range with regard to economic management of the production map ra tour.

A common way of developing electrical energy is to supply electrical current through electrodes to heat the reaction mass by resistance heating or with an electric arc.

Another way is to induce electric currents in the reaction mass by placing an alternating electromagnetic field over it, so-called inductive heating. This method has been proposed in connection with the production of coke from hard coal. Due to the relatively high electrical resistance, in such cases it has been assumed that it has been necessary either to use very high frequencies in the alternating field, or to let the material subjected to heat treatment form a secondary winding in a transformer-like device.

Utilization of high frequencies, however, entails certain limitations of a technical and economic nature. The transformer method, on the other hand, where coal or other material is introduced into a chute to form a closed current circuit, will be avoided for practical reasons in many cases.

It has now surprisingly turned out that it is possible to achieve very good technical and economic results. favorable results when carrying out processes of the above type, if, according to the present invention, a layer with a resistivity (?) within the range of 10 and 10 ohm m and an alternating current with a low frequency which is at most ten times the mains frequency which is 50 Hz is used, preferably no more than five times the mains frequency, and one maintains a ratio between the smallest transverse dimension (d) of the layer area and the inductive field's penetration depth (<f) in the range 0.2 - 2.5, which ratio is determined by the equation j = k (0.54 - 0.35.10log<P), where k is a number in the range 1.1 - 1.5, preferably approx. 1.2. The term penetration depth used above has the following meaning:

where co is the angular frequency of the electromagnetic field, measured in radians/sec, [ i is the permeability (for non-magnetic material approx.

4ff • lo -7 ) and 9 is the resistivity of the layer, measured in ohm m. The transverse dimension d of the layer is measured in m in this connection. According to the invention, it has thus been shown to be possible to carry out processes of the type in question using low frequencies below which the cross-layer dimensions must be covered to a relatively small extent compared to the dimensions that are necessary for known low-frequency heating of materials with low resistance. As an example, it can be mentioned that when inductively heating a coke layer with a resistivity of 10 ohms

with an alternating current frequency of 100 Hz, an induction coil with a diameter of only 7.5 m was found to be suitable with a coil height to diameter ratio of 0.6.

According to the invention, it has been shown that very high amounts of energy can be developed in a coke layer already with suitable strength of the electromagnetic field. At the same time, the losses due to the inductive heating of the induction coil, if this consists of copper, have been found to constitute only a few percent of the added energy. In the example given above, at a field strength of only 50 kA/m, approx. 30 MW in the coke layer, whereby the loss in the copper coil at the same time amounted to only 600 kW, i.e. 2% of the supplied energy.

By utilizing the extended adaptation of the inductive heating process which can be used when heating lumpy material in layers with a resistivity in the range 10 - 10 _4 ohm m, éS:: thus the high resistivity previously regarded as an obstacle has now been converted into a advantage.

According to one embodiment of the invention, an alternating current with a mains frequency is used in those cases where it is desired to take energy from the electrical grid, whereby both installation and operating costs are kept low. Should it be necessary to use a frequency increase, the appropriate induction coil is allowed to flow through an alternating current whose frequency is not higher than 10 times the mains frequency and which preferably constitutes an integer multiple of the mains frequency, preferably not more than 5 times the mains frequency. Within the specified areas, power of the desired frequency can be obtained at low costs and with a high degree of efficiency by using constructively simple and cheap engine- or turbine-driven generators, alternatively, for example, frequency multipliers or thyristor-controlled current rectifiers can be used in cases where not too large power requirement is required.

In summary, it can be said that the method of supplying inductive energy with low-frequency or relatively low-frequency strbm to a layer with a resistivity in the range IO - 10~<4> ohm m achieves the following advantages compared to the previously known technique: 1. Reactor units with significant dimensions can be carried out with very high power development per volume unit and thus high productivity. 2. The field's penetration depth is large in relation to the reactor the cross-section, whereby a more even energy development is achieved over the cross-section.

Previously unachieved amounts of energy can be developed inductively

manner.

4. The electrical efficiency is improved to the greatest extent.

5. Devices for generating current with the desired low frequency become simpler and cheaper and have a higher electrical efficiency; often the network frequency can be utilized.

In the method according to the invention, not all the necessary heat needs to be supplied electro-inductively. Thus, it is within the scope of the invention to supply part of the heat required for the process to the reactor space by burning combustible components therein.

The invention can be advantageously adapted in connection with the coking of coal, which during the coking is preferably at least partially fed continuously through the reactor space, whereby the inductively obtained heat is developed in part of the material being coked, which is essentially completely freed from gasifiable components. As the inductive heat is developed directly in the material that is subjected to coking, a rapid coking process is obtained, so that significant amounts of coal can be coked per unit of time with a relatively small apparatus.

Appropriately, the formed coke is discharged from the reactor room via a liquid lock, whereby the coke is disconnected, whereby many sanitary disadvantages are avoided. In order to improve the quality of the coked material, at least part of the coking gas and/or an additional reactor chamber can

The added hydrocarbon is made to pass through a finely divided, coked or essentially coked material in the reactor space.

ale, in which a for cracking of coking gas is maintained

respectively the hydrocarbon required temperature, whereby a substantial increase in the strength of the coke can be achieved by a strong

increased carbon deposition on the coked material. In this way, first-class coke can be produced, such as metallurgical coke,

without secondary raw materials.

Part of the heat required for coking can be supplied to the reactor chamber by direct combustion of combustible components

is therein, preferably without contact with the coked material. The combustible components can consist of all or part of the gases formed during coking, but also all or part of components that are supplied to the reactor space from outside, for example a hydrocarbon. Appropriately, the heat generated by such direct combustion in the reactor space can be utilized for preheating and partial coking of the coal supplied to the reactor space. The heat developed during the combustion of the combustible components, which is not absorbed by the material

easily in the reactor space, can be taken care of in the following in a radiation part which is placed in connection with a steam boiler arranged in the reactor. Alternatively, at least part of the heat content of the gases formed in the coking reactor can be utilized for the production of, for example, steam or electrical energy. When electrical energy is produced, in the present and other embodiments of the invention, this can advantageously be done with the utilization of steam or gas

bin, preferably a hot air turbine. The generated electrical energy can be utilized for the process's energy consumption, and the electrical energy

gi can thereby be produced in the form of an alternating current with a frequency used for the process used. Likewise, the still warm air leaving a hot-air turbine can be used for the above-mentioned combustion in the reactor space, whereby a high thermal efficiency is achieved in the process.

The invention can also be advantageously adapted in connection with the reduction and/or gasification of a gaseous medium, for example for the production of reducing or protective gases, whereby the gaseous medium, which can for example be made up of water-steam, circulating gases from reduction processes, with the addition of of hydrocarbon etc. is made to pass through the ad inductively heated coke layer in an essentially continuous manner during successive consumption of this. In the same way as in the case of coking, with this manufacturing method, very high capacities can be achieved in a reactor with small dimensions, as a result of the relatively evenly distributed heat generation in the entire coke layer by inductive heating. Appropriately, the layer temperature can be kept so high that the slag formed by coke consumption in the layer is obtained as a melt at the bottom of the reactor chamber, where the slag melt is either interrupted or continuously drained from the reactor chamber. In this way, the removal of residues from the reactor space resulting from coke consumption is simplified. In order to maintain uniform conditions in the reactor space, it is appropriate that the coke consumed in the coke bed is essentially continuously replaced. The coke to replace the spent coke in the bed can be produced in the reactor room by supplying coal and coking this in the bed, whereby it is possible to build up the bed from a cheap raw material, and the quality of the coke formed can be improved on it with reference to coking of coal in the described manner whereby the hydrocarbons released during the coking, respectively those added to the furnace room, are simultaneously utilized in the process. To improve the heat economy, the gaseous medium, which is to be reduced and/or gasified, can be preheated by direct heat exchange with the reduced and/or gasified gas. Likewise, part of the heat required for coking and the rest of the process can be supplied to the reactor chamber by direct combustion of combustible components therein, respectively the heat developed by combustion of the combustible components, which is not absorbed by the material or the gases in the reactor chamber, can be taken care of in or outside the reactor, in the manner described with reference to the coking of coal. The combustion in the reactor space is carried out on the side of the coke bed from which the gaseous medium to be reduced and/or gasified is introduced into the coke bed. Particularly in such cases, it is appropriate from a gas-lining point of view and a construction point of view to feed the aforementioned gaseous medium down through the coke present in the reactor space. The physical heat content of the gases leaving the reactor can be suitably taken care of by heat exchange between these gases and the gases supplied to the reactor.

Another area where the present invention can be advantageously used is in the reduction and possibly subsequent carbonization or gasification of solid, metal oxide-containing, especially iron oxide- or calcium oxide-containing materials. Thereby, the material is supplied to the coke layer present in the reactor, in which the induction current is generated, whereby at least in the coke layer such a temperature is maintained that the metal oxide-containing material during reduction and sintering, as well as possible carbonization or gasification of this, is fed through the coke layer during successive consumption of this, whereby the formed slag and metal or metal carbide melt is continuously or intermittently drained from the reactor space. In this way, low-quality coke can be used without disadvantages, and it is possible to maintain a high and uniform temperature throughout the coke layer, so that an excellent production capacity is achieved compared to previously known reduction and smelting equipment. The method can be used with particular advantage in the final reduction of pre-reduced iron oxide material, such as iron oxide material reduced to at least FeO. In order to more effectively utilize the reducing power of the reducing gases formed by reduction in the coke layer, possibly also for reducing gases formed in the coke layer by introducing a liquid reducing agent, the metal oxide-containing material can be fed into the reactor space in such a finely divided form that at least during the initial phase of the reduction of this is kept fluidized by the gases formed, rising from the layer. The method is thus very suitable for the reduction of, for example, such fine-grained metal oxide material as silica fumes. The solid, metal oxide-containing material can advantageously be fed into the reactor space in a warm or preheated state.

Due to the difference in specific gravity of the metal or metal carbide melt and the slag melt, of which the latter melt may also be supplied with suitable refining or fluxing agent, the metal or metal carbide melt passes through the slag melt and collects in a zone below it. The metal or metal carbide melt and the slag melt are advantageously drained separately from the reactor. Particularly if the slag melt has a refining effect, it is advantageous to retain a layer of molten slag under the coke layer, whereby part of the heat required for the process can be developed inductively in the slag melt as well.

The coke consumed in the coke layer is advantageously replaced essentially continuously, which can be done by adding coal to, and coking this, in the furnace room. Otherwise, the coal can be preheated, and the coking process initiated, by combustible components being burned in the reactor space, whereby the heat of the combustion gases by radiation and convection is brought to act directly on the coal. The combustible gases can be made up of hydrocarbons that are supplied to the reactor room, either in the room above the batch or in the batch itself. For example, the hydrocarbon can be brought into contact with the coke and/or the coal that is coked, as this material is kept at least at such a temperature that the hydrocarbon is cracked and causes carbon precipitation on the coke. The heat developed by burning the combustible components, which is not taken up by the material and gases in the reactor space, can, as described above with reference to the coking of coal, be taken care of inside or outside the reactor.

The method according to the invention can also be adapted in connection with the melting of piece or particulate, fully or partially metallic material, for example pre-reduced metal oxides, such as sponge iron or metal scrap, such as iron waste, in particular low-grade metal waste 11, such as metal shavings and the like, whereby the said material together with a reducing agent to replace the spent coke is fed to the reactor, in which the material is melted down electro-inductively, and that the molten material passes through the also inductively heated coke layer during a possible final reduction of oxidized particles of the material and where, if necessary, the molten metal is carbonized during successive consumption of the coke layer, whereby the molten metal and slag formed are obtained in a zone below the coke layer, from which metal and slag are continuously or intermittently drained from the reactor space.

If a cheap heat source is available, the solid metallic or essentially metallic material can be preheated for introduction into the reactor space, whereby this material can also be introduced together with the material to form a slag for refining the metal alloy formed by melting. It is thereby possible to maintain a layer of molten slag under the coke layer, whereby heat can also be developed inductively in the slag melt. The coke consumed in the coke bed is preferably replaced continuously, whereby replacement coke can be formed by adding coal to, and coking this, in the reactor space, in the manner described above. Hydrocarbons can also be supplied to the reactor space partly as fuel for the formation of

part of the heat required for the process, and partly to increase the quality of the coke that is formed from the coal, as explained above

for. When burning combustible components in the reactor space, heat that is not taken up by the material in the reactor space can be taken care of in a radiation part arranged in the reactor space which is connected to a steam boiler arranged to the reactor, and at least part of the heat content

the gases formed in the reactor space can be used for the production of electrical energy or steam.

The invention can advantageously also be adapted in connection with the treatment of metal oxide melts. Thus, it can advantageously adapt

is seen in connection with the extraction of at least one metal, such as iron and silicon, from one of the aforementioned metals which are found in oxide-bound form in the smelter, for example in a slag, whereby the smelter is supplied with coke

layer, and the residence time for the smelting as well as the temperature in the coke layer are set so that the aforementioned oxide-bound metal is reduced by a simultaneous combustion of the coke layer and is obtained in molten form in a zone that lies below the coke layer, from which this as well as newly formed and possibly remaining slag is continuously or interruptedly drained from the reactor room. The coke layer thereby forms a very large heat contact

surface of a reducing nature for the metal oxide melt, so that

the larger the capacity of the reactor. The metal melt and the slag melt can be tapped separately from the reactor. Especially if the slag melt has a refining effect, for example obtained by adding a suitable refining agent1, it is advantageous to retain a layer of melt

dense slag under the coke layer, whereby part of it for the smelting process

the necessary heat can also be generated inductively in the slag melt.

The coke consumed in the coke layer is replaced with an advantage of i

essentially continuously, which can be done by supplying coal and coking this in the reactor space. Thereby, precoking can

happen, and by burning combustible components in the reactor room

met generated excess heat is stored in the same way as described above with reference to other embodiments of the present invention.

Due to the large contact surface which, according to the inven-

after heated coke layers form, the method according to the invention can

can also be advantageously adapted in connection with the extraction of at least one relatively volatile metal or metal compound, for example

show consisting of, or respectively containing, at least some of the metals zinc, lead, arsenic, antimony, cadmium and tin from one of the aforementioned

te metal in oxide and/or sulphide form containing melt, for example a slag obtained by smelting copper ore, whereby the melt is made to pass through the inductively heated coke layer, and where the residence time for the melt and the temperature in the coke layer are set so that the metal oxides during successive consumption of the coke layer is reduced and the metals are evaporated, respectively the metal compound is made volatile. The evaporated metal or metal compound can be oxidized by oxidizing combustion of combustible components in the reactor space and recovered in oxide form from the combustion gases outside the reactor. It is also possible to divert the vaporized metal or metal compound from the reactor space and recover the same in solid or liquid form by condensation outside the reactor space. If the smelt further contains at least one oxide-bound, relatively heavy-volatile metal, such as iron or silicon, this metal can be extracted at the same time in the above-described manner for the extraction of at least one metal from one of the aforementioned metals in oxide-bound form containing melt. Coke to replace the coke consumed in the coke bed can be supplied, or produced, as described with reference to other embodiments of the method according to the invention.

This also applies to the draining of the metal melt and slag from the reactor space, as well as the supply of additional heat to the reactor space and the batch therein, respectively safeguarding the unused heat content in the reactor space in gases or gas-forming components formed during the reduction and possibly added to the reactor space.

In reactors of the type in question, the electrical insulation between the induction coil (winding turn), and in the event of partial induction coils, can cause certain problems if the reactor walls show a certain degree of gas permeability. Among other things, it has been shown that carbon monoxide-containing gas can in certain cases penetrate from the batch through the reactor wall and cause carbon precipitation, which can lead to overflow in the coil. These problems will be accentuated by the construction of very large, inductively heated reactors and furnaces, whereby it may be necessary to resort to voltages that have not been used up to now within the induction heating technique. It is particularly serious that the repair of an induction coil carried out according to known technology often entails an expensive total disassembly, which, according to the present method, would entail unacceptable operating technical and financial consequences.

However, it has proven possible to a surprisingly high degree

to prevent flashover in the induction coil when the method according to the invention is carried out in a reactor with wall members that separate the induction coil from the reactor space, and which exhibit a certain gas permeability if a gas is fed to the mentioned wall members that is under a pressure that exceeds the highest pressure that prevails within the part of the induction coil which is arranged inside the zone of the reactor space, and which gas cannot maintain a conductive connection between the reactor chips.

A suitable precaution can therefore be to prevent the pressurized gas, which is fed to the aforementioned wall member, from flowing out in one direction from the reactor space. This can happen, for example, by keeping at least the part of the induction coil that is covered by the reactor enclosed in a pressure chamber. In this way, the gas under pressure can be suitably fed to the wall organs via the pressure chamber. According to another example, in connection with the aforementioned measures, the areas between delimited coil windings can be sealed against the atmosphere surrounding the reactor, whereby the pressurized gas is supplied within these sealed areas.

However, the risk of flashover between the windings of the induction coil cannot be completely eliminated. It has therefore proved advantageous to combine the method given above with precautions which enable the repair of parts of the induction coil without having to carry out a total dismantling of the reactor. This can be done by using one of several, up to 180° enveloping element-built induction coils.

It can also often be advantageous to use an induction coil made up of several partial coils. Furthermore, each coil winding can be arranged in one plane. This results in separate individual windings that can be connected to partial windings with a suitable number of thorns.

The advantage of this arrangement is

that it enables a constructively simple design of the insulating seal between the coil windings with gas blowing as indicated above,

that it offers the greatest imaginable opportunity for adaptation of the partial coil

Thorn number to the electrical nature of the heated medium,

that it simplifies the division of the coil into elements and at the same time facilitates the replacement of these, and

that it makes it easier to accommodate the expansion that usually occurs during operation of a reactor, while maintaining gas density for the latter.

An advantage of planar single-thorn coils is that when connecting the windings, sub-coils with an appropriate number of thorns will only be made so that the voltage 0 occurs between the delimiting windings of two sub-coils. This is possible if the delimiting partial windings are given different winding directions and at the same time adjacent ends of the delimiting partial windings are connected to the same point in the power supply system. With this arrangement, it is avoided that the gap between two partial coils is loaded with the high voltage that corresponds to the voltage between the windings in a

part coil times the number of thorns in it.

The, as stated above, pressurized gas will flow into the space where the material subjected to heating is located and through the gas-permeable wall members. It is therefore important to choose a gas which, with regard to the type of heating process, has a harmless composition. In cases where there is a risk of carbon precipitation in the wall members, it may be advantageous to use an essentially inert gas that has such an oxygen or hydrogen potential that carbon precipitation is prevented at least at the parts of the wall members that are adjacent to the induction coil.

The invention shall be described in the following with reference to the attached drawings, whereby the excellent features and advantages of the invention will further become apparent. The drawings schematically show in vertical section a number of facilities for carrying out different embodiments of the method according to the invention. Fig. 1 shows a plant for coking coal according to the invention,

Fig. 2 shows a plant for reduction and/or gasification

of gaseous media according to the invention,

Fig. 3 shows a plant for the reduction and possible subsequent carbonization or gasification of a solid, metal oxide material according to the invention, Fig. 4 shows a plant for melting waste according to the invention, Fig. 5 shows a plant for treating melts, especially slag melts according to the invention . Fig. 6-9 shows a vertical section of a part of a reactor wall with four different devices to avoid flashover in the induction coil. Fig. 10 is a partial plane section of an induction coil which is made up of several elements with a small wrap angle. Fig. 11 is a partial perspective section of one according to fig. 9 and IO designed induction coil. Fig. 12 is a partial side section of two partial coils made up of two planar coil windings, which partial coils are supplied with strdm in the preferred manner.

In the various figures, matching or essentially matching details are denoted by the same reference numerals11.

In fig. 1 shows a coking reactor whose walls are at least partially made up of a refractory lining 10 and a mantle 11 of, for example, steel sheets. An induction coil 12 is arranged around the reactor, which is supplied with alternating current from a power source not shown, with a cover device 13 arranged outside the induction coil, and where the coil serves to maintain a suitable temperature for the process in the layer 14, which essentially consists of coke.

The reactor according to fig. 1 includes an upper part 16, which is open at the bottom, suspended in beams, a rotatable part 17 and a stationary bottom 18. The lower part 17, which is connected to the upper part 16 via a water lock 19, is supported by a number of cooperating pairs of bearing and support rollers, one of which is shown at 21 and 22. The part 17 is essentially formed by a liquid-permeated dress mantle 23 which in turn supports a tooth ring 24, and which is turned by means of a motor-driven gear wheel 25 that engages in the tooth ring on the inside the part 17 is provided with a number of discharge vanes 26, which, when the part 17 rotates, discharge the coked material through a space between the part 17 and the bottom 18. The bottom 18 is bowl-shaped and together with the bottom part of the part 17 forms a water trap 27.

When coking coal in the reactor according to fig. 1 is supplied, the coal is fed to the reactor space through openings 28 arranged above the induction coil 12 and sinks through the feeding action of the vanes 26 down through the reactor space and past the level of the coil 12, at which it is heated to coking temperature and forms the inductively heated layer 14. Before the coal supplied to the reactor reaches the coil 12 level, it has been coked to a significant extent by the influence of, among other things, conduction and radiation heat from the coke layer 14. The inductively obtained heat is thus formed in a part of the material that is coked, which is essentially completely freed of gasifiable components. Before the coke leaves the reactor, it is cooled in the liquid lock 27, and it is also cooled in the jacket jacket 23.

The coal is supplied essentially continuously to the reactor space. For supplying the coal, a number of so-called stokers are used in the example shown, each including a funnel 29, the outlet of which opens into a pipe line 30, which in turn opens into the reactor room at 28. At the end of the line 30 facing away from the reactor room, a pressure cylinder 31 is arranged , which provides a feed of carbon from the funnel 29 to the rudder line 30 and to the reactor room. Only one stoker and one outlet 28 from the other stoker is shown in fig. 1.

The coking reactor has a lower and an upper drain line 32 and 33, respectively, which can be used separately or simultaneously for removal of the gas formed during coking in the reactor. The lower waste pipe line 32 is connected to the reactor space at a place below the induction coil 12 via an annular channel 34 and a number of openings 35. Above the coil 12 is arranged a number at 36 opening pipelines 37 for the supply of preferably liquid hydrocarbon to the coal being coked. In the space above the batch, a number of burners 38 are arranged, including a pipe line 39 for the supply of fuel, and a pipe line for the supply of oxygen-containing gas, such as air. The combustion gases from the burners 38, of which only one is shown in fig. 1, passes into the furnace space via openings 41, which are so directed that a vortex formation occurs in the space above the coal charge. Optionally, above the rate, only air or other oxygen-containing gas is supplied to burn the gases formed during coking.

By using only the upper waste line 33, whereby the waste line 32 is thus closed by means of a valve device not shown, the gases formed in the reactor space as the coal is coked pass up through the reactor space and out through the waste pipe 33. For preheating the coal and introduction of the coking process, the coking off-gases formed during the coking, rising through the coal charge, are evenly burned through the pipe lines 37, possibly added hydrocarbon above the charge while utilizing the burners 38. The heat content of the gases exiting through the discharge pipe line 33 is suitably taken care of for producing, for example, steam or electrical energy.

By using only the lower drain line 32, whereby the drain line 33 is kept closed by means of a valve device not shown, the gases formed during the coking pass through the openings 35, the annular channel 34 and the drain line 32 out of the reactor space. It is conceivable, by means of the burners 38, to maintain a certain reducing combustion above the rate for supplying part of the energy required for the coking process.

Through the lines 37, hydrocarbon is supplied, which on its passage through layer 14, where the temperature exceeds that necessary for cracking the hydrocarbon, is cracked, which results in a precipitation of carbon on the coke formed, the quality of which is thereby increased to a significant extent.

The gases exiting through the waste line 32 which are rich in combustible components can advantageously be burned to generate electrical energy for inductive heating of the coke layer 14 itself. According to the embodiment example shown, the physical heat content of gases exiting through the rudder line 32 is collected in an indirect heat exchanger 42.

Alternatively, gas is diverted both through lines 32 and 33, whereby an oxidizing combustion can advantageously be maintained in the furnace room above the coal charge and ensure that all of the oxidizing gases thus formed are led out of the reactor room through the drain line 33, and that only part of the coking gases and part of the cracking gases formed by the introduction of hydrocarbon via the rudder lines 37 leave through the drain line 32.

In fig. 2, the reference numerals 10 - 14, 32, 34, 35 and 42 have the same meanings as in fig. 1. By the one in fig. 2 showed reactor for reduction and/or gasification of gaseous media by bringing these into contact with the inductively heated coke layer 14, such a high temperature is maintained in the reactor space that the remains of the carbon consumed in the process are obtained in molten form in the lower part of the reactor. The molten coke residue 43 is drained off continuously or, as shown, interrupted, by means of a drain hole 44 and a chute 45. The gaseous medium, for example water vapour, which is to be reduced and/or carbonised, is supplied through a pipe line 46, after it has been heated in the indirect heat exchanger 42 with the reduced and/or carbonized gas leaving the reactor via the rudder line 32, and is carried out through the opening 35 which is directed obliquely downwards to prevent coke from passing into the annular channel 34 and clogging it. Coke or alternatively coal, which during its passage towards the coil 12 level is coked inside the reactor space, is fed into the reactor space by means of a feeding device 47 to replace the coke consumed in the layer 14.

If the material fed through the feeding device 47 is made of coal, this comes during its passage towards the level of the coil 12 and is coked, whereby the coking gases after cracking in the layer 14 leave together with the reduced and/or carbonized gaseous medium through the line 32. Should the coal be of poor quality quality, it is appropriate that by means of line 48 hydrocarbon is introduced in such quantity and such conditions are maintained in the furnace that when the hydrocarbon is cracked, it results in carbon precipitation on the newly formed coke, whereby its mechanical strength is significantly improved.

In fig. 3 shows a reactor for the reduction and melting of iron oxide powder. With regard to the meaning of the designations 30 - 14, 37 - 41, 44, 45 and 47, reference is made to the description of fig. 1 and 2 above. The upper part of the reactor is designed as the radiation part in a not shown, to the reactor connected steam boiler. Thus, the upper part of the reactor chamber is surrounded by a mantle 49 through which water or steam flows, which in turn is enclosed by a heat-insulating jacket 50. The material supply line 51 from the feed device 47, which extends downwards, is double-walled and is flowed through in the same way as the jacket 49 by a liquid or gaseous heating medium. In the area below the coil 12, the reactor wall is cooled using the jacket cap 52.

Through line 51, a material consisting of iron oxide, coke or alternatively coal, which is precoked in the reactor space as described above, as well as any slag-forming agents, is fed on top of the layer which essentially consists of coke. Liquid or gaseous hydrocarbon can be added to the charged material through the line 37, which material is preheated by means of the burners 38.

The thus preheated iron oxide material is reduced and metallized to a certain extent above the coke layer and is fused with the slag-forming material in the upper part of the induction zone, after which the iron oxide is finally reduced and carbonized during the passage through the coke layer 14 during successive consumption of this, whereby the layer 14 however in a similar degree is maintained by the added coke or the added coked coal. The molten material is obtained under the layer in the form of a slag layer 53 and a carbonaceous iron layer 54. The iron layer can be intermittently drained through the drain hole 44. The slag is conveniently drained essentially continuously through the drain hole 55 and the chute 56. The drain hole is for this purpose provided with a movable, by means of a drive arrangement not shown driven, stopper 57, which is maneuvered so that the boundary between the layer 14 and the slag layer 53 is kept at a desired level in the reactor space. The carbon dioxide-containing gas formed during the reduction, as well as residues of any added hydrocarbon through the pipe line 37 and any coking gases are burned by means of the burners 38 above the material added to the reactor. The reactor according to fig. 3 can also be advantageously used for final reduction and melting of contaminated iron oxide, for example sponge iron. The reactor according to fig. 3 can also be used for the reduction and eventual carbonization or carbonization of other, solid metal oxide-containing material, for example for the production of molten calcium carbide, whereby calcium oxide and carbonaceous material are supplied through line 51.

In fig. 4 where the designations 10 - 14, 28 - 31, 44, 45 and 52 - 57 have the same meanings as indicated in fig. 1-3, a reactor is shown for melting piece-shaped, wholly or partially metallic material, in particular inferior metal scrap, such as metal shavings and the like. The scrap is fed together with coke or coal, and possibly also together with slag-forming agents using stokers 30 and 31,

to the inductively heated coke layer 14. Above and in layer 14, the scrap is melted both inductively and by contact with hot coke layers, whereby molten coke ash and slag together with the melted and refined scrap material are obtained as molten layers 53 and 54 respectively below layer 14. Formed gas leaves through line 58. If coal is supplied to the reactor chamber, it is ensured that this is at least substantially coked before it reaches layer 14. Liquid or gaseous hydrocarbon can, if desired, be supplied to the charged material, and the material can be preheated in the reactor chamber by combustion of combustible constituents therein, as described with reference to fig. 1-3. The boundary between the slag bath 53 and the coke layer 14 is kept at the desired level by a corresponding draining of slag through the drain hole 55.

In fig. 5 where the designations 10, 12 - 14, 44, 45, 47, 49 - 52 and 55 - 57 have the same meaning as indicated in fig. 1-4, a reactor is shown for extracting at least one relatively volatile metal or metal compound, and at least one relatively volatile metal from, for example, a slag smelter. In the reactor, a coke layer 14 is maintained at the level of the coil 12, to which the slag melt is fed continuously or in batches. In the embodiment shown, the slag melt is fed from a hopper 59 to a chute 60, from which the melt is distributed over the layer 14 with the help of a number of distributor 61 installed in the reactor space. The layer is kept at such a temperature that the volatile metal or metal compound, for example zinc and/or lead in oxide or sulphide form, are gasified and leave the reactor space, possibly after burning them with the help of an oxygen-containing gas, for example air, which is supplied through supply lines 62. The combustion of the slag is carried out through the coke layer 14, where heavy-volatile metal oxides, for example iron oxide, are reduced and carbonized in contact with the layer during successive consumption of this. The layer 14 is filled in step with the consumption by supplying new layer material, possibly together with suitable slag formers via the supply pipe 51. The reduced metal is obtained in the form of a lower molten layer 63 in the bottom of the reactor, while the combustion of the added and formed slag is obtained in the form of a slag layer 64 lying on the layer 63. The boundary between the slag layer 64 and the coke layer 14 is kept at the desired level with a continuous or interrupted draining of slag from the layer 64.

In fig. 6 shows part of a reactor wall including a ceramic insert 10 and a jacket 11. 12 denotes an outside

the introduction 10 is arranged with an induction coil which is made up of rudders which can be cooled by feeding a cooling liquid through them. The coil 12 is partially baked into the ceramic filler 65. Both the insert 10 and the filler 65 are to a certain extent gas permeable.

In order to prevent the passage of solid, liquid or gaseous materials to the coil 12 from the part of the coil which is opposed to the reactor wall, i.e. from the reactor space containing the material to be heated, a wall member 10, 65 in height with the coil 12 is maintained by means of a gas, a pressure that exceeds the highest pressure that prevails within the zone of the reactor space located opposite the induction coil. The gas used is chosen so that it is not able to create electrically conductive connections between the coil windings in the coil 12. The aforementioned pressure is maintained by introducing gas under pressure, for example air or an essentially inert gas, through the supply pipe 66 to the induction coil 12 against the atmosphere-sealed pressure chamber 67.

In fig. 7 also shows a part of the reactor wall with insert 10, filler 65 and induction coil 12. The areas between adjacent coil windings are sealed against the atmosphere surrounding the reactor by means of the sealing device 68 of suitable insulating material. In the device 68, a number of holes 69 are arranged through which gas under pressure, as indicated by means of arrows, can be introduced to the levels in the coil 12 adjacent to parts of the reactor wall 10 and 65.

Fig. 8 shows an embodiment which is in principle consistent with the embodiment according to fig. 7. A portion of a reactor wall formed by liner 10 and filler 65 is enclosed by a spirally wound induction coil 12. The seal between adjacent coil windings is obtained by means of a similarly spirally wound hose or similar 70 of an elastomeric material. In order to achieve small, and thus more effectively sealing contact surfaces between the hose 70 and the winding 12, a rudder 71 with a small diameter is welded to the latter. The hose 70 simultaneously serves to supply gas under pressure to the wall members 10 and 65, and for this purpose is connected to a pressure medium source, not shown, and partially provided with gas outlet openings 72 directed towards the reactor wall.

In fig. 9 again shows a portion of a reactor wall consisting of the liner 10 and the filler mass 65 and enclosed by the induction coil 12. Each coil winding has a parallel trapezoidal cross-sectional shape and is provided above and below with protruding flange members 73. Between adjacent flanges 73 of adjacent coil windings, seals 74 of an elastomeric material are arranged, which are provided with holes 75 for feeding gas under pressure to the filling mass 65 A number of holes distributed lengthwise along the coil winding are arranged in the seal 74 between successive coil windings. The gas is fed to these holes 75 through distribution lines 76, which extend from a common supply pipe 77 for a number of distribution lines 76.

In fig. 10 shows how each coil winding in the coil 12 can be made up of several elements 78a>-d suitably arranged in one and the same plane, each of which encloses an angle which is less than 180°C. With 79 are designated lines for lining cooling liquid and possibly also electric current between nearby elements 78a - d, and with 80 are designated sealing means, which seal between nearby ends of the elements 78.

In fig. 11 shows in more detail the connection point between two adjacent elements 78a, 78b according to fig. 10, where each element essentially has the design shown in fig. 9. The flanges 73 in one element 78a end at a distance from its end, while the other element 78b exhibits a flange 81 that exceeds the element 78a. The closure between adjacent element ends takes place by means of a between the inside of the flanges 81 and the outside of the element 78a in- clamped sealing device 82, which enables a certain movement between the elements 78a, 78b in their longitudinal direction.

In fig. 12 shows an induction coil which is made up of two partial coils, each of which consists of three coil windings 83 - 85, respectively 86 - 88. Each coil winding is arranged in one and the same plane and can be divided into elements on the one in fig. IO showed way. Seals 89 are arranged between the opposing ends of each coil winding and between the adjacent coil windings. 90 denotes supply lines for the supply of electric current to the partial coils 83 - 85 and 86 - 88. The current is taken from the supply lines through contact means 91 - 94, while the current is led between delimited coil windings in each sub-winding by means of contact means 95 - 98. As can be seen from the figure, the sub-coils 83 - 85 and 86 - 88 have different winding directions, and their adjacent ends of the sub-coils are in principle connected to the same point in the power supply system, whereby the voltage between the coil windings 85 and 86 is constantly "zero.

The advantages achieved by the method according to the invention are illustrated by the following examples:

Example 1

A coke layer with a diameter of 7.0 m and a height of approx.

5 m is kept in a reactor of the one in fig. 1 shown type at a temperature of approx. 1000°C. From the underside of the layer, coke is continuously discharged in an amount of approx. 74.5 tonnes/24 hours, while the layer is continuously built up by supplying coal to the upper side of the layer. The coal, which contained 29% by weight of volatile components (based on combustible substance) and 12% by weight of ash, is added in an amount of approx. lOO tonnes/24 hours and is coked in the reactor while giving off gases. Energy in an amount of HO MWh/24 hours is supplied to the coke bed electro-inductively at a frequency of 100 Hz by means of an induction coil which surrounded the reactor at a level with the coke bed, and which had a diameter of 7.5 m and a height of 4 .5 m. The aforementioned energy was sufficient to maintain the layer temperature and for coking the coal. The amount of coke formed amounted to approx. 60,000 Nm /24 hours and mainly consisted of hydrogen and hydrocarbon.

Example 2

A gas consisting essentially of 20 volume% CO„ and the rest CO and H2 is fed continuously in a quantity of 220,000 Nm /24 hours through a reactor of the one in fig. 2, and which contained an electro-inductively heated coke layer according to example 1. The gas supplied to the reactor was preheated to the layer temperature, which was approx. 800°C. The reduced gas that left the reactor and that had passed through the layer consisted of CO, H and hydrocarbon, and their amount was approx. 283.OOO Nm /24 hours. Energy in an amount of 100 MWh/24 hours was supplied electro-inductively to the coke bed with a frequency of lOO Hz by means of an induction coil according to example 1. To replace the consumed coke, coal of the type specified in example 1 was supplied, and in an amount of approx. 35 tonnes/24 hours and in the course of the same time 4 tonnes of ash were removed from the reactor.

Example 3

For an electro-inductively heated coke bed, according to example 1, which was kept in a reactor of the type shown in fig. 3, and which was kept at a temperature of approx. 1500°C, pre-reduced iron oxide with a composition which essentially corresponded to FeO in an amount of 72 tonnes/24 hours is continuously fed together with coal of the type indicated in example 1, which was added in an amount of 19 tonnes/ 24 hours. Molten pig iron in a quantity of 55 tonnes/24 hours, and with a carbon content of approx. 4% by weight, together with molten slag in a quantity of 6 tonnes/24 hours. From the upper part of the reactor, a gas consisting essentially of hydrocarbon and carbon monoxide was extracted in an amount of 30,000 Nm 3 /24 hours. In order to cover the energy requirement for maintaining the bed temperature and for carrying out the reduction, the coke bed was supplied with 90 MWh/24 hours by means of an induction coil as described in example 1 at a frequency of 100 Hz.

Example 4

Iron oxide material was reduced in the manner described in example 3, with the exception that oil in an amount of 20 tonnes/24 hours was burned in the reactor above the layer. The need for electrical energy thereby fell to 70 MWh/24 hours for the same amount of pig iron produced, while at the same time the amount of gas withdrawn from the reactor reached approx. 215.OOO Nm /24 hours, and the said gas mainly consisted of carbon dioxide and water.

Example 5

For an electro-inductively heated coke layer, according to example 1, which was held in a reactor of the one in fig. 4 shown type and at a temperature of 15CO°C, iron scrap containing 90% by weight iron metal in an amount of approx. 200 tonnes/24 hours together with coal of the type specified in example 1 and in a quantity of 7 tonnes/24 hours. Molten pig iron was drained from the lower part of the reactor in an amount of approx. 195 tonnes/24 hours and approx.

0.5 tonnes of slag/24 hours. A gas consisting of carbon monoxide, hydrogen and hydrocarbons in an amount of approx. 15.OOO Nm /24 hours. In order to cover the energy requirement for maintaining the bed temperature as well as for melting the scrap and reducing its oxidizing constituents, 96 MWh/24 hours were supplied to the coke bed by means of an induction coil according to example 1 and at a frequency of lOO Hz.

Example 6

For an electro-inductively heated coke layer, according to example 1, which was held in a reactor of the one in fig. 5 shown type,

and at a temperature of 1500°C, molten fayalite slag was continuously added at a temperature of 1450°C and with an iron content of approx. 50% by weight in a quantity of approx. 200 tonnes/24 hours together with limestone in a quantity of approx. 90 tons/24 hours and 45 tons/24 hours of the coal described in example 1. Molten pig iron in an amount of 97 tons/24 hours was drained from the lower part of the reactor together with molten slag in an amount of 120 tons/24 hours and with a composition that essentially corresponded to wollastonite. A gas consisting essentially of carbon dioxide, carbon monoxide and hydrogen, and in a quantity of o 64,000 Nm 3/ 24 hours, was extracted from the upper part of the reactor. In order to cover the energy requirement for maintaining the bed temperature and for carrying out the reactions, 130 MWH/24 hours were added to the coke bed using the induction coil according to example 1 at a frequency of 100 Hz.

Example 7

For an electro-inductively heated coke layer, according to example 1, which was held in a reactor of the one in fig. 5 shown type and at a temperature of 1500°C, a slag obtained by electric copper slag melting with a temperature of 1250°C and containing 10% by weight Zn, 2% by weight Pb, 43% by weight FeO and re-

stone essentially SiO,,. The slag was added in a quantity of approx. 150

tons/24 hours together with 22 tons/24 hours of the coal that was described

know in example 1, and limestone was added in an amount of 110 tonnes/24 hours. Molten iron with a low carbon content was drained from the lower part of the reactor in an amount of HO tonnes/24 hours and with a silicon content varying between 2 and 6% by weight, together with molten slag in an amount of 75 tonnes/24 hours and with a composition which essentially corresponded to wollastonite. A gas was formed in the coke layer in an amount of approx. 54.OOO Nm 3/24 hours. To remove from the reactor this gas, which, in addition to H^, CO and C02, contained 13 tonnes of Zn and 3 tonnes of Pb in vapor form, the gas was supplied with air to oxidize the Zn and Pb content. The thereby obtained metal oxides were separated in

form of fine dust from the remains of the gas in a subsequent steam boiler

and gas cleaning device.

Claims (41)

1. Procedure for carrying out heat-demanding chemical and/or physical processes in a reactor space, containing a layer consisting essentially of a material participating in the process, whereby at least part of the energy required for the process is generated electro-inductively in the layer itself using at least one induction coil placed outside the reactor space and through which alternating current flows, characterized by using a layer with a resistivity (?) in the range of 10 _4 and 10 ohms and an alternating current with a low frequency, which is at most 10 times the mains frequency, whereby the mains frequency is 50 Hz, and that a ratio between the smallest cross-sectional dimension (d) of the layer area and the inductive field's penetration depth (<5) of between 0.2 and 2 is maintained .5, which ratio is determined by the equation y- = k (0.54 - 0.35-<10>log5>), where k is a number in the range 1.1-1.5, preferably approx. 1.2. 2. Method according to claim 1, characterized by using the mains frequency or a frequency that is an integer multiple of the mains frequency. 3. Method according to claim 1 or 2, characterized in that part of the heat required for the process is supplied to the reactor by burning combustible components therein. 4. Method according to claims 1-3, characterized in that a layer material essentially consisting of coke is used. 5. Method according to claim 4, characterized in that it is applied in connection with the coking of coal, which is preferably at least mainly continuously fed through the reactor space, whereby the inductively obtained heat is formed in a part of the material being coked which is essentially completely free of gasifiable components. 6. Method according to claim 5, characterized in that the resulting coke is discharged from the reactor space via a liquid lock in which the coke is cooled. 7. Method according to claim 5 or 6, characterized in that at least part of the coking gas is caused to pass through coking material occurring in the reactor space, in which at least one temperature necessary for cracking the coking gas is maintained. 8. Method according to claim 4, characterized in that it is adapted in connection with the reduction and/or carbonization of a gaseous medium, which is essentially caused to pass through the inductively heated coke layer during successive consumption thereof. 9. Method according to claim 8, characterized in that the layer temperature is kept so high that the slag formed by the consumption of coke in the layer is obtained as a melt at the bottom of the reactor chamber, whereby the slag melt is intermittently or continuously drained from the reactor chamber. 10. Method according to claim 8 or 9, characterized in that the gaseous medium is preheated by indirect heat exchange with the reduced and/or carbonized gas. 11. Method according to claims 7 - 10, characterized in that the gas is made to pass downwards through coke occurring in the reactor space. 12. Method according to claim 4, characterized in that it is adapted in connection with reduction and possible subsequent o<p>pcar-cajixanization of or formation of carbides of solid, metal oxide-containing, especially iron oxide-containing or calcium oxide-containing/material which is supplied to the coke layer present in the reactor space in which the induction current is formed, whereby at least in the coke layer such a temperature is maintained that the metal oxide-containing material during reduction and melting, as well as possibly during carbonisation or the formation of carbides from these, is fed through the coke layer during successive consumption of this, during which the formed slag and metal or metal-carbide melt is continuously or intermittently drained from the reactor space. 13. Method according to claim 12, whereby the metal oxide-containing material is made of iron oxide material, characterized in that the iron oxide material is supplied to the reactor chamber in a pre-reduced state, preferably in a pre-reduced state at least to FeO. 14. Method according to claim 12 or 13, characterized in that the metal oxide-containing material is supplied to the reactor space in such a finely divided state that, at least during the initial stage of its reduction, it is kept fluidized by the gases formed in the reactor space. 15. Method according to claim 4, characterized in that it is adapted in connection with the melting of piece or non-article-shaped, fully or partially metallic material, for example pre-reduced metal oxides, such as sponge iron or metal scrap, such as iron scrap, especially low-grade metal scrap, such as metal shavings or the like, whereby the aforementioned material together with a reducing agent to replace the coke consumed in the process is fed to the reactor in which the material is electro-inductively melted down, and that the molten material passes through the thus inductively heated coke layer during a possible final reduction of oxidizing parts of the material and possibly that the molten metal is carbonized during successive consumption of the coke layer, whereby the molten metal and formed slag are obtained in a zone located below the coke layer from which the metal and slag are continuously or intermittently drained from the reactor space. 16. Method according to claims 12 - 15, characterized in that the solid, metal oxide-containing or metallic material is preheated before it is introduced into the reactor space. 17. Method according to claim 4, characterized in that it is adapted in connection with the extraction of at least one metal, such as iron and silicon, from a melt containing one of the mentioned metals in oxide-bound form, for example a slag, whereby the smelt is fed to the coke layer, and the residence time for the smelting and the temperature in the coke layer are set so that the aforementioned oxide-bound metal is reduced during successive consumption of the coke layer and is obtained in molten form in a zone below the coke layer, from where this, together with the newly formed and possibly remaining slag, is continuously or intermittently drained from the reactor space. 18. Method according to claim 4, characterized in that it is adapted in connection with the extraction of a relatively volatile metal or metal compound, for example consisting of or containing at least one of the metals zinc, lead, arsenic, antimony, cadmium and tin, from a melt which contains at least one of the aforementioned metals in oxide and/or sulphide form, for example a slag, such as a slag obtained by smelting copper ore, whereby the smelt is made to pass through the inductively heated coke layer, and that the residence time and temperature in the coke layer in- is added so that the metal oxide during successive consumption of the coke layer is reduced, and the metal is evaporated or the metal compound is evaporated. 19. Method according to claim 18, whereby the melt further contains at least one oxide-bound, relatively volatile metal, such as iron or silicon, characterized in that the residence time for the smelting and the temperature in the coke layer are adjusted so that the aforementioned oxide-bound metal is reduced during successive consumption of the coke layer and is obtained in molten form in a zone below the coke layer, from which this together with treated slag is continuously or intermittently drained from the reactor space. 20. Method according to claim 18 or 19, characterized in that the evaporated metal or metal compound is oxidized by oxidizing combustion of combustible components in the reactor space and is recovered in oxide form from the combustion gases outside the reactor. 21. Method according to claim 18 or 19, characterized in that the evaporated metal or metal compound soi is fed out of the reactor space and recovered in solid or liquid form by condensation outside it. 22. Method according to claims 12 - 21, characterized in that the metal melt or metal carbide melt and the slag melt are tapped off separately. 23. Method according to claims 9 - 22, characterized in that a layer of molten slag is retained under the coke layer and that heat is developed inductively also in the slag melt. 24. Method according to claims 8 - 23, characterized in that the coke consumed in the coke layer is essentially replaced continuously. 25. Method according to claim 24, characterized in that coke to replace the consumed coke in the layer is produced in the reactor space by adding coal to and coking the coal in it. 26. Method according to claims 5 - 7 and 25, characterized in that the coal is preheated, preferably during the starting coking stage, by combustible components being burned in the reactor space and the heat of the combustion gases being transferred to the coal by radiation and convection. 27. Method according to claims 5 - 26, characterized in that hydrocarbon is supplied to the reactor space. 28. Method according to claim 27, characterized in that the hydrocarbon is brought into contact with the coke and/or the coal undergoing coking, and that this material is at least kept at such a temperature that the hydrocarbon is cracked and causes carbon precipitation on the coke. 29. Method according to claims 3 - 28, characterized in that the heat developed by the aforementioned combustion of the combustible components, which is not taken up by the material in the reactor space, is recovered x a radiation part arranged therein. of one to the reactor to attached steam boiler. 30. Method according to claims 5 - 28, characterized in that at least part of the combustible gases formed in the reactor space are utilized for the production of steam or electrical energy, for example by means of a steam or gas turbine, suitable hot air turbine. 31. Method according to claim 30, characterized in that the generated electrical energy is utilized for the process's energy supply. 32. Method according to claims 1 - 31, whereby a reactor is used with a wall element which separates the induction coil from the reactor space and which exhibits a certain gas permeability, characterized in that a gas is fed to said wall element which is under a pressure that exceeds the highest pressure that prevails in the zone of the reactor space within the induction coil, and which gas lacks the ability to maintain an electrically conductive connection between the coil windings. 33. Method according to claim 32, characterized in that the pressurized gas supplied to the wall members is prevented from expanding through the wall members in the direction from the reactor space. 34. Method according to claim 33, characterized in that at least the part of the reactor covered by the induction coil is kept enclosed in a pressure chamber. 35. Method according to claim 34, characterized in that the gas is fed to the wall organs via the pressure chamber. 36. Method according to claim 33, characterized in that the area between adjacent coil windings is sealed against the atmosphere surrounding the reactor, and that the gas is supplied within said sealed area. 37. Method according to claims 32 - 35, characterized in that one of several, at most 180° enveloping element made up of an induction coil is used. 38. Method according to claims 32 - 37, characterized in that one uses one of several partial coils made up of an induction coil. 39. Method according to claims 32 - 38, characterized in that each coil winding is arranged in one plane. 40. Method according to claim 38 or 39, characterized in that adjacent partial coils are given different winding directions and that close to each other ends of adjacent partial coils are connected to the same point in the power supply system. 41. Method according to claims 32-40, characterized in that an essentially inert gas is used which has such an oxygen or hydrogen potential that carbon precipitation is prevented at least on the parts of the wall members located opposite the induction coil.