FI62232C - FOERFARANDE FOER ELEKTROINDUKTIV VAERMNING AV STYCKEFORMIGT MAERIAL I EN REAKTORKAMMARE - Google Patents

Description

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c (45) Patent granted 10 12 1902 Patent mecidelat ^ 1 ^ (51) Kv.iic? /int.a.3 B 01 J 19/08, 1 'H 05 B 6/10 FINLAND —FINLAND (21) Λ * · "» »» * · '"·' · —HtuntwStali ** 1227 / 7¾ 23.0k.Ti» vr / (23) Alkuptlvt — Glltlghutadif 23-0¾ ^ ¾ (41) Tullut (ulktMkil - SIMt uffwitHg 31.10.7¾ rMMtti And the registry board · (44) NiMvUu) pMon „kwMttlkihun pvm.-

Patent. öht registerutyrelsen 1 Amttlcan utlacd odi ucUkrMten publlcarud 31.08.82 (32) (33) (31) Requested utuoUcuu * —eu * frd pHorh · * 30.0¾.73 01.03.7¾ Sweden-Sweden (SE) 7306063-¾, 7¾027¾7-5 (71) Boliden Aktiebolag, Sturegatan 22, Stockholm, Sweden-Sweden (SE) (72) Hans Ivar Elvander, Helsingborg, Ingvar Anton Olof Edenvall,

Helsingborg, Karl Göran Görling, Lidingö, Douglas Severin Ekman,

Helsingborg, Sweden-Sweden (SE) (7¾) Oy Kolster Ab (5¾) Method for electrically inductive heating of a particulate material in a reaction chamber - Förfarande för elektro-induktiv värmning av styckeformigt material i en reaktorkamare

The present invention relates to a method which can be used to carry out heat-requiring chemical and / or physical processes in a reaction chamber containing a substrate consisting essentially of process material, and at least some of the energy required for the process is produced by electrical induction in the substrate itself using at least one running alternating current #

The invention primarily relates to a method by means of which heat-demanding processes can be carried out in a coke substrate. Coke made from coal or lignite (lignite) of different ages, or coal produced by pyrolysis from other organic material, is used in the art to perform various operations in which the carbonaceous material is oxidized and / or associated with a compound or soluble in another substance. The term coke will be used in this specification for all carbon made by pyrolysis of organic material.

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The heat required in the above processes can be introduced into the reaction chamber in various ways. For example, if coke and other reactants can be preheated, heat can be generated in the reaction chamber by burning a portion of this coke, or heat can be introduced through the walls of the reaction chamber. Other methods are based on direct electric heating of the coke or reaction mixture. The latter method often has advantages over the above methods, despite the usually relatively high unit price of electrical energy. Among the advantages are less space-consuming equipment for both the process itself and the after-treatment of any exhaust gases »greater flexibility in process design» greater freedom of choice for different raw materials »good return on energy used and better choice of the most economically advantageous size for production equipment.

A very common way to generate electrical energy is to conduct current through the electrodes »whereby the reaction mass is heated by resistance heating or arcing.

Another way is to induce electric currents in the reaction mass by placing an electromagnetic alternating field »so-called inductive heating. This has been proposed for use, for example, in experiments in the manufacture of coal. Due to the relatively high electrical resistivity, it has been assumed in such cases that it is necessary either to use high frequencies in the switching field or to allow the material to be heated to form a secondary winding in a transformer-like device.

However, the use of high frequencies imposes certain technical and economic constraints. On the other hand, the transformer method »in which carbon or other material placed in the chute is allowed to form a closed circuit» is desired in many cases to be avoided.

it has now surprisingly proved possible to obtain particularly technically and economically advantageous results when carrying out processes such as those mentioned at the outset by the process according to the invention, which is characterized by the use of an alternating current of up to 10 times mains frequency and that the ratio of the smallest horizontal transverse dimension d of the layer to the induction depth S of the induction field is kept between 0.2 and 2.5. which is determined by the equation ** A *. , ► Λ 5 62232 where k is a number between 1.1 and 1.3 and is obtained from the equation * \ H5? ° m \ lύ · μ where i0 is the angle of the electromagnetic field frequency expressed in units Permeability of the layer expressed in H / m and jj * 8en resistivity expressed in m. The transverse dimension of the substrate surface area dimension d is then measured in meters * processes using low frequencies, and in this case it is not necessary to increase the transverse dimension of the substrate only to a relatively small extent compared to the dimensions required for the known heating of a low resistivity material with a low frequency alternating current. As an example, when inductively heating a coke substrate with a specific resistance of 10 ohms at an alternating current of 100 Hz, an induction coil diameter of only 7.5 »* proved to be suitable when the coil height to diameter ratio was 0.6.

According to the invention, it has been shown that very high amounts of energy can be generated in a coke substrate by means of an already relatively strong electromagnetic field. At the same time, it has been found that the losses due to inductive heating of the induction coil, if the coil is copper, have increased to only a few percent of the imported energy. In the above example, when the field strength was only 30 kA / m, about 30 MV in the coke substrate and the losses in the copper windings were developed only 600 kV, i.e. 2 of the imported energy.

Thus, by taking advantage of this extended principle of inductive heating, which can be used to heat a piece material in substrates with a resistivity of 10 to 10 ohms, the high resistivity previously considered an obstacle has now turned to advantage.

The method according to the invention naturally uses alternating current with the same frequency as the grid, in the event that it is desired to take energy from the grid, since thus both installation and operating costs can be kept low. If the frequency needs to be increased, a suitable alternating current with a frequency not higher than ten times the mains frequency, suitably an integer multiple thereof, preferably not higher than five times, is passed through the induction loop. Namely, in the indicated areas, current with the desired frequency, cheap and efficient, can be obtained, taking advantage of simple structures and ‘IV ·; j cheap motor- or turbine-driven generators, or alternatively 4 62232 ti frequency multipliers or thyristor-controlled current converters in those cases! which do not require very large amounts of power.

In summary, the following advantages over the prior art are achieved by the method of inductively introducing energy into a substrate having a resistivity of 10 to 10 .mu.m a by means of a current with a low or relatively low frequency: 1. It is possible to build reactors of considerable size units that develop significantly more power per unit volume and thus have a high return.

2. The penetration depth of the field is large in relation to the cross-section of the reactor, which results in a more even energy development over the entire cross-section.

3. Inductively, it is possible to develop amounts of energy that have not been possible before.

4 * The efficiency of electricity is improved as much as possible.

3 · Devices that can generate current with a desired low frequency will become simpler and cheaper and their electricity efficiency will become high; can often be used to take advantage of network frequency.

In the process according to the invention, it is not necessary to introduce all the necessary heat electroinductively, but within the framework of the present invention it is possible to introduce some of the heat required in the process into the reaction chamber by burning combustible substances there.

The invention can be advantageously applied in connection with the carbon experience, which is most preferably fed at least almost continuously through the reactor chamber during coking, and the inductively generated heat is generated in a part of the coking material which is almost completely released from the gaseous components. Since the inductive heat is then generated directly in the material to be coke, a rapid coking process is achieved so that a considerable amount of carbon per unit time can be coke in a relatively small device.

The coke formed is suitably removed from the reactor chamber via a liquid trap where the coke cools and thus many health disadvantages are avoided. In order to improve the quality of the tested material, at least part of the coke oven gas and / or the hydrocarbon introduced into the reactor chamber may be passed through the coke oven or almost fully oxidized material in the reactor chamber. precipitation of the tested material '1Λ *' ♦ · ·,. t 5 62232 on the surface. In this way, first-class coke, such as metallurgical coke, can be produced from secondary crude products.

Some of the heat required for coking can be obtained in the reactor chamber by directly burning combustible substances there, which are most preferably not in contact with the coked material. As combustible substances, all or part of the gases formed in coking can be used, but also fuel introduced from outside the reactor chamber, such as hydrocarbons, exclusively or partially. Such heat immediately generated in the reactor chamber can be suitably used for preheating or partially coking the carbon introduced into the reactor chamber. The heat generated in the combustion of combustible materials, which is not used to heat the material in the reactor chamber, can be recovered in the radiant part of the reactor chamber, which is connected to a steam pan built in connection with the reactor. Alternatively, at least a portion of the heat content of the gases formed in the test reactor can be utilized, for example, to generate steam or electrical energy. When electrical energy is produced, this can advantageously take place both here and in other embodiments of the invention by using a steam or gas turbine, suitably a hot air turbine. The electrical energy produced can be used to supply energy to the process, and the energy can then be produced in the form of an alternating current with a frequency equal to that used in that process. Likewise, the still warm air leaving the hot turbine can be utilized in the combustion in the above-mentioned reactor chamber, whereby a good thermal efficiency of the process is achieved.

The invention can also be advantageously applied in connection with the reduction and / or carburization of a gaseous medium, for example for the production of reducing or shielding gases, in which case a gaseous medium, which may be, for example, steam, circulating gases from reduction processes, optionally added hydrocarbons, etc., without interruption through an inductively heated coke substrate, consuming this continuously. As in the case of coking, this procedure also achieves a very high capacity in a reactor with even modest dimensions due to the fact that, due to inductive heating, heat generation takes place relatively evenly throughout the coke substrate. The temperature of the substrate can suitably be kept so high that, when coke is used, the slag formed in the substrate is obtained as a melt at the bottom of the reactor chamber and the slag melt is continuously or intermittently removed from the reactor chamber. In this way, the removal of residues from the use of coke from the reactor chamber is simplified. In order to keep the conditions 6 62232 uniform in the reactor chamber, it is suitable to replace the coke used in the coke substrate practically continuously. The coke required to replace the coke in the substrate can be produced in the reactor chamber by introducing carbon and coking it in the reactor chamber, making it possible to form a cheap raw material and improve the quality of the formed coke as described above for coking coal. the gaseous medium to be reduced and / or mapped can be preheated by direct heat exchange with the reduced and / or carburized gas. Likewise, some of the heat otherwise required for the coking and process can be introduced into the reactor chamber by direct combustion of combustible materials, and heat generated from combustion of combustible materials not consumed in the material and gases in the reactor chamber can be recovered inside or outside the reactor as described above for carbon experience. Combustion in the reactor chamber is carried out on the side of the coke oven substrate from which the gaseous medium to be reduced and / or carburized is introduced into the coke oven substrate. Particularly in such a case, from the karma of the gas transport and the structure, it is suitable to allow the gas to pass down through the coke in the reactor chamber. The physical heat content of the gases leaving the reactor can be suitably recovered by means of heat exchange between these gases and the gases introduced into the reactor.

Another field in which the process according to the invention can be advantageously used is the reduction of a solid metal oxide-containing material, in particular an iron oxide or potassium oxide-containing material, and possibly the subsequent carburization. The material is then introduced into a coke substrate in the reactor chamber, where an induction current is generated and at least a temperature is maintained in the coke zone such that the metal oxide-surfaced material passes through . In this case, poor quality coke can be used without disadvantage and a high and uniform temperature can be maintained in the entire coke substrate, so that the equipment required to carry out the process obtains excellent production efficiency compared to previously known reduction and melting equipment. The process can be used with particular advantage for the final reduction of a prereduced iron oxide material,. f, "'7 62232 as at least for the reduction of ferrous oxide material reduced to FeO. is at least at the initial stage of the reduction due to the formation of liquid gases rising from the substrate, so that the process is well suited for the reduction of fine-grained metal oxide materials such as feldspar, etc. The solid metal oxide-containing material can preferably be introduced into the reactor chamber warm or preheated.

Due to the different specific weights of the metal or metal carbide melt and the slag melt, to which suitable refining and melting agents can also be added to the latter melt, the metal or metal carbide melt passes through the slag melt and accumulates in the area below it. The metal or metal carbide melt and slag melt are most preferably removed separately from the reactor. Especially in the case where the slag melt has a refining effect, it is advantageous to keep a layer of molten slag under the coke base, whereby part of the heat required in the process can also be generated inductively in the slag melt.

The coke used in the test substrate is preferably replaced by adding carbon almost continuously and coking it in an oven chamber.

The hedgehog can be preheated and the coking process begins by burning combustible materials in a reactor chamber whereby the heat of the combustion gases acts by radiating or directing to the coal. The combustible gases can be, for example, a hydrocarbon which is introduced into the reactor chamber, either in the space above the charge or in the charge. The hydrocarbon can be contacted, for example, with the experiments and / or with the material to be coking, at the same time keeping this material at least at a temperature such that the hydrocarbon cracks and the carbon precipitates on the experiments. The heat generated in the combustion of combustible materials, which is not consumed by the material or gases in the reactor chamber, can be recovered inside or outside the reactor in the manner described above in connection with the coking of coal.

The open process of the invention can also be applied to the smelting of wholly or partly metallic materials in particulate or particulate form, for example pre-reduced metal oxides such as iron sponge or scrap metal such as iron scrap, in particular low cost scrap metal such as lathe chips and the like, and reducing agents to replace the spent coke are introduced into a reactor where the material is electrically inductively melted and the molten material also passes through an inductively heated coke bed, whereby oxidized portions of the material are finally reduced and possibly the molten material is carbonized , from which metal and slag are continuously or occasionally removed from the reactor chamber ·

If a cheap heat source is available, the solid metal or substantially metallic material may be preheated before being introduced into the reactor chamber, and said material may also be fed together with slag to refine the molten metal melt * In this case, it is possible to keep a layer of molten slag and heat can also be developed inductively in slag melt. Coke substrate coke is replaced as it is used, almost continuously, so that the coke to be replaced is formed by replacing the coal and coking it in the reactor chamber as described above *

Hydrocarbons can also be introduced into the reactor chamber, partly as fuel to generate some of the heat required in the process, partly to improve the quality of the coke formed from the coal as described above * Heat generated during combustion of combustible materials in the reactor chamber, not consumed in the reactor chamber, can be recovered associated with a steam boiler installed in connection with the reactor, and at least a portion of the heat content of the gases formed in the reactor chamber can be utilized to generate electrical energy or steam.

The invention can also advantageously be applied in connection with the treatment of metal oxide melts. Thus, the invention can be advantageously applied, for example, when at least one metal, e.g. iron or silicon, is produced from a melt containing said metal as an oxide, e.g. slag, and said melt is fed to a coke substrate and the residence time of the melt on the coke substrate is adjusted so as to reduce using a continuous test bed and obtained in molten form from the area below the coke bed and the metal and the newly formed and possibly remaining slag are continuously or intermittently removed from the reactor chamber. The test substrate then forms a very large hot contact surface, which is reducing, Λ · 9 62232 f for the metal oxide melt, so that high power is obtained from the reactor. The metal melt and slag melt can each be removed separately from the reactor. Especially in the case that the slag melt has a refining effect, which is obtained, for example, by adding suitable refining agents, it is advantageous to keep a layer of molten slag under the coke base, so that part of the heat required in the melting process can be generated inductively in the slag melt.

The coke consumed in the coke substrate is preferably replaced almost continuously, which can take place by adding carbon and coking it in the reactor chamber section. In this case, coking «as well as the storage of excess heat generated by the combustion of combustible substances in the reactor chamber can take place as described above with reference to other embodiments of the process according to the invention.

Due to the large contact surface formed by the heated coke substrate according to the invention, the process according to the invention can also be advantageously applied to the production of a relatively volatile metal such as zinc, lead, arsenic, antimony, cadmium and tin, or a metal compound containing at least one of the above metals. contains said metals in the form of an oxide and / or sulphide, for example from slag such as slag obtained by smelting copper ore and thereby allowing the melt to pass through an inductively heated coke substrate and its residence time on the coke substrate The vaporized metal or metal compound can be oxidized by burning combustible substances oxidatively in the reactor chamber, and the metal is then obtained in oxide form from the combustion shafts outside the reactor. The vaporized metal or metal compound can also be discharged from the reactor chamber and recovered in solid or liquid form outside the reactor chamber by condensation. If. moreover, the melt contains at least one oxide-bound, relatively difficult-to-evaporate metal, such as iron and silicon, this metal can be obtained simultaneously as described above, which is used to reduce at least one metal from a melt containing said metal as oxide-bound. To replace the coke consumed in the coke substrate, coke may be imported or prepared as described above with reference to other embodiments of the process. The same applies to discharging the metal slurry and slag from the reactor chamber and introducing additional heat 62232 10 into the reactor chamber and the charge therein, and recovering unused heat from the gases or gas-forming substances formed by reduction in the reactor chamber and introduced into the reaction chamber.

In reactors of the type in question, electrical insulation between the windings and, in some cases, between the sub-windings can cause certain problems if there is some gas permeation in the reactor walls. In some cases, e.g. proven that carbon dioxide-containing gas can penetrate out of the charge through the reactor walls and cause carbon to precipitate, which can result in a spark discharge in the coil. These problems are exacerbated in the construction of very large, inductively heated reactors and furnaces, which require the use of voltages not previously used in induction heating technology. The problem becomes particularly serious because the repair of a coil made according to the current technology often results in expensive, complete disassembly, which would have very difficult technical and economic consequences for the method in question.

Surprisingly, however, it seems possible to prevent spark discharges in the induction coil in advance when the process according to the invention is carried out in a reactor equipped with a wall member separating the induction coil from the reactor chamber and passing some gases through a gas whose pressure exceeds the highest the pressure in the area of the reactor chamber, and this gas cannot cause conduction of electricity between the windings.

A suitable procedure in this case may be to prevent the flow of pressurized gas to said wall member away from the reactor chamber. This can take place, for example, by keeping at least the part of the reactor covered by the induction coil closed in the pressure chamber. In this case, the gas under pressure can be led to the wall member via a pressure chamber. According to another example, in this procedure, the areas between adjacent winding threads which are against the atmosphere surrounding the reactor can be sealed and the pressurized gas is introduced inside these gas-tight areas.

However, the risk of a spark being released between the turns of the induction coil cannot be completely eliminated. Therefore, it has proven advantageous to combine the above-described procedure with measures which make it possible to repair the parts of the induction coil without having to completely disassemble the reactor. This can be done by using induction coils made of several elements rotating up to 160 °.

It may often also be advantageous to use induction coils assembled from several sub-coils. In addition, each winding thread can be placed in one plane. Thus, separate single-thread loops are obtained which can be joined together into sub-windings with an arbitrary number of turns.

This arrangement has the following advantages: special sealing between the winding threads is structurally simple to perform using a gas conduction to a wall member as described above, offers the best conceivable number of sub-windings to the electrical quality of the heated substance, simplifies winding distribution and during which the reactor remains gas-tight.

A further advantage of single-winding loops in one plane is that the joining of turns into sub-windings with an arbitrary number of turns can be performed so that the voltage between the adjacent turns of two sub-windings is 0. This is possible if the adjacent sub-windings are given a different winding direction and at the same time the ends near the adjacent sub-windings are connected to the same point in the power supply system. This arrangement avoids that the gap between the two sub-windings is loaded with the high voltage corresponding to the voltage between the turns of the sub-winding layered by the number of turns of it.

The pressurized gas as described above flows through the gas permeable wall member to a space where the material to be heated is.

It is therefore important to choose a gas whose assembly is safe for the heating process. In cases where there is a risk of carbon depositing on the wall member, it may be advantageous to use a substantially inert gas with an oxygen or hydrogen potential such that carbon deposition is prevented at least in the parts of the wall member adjacent to the induction coil.

The invention will now be described with reference to the accompanying drawings, - 3 "'\ 5 :; . 'j,.

62232 12 which show the features and advantages of the invention. The drawings show, in schematic vertical sections, a number of sketches of various embodiments of the method according to the invention. Figure 1 shows the installation of a carbon experience according to the invention. Figure 2 shows an installation for the reduction and / or roughening of gaseous media according to the invention. Figure 3 shows an apparatus according to the invention for the reduction and subsequent carbonization of a solid metal oxide-containing material. Figure 4 shows an apparatus for smelting scrap according to the invention. Figure 3 shows an apparatus for treating melts *, in particular slag melts, in accordance with the invention. Figures 6-9 show a vertical section of a part of a reactor wall with four different devices for preventing spark discharge in an induction coil. Figure 10 shows a part of the horizontal projection of the induction coil, the coil being constructed of several elements with a small angle of rotation. Fig. 11 shows a part of a perspective view with an induction coil formed substantially according to Figs. 9 and 10. Fig. 12 is a sectional side view showing two sub-windings constructed of in-plane windings that receive current as shown.

In the different figures, corresponding or substantially similar details are given the same reference numerals.

Figure 1 shows a coking reactor whose walls at least partially consist of a refractory liner 10 and a jacket 11, which is, for example, a steel plate. An induction coil 12 is mounted around the reactor, in which an alternating current from a power source not shown in the figure flows, with external frames 13, and the purpose of the coil is to keep the substrate 14 in the reactor chamber, substantially coke, at a temperature suitable for the process.

The reactor according to Figure 1 comprises a bottom-open, bellows-dependent upper part 16, a rotating part 17 and a stationary base 18. The lower part 17 «, which is connected to the upper part 16 via a water trap 19, is supported by a number of support and support rollers cooperating with an annular flange 20. , 22. The part 17 consists mainly of a cooling jacket 23 «in which liquid flows, the outer surface of the jacket has a gear ring 24 and the part rotates by means of a motor-driven gear 23 which engages the gear ring. The part 17 is provided on the inside with some discharge buckets 26 which, as the part 17 rotates, remove the coked material between the part 17 and the base 18. The base 18 is cup-shaped and forms with the lowest part of the part 17 a water trap 27 · * t \, f * 15 62232

When coking coal in the reactor of Figure 1, carbon is introduced into the reactor chamber from openings 28 above the induction coil 12 and sinks down by the buckets 26 of the reaction chamber, past the level of the coil 12 where it is heated to the coking temperature and forms an inductively heated substrate 14. level, it has already been coking under the influence of, for example, the conductive and radiant heat of the substrate 14. Before the coke leaves the reactor, it cools in the liquid lock 27 and is also cooled by the cooling jacket 25.

Carbon is introduced into the reactor chamber almost continuously. In the example shown, some so-called stoukers, each with a funnel 29, the outlet of which opens into a line 30, which in turn opens at 28 into the reactor chamber. At the end of the line 30 away from the reactor chamber, there is a pressure cylinder 31 which supplies the carbon from the hopper 29 to the line 30 and from there to the reactor chamber. Figure 1 shows only one stouker and a landing opening 28 from another stouker ·

The coking reactor has lower and upper discharge lines 32 and 33 »which can be used either separately or simultaneously to remove the gas formed in the coking from the reactor. The lower discharge line 52 is connected to the reactor chamber at a point below the induction coil 12 through an annular channel 34 and a plurality of openings 33. Above the coil 12 there are a plurality of wires 37 »opening at 36, from which a predominantly liquid hydrocarbon can be passed over the coking coal. A number of burners 3® are installed in the space above the charge, with a line 39 for conducting fuel and a line 40 through which an oxygen-containing gas, such as air, is passed. Only one of the burners is shown in Fig. 1, 3® »and the combustion gases coming from it into the furnace chamber through the openings 41, which are directed so that a vortex movement is generated in the space above the charge. Possibly only air or other oxygen-containing gas is passed above the charge to burn the gases produced during coking.

When only the upper outlet line 33 is used, i.e. the outlet line 32 is closed by a valve device not shown in the figure, the gases formed in the coking of the coal in the reactor chamber pass upwards through the reactor chamber and out through the outlet line 33. In order to preheat the coal and start coking, the coke gases formed in the coking, rising through the charge and M · * ► itr. ...

14 62232 Hydrocarbons possibly added via lines 37 above the charge by means of burners 38 · The gases leaving the outlet line 35 are suitably recovered, for example, for the production of steam or electrical energy.

When only the lower outlet line 32 is used, the outlet line 33 is kept closed by means of a valve device, which is not shown in the figure, and the gases formed from the coke pass through the openings 33 and through the annular channel 34 and the outlet line 32 from the reactor chamber. It is possible that the burners 38 are used to maintain reducing combustion above the charge, so that part of the energy required in the coking process is obtained.

Hydrocarbons are passed through lines 37 which, as they pass by a substrate 14 at a temperature higher than that required for hydrocarbon cracking, crack and cause carbon to precipitate on the formed coke, the quality of which is greatly improved.

The gases leaving the outlet line 32, which contain a large amount of combustible gases, can advantageously be combusted to generate electrical energy for the inductive heating of the coke substrate 14 itself. According to the cooked embodiment, the physical heat content of the gases leaving line 32 is recovered by means of an indirect heat exchanger 42 »

Alternatively, the gas is passed through both lines 32 and 35, whereby oxidative combustion can be advantageously maintained in the furnace chamber on the charge and it is ensured that all oxidizing gases are removed via line 33 and only part of the coke oven and some of the hydrocarbons from line 37 are cracked. through the discharge line 32.

In Fig. 2, reference numerals 10 to 14 »52, 54, 55 and 42 are the same as in Fig. 1. In the reactor shown in Fig. 2 for reducing and / or carbonizing gaseous media so that they come into contact with the inductively heated coke support 14, such a high temperature in the reactor chamber so that the residues of coke used in the process are obtained in the molten state from the bottom of the reactor. The molten coke residue 45 is removed continuously or, as shown in the figure, from time to time through the discharge hole 44 and the chute 43. A gaseous medium, for example water vapor to be reduced and / or carburized, is introduced via line 46 after it has received heat in the indirect heat exchanger 42 from the reduced, reduced and / or carburized gas leaving the reactor line 32 and exits through openings 35, directed obliquely downwards to prevent coke from entering the annular channel 34 and clogging. Coke, or alternatively carbon, which coke as it travels toward the plane of the coil 12 within the reactor chamber, is fed to the reactor chamber through a feeder 47 so that the coke used in the substrate 14 is replaced.

If the material fed from the feeder 47 is carbon, it coke as it travels toward the plane of the coil 12, whereby the coke gases, after being cracked in the substrate 14, exit together with the reduced and / or carburized gaseous medium through line 32. If the carbon is of poor quality, it is preferable to conduct so much hydrocarbon through line 43 and maintain such conditions in the furnace that the hydrocarbon, when cracked, causes carbon to precipitate on the newly formed test, thereby significantly improving its mechanical strength.

Figure 3 shows a reactor for the reduction and melting of iron oxide powder. For the purpose of symbols 10 to 14, 37 to 41 to 44, 45 and 47, reference is made to the description of Figures 1 and 2. The upper part of the reactor is formed as a radiating part in a steam pan associated with the reactor, which is not otherwise shown in the figure. Thus, the upper part of the reactor chamber is surrounded by a double jacket 49 in which water or steam circulates, which in turn is surrounded by a thermally insulated jacket 50. The material supply line 31 extending downwards from the feeder 47 is double-walled and flows in a jacket 49. In the region of the coil 12, the reactor wall is cooled by a cooling jacket 32.

Via line 31, a material consisting of iron oxide, coke or alternatively carbon, which is coke as described above in the reactor chamber, and possibly a slag-donating substance, is introduced onto the substrate consisting essentially of coke. Liquid or gaseous hydrocarbons can be added to the charged material via line 37, which material is preheated by burners 38.

Thus, the preheated iron oxide material is pregelatinized and metallized to some extent above the coke substrate and melted together with the slag-forming material at the top of the induction zone, after which the iron oxide is -sale carbon. The molten material is obtained from under the substrate as a slag layer 33 and a carbonaceous iron layer 34 * Iron can be removed from time to time from the outlet 44 * Slag is suitably removed, mainly continuously, from the outlet 35 and the chute 36. The outlet is equipped for this purpose r * - '· *' 16 62232 provided with a movable, actuator-movable stop 57 * which is controlled so that the boundary between the substrate 14 and the slag layer 55 is maintained at the desired level in the reactor chamber. The carbonaceous gas formed in the reduction, as well as the residual hydrocarbon possibly passed through line 57 and any coke gases, are burned by burners 58 on the material charged to the reactor. In addition, the reactor according to Figure 5 can be used advantageously for the final reduction and smelting of pre-reduced iron oxide, for example iron sponge. The reactor according to Figure 5 can also be used for the reduction and possibly carburization of other solid metal oxide-containing material, for example for the production of molten calcium carbide, in which case calcium oxide and carbonaceous material are introduced through line 51.

Figure 4 », in which the symbols 10 - 14 * 28 - 31» 44 * 45 and 52 - 57 mean the same as in Examples 1-5, shows a reactor by means of which a metallic material, in whole or in part, in the form of a piece, in particular cheap scrap metal, can be melted, such as lathe chips and the like. The scrap is introduced together with the coke or coal and possibly also the slag-forming agent by means of stoukers 50, 31 to the inductively heated coke substrate 14 «On the substrate 14 and in the substrate itself the scrap melts both inductively and in contact with the hot coke substrate, the refined scrap material is obtained as a molten layer 53 and 54 below the substrate 14. The gas formed exits via line 58. If carbon is introduced into the reactor chamber, care shall be taken to coke it at least substantially before it enters the substrate. 14 * Liquid or gaseous hydrocarbons may, if desired, be added to the batch material and preheated in the reactor chamber by burning combustible materials as described above. 1-3 context. The boundary between the slag bath 53 and the coke tray 14 is maintained at the desired height level by removing the slag through the outlet 55, respectively.

Figure 5 *, in which the symbols 10, 12 to 14, 44, 45, 47, 49 to 52 and 55 to 57 have the same meaning as in Figures 1 to 4, shows a reactor capable of producing at least one relatively volatile metal or metal compound, and at least one relatively difficult-to-evaporate metal, for example from a slag melt. In the reactor, the coke base 14 * is maintained in the plane of the coil 12 to which the slag melt is introduced continuously or in portions. In the embodiment shown here, the slag melt is introduced from the ladle 59 into a chute 60, 17 62232 from which the melt is distributed to the substrate 14 via a plurality of distribution tubes 61 entering the reactor chamber. The substrate temperature is kept so high that volatile metal or metal compound, e.g. exits the reactor chamber after it has first been optionally combusted by means of oxygen-containing gas introduced through the inlet lines 62, for example air. The slag residue passes down through the coke substrate 14, where a volatile metal oxide, such as iron oxide, is reduced and carbonized upon contact with the substrate and continuous consumption. The substrate 14 is replaced by introducing new substrate material at the same rate as it is consumed, optionally with the addition of suitable slag-forming agents, through the feed pipe 31. The fully reduced metal is obtained as a molten lower layer 63 at the bottom of the reactor, while the residue of the introduced and formed slag is obtained as a slag layer 64 above the layer 63. The boundary between the slag layer 64 and the coke substrate 14 is maintained at the desired height by continuously or occasionally removing slag from layer 64.

Figure 6 shows a part of the reactor wall with a ceramic liner 10 and a jacket 11. The number 12 denotes an induction coil mounted outside the liner 10, which consists of a tube which can be cooled by passing coolant through it. The coil 12 is partially covered inside the ceramic filling mass 63. Both the liner 10 and the filler 63 are gas permeable, if any.

In order to prevent solid, liquid or gaseous materials from entering the coil 12 from the opposite side of the coil to the reactor wall, i.e. from the reactor chamber into which the material to be heated is taken, a pressure in the wall member 10, 63 at the height of the coil 12 is maintained by means of a gas which exceeds the highest pressure prevailing in the region of the induction coil in the reactor chamber. The gas used is selected so as not to be able to cause electrical conduction between the turns of the coil 12. Said pressure is maintained by passing a pressurized gas, for example air or a substantially inert gas, through a conduit 66 to a pressure chamber 67 which seals the induction coil 12 against the surrounding atmosphere.

Figure 7 also shows a part of the reactor wall provided with a liner 10, a filling mass 63 and an induction coil 12. The gaps between adjacent windings are sealed against the atmosphere surrounding the reactor by means of a suitable insulating material 6θ. The sealing device 68 has a plurality of cavities 69 through which the pressurized gas, as indicated by the arrows, is directed to those parts of the reactor wall 10, 63 which are at the forefront of the coil 12.

16 62232

Fig. 8 shows an embodiment which in principle corresponds to the embodiment of Fig. 7. The reactor wall formed by the liner 10 and the packing mass 65 is surrounded by a helically wound induction coil 12. The sealing of adjacent coil threads is likewise provided by helical hoses or the like 70 which are of resilient material. In order to make the contact surfaces small and thus more effectively sealed between the hose 70 and the coil 12, a pipe 71 with a small diameter is welded over the latter. At the same time, the hose 70 is also used to lead the pressurized gas to the wall member 10, 65 and is therefore partly connected to a pressure source not shown in the figure, partly provided with degassing openings directed towards the reactor wall.

Figure 9 also shows the part of the reactor wall consisting of the liner 10 and the filling mass 65 and surrounded by the induction coil 12. Each coil of the winding is trapezoidal in cross-section and provided with flanges 73 above and below. * Between the flanges near the adjacent winding coils there is a seal 74 of resilient material, the seals have holes 75 from which pressurized gas can be filled in the seal 74 between the coil layers «Gas is introduced into these holes 75 through the distribution pipes 76 which leave a common inlet pipe 77 for a number of distribution pipes 76 ·

Figure 10 illustrates how each of the winding turns of the coil 12 may be constructed of a plurality of elements 78 a to d, preferably placed in the same plane, each of which rotates at an angle of less than 180 °. Numeral 79 denotes lines through which coolant and possibly also current can be conducted between adjacent elements 78a-d, and numeral 80 denotes sealing devices which seal the adjacent ends of the elements 78.

Figure 11 shows in more detail the junction of the adjacent elements 78a and 78b of the two patterns 10; the shape of the elements is substantially the same as in Figure 9 * of the second element 78a of the flanges 73 run at a distance from the downstream end, while the other elements 78b of the element 78a over the extending flange 81. The seal between adjacent elements of the ends takes place in the compression flange 81 of the inner side of the element 78a between the outer side of the seal 82, which is somewhat flexible in the longitudinal direction between the elements 78a and 78b.

Figure 12 shows an induction coil constructed of two sub-windings, each consisting of three windings 85-85 and 62232 19 86-88. Each winding is in the same plane and may be formed of elements as shown in Figure 10. There are seals 89 between the intersecting ends of each winding turn and between adjacent winding turns. between each sub-winding through the contact members 95 -98. As can be seen from the figure, the sub-windings 83 to 85 and 86 to 88 have different winding directions and the adjacent ends of the sub-windings are connected in principle to the same point in the power supply system, as a result of which the voltage between windings 85 and 86 is always zero.

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

Example 1

A coke substrate having a resistivity of 10 μm and a perasability of about 4 <3f · 10 μm / h and a diameter of 7.0 m and a height of about 5 m was maintained at a temperature of about 1000 ° C in a reactor such as that shown in Fig. 1. About 74.9 tons / day of coke was continuously removed from the bottom of the substrate while the substrate was continuously replenished by adding carbon to the substrate. Carbon containing 29% by weight of volatile components (based on combustible material) and 12% by weight of ash was added at about 100 tons / day and coke in the reactor to remove gases. Energy of 110 MWh / day was applied to the coke substrate electrically inductively, with a current frequency of 100 Hz, by means of an induction coil surrounding the reactor at the level of the coke substrate with a diameter of 7.9 n and a height of 4.9 m. The said energy was sufficient to maintain the substrate temperature and carbon coking. . The amount of gas formed increased to about 60,000 Women per day and consisted mainly of hydrogen and hydrocarbons.

Example 2

A gas consisting essentially of 20% by volume of CO 2, with the remainder being CO 2 and H 2 S, was continuously passed through a reactor of the type shown in Figure 2 and containing an electrically inductively heated coke oven medium as in Example 1. to a temperature of about 800 ° C: The reduced gas leaving the reactor and passing through the medium contained CO and H 2 and hydrocarbons and rose to about 283,000 Nm / day. Energy of 100 MWh / day was applied to the coke substrate electrically inductively, current frequency 100 Hz, by means of an induction coil as in Example 1. To replace the used coke 20 62232, about 35 tons / day of carbon as in Example 1 was introduced into the coke substrate and about 4 tons were withdrawn from the reactor. ash.

Example 3

The electrically inductively heated coke substrate of Example 1 maintained in a reactor of the type shown in Figure 3 at a temperature of about 1500 ° C was continuously fed with pre-reduced iron oxide having a composition substantially corresponding to FeO of 72 tons / day together with carbon identical to Example 1. has been reported and was 19 tonnes / day. 55 tonnes / day of molten pig iron with a carbon content of about 4% by weight was removed from the bottom of the reactor, together with molten slag of about 6 tonnes / day. At the top of the reactor, gas containing mainly hydrocarbons and carbon monoxide was removed in an amount of about 30,000 NmV / day. To obtain the energy needed to maintain the substrate temperature and perform the reduction, 90 MWh / day was introduced into the coke substrate by means of an induction coil as in Example 1 with a current frequency of 100 Hz.

Example 4

The iron oxide material was reduced as described in Example 3, with the exception that the oil was burned at 20 tons / day in a reactor above the substrate. The need for electricity thus decreased to 70 MWh / day for the same amount of pig iron produced, while at the same time the amount of gas leaving the reactor increased to about 215,000 Nm 2 / day. Said gas consisted mainly of CO 2 and H 2 O.

Example 5

An electrically inductively heated coke substrate such as Example 1, maintained in a reactor of the type shown in Figure 4 at a temperature of about 1500 ° C, was fed almost continuously with scrap iron containing 90% by weight of metallic iron, about 200 tons / day together with carbon similar to Example 1. has been reported, 7 tons / day. About 195 tons / day of molten pig iron and about 0.5 tons / day of slag were emptied from the bottom of the reactor. About 15,000 Nm / day of gas containing mainly carbon monoxide, hydrogen and hydrocarbons was removed from the top of the reactor. The amount of energy required to maintain the substrate temperature and to melt the scrap and reduce its oxidized parts was obtained by introducing 96 MWh / day into the coke substrate as in Example 1 by means of an induction coil at a current frequency of 100 Hz.

Example 6

An electrically inductively heated coke oven substrate such as Example 1, which was maintained in a reactor of the type shown in Figure 3 at a temperature of about 1500 ° C, was continuously fed with molten fayalite slag having a temperature of 1450 ° C and an iron content of about 50% by weight together with limestone , which was about $ 0 ton / day, and carbon similar to that reported in Example 1, about 45 tons / day. Molten pig iron was discharged from the bottom of the reactor at 97 tons / day together with molten slag of about 120 tons / day, the composition of which corresponded mainly to wollastonite. The top of the reactor was degassed with 64,000 Nm 2 / day, consisting mainly of CO 3, CO and Hg. To meet the energy requirement for maintaining the substrate temperature and performing the reactions, 130 KWh / day was applied to the coke substrate by means of an induction coil as in Example 1 at a current frequency of 100 Hz.

Example 7

An electrically inductively heated coke substrate such as Example 1, maintained in a reactor of the type shown in Figure 3 at a temperature of about 1500 ° C, was continuously fed with slag obtained by electric smelting of copper-fine stone; the slag temperature was 1250 ° C and contained 10 wt% Zn, 2 wt% Ph, 45 wt% FeO and the residue was predominantly SiOg. Slag was fed at about 150 tons / day along with coal similar to that used in Example 1, 22 tons / day, and limestone at about 110 tons / day. About 110 tons / day of low carbon molten iron with a silicon content ranging from 2 to 6% by weight and about 75 tons / day of molten slag were removed from the lower end of the reactor; the composition of the slag corresponded mainly to wollastonite. Approximately 54,000 Nm ^ of gas / day was generated on the coke platform. Before this gas, which contained not only Hgita, CO and CO 3 but also 13 tons of Zn and Ph, was discharged from the reactor, air was introduced into it to oxidize the Zn and Ph it contained. The metal oxides thus obtained were separated in the form of fine dust from the rest of the gas by post-treatment in a steam pan and gas purifier.

The invention is not limited to the embodiments described above, in the description of which reference is made to the drawings, but the implementation can be modified in several ways within the scope of the following claims.

Λ · *

Claims (2)

22 62232 A method for electroinductive heating of a particulate material, e.g. coke, in a reactor chamber, comprising a stationary layer having a resistivity J1 greater than metal, wherein the electroinductive heating of the material takes place in the layer itself by means of at least one induction coil with a low frequency and which coil is arranged outside the reactor chamber to surround it coaxially, the axis direction being vertical, characterized in that an alternating current of up to ten times the mains frequency is used in connection with a layer with a resistivity of -4 10 to 10 Am and that the lowest the ratio between the horizontal transverse dimension d and the induction field penetration depth S is kept between 0,2 and 2,5, which is determined by the equation | = k (0.54-0.35.10log ^, where k is a number between 1.1 and 1.5 and S is given by the equation δ. \ / ΐΐ ^ WI where oo is the angular frequency of the electromagnetic field expressed in -1 in s, yu the permeability of the layer expressed in H / m and its resistivity expressed in Am. A method according to claim 1, characterized in that electrically insulating pressurized gas is introduced from the outside to the reactor walls surrounded by the induction coil, which pressure exceeds the highest expected pressure inside the reactor chamber.