Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
  • C10B19/00—Heating of coke ovens by electrical means
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
  • C10B1/00—Retorts
  • C10B1/02—Stationary retorts
  • C10B1/04—Vertical retorts
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
  • C10B53/00—Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form
  • C10B53/08—Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form in the form of briquettes, lumps and the like

Definitions

• the invention relates to a process for the production of molded coke and a shaft furnace for the production of such coke in which the heating and coking heat is supplied by an electrical energy supply and transferred by a recycled gas stream.
• the invention also relates to a method and an electrical heating device using a granulated fluid-conducting bed.
• Processes are known for manufacturing coke molded in a shaft furnace, in which a mass of molded coal balls circulates from top to bottom, against the flow of a recycled gas stream originating from a fraction of the gas produced by the coking and taken from the top of the oven to be reintroduced at the base of the latter.
• the coking of the molded balls takes place in a central zone of the furnace by gaseous contribution from the distillation.
• FR-A-628.168, US-A-2.127.542, DE-A-409.341 and FR-A2.529.220 proposed, to solve these problems, to bring the heat energy of coking directly into the zone concerned, by conduction electric in the solid mass of hot balls, by generating electric currents between diametrically opposite electrodes, separated by the solid mass of coking balls.
• the shaft furnace is in the form of a column with a straight section, substantially uniform over the entire interior height of the bed of circulating molded balls, comprising, on the one hand, electrodes arranged in a median zone of the lateral wall of the furnace, and on the other hand, mobile electrodes, which are introduced by the upper part of the furnace into the bed of circulating balls, and arranged in an adjustable manner at a level of the furnace higher than that of fixed electrodes.
• One of the major drawbacks of this type of oven lies in the difficulty of ensuring an appropriate electrical conduction of the bed of ball of molded coal in circulation, in order to regulate in a homogeneous and optimal way the calorific contribution necessary for the coking of the balls.
• the object of the invention is to remedy these drawbacks by providing a process for the manufacture of coke molded in a vertical tank oven, the structure of which optimizes the distribution of the supply of heat energy suitably distributed over the entire section of the oven, while by ensuring correct circulation of the coke mass and by achieving the optimal conditions for coking the molded coal balls.
• the terminal coking phase is carried out by. dissipation of electrical energy by the Joule effect, in the bed of balls which have become conductive, up to the desired final temperature. Recycled gas, stove fairies by heat exchange during the primary cooling of the balls, are overheated on the electrically heated balls; they successively transport and transfer this heat to the balls during carbonization, distillation and preheating in the upper zones of the oven.
• the electric heating is carried out by electric conduction in the moving bed of coked molded balls of a current generated between at least two diametrically opposed electrodes, placed in the walls of the tank at the level of the second zone. - The electric heating is carried out by induction of electric currents in the moving bed of coked balls which garnish the lower part of the second zone.
• a further subject of the invention is a process for manufacturing metallized molded coke, characterized in that a coke, by a process as defined above, is coked with a charge of molded balls prepared by compacting a paste consisting of a binder, simple or mixed, a mixture of suitable coals, and fine particles of a material based on the metallic element to be incorporated into the coke, in metallic or oxidized form.
• the material based on the metal element consists of iron oxides, manganese ores and dust resulting from the production of ferro-manganese, chromite concentrates for the production of ferro-chromium, quartz fines and of silica powders which must be recycled for the production of ferro-silicon.
• the invention further relates to a tank furnace for the manufacture of molded coke in the form of a substantially tubular enclosure deli using a first preheating zone corresponding to the upper part of the enclosure, a second carbonization and coking zone corresponding to the middle zone of the enclosure and a third coke cooling zone corresponding to the lower part of the enclosure, the oven comprising at its top sealed means for introducing a charge consisting of raw molded balls and means for recovering the gases produced and at its base sealed means for discharging coke and means for admitting a recycled gas stream, the intake means being connected, outside the oven, to the means for recovering the gases produced by recycling means, and electric heating means arranged in the wall of the second carbonization and coking zone , characterized in that the oven comprises a fourth sealed secondary cooling zone connected upstream to the means for evacuating the third zone and in downstream to a leak-proof airlock, the fourth zone comprising at its base at least one supply line for secondary gaseous cooling current connected to the recycling means, and at its top, at least one line for
• the watertight means for introducing the load consist of a sealed load supply airlock opening at its lower part into the first zone of the furnace by a distribution bell, the supply airlock being itself supplied by a rotating hopper.
• the means for evacuating the coke from the third zone comprise a rotating and mobile floor in vertical translation opening out, via a sealed airlock, into the fourth secondary cooling zone.
• the electric heating means are of the conduction type and consist of at least one pair of diametrically opposite electrodes, disposed at the base of the wall of the second zone of the enclosure of the oven, said wall forming, in this zone, a constriction of the internal section of passage of the bed of molded balls delimited by a shoulder against which the fixed electrodes are housed.
• the electrodes consist of segments, the profile of which in vertical section is L-shaped extending along each side of the shoulder so that one of the branches of L is horizontal. In the case of a circular section tank, the electrode segments are circular and separated from the others by an intermediate wall of refractory and insulating material in the form of an inclined plane corresponding to the slope of the shoulder delimited by the L-profile. electrodes.
• This L-shaped profile is preferably chosen because it causes an embankment accumulation of coked and very conductive balls on the electrode which they protect.
• This protective slope is constantly renewed; it extends the electrode while protecting it from abrasion from the descending molded coke bed, and it isolates it from the hot cooking zone and from the gases of the recycled gas stream, very hot at this level. This results in a decrease in heat losses and a better mechanical resistance of the electrodes, especially if they are made of cooled alloy copper.
• the oven comprises an internal enclosure in the shape of a warhead in a refractory material provided with a central electrode cooperating with a peripheral electrode circulating along the internal wall of the enclosure.
• the two electrodes are supplied by a direct or single-phase current source.
• the electric heating means are of the induction type and consist of an induction coil coaxial with the tank and housed in the refractory lining of the furnace.
• the oven comprises an internal enclosure in the form of a warhead made of a refractory material, in which is housed a laminated magnetic core.
• the correct distribution of the heating energy is further improved by winding around this magnetic core an internal induction coil, coaxial with the external induction coil, and supplied in phase with the latter, by the same current source at medium frequency.
• the induction heating means consist of a set of pairs of induction coils arranged radially in the refractory wall of the furnace, defining an external inductor generating a rotating field passing horizontally through the tank.
• the oven has an internal enclosure in the shape of a warhead made of material. refractory in which is housed an internal inductor consisting of a set of radial coils arranged opposite the coils of the external inductor and determining a set of pairs of coupled coils which cooperate to generate a rotating field between the external inductor and the internal inductor.
• the electric heating means consist of the combination of at least one pair of electrodes as described above generating conduction heating, and at least one coil generating induction heating .
• Fig. 1 is a schematic view in axial section of a circular coking oven according to the present invention.
• Fig. 2A is a view in horizontal section along the plane 2-2 of FIG. 1 of a first variant, with two pairs of electrodes supplied by a two-phase current source (Scott transformer).
• Fig. 2B is a block diagram of the supply of the electrodes of FIG. 2A.
• Fig. 3A is a view in horizontal section along the plane 2-2 of FIG. 1 of a second variant with three pairs of electrodes supplied by a three-phase current source.
• Fig. 3B is a block diagram of the supply of the electrodes of FIG. 3A.
• Fig. 4 is a view in vertical radial section along line 4-4 of FIG. 3A from the oven wall in the area of an electrode.
• Fig. 5 is a view in radial and vertical section along line 5-5 of FIG. 3A from the oven wall.
• Fig. 6 is a perspective view of a battery with three coke oven units according to the invention in a variant with rectangular cross section, with three pairs of opposite electrodes supplied with three-phase current.
• Fig. 7 is a partial view, in axial section, of the lower part of a variant of the oven of FIG. 1, with a single-phase or direct current supply.
• Fig. 8 is a view in horizontal section along the plane 8-8 of the oven of FIG. 7.
• Fig. 9 is a partial schematic view in vertical axial section of a second embodiment of the oven according to the invention, heated by simple induction.
• Fig. 10 is a partial schematic view in vertical axial section of a second variant of the oven according to FIG. 9, with external and axial induction heating.
• Fig. 11 is a partial schematic view in vertical axial section of a third variant of the oven according to FIG. 9 with external induction heating of rotating fields.
• Fig. 12 is a partial schematic view in vertical axial section of a fourth variant of the furnace according to FIG. 9, with external and internal induction heating of rotating fields.
• Fig. 13 is a schematic view in horizontal section along the plane 13-13 of the oven according to FIG. 12 illustrating the principle of connection of the inductors.
• Fig. 14 is a partial schematic view of a mixed embodiment of the invention, with heating by single-phase conduction and by external induction.
• the process of the invention consists in coking, continuously, in an electrically heated tank furnace, by conductor and / or by induction, balls of dried coal agglomerated by binders and molded in press.
• the pyrolysis of the balls in the furnace causes the emission of distillation gases from the coals and the binders, a large part of which is recycled at the base of the furnace, after brief purification. These recycled gases form an ascending gas stream which cools the balls in the lower part of the furnace and the gradual heating, in counter-current, of the balls which descend the upper part of the furnace.
• the balls are successively preheated and dried, then smoked.
• the carbonization then ensures the mechanical consolidation of the balls.
• the progressive heating of the balls completely eliminates the volatile matter around 850oC and the balls then become conductors of electricity.
• This conductivity is used to pass electric currents through the ball bed which cause the balls to be heated by the Joule effect in their mass and at the points of contact between them. This electric heating completes the cooking and coking of the balls at the desired temperature.
• the ball of balls then behaves like a heating grid which overheats against the current the ascending gas flow coming from the lower part of the oven in which the coked balls are cooled. This overheating of the gas also has the effect of cracking the heavy hydrocarbons still contained in the gas.
• the ascending gas stream then essentially consists of hydrogen (and methane). By its particular thermal and electrical properties, it constitutes an excellent vector of heat exchange between the gases and the balls, which avoids the formation of arcs and discharges between the balls.
• the raw molded balls are prepared by first making a paste by kneading with a mixed binder (pitch, tar, asphalt %) of coals previously mixed, dried, ground and preheated.
• a mixed binder pitch, tar, asphalt
• the preheated dough is then compacted into balls in a tangential cylindrical hoop press.
• the shaft furnace shown in FIG. 1 comprises a metal casing or shielding 1 provided on its internal face with a refractory lining 2 delimiting a substantially tubular enclosure 3, and slightly frustoconical in its upper part, in which is loaded a mass of molded balls constituting the moving bed 4.
• the enclosure 3 is of circular section, but may also have a rectangular section as illustrated in FIG. 6.
• the shaft furnace is loaded at its top by watertight means for introducing the raw molded balls, which comprise a rotary hopper 5 supplied with balls by a belt conveyor 6 controlled by a charge level detector 7 placed in the hopper.
• the hopper 5 has at its lower part a rotating bell 8 whose opening, under the action of a jack 9, frees the introduction of the balls into a sealed lock airlock 10 comprising pipes 11a, 11b of purging with a neutral gas.
• the airlock 10 is closed at its lower part opening into the oven, by a distribution bell 12 whose opening is controlled by a jack 13 according to the indications of a charge level detector 14 placed at the head of the tank. .
• the bells 12 and 8 are opened in sequence according to the indications of the sensor 14.
• the furnace is also provided at its top with means for recovering the gases produced which are constituted by two pipes 15a, 15b, of large diameter, opening into the enclosure of the furnace on either side of the rotating distribution bell 12.
• the coke oven gas recovered via the lines 15a, 15b is sent to a primary purification installation shown diagrammatically at 16 to undergo a treatment of cooling, washing, taring and summary condensation of the water and the naphthalene.
• the gas thus treated is recycled for a fraction of 60 to 80% to the oven by a recycling line 17 and sent for the remaining fraction by a line 18 to a storage gasometer not shown via a conventional secondary purification installation shown diagrammatically in 19.
• the enclosure 3 of the oven has three separate functional areas. The upper part of the enclosure corresponds to a first cooking zone 20 where the balls are progressively preheated, smoked by distillation of the coals and binders and undergo a first phase of carbonization, by the current of ascending hot gases flowing in countercurrent.
• the middle part corresponds to a second zone 21 at the end of carbonization and coking at the base of which are installed the electric heating means 22, housed in the internal wall of the refractory lining 2.
• a third zone 23 for primary cooling of the coke formed occupies the lower part of the enclosure and comprises at its base means for admitting a recycled gas stream coming from the primary purification installation 16.
• These means comprise a set pipes 24 for admission of the primary recycled current from a supply circular 25, itself connected to the recycling pipe 17 by a pipe 26 on which is mounted a valve 27 for adjusting the flow rate controlled as a function of the indications supplied by temperature sensors 28 located at the head of the oven.
• the circulation of the recycled gas in the line 17 is ensured by a fan 29 and the admission flow rate of a first part of the recycled gases, corresponding to the primary current, sent in the line 26 is adjusted to maintain the temperature detected by the sensors 28 at a predetermined set point, to avoid condensation of the tars on the baked balls and on the internal walls of the oven.
• the oven comprises at its base means for evacuating coke from the third zone 23 which comprise a rotary hearth 30 driven in rotation by a geared motor group 31 and movable in vertical translation by means of a height adjustment cylinder 32
• the rotary hearth 30 puts the third zone 23 of the oven in communication with an airlock 33 opening itself into a fourth zone 34 for secondary cooling of the coke.
• the fourth secondary cooling zone 34 has at its base inlet pipes 35 for a secondary cooling current corresponding to the remaining part of the recycled gas stream. These pipes 35 come from a circular 36 connected by a pipe 37, via a flow control valve 38, to the recycling pipe 17.
• the valve 38 is controlled according to the indications provided by a temperature sensor 39 measuring the average temperature of the coke present in the fourth zone 34 for secondary cooling of the coke.
• the flow rate of the remaining part of the recycled gases introduced in the form of a secondary cooling stream is adjusted to maintain the temperature of the coke detected by the sensor 39 at a predetermined set point, lower than the maximum normal handling temperature of the coke. .
• This fourth secondary cooling zone 34 has, at its upper part, conduits 40 opening into a circular 41 collecting the secondary cooling current, itself connected by a conduit 42, on which a fan 43 is mounted, to a return circular 44 of the secondary cooling current surrounding the upper part of the furnace where the recovery of the produced gases takes place and opening into it by return pipes 45.
• the fourth cooling zone 34 is connected, downstream, to a sealed lock airlock 46 provided with purge lines 47, 48 and itself connected to an evacuation hopper 49 releasing the cold coke on a strip dosing extractor 50.
• valves 51, 52 and 53 for communication between the airlock 33, the fourth zone 34 and the sealed lock airlock 46 is controlled respectively by jacks 54, 55 and 56 according to the indications provided by a charge level detector 57 located at the head of the fourth zone.
• the balls leaving the first zone reach a temperature of around 850oC, from which the electrical conductivity becomes appreciable and increases considerably to cap around 1100oC.
• the coke balls descend into the lower part of the furnace corresponding to the third primary cooling zone 23, at the base of which is injected the stream of recycled cold gas which is used as a heat transfer vector in the various zones of the furnace.
• the coke balls continuously extracted from the third zone by means of a rotating hearth are evacuated in two stages.
• the balls are completely cooled by a secondary stream of recycled gas, which is then returned to the top of the furnace: then, they are discharged through the final lock airlock, purged with neutral gas , which eliminates any risk of explosion.
• the molded coke is extracted cold and then screened before shipment.
• the manufacture of electric molded coke Compared to the coke produced in a battery of conventional ovens, the manufacture of electric molded coke combines the advantages of gas coke with those of the electric process. First of all, compared to conventional coke, the manufacture of molded coke has the following advantages:
• the process makes it possible to produce molded coke with smaller units, adapted to the needs in quantity and quality (shapes, dimensions, cooking temperature and reactivity of the coke). - The reduction in investment costs of more than 20%, for the same production.
• electric molded coke has the following advantages:
• the homogeneity of the cooking temperature ensures the regularity of the coke quality.
• the cooking temperature control makes it possible to control the reactivity of the coke produced: reactive coke for electrometallurgy (cooked at low temperature), foundry coke with very low reactivity (cooked at high temperature: 1300oC), blast coke with adjusted reactivity .
• the choice of coke size is possible.
• the low inertia of the oven The low inertia of the oven.
• the rapid electrical control of the heating allows adaptation to changes in pace, corrections to malfunctions (cooking) and facilitates stops and starts.
• the balls are extracted dry.
• the oven is sealed against loading and unloading. Air pollution is therefore limited and working conditions are therefore considerably better.
• the heating means 22 arranged in the lower part of the second zone 21 correspond to two embodiments which will be described below.
• the internal wall of the refractory lining 2 delimiting the enclosure 3, forms a narrowing of the inner section for passage of the bed of molded balls at the lower part of the second zone 21.
• This narrowing is delimited by a shoulder 58 formed along the wall of the enclosure 3.
• electrodes 59 having an L-shaped profile in vertical section extend along each side of the shoulder 58 so that one of the branches of L is horizontal.
• the electrode 59 is made of an electrically conductive material, for example copper and fixed by a tie rod 60 which passes through it, as well as the refractory lining 2, outside the shield 1 by conventional means such as nut and against nut.
• the tie rod 60 is electrically isolated from the shield 1 by the interposition of an electrical insulating material in the form of discs 61.
• the end of the tie rod 60 outside the shield forms a terminal 62 on which is fixed an electric power cable 63 of the electrode connected to the current source 64, shown in FIG. 1.
• the area of the refractory lining 2 immediately adjacent to the electrode 59 is cooled by a tube 65 of internal circulation of cooling fluid disposed in a serpentine fashion along the two faces of the electrode 59 facing the refractory lining.
• the electrode can also be cooled directly by internal circulation of the cooling fluid.
• the electrodes 59 are in the form of diametrically opposite circular segments and separated from each other by an intermediate wall 66 of separation more clearly visible in FIG. 5.
• This wall 66 is in the form of an inclined plane at an inclination corresponding to the slope of the shoulder 58 against which the electrodes 59 are housed.
• a pair of electrodes 59 are arranged around the tank per phase.
• the electrodes of the same phase are diametrically opposite in the tank, as shown in Figs. 2A and 3A, so as to ensure the passage of current to the center of the furnace.
• Their supply voltage is adjustable (phase by phase) by acting on the secondary of the supply transformer.
• a two-phase supply is produced, as illustrated in FIGS. 2A and 28, using a SCOTT transformer, according to the connection diagram in Fig. 2A, which transforms a three-phase primary supply into a two-phase secondary (phases marked 1 and 1b on the one hand and 2 and 2b on the other hand) of adjustable voltage.
• the electrodes 59 made up of circular segments, the section of which is L-shaped, rest inside the furnace on a cooled refractory edge 67 (FIG. 4). There is formed on each of these electrodes, a natural embankment of highly graphitized balls (by local over-coking caused by the prolonged residence time of the balls at high temperature) and very conductive, which protect the electrodes 59 and distribute the current densities in the ascending load.
• Each electrode is separated from its neighbor by the insulating refractory, insulating, abrasion-resistant wall 66 (for example made of silicon carbide bricks, linked to silicon nitride) whose conicity ensures a slight progressive compression of the charge at right copper electrodes in order to improve and homogenize the electrical conductivity of the ball bed during coking.
• the insulating refractory, insulating, abrasion-resistant wall 66 for example made of silicon carbide bricks, linked to silicon nitride
• the developed width of the circular segments of the electrodes 59 is chosen to be approximately equal to the width of the refractory intermediate walls 66 so as to avoid preferential passages between phases or even short circuits from one phase to another on the periphery of the furnace.
• Fig. 6 is shown a variant in which the section of the tank is rectangular.
• This oven is substantially similar to that described with reference to FIG. 1 with regard to the means for introducing the charge of raw molded balls and recovery of coke, as well as with regard to the recycling of coke oven gas recovered by two collecting pipes 70 and 71 located at the head of the furnace and returned to the base of the primary cooling zone by two pipes 72 and 73. In this case also the cooling of the coke takes place in two stages between which the fractions of recycled gas are divided, as previously indicated.
• These electrodes also have an L-shaped profile, on which a slope accumulates. highly graphitized balls.
• each phase of the current supplies a pair of copper electrodes from a transformer 76.
• the electrodes of the same phase are arranged opposite one another along each of the large faces of the furnace and are separated from the pair of adjacent electrodes by a refractory insulating wall 77.
• the circular oven has an inner enclosure 80 in the form of a warhead made of a refractory material, while the structure of the enclosure 3 of the oven remains identical in all its peripheral parts.
• This enclosure 80 carries a central electrode 81, frustoconical, which ensures the return of the currents crossing the solid mass of hot balls during coking and coming from a circular peripheral electrode 82 of L-shaped section current along the interior perimeter of the tank above the edge 67.
• This provision aims to avoid parasitic currents between the electrodes supplied by different phases, and to ensure the passage of current in the center of the furnace.
• Power is supplied between the peripheral electrode 82 connected as an anode and the central electrode 81 forming the cathode, by a direct current source, for example a rectifier 83, or a single-phase current source for a small capacity oven.
• a direct current source for example a rectifier 83, or a single-phase current source for a small capacity oven.
• the ogival enclosure 80 is mounted on a rod 84 passing through its center a column 85 ensuring the support and the mobility of the annular rotary hearth 86.
• the ogival enclosure 80 can be moved vertically under the action of a jack 87 placed under the rod 84.
• the rod 84 is surmounted by an insulator 88 which prevents the passage of parasitic currents back along the rod 84.
• the central electrode 81 in the form of a truncated cone is made of an abrasion-resistant material such as densified silicon carbide sufficiently electrically conductive to limit localized heating of the walls of the cathode 81.
• the cathode 81 rests on a sleeve 89 made of a refractory insulating material.
• the return currents through the cathode 81 flow to the bottom of the furnace through a cooled, insulated conductor 90 housed in the hollow axis of the rod 84.
• the column 85 is mounted to slide, for example by a system of grooves not shown, in a conical ring gear 91 ensuring the rotational drive of the column thanks to a conical pinion 92 with which it engages, the pinion 92 being mounted at the end of the output shaft of a gearmotor unit 93.
• the vertical sliding of the column is ensured by a jack 94.
• the coke extraction rate, homogeneous over the entire periphery is adjusted by adjusting the rotation speed of the dosing hearth and the height thereof.
• the cathode 81 is cooled by circulation from a pipe 95 of a stream of refrigerated gas which escapes through the annular clearance formed between the ogival enclosure and the column 85 at the place where the enclosure 80 comes to style the latter.
• the electric heating is carried out by induction.
• the heating means arranged at the base of the coking zone 21 comprise an induction coil 100 coaxial with the enclosure 3 and housed in the refractory wall 2 of the furnace.
• Vertically laminated mild steel cores 101 are arranged radially around the coil 100 and channel the field return lines.
• the coil 100 is supplied by a generator 102 at medium frequency, between approximately 50 and 1000 Hertz.
• the electrical conductor which constitutes the coil 100 is a hollow tube, in which circulates a cooling fluid introduced at 103 and withdrawn at 104, which is itself connected by conductors 105 and 106 to the generator 102.
• the laminated cores 101 constitute a magnetic yoke cooled by circulation of cooling fluid introduced by the pipe 107 and withdrawn by the pipe 108.
• this first variant has the disadvantage of unevenly heating the balls passing through the wall and those passing through the center of the oven, which risk being insufficiently heated.
• the ball beds arranged outside will have a temperature and an electrical conductivity significantly higher than the center balls, which will lead to different end-of-coking temperatures and an uneven quality of the coke balls, in the center and at the wall.
• the oven comprises means of electric induction heating which comprise, in addition to an induction coil 110 coaxial with the enclosure 3 and housed in the refractory wall 2 of the oven, an interior enclosure 111 in the form of an ogive made of a refractory material which includes means for strengthening the magnetic field in the vicinity of the furnace axis.
• the refractory material constituting the enclosure 111 may be, for example, made of silicon carbide bonded to silicon nitride, the electrical insulation properties of which are sufficient for the envisaged application and the resistance to abrasion and to thermal shock is excellent. .
• These means can consist of a set of mild steel cores, vertically laminated 112, arranged radially. housed in the warhead enclosure 111.
• an internal induction coil 113 coaxial with the coil 110 supplied in phase with the latter and housed in the warhead enclosure 111.
• the mild steel cores laminated vertically 112 and arranged radially are inserted into the coil 113 coaxially with the latter.
• the induction coil 110 consists of a hollow electrical conductor with helical winding in which circulates a cooling fluid supplied at 114 and withdrawn at 115.
• the internal induction coil 113 is produced in a similar manner and cooled by circulation of a cooling fluid between the points of arrival 116 and of exit 117, this cooling circuit emerging outside the oven by circulation in a column 118, of smaller diameter than the enclosure in the shape of a warhead 111 and supporting the latter.
• Column 118 passes through the rotary hearth of the oven as illustrated in more detail for the first embodiment of the induction heater shown in FIG. 7.
• All of the laminated cores 113 constitute an internal induction cylinder head also cooled by circulation of a cooling fluid supplied by a central pipe 119 arranged along the axis of the column and opening at the top of the cores, the return of the fluid being ensured by a pipe coaxial and external to the pipe 119.
• Cores 120 vertically laminated and arranged radially outside the coil 110 forming an external induction yoke cooled by a circulation of a cooling fluid supplied by a line 121 and withdrawn by a line 122.
• a medium frequency generator 123 supplies the coils 110 and 113 in series via a conductor 124 connected to the input of the coil 110, then a conductor 125 connecting the output of the coil 110 to the input of the coil 113 and a conductor 126 ensuring the return of the output of the coil 113 to the generator 123.
• the coils 110 and 113 placed in the furnace opposite one another make it possible to associate their respective field of induction to simultaneously and homogeneously heat the balls passing along the peripheral walls of the enclosure 3, and of the walls of the inner enclosure 111.
• the induction heating means consist of a set of pairs of induction coils arranged radially in the refractory wall of the furnace, thus defining an external inductor generating a rotating field horizontally passing through the tank.
• FIG. 11 two coils 130. 131 having their axes merged and arranged radially and diametrically opposite are wound on horizontally laminated magnetic steel cores forming inductors 132,133.
• the coils 130 and 131 are supplied on the same phase of a polyphase current marked 1, so that the magnetic field passes radially through the tank, that is to say that the end faces facing the coils 130 and 131 are of opposite polarities.
• each pair of coils 130, 131 which represents a phase is regularly shifted in the inductor so that the resulting field rotates at the frequency of the supply currents and generates eddy currents in the mass of the coked balls.
• the inductors 132, 133 are cooled by circulation of a cooling fluid supplied by a circuit entering through the line 135 and leaving through the line 136.
• a generator 137 three-phase of medium frequency, supplies the coils as shown in FIG. 11 for two coils in an axial cutting plane.
• the horizontal section shows the feeding which takes place as shown in Fig. 13 by considering only the inductors outside the oven enclosure.
• the oven further comprises an internal enclosure 140 in the shape of a warhead, made of a refractory material, in which is housed an internal inductor constituted by a set of radial coils arranged opposite the coils of the external inductor and determining a set of pairs of coupled coils which cooperate to generate a radially rotating field between the external inductor and the internal inductor.
• a coil 130 of the external inductor is associated with a coil 130a supplied in such a way that the opposite end faces of the coils are of opposite polarities.
• the coil 131 is associated with a coil 131a.
• the coils 130a and 131a are wound on a horizontally laminated magnetic steel inductor traversed by a cooling circuit consisting of a central supply tube 141 and peripheral return tubes 142 (Fig.13).
• the electric heating means of the oven comprise, in the coking zone, conduction heating means with L-shaped peripheral electrode 150 and central electrode 151 as described with reference to FIG. 7, supplied from a rectifier 152 and induction heating means comprising an axial coil 153, as described with reference to FIG. 9, supplied from a medium frequency current source 154. and optionally a set of mild steel cores, vertically laminated 156, arranged radially, housed in the support column 157 of the electrode 151, as described with reference in Figure 10.
• the axial coil 153 is then housed in the coping 155 projecting from which the electrode 150 sits and below the latter.
• This mixed assembly combining inductive heating at the periphery of the tank coupled with conductive central heating, is intended for medium and large capacity ovens. It combines: - an inductive heating by a simple coil coaxial with the tank housed in the refractory lining of the furnace.
• This coil identical to the basic solution proposed for the inductive heating of FIG. 9, provides heating for the outer layers.
• This provision relates to the conduction current flows towards the electrode around which the balls are heated because it develops there, by reduction of section, a higher current density and power density.
• This association of an induction coil with heating by conduction between a central electrode and a peripheral electrode also makes it possible to cause the rapid rotation of the conduction currents by the action on these currents of the field lines created by the external coil. .
• Inductive heating uses variable fluxes generated by induction coils totally external to the mass of the balls during coking and makes it possible to overcome, in large part, the problems of variation of the contact resistance between balls and in contact electrodes.
• the electromagnetic induction developed in a ball of balls allows density levels varying within wide limits.
• the developed power can reach 5 to 10 Megawatts per m3 of hot and coked balls, while it is considerably lower by conduction.
• This electrical power greater than the only thermal requirement of electrical coking, developed in the mass of balls, can be used to reduce, by the carbon of the coke and by the volatile matters of the binders, fines of oxidized ores or dusts which can be incorporated into composite balls.
• the present invention finally includes a process for manufacturing molded coke making it possible to add to the mixture of coals to be compacted into balls:
• Iron oxide fines and dust concentrates, steelworks dust and blast furnace gas, dust from dedusting installations, ore agglomerations, etc.
• the invention also relates to a method and a device making it possible to dissipate, in a uniform and homogeneous manner, significant volumetric electrical powers, developed by the Joule effect of induced electric currents, in a medium conductive granule which can thus be brought to high temperature.
• This granulated bed having a high specific surface can be used to heat or superheat gases, liquids, melt solids, and vaporize liquids by superheating the vapors thus produced.
• the conductive granulated bed is made of refractory and sufficiently conductive materials, in calibrated pieces, in grains, in full or hollow and tubular cylindrical elements, in rings, in balls or pellets, briquettes.
• the refractory materials composing the conductive granulated bed can be constituted by calibrated pieces and grains of carbon, graphite, cokes, or by rings, pellets, and cylinders of silicon carbide, molybdenum silicide, diboride of zirconium or by balls, pellets, briquettes of coal paste and of coking mixtures.
• the granulated bed is chosen according to its electrical resistivity, its refractoriness, its specific surface and its permeability, and finally its resistance to oxidation and corrosion for the use which is made of it.
• Examples of use include: a) - gas heating. - heating and superheating of reducing gases on a bed of calibrated pieces of coke; regeneration and generation of reducing gases by conversion to H 2 and CO of the H 2 O and CO 2 contained in the gas, on a coke bed at 800-1000oC; - cracking and oxidation of the heavy hydrocarbons contained in the raw and wet coke oven gas on a coke bed at 900-1100oC, to carry out in one step the "purification" thermal of the raw and hot coke oven gas, and eliminating all condensable products; - overheating at 1200oC of reducing gases, intended for the “direct” reduction of iron oxides, on a bed of coke; overheating at high temperature of 1200-1350oC of preheated air, possibly under pressure and superoxygenated like the wind from a blast furnace on a bed of tubular conductive elements in silicon carbide or molybdenum silicide in the form of rings.
• an oven comprising heating means as shown in FIGS. 7 to 14.
• the conductive granulated bed is compacted in the tubular enclosure of the oven whose walls are lined with insulating refractories. This granulated bed rests on a refractory grid through which the gas to be overheated is blown. It can also be placed between two layers of non-conductive material such as sand, so as to center the lines of flight.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Coke Industry (AREA)
• Furnace Details (AREA)
• Vertical, Hearth, Or Arc Furnaces (AREA)

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• 1985
  • 1985-09-26 FR FR8514291A patent/FR2587713B1/fr not_active Expired
• 1986
  • 1986-09-23 IN IN747/MAS/86A patent/IN167885B/en unknown
  • 1986-09-25 ZA ZA867313A patent/ZA867313B/xx unknown
  • 1986-09-25 CA CA000519078A patent/CA1297445C/en not_active Expired - Lifetime
  • 1986-09-25 CN CN86106940A patent/CN1014152B/zh not_active Expired
  • 1986-09-26 ES ES8602483A patent/ES2001712A6/es not_active Expired
  • 1986-09-26 JP JP61505201A patent/JPS63501019A/ja active Pending
  • 1986-09-26 DE DE8686905848T patent/DE3667297D1/de not_active Expired - Lifetime
  • 1986-09-26 EP EP86905848A patent/EP0240527B1/de not_active Expired
  • 1986-09-26 WO PCT/FR1986/000332 patent/WO1987002049A1/fr active IP Right Grant
  • 1986-09-26 BR BR8606892A patent/BR8606892A/pt not_active Application Discontinuation
  • 1986-09-26 AU AU64050/86A patent/AU590013B2/en not_active Ceased
  • 1986-09-26 US US07/059,872 patent/US4867848A/en not_active Expired - Fee Related
• 1987
  • 1987-05-25 KR KR870700443A patent/KR880700048A/ko not_active Application Discontinuation
  • 1987-05-25 SU SU874202768A patent/SU1825369A3/ru active

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