EP0036609B1 - Procédé et dispositif pour allumer un mélange à fritter - Google Patents

Procédé et dispositif pour allumer un mélange à fritter Download PDF

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Publication number
EP0036609B1
EP0036609B1 EP81101962A EP81101962A EP0036609B1 EP 0036609 B1 EP0036609 B1 EP 0036609B1 EP 81101962 A EP81101962 A EP 81101962A EP 81101962 A EP81101962 A EP 81101962A EP 0036609 B1 EP0036609 B1 EP 0036609B1
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EP
European Patent Office
Prior art keywords
igniting
kiln
burners
cover
gases
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP81101962A
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German (de)
English (en)
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EP0036609A1 (fr
Inventor
Horst Dr.-Ing. Bonnekamp
Baldur Sauer
Heinrich Wolkewitz
Günter Hepp
Walter Kraemer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EOn Ruhrgas AG
Original Assignee
Ruhrgas AG
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Publication date
Priority claimed from DE3010844A external-priority patent/DE3010844C2/de
Priority claimed from DE19803010845 external-priority patent/DE3010845C2/de
Application filed by Ruhrgas AG filed Critical Ruhrgas AG
Priority to AT81101962T priority Critical patent/ATE4916T1/de
Publication of EP0036609A1 publication Critical patent/EP0036609A1/fr
Application granted granted Critical
Publication of EP0036609B1 publication Critical patent/EP0036609B1/fr
Expired legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B21/00—Open or uncovered sintering apparatus; Other heat-treatment apparatus of like construction
    • F27B21/06—Endless-strand sintering machines
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/16—Sintering; Agglomerating
    • C22B1/20—Sintering; Agglomerating in sintering machines with movable grates

Definitions

  • the present invention relates to a method for igniting a sintering mixture consisting of a solid fuel and a sintering material, in particular a sintering oil mixture, on a sintering machine, in which the sintering mixture is passed under an ignition furnace which is largely closed off by end and side walls and a ceiling .
  • a sintering mixture consisting of a solid fuel and a sintering material, in particular a sintering oil mixture
  • an ignition furnace which is largely closed off by end and side walls and a ceiling .
  • the invention further relates to a device for carrying out such a method with an ignition furnace which is open at the bottom and has two end walls, two side walls and a ceiling and with a sinter belt which can be moved beneath it essentially horizontally in the direction of the connecting line between the end walls, for receiving a sinter mixture, the end walls and the side walls are pulled down to close to the sintered mixture, so that a hood-like ignition furnace space is formed which is largely sealed off from the outside atmosphere.
  • Ignition furnaces for igniting sintered mixtures are often designed as hoods that are closed at the top and sides, and are open at the bottom. Under these ignition furnaces, the sintered mixture is transported through in a layer thickness of approx. 40 cm on a so-called sintering belt, which usually consists of an infinite series of grate wagons directly adjoining one another.
  • the sinter mixture essentially consists of iron ore as sintered material and coke as a solid fuel, as well as some additives depending on the steel production process.
  • the latter In order to ignite the sintered mixture as it passes under the ignition furnace, the latter is equipped with burners which generate the temperatures necessary for the ignition. There are intake ducts under the sintering belt, with the aid of which the combustion gases are sucked out of the ignition furnace through the sintering mixture.
  • Ignition furnaces of the type described in the introduction have already become known in various embodiments.
  • ignition furnaces in which the burners are arranged obliquely downwards in the ceiling or in the end walls, the burner jets of the individual burners being directed onto the surface of the sintered material.
  • This method leads to a strong heating of the sintered material surface, but to an uneven ignition, because the points of the sintered material surface that lie in the center of the respective burner jet are heated more intensely than the areas that lie between the burner jets.
  • a modification of this type is that the burners are arranged in the end walls of the ignition furnace against each other and directed obliquely downwards. In the middle of the ignition furnace, where the flue gases from the burners collide, a flow is directed towards the ceiling, through which hot pieces of sintered goods are carried upwards, which then lead to ever increasing caking on the roof of the furnace.
  • the burner jets collide after 1 to 2.5 m with the narrow width of the sintering furnace of about 2 to 5 meters, which creates the risk of incomplete combustion and of the sintering bed being stirred up in the middle of the furnace.
  • the highest possible temperature for a certain fuel input is achieved in the inlet-side section due to the stoichiometric mode of operation of the burners.
  • the oxygen necessary for the combustion is only supplied in the heat treatment part in that the burners are operated there with a larger excess of air.
  • the heat generated by the inlet-side burners is only partially used, so that an unnecessarily high energy consumption results.
  • the present invention is therefore based on the object of providing a method and a device for igniting a sintered mixture of solid fuel and sintered material, which enable the sintered mixture to be ignited quickly and uniformly with the lowest possible investment and operating costs (energy consumption).
  • This object is achieved according to the invention in a method of the type specified in the introduction in that the flue gases are fed from the one or more approximately stoichiometrically operated burners into the upper region of the ignition furnace and that the gases with an increased oxygen content are fed into the lower region of the ignition furnace , in such a way that a furnace atmosphere results which is hotter and less oxygen-rich in the upper region of the ignition furnace, and cooler and oxygen-rich in the lower region.
  • the invention is based on the knowledge that the ignition process is significantly improved if the sintered mixture is simultaneously exposed to the high temperature of an approximately stoichiometric combustion and an adequate supply of oxygen. According to the invention, this can be achieved by the measures described above.
  • a stoichiometrically operated burner is known to be supplied with fuel gases and oxygen (the latter usually as a constituent of atmospheric air) in such a ratio that the oxygen content corresponds to a good approximation to the amounts necessary for the complete combustion of the fuel.
  • the flue gases resulting from such a combustion contain only very small amounts of free oxygen, since this was practically completely used up for combustion.
  • With stoichiometric combustion the highest possible temperature is reached for a given fuel input and other boundary conditions. Because these flue gases are fed into the upper region of the furnace in the present invention, this upper region and in particular the furnace roof are thus heated to a very high temperature with the least possible use of fuel.
  • a gas with an increased oxygen content is fed into the lower region.
  • This gas can be any gas mixture in which it is only essential that it contains an increased proportion of free oxygen, which is suitable for accelerating the ignition process on the surface of the sintered material.
  • This gas mixture preferably contains at least 5%, particularly preferably at least 10%, of free oxygen.
  • the gases with increased oxygen content fed into the lower region of the ignition furnace can, for example, be a preferably hot gas mixture from another process of the same company. Heated air or pure oxygen can also advantageously be fed into the lower region of the ignition furnace. It is only essential that there is a furnace atmosphere in the lower region of the furnace with an increased proportion of free oxygen compared to the upper region. These oxygen-rich gases are generally considerably cooler than the flue gases from stoichiometric combustion in the upper part of the furnace. Surprisingly, however, it has been found that the ignition process, in particular with regard to the surface of the sintered mixture, is nevertheless significantly improved if the process according to the invention is used.
  • upper region and“ lower region ”of the ignition furnace are not to be understood as limiting the fact that the gases supplied to the furnace must adhere to certain limits within the furnace volume. It is only essential for the invention that the flue gases fed into the upper region of the furnace heat in particular the furnace roof and the gas layers underneath to very high temperatures and that an atmosphere with an increased oxygen content is maintained above the sintered mixture. The transition between the two areas is necessarily fluid and depends on the details of the respective furnace design.
  • the present invention also differs decisively from the device described in US Pat. No. 3,318,590.
  • This is used for pelleting, which is used in particular for fine ores that are not suitable for sintering.
  • the good to be pelletized is thereby moistened to form balls on a turntable or in a drum.
  • These are first pre-dried in a device described in this prepublished US patent, for example, and then baked together under the action of high heat.
  • the gases with increased oxygen content which are fed to the lower region of the ignition furnace, consist at least partly of flue gases from a combustion with an air ratio ⁇ equal to 2 to equal to 5.
  • the air ratio ⁇ gives the relation between that of the burner actually supplied amount of free oxygen and the amount of free oxygen necessary for stoichiometric combustion.
  • A 1 therefore corresponds to stoichiometric combustion, while a larger X leads to a flue gas with a corresponding residue of free oxygen.
  • This flue gas then has an increased oxygen content in the desired manner and, as practical tests have shown, when using the limits according to the invention between X equal to 2 and ⁇ equal to 5 at the same time is such a high temperature that uniform and rapid ignition of the sintered mixture is ensured .
  • more flue gases from the approximately stoichiometrically operated burners can be supplied in the entrance area of the ignition furnace, and more of the gases with increased oxygen content in the exit area.
  • This measure is based on the knowledge that particularly high temperatures and relatively little oxygen are required to ignite the top layer in the entrance area of the furnace, while as the ignition process progresses, the burning layer gradually propagates deeper into the sintered bed, thereby preheating the material considerably deeper layers of the sintered mixture is reached. That is why less heat is useful in the rear area of the ignition furnace, but a slightly higher proportion of oxygen makes sense.
  • the essential difference from the known method in this embodiment is that in the entire area of the ignition furnace there is a layer of gases with an increased proportion of free oxygen, preferably at least about 5%, above the sintered mixture.
  • the gases in the method according to the invention can be supplied to the different furnace areas in different ways.
  • the stoichiometrically operated burners can be installed in the upper region of the furnace, for example on the side and end walls, and can be operated at a relatively low outflow speed in order to generate the desired hot and low-oxygen atmosphere in the upper region of the furnace.
  • nozzles or burners operated with an over-stoichiometric gas mixture can be provided in the side walls or in the end walls of the ignition furnace and serve to supply the gases with an increased oxygen content.
  • the burners or nozzles themselves can also be arranged elsewhere and only the gases emerging from them can be directed in such a way that the desired furnace atmosphere is achieved.
  • Burners which are arranged in the side wall of the furnace, which are operated approximately stoichiometrically at least in the entrance area of the ignition furnace and whose flue gases are guided approximately horizontally in parallel flow to the center of the furnace, are preferably proposed that the gases with increased oxygen content emerge from nozzles which are arranged below the approximately stoichiometrically operated burner and in the longitudinal direction between them in the side wall of the furnace and from which the gases with increased oxygen content are fed horizontally or inclined to the sintered mixture.
  • Such a measure allows the advantages of the method according to the invention to be used with relatively little investment, even in existing systems with side burners.
  • a particularly simple construction of the ignition furnace and a particularly good uniformity of the ignition process are achieved according to a particularly preferred method proposal if the flue gases from the approximately stoichiometrically operated burners and the gases with increased oxygen content from opposite side walls or, which is particularly advantageous in the case of stoves which are not too long, emerge from the opposite end walls of the furnace.
  • the flue gases from the approximately stoichiometrically operated burners should preferably be directed towards the ceiling of the ignition furnace, specifically at an angle of up to 30 °, angles of 5 to 10 ° having proven particularly advantageous.
  • the gases with an increased oxygen content should be directed downward at a maximum angle of 50 °, preferably 20 to 35 °, relative to the horizontal towards the sintered mixture.
  • this circulating flow is also achieved if the two gas flows are each guided horizontally, but the flue gas flow from approximately stoichiometric combustion in the upper region of the furnace, in particular near the furnace ceiling, and the gas flow with an increased oxygen content in the lower furnace area, especially in the vicinity of the sinter mixture.
  • This embodiment also results in a circulating gas flow.
  • An embodiment in which the angle with respect to the horizontal is 0 ° for one or both gas flows is therefore expressly included in the embodiment described above.
  • the flue gases from approximately stoichiometric combustion and possibly also the gases with an increased oxygen content are each supplied from the top of the furnace in such a way that the distribution of the furnace atmosphere according to the invention is achieved.
  • the supply from the ceiling is particularly advantageous if a particularly long ignition furnace is used.
  • the bars of an ignition furnace that is to say the throughput of sinter mixture per unit of time, are directly dependent on the speed at which the sintering belt is operated.
  • the ignition process i.e. the penetration of the burning layer of solid fuel, takes a certain time through the entire layer thickness of the sintered mixture, it is necessary that correspondingly long ignition ovens are used at high powers.
  • the sintered mixture be transported immediately after the ignition process taking place under the ignition furnace through a zone in which it is essentially shielded from the flue gases of the ignition furnace and through which an oxygen-containing gas, in particular air, flows. whereby it is largely insulated against heat radiation.
  • the entire sintering process takes place, for example, on a sintering belt that is more than 100 m long, with a typically about 10 to 15 m long ignition furnace only over the first part. This distance is sufficient to ignite the top layer of the sinter mixture under the ignition furnace. The length of the sintered strip and the speed of its movement are then such that at the end of the sintered strip the burning layer has migrated from top to bottom through the entire thickness of the sintered mixture.
  • a corresponding device is characterized in that a thermal insulation hood directly adjoining the ignition furnace with thermally insulating walls, which is open at the bottom towards the sintering machine, the side and end walls of which extend up to the sintering mixture and the ceiling has openings for sucking in combustion air has, is provided.
  • the combustion air is sucked in, as usual in the known devices, through suction shafts under the grate carriage of the sintering belt and thus flows through the entire sintering mixture.
  • the combustion air can advantageously already be preheated in the process, that is to say in the course of any heat-releasing process steps of the same system.
  • the cooling bed of the sintering machine for example, is suitable for this.
  • the finished sinter falls at the end of the sintering belt onto a sinter cooler through which air is sucked.
  • This air is still heated up considerably, but in contrast to the air that has flowed through the sintering belt, contains very little flue gas, since there is no longer any combustion on the cooling bed.
  • This preheated air is particularly suitable for use in the rest of the process. In particular, it can also be used advantageously as preheated combustion air for the burners in the ignition furnace.
  • the advantageous effect of using a thermal insulation hood is based essentially on the fact that the heat radiation from the surface of the sintered material to the environment in the area of the thermal insulation hood is largely prevented and is used in the heat exchange with the intake combustion air.
  • the surface temperature of the sintered material is still many 100 ° C. after leaving the ignition furnace.
  • heat is lost to a considerable extent through radiation, with the known harmful consequence that the upper part of the sintered bed is poorly lowered.
  • there is only air in the thermal insulation hood according to the invention which is not heavily contaminated by exhaust gases. This is advantageous for the propagation of the combustion in the areas below the surface.
  • the openings in the ceiling of the thermal insulation hood are designed so that they consist of fixed parts and on up and down movable parts arranged above.
  • the latter parts are made wider than the gaps between the fixed parts so that they overlap these gaps.
  • the direct radiation of the heat from the surface of the sintered material to the environment is also prevented at the openings for the intake of the combustion air. This further reduces the heat loss of the surface of the sintered bed in the desired manner.
  • the pressure in the thermal insulation hood can be adjusted so that on the one hand the combustion air is sucked in essentially through the openings in the ceiling and thus a uniform flow distribution in the thermal insulation hood is produced, with only a small part of the air due to the inevitable leaks between sintered grate cars and thermal insulation hood and between the sintered bed and the outlet end wall of the thermal insulation hood.
  • the opening is only set as large as required.
  • the sintering mixture is located in a known manner on a sintering belt formed from grate wagons and has a thickness of usually about 40 cm. For the sake of clarity, these known details are not shown in the drawing.
  • the ignition furnace consists of a ceiling 9, an end wall 4 on the inlet side and an end wall 5 on the outlet side.
  • the side walls in FIG. 1 run parallel to the plane of the paper and essentially perpendicular to the sintering belt along its edges. Overall, the ignition furnace 3 thus forms a hood-like closed space.
  • the end walls 4 and 5, like the side walls not shown in the figure, are pulled down in a known manner to just above the surface of the sintering mixture 1.
  • the ceiling 9 of the ignition furnace and also its walls are thermally insulated in a known manner.
  • a number of burners are arranged in the end walls 4 and 5, the burner axes of which are provided in the figure with the reference numerals 6 for the inlet-side burners and 7 for the outlet-side burners.
  • the number of burners arranged on the respective side is determined by their performance, the width of the sintering belt and other factors and is not the subject of the invention. In any case, in the preferred embodiment shown, all the burners on the inlet side and all burners on the outlet side are aligned parallel in their axial direction and evenly distributed over the width of the respective end wall.
  • the inlet-side burners are directed at an angle of 5 ° with respect to the horizontal against the ceiling of the ignition furnace 3.
  • the burners on the outlet side are oriented downwards against the surface of the sintered mixture at an angle of 30 ° with respect to the horizontal. This orientation of the respective burner rows on the inlet and outlet sides results in a circulation flow which is shown schematically in the drawing with the reference number 8.
  • the inlet-side burners are operated with an approximately stoichiometric ratio of fuel and oxygen, while in the outlet-side burners the ratio of fuel and air is set such that an air ratio ⁇ greater than 1.3 is maintained.
  • the formation of the flue gas roller in the ignition furnace is additionally improved in that, according to a preferred embodiment, the inlet-side burners are designed in a manner known per se in a short-flame design, while the outlet-side burners are designed in a long-flame design.
  • the outlet-side end wall 5 is oriented perpendicular to the associated burner axis 7. This is particularly advantageous for larger inclinations of the burner axis, in order to enable the burner to be easily fixed in the respective wall and to guide the flue gases cleanly.
  • This preferred design offers the following advantages: It is avoided that the flue gas flow caused by the burner jets forms a jam in the middle of the furnace 3 and, as a result, heated particles of the sintered bed 1 are whirled up and thus annoying caking occurs. Rather, both the inlet-side and the outlet-side burners act in such a way that a rotating flue gas roller 8 is formed in the ignition furnace 3, the direction of rotation of which is maintained in the same direction by both rows of burners.
  • This roller 8 causes the hot flue gases generated by stoichiometric combustion of the inlet-side burners to flow along the ceiling 9 of the ignition furnace 3 from the inlet side to the outlet side, and their heat at the prevailing temperatures predominantly by direct radiation to the sintering mixture 1 and by indirect radiation also delivered to the sintered mixture 1 via the radiant heating of the ceiling 9. It is thus avoided that the individual burner jets are directed onto the sintered bed 1, which causes the described unevenness in the heating. Rather, the heat transfer takes place in the manner described essentially by the heat radiation of the entire gases and the furnace roof 9 in the upper part of the ignition furnace 3, whereby the uniformity of the heating is ensured.
  • any irregularities in the heating that occur in the transverse direction to the transport direction of the sintering machine can be compensated for by differently acting on the burners arranged side by side in the end wall. If it is shown, for example, that the two outer edges of the strip are heated too little, the two outer burners in the end wall can accordingly be subjected to greater pressure.
  • the solution according to the invention thus combines the advantage of uniform heating by radiant heat transfer from the upper furnace area with the possibility of influencing the heat applied to the parts lying next to one another in the direction of transport. This is important because it is not only necessary to produce a uniform sintered good that the entire sintered bed 1 is heated uniformly, but because it is additionally necessary to adapt the heating to the possible differences in the heat requirements of the different parts of the sintered bed lying next to one another in the transport direction . In the burners on the outlet side, which are inclined downwards in a manner known per se and with excess air there is no risk of uneven heating.
  • the lower flow of less hot but oxygen-rich gases emanating from the outlet-side burners serves to provide the oxygen required for the reaction of the solid fuel.
  • the heat radiation from the upper flue gas layer onto the sintered bed is absorbed only relatively little by the lower flue gas layer, since the latter in particular has only relatively little heat radiation absorbing flue gas components because of its high excess of ventilation.
  • the particular advantage of this preferred type of construction is therefore that a high and uniform heat flow density is provided for the ignition and at the same time the oxygen required for the combustion of the solid fuel is supplied at a temperature. A quick and even ignition is thus brought about by making appropriately heated combustion air available. After the first ignition process of the surface, the temperature and thus the sintering of the top layer of the sintered bed is further improved. This avoids the disadvantageous effect in the known types that the sintering of the top layer remains imperfect. Since the top layer can also be used as a finished sinter, the throughput of the system and the specific heat consumption per ton of finished sinter are reduced.
  • FIGS. 2 and 3 Another such preferred embodiment is shown in FIGS. 2 and 3. Those components which correspond to the previously described embodiment are identified by the same reference numerals, provided with an additional line.
  • the essential peculiarity of the device shown in FIGS. 2 and 3 is that both the burners for supplying the flue gases from approximately stoichiometric combustion, and the nozzles for supplying the gases with increased oxygen content are passed through the roof of the furnace. You can see ceiling burners 10, ceiling nozzles of long type 11 and ceiling nozzles of short type 12.
  • the ceiling burners 10 are preferably designed as so-called ceiling radiation burners. This type of burner known per se is distinguished by the fact that the media (fuel and air) leave the burner with a certain swirl due to the shape of the burner nozzles.
  • the streamlines of the media spiral outwards and outwards after leaving the burner. This creates a short flame on the one hand and a suction in the center of the burner, on the other, through which the media or flue gases are drawn upwards in the center of the spiral.
  • the basic shape of the streamlines is shown in FIG. 2 insofar as it can be seen in the cross section.
  • nozzles 11 and 12 which are preferably designed as parallel flow nozzles, serve to supply the gases with an increased oxygen content.
  • these consist of a tube for air or another oxygen-containing gas mixture or of concentric tubes for fuel and air. They have a smooth surface and overall are designed in such a way that the media emerge at the end of the nozzles relatively slowly and in a laminar flow, so that an elongated flow path is reached towards the surface of the sintered mixture.
  • the nozzles are preferably designed as longer tubes 11 or shorter tubes 12, the longer tubes being more suitable for guiding the gases with increased oxygen content without great mixing with the flue gases from the ceiling burners in the vicinity of the sintering mixture.
  • Fig. 3 clearly shows that the ceiling radiation burner 10 and the ceiling nozzles 11 and 12 are arranged in a checkerboard manner and offset from one another in such a way that the ceiling nozzles 11, 12 are each centered in the fields which are formed by the ceiling radiation burners as end points.
  • Such a uniformly alternating distribution of the ceiling nozzles and ceiling radiation burners results in a particularly uniform ignition of the surface of the sintering mixture.
  • the individual rows of burners arranged one behind the other in the direction of movement of the sintering belt can also be acted upon with different amounts of fuel and air, for example in such a way that the flow rates that are passed decrease towards the outlet side.
  • the distance between the rows of burners can of course also be varied accordingly.
  • an embodiment with flue gases or gases with an increased oxygen content that are supplied through the roof of the furnace is particularly advantageous for long ignition furnaces, where such an embodiment also enables a particularly precise adjustment of the temperature distribution both over the width of the sintering belt and in particular over the length of the igniter allowed.
  • a preferred variant of the device according to the invention is characterized in that there are tubes for supplying the gases with an increased oxygen content, which extend between the side walls of the ignition furnace. These tubes have nozzles, from which the gases exit essentially downwards, be it obliquely or directly vertically. In special applications, horizontal gas routing from the pipes can also be useful. It also makes sense under certain application conditions not to run the pipes continuously from one side wall to another, but only to let a certain part protrude into the furnace chamber from one side or end wall.
  • thermal insulation hood to be used preferably, which is provided with the reference number 20 in its entirety.
  • the sintering belt moves under the thermal insulation hood in the direction of arrow 21.
  • the essential parts of the sintering belt are shown in dashed lines. These are the grate wagons 22 that roll on the rails 26 with wheels 24. Also shown in dashed lines is the outlet end 28 of an ignition furnace.
  • the thermal insulation hood 20 has two end walls 30 and 32, one composed of a plurality of side wall elements 34.
  • the ceiling 38 consists of fixed parts 40 and up and down movable parts 42. As can be seen from FIG. 4, the up and down movable parts 42 are larger in their horizontal extent than the gaps between the fixed parts 40. The movable parts 42 thus overlap the fixed parts 40. All walls 30, 32, 36 and 38 of the thermal insulation hood 20 are thermally insulated in a known manner. The overlapping construction of the ceiling elements 40 and 42 ensures that the heat losses under the thermal insulation hood, insofar as they arise from radiation, are largely prevented even when the openings 44 in the ceiling 38 are open.
  • the thermal insulation hood thus provides good thermal insulation above the sintering mixture located in the grate carriage 22.
  • Under the grate car are the intake ducts, not shown in the drawing, so that oxygen-containing gases, in particular air, are drawn in through the sintered mixture.
  • This air can penetrate through the bridge 44 into the thermal insulation hood 20.
  • this air can already be preheated in the process.
  • the thermal insulation hood allows the creation of a controlled and thermally insulated atmosphere in the area of a sintering machine immediately adjacent to the ignition furnace. It has been found that the ignition of the surface of the sintering mixture can be decisively improved by this measure or the fuel expenditure required for this can be considerably reduced.
  • FIGS. 4 and 5 The construction used to adjust the thermal insulation hood according to the invention is shown only schematically in FIGS. 4 and 5. It consists essentially of a frame 46, from which a common support beam 50 for the various movable ceiling elements 42 is suspended via cables 48. The cable 48 is guided by support rollers 52 and deflection rollers 54, which are attached to the frame 46. A winch 56, shown schematically, is provided for driving the cable 48. This winch 56 can be controlled so that the movable elements 42 can be brought into any distance from the fixed elements 40 of the ceiling 38 and locked there.
  • the fixed elements 40 of the ceiling 38 as well as the end walls 30 and 32 and the elements 34 of the side walls 36 are fastened in a stationary manner above the sintering belt by a construction familiar to the person skilled in the art and not shown in detail in the figures. It is important that the side and end walls extend close to the sintered mixture so that the space below the thermal insulation hood 20 is largely closed.

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Claims (19)

1. Procédé pour l'inflammation d'un mélange de frittage formé d'un combustible solide et d'une matière à fritter, en particulier d'un mélange de lit de fusion à fritter, sur une machine à fritter, dans lequel on fait passer le mélange de frittage sous un four d'allumage qui forme une cavité isolé dans une large mesure par des parois frontales et latérales et un toit, des gaz de combustion provenant d'un ou plusieurs brûleurs à fonctionnement approximativement stcechiométrique étant introduits dans le four d'allumage, où ils chauffent et enflamment par rayonnement et convection la surface de la matière à fritter, tandis que des gaz à teneur augmentée en oxygène sont en outre également introduits dans ledit four, lequel procédé est caractérisé en ce que les gaz de combustion provenant du ou des brûleurs à fonctionnement approximativement stcechiométrique sont introduits dans la zone supérieure du four d'allumage et en ce que les gaz à teneur élevée en oxygène sont introduits dans la zone inférieure du four d'allumage, plus précisément de telle sorte que l'on obtient une atmosphère de four qui est plus chaude et plus pauvre en oxygène dans la zone supérieure du four d'allumage, plus froide et plus riche en oxygène dans la zone inférieure de celui-ci ;
2. Procédé selon la revendication 1, caractérisé en ce que les gaz introduits dans la zone inférieure du four d'allumage contiennent plus de 5 % d'oxygène libre.
3. Procédé selon la revendication 2, caractérisé en ce que les gaz introduits dans la zone inférieure du four d'allumage comprennent des gaz de combustion provenant d'une combustion avec un rapport d'air λ compris entre 2 et 5.
4. Procédé selon l'une des revendications précédentes, caractérisé en ce qu'on introduit dans la zone d'entrée du four d'allumage davantage de gaz de combustion provenant de brûleurs à fonctionnement approximativement stœchiométrique et dans la zone de sortie dudit four, davantage de gaz à teneur élevée en oxygène.
5. Procédé selon l'une des revendications précédentes, dans lequel les gaz de combustion produits par des brûleurs à fonctionnement approximativement stcechiométrique sont amenés depuis les parois latérales du four d'allumage, approximativement horizontalement en courant parallèle, caractérisé en ce que les gaz à teneur élevée en oxygène provenant de buses disposées au-dessous des brûleurs à fonctionnement approximativement stœchiométrique et en particulier entre ceux-ci, sont introduits horizontalement ou en direction inclinée par rapport au mélange de frittage.
6. Procédé selon l'une des revendications 1 à 4, caractérisé en ce que les gaz de combustion provenant des brûleurs à fonctionnement approximativement stoechiométrique sont dirigés d'une paroi latérale ou frontale vers le toit du four d'allumage, sous un angle de 30° au maximum, de préférence de 5 à 10°, par rapport à l'horizontale, de sorte qu'ils balaient le toit du four d'allumage, et en ce que les gaz à teneur élevée en oxygène sont dirigés de la paroi latérale ou frontale opposée vers le bas, sur le mélange de frittage, sous un angle de 50° au maximum, de préférence de 20 à 35°, par rapport à l'horizontale, de sorte qu'ils balaient le mélange de frittage et que l'on obtient dans l'ensemble, dans le four d'allumage, un courant de gaz circulant.
7. Procédé selon l'une des revendications 1 à 4, caractérisé en ce que les gaz de combustion introduits dans la zone supérieure du four provenant des brûleurs à fonctionnement approximativement stœchiométrique, sont introduits à partir du toit du four d'allumage, de telle sorte qu'ils ne se propagent pratiquement que dans la partie supérieure du four d'allumage et en ce que les gaz à teneur élevée en oxygène introduits dans la partie inférieure du four d'allumage sont introduits à partir du toit du four d'allumage, de telle manière qu'ils se propagent essentiellement dans la zone inférieure du four d'allumage et au-dessus du mélange de frittage.
8. Procédé selon la revendication 7, caractérisé en ce que les gaz de combustion introduits à partir du toit du four d'allumage en provenance de brûleurs à fonctionnement approximativement stœchiométrique sont introduits par I'intermédiaire de brûleurs à rayonnement en voûte disposés de manière connue en elle-même dans le toit du four d'allumage, suivant un axe vertical, grâce à une rotation appropriée des fluides dans le brûleur, de telle sorte que les fluides (combustible et air) s'éloignent tout d'abord du brûleur vers le bas en un mouvement hélicoïdal à coeur creux, puis refluent pour une part notable vers le haut et vers le brûleur, au centre, le long de l'axe du brûleur et sont ainsi recyclés, les vitesses tangentielle et axiale des fluides dans le brûleur étant, de manière connue en elle-même, si grandes que les courants de circulation qui en résultent ne remplissent pratiquement que les deux tiers supérieurs de la hauteur libre entre le lit de frittage et le toit du fourd'allumage, et en ce que les gaz à teneur élevée en oxygène sont injectés vers le bas, de manière connue en elle-même, depuis des buses passant à travers le toit, sous forme de courants parallèles à direction d'écoulement sensiblement verticale, à une vitesse d'environ 5 à 30 m/s, de sorte que ceux-ci se propagent dans la partie inférieure du four d'allumage et que l'aspiration de gaz de combustion provenant de la combustion approximativement stcechiométrique est évitée dans une large mesure, sur le parcours allant du toit à la partie inférieure du four d'allumage.
9. Procédé selon l'une des revendications 1 à 8, caractérisé en ce que le mélange de frittage est transporté, immédiatement à la suite du processus d'allumage qui a lieu sous le four d'allumage, à travers une zone dans laquelle il est pratiquement protégé contre les gaz de combustion du four d'allumage et est traversé par un gaz oxygéné, en particulier de l'air, tout en étant isolé dans une large mesure en direction du haut du rayonnement thermique.
10. Dispositif pour la mise en oeuvre du procédé selon la revendication 1, comportant un four d'allumage (3) ouvert à sa partie inférieure, comportant deux parois frontales (4, 5), deux parois latérales et un toit (9), et une bande de frittage destinée à recevoir un mélange de frittage (1) pouvant se déplacer au-dessous dudit four, pratiquement horizontalement, en direction de la ligne de jonction entre les parois frontales, les parois frontales (4, 5) et les parois latérales étant prolongées vers le bas jusque tout près du mélange de frittage, pour former une cavité de four d'allumage en forme de dôme, isolée dans une large mesure de l'atmosphère extérieure, lequel dispositif est caractérisé en ce que des brûleurs (6) sont disposés sur la paroi frontale (4) située du côté de l'entrée horizontalement ou suivant une inclinaison, en direction du toit du four d'allumage allant jusqu'à 30° par rapport à l'horizontale, et en ce que des brûleurs (7) sont disposés sur la paroi frontale (5) située du côté de la sortie, suivant une inclinaison en direction de la surface du mélange, allant jusqu'à 50° par rapport à l'horizontale, les brûleurs du côté de l'entrée pouvant fonctionner à peu près stcechiométrique- ment tandis que les brûleurs du côté de la sortie peuvent fonctionner avec un rapport d'air X supérieur à 1,3.
11. Dispositif selon la revendication 10, caractérisé en ce que les parois frontales (4, 5) sont dirigées chacune approximativement perpendiculairement à l'axe des brûleurs (6, 7) qui y sont disposés.
12. Dispositif selon l'une des revendications 10 ou 11, caractérisé en ce que les brûleurs (6) du côté de l'entrée sont réalisés suivant un type à flamme courte connu en lui-même et en ce que les brûleurs (7) du côté de la sortie sont réalisés suivant un type à flamme longue connu en lui-même.
13. Dispositif pour la mise en oeuvre du procédé selon la revendication 1, comportant un four d'allumage ouvert à sa partie inférieure et comportant deux parois frontales (5', 6'), deux parois latérales et un toit (9') et une bande de frittage destinée à recevoir un mélange de frittage (1') pouvant se déplacer au-dessous du four, pratiquement horizontalement, dans la direction de la ligne de jonction entre les parois frontales, les parois frontales et les parois latérales étant prolongées vers le bas jusqu'à arriver juste au-dessus du mélange de frittage, pour former une cavité de four d'allumage en forme de dôme, isolée dans une large mesure de l'atmosphère extérieure, lequel dispositif étant caractérisé en ce que dans le toit (9') du four d'allumage sont disposés des brûleurs en voûte (10) en eux-mêmes connus dont les tuyaux d'amenée de combustible et d'air présentent des organes de réglage permettant d'établir ou de régler un rapport d'air X à peu près égal à 1, sont montés dans le toit (9') du four d'allumage, en ce que les brûleurs en voûte (10) sont disposés uniformément, en échiquier et décalés entre eux dans la direction longitudinale du dôme d'allumage, en ce que dans le toit sont disposées, pour l'amenée des gaz à proportion accrue d'oxygène, des buses (11, 12) à axe vertical qui sont montées dans le toit pour l'amenée de gaz à teneur en oxygène élevée, lesquelles buses sont des buses à courants parallèles, formées d'un tube pour l'air ou de tubes concentriques pour le combustible et l'air, et en ce que les buses (11, 12) sont situées chacune au milieu des zones qui sont formées par les brûleurs en voûte à rayonnement (10) constituant les points angulaires.
14. Dispositif selon la revendication 13, caractérisé en ce que les buses (11, 12) d'introduction du gaz à teneur élevée en oxygène sont réalisées sous forme de tubes qui pénètrent suivant un axe vertical dans la cavité du four d'allumage à travers le toit (9').
15. Dispositif pour la mise en œuvre du procédé selon la revendication 1, comportant un four d'allumage (3) ouvert à sa partie inférieure et comportant deux parois frontales (4, 5), deux parois latérales et un toit (9), et une bande de frittage destinée à recevoir un mélange de frittage (1) pouvant se déplacer au-dessous du four, pratiquement horizontalement, dans la direction de la ligne de jonction entre les parois frontales, les parois frontales (4, 5) et les parois latérales étant prolongées vers le bas jusque tout près du mélange de frittage, pour former une cavité de four d'allumage en forme de dôme isolée dans une large mesure de l'atmosphère extérieure, lequel dispositif est caractérisé en ce que, pour l'introduction des gaz à teneur élevée en oxygène, des tubes partant des parois latérales du four d'allumage pénètrent pratiquement horizontalement dans la zone inférieure de celui-ci et sont munies de buses dirigées obliquement ou verticalement vers le bas.
16. Dispositif selon l'une des revendications 10, 13 et 15, caractérisé par un dôme d'isolation thermique (20) se raccordant directement au four d'allumage, muni de parois thermiquement isolantes (30, 32, 36, 38), lequel dôme est ouvert vers le bas en direction de la machine à fritter, et dont les parois latérales (36) et les parois frontales (30, 32) s'étendent jusque tout près du mélange de frittage et dont le toit (38) présente des perforations (44) pour l'aspiration d'air comburant.
17. Dispositif selon la revendication 16, caractérisé en ce que la grandeur des perforations (44) destinées à l'air comburant est réglable.
18. Dispositif selon l'une des revendications 16 ou 17, caractérisé en ce que le toit est formé de parties fixes (40) qui s'étendent dans la direction longitudinale du dôme et de parties (42) pouvant se déplacer vers le haut et vers le bas qui ont une plus grande surface que les lacunes entre les parties fixes (40), de sorte qu'elles chevauchent les parties fixes, et qui sont suspendues, de manière à pouvoir se déplacer, pratiquement verticalement, sur un support pouvant se déplacer vers le haut et vers le bas.
19. Dispositif selon l'une des revendications 16 à 18, caractérisé en ce que le dôme thermiquement isolant (20) est subdivisé en une pluralité de segments, de sorte que l'on peut faire varier sa longueur selon les exigences.
EP81101962A 1980-03-21 1981-03-17 Procédé et dispositif pour allumer un mélange à fritter Expired EP0036609B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81101962T ATE4916T1 (de) 1980-03-21 1981-03-17 Verfahren und vorrichtung zum zuenden eines sintergemisches.

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE3010844A DE3010844C2 (de) 1980-03-21 1980-03-21 Zündofen
DE19803010845 DE3010845C2 (de) 1980-03-21 1980-03-21 Thermo-Isolierhaube für Sintermaschine
DE3010845 1980-03-21
DE3010844 1980-03-21

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EP0036609A1 EP0036609A1 (fr) 1981-09-30
EP0036609B1 true EP0036609B1 (fr) 1983-10-05

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EP (1) EP0036609B1 (fr)
JP (1) JPS5911649B2 (fr)
BR (1) BR8108753A (fr)
CA (1) CA1151420A (fr)
DD (1) DD157576A5 (fr)
DE (1) DE3161084D1 (fr)
ES (1) ES500494A0 (fr)
PL (1) PL134440B1 (fr)
WO (1) WO1981002747A1 (fr)
YU (2) YU70581A (fr)

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US4600438A (en) * 1983-03-09 1986-07-15 Texas Industries, Inc. Co-production of cementitious products
FR2588069B1 (fr) * 1985-09-30 1989-08-25 Stein Heurtey Procede d'allumage d'un lit de minerai en vue de son agglomeration
FR2670801B1 (fr) * 1990-12-20 1994-07-01 Lorraine Laminage Dispositif d'allumage d'un lit de melange de materiaux tels que du minerai et du coke.
ZA922100B (en) * 1991-03-26 1992-11-25 Samancor Ltd Infra red ignition method for ore sintering process
DE102011110842A1 (de) * 2011-08-23 2013-02-28 Outotec Oyj Vorrichtung und Verfahren zur thermischen Behandlung von stückigem oder agglomeriertem Material
CN103017528B (zh) * 2012-12-19 2015-03-11 中冶长天国际工程有限责任公司 用于烧结点火炉的微压调节系统
CN104457255B (zh) * 2014-12-02 2016-04-20 中冶长天国际工程有限责任公司 烧结点火炉及其调整方法
CN104807326B (zh) * 2015-05-11 2016-09-14 马钢(集团)控股有限公司 一种适应料面波动的烧结点火炉及其使用方法
CN112626297A (zh) * 2020-12-15 2021-04-09 赵辉 一种高炉检修用点火装置
JP7794165B2 (ja) * 2023-04-20 2026-01-06 Ｊｆｅスチール株式会社 点火炉、焼結機、点火炉の制御方法、焼結鉱の製造方法および点火炉における装入層の温度測定方法

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US2402339A (en) * 1943-03-31 1946-06-18 Republic Steel Corp Ignition furnace for sintering machines
DE1051251B (de) * 1957-11-05 1959-02-26 Metallgesellschaft Ag Verfahren zur Durchfuehrung endothermer Prozesse auf dem Sinterband
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DD157576A5 (de) 1982-11-17
ES8202423A1 (es) 1982-02-01
JPS5911649B2 (ja) 1984-03-16
PL134440B1 (en) 1985-08-31
DE3161084D1 (en) 1983-11-10
JPS57500154A (fr) 1982-01-28
US4443184A (en) 1984-04-17
ES500494A0 (es) 1982-02-01
EP0036609A1 (fr) 1981-09-30
CA1151420A (fr) 1983-08-09
YU83183A (en) 1984-06-30
YU70581A (en) 1983-09-30
BR8108753A (pt) 1982-07-06
PL230262A1 (fr) 1982-02-01
WO1981002747A1 (fr) 1981-10-01

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