BE522882A - - Google Patents

Description

       

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   KO-WE NIEDERSCHACHTOFEN-GESELLSCHAFT, m.b.H., residing in BAD GODESBERG (Germany).



   COMBINED SYSTEM OF TANK OVEN AND FIREPLACE.



   The present invention relates to combined shaft furnace systems (eg blast furnace, low shaft furnace, casting generator) with a hearth (eg steam boiler, flue gas-heated boiler, furnace. industrial gas burner), which, in addition to increased production capacity, also have, as technical advantages, the possibility of obtaining high-value products, such as metals (for example iron), use of coal with a high ash content and a low ash melting point, and the elimination of work with old-fashioned.

   The invention essentially consists in using, as the heating installation for the hearth, a shaft furnace (for example blast furnace, low-chamber furnace, casting generator), directly connected to it and serving at the same time in obtaining metal (eg iron).



   Several exemplary embodiments of the combined system forming the subject of the invention and methods for using this combined system are described below.



   The first exemplary embodiment consists of a combination of a particular kind of a metal casting generator with a steam boiler and has the following characteristics, separately or in combination;
1. The casting generator has a rectangular horizontal cross section. 11 is joined by construction to the boiler so as to constitute with the latter a single whole, so that it has a wall in common with the boiler. combustion chamber of the boiler. The generator normally runs the full width of the boiler wall.



     2. The blowing nozzles for the combustion air are arranged in a horizontal row on the side of the generator away from the boiler.



   3.The diameter of the generator work, i.e. the distance of the nozzle orifice from the opposite wall, is a little higher.

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 greater than the penetration depth of the blown air. It is generally between 1 m and 1.5 m.



     4 'Preheated combustion air is blown in. The preheating is advantageously all the stronger the higher the ash content of the coal.



   5. Casting generators are normally operated with steam blowing, to utilize the excess heat from the formation of CO by the decomposition of steam and to obtain, with a relatively thin layer of coal, as low a temperature as possible of the top gas.

   This method of using excess heat from the gasification operation is deliberately waived, and with advantages, in the present combination. The decomposition of water vapor is related to the high loss. energy of the heat of vaporization of water, which, referred to the stoichiometric equation of the reaction, amounts to approximately 25% of the quantity of heat employed (see the following equations: )
C + H2O (as water vapor) = CO + H2O- 31.6 Kcal
C + H2O (in liquid state) = CO + H2 - 41.6 Kcal.



  For this reason, it is fundamentally fairer to use, as such, the heat given off by gasification of coal with oxygen or air, and this is one of the great advantages of the combined process. mentioned to allow the direct use of the heat of gasification. The heat released by gasification is contained for the smallest part in the fluid slag and, for the greater part, in the gases rising in the tank of the generator. In the casting generator working in combination with a boiler, both quantities of heat can be used in a simple and direct way for heating the boiler.



   With regard to the heat contained in the gases, this takes place by keeping the carbon layer as thin as necessary in the interest of a complete transformation of oxygen into CO2. and carbonic acid to CO. The height of the carbon layer above the level of the nozzles is thus most of the time not more than about 2 m. The gas, leaving this layer of coal after having crossed it, has a high temperature and is blown, with this temperature, directly into the combustion chamber of the boiler, where it burns, with the combustion air , also previously heated, with a very hot flame, so that the production capacities of the boiler obtained per unit of heating surface are unusually high.



   6. To allow the high temperatures to exit the gas from the gasification apparatus, it is advantageous to preheat the coal before it enters the gasification zone. It is particularly advantageous to combine this preheating with slow distillation of the fuel, in order to be able to recover the bitumen as a distillation tar and to be able to sell it as a high value by-product.



  A slow distillation and preheating chamber is therefore arranged in front of the gasification chamber of the casting generator. From the gas produced in the gasification chamber, a partial stream is diverted and passed through the slow distillation and preheating chamber. This partial stream of sweep gas, cooled to low temperature, contains, after leaving the generator, the tar vapors. These are collected in a known manner and the sweep gas, enriched with the high calorific value slow distillation gas, is burned in the combustion chamber of the boiler.



   7. Care must be taken that there is no negative pressure anywhere in the generator. The pressure conditions in the combined generator and boiler system can be excellently adjusted without leaving

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 The heating gas does not pass freely from the generator chamber into the combustion chamber of the boiler, but retains this gas by an intermediate device in the form of a nozzle. This arrangement has the advantage that the pressure level is raised throughout the generator, so that one can walk under pressure through the whole slow distillation chamber and that one can, at the top, still obtain by setting any desired overpressure.

   It is advantageous in certain circumstances to run the whole generator under a slightly increased pressure, because it is thus possible to increase appreciably the production per m2 of cross-section of the tank, as one shows tests at the top. furnace. The increase in pressure in the generator via the passage nozzle has the additional advantage that, in the case of a suitable embodiment of the nozzle, it is possible to obtain a rapid mixing of the gas from the nozzle. heating with combustion air and thus a short hot flame.



   8. The necessary height of the carbon bed in the generator depends on the reactive power of the carbon. It is therefore necessary to be able to adjust the height of the carbon bed. This can be done, for example, by arranging, the place where the coal passes from the pre-heating and slow distillation chamber into the gasification chamber, a register-like regulating member.



   9. A metal casting generator, working in combination with a boiler, can by the inherent nature of this combination also be easily adapted to the use of sticky coal. Although, in the case of coals with a high ash content, the bonding property does not normally cause the same difficulties as in the case of coals with a low ash content, this fact however also underlines the advantageous character of the combination mentioned.

   Indeed, the fact that the gases, leaving the gasification chamber, are very strongly heated, allows the following operating mode: the coals are, in the pre-heating and slow distillation chamber, only heated up to- below the temperature of the onset of agglutination and are, in this state, spread periodically in a thin layer on the hot surface of the carbon in the gasification chamber. The heating, especially of the outer zone of the pieces of coal, beyond the coking temperature, takes place here so rapidly that any agglutination, which hinders the gasification operation, is avoided.
10.

   A particular point in the proposed combined process lies in the fact that during the gasification of coal with a high ash content, large amounts of liquid slag are formed. of slag, to think that the slag, which is introduced into the generator in the form of ash, entails exactly the same costs as coal. Especially in a very hot state, it constitutes a material which entails high costs. One must therefore endeavor to transform the slag into products which can be sold.

   The prospects of obtaining such slag-based products are, when obtained in a fluid state, much more favorable than when the slag is obtained in inhomogeneous, practically unusable form, as in the case of stoves grate or pulverized fuel hearths, - or else these prospects exist only in the case of obtaining slag in the fluid state. Such slag-based products, which can under certain circumstances be transformed by specific additives, are slag bricks, slag sand, slag wool and especially cement.



  It has already been found on several occasions that coal ash has hydraulic properties. However, the use of this fact for the cement industry has hitherto only been possible to a limited extent, because the composition of this ash (which mainly comes from pulverized charcoal stoves) was too uneven. . In the metal casting generator, a completely homogeneous slag product is obtained, which can be transformed, by suitable additions, exactly into a raw material for the cement industry. It is furthermore possible, by the addition of quan-

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 Suitable tities of lime to carbon gasification, directly obtain molten cement in the casting generator.

   This molten cement constitutes a particularly high value use method of the collected slag, and the product obtained constitutes a high profit item for the generator. In this procedure, of course, care must be taken that the temperature in the generator structure is high enough to reach the free-flowing temperature of the cement slag. The means to be employed for this purpose are the preliminary heating of the air and, in certain circumstances, the use of air enriched with oxygen.

   In the case of the use of oxygen, it is advantageous, in order to keep the proportion of the latter as small as possible, to arrange, below the level of the air blowing nozzles, nozzles by which a small amount of oxygen is blown in, which only serves to achieve the additional increase in temperature to make the slag well fluid.



     11. The amount of heat contained in the slag fluid is only a small fraction of the calorific value of coal. Even when the ash content of the coal is 25%, the heat contained in the slag is barely 3% of the heat given off by the combustion of the coal. It may, it is true, in the case of higher contents of the charcoal ashes, be of some importance that the slag is cooled in the combustion chamber, in a suitable place, by a device taking into account the obtaining The slag cooling can also be used in a particularly simple way to preheat the air.



   12. The operation of metal-casting generators with coal as fuel causes difficulties in the case of certain coals. This is particularly the case when the coal, on heating, breaks up into a fine coke. A not very fluid mixture of coke and ash then occurs in the work of the generator, which leads to adhesions and makes it impossible to flow the slag. In such cases, it has been recognized that an excellent way to ensure trouble-free operation of the furnace is to mix iron ore with gasification coal.

   The iron oxide dissolved in the slag reacts with the fine particles of carbon included in the slag, which cannot be reached by the blown oxygen, due to the slag envelope which surrounds them, but which are necessarily attacked by the oxygen of the ore.



  The danger of the formation of a not very fluid mixture of slag and coal in the work of the generator is naturally all the greater as the content of the coal in ash is higher, so that the addition of the mine - charcoal spoke constitutes in this case an important measure to ensure a functioning of the furnace free of disturbances. Many coal ash by itself contains fairly large amounts of iron oxide, so that it does not require or require only a small addition of ore. It can however be considered, as a particular advantage of the gasification of coal in the casting generator, that the iron oxide introduced is reduced and constitutes, in the form of cast iron, an important item to be credited to the generator.



   The advantages of the device described in points 1) to 12) for the use of ash-rich coal for heating boilers are, compared to other known devices, the following: operation free of faults even in the case of a high ash content; unburned coal residue in the ashes; maximum production for a small footprint; simple and inexpensive construction of the installation; high flame temperatures in the combustion chamber of the boiler; obtaining high value by-products.



   In the accompanying drawings, fig. 1 schematically represents a gasification installation for a boiler hearth.



   A designates the casting generator, and B the combustion chamber of

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 Boiler. 1 designates the generator charging device, into which the coal and, in certain circumstances, the additive materials are charged. 2 designates the discharge port for the scavenging gas, which is enriched with tar vapors released from the coal by slow distillation of that = cio The scavenging gas is, after separation of the slow distillation tar, blown into a suitable place in the combustion chamber of the boiler. 3 denotes the heating and slow distillation chamber, through which the hot purge gas passes.

   This scavenging gas is formed by a partial stream of the gas formed in the gasification chamber. 4 denotes the gasification chamber, from which most of the gas formed flows in the hot state into the chamber. combustion chamber, while a small part of it is passed, as purge gas, through the heating and slow distillation chamber of the generator. 5 denotes the blowing nozzles for the supply air. gasification. 6 designates 1 * outlet for the fluid slag, which in the example considered is passed into the combustion chamber of the boiler for its cooling. 7 designates the tap hole for the formed iron.

   The passage of the coal from the slow distillation chamber into the gasification chamber is regulated by a register 8, which can be moved in height, so that the height of the fuel bed can be adjusted in the gasification chamber corresponding to the reaction capacity of the coal. This damper 8 has openings for the passage of the purging gas. The combustion air and the heating gas are blown into the combustion chamber of the boiler by nozzle-shaped orifices 9 and 10. It is obvious that the combined system described can be applied to all apparatus which burns heating gas, for example gas heaters, hearth furnaces, calcination furnaces, etc. ..



   The second exemplary embodiment of the present invention is a combined system of a casting generator with a steam boiler, in which the casting generator is located so close to the boiler that the gas passes with the highest temperature. higher in the boiler, and the device for the admission of air, fuel and additives to the casting generator is on the side of the casting generator which is remote from the boiler. Already in the first exemplary embodiment, the combination of the casting generator with a steam boiler is made in such a way that they constitute a single complete whole.

   In the second embodiment, the following improvements are provided to further increase the production capacity:
The production capacity of a casting generator is normally, for a given fuel, a function of the cross section of the generator. One can, based on the practice of the blast furnace, build casting generators with a diameter of several meters. But, in the combined generator and boiler system, it is disadvantageous to make the generator wider than about 1.5-2m.

   Indeed, as the height of the fuel above the level of the nozzles is normally between 1 and 2 m, it would be necessary, with larger widths of the generator, to count with nozzles ensuring a blowing from side to side. apart from the fact that, for an increasing width, the necessary blowing pressure for the wind increases sharply. In order to achieve, despite the relatively small width of the generator, sufficient gasification capacities for modern boilers with high steam production, a series of new operating characteristics are planned:
1.

   For a given cross section of the structure, a casting generator can be charged to a height that is greater the more gas, flowing upward through the charge, is more evenly distributed over the total cross section. generator. For the same layer height over the entire cross section of the generator and for a uniform distribution of grain sizes over the entire cross section,

   the gas flow velocity is maximum along the wall of the generator in which the blowing nozzles are placed and this velocity decreases to

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 as one moves away from the orifice of the blowing nozzles o It is only after the gas has made a path of several meters upwards through the charge that a progressive equalization of the speed occurs gas flow over the entire cross section of the generator.

   To achieve this equalization as quickly as possible, also for the low heights of the load in the generator combined with the boiler, this generator is loaded on the side corresponding to the blowing nozzles, so that an embankment occurs. of the load according to the angle of the natural landslide slope and that the slope of the slope decreases from the side of the generator corresponding to the blast nozzles to the side of the generator facing the boiler. With this arrangement, two effects occur which exert an equalizing action on the flow of gas in the charge. The large pieces in the charge roll down the slope and make the side of the generator that is away from the blast nozzles more gas permeable.

   The distance of the blowing nozzles from the surface of the load becomes of the same magnitude at all points thereof. Further, a large gas exit area is formed from the feed, resulting in lower gas exit velocity with reduced dust loss.



   2. In the case of limiting the width of the generator to approximately 2 m, the surface of the generator, to be placed on the front of the boiler, is not sufficient, - in certain circumstances, in particular in the case of the case of coals which are not very reactive and rich in inert constituents, - to supply the boiler with sufficient quantities of heating gas.

   In this case, the generator is given, in accordance with the invention, in the following manner, the surface necessary to supply the boiler with heating gas: Solution a: Instead of the straight front wall, with a section rectangular cross section of the generator associated therewith by construction, the boiler is given a curved front wall up to a circular shape, so that, in the limiting case, the cross section of the generator has the shape of 'a circular half-ring. The cross section of the generator thus obtained is, for the same width of the boiler, a multiple of the area obtainable in the case where the boiler is limited by straight lines in cross section.



    Solution b: casting generator not only extends along one wall of the boiler, but limits the boiler to several sides a If one side of the boiler remains free, the cross section of the generator can advantageously also have the shape of 'U. In the extreme case, for boilers with very high production capacity, the boiler is limited on all four sides by the casting generator. In this case, the axial space, left free by the generator for the boiler, can also be circular.



  Solution c: The boiler is built directly above the casting generator, which in this case is advantageously circular in shape and large in diameter. Charging takes place at the periphery of the generator, so that a hopper-shaped bed of fuel occurs. Secondary air is blown into the space above the fuel bed; under certain circumstances a controlled flow is advantageous in this space, for example circular in shape. To reduce the gas outlet speed and the loss of dust, the generator can also be widened upwards in the form of a hopper.



   3. In accordance with the invention, it is possible to achieve a significant additional increase in production by increasing the pressure in the system. The advantages of such an increase in production have already been used in the first embodiment. pressure beyond the pressures normally existing at the outlet of the generator;

   the pressure value was to be used, in the case of insufflation in the combustion chamber of the

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 boiler by a nozzle or by a burner, to achieve rapid combustion. It is now recognized that it is advantageous in certain circumstances to raise the pressure level in the entire boiler system. This is because the heat transfer phenomena in the boiler are significantly increased in certain circumstances. In such cases, a turbine driven by the burnt gases is placed behind the boiler.



   In the third exemplary embodiment of the invention, there is a combined system of a shaft furnace and of a steam boiler, in which the gas produced in the shaft furnace is supplied to the combustion chamber d. In a steam boiler, the solids contained in the gas are brought to a liquid state by complete melting in the steam boiler and are separated from the flue gas in this form.



   A steam boiler combined with a shaft furnace must burn and use the hot top gas and in some cases enriched with tarry constituents o The shaft oven and the steam boiler combined with each other are, in the third embodiment, described below, arranged with respect to each other in such a way that the difficulties which arise separately in each system are avoided by the use of such a combination.

   It has in fact been observed that the operating conditions of a shaft furnace are improved quite remarkably when one has behind this shaft furnace, not an ordinary boiler, but a chamber boiler. smelting, or other boiler in which the solids contained in the flue gases are separated in a state of complete fusion and are recovered o Important steps in the construction and operation of a shaft furnace, in particular of such a furnace used for the treatment of iron ores, have hitherto been taken in order to obtain a top gas as low as possible in dust. In most furnaces, production is limited by the high content top gas in dust, which occurs in the case of increased production;

   this high dust content loads the dust separators behind the furnace and raises the problem of using the dust from the top gas. On the other hand, it is an operating characteristic of melting chamber boilers that it is possible to overcome even very high dust contents in the combustion gas, as they occur in the case of combustion. the combustion of a coal with inert constituents with an ash content of 40 to 50%, by melting the dust in the melting chamber. It has even been found that such melting chambers work more unfavorably with a low dust content in the flue gas than with a higher dust content.

   According to the invention, the shaft furnace is therefore combined, without the interposition of any dust removal device, directly with a melting chamber boiler.



   The melting chamber of the boiler, in the case of this embodiment, simultaneously plays the role of an apparatus for collecting dust from the throat. The dust from the top is, as long as it does not consist of fuel, = which is burnt in the melting chamber, which is an additional advantage, - separated in the liquid state and discharged from the melting chamber at the liquid state. This melt is, as long as there is no other new use, cooled in the form of pieces and is added again to the melt bed of the shaft furnace.

   This transformation in the form of pieces can take place in the simplest case by granulation of the melt in water; but cooling can also be effected by slower solidification into larger sized pieces or plates, which are then broken up to the size required for the shaft furnace.



   An important additional embodiment of the combined shaft furnace and melting chamber boiler system is the use of the melting chamber for the smelting of ore dust. It is known that one cannot that it is very difficult to operate shaft furnaces with pulverulent raw materials, in particular with ores

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 In any case, a relatively low dust content in the melting bed cannot be exceeded. In the case of a high dust content in the melting bed, the production of the furnace is always limited by the need to maintain a low speed of the gas at the top.

   Many iron ores are obtained predominantly in pulverulent form or have a higher dust content than the shaft furnace can withstand. Until now, care has been taken to bring the fine ore in the form of lumps, at additional expense, by sintering, agglomeration in the form of balls or briquettes. One can consider as a very favorable solution the fact that one is able to bring the fine ore to the liquid state in the melting chamber of the steam boiler and to obtain, from the melt, in a simple way, a lumpy product, which can be added to the melting bed of the shaft furnace.



   In the simplest case, the fine ore is introduced into the shaft furnace with the rest of the smelting bed; the shaft furnace is thus operated with a high production and, due to the corresponding high speed of the gas at the top, is allowed to entrain a large part of the pulverulent constituents with the top gas and pass into the melting chamber. since these are predominantly pulverulent ores, it may also be more favorable to blow these directly for their fusion in the melting chamber.



   In order to achieve the melting effect in the melting chamber also in the case of higher dust contents and a relatively low top gas temperature, it is, in certain circumstances, necessary to provide special measures for increase the combustion temperature in the melting chamber. This can be effectively obtained by raising the temperature of the combustion air, to be blown into the melting chamber, beyond the air temperature usually adopted in boilers of this type. , for example to 5000 and more.



  In this case, the boiler is fitted not only with the usual air heater, but also with a hot air tube appliance. In this case, it may be advantageous to heat both the wind for the shaft furnace and the air for the melting chamber in a hot-air tube appliance mounted after the boiler. The temperature rise in the melting chamber consists in the use of additional heating agents, which are burnt alongside the top gas in the melting chamber, for example coal dust or carbon. oil. Such additional heating can also play an important role in the equalization of the heat input, varying in certain circumstances, for the boiler due to variations in the operation of the shaft furnace.



   In the case of high melting point ore dusts, it is further advantageous to additionally introduce, into the melting chamber, melting agents, which produce a lower melting temperature, for example CaO or Si02, depending on the composition of the melt. It is also particularly advantageous to introduce the lime necessary for the metallurgical operation, in the form of powdery limestone, into the melting chamber, since the operation in the shaft furnace is thus dispensed with the quantity of heat, which is important in certain circumstances, which is necessary for the neutralization of the acidity of limestone.



   Fig. 2 of the accompanying drawings shows by way of example a combination according to the invention between a shaft furnace and a melting chamber boiler. 11 designates the shaft furnace with the duct 12 for supplying the wind and the device 13 for loading the top. 14 designates the pipes for supplying gas from the top to the boiler. 15 denotes the melting chamber of the boiler with the burners 16. The melting chamber is surrounded, in the usual way, by vaporization tubes, which are coated with a protective material, for example refractory clay. At its lower end, the melting chamber has an orifice 17 for the discharge of the liquid melt.

   Following the fusion chamber are

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 mounted the superheater 18 and the hot-air tube device 19 for the heating of the wind for the shaft furnace In the path of the flue gases are also interposed, as the temperature drops, a heater preliminary 20, a steel economizer 21, a cast iron economizer
22 and the heater 23 for the pre-heating of the combustion air for the melting chamber and for the pre-heating of the wind for the shaft furnace.



   The fourth exemplary embodiment of the present invention described below constitutes a variant of the third exemplary embodiment and is characterized essentially by the fact that, in addition to the device for combustion, it is provided in the steam boiler. top gas from the shaft furnace, again a device for the combustion of a second fuel, for example pulverized coal
The procedure, with a combined shaft furnace and steam boiler system according to this embodiment, assumes that the combustion temperature in the combustion chamber of the boiler is high enough to achieve complete melting of the gases. solid constituents.



   As a means of achieving a sufficient combustion temperature, it has heretofore been proposed to preheat, to a suitable high degree, the combustion air for the steam boiler, as well as to work with a high temperature of the combustion gas. top of the shaft furnace. The present invention proposes to provide the technique, - for certain operating conditions of the shaft furnace, which make it difficult or impossible to use the means indicated, - an additional measure making it possible to achieve the desired aim.

   In the case of certain operating conditions of the low-shaft furnace, - for example when as much iron as possible has to be extracted per unit of loaded coal, - it is in fact not possible to walking with a high temperature of the top gas; in addition, the calorific value of the top gas decreases in the case of such an operating mode. The result of these two circumstances is that a sufficiently high combustion temperature of the flue gas can only be reached with prior reheating, to a non-aconcmically high degree, of the combustion air. of the fusion bed in H20 and CO2 acts in the same direction.

   In accordance with the invention, in such cases, a secondary fuel is also burned in the combustion chamber of the boiler, in addition to the top gas. Suitable such secondary fuels are gaseous substances, liquid or solid, which, by themselves, on burning with preheated air, give a higher combustion temperature than that necessary to produce the fusion of the solid constituents. Gueulardo gas It appears particularly advantageous to provide for this purpose additional heating with pulverized coal for the combustion chamber of the boiler. The use and provision of additional pulverized coal heating is, for still other reasons, an important additional measure for the combined shaft furnace and steam boiler system.

   The shaft furnace works best with a grain material, the dust content of which should not exceed a certain upper limit, for example 20%. If fine coal with a grain size of 0 - 10 mm is fed to a combined shaft furnace and steam boiler system, it is advantageous in accordance with the present invention to charge the fine coal. with a grain size of 3-10 mm in the low-chamber furnace and to use fine charcoal with a grain size of less than 3 mm, if necessary after additional division, for the auxiliary heating of Boiler.



   The use, according to the invention, of the aforementioned auxiliary heating of the boiler makes it possible to achieve a further object, namely, to eliminate an important fundamental difficulty of the combined system of a shaft furnace and of a steam boiler, which difficulty arises. present when high-value products, for example casting melt, are to be melted in the low-shaft furnace. The energy offtake is in fact generally subject to variations, which are normally equalized, on the side of the va-

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 fear, by adjusting the quantity of fuel and the quantity of combustion air. This permanent and extensive adjustment would be difficult to achieve in the case of a combined system of a shaft furnace and steam boiler, if it is necessary to obtain a melted product of uniform high value.

   Frequent variations in the amount of wind, which is normally the easy to adjust component in the operation of the low shaft furnace, prevent uniform operation of the furnace. Under these conditions, the mentioned use of an auxiliary fuel in the steam boiler means a complete elimination of the mentioned difficulties. The adjustment of the heat input into the steam boiler takes place, according to the invention, by metering the secondary fuel, for example pulverized coal and its combustion air. The low-shaft furnace works, in the case of this mode of operation according to the invention, permanently with a uniform load and is therefore able to give a high-value, uniform melt.



   In the fifth exemplary embodiment of the present invention, there is a method of operating a shaft furnace (for example a blast furnace or a low shaft furnace or a shaft furnace. casting generator) with liquid casting in combination with a furnace (for example a steam boiler), in which the production of iron is notably reduced in the case of operation as a shaft furnace, or is increased in the case of operation. - ment as a casting generator.

   The advantages achievable by the process according to the invention appear from the following description, which at the same time explains the differences between the new process and the known processes.
There are known liquid-casting shaft furnaces products not evacuated in the gaseous state, shaft furnaces whose main purpose is to produce, from the loaded fuel, a gas of as high a value as possible.



  This gas is brought, purified or uncleaned, in the hot or cold state, to a hearth (for example a steam boiler or an industrial furnace) to be burnt there. The purpose of this combustion and in particular the efficiency of the combustion process makes it necessary for the gas produced in the shaft furnace to reach the hearth with as high a calorific power as possible. Such shaft furnaces, used for the production of gas, are generally called flow generators. In order to be able to carry out the operation in the shaft furnace with liquid casting without difficulty, fluxes, such as lime, slag, iron ore and others, are added to the fuel.

   By means of these fluxes, the high melting point of the coal ash is lowered to a permissible degree, so that the slag can be poured out of the furnace without difficulty. In this mode of operation of the casting generators, one always obtains also small quantities of liquid iron, which are poured with the slag. This iron comes in part from the iron contained in the ashes of the coal and, in part, from the iron contained in the added fluxes. It would easily come to mind to increase the amount of iron extracted by the casting generator operation, by increasing the addition of ore to the fuel, to achieve greater economy of operation. But this measure cannot normally be applied, because it would result in a noticeable deterioration of the gas.

   In fact, for the reduction of ore, a large consumption of heat is required, so that the calorific power of the gas produced decreases to the extent that the calorific power of the fuel is used for the reduction of the ore.



   Also known are furnaces with liquid casting and general use, in which the main aim is to obtain as large a quantity as possible of iron per unit of fuel loaded. It naturally results from this problem that the gas, collected in this operation as a by-product, has only a relatively low heat output and is of relatively low value as a gaseous fuel. Such gases cannot, in many industrial furnaces, be used because of their low calorific power, and their combustion in a steam boiler is only possible in the purified state.

   It was indeed found

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 that it is advantageous, owing to the high content of such top gas from shaft furnaces in relatively low melting point dust, to carry out the combustion at a temperature above the melting point of the dust, in a melting chamber boiler. But this supposes @ that the calorific power of the gas is sufficiently high to reach, taking into account the pre-heating of the air, the necessary combustion temperature. of a gas with a lower calorific power to burn, such as for example top gas from the blast furnace - prototype of a shaft furnace mainly used for the metallurgical treatment of ore -, the gas must normally, before combustion,

   be free of the dust contained in it, because in this way only safe combustion is possible in a boiler without obtaining, in the state of complete fusion, the dust contained in the gas. The casting generator and the blast furnace are the types of shaft furnaces, one suitable for gas production and the other for metallurgical processing. One of the products - gas or iron - is the main product, the other is the by-product.



   The present invention relates to a novel embodiment of the shaft furnace operation to be carried out with fuel, iron ore and, in certain circumstances, with additives, operation in in which the two products - gas and iron - constitute principal products of approximately equal rank.

   The operation according to the invention therefore represents a mode of operation in which gas is not produced as good as in the actual operation of the casting generator and as much iron is not produced as in the metallurgical treatment proper. said - for example in the blast furnace, - but in which the quality of the gas is still sufficient to allow, for example, direct combustion of the hot unclean gas in the melting chamber boiler and in which the quantity of iron per tonne of fuel loaded is still so great that it has a decisive influence on the economy of the entire operation. Depending on the type of shaft furnace used - casting generator on the one hand, or blast furnace or low vessel furnace, on the other hand,

   the process according to the invention constitutes the operation of a casting generator with significantly increased production of iron or the operation of a blast furnace or low-shaft furnace with reduced production of iron * In the sense of the assessment adopted, up to 'here on the operation of a casting generator or of a blast furnace or low-vessel furnace, the previous definition of the process according to the invention appears as a paradox, which already makes it possible to recognize the particular type of the problem posed and solved in accordance with the present invention.



   The present invention has particular significance for the operation of a shaft furnace, in the event that ore poor in iron is to be processed. Such iron-poor ores, for example with a content of about 25% iron, were heretofore, in the normal blast-furnace metallurgical process, mixed with relatively small amounts of richer ores, because the exclusive use of iron-poor minerals in the metallurgical treatment process employed heretofore resulted in too high a fuel consumption and was therefore uneconomical.

   The surprising observation was made that it is possible, in the process according to the invention, by the combination of a shaft furnace with a boiler, to treat iron ores with, for example, only 25% iron, without addition of ores richer in iron, directly and with a high economic return. It is particularly surprising that the further aggravating condition of employing coal with a high ash content as fuel can be further satisfied. It would be completely impossible to do under these conditions simultaneously in the normal operation of metallurgical treatment in the blast furnace or in the low-shaft furnace, from an economic point of view.

   By the metallurgical treatment process according to the invention, on the other hand, it is possible to observe for example with the best result the following operating conditions:
The fuel consists of coal with an ash content

 <Desc / Clms Page number 12>

 by 25%. Ore with an iron content of about 25% is mixed with the coal. The preparation of the smelting bed is carried out in such a way that, on the one hand, there is about 300 kg of iron per tonne of coal loaded and that, on the other hand, one obtains, as far as possible without other additive substances, from the ashes of the coal and the gangue of the ore, a favorable flow of the slag.

   The height of the charge in the shaft furnace is kept so low - for example 1.5 to 2 m - that the top gas passes, with a temperature of about 700 to 800 C in the combustion chamber of the tank. steam boiler. The grain size of the ore bed is determined in such a way - for example the majority of these grains having from 20 to 40 mm - that there occurs as little change as possible of the calorific power by transformation of CO into CO2 from the decomposition of iron ore in the upper part of the shaft furnace.



   The previous exemplary embodiment shows that the process according to the invention, as regards the layer height in the furnace, the size of the grains of the fusion bed, the fuel consumption and the type of fuel per tonne of iron. , etc., departs completely from the mode of operation of known metallurgical processes.

   The fact that despite this a high economic yield is obtained is due to the fact that, in this metallurgical process, raw materials of lower value are used and that, contrary to the normal metallurgical process, the residual heat, which, in this latter, appears predominantly as a negative quantity, is collected as a second by-product in the form of a gas of high calorific power or is already collected in the form of water vapor, when The combined system of shaft furnace and steam boiler as a single whole.



   Casting generators have also already been proposed in which the hot top gas is brought directly to a hearth or to a steam boiler to be burnt there. However, such solutions hardly offer any further advantages over the steam boiler with pulverized coal heating, which has now reached its full development, in particular over the coal-fired melting chamber boiler. sprayed. It is only by the fact that, in accordance with the present invention, this composite process has been transformed into a metallurgical operation with iron as the second main product that excellent economy has been obtained and thus the production. technical necessity of the practical application of the method according to the invention.



   The sixth exemplary embodiment of the present invention consists of a method for using the combinations described above of a shaft furnace with a hearth, when these are used for the metallurgical treatment of poor iron ores with rich gangue. in silica, and it consists in that, by applying the strongly acidic fusion process, coal rich in ash is used as fuel. The technical advantages which can be obtained with such a process result from the explanations below.



   A large part of iron ores has a low iron content, eg less than 30%, and a matrix rich in silica, eg 50% or more SiO2; It is therefore a very important problem to find the most advantageous possible metallurgical treatment from the technical point of view and at the same time economical of such iron ores.



   Direct metallurgical treatment of the ores mentioned in the normal process in the shaft furnace, for example in the blast furnace, is possible; however, in order to achieve proper slag flow it requires additives which in many cases render the procedure uneconomical. For example, ores with a normal slag index (CaO: SiO2 = 1.2 to 1.4) can be treated in a blast furnace, but so much lime has to be added that a very high fuel consumption becomes necessary. sary.

   Even in the case of the formation of an acid slag (slag index 0.9 to 1.1), the consumption of lime and hence also the consumption of

 <Desc / Clms Page number 13>

 fuel are still so high that an economical metallurgical treatment of acidic and poor iron ores is only possible with this procedure under other particularly favorable circumstances.



   Finally, it has been carried out, for ores of this kind, the very acid smelting process, in which the slag index is so strongly reduced (0.3 to 0.5) that it comes out. essentially without the addition of lime. However, in order to be able to melt such slag in a shaft furnace, one has to overcome a major difficulty. Slag rich in silica is, at normal temperatures in the work of a shaft furnace, relatively viscous, so that the casting these from the furnace is difficult or even impossible.



   It has been found that such slags become sufficiently fluid when they have a higher content of FeO (about 3-5%) and alkalis (more than 20%). The highly acidic smelting process is therefore carried out, in its normal embodiment, by adding alkalis (for example soda ash slag) to the smelting bed, and thus regulating a determined slag content in alkalis. This need for the addition of alkalis to the fusion bed limits the economic possibilities of the highly acidic smelting process, at least for ores poor in iron, since the relatively large quantity of slag resulting from the large proportion of gangue requires, besides a corresponding high fuel consumption, also a significant addition of alkalis.



   It has hitherto been of the opinion that such poor iron ores should be treated with a fuel as low as possible in ash, so as not to increase the large quantity of slag, coming from the ore. , still unnecessarily by the ashes of the fuel. But it has been made the surprising observation that, contrary to this rule followed hitherto, a particularly favorable metallurgical process is obtained when a poor iron ore is treated with a rich coal in ashes The ashes of coals from almost all known sources present, in fact, in addition to mostly significant quantities of iron oxides,

   a high proportion of alkali for the purpose in question This alkali content allows the formation of a very acidic slag in the shaft furnace operation with good slag fluidity properties, without adding alkalis from outside, as was necessary until now for this operation. But, as the proportion of alkalis in coal ash is mostly not more than 3-4% and rarely exceeds 5%, the apparently paradoxical measure mentioned above is advantageous, namely that high gangue ore must be treated with high ash coal, because only then can a sufficiently high alkali content be obtained in the resulting slag without addition of alkali from outside .

   For the metallurgical treatment process according to the invention, the general rule is thus obtained, which is in contradiction with all the principles hitherto recognized in metallurgical technique: the coal, used for the metallurgical treatment, should normally have an ash content all the higher as the iron ore is poorer, ie its gangue is richer in silica.



   The metallurgical treatment process according to the invention is explained for example by the following embodiment:
The carbon used for metallurgical treatment has, for example, the following composition (in the anhydrous state):
 EMI13.1
 
<tb> Pure <SEP> coal <SEP> 73 <SEP>% <SEP>
<tb> Ashes <SEP> 27 <SEP>% <SEP>
<tb>
<tb>
<tb> Coke <SEP> pure <SEP> 55 <SEP>% <SEP>
<tb> <SEP> content in <SEP> ash
<tb>
<tb> in <SEP> the <SEP> coke <SEP> 33 <SEP>% <SEP>
<tb>
 

 <Desc / Clms Page number 14>

 Ash analysis:
 EMI14.1
 
<tb> SiO2 <SEP> 47%
<tb>
<tb>
<tb>
<tb> Al2O3 <SEP> 31%
<tb>
<tb>
<tb>
<tb>
<tb> CaO <SEP> + <SEP> MgO <SEP> 5 <SEP>% <SEP>
<tb>
<tb>
<tb>
<tb> Fe203 <SEP> 13 <SEP>% <SEP>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Alkalis <SEP> 4%
<tb>
 
The ore to be treated has for example the following composition (in the anhydrous state):

   
 EMI14.2
 
<tb> SiO2 <SEP> 18 <SEP>%
<tb>
<tb> CaO <SEP> + <SEP> MgO <SEP> 8.5 <SEP>%
<tb>
<tb>
<tb> Al2O3 <SEP> 3.5 <SEP>%
<tb>
<tb>
<tb> Fe203 <SEP> 53 <SEP>%
<tb>
<tb>
<tb> Loss <SEP> at <SEP> fire <SEP> and
<tb>
<tb> others <SEP> 17 <SEP>%
<tb>
 
The raw materials mentioned above were combined in a shaft furnace melting bed, in accordance with the process according to the invention, so that a slag number (CaO + MgO) was obtained: SiO2 = 0 , About 3%. The alkali content represents about 2% of the slag.

   In such a slag, it is possible, without suffering losses of iron which adversely affect the economy, to allow the iron content to rise to 5% and more and thus obtain the advantage of further reduction. the viscosity of the slag, because the ashes or charcoal supply significant amounts of iron and compensate for the loss of iron in the slag.



   The metallurgical treatment according to the invention of low iron ores with a matrix rich in silica with coal rich in ash is moreover advantageously and to a large extent supplemented by the following characteristics of the invention. of slag resulting from this process, relative to the unit of iron extracted, is unusually high. In the previously mentioned example, the amount of slag is approximately equal to 1.5 times the amount of iron. This results in a relatively high consumption of coke in the furnace work, and there is a corresponding increase in the amount of top gas and the waste heat entrained by the top gas.

   According to the invention, this residual heat from the metallurgical operation is used for the same purpose, for which the thermal energy contained in the coal would otherwise be used. A high consumption of coke in the shaft furnace is obviously not detrimental to the economy of the process according to the invention, when the heat entrained by the top gas, which by far represents the most important station, is introduced. greater heat loss from the metallurgical operation, without losses to a steam boiler for steam production. In the application of this fundamental idea, the shaft furnace is therefore, in accordance with the invention, closely joined to a steam boiler so as to constitute organically a single whole.

   The top gas leaving the furnace is conveyed by short heat-insulated pipes to the combustion chamber of a steam boiler and is burned there with secondary air. It has been recognized as particularly advantageous to dispose the combustion chamber of a melting chamber boiler directly above the shaft furnace.



   Such a combined installation of a shaft furnace and of a

 <Desc / Clms Page number 15>

 Steam also works with excellent economic efficiency in the case of a relatively low production of iron per ton of coal loaded. It is possible, for example, in the procedure mentioned above, to prepare a smelting bed with approximately 850 kg of ores low in iron and rich in silica per 1 ton of coal rich in ash and thus obtain approximately
300 kg of iron per tonne of coal. The combination of the shaft furnace with the steam boiler ensures, in this case also, despite the relatively low proportion of iron, a high economic efficiency of the operation.



   In the seventh exemplary embodiment of the invention, the combined shaft furnace and steam boiler system is constructed such that at least the combustion chamber of the steam boiler is disposed above the furnace. shaft in the vicinity of the gas outlet opening (s), for example directly above the shaft furnace, and is connected to the gas collecting chamber of the shaft furnace by at least one gas supply (for example pipes or gas supply openings).

   This seventh example of an embodiment presents the following detailed construction:
A combined shaft furnace and steam boiler system, constructed in accordance with the invention, can, for example, be arranged in such a way that the combustion chamber of the boiler is arranged above the shaft furnace, but that, between the upper part of the furnace, constituting the gas collecting chamber, and the combustion chamber of the boiler, one or more substantially horizontal bottoms are provided, through which one or more tubes or openings for the passage of the gases allow the blowing of top gas into the combustion chamber of the boiler o Combustion air (secondary air)

   is added to the top gas advantageously on the path from the shaft furnace to the combustion chamber of the boiler or during blowing into this chamber, for example by means of a normal burner for the gas inlet and air to the boiler The above-mentioned combined shaft furnace and steam boiler system is characterized above all by the fact that, due to the rapid combustion of the hot top gas, it is only necessary to provide a relatively small combustion chamber for the boiler.

   It is therefore possible to develop the boiler, as a single flue boiler, only in height, without reaching an unacceptable construction height of the entire combined system, especially when the shaft furnace has itself a low loading height and therefore a construction height which is not too great. The shaft furnace with the single flue boiler built on top has the additional advantage of a minimum space requirement and complete freedom of the flue from the point of view of the location of the parts of the installation arranged before or after the combined system of shaft furnace and steam boiler.

   When the operation to be carried out in the shaft kiln requires a relatively large loading height, for example when, in the case of obtaining iron in the kiln vessel, it is necessary to achieve an indirect reduction of the ore as complete as possible, the greater height required of the shaft furnace may make it impossible to develop the entire boiler in height.



  In this case, it is advantageous to realize, according to the invention, the arrangement of the combined system of shaft furnace and steam boiler in such a way that, directly above the shaft oven, it is not located. essentially that the combustion chamber of the boiler, which is again separated in space, by intermediate bottoms, from the upper part of the furnace and which is connected to this upper part of the furnace by substantially vertical tubes.

   The remaining parts of the boiler are then in a descending flue, which is arranged next to the shaft furnace and which is only spaced from it at such a distance that operations in the shaft furnace can be carried out without being compromised by these parts of the combined system o It is also possible, from the combustion chamber of the boiler, to develop the boiler in a more horizontal direction in space, so that for example the entire boiler or as- large parts of it are placed on a platform located above the shaft furnace. Finally, for special reasons, for example

 <Desc / Clms Page number 16>

 when the loading devices so require, the combustion chamber can also be offset from the axis of the furnace.

   In this case, it is not necessary for the lower limit face of the steam boiler to be located above the plane of the top of the shaft furnace; but a very important feature of such an arrangement consists in that the combustion chamber of the steam boiler is arranged at a distance as small as possible from the tube or the gas outlet openings of the shaft furnace and s' adapts as fully as possible to this main condition by an appropriate shape and position in space. On this point as well as on other points, it is therefore always necessary to ensure that the detailed construction of the steam boiler and its development in a more vertical or more horizontal direction are voluntarily subordinated to the condition of coordination with the shaft oven.



   The construction according to the invention of a combined shaft furnace and steam boiler system allows - and this constitutes an additional important characteristic of the present invention - a particularly advantageous preheating of the wind, intended for the shaft furnace, in the chamber. steam boiler device. It is well known that the apparatus employed for preheating the wind, such as the Cowper, require for their operation a purified top gas to a great extent. Since, according to the invention, the pre-heating of the wind for the shaft furnace, as well as the pre-heating of the combustion air for the boiler are carried over to the last part of the boiler device, it is not necessary to It is not necessary to take into account the impurities contained in the gas.

   The pre-heating of the combustion air in the boiler is usually not increased above approx. 450 C. On the other hand, it is necessary in many cases to carry out the preliminary heating of the wind for the shaft furnace at a notably higher temperature. For this reason, it is advantageous to construct the preheater of the wind in such a way that the steam boiler provides two qualities of preheated air: one of the qualities, with a generally lower pressure. and a lower temperature, for the combustion chamber of the boiler a. steam, and the second quality, at higher pressure and higher temperature, like wind for the furnace.

   In addition, unlike the normal construction of boilers, it is foreseen to use for the temperature exchangers, for the preheating of the air, alloys corresponding to the higher temperatures.



   According to an additional feature of the present invention, use is made of the heat losses by cooling the shaft furnace for the production of steam, and corresponding members of the shaft furnace are interposed in the heat utilization system of the boiler. steamed. It is known that 3% and more of the useful heat of the fuel is lost by the cooling of the shaft furnace. This amount can be considerably reduced if, for example, the cooling of the tank and, in certain circumstances, the cooling of the shelves and the opening of the furnace are carried out by means of cooling elements with circulating water, including the circuit is connected to the boiler system.



   In a combined shaft furnace and steam boiler system it is necessary, under certain circumstances, - for example when the shaft furnace is intended for the production of iron - to allow for the fact that there are variations in the temperature. quantity and quality of top gas supplied to the steam boiler. For example, the mode of operation of a shaft furnace occasionally necessitates short stops. In order to achieve despite this a uniform production of steam from the boiler, it is advantageous, according to the invention, for a combined system of shaft furnace and steam boiler, to provide an additional adjustable heating for the boiler. steam boiler. Because of the ease of adjustment, it is advantageous to use gas, oil or pulverized coal as additional fuel.

   However, obtaining uniform vapor production can also

 <Desc / Clms Page number 17>

 be achieved by the use of a steam accumulator.



   An important additional technical advantage of the combined shaft furnace and steam boiler system according to the invention results from the particular pre-heating of the wind intended for the shaft furnace. In the known shaft furnaces, which work with prior heating of the wind, in particular in such furnaces which require prior heating of the wind above approximately 500 ° C., it is necessary to admit into the heater prior wind = for example Cowper or recuperators - top gas purified to a large extent for combustion It is a great advantage of the combined system according to the invention that the prior heating of the wind takes place with unclean top gas,

   so that a significant saving in installation costs is achieved. By the fact that all of the bitumen contained in the top gas is burnt as permanent gases in the combustion chamber located above the tank, the deposit of soot in the tubular system of the pre-air preheater is practically excluded.

   In many cases it is advantageous to raise the temperature in the combustion chamber to such a point that the mineral dust contained in the top gas is completely melted, because in this case most of this dust is separated over a granulation screen. If in such cases the steam production of the system is kept to a minimum, it is advantageous to use at least the tube bundle of the granulation screen for the steam production, because, in the case of the admission of air on this tube bundle and the use of this one for the preliminary heating of the air, the temperatures of the tubes would rise too strongly. But there is also the possibility to completely suppress the production of steam in the system according to the invention when the tube bundles are used,

   which must withstand a high load, tube bundles to which the lining of the combustion chamber may also belong, for heating air which is at a significantly higher pressure level, for example above 20 atm , because in this case the heat transmission is significantly increased. Such combinations are generally only possible in combination with hot air turbines.

   This procedure can also be carried out by burning, in the combustion chamber placed above the shaft furnace, for the top gas, only the part which is necessary for the preliminary heating of the wind, while the other part gas, which is generally larger, is subjected to normal gas scrubbing operation and is used as a scrubber.



   The essential feature of the eighth exemplary embodiment of the combined shaft furnace and steam boiler system according to the present invention consists in that at least two shaft furnaces are connected to a steam boiler in such a way that they supply gas. to this one.



  When operating the shaft furnace with liquid casting, and in particular when the shaft furnace is simultaneously intended for the production of iron, such a combined system involves significant difficulties owing to the relatively uneven production of iron. gas from the shaft furnace, - whereas one of the most important conditions for the operation of a boiler is the supply and combustion of the fuel as uniform as possible and as precisely adjustable as possible. Liquid casting shaft furnaces, in particular shaft furnaces which are used to obtain iron, has certain irregularities.

   These are based, in particular, on the variable and difficult to regulate permeability of the melting zone of the furnace with respect to the gas, and also on the phenomena of separation of the mixture from the melting bed composed of several constituents, and in particular on the discontinuity which is caused in the operation of the furnace by the periodic casting.



   The present invention provides a solution to the problem of adapting the production of gas by the gas to each other as far as possible.

 <Desc / Clms Page number 18>

 shaft furnace and the gas requirement of the boiler. The measurements according to the invention relate to the dimension of the shaft furnace. They start from the observation that, in the case of the addition of the effects of several organs, of the same type by themselves, the individual effects of which are subject to notable but irregular variations, the sum of the effects presents variations. weaker.

   The application of this observation to the present case consists in that, instead of a single shaft furnace organically cooperating with a steam boiler, there are two or more shaft furnaces - each of which has one. correspondingly reduced production -, so that two or more furnaces give up their gas to a steam boiler. The action of this measure on the whole system is as follows:
The variation in gas production, expressed in heat output, is for example + ¯ 10%. Heat output consists of sensible heat and chemically bound heat. If we divide the large shaft furnace into two furnaces, each having half its production capacity, each of them must provide 50% of the total gas production.

   Its own gap in gas production is still 10% of this 50%, i.e. 5% of the total amount of gas. As these irregular variations are to a great extent compensated for by combining the gases from several furnaces, it is therefore possible, in the case of the distribution of the total gas production to two shaft furnaces, to count with a variation which is not more than approximately 2-3%.



   The distribution according to the invention of the total output of the shaft furnaces has yet another important advantage, which is based on the fact that steam boilers in most cases require that it be possible to regulate significantly and quickly their production. If the steam boiler is combined with a single shaft furnace, this adjustment of the output of the boiler causes a large variation in the operation of the shaft furnace, which is felt in the nature and quantity of its products. Proper operation of a shaft furnace combined with a single steam boiler, subject to the regulation, is therefore not possible or at least is made difficult.



   According to the invention, in the event that two or more shaft furnaces are to supply a boiler with the gas which they produce, one of the furnaces is operated as a control furnace, while 'the other or the other furnaces are operated as regularly as possible and only or predominantly from metallurgical points of view. At least one of the shaft furnaces, working in the combination according to the invention , can then permanently deliver high value and uniform products, with a very large simultaneous decrease in the variation of gas production for the steam boiler.



   The ninth exemplary embodiment of the invention consists of a combined shaft furnace and steam boiler system, which includes cooling of the shaft furnace, in which the shaft furnace is provided with individual circulating cooling elements. water, with which the amount of water escaping in the event of a leak is automatically limited.



   In a combined shaft furnace and steam boiler system provided with such a shaft furnace cooling device, it is particularly advantageous to use the cooling of the shaft furnace for preheating the tank. feed water to the steam boiler.



   There are already known devices for cooling shaft furnaces, in which, for example, the furnace is, in its hot part, surrounded by a jacket with water circulation, in which hot water is produced or steam. However, the use of these known devices for cooling shaft furnaces has not developed, especially in the case of shaft furnaces which are used to obtain iron, because this jacket has to circulate.

 <Desc / Clms Page number 19>

 In the presence of liquid iron, water represents a serious source of danger. The possibility, increased precisely in such a mode of operation, of a leakage of the water circulation jacket would have the consequence is the penetration of water into the oven chamber,

   A possibility which is difficult to control and the consequences of which cannot be foreseen and which, in certain circumstances, could cause explosions in the furnace chamber.



   The present invention avoids these drawbacks and proposes to use the heat of the cooling water also in the case of shaft furnaces which produce iron in the liquid state or in which there are conditions which prevent up to here the use of heat from the cooling water maintaining operational safety. This problem is solved, in accordance with the invention, by the fact that the water circulation jacket is replaced by a fairly large number of cooling elements, each of which is constructed as a small steam generator and has an inlet. adjustable condensate water.

   The desired operating safety is obtained in particular by the fact that devices are provided which, when a leak occurs in such a cooling element, ensure the fastest closing of this element with respect to the inlet. water or its automatic shutdown.



   Two different methods of cooling the shaft furnace are described below:
The first mode of cooling the shaft furnace consists in applying the principle of the Schmidt boiler to the present cooling problem. The Schmidt boiler has, as is known, a closed internal circuit of water of the boiler, which transfers its heat, outside the boiler or outside the heating gas region, in special temperature exchangers, to an external water or water vapor circuit, in which a Steam turbine, for example, is interposed According to the invention, each cooling element of the shaft furnace is constructed like a Schmidt boiler, that is to say it is traversed by a circuit of closed water, which gives up its heat,

   in a suitable place, away from the oven, in a particular temperature exchanger, in a second water or steam circuit, in which the heat is used This second circuit is advantageously common to all the cooling elements o With In this mode of cooling, the quantity of water which can penetrate the furnace as far as possible from a point where a leak occurs is limited to the small quantity which is contained in the first closed circuit of the cooling element considered. Furthermore, in the event of a leak, even a small one, the pressure in the first closed circuit of the cooling element drops rapidly, so that the fault can be immediately detected and that appropriate countermeasures can be taken. taken.



   The advantage of the described cooling method of the shaft furnace consists, in addition to the use of the significant heat losses due to water cooling, in the saving of cooling water. As is known, notably in the mode of cooling employed heretofore, in particular of blast furnaces, the supply of the large quantities of cooling water required in many places of the furnace constitutes a problem. difficult.



   The technical realization of the cooling of the shaft furnace according to the invention takes place on the basis of the elimination as complete as possible of any risk in consideration of the rather harsh metallurgical treatment. The constructional characteristics of another method of cooling the shaft furnace are as follows:
Circulating water cooling tubes with

 <Desc / Clms Page number 20>

 a clearly directed uniform flow. Box-shaped bodies have heretofore been used for the water cooling of shaft furnaces, in which an irregular and completely uneven flow occurs. Such bodies are, for example, the water circulation jackets of generators and shaft furnaces, cast blowing nozzles, blowing nozzle chambers, etc. of shaft furnaces and the like.

   As an example of the improved construction according to the invention, there is shown schematically in Fig. 3 the construction of a blowing nozzle. 101 denotes the cooling tube with the water inlet 102 and the water outlet 103. In a manner known per se, the cooling tube is helically wound on itself in such a way that 'it comes back on itself and the inlet and outlet of the water are located on the same side. 104 designates the nozzle body to be protected by the cooling tube 101 and which can be constructed in several parts.

   Instead of a tube wound helically around the nozzle, it is also possible, to shorten the water path, to use several tubes wound in a helix, with separate water inlet and outlet. are then arranged one after the other in the direction of the nozzle, or else the different propellers are wound one inside the other. The cooling tubes consist, depending on the heat transfer required in each case, of electrolytic copper, bronze, steel, etc.



   The wall of the furnace itself is, according to the invention, also cooled by tubes, which extend essentially in the vertical direction or essentially in the horizontal direction; these two types of tubes can also be used on the same furnace. Vertical tubes generally have the advantage that they allow a natural circulation of water, whereas tubes extending in a horizontal direction must have recourse to forced circulation. Despite this disadvantage, it is, in accordance with this practice, used to the invention, advantageously horizontal tubes in the lower part of the shaft furnace, in which the liquid products, such as slag and iron, in certain circumstances exert a strong pressure from the inside on the wall from the oven.

   The annular tubes, which in such a construction are arranged one above the other and envelop from the outside, for example the work of the furnace, can withstand noticeable forces in the radial direction and make the fort superfluous shielding hitherto necessary in this place. On the contrary, it suffices to wrap the tubes, from the outside, with a relatively thin iron jacket, which ensures the gas-tightness of the oven.



   In order to make the cooling losses as low as possible, the spacing between the individual cooling tubes is made as large as possible. In the case of tubes with an oval cross section, the tubes are arranged so that the major axis of the cross section is located in the side surface of the furnace.

   It is also possible to obtain an additional spacing of the tubes, with as uniform cooling as possible of the furnace, by the fact that the tubes are provided with ribs or metal points, which more or less fill the space between two adjacent tubes. regions of the furnace wall in which the presence of slag or liquid metal is to be expected, according to the invention, a coating of the tubes or a coating of the gaps between the tubes with ceramic materials is provided, which resist to a great extent the attack of liquid products.



   As such ceramic materials it is suitable to use, for example, silicon carbide, a mass of rammed carbon, or refractory clay, or chromium ore, among others. The cooling tubes are advantageously arranged for reduce heat generation, in an insulating material, for example diatomaceous earth.

   Fig. 4 shows schematically in section, part of the crucible of a shaft furnace with a cooling system according to the invention; fig; 5 schematically shows a cross section of a furnace crucible with the corresponding cooling system. 105 designates the refractory masonry of the

 <Desc / Clms Page number 21>

 oven (figs 4 and 5). 106 denotes cooling tubes, of oval cross section, with attached metal tips 107. 108 denotes the rammed mass of chromium ore, which surrounds the tubes on all sides.
106 and their points 107.

   109 designates the metal casing of the oven, gas-tight 110 (fig. 5) designates the primary circuit, closed on itself, of the water for a cooling element o 111 designates the temperature exchanger for the transmission of heat from the primary circuit 110 to the secondary circuit or working circuit 112, common to all the cooling elements with a steam turbine 113. 114 designates the indicator or other member, which comes into action in the case a decrease in pressure in the primary circuit 1100
In the tenth exemplary embodiment of the invention, it is a combined system of a shaft furnace and a hearth, in which the hearth (for example a steam boiler) comprises a device for supplying air. secondary.

   The particular characteristics of this exemplary embodiment and the technical advantages that can be achieved with it result from the following explanations:
If, in accordance with the present invention, the top gas, obtained in a shaft furnace, is used for heating steam boilers or other industrial furnaces, such gas heaters generally work with an efficiency of as much. better than the initial temperature of the gas to be burnt is higher.

   This fact constitutes an additional essential basis of the present invention, which is characterized by the following points: The height of the layer in the shaft furnace, operating mainly with preheated wind, is only such that there is a complete reaction of the blown oxygen with the charcoal of the feed, mainly forming carbon monoxide, and in the case of the presence of iron ore in the smelting bed, the indirect reduction. This means that, of the parts normally existing in a shaft furnace - work, grate and vessel there is, in the shaft oven according to the invention, only the work and the grate, the latter in certain circumstances in a form. shortened.

   The result of this measurement is that the top gas exiting the charge is very hot, several hundred degrees higher in temperature than the top gas in a shaft furnace of normal construction and operation.



  The top gas is made to arrive, with this high outlet temperature, through a suitably insulated pipe, to the heating device placed in the immediate vicinity of the shaft furnace; in most cases this is a device for heating a steam boiler, as a steam boiler can be easily mounted in the immediate vicinity of the tank furnace. The top gas is normally burned in the device. heating with secondary air. In particular in the case of boilers, these can also be basically operated as flue-gas-heated boilers, the cooled top gas being collected for later use.



   It should be noted, as a particular advantage, that a shaft furnace operating in accordance with the invention can work with bituminous coal, without the known difficulties caused by the tarry constituents contained in the top gas present. . In the shaft furnace operating in accordance with the invention, the bituminous constituents undergo cracking due to the high temperatures of the top gas and cannot separate as tar or pitch drenching the pipe system. On the contrary, the gas is carburized. effectively by the tarry constituents which have undergone cracking.



   For various applications of hot top gas as a heating gas, it is advantageous to dust off the latter before combustion. Different devices and measures are available for this dedusting.



  In accordance with the invention, in order to obtain a top gas which is low in pressure

 <Desc / Clms Page number 22>

 However, the shaft furnace is widened above the load, for example in the form of a hopper, thereby reducing the speed of the gas, before it is discharged from the upper part of the furnace.



   CLAIMS.



   1) Combined shaft furnace (e.g. blast furnace, low-pit furnace, casting generator) and hearth (e.g. steam boiler, flue gas-heated boiler, industrial furnace, gas burner), characterized in that a shaft furnace (eg blast furnace, low-chamber furnace, casting generator) connected directly to this hearth and at the same time serving for production is used as the heating installation for the hearth of metal (eg iron).



   2) Combined system of casting generator and furnace, characterized in that the casting generator has at least one wall in common with the combustion chamber of the fopere
3) Combined casting generator and hearth system according to Claim 1 or 2, characterized in that the casting generator is constructed to have a thin layer of coal, so that the gas produced passes through high temperature in the combustion chamber of the fireplace (eg steam boiler).



   4) Combined system of casting generator and steam boiler according to one of the preceding claims, characterized in that, between the gasification device and the combustion chamber is formed an opening in the form of a nozzle, which maintains a higher pressure in the gasifier and which ensures good mixing with the combustion air when the heating gases flow into the combustion chamber of the boiler.



   5) Combined system of casting generator and steam boiler according to one of the preceding claims, characterized in that, in front of the gasification chamber of the casting generator is arranged a - pre-heating and distillation chamber slow for coal, which is traversed by part of the gas produced in the gasification apparatus, as purging gas.



   6) Combined system of casting generator and boiler va- can according to one of the preceding claims, characterized in that the passage of coal from the pre-heating chamber and slow distillation in the gasification chamber is controlled by a special regulator, which regulates the height of the carbon layer in the gasification chamber.



   7) A method for using the combined system according to Claims 2-5, characterized in that an ore (eg iron ore) is added to the gasification coal.


    

Claims (1)

8) A method according to Claim 7, characterized in that, in the case of sticky carbon, the latter is spread periodically in a thin layer, in the cold state or in the preheated state until the beginning of agglutination, on the hot surface of the coal in the gasification chamber. 9) Method according to Claim 7, characterized in that iron ore is fed directly to the furnace structure, for example by blowing in ore dust with the gasification air. <Desc / Clms Page number 23> 10) A method according to each of Claims 7 to 9, characterized in that the combustion air is enriched with oxygen. 11) Process according to Claim 10, characterized in that more highly concentrated oxygen is blown into the structure, below the plane of the main nozzles, supplied with air 12) Method according to each of Claims 7 to 11, characterized in that the liquid slag is cooled in the combustion chamber of the boiler. 13) A method according to each of Claims 7 to 12, characterized in that the liquid slag is cooled, with prior heating of the combustion air. 14) Method according to each of claims 7 to 13, characterized in that one adds to the gasification coal additive materials, such as sand, lime, bauxite, etc ..., to obtain specific products based slag, such as slag bricks, slag wool, cement, etc. 15) Combined system according to Claim 3, characterized in that the casting generator is located so close to the boiler that the gas is led at its maximum temperature into the boiler, and the devices for the admission of wind to the generator and for loading fuel and additives into it are located on the generator side remote from the boiler. 16) A combined system according to Claim 15, characterized in that the wall of the generator, constituting a wall of the boiler, is curved or circular in shape with its convex side facing outward. 17) Combined system according to Claim 15, characterized in that the generator surrounds the boiler on several sides and in particular has a U-shaped cross section. 18) Combined system according to Claim 15, characterized in that the generator surrounds the boiler on all sides, and in particular has a circular cross section. 19) Combined system according to Claim 15, characterized in that the generator, mainly of circular cross section, constitutes the lower part of the boiler, and widens upwards in the form of a hopper, and the secondary air is blown directly into the space above the generator. 20) Method for using the combined system according to claim 15 to 19, characterized in that a controlled vortex movement, for example circular in shape, is produced by the secondary air in the space above the generator. 21) Method for using the combined system according to claim 15 to 19, characterized in that the pressure in the generator and in the combustion chamber of the boiler is increased above the normal pressure., And behind the pressure. The boiler is fitted with a turbine driven by the burnt gases, for the expansion of the burnt gases. 22) Combined shaft furnace and steam boiler system according to Claim 1, characterized in that the solids contained in the gas are brought to a completely liquid state by melting in the steam boiler and are separated from the gas of smoke in this liquid form. <Desc / Clms Page number 24> 23) Combined system according to Claim 15, characterized in that a melting chamber boiler is used for this purpose. 24) Combined system according to Claim 15, characterized in that the combustion air for the melting chamber is heated to a temperature higher than the usual temperature, for example to more than 450 C 25) Combined system according to Claim 15, characterized in that both the preliminary heating of the wind for the shaft furnace and the preliminary heating of the combustion air for the boiler take place with the aid of flue gases of the boiler. 26) Combined system according to Claim 15 to 18, characterized in that the combustion chamber or the melting chamber of the boiler comprises additional heating, for example with pulverized coal or with oil. 27) Combined system according to Claim 15 to 19, characterized in that the smelting bed of the shaft furnace is enriched in fine ore. 28) Combined system according to claim 15 to 20, characterized in that the fine ore or ore dust is brought directly to the melting chamber of the boiler, and is brought into the boiler in the state of complete melting. 29) Combined system according to Claim 15 to 21, characterized in that the fine ore or the ore dust is added fluxes, for example CaO or SiO2. 30) Combined system according to Claim 15 to 22, characterized in that the lime necessary for the operation in the shaft furnace is introduced entirely or partially in the form of limestone dust in the melting chamber of the boiler. 31) Combined system according to Claim 15 to 23, characterized in that the slag, obtained in the liquid or pasty state in the boiler, is granulated by means of water and the granulated product is brought to the smelting bed of the furnace tank. 32) Combined system according to Claim 15 to 24, characterized in that the liquid or pasty slag obtained in the boiler is cooled in the form of plates or pieces and is added, after appropriate division, to the melting bed of the shaft furnace . 33) A combined system according to Claim 15, characterized in that the steam boiler comprises, in addition to the device for the combustion of the top gas of the shaft furnace, a device for the combustion of a secondary fuel, for example pulverized coal. 34) Method carried out with the combined system according to Claim 1, characterized in that, in the combustion chamber of the boiler, in addition to the top gas from the shaft furnace, gaseous, liquid or solid substances which, with preheated air, give, by combustion, a temperature higher than that necessary for the fusion of the solid constituents contained in the top gas. 35) Method according to Claim 26, characterized in that the low-shaft furnace is operated as much as possible under the bleak load and the adjustment of the heat input into the boiler is carried out by the metering of the secondary fuel, for example pulverized coal and its combustion air. <Desc / Clms Page number 25> 36) A method carried out with the combined system according to Claim 1, characterized in that, in the case of a liquid casting shaft furnace, the production of iron is significantly reduced in the case of its operation as a blast furnace or furnace. low tank, and the production of iron is increased in the case of its operation as a casting generator. 37) Method according to Claim 29, characterized in that the metallurgical treatment of iron ores with solid fuels in a shaft furnace is reduced in such a way that the top gas is burnt directly, in the hot state and substantially not uncluttered, in a boiler assembled in the tank oven. 38) A method according to claim 29, characterized in that one employs, for the metallurgical treatment, ores poor in iron and coal or fuels rich in ash, and the hearth used for the combustion of the top gas consists of a boiler with fusion chamber 39) Method according to Claim 29, characterized in that the shaft furnace is operated with a load height of approximately 1.5 to 2.5 m, preferably approximately 2 m. 40) Process according to Claim 29, characterized in that the quantity of iron ores to be reduced is determined in such a way that the quantity of iron obtained per unit of fuel is such that the top gases formed during the reduction, reach with sufficient temperature in the hearth, for example the melting chamber boiler. 41) Installation for carrying out the process according to Claim 29, characterized in that a melting chamber boiler is used as the hearth. 42) A method according to claim 29, characterized in that in the case of the use of a combined system of casting generator and steam boiler, additionally charged into the casting generator such a quantity of iron ore that the quantity of iron obtained be appreciably increased in relation to the quantity of iron normally produced in the casting generator and that the quality of the gas is still sufficient to allow direct combustion of the hot unclean gas in the steam boiler (preferably the melting chamber boiler) with a sufficiently high temperature 43) Method for using the combined system according to Claim 1 to 6 or 15 to 27, for the metallurgical treatment of poor iron ores with gangue rich in silica, characterized in that, by applying the highly acidic smelting process, ash-rich coal is used as fuel. 44) A method according to claim 38, characterized in that the top gas from the shaft furnace, which is available in particularly large quantities due to the operating mode, is burned in a hearth, for example a steam boiler. 45) Process according to Claim 39, characterized in that a melting chamber boiler is used as the steam boiler, the combustion chamber of which is arranged above the shaft furnace. 46) Combined system according to Claim 1, 3 to 6, 15 to 34, characterized in that at least the combustion chamber of the steam boiler is arranged above the shaft furnace in the vicinity of the opening (s) outlet of the gas from this oven, for example directly above the shaft furnace, and is connected to the gas collecting chamber of the shaft furnace by at least one gas supply (for example one or more tubes or openings of gas supply). <Desc / Clms Page number 26> 47) Combined system according to Claim 46, characterized in that the whole of the steam boiler is arranged, for example as a single-flue boiler, above the tank furnace. 48) Combined system according to Claim 46, characterized in that the combustion chamber alone is arranged in the immediate vicinity of the gas collecting chamber of the shaft furnace, for example above the shaft furnace, while the remaining parts of the steam boiler are arranged in a downward flue next to the shaft furnace. 49) A combined system according to each of Claims 46 to 48, characterized in that a device, using the heat of the flue gases from the steam boiler, serves for the preheating of the blast intended for the shaft furnace. 50) Combined system according to each of Claims 46 to 49, characterized in that a device, using the heat of the flue gases from the steam boiler, serves for the preheating of the combustion air for the combustion chamber of the steam boiler. 51) A combined system according to each of claims 46 to 50, characterized in that on the shaft furnace are arranged cooling elements, which are incorporated in the heat utilization system of the steam boiler. 52) Combined system according to each of Claims 46 to 50, characterized in that the production of steam takes place only in a few tube bundles, subjected to a high load (for example granulation tubes), and / or in the tubes lining of the combustion chamber. 53) A combined system according to each of Claims 46 to 50, characterized in that the combustion chamber serves, using a large excess of air, only for the combustion of the top gas without the production of soot, and the prior wind heating takes place, without the interposition of a steam boiler, directly by heating the tubes by means of hot combustion gases. 54) Combined system according to Claim 1, 3 to 6.15 to 34 or 46 to 53, characterized in that at least two shaft furnaces are joined to a steam boiler in such a way that they give up their gas to this one. 55) Combined system according to Claim 54, characterized in that one of the shaft furnaces is constructed as a control furnace and operates in such a way that it produces to a great extent the control of the quantity of gas required for the heating. steam boiler. 56) Combined system according to Claim 55, characterized in that one of the shaft furnaces works irregularly from the point of view of gas production, while the other or the other shaft furnaces also work. regular as possible, in the event that the boiler steam output is adjusted. 57) Combined system according to Claim 1, 3 to 6, 15 to 36 or 46 to 56, characterized in that it comprises a cooling of the shaft furnace, in which the furnace is provided with individual cooling elements with circu- lation of water, in which the quantity of water leaving in the event of a leak is automatically limited. 58) A combined system according to Claim 57, characterized in that, in the supply pipe from the supply pipe com- <Desc / Clms Page number 27> Along with the individual cooling elements is interposed a shutter member, the closure of which is produced by an indicator instrument, which is controlled by the flow of water or by the pressure in the supply pipe or by the primary circuit. 59) Combined system according to Claim 57 or 58, characterized in that each cooling element, or a group of cooling elements corresponds to a closed water circuit, which transfers its heat outside the boiler, for example to a secondary water circuit. 60) Combined system according to Claim 57, 58 or 59, characterized in that this secondary circuit ensures the preliminary heating of the feed water of a boiler, for example of a boiler working in combination with the tank furnace 61) A combined system according to Claim 57, 58,59, or 60, characterized in that tubes are used as elements for the circulation of water in the region of the furnace to be cooled. 62) A combined system according to Claim 57, 58, 59, 60 or 61, characterized in that for this cooling, substantially horizontal annular tubes are used, arranged in the direction of the periphery of the furnace. 63) Combined system according to Claim 57, 58, 59, 60, 61, 62, characterized in that these tubes are coated in a mass, which serves for protection against liquid products and / or for thermal insulation. 64) Combined system according to Claim 57, 58, 59, 60, 61, 62, 63, characterized in that tubes of oval cross section are employed, on which ribs or extensions are provided in certain circumstances, in particular in the direction of neighboring tubes. 65) Combined system according to Claim 1, 3 to 6, 15 to 36, or 46 to 64, characterized in that the hearth (steam boiler), boiler heated by flue gases, industrial oven, gas burner) comprises a device for the secondary air supply.