Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B1/00—Shaft or like vertical or substantially vertical furnaces
  • F27B1/10—Details, accessories or equipment specially adapted for furnaces of these types
  • F27B1/20—Arrangements of devices for charging
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B5/00—Making pig-iron in the blast furnace
  • C21B5/02—Making special pig-iron, e.g. by applying additives, e.g. oxides of other metals
  • C21B5/023—Injection of the additives into the melting part
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B1/00—Shaft or like vertical or substantially vertical furnaces
  • F27B1/10—Details, accessories or equipment specially adapted for furnaces of these types
  • F27B1/16—Arrangements of tuyeres

Definitions

• the invention relates to a method for operating a shaft furnace, in particular a cupola furnace, to which metallic feedstocks, alloying elements and energy sources, such as coke, are added in the upper part of the shaft and an oxidation medium, such as air, is added in the lower part of the shaft, additives, namely alloying elements, metal chips or dusts are fed.
• dusts in the nozzle level for the cupola furnace furnace wind have been blown in the foundry and in the cupola furnace operation (EP 0 504 700 A1.
• Such dust are, for example, filter dust from cupola furnace dedusting, foundry sands no longer to be processed, dust from the blow room and grinding shop, etc.
• These dusts contain, among other things, Si0 2 , which can be used as a slag generator for the cupola furnace melting process, but also combustible organic components, the calorific value of which can be used for the melting process.
• the calorific value of the combustible constituents of the dusts is used as melting energy and the Si0 2 as a slag generator.
• Problematic constituents of the dusts such as heavy metals, are integrated into the slag in an environmentally-friendly manner, for example glazed. All of these additives introduced into the melting zone of the cupola furnace must be blown in under different and sometimes opposing conditions. While a reducing atmosphere at the injection point is required for the alloy elements, oxidizing must be carried out for dusts with high calorific value. In the case of low-calorific value dusts, it makes sense to include an energy source so that the slagging of the SiO 2 portion of these dusts does not come at the expense of the coke set.
• the invention has for its object to provide a method and an apparatus with which the different requirements described when using the additives mentioned are satisfied, an undesired lowering of the melting temperature is avoided and the formation of pollutants, in particular NO x , can be prevented to an unacceptable extent.
• a method according to claim 1 and a device according to claim 5 serve to achieve this object.
• Advantageous refinements of the invention are specified in the subclaims.
• the introduction conditions of the additives, the fuel and the additionally introduced oxygen can be designed, in particular the speeds set so high, that no flame forms. This allows the emergence Avoid environmentally harmful NO x compounds and the burning of valuable components such as alloying elements.
• the method according to the invention is suitable for all common types of cupolas, e.g. Furnaces operated with hot wind, warm wind, cold wind, secondary wind, fed and unlined furnace types, long-term furnaces, interchangeable furnaces, shuttle furnaces etc. are equally suitable.
• the feedstock of such ovens can include
• wind As known, air (“wind”), which is either preheated (hot wind, warm wind) or has ambient temperature (cold wind), is fed to the furnace as an oxidizing medium via one or more rows of nozzles. This air can be enriched with oxygen.
• the method according to the invention is suitable for all furnace sizes.
• one or more of the claimed combination lances for introducing the additives are installed in the melting plane of the cupola furnace.
• the first substance can be an alloying element, such as a
• Carburizing agent FeSi, SiC or the like
• dust e.g. cupola furnace dust, Used sand, cleaning dust, etc.
• iron shavings a mixture of the aforementioned substances.
• the second substance is used to set the oxidative or reductive conditions that are necessary for the respective use of the first substance. It can consequently be both gaseous, liquid, solid, calorific value-containing substances, predominantly carbon-containing or hydrocarbon-containing substances.
• the third substance compensates for the lowering of the melting temperature caused by the use of the first two substances. It is therefore oxygen that escapes from the facility predominantly at supersonic speed.
• the three material flows can be regulated separately from each other in the range of 0% - 100%.
• the optimal setting depends on the type, amount and composition of substance 1 as well as the respective requirements of the melting shop.
• the introduction conditions via the or each combination lance are designed in such a way, in particular the introduction speeds are chosen so that, under all possible operating parameters, the occurrence of a flame directly in front of the lance is prevented. It is advantageous to introduce the combination lance of oxygen in the second jet at supersonic speed, preferably in the range from 1.5 to 2.5 Mach, and of the additives and fuels in the first jet at maximum speed of sound. This guarantees optimal effectiveness of the process and prevents an increase in NOx values.
• oxygen can be fed to the cupola furnace via separate oxygen lances, predominantly at supersonic speeds.
• the combination lances according to the invention and the oxygen injection lances for the additional introduction of oxygen are preferably introduced into the existing wind nozzles (water-cooled copper nozzles or uncooled stamped nozzles) built-in. However, it is also possible to install these devices and the additional oxygen injection lances in separate feeders in the melting plane of the cupola furnace.
• the iron analysis can be controlled by the use of cast or steel chips and the iron temperature can be reduced if necessary.
• Fig. 1 shows a vertical section through a cupola furnace
• FIG. 2 shows an enlarged partial section through the furnace wall at the level of the melting zone through an inlet duct for the wind, into which a device according to the invention is inserted;
• Fig. 3 shows a longitudinal section along the line III-III in Fig. 4 by a
• Fig. 5 shows an enlarged section like Fig. 4 in a modified
• Fig. 6 is a partial section similar to Fig. 2 at the level of the melting zone through an inlet channel for the wind, in one
• Oxygen injection lance is used; 7, 8 and 9 cross sections through the melting zone of the cupola with an arrangement of combination lances according to FIGS. 2 to 5 and oxygen injection lances according to FIG. 6 in three variants.
• Fig. 1 shows a cupola furnace known in principle with a shaft, in the upper part 1 metallic feedstocks, alloying elements and energy carriers, such as coke, and in the lower part 2, an oxidation medium, such as air, - the so-called furnace wind - via a wind ring 3 and from there is introduced into the melting zone 5 via introduction channels 4.
• Combination lances according to the invention designated overall by reference number 6, are inserted into at least two diagonally opposite insertion channels 4.
• the combination lance 6 is provided with lines 9 for oxygen and 10 for fuel, such as combustible gases, and with a central feed line 11 for additives, such as dusts, used foundry sands, alloy elements, metal chips, carbon and the like.
• the reference numerals 9 'and 10' denote individually operable shut-off valves for lines 9 and 10.
• the structure of the combination lance 6 can be seen in detail from FIGS. 3 to 5.
• a protective tube 12 surrounds two lances arranged in parallel, namely a material lance 13 and an oxygen lance 16.
• the material lance 13 comprises an outer tube 14 for supplying fuel, such as fuel gases (methane, natural gas or the like), Via the line 9 and an inner tube 15 separated from it via an annular gap 14 'for transporting the fuel for supplying additives, such as dusts via the line 11.
• the oxygen lance 16 runs parallel to the substance lance 13, and preferably at a distance X from the latter Outer tube 14 and a distance Y from the inner tube 15, as shown in Fig. 5.
• the distance X is preferably in a range equal to the inner diameter of the oxygen lance 16 and ten times this inner diameter, while the distance Y is preferably in a range between twice and twenty times the inner diameter of the oxygen lance 16.
• the oxygen lance 16 is covered by the fabric lance 13.
• the feed line 10 leads into this oxygen lance 16.
• the oxygen lance 16 In its mouth, the oxygen lance 16 has a Laval nozzle 18, as indicated in FIG. 5 and shown in FIG. 6 for a separate oxygen injection lance 20 in axial section. Because of this Laval nozzle, the oxygen is blown into the melting zone 5 at supersonic speed via the oxygen lance 16 and also via the oxygen injection lance 20 according to FIG. 6.
• oxygen or the fuel gas supplied here is also blown into the fabric lance 13 via the annular gap 14 ′ at the maximum at the speed of sound. Oxygen can also be added to the dust or other additives supplied via the inner tube 15. Here, too, the speed of sound is not exceeded when blowing in.
• FIG. 6 shows, in the same representation as FIG. 2, an oxygen injection lance 20 inserted into another inlet duct 4 for furnace winds with a Laval nozzle 18 inserted into the mouth.
• 6 21 denotes an oxygen line
• 22 a shut-off valve
• 23 a quick-release coupling
• 24 a lance holder for the oxygen injection lance 20.
• the devices 23 and 24 can of course also be provided on the combination lance 6.
• the operator can briefly, for example daily depending on the batch to be used, the operating conditions, the results of analyzes of the furnace content and the fuels and additives that are currently being injected decide whether and to what extent and where it additionally blows in oxygen and additives.
• the introduction conditions in particular the blowing speeds, are so high that there is no flame in the immediate vicinity of the mouth 25 in the Furnace interior 26 forms. This avoids the burning of valuable components such as alloying elements and the like and also prevents the formation of environmentally harmful NO x compounds to an unacceptable extent.
• combination lances 6 according to FIGS. 2 to 5 are inserted diagonally opposite one another into the introduction channels 4 at points 70, 73, while at points 71, 72; 74, 75 oxygen injection lances 20 according to FIG. 6 are used.
• combination lances 6 are again used diagonally opposite one another at points 90, 93.
• Oxygen injection lances are arranged diagonally opposite one another at points 91, 94, while the Feeding channels for the furnace wind at the locations 92, 95, which are also diagonally opposite, are left empty.
• the operator is given great freedom when driving the cupola furnace, which enables him to quickly adapt to changing analysis results, operating conditions, batches, and the introduction of different additives and fuels, so that always can achieve a quality close to the attainable optimum of the melt with a minimum of environmental pollution.
• the introduction of dust and used sands enables eluate-safe waste disposal.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Vertical, Hearth, Or Arc Furnaces (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Blast Furnaces (AREA)
• Manufacture Of Iron (AREA)
• Flexible Shafts (AREA)
• Passenger Equipment (AREA)
• Heat Treatment Of Articles (AREA)
• Pressure Welding/Diffusion-Bonding (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=7811481

Family Applications (1)

Country Status (9)

Cited By (1)

Families Citing this family (8)

Family Cites Families (12)

• 1996
  • 1996-11-13 DE DE19646802A patent/DE19646802A1/de not_active Ceased
• 1997
  • 1997-10-21 ZA ZA9709426A patent/ZA979426B/xx unknown
  • 1997-10-21 TW TW086115547A patent/TW365644B/zh active
  • 1997-10-25 AU AU71806/98A patent/AU7180698A/en not_active Abandoned
  • 1997-10-25 US US09/308,012 patent/US6187258B1/en not_active Expired - Lifetime
  • 1997-10-25 EP EP97948806A patent/EP0946848B1/fr not_active Expired - Lifetime
  • 1997-10-25 AT AT97948806T patent/ATE211250T1/de active
  • 1997-10-25 ES ES97948806T patent/ES2170421T3/es not_active Expired - Lifetime
  • 1997-10-25 DE DE59705923T patent/DE59705923D1/de not_active Expired - Lifetime
  • 1997-10-25 WO PCT/EP1997/005906 patent/WO1998021536A2/fr not_active Ceased

Non-Patent Citations (1)

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