WO2004106558A1

WO2004106558A1 - Fuel system to be delivered into tuyeres during the production of pig iron in a blast furnace, and method and installation for the production and delivery of the fuel mixture

Info

Publication number: WO2004106558A1
Application number: PCT/EP2004/004479
Authority: WO
Inventors: Holger Wulfert; Walter Hartig; Rongshan Lin; Horst Zewe
Original assignee: Loesche Gmbh
Priority date: 2003-05-26
Filing date: 2004-04-28
Publication date: 2004-12-09
Also published as: EP1629125B1; EP1629125A1; DE10323902B4; TW200508399A; PL1629125T3; ES2377499T3; TWI290957B; DE10323902A1; ATE537273T1

Abstract

The invention relates to a fuel mixture that is to be delivered into tuyeres during the production of pig iron in a blast furnace as well as a method and devices for the production and delivery of the fuel system. In order to optimize the production of pig iron in blast furnaces, an inventive fuel system is provided which is to be blown in according to the PCI method via tuyeres and can be produced in an extraordinarily simple and efficient manner. Said fuel mixture comprises a ready-to-inject coal dust-cinder mixture which is produced by joint grinding, especially in a vertical rolling mill. The invention makes it possible to improve the blast furnace process while allowing extraordinarily efficient utilization of the especially oil-contaminated cinder materials obtained in milling processes.

Description

FUEL MIXTURE FOR SUPPLYING IN BLOW SHAPES IN ROLLING PRODUCTION IN THE HIGH OVEN AND METHOD AND APPARATUS FOR PRODUCING AND SUPPLYING THE FUEL MIX

The invention relates to a fuel system for supplying blow molding in pig iron production in the blast furnace according to the preamble of claim 1, a method for producing and supplying the fuel system according to the preamble of claim 8 and a plant for producing and supplying the fuel system according to the preamble of claim 18 ,

It is known in the production of pig iron in blast furnaces to reduce coke consumption with the hot blast, which is introduced via the wind or blow molds in the lower part of the rest, even more reducing and heating fuels, such as coal dust, oil or natural gas, blowing for coal dust, in particular the PCI (Pulverized Coal Injection) method is used.

In the company brochure "Pulverized Coal Injection Systems" of Paul Wurth S.A. From 05/2002 grinding plants for the production of coal dust as well as distribution and supply systems for the pneumatic supply of the coal dust in blast furnace wind forms are described after the PCI procedure.

WO 99/64636 describes a process in which pulverized coal prepared with a catalyst additive is blown in. As a catalyst supplement, aqueous solutions of compounds of the subgroup elements zirconium, molybdenum, tungsten, manganese, iron, cobalt, nickel, copper, zinc or of aluminum, tin or lead, in particular a copper sulfate solution proposed.

In the article "Blast furnace efficiency enhancer for pulverized coal injection" of the journal "Steel Technology" February 2000, page 61 et seq., The aforementioned method is further described. The coal dust supplied for the partial replacement of coke via the blow molds has a particle size <1 mm and a moisture content <3%, and 350 to 600 ml of catalyst solution are fed per tonne of coal. The feeding takes place with the aid of a separate device, which is arranged after a raw coal silo and in front of an MPS mill, wherein the raw coal is prepared by spraying with the catalyst solution. The disadvantage is that the spray device must meet special requirements because of the corrosive properties of the catalyst solution and also in addition a cleaning system for regular cleaning of the nozzle is required.

From DE 100 50 332 Al a method and an apparatus for preparing fuels, in particular coal dust, for the production of pig iron, in which a catalyst containing cerium and iron salts of organic and / or inorganic acids and a reduction in the ignition temperature and an acceleration of combustion and thus causes a faster burning of the residual coke is used. The preparation of the pulverized coal is carried out with an aqueous solution of the catalyst during the grinding of the raw coal to pulverized coal. The coal mill, eg an air flow roller mill of the LOESCHE Type, must be equipped to prepare the coal dust with appropriate feeders and sprayers. In order to achieve effective wetting of the coal particles, measurement and control facilities are also required, which must be included in the control and safety concept of the entire grinding plant and are associated with additional investment and costs.

The invention has for its object to provide a fuel system for feeding via the blow molding of a blast furnace and a method and a system for producing and supplying the fuel system, which in an extremely efficient production and supply of the fuel system to an improved fire behavior and optimized blast furnace process to lead.

With respect to the fuel system, the object is achieved by the features of claim 1, procedurally the object is solved by the features of claim 8 and according to the device by the features of claim 18.

The invention is based on the idea of using a mixture of at least one carbon carrier and a prereduced iron material as the fuel system and feeding it together with the hot blast and / or oxygen through the wind or blow molds to the blast furnace, for example according to the PCI process.

As carbon carriers, which can also be referred to as reducing agents, solid, liquid and gaseous carbon carriers and their suspensions are generally suitable. As solid carbon carriers, coal, for example hard coal, but also lignite, granulated coal, coal mixtures, coal coke mixtures and plastics, for example as plastic-carbon mixtures or plastic-oil suspensions, as a liquid carbon carrier oil and gaseous carbon carriers such as natural gas used and together with a prereduced iron material in a predetermined grain size in blow molds are fed to the blast furnace.

Preferably, a fuel system is used which contains a solid carbon carrier, e.g. Coal or a mixture of coal and petrol coke, and as a prereduced iron material, a scale material, e.g. Mill scale, contains.

It is particularly advantageous that the mixture according to the invention in a mill, in particular in a roller mill with integrated sifter, for example in an air flow roller mill of the LOESCHE type, a common grinding process, suitably a grinding-drying, subjected and with a predetermined grain size can be supplied to the blow molds.

In principle, the carbon carriers or the fuel raw material and the scale material can be ground separately in a suitable mill or grinding system and fed together in a particularly adjustable mixing ratio or else separately to the blow molding of the blast furnace. However, particularly rational and preferred is a common meal-viewing process, e.g. in an airflow roller mill.

It has been found that a coal dust-scale mixture in which the proportion of scale can be between about 0.5% and 55%, advantageously between 3 and 15%, and which extremely efficient and efficient grinding, leading to a significantly improved combustion behavior in the blast furnace and can also lead to a reduced incidence of unburned coal.

Compared to the normal combustion of the coal and the known PCI process, a significant burnup acceleration of the reducing agent, in particular of the pulverized coal injected and at least partially of the coke, was found. It is also advantageous that due to the admixture of scale in pulverized coal injection, a smaller amount of ore and reducing agent to be fed per ton of pig iron production must be used. It has also been found that a lowering of the flame temperature is achieved by the addition of scale according to the invention to coal dust, which is why the Sauerstoffzugäbe and thereby the surface area performance can be increased.

Furthermore, a significant advantage of the fuel-scale mixture according to the invention is the rational and effective utilization of scale material, in particular the mill scale produced in rolling processes and the like in relatively large quantities. In essence, scale is an iron (II, III) oxide formed on a steel surface during hot forming and heat treatment

(Fe O = FeO. Fe O), which is admixed with

3 4 2 3 conditions of calcium oxide CaO, silicon dioxide SiO, aluminum oxide Al 0, sodium oxide Na 0, magnesium oxide

2 3 2

MgO, manganese and traces of sulfur, P 0,

2 5 comprises TiO, Zn, Zr, Cu, Cr, Co, V, Ni and Pb, and

2 during rolling and forging drops (mill scale or hammer blow) or rinsed from the steel surface, sprayed or removed by descaling or rolling. The iron content in the mill scale can be between 30 and 80%, which is why it makes sense from the point of view of economic efficiency and also from an environmental point of view. So far, a recovery in the form of pelleted or briquetted mill scale, which is given together with the blast furnace coke and Möller over the Gicht- closure a blast furnace. However, a disadvantage is the need for pelleting or briquetting, which requires additional process steps.

According to the inventive method for producing and supplying the fuel system of the invention, a carbon carrier, in particular a solid carbon carrier, or a mixture of two or more carbon carriers and a prereduced iron-containing material are fed to a mill and ground together and with a predetermined grain size according to the PCI method fed via blow molding a blast furnace.

It is advantageous, as a solid carbon carrier or fuel raw material coal, especially hard coal or lignite, or a mixture of coal and petroleum coke and prereduced iron material scale, for example mill scale, which may have a metal or iron content between 30 and 80%, a roller mill Give up with a built-in classifier in a predeterminable mixing ratio and subjected to a grinding-visual process.

It is expedient to use a fuel raw material or mixture with a calorific value> 3000 kcal / kg, a moisture content of about 15% and a feed particle size of <10 to about 80 mm. The mill scale can be conveyed separately from the fuel raw material to the mill task and mixed with the fuel aterial or the fuel particles in the mill. However, it is advantageous for the milling and screening process and the desired ground product to mix a mixing device, for example a mixed bed or a mixing drum, upstream of the coal mill and feed the fuel raw material with the scale material as a feed mixture, and to mix the fine material mixture after the classifier in a filter to separate and as blow-ready fuel system to supply the blow molding of the blast furnace.

From a safety point of view, grinding in an inert atmosphere is advantageous. By using a hot gas, e.g. Flue gas, which is brought in a hot gas generator to the required temperature, the feed mixture is deprived of moisture and carried out a grinding-drying. The grinding can also be carried out in an air-driven grinding plant with hot air as drying gas. Another possibility for supplying hot gases for the grinding-drying process is the use of waste-gas or Cowpergas.

In principle, the mill scale can occur during a mechanical descaling with a hydraulic cleaning process or during rolling and transport processes by abrasion. As a rule, the scale has a high moisture content (up to 90%) and is contaminated with lubricating oils and greases from the rolling processes. After a subsequent treatment, eg in sales tanks or by pressing operations, the water content in the range of 2 to 15%, the oil content between 0 and 5% and the grain size of about 0.5 mm to a maximum of 50 mm. An advantage is a feed mixture of about 85% fuel raw material, such as hard coal, and about 15% mill scale. The raw coal in this mixture may have a particle size of approximately between 0 and 10 mm (warning carbon) or between 0 and 50 mm. The grain size of the scale can be up to a maximum of 50 mm. The grain size after the mill is 50 to 80% <90 microns.

In principle, a common grinding of raw coal or raw coal and petroleum coke and Zundermaterial in all suitable grinding systems and mills, z. In ball mills and vertical roller mills and the like. A feed mixture of coal / Petrolkoks and Zundermaterial does not have a negative effect on the milling process.

Surprisingly, it has been found that the co-grinding of the solid fuel raw material, in particular hard coal, and the scale in a LOESCHE type roller mill can be carried out extremely inexpensively, efficiently and efficiently. In addition, it has been found that the parameters characterizing a milling process, such as the specific working requirement and the power factor of the mill, are not adversely affected by addition of mill scale to hard coal or to a mixture of hard coal and petroleum coke of 5 to 15%. Also, the particle size distribution is almost identical, ie there are in the range of 50% R 90 microns to 0.05% R 90 microns only very small differences, for example, the specific labor requirements between a pure coal grinding and grinding with scale. As the proportion of scale in the fuel mixture increased, even a reduction in the workload of the mill was noted. Particularly advantageous is an improved ignition behavior of the fuel-scale mixture in the blow molds, which can also be due to synergy effects of the common milling of mill scale and a fuel raw material. Thus, it was found that after the common milling process, scale particles adhere to the fuel particles and, despite the density differences between the fuel and scale particles, separation occurs neither during grinding nor during sifting and also during the feeding and injection according to the PCI process. It has surprisingly been found that the intimate connection between the carbon particles and the scale constituents significantly increases the burn-up acceleration.

Both components are brought into intimate contact during the grinding process by the comminution processes under each roller. It is assumed that the metal oxides present in the mill scale will adhere quasi to the carbon grain or the carbon particles. Also of advantage for this are the oil residues present in the scale, which support the bonding or bonding process. This intimate connection between the coal grain to be burned and the scale constituents, which are metal oxides having a defined redox potential and a catalytic action, leads to a surprisingly improved burning behavior of the coal dust particles. The fuel system according to the invention or the ready-to-inject fuel-scale mixture thus not only offers the possibility of recycling the by-product scale in an extraordinarily simple and economical way, but is simultaneously associated with an optimization of the blast furnace process. It is also advantageous that due to the supply of Walzenzunders on the blow molding, the oil of the mill scale is exposed to very high temperatures and the risk of the formation of harmful combustion products is very low. Measures for encapsulation on oil oily adhering oil, which are described for example in DE 100 38 566 AI, are therefore not required.

In terms of the device, it is provided according to the invention that in a system for a PCI process in front of the mill and separate from the devices for the fuel raw material, a conveying device and / or a metering device for the scale material stored in a storage bunker or silo, e.g. Mill scale, are arranged.

Alternatively, for a premix of the mill scale or of the prereduced iron material and of the fuel raw material, a premixing device may be arranged in front of the mill, so that a feed mixture having a predeterminable mixing ratio is formed and subjected to milling, e.g. can be supplied via a metering bunker.

In addition, it may prove useful if, after a filter in which the coal dust-scale mixture is separated from the mill, and in front of a silo for receiving the ready-blowing mixture, a further mixing device is provided.

As a rule, after the Feingutsilo transmitting vessels or feed tank and a distribution silo are arranged, and via injection lines, the supply of the fuel mixture according to the invention takes place in the blow molding of the blast furnace. It is advantageous that the fuel system according to the invention can be fed to the blast furnace in the same way as pulverized coal by the PCI process via the blow molds. Reference is made by way of example to the company brochure "Pulverized Coal Injection Systems" from Paul Wurth SA, in which the conventional feed systems using gravity or pneumatic, as well as distribution and conveying systems, including dense phase or thin-flow conveying, and the measuring and control systems and one possible Preheating of the pulverized coal are described in detail.

The invention will be further explained below with reference to a drawing; in the single drawing a system diagram for explaining the fuel system according to the invention and the process sequence and devices of the system is shown in a highly schematic manner.

The process sequence reveals four major process steps for the manufacture and use of a new blast furnace blast furnace fuel system.

In a first stage, the preparation of the components for the fuel system 10 according to the invention, which is produced by a common grinding in a mill 2 takes place. In the present example, an air flow roller mill of the LOESCHE type is provided for the grinding process. However, other vertical Wälzmühlen or ball mills and the like can be used.

Starting materials are at least one solid carbon carrier 6, for example coal, in particular hard coal or lignite, or a mixture of hard coal and petroleum coke, hereinafter referred to as raw coal 6. The raw coal 6 passes from a heap 8 in a raw coal bunker 16 and a conveyor or coal allocation 15 to a conveyor 5, which is the mill 2 upstream. As a second component, a prereduced iron material 7, preferably scale material, such as mill scale, from a scale bunker 17 or a storage device with the aid of a conveyor or scale allocation 14 of the conveyor 5 for producing a feed mixture 4 is fed.

Alternatively, the feed mixture 4 can also be produced in a mixed bed or a mixing drum by mixing the raw coal and the scale material with one another and feeding it to the mill via a metering bunker (not shown). It is expedient to feed the feed mixture 4 from raw coal 6 and mill scale 7 in a predeterminable mixing ratio of the mill 2.

In a second process step, the grinding of the feed mixture 4 to a ready-blowing fuel system 10. This takes place in the present embodiment in an air flow roller mill 2 and in inert mode. By supplying a heated in a hot gas generator 11 to the required drying temperature inert or hot gas 9, the feed mixture 4 is subjected to a grinding-drying. The hot gas 9 may advantageously be circulated (not shown) and the hot gas generator 11 may be e.g. be operated with blast furnace gas.

It is of particular advantage that the milling of the fuel scale feed mixture 4 in the mill 2 can be carried out in the same way as the grinding of raw coal to pulverized coal. The abandoned mill scale 7 has usually undergone a pretreatment to reduce the water content and the adhering oil. By the grinding-drying of the feed mixture 4 in the mill 2 with integrated classifier 3, a fuel system which optimizes the blast furnace process is produced with the ready-to-inject fuel-scale mixture 10.

In a downstream filter 12, such as a fabric or bag filter, the dust-like fuel-scale mixture 10 is deposited and passes through a cellular wheel 18 in a silo container 20th

The silo container 20 symbolizes the third method step with the further devices for pneumatic feeding of the ready-to-inject fuel-scale mixture 10. This includes the silo storage, the regulation of the pneumatic feed of the ready-blowing fuel-scale mixture 10 by means of a nitrogen pressure vessel 21, transmitting vessels or feed containers 22, 23 and a distribution container 24 and a connecting line or feed line 25. From the distribution container 24 go accordingly the number of blow mold 27 injection lines 26 for the blow mold 27 from, over which the einblasfertigige fuel or raw coal-scale mixture 10 is blown together with the hot blast. O Due to the high temperatures of about> 2000 C in the blast furnace blast furnace, the carbon of the fuel burns to carbon monoxide, which reduces the iron oxide of the ores to iron to form carbon dioxide. Since the scale particles of the fuel scale are mainly iron oxides, they are also reduced.

An essential advantage of the fuel system according to the invention, consisting of an injection-ready fuel-scale mixture, is that the reduction average amount for the scale compared to a comparable amount of ore to be fed, based on the metal content, is lower. At the same time a recovery of a by-product is achieved. It is also advantageous that, in particular oil-contaminated Zundermaterial can be used. It has also been shown that the feeding of the fuel-scale mixture according to the invention via the blow molding of the blast furnace to optimize the blast furnace process, eg by increasing the Abbrandbeschleunigung of the reducing agent, primarily the injected coal and at least partially also of the coke leads. Further advantages are the rational, effective production and supply of the fuel system according to the invention.

Claims

Fuel system for feeding in blow molding in the production of pig iron in the blast furnace, with at least one carbon carrier, which is fed to the blast furnace together with hot air and / or oxygen according to the PCI method, characterized in that a prereduced iron material (7) to the carbon carrier (6) admixed is.

Fuel system according to claim 1, characterized in that as the carbon carrier (6) a solid, liquid and / or gaseous fuel and as a prereduced iron material (7) a Zundermaterial is included and that it as a einblasfertiges fuel-scale mixture (10) on the Blow molds (27) the blast furnace (28) can be fed.

Fuel system according to claim 2, characterized in that in the fuel-scale mixture (10) as a solid carbon carrier (6) coal, a coal mixture, coke or coal-coke mixture and / or plastic material, liquid carbon carrier oil and gaseous Carbon carrier a gas, such as natural gas, is included. Fuel system according to claim 2 or 3, characterized in that the fuel-scale mixture (10) by grinding coal or a mixture of coal and petroleum coke as a solid carbon carrier and mill scale as Zundermaterial (7) in a mill (2), in particular a vertical roller mill with a built-in classifier (3) can be produced.

Fuel system according to claim 4, characterized in that the fuel-scale mixture (10) has a proportion of scale in the range between 0.5 and 55%, preferably between 5 and 15%.

Fuel system according to claim 4 or 5, characterized in that the fuel-scale mixture (10) contains scale material having an iron content in the range of 30 to 80%.

Fuel system according to one of claims 4 to 6, characterized in that the starting material for the fuel-scale mixture (10) is a Zundermaterial having a water content of 2 to 15% and an oil content between 0 and 5% and a grain size up to 50 mm is provided .

Method for producing and supplying a fuel system, in particular according to one of Claims 1 to 7, in which at least one carbon carrier (6) is ground in a mill (2) and fed to a blast furnace (28) by blow molding (27) in the PCI process. characterized in that a prereduced iron material (7) is admixed with the carbon carrier (6) and fed to the blast furnace (28) through the blow molds (27).

A method according to claim 8, characterized in that as carbon support (6) carbon, a coal mixture, a mixture of coal and petroleum coke, plastics or a suspension of coal and / or plastics and oil and as prereduced iron material (7) scale material, for example mill scale, in a mill (12) are subjected to a common grinding process and as a fuel-scale mixture (10) after a screening and separation from a carrier gas (9), via a conveying and distributing means (20 to 26) via the blow molds (27) is blown into the blast furnace (28).

A method according to claim 8 or 9, characterized in that the solid carbon carrier (6) via a coal allotment (15) and the Zundermaterial (7) via a scale allocation (14) of a conveyor (5) supplied in a predetermined mixing ratio and as a feed mixture (4) are fed to the mill (2).

A method according to claim 9 or 10, characterized in that the mill (2) a feed mixture (4) with a proportion of tinder in the range between 0.5 and 55%, in particular between 5 and 15% applied and subjected to a mill drying. Method according to one of claims 8 to 11, characterized in that the grinding in an inertized or air-driven mill (2) is carried out and for grinding an inert gas (9), eg blast furnace gas or blast furnace waste gas, or hot air, which in a hot gas generator ( 11) is heated to the required temperatures is supplied.

Method according to one of claims 8 to 12, characterized in that the feed mixture (4) Zundermaterial (7) with a water content in the range of 2 to 15%, an oil content between 0 and 5% and a grain size of up to 50 mm and mixed with a fuel raw material or a fuel raw material mixture as a carbon carrier to a blow ready fuel system (10) in a vertical roller mill (2) with separator (3) will mow.

Method according to one of claims 8 to 13, characterized in that as a ready-to-blow fuel system (10) a fuel-scale mixture of about 85% fuel, in particular coal, and about 15% mill scale produced in a grinding-visual process and pneumatically the blow molding ( 27) is supplied.

Method according to one of claims 8 to 14, characterized in that the einblasfertigige fuel system has a grain size of 50 to 80% <90μ. Method according to one of claims 8 to 15, characterized in that the einblasfertigige fuel system (10) is supplied pneumatically with the aid of a conveying gas or a gas mixture, in particular nitrogen, from a compressed gas container (21).

Method according to one of claims 8 to 16, characterized in that the Einblasfertigige fuel system (10) via a continuous Einschleussystem, in particular in the form of at least two feed containers (22, 23), and a distribution device, in particular a distribution container (24), and injection lines (26) is supplied to the blow molds (27).

Plant for producing and supplying a fuel system via blow molding (27) for pig iron production in the blast furnace (28), with a mill (2), allocating means (14, 15) for the feed material to be milled and feed means (21 to 26) to the blow molds (27) 27), in particular for carrying out the method according to one of claims 8 to 17, characterized in that in front of the mill (2) means (5) for producing a feed mixture (4) from a prereduced iron material, in particular Zundermaterial (7), and a carbon support (6), in particular coal, is arranged.

Installation according to claim 18, characterized in that according to one of the mill (2) and an intregrierten

Classifier (3) downstream filter (12) and before a a silo (20) for the in the mill (2) manufactured ready for blowing fuel-scale mixture as a fuel system (10) is arranged a further means for mixing.

Installation according to one of claims 18 or 19, characterized in that for a pneumatic supply of the blowing ready fuel-scale mixture (10) a continuous Einschleussystem, in particular in the form of at least two feed containers (22, 23), and a distribution device, in particular in shape a distribution container (24) are provided, from which the fuel-scale mixture (10) passes by means of positive pressure or by gravity into the injection lines (26) and the blow molds (27).

Installation according to one of Claims 18 to 20, characterized in that the supply of the fuel-scale mixture (10) takes place by means of dense or thin-flow conveying.