DE102008060774B4 - Scrap heating process and devices in steelmaking plants - Google Patents

Abstract

Scrap preheating process in steelmaking plants, wherein the kiln exhaust gases (2) from the smelting unit (1) are directed into the preheater (3), flow through the scrap column (10) and preheat it by means of sensible heat of the kiln exhaust gases (2), after which the preheater exhaust gases (6) move to Leaving the preheater (3) without thermal aftertreatment of a deposition chamber (8) are supplied, characterized by a combined Schrottvorwärmungsprozess in the preheater (3), which has the following main features: - Guiding the Schrottvorwärmungsprozesses without temperature drop below 800 ° C in the entire scrap column (10) - External heat supply through burner systems (4) in the preheater (3).

Description

Technical area

The invention relates to a Schrottvorwärmungsprozess and facilities in steelmaking plants, the kiln exhaust gases are passed from the melting unit in the preheater, flow through the scrap column and heat them by means of sensible heat of the kiln exhaust gases, after which the preheater exhaust gases through the exhaust duct leave the preheater and in the exhaust treatment plant in the they are treated chemically or thermally, be passed on.

Since scrap is processed mainly in electric arc furnaces for steel, the invention with reference to an electric arc furnace with an integrated preheating shaft (further called preheater) is explained. These plants belong to the field of electric steelmaking, which is a branch of the steelmaking industry. The invention is based on a new procedural mode of operation of the scrap preheating, as well as on constructive adjustments of the preheater to the combined Schrottvorwärmungsprozess. The process engineering operations of this invention relate to the natural sciences of physical heat transfer and chemical generation of pollutants.

Prior art with references:

• – ungleichmäßige Schrottvorwärmung führt zu einer unvollständigen Verbrennung der organischen und anorganischen Bestandteile in der Schrottsäule
• – unvollständige Schrottvorwärmung ergibt eine begrenzte Verringerung der Schmelzzeit und eine unbefriedigende Energiebilanz
• – die kalte Schrottsäule am Vorwärmeraustritt bewirkt einen hohen Schallpegel bei Schmelzbeginn
• – durch den Temperaturabfall in der Schrottsäule unter 800°C entstehen unterschiedliche Schadstoffarten, z. B VOC, NO_x, PCDD/F
• – die entstandenen Schadstoffe im Vorwärmerabgasstrom müssen anschließend durch eine Nachverbrennung in spezieller Nachverbrennungskammer zersetzt werden
• – durch die zwangsweise rasche Abkühlung geht die Enthalpie des Vorwärmerabgasstroms nutzlos verloren

Scrap preheating in a scrap heating plant integrated in the EAF (electric arc furnace). These systems are known as finger shaft furnaces in electric steel production. They use effectively and almost without loss the sensible heat of the kiln exhaust gases. Seen metallurgically, the preheating process is optimally adapted to the melting phases of the electric arc furnace. The temperature drop in the scrap column, especially in the start-up phase of the scrap preheating, produces various types of pollutants that pollute the air and the environment. The pollutants produced in the preheater exhaust gas stream after scrap preheating are thermally decomposed in a post-combustion process, which requires the installation of an afterburner chamber. Subsequently, the preheater exhaust gases must be cooled rapidly, within a few seconds, in order to prevent a regression of the pollutants. When looking at the scrap-preheating process of this kind, it turned out that the EAF with scrap preheating has an increased organic concentration in the preheater exhaust gas. This results from the, due to the process, low exhaust gas temperature through the heat exchange within the scrap column, whereby the organic components in the scrap (oil, plastics, etc.) only evaporate but are not destroyed. These include volatile organic hydrocarbons and the precursors for dioxins and furans (PCDD / F). These must turn thermally at temperatures of min. 800 ° C are decomposed, which requires an additional heat input into the Schrottvorwärmungsprozess. Due to the unfavorable sequence of thermal and chemical processes during the preheating of the scrap, the degree of utilization of the scrap heating process drops significantly. The scrap heating process with a scrap heating unit integrated in EAF has the following disadvantages:

• Uneven scrap preheating leads to incomplete combustion of the organic and inorganic components in the scrap column
• - incomplete scrap preheating results in a limited reduction of the melting time and an unsatisfactory energy balance
• - The cold scrap column at the preheater outlet causes a high level of sound at the onset of melting
• - Due to the drop in temperature in the column below 800 ° C different types of pollutants, z. B VOC, NO _x , PCDD / F
• - The resulting pollutants in the preheater exhaust gas stream must then be decomposed by post-combustion in a special post-combustion chamber
• - Due to the forced rapid cooling, the enthalpy of the preheater exhaust gas flow is useless lost

These are the reasons that currently the finger-shaft furnace finds a limited use. 01 ,

• – Verringerung der Schadstoffbildung durch partielle Schrottvorwärmung
• – Reduzierung des Schallpegels während der Schrotteinschmelzung
• – Verzicht auf eine Nachverbrennung der Vorwärmerabgase

The scrap-heating process according to published patent application DE 103 55 549 A1 from 06.25.2005, is a variant of the finger-pit furnace that provides a partial scrap warming and batching in the EAF. It is also one of the integrated scrap heating systems and largely solves the following problems:

• - Reduction of pollutant formation by partial scrap preheating
• - Reduction of the sound level during the smelting of scrap
• - Abandonment of afterburning of the preheater exhaust gases

By solving these problems, however, new ones have emerged that are difficult to reconcile with metallurgical processes of the electric arc furnace. Partial charging into the smelting unit, complex scrap preparation and complicated scrap logistics make the melting process in such plants difficult. This scrap heating plant is the most modern today of its kind. A system is currently in use worldwide. 02 ,

• – vollständige Schrottvorwärmung im Vorwärmerabgasstrom
• – geringer Schallpegel durch die vollständige Schrottvorwärmung

In the charging system integrated scrap heating systems. These systems are also known as "continuous scrap heating systems". The best known of this group is the "Consteel plant". These scrap preheating plants solve the following problems of scrap preheating:

• Complete scrap preheating in the preheater exhaust stream
• - Low sound level due to complete scrap preheating

• – Der lange Vorwärmer mit dem Schrottförderer stellt technisch ein großes Problem beim Betrieb diesen Anlagen dar
• – die Wärmeverluste auf der langen Strecke des Vorwärmers sind erheblich
• – Anlagen dieser Art erfordern eine Nachverbrennung der Vorwärmerabgase
• – Die aufwendige Schrottvorbereitung und Schrottlogistik sind noch ausgeprägter als bei Anlagen gemäß Offenlegungsschrift DE 103 55 549 A1

These systems have serious disadvantages that far exceed the benefits of this system.

• - The long preheater with the scrap conveyor technically represents a major problem in the operation of these plants
• - The heat losses on the long route of the preheater are significant
• - Plants of this type require afterburning of the preheater exhaust gases
• - The elaborate scrap preparation and scrap logistics are even more pronounced than in systems according to published patent application DE 103 55 549 A1

From a metallurgical point of view, the electric arc furnace is constantly in the melting phase, which is difficult to reconcile with the melting process. For these reasons, such systems are only used to a limited extent worldwide. 03 - 04 ,

• – ungleichmäßige Schrottvorwärmung
• – Bildung von verschieden Schadstoffen, begleitet von einer starken Rauchentwicklung
• – Notwendigkeit einer Nachverbrennungskammer
• – erzwungene rasche Abkühlung der Vorwärmerabgase
• – komplizierte Abgasleitungen und Schrottlogistik

Scrap preheating plant outside the smelting unit. These systems use the sensible heat from the kiln exhaust gases for scrap preheating in special preheating chambers installed outside the EAF. These systems work independently of the process flow of the EAF and are therefore very flexible in operation. Plants of this type do not solve any problem of scrap preheating completely, but have the following problems:

• - Uneven scrap preheating
• - Formation of various pollutants, accompanied by a strong smoke
• - Need for a post-combustion chamber
• - forced rapid cooling of the preheater exhaust gases
• - complicated exhaust pipes and scrap logistics

In particular, the long and complicated hot gas lines, special hoods and high-temperature flaps make the preheating of scrap very maintenance-intensive and the energy balances often prove to be a "zero-sum game". Another problem of this system is the service life of special heat-resistant scrap baskets and their logistics in the steelworks. Due to the high operating costs and the high emissions, these systems are also currently only used to a limited extent. 05 ,

• – ungleichmäßige Schrottvorwärmung im speziellen Schrottkorb von oben nach unten
• – unvollständige Schrottvorwärmung und dadurch eine begrenzte Verringerung der Schmelzzeit und eine unbefriedigende Energiebilanz
• – die kalte Schrottsäule am Vorwärmeraustritt bewirkt einen hohen Schallpegel zu Beginn der Einschmelzphase
• – durch den Temperaturabfall in der Schrottsäule unter 800°C entstehen unterschiedliche Schadstoffarten, z. B VOC, NO_x, PCDD/F, begleitet von einer starken Rauchentwicklung

Autonomous scrap heating plant. The development of scrap preheating began with these plants in the 50-60s. First, they were used as drying equipment to rid the scrap of ice and snow. Drying systems are used when the scrap is preheated to approx. 200-400 ° C. Later, the drying facilities had become scrap heaters. Plants of this type use fossil fuels, mainly natural gas, as their energy source and have all the known problems of scrap preheating.

• - Uneven scrap preheating in the special scrap basket from top to bottom
• - incomplete scrap preheating and thereby a limited reduction of the melting time and an unsatisfactory energy balance
• - The cold scrap column at the preheater outlet causes a high level of noise at the beginning of the melting phase
• - Due to the drop in temperature in the column below 800 ° C different types of pollutants, z. B VOC, NO _x , PCDD / F, accompanied by heavy smoke

In addition, the systems also have the problem of the short life of the heat-resistant scrap baskets, as in the scrap preheating plant outside of the melting unit on. As a result of these problems, the systems are hardly used today. 06 ,

The problems underlying the invention

• • Die Schrottvorwärmung in Anlagen, welche die fühlbare Wärme der Ofenabgase oder fossile Energie nutzt, erfolgt nur teilweise. Sie ist durch einen starken Temperaturabfall und hohe Temperaturdifferenz im Verlauf der Schrottsäule vom Ofenabgaseintritt bis zum Vorwärmerabgasaustritt gekennzeichnet.
• • Da der Schrott in den Vorwärmungsanlagen nicht homogen vorgewärmt wird, ergibt sich eine begrenzte Verringerung der Schmelzzeit und als Folge eine nur geringe Elektroenergieeinsparung in Elektrolichtbogenöfen.
• • Der relativ kalte Schrott an der Vorwärmerabgasaustrittsstelle bewirkt beim Schrotteinschmelzen im EAF einen hohen Schallpegel, der derzeit weit über 120 dB liegt. Dieser Umstand bringt erhebliche Schwierigkeiten und Kosten beim Personal- und Lärmschutz mit sich.
• • Durch den Temperaturabfall in der Schrottsäule unter 800°C und als Folge ein unvollständiges Verbrennen von Fremdstoffen (organische und anorganische Substanzen) in der Schrottsäule, entsteht eine starke Rauchentwicklung, was zu Bildung von verschiedenen Schadstoffe, wie z. B. CO, VOC, PCDD/F in den Vorwärmerabgasen führt.
• • Die entstandenen Schadstoffe in den Vorwärmerabgasen müssen durch Erhitzung des Vorwärmerabgasstroms auf über 800°C, meist in zusätzlichen Nachverbrennungskammern, thermisch zerstört werden. Durch die notwendige Nachverbrennung der Vorwärmerabgase wird ein Teil der gewonnenen Energie der Ofenabgase an den Nachverbrennungsprozess wieder zurückgegeben. Aufgrund der großen Abmessungen der Nachverbrennungskammer und Undichtigkeiten zwischen dem Vorwärmer, dem Abgaskanal und der Nachverbrennungskammer entstehen hohe zusätzliche Wärmeverluste.
• • Um den „De-Novo Synthese-Prozess”, Rückbildung von Schadstoffen bei langsamer Abkühlung zu vermeiden, müssen die Vorwärmerabgase nach der Nachverbrennung innerhalb von wenigen Sekunden durch spezielle Kühler rasch abgekühlt werden. Dadurch kann die Enthalpie des Vorwärmerabgasstroms in Wärmeaustauscheinrichtungen nicht genutzt werden und geht nutzlos verloren.

The problems of the scrap heating process and its equipment have arisen in the steelmaking industry in the field of scrap preheating of electric arc furnaces (EAF integrated scrap preheating plants) and scrap preheating facilities (autonomous scrap preheating plants integrated outside the smelting plant and in the charging system). Since the active use of scrap heating in the steelmaking industry, and especially after the introduction of the legal guidelines for exhaust emissions of pollutants in exhaust gases, the following problems have arisen in the scrap heating process and scrap preheater facilities:

• • Scrap preheating in plants that uses the sensible heat from kiln exhaust or fossil energy is only partial. It is characterized by a strong drop in temperature and high temperature difference in the course of the scrap column of Furnace exhaust gas inlet marked up to preheater exhaust outlet.
• • Since the scrap is not preheated homogeneously in the preheating systems, there is a limited reduction of the melting time and as a result, only a small saving in electrical energy in electric arc furnaces.
• • The relatively cold scrap at the preheater exhaust exit point causes a high sound level when scrap melting in the EAF, which is currently well over 120 dB. This circumstance brings considerable difficulties and costs in personnel and noise protection.
• • Due to the temperature drop in the scrap column below 800 ° C and as a result incomplete burning of foreign substances (organic and inorganic substances) in the scrap column, a strong smoke, resulting in the formation of various pollutants, such. B. CO, VOC, PCDD / F leads in the preheater exhaust gases.
• • The resulting pollutants in the preheater exhaust gases must be thermally destroyed by heating the preheater exhaust gas flow to over 800 ° C, usually in additional afterburner chambers. As a result of the necessary post-combustion of the preheater exhaust gases, part of the energy recovered from the kiln exhaust gases is returned to the post-combustion process. Due to the large dimensions of the post-combustion chamber and leaks between the preheater, the exhaust duct and the post-combustion chamber, high additional heat losses occur.
• • In order to avoid the "de-novo synthesis process", the reduction of pollutants during slow cooling, the preheater exhaust gases must be rapidly cooled after a few seconds by special coolers. As a result, the enthalpy of the preheater exhaust stream in heat exchange devices can not be used and is lost useless.

solution

The problems of the Schrottvorwärmungsprozesses and their facilities in Stahlerzeugurigsanlagen can be solved in terms of process technology with the characterizing features of claim 1 and with the characterizing features of the devices according to claim 9. The solution to the problems is described by the following process and equipment features:

Process characteristics:

• • In order to avoid the temperature difference and a temperature drop below 800 ° C in the scrap column, the scrap heating process takes place in a combined form. From the kiln exhaust gas entry point to the preheater exhaust exit point on the preheater, the scrap column is preheated on the one hand by the sensible heat of the kiln exhaust gas flow; in the middle region and at the preheater exhaust outlet of the preheater, on the other hand, the scrap preheating process is additionally assisted by external heat supply.
• • The external heat supply to the preheater via fuel-oxygen burner systems, preferably gas-oxygen burner systems are used. Alternatively, liquid fuel can also be used. To limit the volume of preheater exhaust gases in the preheater, gas-air or liquid-fuel-air-burner systems are not to be used in the combined scrap-preheating process.
• • The external heat supply of the burner systems takes place in a stepped form, which is dependent on the temperatures in the individual thermal sections.
• • In order to control the graded heat supply of the burner systems, a temperature detection system is provided on the preheater.
• • To ensure complete combustion of the organic and inorganic substances, the burner systems at the preheater are operated at maximum power with oxygen excess at the beginning of the scrap preheating. In a very short time (within one minute), a temperature of 850-1000 ° C is reached in all areas of the preheater.
• • After reaching a temperature of over 850 ° C in all areas of the preheater, the burner systems are controlled individually, depending on the temperature in the thermal section. Alternatively, the burner power can be controlled by a timer program.
• • The preheater exhaust gases in the combined scrap-preheating process must be subsequently subjected to no costly thermal treatment in a post-combustion chamber due to the high temperatures and the low-emission preheating exhaust gas stream. The preheater exhaust gases are fed to the reaction and deposition chamber, where they are treated chemically, in the form of CO reactions with oxygen, and at the same time a coarse-grained dust separation takes place.
• • After the preheater exhaust gases leave the reaction and separation chamber, the low-emission preheater exhaust gases can be fed to the heat exchanger and do not require rapid cooling by a special Cooler. In heat exchange devices, the preheater exhaust gases can be cooled at any rate and the enthalpy of preheater exhaust gases used for industrial purposes, usually for preheating industrial gases.

Features of the facilities:

• • The entire preheater is designed in the form of a thermal vessel, consisting of individual thermosections, for a continuous temperature of up to 1000 ° C. The water-cooled thermal sections are protected by wear plates or panels against scrap impacts and non-return flames.
• • For external heat supply, gas-oxygen burner systems are preferably used on the preheater between the thermosections. Alternatively, liquid fuel can also be used. The burner systems are arranged distributed uniformly over the entire circumference according to the geometric shape of the preheater.
• • The preheater is made of individual thermal sections that are built on top of each other. The thermosections are interchangeable.
• • The shaft shape from the embodiment is irrelevant. For the preheater any geometric shape is conceivable that meet the requirements of the combined Schrottvorwärmungsprozesses.
• • The burner systems have separate controls, they are controlled by the temperature measuring system depending on the temperature in the thermal section.
• • Temperature measuring systems are provided at every thermo section and at the preheater outlet.
• • The post-combustion chamber is replaced by the reaction and separation chamber, the preheater exhaust gases are fed to the heat exchangers instead of the radiator.

Advantageous Effects of the Invention:

• • The scrap preheating in the preheater takes place completely, without temperature drop and temperature difference in the scrap column, in the temperature range of 800-1000 ° C.
• • Homogeneous preheating of the scrap column significantly reduces the power-on time (elec- trical energy injection time required to completely melt the scrap metal), thus reducing the total Tap to Tap time (time from tapping to smelting of the smelting unit).
• • Due to the increased temperature of the scrap metal in the entire scrap column, the sound level drops below 120 dB during the power-on time. This has a positive effect on the staff and allows a standard design of the soundproofing equipment of the smelting unit.
• • In the preheater there is complete combustion of the organic and inorganic components in the scrap column. A synthesis of the various pollutants in the scrap column is largely suppressed. By this measure, the legal guidelines for the exhaust emission levels of pollutants in the context of conventional electric arc furnaces (electric arc furnaces without facilities of scrap preheating) are achieved.
• • The exothermic reactions of complete combustion of organic and inorganic substances in the preheater contribute positively to the heat balance of the electric arc furnace.
• • Due to the largely suppressed synthesis of pollutants, such. As CO, VOC, PCDD / F, post-combustion of preheater exhaust (heating the preheater exhaust gas flow above 800 ° C) is omitted. The need for an additional post-combustion chamber is eliminated.
• • The compact preheater and the design of the entire system without post-combustion chamber significantly reduce energy losses. These are caused by radiation of heat from the hot device surfaces to the environment and false air aspiration from the leaks between the preheater and the exhaust treatment system.
• • As a consequence of the suppressed synthesis of pollutants, there is a limited "de-nova synthesis" (regression of pollutants) under environmental standards.
• • The preheater exhaust stream may be cooled at any rate during the combined scrap preheating process. Thereby, the preheater exhaust gas stream can be used in heat exchange devices for commercial purposes.
• • The exhaust gas treatment plant can be designed as with conventional electric arc furnaces (without scrap preheating).
• • The invention allows to make the preheater for the combined scrap heating process without much investment. Even existing scrap preheating plants of various types can be adapted to the combined Schrottvorwärmungsprozess without great effort.

In the appendix of this specification, sketches and pictures representing the prior art and embodiments which explain the invention are attached.

Show it:

1 , a simplified sketch of scrap preheating in a prior art scrap preheating system known as EAF, known as a finger well furnace,

2 , an excerpt from the published patent application DE 103 55 549 A1 of 2005.06.23 a scrap preheating plant according to the prior art,

3 , a simplified picture of integrated in the charging system Schrottvorwärmungsanlagen state of the art, also known as "continuous scrap heating systems",

4 , a simplified picture of the charging system incorporating scrap heating systems according to the state of the art, also known as the "Consteel system",

5 , a simplified picture of a scrap heating plant outside the furnace of the prior art,

6 , a simplified picture of a prior art autonomous scrap preheating plant,

7 , a simplified overall sketch of the scrap heating process and facilities in steelmaking plants according to the invention,

8th , a simplified sketch with details of the scrap heating process and facilities in steelmaking plants according to the invention.

Embodiment FIG. 07-FIG. 08th

The in the smelting unit ( 1 ) resulting furnace exhaust gases ( 2 ) flow through the scrap column ( 10 ) of the preheater ( 3 ). The preheater ( 3 ) is the temperature drop in the scrap column ( 10 ) during the scrap-preheating process by the kiln exhaust gases ( 2 ), divided into four temperature zones. The preheater ( 3 ) according to the four temperature zones, in four thermosections ( 11 ). The thermal sections are protected by wear plates ( 12 ) against scrap impacts and flashbacks of the burner systems ( 4 ) protected. In the lower thermosection, the scrap is removed by the kiln exhaust gases ( 2 ) preheated rapidly to temperatures of 1200 to 900 ° C. In the course of the second thermal section, the furnace exhaust gases cool to below 800 ° C, further in the third and fourth thermal sections, a further cooling and finally the temperature of the kiln exhaust gases at the outlet of the preheater drops to up to 250-150 ° C. To the process of temperature drop in the scrap column ( 10 ), the scrap heating process is controlled by external burner systems ( 4 ) in the preheater ( 3 ) supported. Through the combined scrap heating process in the preheater ( 3 ), the kiln exhaust gases ( 2 ) are thermally and chemically influenced and thereafter process technically as Vorwärmerabgase ( 6 ) designated. The heat input of the burner systems ( 4 ) is gradually, depending on the temperature in the scrap column, by a temperature measuring system ( 5 ) controlled. To reduce the volume of preheater exhaust gases ( 6 ) in the preheater ( 3 ), it is intended to use mainly gas-oxygen burner systems. For reasons of process engineering and thermodynamics, air-fuel burner systems can not be used here. In the start-up phase of the scrap preheating, the burner systems are operated at full power with excess oxygen to a temperature above 800 ° C of the preheater exhaust gases in the entire scrap column ( 10 ) to reach. Rapid ramping of the temperature to over 800 ° C in the entire scrap column largely suppresses the formation of various pollutants (VOC, NO _x , PCDD / F). The preheater exhaust gases ( 6 ) leave the preheater ( 3 ) via the exhaust channel ( 7 ) without formation of the known pollutants and are in the reaction and Abscheidekammer ( 8th ). The preheater exhaust gases are treated chemically there, at the same time takes place a coarse dust separation. Thereafter, the low-emission preheater exhaust gases are the heat exchanger ( 9 ) and thus used economically.

LIST OF REFERENCE NUMBERS

1

smelting unit

2

furnace waste gases

3

preheater

4

burner systems

5

Temperature Measurement System

6

preheater

7

exhaust duct

8th

Reaction and separation chamber

9

heat exchangers

10

scrap column

11

Thermo sections

12

wear plates

13

Exhaust gas treatment plant

14

afterburning

15

cooler

Claims (15)

Scrap heating process in steelmaking plants, the kiln exhaust gases ( 2 ) from the smelting unit ( 1 ) in the preheater ( 3 ), the scrap column ( 10 ) and by means of sensible heat of the kiln exhaust gases ( 2 ), after which the preheater exhaust gases ( 6 ) after leaving the preheater ( 3 ) without thermal aftertreatment of a deposition chamber ( 8th ), characterized by a combined Scrap preheating process in the preheater ( 3 ), which has the following main features: - Guiding the scrap heating process without temperature drop below 800 ° C in the entire scrap column ( 10 ) - external heat supply through burner systems ( 4 ) in the preheater ( 3 ). Scrap preheating process according to claim 1, characterized in that the external heat supply in the preheater ( 3 ) via fuel-oxygen burner systems ( 4 ), preferably gas-oxygen burner systems occurs. Scrap preheating process according to claim 1 or 2, characterized in that the external heat supply in a stepped form, depending on the temperature in the scrap column ( 10 ), he follows. Scrap preheating process according to claim 3, characterized in that the heat supply in a stepped form by a temperature measuring system ( 5 ) is controlled. Scrap preheating process according to claim 2, 3 or 4, characterized in that the burner systems ( 4 ) are driven at maximum power at the beginning of the scrap heating process. Scrap preheating process according to one or more of claims 3 to 5, characterized in that after reaching a temperature of over 850 ° C in the entire scrap column ( 10 ) the burner systems ( 4 ) separately via the temperature measuring system ( 5 ) or controlled by a time program. Scrap preheating process according to claim 1, characterized in that the preheater exhaust gases ( 6 ) in the exhaust treatment plant ( 13 ) are chemically treated and a coarse-grained dust deposit in the deposition chamber ( 8th ) takes place. Scrap preheating process according to claim 7, characterized in that the low-emission and high-temperature preheater exhaust gases ( 6 ) after the reaction and separation chamber ( 8th ) without rapid cooling by a cooler ( 15 ) the heat exchanger ( 9 ). Apparatus for carrying out the scrap-heating process in steelmaking plants according to claims 1-8, consisting of a melting aggregate ( 1 ), a preheater ( 3 ), a scrap column ( 10 ) and an exhaust treatment plant ( 13 ), where the preheater consists of several identical thermosections ( 11 ), characterized in that each thermosection has openings for the burner systems. Devices according to claim 9, characterized in that the thermosections ( 11 ) of the preheater ( 3 ) Wear plates ( 12 ) have the preheater ( 3 ) against flashbacks of the burner system ( 4 ) protect. Apparatus according to claim 9, characterized in that for the combined scrap-heating process any geometric shapes of the preheater ( 3 ) are suitable. Apparatus according to claim 9, characterized in that for the combined scrap-heating process the burner systems ( 4 ) are designed as fuel-oxygen burner systems, preferably gas-oxygen burner systems. Devices according to claim 12, characterized in that the burner systems ( 4 ) to the geometric shape of the preheater ( 3 ) and the entire circumference of the preheater ( 3 ) are arranged evenly distributed. Devices according to claim 9, characterized in that at each thermosection ( 11 ) a temperature measuring system ( 5 ) is provided. Apparatus according to claim 9, characterized in that the steelmaking plant does not produce any post-combustion chamber ( 14 ) for the thermal decomposition of pollutants and no cooler ( 15 ) for rapid cooling of the preheater exhaust gases ( 6 ) owns.

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