FUTURE-ORIENTED OXYGEN STEEL PRODUCTION · CONTENT 23Future-oriented oxygen steel production...

FUTURE-ORIENTEDOXYGEN STEEL PRODUCTION FUTURE-ORIENTEDOXYGEN STEEL PRODUCTION

STEELMAKING

SteelmakingSMS DEMAG

2

SMS Demag, a synonym for leadingknow-how and long-term solutions forthe entire process chain of metallurgicaltechnology and steel production.

Planning, project engineering, design anddelivery, as well as operator training andthe supply of metallurgical know-how foran optimised sequence of production inintegrated steel mills, characterise thewide range of equipment and servicesoffered by SMS Demag.

The constant further development of all steelmaking modules and processsteps forms the basis for optimised steelmill design concepts for the enhance-ment of investment profitability.

Extensive relations with reputed steelmill users worldwide and with nationaland international research institutionscontribute considerably to the successfulaccomplishment of this aim.

Engineers with ample experience in allpertinent disciplines and utilising themost advanced data-processing tech-niques are constantly engaged in trans-lating the process parameters into opti-mum module and component designs.

Steel refining in a converter is an im-portant link in the chain of interrelatedproduction steps in the manufacturingand further processing of steel.

The advent of the oxygen blowing prac-tice in the fifties marked a giant stepahead and a new epoch in steelmaking.The basic practice was the blowing ofpure oxygen on top of the metal bath in the converter vessel. The resultingquick conversion of material and energywere the basis for success.

The 30-t vessels of the mid-fifties quicklybecame production units capable of hold-ing up to 400 t of melt weight and yield-ing 600–650 tonnes per hour.

Optimisation, further development, andinnovations led to increased productionand tangibly contributed to qualityimprovements and the cost effectivemanufacture of high-quality products.

FUTURE-ORIENTEDOXYGEN STEEL PRODUCTION FUTURE-ORIENTEDOXYGEN STEEL PRODUCTION

CONTENT

2 3 Future-orientedoxygen steel production

4 9 Converters

10 11 Change vessel converters

12 13 Blowing lances

14 15 Slag splashing and bottomstirring

16 17 Sublances

18 19 Waste gas analysisSonicmeter

20 23 AutomationSlag retaining devices

24 25 Relining equipment

26 27 Dust collection, gas cleaningand gas recovery

28 29 Erection and commissioning

30 31 SMS Demag converter equipment

3


4

CONVERTERSCONVERTERS

For the production of quality steels, theLD converter with its oxygen top blowinglance and vessel bottom tuyeres for inertgas stirring has found general accep-tance.

Special steels are chiefly made in MRP(Metal Refining Process) or AOD (ArgonOxygen Decarburisation) converters inconjunction with electric arc furnaces andvacuum degassing facilities.

Depending on the blowing method,whether LD, AOD or MRP (with or with-out top blowing lance), the shapes of theconverter vessels are more or less slen-der or big-bellied, with symmetrical ornon-symmetrical vessel top cones orwith integral or replaceable bottoms.

Special attention is paid in the designingof a converter to the service life of theconverter vessel and of the trunnion ring.The material of which a converter vesselis made is subject to extreme thermalstressing during the steelmaking process.The temperatures in the vessel wallsattain about 420 °C and in the trunnionrings about 210 °C. This implies loadvalues not far below the yield strength of the materials.

Thomas Converter 1879

– Short bottom life– Small heat size– High N-content in steel– Slopping– Pollution– Low scrap consumption

LD converter 1948

– High productivity– Low N-content– Low pollution– Slopping– Remote from

steel/slag equilibrium

QBM/Q-BOP 1968

– Low productivity– Low N, P, S, C, O– Low (FeO) in slag– No slopping– Low pollution– Low scrap rate

AOD 1969

– Low gas con – Low sulphur– Better yield

Heat size [t] Height [mm]

Volume [m3] Diameter [mm]

9810

8570

7862

6050

300

220

140

50

268 117 50 1785 2470 3320

31752930200068181

68006815

8720375

11080

200 88 2263

Developments in respect of convertervessels and blowing processes.

LD converter volumes.

5

Comb-blowing 1977

– Bottom and top-blowing with O2

– Lime injection– Post-combustion– Higher scrap rate

KMS converter 1978

– Bottom and top-blowing with O2

– Coal injection and/orscrap preheating

– Lime injection– Post-combustion– Very high scrap rates– Large amount of

valuable offgas

LD-CB 1981

– Increased yield– Savings in ferro-alloy

and fluxes– Reduction of

inclusions

MTBI (MWH) 1981

– Higher yield– No slopping– Additive savings

MRP 1983

– High mixing energy– Low carbon content– Low gas content– Very low sulphur– Fewer inclusions

tent


Volume [m3] Diameter [mm]

74306620

57505548

4090

3766

3080

62.5

75105

5035

15

8

5

29.7 17.4 4.3 1960 2760 4200 55005000276019602.26.848


Volume [m3] Diameter [mm]8

6345

4300

4570

3890

3630

80

15

20

10

7

10 2220152511453.836

13601225

3.62

MRP converter volumes. AOD converter volumes.


6


SMS Demag now uses a highly tempera-ture-resistant, fine-grained structuralsteel specially developed by a reputedGerman steelmaker.

This new grade offers a higher yieldstrength than, for instance, German steelgrades 13 CrMo 4–5 or 10 CrMo 9–10 or American steels ASTM A387, grade12 and grade 22, and thereby significantlyimproves the service life of the convertervessels and the trunnion rings.

The yield strengths of the new material,as well as the chemical analysis andmechanical properties, are comparedwith the conventional steels in the dia-grams/tables.

Vessel

420 °C790 °F

310 °C590 °F

380 °C720 °F

150 °C300 °F

Trunnionring

180 °C360 °F

210 °C410 °F

125 °C240 °F

180 °C360 °F

C Si MN P S Cr Ni Mo V

(%) (%) (%) (%) (%) (%) (%) (%) (%)

0.17 0.25 0.92 0.19 0.003 0.70 1.90 0.52 0.093

CHEMICAL COMPOSITION

750

700

650

600

550

500

450

400

350

300

250

200

150

100

50

0

0.2%

yiel

d po

int

in N

/mm

0 50 100 150 200 250 300 350 400 450 500 550 600 650 700

XABO 690Actual value

XABO 690Minimum value

P356NH

13CrMo4–5

10CrMo9–10

16Mo3

P275NH

Temperature in °C

Minimum yield strength of heat-resisting steel depending on temperature

Temperatures in the vesselwall and the trunnion ring.

Yield strengths.

7

0.2% yield strength Tensile Elonga- Impact strength tion energy

in N/mm2 in N/mm2 in % in J

Rt 400 °C 500 °C 550 °C 600 °C Rt Rt –20 °C

724 588 532 483 302 803 19.8 151

MECHANICAL PROPERTIES

Charging of a converter vessel.


8


Other noteworthy features of the SMS Demag converter system are thereplaceable bottom, the cooling of thevessel top cone, and the specially devel-oped drive, which allows 100% torqueequalisation among the drive trains and freedom from backlash in the gearflanks when the converter is in its work-ing position.

Another important criterion for trouble-free operation is the method of vesselsuspension in the converter trunnionring.

Two fixing systems have proved theirworth in the course of many years here:

The lamella packs for stationaryconverters.The tensioning elements for change-vessel converters.

The essential feature of the fixing sys-tems is the fact that the vessels are ableto expand to the greatest possible extentwithout any hindrance.

These designs locate and center the ves-sels troublefree in every tilting positionand without any backlash in the trunnionring, thereby ensuring a uniform loadingof the latter.

Converter drive. MRP converter.

Lamella packs.

Vessel tendons.

9

Suspension for stationary converters.

LD converter. AOD converter.

Suspension for change-vessel converters.


10

CHANGE-VESSELCONVERTERSCHANGE-VESSELCONVERTERS

The change-vessel converter design represents an alternative to equipping a meltshop with several permanently installed converters, each with all of thenecessary ancillaries for a steelmakingstation, such as bins, fume exhaust sys-tem, lance equipment, ladle and slagtransfer cars, etc.

The advantage of the change-vessel typeis that it is possible to lift the vessel outof the trunnion ring when the refractorybrickwork is eroded and replace it byanother vessel newly lined in an off-con-verter rebricking area. Vessel changingtimes range between two and 16 hours

(approx. six hours on average). Vesselchanging is carried out when the convert-er is down for scheduled maintenanceanyway. Accordingly, the annual capacityof the change-vessel converter is equalto a conventional one-two operation.

The investment costs for the additionalequipment necessary for the change-vessel type, such as vessel changing car,wrecking and rebricking stand as well aswaiting stand for the newly lined vessels,are relatively low compared with thecosts of an additional, fully equipped con-verter operating station.

Change-vessel converter facility at HKM.

Change-vessel converter facility at HKM.

11

Illustration of a change-vessel facility.


12

BLOWING LANCESBLOWING LANCES

Oxygen blowing lances decisively in-fluence the process of decarburisation.

The blowing lances are exposed toextreme stresses in the reaction space.Steel and slag skulling on the lances is frequent. The oxygen exits from thelance tip nozzles at high velocities, whichis conducive to rapid wear and negativelyinfluences the shape of the oxygen jet.

One consequence is that lance changingis a necessity.

In conventional lance systems, the mediaconnection pipes are generally an integralpart of the lance. Thus, lance changingmeans the unbolting of numerous flangesand the separate disconnection of themedia supply and return hoses.

Lance changing often takes up to sixhours as safety regulations prescribe thatwork in the area above the converter ispermitted only during blowing breaks.

SMS Demag, in close cooperation withThyssen Krupp Stahl AG, has developedand uses an automatic blowing lancesystem, which minimises the times re-quired for lance changing.

The characteristic features of the systemare a coupling bell integrated into thelance carriage and equipped with fixedmedia connections, and a specially con-figured coupling head on the lance.

Quick lance changing is ensured by amanipulator, which is arranged oppositethe blowing lance and which accepts anew lance before the changing operation.

For instance, lance changing in the oxygen steelmaking shop of Ispat takes10 minutes on average.

A C-hook can be used for lance removal and installation where structural steelspace restrictions do not allow the instal-lation of a manipulator.

Eroded nozzles. Lance tip.

13

Lance quick-changing rig at the Ruhrort Ispat works.

Illustration of quick-changing rig.

Chemical reactions. �


14

SLAG SPLASHING and BOTTOM STIRRINGSLAG SPLASHING and BOTTOM STIRRING

SLAG SPLASHING

Constant efforts at improving vessellining service lives have resulted in anumber of new developments, such aschanges in the chemical composition of the bricks and the coating of the bricklining with residual slag, which havefinally led to the present and widelyadopted Slag Splashing method.

This method means that a sharp jet of nitrogen is blown onto the slag thatremains in the converter vessel aftersteel tapping, to the effect that slag issplashed onto the converter vessel walls,adheres to the brickwork and forms aprotective layer on the refractory lining.

Slag adherence is significantly influenced by the chemical composistion and thewear resistance of the brickwork. Addi-tionally, the consistency of the slag playsan important role in this technique.

In general, the melter visually judges thecondition of the slag and decideswhether lime or dolomite should beadded to obtain the desired consistency.Appropriate process automation is anoth-er method of achieving the required slagcondition. The tests carried out duringthe past few years, chiefly in the USA,show that the service life of a vessel lin-ing on which slag splashing is additionallyemployed ranges between 10,000 and20,000 heats.

The nitrogen jet is injected by means of the existing oxygen lance, which isconnected to a separate nitrogen controlloop for the purpose. The lance traveldistance is adapted accordingly to enablethe lance to be lowered deeply enoughinto the converter vessel.

Slag splashing illustration.

Illustration of bottom stirring system.

15

STIRRING THROUGH THE

VESSEL BOTTOM

Bottom stirring in converter vessels wasdeveloped in the late seventies/earlyeighties. Steel bath agitation in a BOFvessel is chiefly produced by the energyinput of the jet of oxygen which hits thebath surface and by the energy of boil-ing, assisted by the formation of CO.CO formation is high during the main period of decarburisation in the jet im-pact area and in its immediate vicinity onthe bath surface. Dead zones, where the reaction potential is lower, exist in themarginal surface regions.

To achieve homogeneity of composition and temperature uniformity in the melt, it is expedient to inject inert gas, eitherargon or nitrogen, through the vesselbottom into the melt. The injected gasimproves bath agitation and conveys thecarbon to the oxygen impact area duringphases of low CO formation. The amountof injection gas varies in accordance withthe different phases of the steelmakingprocess. The amounts of iron containedin the slag are significantly reduced andhence the overall yield of the converter isimproved.

An additional crucial consideration inmodern process technology is a lowphosphorus content of the melt at theend of blow. The injection of stirring gasthrough the bottom during the steel-making process and post-stirring at theprocess end significantly contribute toachieving this aim. Special tuyeres whoseflow rates are separately variable are employed for the introduction of oxygenand inert gas.

Argon

ArN2

Nitrogen

Converter 2

Converter 1

Converter 3

Tuyere bricks.

P & l diagram.

Converter vessel bottom with media piping.


16

SUBLANCESSUBLANCES

Steelmakers have been quite familiar withsublance technology since the eightiesand have been using it as an integral partof automatic oxygen steel production.Nevertheless, SMS Demag sees furtherpotential for production enhancementand quality improvement in this field.

The use of industrial robots for probehandling has significantly shortened theintervals between successive measure-ments at the end of blow. The highmemory capacity of present-day robotcontrol systems makes it possible to task the robot with a variety of functionswhich positively influence the entireprocess sequence in respect of sample-taking and sample evaluation. One exam-ple is the Complete Ad-Hoc Analysis ofmelt samples taken with the help of asublance.

A system developed by SMS Demaguses a laser-based analyser to render itpossible to analyse within a minimum of time those elements which are mostimportant in the course of production.Upon extraction from the converter, theprobe tube is pulled by the robot fromthe sublance and conveyed to a sever-ing station where the sample is cut offwhile still inside the cardboard tube of

the probe. After this, the robot takes the probe with the cut face of the half-sample to the laser analyser. Contrary tothe conventional sample-analysis method,this technique does not require any spe-cial sample preparation for analysis.

The laser beam creates plasma on thecut surface of the sample. A spectrome-ter uses the radiation from the plasma todetermine the chemical analysis of theheat. Differences in the wave lengths ofthe plasma radiation from the individualelements indicate the amounts of car-bon, chromium, manganese, aluminium,cobalt, copper, molybdenum, nickel,phosphorus, sulphur, silicon, and titaniumcontained in the steel.

Reductions of up to seven minutes intap-to-tap time can be achieved throughthe use of this new technology, com-pared with the previous standard practiceof sample unpacking, sample dispatchingthrough a pneumatic tube system to thecentral laboratory, sample preparation,and spectral analysis.

Robot and laser analysis.

General view of sublance installation.

17

Fe II 201.0 nm

Fe II 193.2 nm

192 194 196 198 200

Wavelength/nm

Carboncontent:

1.527%

1.052%

0.611%

0.302%

0.048%

0.019%

Norm. Int. / a. U.

C I 193.1 nm

*1E4

6.00

4.00

2.00

0.00

Typical spectral lines.

Sublance in measuringposition; robot in waitingposition.

Robot with gripper.


18

WASTE GAS ANALYSISWASTE GAS ANALYSIS

Waste gas measurement is now an inte-gral part of most process control systemsin oxygen steel production.

In addition to a static model for the pre-diction of process events, waste gasmeasurement allows continuous obser-vation and control of the process in a dynamic model provided in conjunctionwith the sublance system.

The decrease in the decarburisation ratetowards the end of blow indicates whensublance measurement should be per-formed. It is thus possible to reliablyachieve the carbon content and the tem-perature target. The calculation of iron,manganese, phosphorus and sulphurslagging on the basis of the oxygen bal-ance makes it possible to tap and alloymost of the heats without having to takea random sample and await its analysisresults.

The rate of chromium combustion can beobserved by continuous analysis of thewaste gases and by automatic interven-tion in the blowing process. This is highlyimportant in respect of chromium slag-ging, above all in special steel productionin the MRP/AOD converter.

When decarburisation is nearing its end-point, the rates of oxygen and inert gasflow through the top blowing lance andthrough the bottom tuyeres can be con-trolled to meet the oxygen requirementas the decarburisation rate declines.

Waste gas analysisCO, CO2, O2

Infrared measurement

Waste gas flow

Vent.-deviceRestr.-deviceThermodyn. corr.

Weak points

– Time delay (30–40 s)– Add. measurements

for thermodyn. corr.– Waste gas flow

measurement– Only C- and

O2-balance

Dynamicprocessmodel

O2, T, PCO control

fromO2 and

E-balance

C, Cr, T,

dC dCr dT– – –dt dt dt

Weak points

– Time delay (30–40 s)– Appear until high

Ar flow– Short maintenance

interval (1–2 weeks)

– Only C- andO2-balance

Waste gas flow

Indirect fromtracer gas flow(Ar, He)

Waste gas analysisCO, CO2, O2, Ar,N2, H2, He

e/m – Measurement

Mass spectrometry

Conventional measurement

�( )( )( )

Waste gasMain pipeline

Waste gas analysis

CO CO2 O2

0.0% 0.0% 0.0%

Response time:0.5 s 0.5 s 0.5 s

Waste gas sample

Delivery pumps

Vol. approx. 0.5 l

Transport time: 2 sPreparation time: 23–26 sResponse time: 1.5 s

Delay time: 26.5–29.5 s

Restrictiondevice

Waste gaspreparation

Waste gas pipeline

Gas cooler

Coarsefilter

Dry finefilter

Processor

Waste gassample

Pressureconverter

Main pump

Measuringhead

Turbomolecularpump

Waste gas inlet Test gas inlet

� Waste gas analysisusing mass spectrometer.

Diagram of wastegas analysis.

Waste gas analysis usingindividual components. �

19

SONICMETERSONICMETER

Sound level measurement during steel-making in a converter serves to monitorthe formation of slag during the blowingoperation in order to simplify productionand augment the yield of the process asslopping (boiling over) is avoided.

During blowing, the sound level is in-fluenced by

slag formation during silicon removal,CO formation starting when maindecarburisation begins,CO formation declining at the end ofmain decarburisation.

The sonicmeter method, using an enve-loping curve, represents the containmentof the standard curve of the sound levelwithin a minimum/maximum designrange. This containment is monitored bysoftware specially developed for the pur-pose. Any overshooting or undershootingof the limits corrects the position of thelance and influences the formation ofslag.

The lance is lowered if the slag volumein the converter vessel is excessive. Thelance is raised if the slag volume is insuf-ficient. Reliable determination of the opti-mum frequency band for measurementof the sound level is contingent uponpreliminary testing of the noise emittedduring converter blowing. The tests areintended to make certain that no noisefrom external sources in the vicinity ofthe converter can corrupt the measure-ment results and that the requiredmicrophone is optimally positioned in thesound tube.

The use of sound level measurementallows control and adaptation of the

Si content (as an indicator of theamount of slag formed in the process)and of thedistance between the blowing lance and the bath according to changingoperating conditions.

120

110

100

90

80

70

60

50

40

30

20

10

0

Nor

mal

ized

sou

nd (

db%

)

Start window

Oxygen (Ncbm)

BloCon – Blowing control system

Sound measurement design

Expected sound level

Sound standard Sound mean varied Lower limit Upper limit

Upperlimit

Lowerlimit

Hard blowing, possible sparking

High slag development,possible slopping

Sublancemeasurement

Endpointblowing

0 1500 3000 4500 6000 7500 9000 10500 12000 13500 15000

Sound level measurement.


20

AUTOMATIONAUTOMATION

Automation during the manufacture ofsteel is no longer confined to processcontrol and process monitoring.

Ever more stringent customer demandsfor optimum steel grades and cost-effective steelmaking make it necessaryto employ systems which optimise theprocess as a whole and the processevents.

The systems are structured hierarchicallyas follows:

Level 0 – Field equipmentLevel 1 – MSR equipment, including visualisationLevel 2 – Process optimisation bymeans of process modelsLevel 3 – Production planning andmanagementLevel 4 and higher levels – Administrative functions

The SMS Demag automation systemsare able to cover all these needs. TheBloCon model is available on Level 2 forsteelmaking by the BOF process. TheBloCon model is based on the metallur-gical description of the blowing processof a BOF converter. It calculates themass and the thermal balance with thehelp of an optimisation algorithm.

The design of the model enables thecalculation of all charging materials con-cerned. BloCon supports all technologiesapplied to a modern BOF converter, suchas bottom stirring, sound measurement,offgas analysis, and the use of sublancemeasurement.

To mainframe and laboratory

Main control room Engineering station

Converter Lance Sublance Materials Cooling Day bins Dedusting

Lime5040

Ore 21136

Dolo224940

Dolo342850

Dolo342850

Sublance

Main lance

Dolo221081

Dolo341080

400

350

300

250

200

150

100

1200

1000

800

600

400

200

0

Lanc

e he

ight

ove

r ba

th in

cm

500

450

400

350

300

250

200

150

100

50

0

Lanc

e he

ight

ove

r ba

th in

cm

Stir

ring

gas

in N

m3 /m

inO

xyge

n flo

w r

ate

in N

m3 /m

in

0

0

10

8

6

4

2

04000

Sublance inblowmeasurement

Lance heightover bath

Bottom stirringNitrogen Bottom stirring

Argon

Blowing end

Argon flow rate

Oxygen blowing rate Sublance measurement

Nitrogen flow rate Lance height

Oxygen in Nm3

8000 12000 16000 20000

120

Blowing time in secs

240 360 480 600 720 840 960 1080 1200

a)

Example of an integratedautomation system Level 1 + 2.

Typical blowing pattern.

21

SMS Demag also offers the SecMetmetallurgical model, which was devel-oped for the production of special steelsin AOD/MRP converters and which cov-ers the particular needs of low-carbonaustenitic and ferritic steels.

Statistics reflecting heat data, tappingtemperatures, analyses, material con-sumption, etc., must be created and mustbe retrievable without delay to enable thequickest possible reaction to changingconditions.Customer specific require-ments in connection with steel gradesand lot sizes necessitate a higher produc-tion planning level to enable individualprocess events and the sequence ofmelts to be controlled. This encompassesall steps, from the supply of hot metal tothe sequence of conticasting ladles.

As a valuable aid for this purpose, SMSDemag offers a production planning andcontrol system (PPS), which has beenspecially developed for such steelmakingdemands.

It forms part of the company-wide man-agement and information system and hasinterfaces with Sales, Procurement,Material Practice, Logistics, and the subor-dinated Level 2 process computer sys-tems. On the basis of sales planning andcustomer orders received for finishedproducts, it is the objective of productionplanning and control to coordinate andmanage production in all steelmaking andsteel rolling areas for the purpose of ob-taining, within specified time scales, thetonnages and grades agreed with the cus-tomer.


22

AUTOMATIONAUTOMATION

CUSTOMER BENEFITS:

The benefits of a production planningand control system are reflected in thefollowing:

Production consistent with orders(even for small lots),Production for just-in-time delivery,Flexibility with regard to short-term orders,Satisfaction of the customers’ qualityrequirements in the melt, casting androlling sequences,Coordination of events in the melt-shop to permit long conticasting sequences,Efficient personnel assistance in theelimination of malfunctions.

The orders (melts) to be processed in asteel plant are plotted in a Gantt diagram.The diagram includes all processingstations (converters, alloying stations andcontinuous casting facilities) with speci-fied sequences and processing times.

The diagrams are updated dynamicallyby the process status messages fromthe Level 2 systems. The central coordi-nating function is able to intervene man-ually to change schedules and start newplanning computation runs.

Without flexible automation it is, fromthe present point of view, hardly possibleany longer to produce steel economicallyin conformity with today’s stringent quali-ty requirements.

Scheduling system. Production planning.

23

SLAG RETAINING SYSTEMSLAG RETAINING SYSTEM

Steelmaking process slags generally serveto absorb unwanted tramp elements, sta-bilise non-metallic inclusions segregated inthe melt, and prevent radiant heat loss fromthe molten metal. Slags having specialproperties are indispensable within specificprocess steps. However, any such slag en-trained to the next process step will notonly delay subsequent progression but willalso result in a production cost increase.

The SMS Demag slag retaining system em-ploys specially developed floating plugs aswell as ultrasonic and/or laser-based mea-suring methods. These floating plugs delaythe formation of the outlet whirl and auto-matically close the taphole.

The equipment serving to insert the floatingplug is arranged on the converter floor nearthe vessel, either mobile, suspended, orslewable, depending on the space situation.

Slag retaining device, suspended type, mobile type and slewable type.

Slag retaining device, inserting the floating plug.


24

CONVERTER RELINING

EQUIPMENT

SMS Demag offers different convertervessel relining systems. Either a platformis lowered down into the vessel by meansof rope winches in the case of integralbottom converters or, in replaceable bottom vessels, the working platform is introduced from below by means of hydraulic jacking cylinders and/or a spin-dle drive.

The relining bricks are lifted by means of a hoisting cage in the middle of thedevice. Robots serving to facilitate vessel rebricking are being developed.

VESSEL BOTTOM JACKING

DEVICE

The removable bottoms of change-bottomconverters are lined with bottom brickson a separate stand off the converter.

Changing of the vessel bottoms, meas-uring up to 4 m in diameter and weighingup to 60 t, depending on the convertersize, is fast and easy to perform by meansof a hydraulic bottom jacking device.

RELINING EQUIPMENTRELINING EQUIPMENT

Replaceable bottom andchanging device diagram. �

Diagram of relining equipment with robot.

�

25

Converter being relined with the use of araising and lowering rebricking platformwith four-rope suspension (two rope drums).

Diagram I: Relining equipment, work-ing platform raised andlowered from above.

Jacking the bottom of an 80 -t LD change vessel converter.

Diagram II: Relining equipment, working platform raisedand lowered frombelow.

Bottom jacking devices.

Relining equipmentwith spindle drive.


26

DUST COLLECTION, GASCLEANING and RECOVERYDUST COLLECTION, GASCLEANING and RECOVERY

Oxygen steel production is accompanied by considerable dust emission.

Optimised adaptation and design of the dust collecting and cleaning equipmentand possibly the use of a gas recoverysystem allow optimum operation of theoxygen steelmaking plant.

In this case also, SMS Demag offers avariety of methods and equipment tomeet this requirement.

High-performance venturi scrubbers ordry electrostatic precipitators accordingto the LT (Lurgi-Thyssen) process areavailable for the treatment of primary/process gases.

The secondary gases can be treatedeither with fabric filters or electrostaticprecipitators.

Both the Demag-Baumco system andthe LT process for gas cleaning and re-covery are capable of recovering much ofthe energy contained as carbon in themelt in the form of carbon monoxide(CO) gas during the converter process.

The recovery of the gas and the selectiveutilisation of the CO gas depreciate theinvestments required for the entire sys-tem within a very short time.

NV pH

M

V

V

Δp

NV

R

R

NV

M

T

1

2

3

Δp

T

T

P

M

VV

M M

M

T

5

7

4

6

T

Process sequence diagram:CO system� LD converter� Cooling stack with

adjustable skirt� Water-cooled hood system� Venturi scrubber tower� Fan Clean gas stack with flare Transfer station� Gasometer

27

NV

P

T8


28

ERECTION ANDCOMMISSIONINGERECTION ANDCOMMISSIONING

The range of supplies and services whichwe offer is complemented by the erec-tion and commissioning of individualsteel mill modules up to and including in-tegrated turnkey plants.

Our planning offer refers both to pre-liminary assembly and to the completeerection work and allows for country-spe-cific infrastructures, local manufacturingfacilities, and the availability of qualifiederection personnel.

Erection inspectors and chief erectorswith international experience can bemade available for supervision and forensuring qualitatively perfect perfor-mance within agreed time scales.

Our metallurgists supply technical know-how of worldwide reputation during thecommissioning of the equipment.

Erection of MRP-L converter with secondary dust collection and lance equipment.

Preassembly of a 300-t converter. Transport of a completely

preassembled 300-t converter.

29

MRP-L converter with partially installedenclosure and ladle transfer car under the converter floor.


30

SMS DEMAG CONVERTER EQUIPMENTSMS DEMAG CONVERTER EQUIPMENT

Dust collection, gas cleaningand gas recovery systems.

Bottom stirring systems.

Sublance systems.

Oxygen blowinglance systems.

31

Converters.

Change-vessel converter systems.

Slag retaining devices.

Bottom jacking and converterrelining equipment.

SMS DEMAG AG

Steelmaking and Continuous Casting Technology Division

Eduard-Schloemann-Strasse 440237 Düsseldorf, Germany

P.O. Box 23 02 2940088 Düsseldorf, Germany

Phone: +49 (0) 211 881-4316Telefax: +49 (0) 211 881-4841

E-mail: [email protected]: www.sms-demag.com

MEETING your EXPECTATIONS

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FUTURE-ORIENTED OXYGEN STEEL PRODUCTION · CONTENT 23Future-oriented oxygen steel production...

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