big succes in turnkey project_rev01

8/9/2019 Big Succes in Turnkey Project_rev01

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CVS MAKINA N. SAN. ve TC. LTD. T.

Dilovas Organize Sanayii Blgesi 3. Ksm Muallimky Cad. No:21 Gebze 41400 KOCAEL / TURKEY

Tel. +90 262 759 15 05 Fax. +90 262 759 18 80 www.cvs.com.tr [email protected]

STEELMAKING AND CASTING AT THE NEW MINIMILL

BIG SUCCESS IN TURNKEY PROJECT - HONOUR OF CVS MAKINA

D. ERTAS Project and Contracting Department CVS Makina

Located in the Turkey, near to sea port, the new minimill complex is designed to produce 1,40 million

ton/year of square billets and hot rolled coils. Design, manufacture, erection and commissioning of

steelmaking and billet caster is performed by a Turkish engineering/manufacturing company, CVS.

Produced billets are rolled in Plants existing section mill with daily production of approximatelly

1.500 ton/day. Following paper will explain the features of meltshop units designed and

manufactured by CVS MAKINA.

Introduction

Today, investors worldwide are looking and waiting for new signals from steel market to understand

where to direct and dedicate their money, energy and resources for possible alternative business.Because of uncertainty in the market, steelmakers are looking for more flexible operation to catch

the changing market demands.

In the beginning of 2008, Customer decided to invest new steelmaking plant with slab caster and hot

rolled coils. In 18.01.2008, they awarded the Turkish engineering and contracting company of CVS as

sole supplier the order for new minimill to be installed in new area, near to sea port. The Project of

steelmaking facilities was considered to be on turnkey basis. They also signed contract for slab caster

and hot Rolling mill for slab with a third party manufacturer. Because of 4 months differences

between two projects, company gave an order to CVS in 04.07.2008 such that in 12-months the

design, manufacture and erection of 6 strand 9 meter Radius Continuous Casting Machine shall befinalised.

Thanks to the good co-operation and organisation between CVSs and companys team, start-up of

new minimill and caster was performed in 13.07.2009 succesfully.

This is one of the most modern, competitive and flexible minimills for the production of billets and

HRC. The meltshop composes an 130 ton AC-EAF and a Ladle Furnace as secondary metallurgy

station and one CCM to produce square billets. The complex is designed to guarantee a productivity

of 1,4 Miotpy of commercial quality, low carbon steel, medium carbon steel and low alloy steel.

Future installation of Vacuum Degasser and adaptation of stopper rod system to CCM are alsoconsidered.

The mission of the company is not only to create big plant to serve the international market but also

to keep the environment clean around of the plant.

The CVS supply is not only meltshop equipment but also civil and steel structures of slab caster, fume

treatment plant, Materials Handling System, SVC system, Cranes for meltshop and scrap yard,

laboratuary, administrative buildings and fire detection and prevention system. All units are

connected by a special design Level 1,5 system easily adaptable to Level 2 automation system.


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Plant Concept

The plant is designed according to the latest technology in the field of steel plant machinery and

equipment.

The layout takes full advantage of the rationality of material handling in the plant in order to obtainthe following results:

- Minimum amount of areas occupied

- Optimization of personnel required

- Optimization of production time and costs.

- Best scrap handling

- Future Extension consideration of plant

The choice of the various systems making up the plant is strictly related to the achievement of the

following high-priority objectives, namely:

- Limited investment costs

- High quality products

- High productivity

- Maximum simplicity of operation

- Operation reliability

- Maximum flexibility to meet various market demands.

The technological solutions were selected with the objectives in mind to use most innovative systems

and achieve highest quality levels by a compact plant configuration. To achieve the required

production rate of 150 ton/h, furnace tap-to-tap time has to be shortened 52 minutes. With this in

mind, the single heavy bay lay-out was chosen. As a matter of fact, this configuration allows an easy

and smooth process route of liquid steel tapped from EAF, through the in-line ladle furnace refining

station to the billet caster.


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The scrap yard is considered as fully automated systems with pre-defined scrap recipies. Scrap cars

and cranes are considered as remote controlled. Crane operators can easily co-ordinate scrap car

movements by watching screens in contol pulpit.

To respect the idea of minimum areas occupied for investment, two closed scrap bay,totally 11.200

m2 area, is designed for 55.000 ton scrap storage capacity thanking to intelligent volume increase by5 meter deep than ground level. With the same design, distribution of scrap blends and truck

unloading are very easy.

Fume Treatment Plant

The FTP is designed to collect, suck and treat the primary and secondary emissions generated by the

EAF during melting, tapping and charging conditions, the primary emission generated by the LF

during heating/refining operation and the emissions generated by the Material Handling System. The

dedusting plant consists of a set of fume collection points, a set of ducting lines (water-cooled or

radiant type), a bag filter of pulse-jet and negative pressure type, a set of exhausting main fans, abooster fan for LF line and for additive suction line and a final stack for discharging the cleaned

emissions into the atmosphere. Besides, a dedicated handling and storage system is foreseen to

collect the dust generated in the bag filter and to transfer them into a storage in an appropriate area.

Main design values for fume treatment plant is designed as follows:

Suction PointFume Suction

Capacity

Maximum

Temperature

EAF Primary Emission (melting) 250.000 Nm3/h 1.200 C

EAF Secondary Emission (Charging) 1.450.000 Nm3/h 80 C

EAF Secondary Emission (Melting) 680.000 Nm3/h 50 C

Ladle Furnace 80.000 Nm3/h 150 C

Material Handling System 50.000 Nm3/h 50 C

This huge flowrate calls for pulse ject filter which are suction-type filters, equipped with compressed

air automatic bag cleaning system. The filter itself is composed of 2 parallel lines, made up of several

compartments containing a fixed number of bags.

The filter casing is made of welded steel structures with external reinforced walls. It is subdivided

into parallel compartments in such a way that each compartment can be separated from the gas

stream during cleaning cycle (off line cleaning design).

Each compartment consists of a raw gas chamber below and a clean gas chamber above divided

by the bag supporting plate. The lower chamber composes the filter body, contains the filtering bags

and the dust collecting hoppers. The upper chamber contains the injectors for the compressed air

distribution to the bags for cleaning purpose.

The two chambers are connected to the central collector respectively to the gas inlet and outlet by

means of separation dampers. Dampers for lower chambers are manually actuated, being utilized in

closed position as an additional safety in the event of maintenance or inspection; the dampers of the


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upper chambers, instead, are provided with pneumatic actuators, being automatically closed while

performing maintenance and bag cleaning in OFF-LINE mode.

The filter is completed with the supporting structures, made of steel profiles, the filter roofing and

the dust conveying system, which continuously remove the dust collected at the filter hoppers.

The normal maintenance operation of the filter does not imply to enter into the dirty section, since

all the necessary operations can be performed from above the filter head in the clean chamber. This

guarantees better working conditions for the personnel, while a manhole is foreseen in each hopper

only for inspection purposes.

The cleaning system of the filtering bags is located inside the clean gas chamber. It is composed of

one distributor per row of bags, completed with compressed air feeder to each bag.

There are 2x11 distributors (shooting pipes) per compartment, each shooting pipe having 12 nozzles

and blowing in 12 bags. The air blown by each nozzle is amplified by a Venturi, thus causing an air

pulse to flow through the filter bag (inside to outside). This pulse shakes the bag and dislodges the

dust accumulated on the external surface of the bag allowing the dust to fall to the bottom of the

filter into the collecting hopper.

The OFF-LINE cleaning cycle allows to reach high efficiency cleaning, because, as the compartment is

excluded, there is no upward gas velocity, thus allowing the dust to fall into the hopper without

being drawn again to the surface of bags. This technology allows to reach high efficiency cleaning

with a little air consumption. The small amount of compressed air utilized for bags cleaning does not

effect the overall flow rate treated by the filter.

The cleaning cycle is automatically controlled via PLC, where either a differential pressure controlledcycle or a time dependent cycle can be chosen.

Bag fitler is designed for 1.060.000 Nm3/h suction capacity at 105 C during melting and 1.580.000

Nm3/h capacity at 80 C during charging/tapping. To respect the guaranteed dust content of 20

mg/Nm3 at the stack, net filtering surface of 20.430 m2 is obtained by 24 compartments.

The pneumatic conveyors discharges the dust into the storage bin. The storage bin is cylindrically

shaped and is designed in order to facilitate the internal flow of dust and to prevent internal dust

bridge formation. Extraction of dust from the bin is performed by means of a vibrating extractor

below the lower cone of the bin itself. A manually operated emergency discharge vane is located atthe centre tip of the silo hopper. Dust silo is equipped with two dust level indicators (ON-OFF

switch) connected to the automation system that stops the operation of the dust conveying system

whenever the silo is full.

The dust separated by the filter is collected in the hoppers below and then removed via a pneumatic

conveying system. The conveying system by booster fan collect the dust from the respective hoppers

and transfer it to the storage silo.


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The pelletizing machine transforms the dust collected by the bag filter into nodules through the

addition of a binder (water), which is sprayed in a rotary plate. The pellet forms owing to their rolling

on the raking plate of the pelletizing machine, which is put in slow rotation. Thanks to the raking

position of the plate and to the material moving, the greater parts get to the surface while the

smaller parts pass to the lower beds. As soon as the plate is full of pellets (already formed), these

pass over its rim and reach the discharge chute. The system includes also a hopper to be located

underneath the pelletizing machine and designed to receive and store the pellets; the hopper is

fitted with sliding door for pellet discharge on trucks; the sliding door is driven by a hydraulic

mechanism fed by a dedicated power pack.

Operation of complete dedusting system is syncronised by automation system. Distribution of flow

to primary and secondary section of EAF is controlled by two dampers located on the lines actuated

automatically by automation. Damper position and main fan speeds according to 5 main modes of

furnace operation can be changed by HMI in FTP control room. Additionally, fan speed is adjusted

during melting phase according to the value coming from pressure transmitter measuring the

pressure inside combustion chamber.

Electric Arc Furnace

EAF is designed for nominal 130 tapping weight with 150 ton/hour Production capacity. Features of

the furnace is given in the following table:

Type of Furnace AC-ful platform

W.C. Panels Diameter 7.200 mm

Diameter of inner bottom shell 7.400 mm

Tapped Steel 130 ton

Hot heel 20 ton

Total Volume of EAF Min. 155 m3

Volume of scrap bucket 140 m3

Type of Tapping EBT

Electrode Arms Cu-conductive

Electrode Diameter 610 mm


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The EAF is designed as an AC furnace fed by a single transformer power of 130 MVA as rated power,

with an allowable overload of 20 %. Thanks to the EAF transformer tap changer, it is possible to work

with high flexibility and select to work with high flexibility and select the proper working point

according to required process phase.

The medium voltage bus-bar is equipped with totally 200 MVar Static Var Compensator (SVC) system

to handle power factor compensation and harmonic filtering. SVC reduces the disturbances on thedirty bus-bar caused by EAF and LF down to minimum value for voltage fluctiation, voltage

harmonics, power factor and flicker. SVC is composed of harmonic fitler circuits tuned to 100 Hz, 150

Hz, 200 Hz and thyristor controlled reactor (TCR). Each harmonic fitler is composed of 3 reactors, 3

condensator banks and 3 damping resistors. TCR is composed of 6 main reactors, 1 thyristor tower

and thyristor cooling unit.

The main feature of the EAF is its extremely high available power. Considering the nominal tapped

weight of 130 ton, specific available power of the furnace is 1,2 MVA/t, which is much higher than

the Standard values used for EAF design.

Furnace is charged in 2 bucket sequence with 100 % scrap practice. Furnace roof is considered with

5th hole for lime and/or dololime feeding by fully automated by MHS and 6th hole for future

consideration of continuous feding of DRI and/or HBI up to 30 %. The requirement for higher

productivity while charging significant amounts of scrap blends is maintained by four scrap cranes

equipped with 6 m3 grabs and 5 ton magnets.

Electrode movements of EAF are controlled by EARS electrode regulation system which allows a

constant ratio between electrode voltage and current to be maintained. Together with the hydraulic

system of electrode movement control, system acts on arc voltage to maximise the efficiency of

melting process. Using special algorithm following benefits can be obtained:

- Fast adjustment of arc length,

- Fast response and fast and stable control,

- Minimizing of power consumption,

- Minimizing of flicker effects due to regulation quality,

- Minimizing of electrode and refractory consumption.

EAF also employs supplementary chemical energy to save electrical power and thereby reduces

conversion cost through improved EAF productivity. Chemical energy is supplied through special


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design CVS-Combined burner system providing carbon and oxygen injection. (4+1)x6 MW burners

having each 2.500 Nm3/h average oxygen flow are installed around the furnace mounted on shell

panels. Burners are distributed for the aim to cancel cold spot areas and also to obtain good foamy

slag. In other words, the configuration was selected in order to have an as homogenous as possible

supply of chemical energy to the bath. The module philosophy follows the target of efficient

management of electrical and chemical energy, combining efficient dynamic control of the electric

arc with a balanced injection of oxygen and carbon in order to increase EAF productivity.

The oxygen jets supply the necessary oxygen amount for boosting the chemical reactions with both

elements in the bath and also injected and/or charged carbon. The injectors, designed as laval nozzle,

provide a highly coherent and efficient flow. Moreover, they make an important contribution to bath

stirring leading to chemical and thermal homogenisation.

The evolution in electric arc furnace technology has progresively led to the utilisation of alternative

energy contributing to the heat balance, optimising the consumption of electrical energy and

increasing productivity. A further effect of the correct adoption of this practice is the formation of a

high level of foaming slag, with all the benefits arising from the resulting arc coverage. To obtain

better slag foaming, additional slag door manipulator with two oxygen and one carbon lance is

installed which yields faster operation.

The carbon injectors provide the possibility to control the bath conditions by regulating the flowrate

and promoting slag foaming. This slag condition has many advantages in terms of furnace wall

protection, more efficient power utilisation and reduced maintenance.

Ladle Furnace

The final quality of the steel is obtained by means of a powerful ladle furnace capable of operating in

accordance with the required short tap-to-tap times. The furnace is conceived for reheating the steel

in the ladle placed on a ladle car and is designed and built according to the most modern techniques

in the field and is in particular provided with:

- Water cooled ladle roof equipped with indirect fume collecting hood to reduce steel

oxidation.

- Roof lifting mechanism, with hydraulic cylinder.

- Electrode arms with reduced electrode pitch diameter.

- Water cooled secondary circuit and water cooled flexible cables.

- Electro-hydraulic electrode regulation.

Transformer is chosen as 24 MVA for maximum heating rate of 5 /min. By considering 130 ton

nominal weight of steel, average time for ladle furnace is 30 minutes. The steel is continuously

stirred through one porous plag inserted in the bottom of ladle to assure good metal bath stirring to

homogenise steel chemically and thermally.

Continuous Casting Machine


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The caster is a 6-strand, 9-meter-radius machine with two unbending points. Generel features are

given below:

Machine type CVS-CC-6-9

Number of strands 6

Machine radius 9 m

Unbending radius 19 m

Strand distance 1.200 mm

Metallurgical length Minimum 27 meter

Casting section range

Outfit sections

130x130 to 200x200 mm

130x130, 150x150 & 160x160 mm

Ladle capacity (nominal) 130 ton

Ladle support Liftable-independent arm ladle turret

Tundish support Liftable tundish cars

Mould tube Curved 1.000 mm long

Oscillating unit Hydraulic type

Withdrawal speed range 0,6 6 m/min

Billet cutting Oxy-gas torches

Cutting length 6 to 12 m

Layout foresees that the new CCM shall be located parallel to the EAF and LF axis. The ladle turret of

the CCM is located in the melting bay and has the purpose to transfer the full ladle coming from

loading position in the melting bay to the casting position in the melting bay. In this bay the cooling

chamber, the main technological equipment of the new CCM and discharge area up to cross transfer

area are also placed, while the following bay (billet bay) is foreseen for housing the cross transfer

equipment of the CCM. The main hydraulic system and the main control desk are located in the

melting bay, as well as the maintenance areas for moulds.


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CCM is designed for the Production of structural, low-carbon and Si-killed grades. Billets up to 200

mm square can be cast from the machine whereas the outfit sections of 130, 150 and 160 mm

square billets are chosen for the start-up. The CCM is designed also to produce rectangular sections in

a future stage, such as 180x200 mm or 160x200 mm.

The cast sections, as well as the maximum casting speeds and Production rates for the six strands aregiven below:

Section mm 130x130 150x150 160x160 180x180 200x200

Operating strands Nr. 5 vs 6 5 vs 6 5 vs 6 5 vs 6 5 vs 6

Casting speed m/mins 4,1 3,1 2,7 2,1 1,7

Productivity t/h 158,5 190,2 159 191 158 189,6 158 189,6 158 189,6

All the steel grades are cast in open stream, using the fast nozzle changing device for long castingsequences in order to reach very good productivity and reliability levels. The design is also suitable to

submerged casting for quality steel grades for future extension.

The continuous Casting concept is made possible by rotating ladle turret and large capacity tundish

that acts as a buffer during ladle changes. The ladle turret with independent arms is liftable design to

make ladle shroud positioning easier for the operator. Each arm on the ladle turret is also equipped

with a ladle weighing system via load-cells.

T-shaped tundish design with 35 ton nominal capacity promotes inclusion removal, assuring a stable

steel flow, increasing steel residence time and homogenization for temperature patterns between

strands. The use of pool type impact pad also helps in creating a good steel flow pattern and an even

temperature through the tundish. The temperature difference between hot nad cold spots is

designed to be less than 10C.

The flow between ladle and tundish is with an automatically controlled slide gate system. Weight

cells on cantilever type tundish car measure the weight of liquid steel in the tundish and

automatically open or close the ladle slide gate to maintain the depth of steel required.

Tundish Nozzle Changer system is used to change nozzle quicker and safer, to replace damaged

nozzle during casting resulting longer sequence casting ratio, to close strand automatically automatic


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in case of emergency condition, to adjust casting speed by changing nozzle with different nozzle

diameter.

Mould technology with long copper mould and tapered design yields for high casting speed by

increasing heat transfer equally all around the mould. Thanks to the multi-tapered design, the air gap

that is formed inside the mould is reducing. Air gap is normally formed because of in the lower partof the mould by billet shrinkage and in the upper part by the difference in heat Exchange between

the faces and corners.

Quick and safe mould changing is achieved by cartridge type mould yielding pre-assembled and self-

centering design, together with self-sealing connections for cooling water supply. Foot Roll design

underneath the mould helps to overcome bulging of semi-product.

The mould is supplied with external type Electromagnetic Stirrers (EMS) to help improve the internal

structure of the billet. This is an important tool when casting high quality steels to help in the

formation of the cast structure (equaxial zone), and to avoid deposits of non-metallic or gaseousinclusions in the sub-surface area of the solidified shell. These inclusions may lead to serious defects

during the successive processes downstream of the caster.

Co60 Radioactive source is used for Automatic Mould Level Control System. It controls the liquid

steel level in the by adjusting the speed of withdrawal and straightening unit variably for open

casting. Control system is not effected by the vibrations created by steel stream impact into the

tundish and by the vibration of the casting platform. It allows flying tundish change, fly nozzle change

without casting stop. The source and detector are located on the mould body so that the location of

detector and its cable are well protected to steel splashes, over flow. Thanks to the system having

high accuracy with quick response features, for precise control of meniscus level in the mould,surface quality problems arising especially from oscillation marks are cancelled .

The oscillating table is of heavy-duty design and is sized to support the mould housings. It is designed

to permit mould oscillation along the casting radius with adjustable stroke, frequency and negative

strip time. The real oscillating curve overlaps the ideal one with strict tolerances and is stable during

machine life in order to insure quality of the billet and a longer mould life by reducing friction

between steel and copper tube. The oscillating motion is generated by a hydraulic cylinder that takes

the stroke and form variations of the wave during the casting.

The mould oscillation system is designed to maintain surface quality, limiting oscillation marks depth

and cracks generation, to allow an adequate lubrication of the solidifying shell, to obtain good heat

transfer in mould, to get shallow oscillation mark by short stroke and high frequency values.

The secondary cooling is devided into four zones, each having its own regulation loops. The cooling

for all zones is with water by correctly balanced flowrates and pressures. Sprayer designs of this multi

zone secondary cooling system is arranged to reach the goal to avoid reheating of strand surface and

to promote the continuation of shell growth, which has very ig influence on the internal quality of

end product. Additionally, to decrease the risk of break-out and avoiding internal crack, secondary

cooling system is automatically controlled in accordance with section size and casting speed.


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Each strand of the caster is equipped with a withdrawal and straightening module to carry out

dummy-bar insertion and withdrawal of the billet. The module consists of totally five rolls, three of

them are electrically driven. A hydraulic cylinder lifts and lowers the top roll and applies the required

pressure on the dummy bar or the billet. The pressure of the rolls on the billet is adjusted highly

enough to avoid skidding on the billet surface.

The billets are cut-to-length automatically by a single torch oxycutting car according to length

measurement from encoder installed on withdrawal motor. As the billet reaches the length required,

the oxycutting car automatically clamps to the side of the billet and start to cut. Clamping action

enables the car to travel forward with the same speed of the strand. After cutting operation is

finalised, clamps are opened and car returns back to park position.

After cutting, billet is transported along the run-out roller table up to billet transfer zone and lifted by

hydraulic cylinder. After completion of one billet lifted for each strand, transfer car moves them

sideways to the walking beam cooling bed. Along this unit, billet is transported by 90 rotation for

even cooling. At the end of the bed, billets are off-loaded by magnet crane and stockpiled.

Material Handling System

Material Handling System is designed to reduce manual work and to avoid losing time-demanding

material handling and automatic operation. The main operations are the storage into bins,

extraction, weighing, transport and charging of ferroalloy, additives and fluxes into scrap bucket, into

the ladle in tapping position and to the ladle refining station. All plant functions, specifically from

storage bins up to loading to the final users, are controlled automatically. The dosage is carried out

with high accuracy to obtain maximum technical results and, at the same time, to use additives and

fluxes in the best possible way to minimize expenses. Suitable interlocks are to guarantee the right

positioning of the devices.

Automation

All meltshop is equipped with sophisticated automation system based on Local Area Network

supporting the PLC Unit, operator workstations. Each phase of the process is automatically controlled

and constantly monitored to help making the various phases of the process repeatable to guarantee

the overall production cycle.


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Through the MMIs, the operator has an immediate overview of the process. They incorporate easy-

to-read graphics and user-friendly systems for rapid access and control of all phases. Alarms and

diagnostics are displayed on the screen to enable quick corrections to be carried out when necessary.

The whole meltshop is connected by Level 1,5 automation system so that each point can be

visualised from only one computer. Level 1,5 is a computer system combined with software tools,providing the operators with user interfaces on computer screens offering visual tools to enable

access to process control parameters, acknowledging the alarm messages in alarm history,

monitoring the machine conditions , simple tasks for recipe management, data exchange among local

HMI stations and reading analysis report from spectral analysis laboratuary computer.

Thanks to open architecture of SQL database, parameters can be accessed not only by the operator

but also a higher level computer system which is called level 2. It is able to built a level 2 hardware &

software on level 1,5 substructure. The user access to level 1,5 can also be classified into several

authorization levels, such as operator access level, meltshop chief access level, etc.

Main aim in designing user interfaces is to create a virtual bridge between user and machine. User

interface pages on HMI screens are designed by using Siemens WinCC HMI software which offers

screens with rich graphical objects displaying process variables, such as temperature, pressure, flow,

animated graphics and status of machine. User screens can also be used to monitor machine

conditions for maintenance purposes, for instance, monitoring the total working hours of motors,

temperature variation graphics versus time, etc.

Conclusion

The steelmaking plant of the new minimill is basically made up of one 130 ton full-platform split-shell

AC-EAF, one 130 ton inert roof ladle furnace, one material handling system, one static var

compensation system, one fume treatment plant and other auxiliaries like cranes, laboratuaries, fire

detection and sppression systems, compressed air plant, etc. are successfully designed-

manufactured-erected by CVS MAKINA as Turnkey basis in 16 months after signing the contract. In

the same way, one 6-strand multi bending 9/19 m radius billet caster was taken into operation within

only 12-months after signature. First heat was taken in 14.07.2009 very succesfull operation thanks

to many years experience of CVS in this field and good co-operation/co-ordination between CVS and

companys team.

big succes in turnkey project_rev01

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