System combines the advantages of 100% scrap preheating and continuous scrap feeding through its chambers, without the need of EAF roof opening. EPC prevents totaly, any dust emission and heat loss during furnace charging stage, as it is the case normally for other operations. The EPC-EAF is a new generation, economical and environmentaly friendly Electric Arc Furnace. Considerable reduction in electric energy consumption, increased productivity, meeting strict environmental regulations, less dust load within the melt shop, flicker reduction& harmonic disturbance reduction are some of the important features of the new and superior EPC system.

1. NEW GENERATION IN PRE‐HEATING TECHNOLOGY
FOR ELECTRIC STEEL MAKING
HIGHER PRODUCTIVITY WITH REDUCED POWER
Knut RUMMLER ‐ KR Tec GmbH – Managing Director
Akif TUNABOYLU ‐ CVS TECHNOLOGY ‐ Technical Coordinator
Dogan ERTAS ‐ CVS TECHNOLOGY –Chief, Project and Contracting Department
In the steelmaking process, by Early scrap preheaters used
scrap melting through Electric Arc 1. INTRODUCTION independent heat sources. The
Furnace route , substantial Today's steelmakers are seeking for scrap was usually heated in the
reduction in electric power clever solutions to achive more scrap bucket. Energy savings
consumption and associated economical, ecological and flexible reported from this type of
increase in furnace productivity operations. These should be realized preheating were, as high as, 30
can be realized with Scrap Pre‐ with less maintenance intensive kWh/ton with associated
heating Technique which pre‐ equipments. These are the main reductions in electrode and
heats the scrap to about 700 °C objectives for maintaining commercial refractory consumption due to
by making use of the sensible success and competitiveness within this reduced tap-to-tap times.
heat carried in the furnace off sector. Continuing increase in electric
gas. In this respect, CVS energy costs, strict rules impossed on As EAF fourth hole offgas systems
Technology has a co operation atmospheric CO2 emissions and ever were developed, attempts were
with KR Tec GmbH, which tighter environmental regulations for made to use the EAF offgas for
developed an ‘’environmentaly land and waters lead the steelmakers to scrap preheating. A side benefit
friendly’’ and ‘’high efficiency’’ decrease their energy consumptions and reported was that the amount of
scrap preheating system to be to recycle the waste materials and baghouse dust decreased because
‘’superior’’ over the existed medias. Scrap preheating has been used the dust was sticking to the scrap
systems developed so far. This for over 30 years to offset electrical steel during preheating. Scrap
challenge led to the raise of a melting requirements. It normaly preheating with furnace offgas is
new and superior ‘’ Environmetal involves the use of EAF hot off gas to difficult to control due to the
Pre‐heating and Continuous heat scrap in the bucket, prior to its variation in offgas temperature
Charging (EPC) System’’. The EPC charging into furnace. The source of the throughout the heat cycle. In
System combines the advantages hot gas can be either solely the off gas addition, a temperature gradient
of 100% scrap preheating and from EAF and/or gas from suplementary forms within the scrap being
continuous scrap feeding through burner(s). The primary energy preheated. Temperatures must be
its chambers, without the need of requirement for the EAF is for heating controlled to prevent damage to
EAF roof opening. EPC prevents the charged scrap to its melting point. the scrap bucket and in order to
totaly, any dust emission and Thus, energy can be saved, if scrap is prevent burning or sticking of fine
heat loss during furnace charging charged to the furnace hot. Preheating scrap within the bucket.
stage, as it is the case normally of scrap also eliminates the possibility of Scrap temperatures can reach
for other operations. charging wet scrap into EAF and this 315–450°C, (600–850°F), though;
eliminates the possibility of an explosion this will only occur at the hot end
in the furnace, in case wet scrap deeps where the offgas first enters the
in liquid steel . Hence, preheating scrap preheater. Savings are typically
also improves plant safety and accidental only in the neighborhood of 18–
equipment damage. Scrap preheating 23 kWh/ton. In addition, as
reduces EAF electrical energy operations become more efficient
consumption and increases melt shop and tap-to-tap times are
productivity. decreased, scrap preheating

2. operations become more and more excessive water cooling heat
difficult to maintain. Eventualy, scrap losses from the furnace.
handling operations actually started
- HIGHER PRODUCTIVITY: Due
producing reduced productivity and
to shorter power-on and
increased maintenance costs.
power-off times. The
Some of the benefits attributed to scrap productivity of the furnace
preheating are increased productivity by can be increased by 20 %
10–20%, reduced electrical compared to the conventional
consumption, removal of moisture from EAF.
the scrap, and reduced electrode and - LONGER EAF ROOF & ROOF
refractory consumption per unit DELTA LIVES: Due to, there is
production. Some drawbacks to scrap no need for opening/closing
preheating are that hazardous volatiles the furnace roof for charging
are evolved from the scrap, creating and electric arc is always
odors and necessitating a post- away from the roof, less arc
combustion chamber downstream. damage results at roof WCP
and the minimized thermal
In addition spray quenching following shock additionally helps in
post-combustion is required to prevent extending roof delta life.
recombination of dioxins and furans. - HIGHER RETURN ON
Depending on the preheat temperature, INVESTMENT: The EPC
buckets may have to be refractory lined. System features lower
conversion cost due to the
2. DESCRIPTION OF EPC SYSTEM preheating effect.
Environmental Pre-heating and Furthermore higher
Continuous Charging has many productivity because of less
adventageous : power-on and power-off times
are assured. Depending on
- MINIMUM DUST EMMISION: During the scrap quality, some yield
charging procedure the system is gain can also be expected.
always in a closed and airtight - LESS FLICKER: Related to
situation which results in minimum the flat bath operation,
pollution level in the meltshop preheated scrap and the
- ENERGY SAVING: The EPC reduces constant energy input, a
the electric energy consumption by reduced flicker and harmonics
approx. 100 kWh/t compared to the level is reached. This also
conventional EAF. leads to less arc noise
- INDEPENDENT SCRAP CHARGING: generation.
Charging of the scrap basket is done - SAVINGS FOR SCRAP
with power-on and independently TREATMENT: The above
from the furnace operation. This saving does not take into
improves the operation and reduces consideration the additional
the power off time. Eliminating the saving of approx. 10.00 EUR /
need for EAF roof opening t liquid, due to the fact the
substantially reduces the heat loss EPC - System does not
from furnace. require any special scrap
‐ LOW DOWNTIMES / MAINTENANCE treatment.
& LESS HEAT LOSS FROM WCC: No
critical water cooled mechanical
parts such as fingers, no need for
conveyors and no extra water cooled
parts requirements which may cause
unforeseen stoppages, need
intensive maintenance, and lead to

3. The new and superior EPC design The Charging with scrap bucket is only The scrap basket will be
considers the most flexible done, for one time, and at the beginning charged into the drawer of
operational activities. the first heat of an operations cycle or in EPC while it is positioned
case of an emergency situation. inside waiting deck.
The main features are: During charging, and when the
Emission from steel making process is
one of the biggest problems. Emission charging drawer is positioned
- Flat bath operation. inside waiting deck, front wall of
- Controlled scrap charging control regulations are worldwide getting the drawer closes and isolates the
rate through telescopic feeder tighter. In the EAF field, in a sense, preheating chamber and hence
system. power saving and scrap preheating are
synonym. Various technologies have the melting process in EAF and
- Continuous charging during the preheating don’t have to be
been developed to effectively preheat
power on. interrupted.
the scrap by the furnace exhaust gas.
- Scrap charging rate is tuned
One of the issues of the EPC System is After filling the drawer by the
according to melting
to charge the scrap independent of the raised scrap basket, the slide
power/preheating
electric arc furnace melting by taking gate on top of the EPC system is
temperature.
into consideration the environmental closed.
- Uniform and well controlled aspects. The preheating chamber of EPC
bath temperature. EPC, currently developed, is a
is installed beside the EAF upper shell shaft type- preheat furnace,
- Well controlled preheating and the preheated scrap resides in this
temperature. based on AC technology. The
charged continuously, by the telescopic furnace will maintain a large hot
- Minimized off gas volume feeder system, into EAF for melting. This
heel ,(nearly 40 %), so that
related to airtight system. is while the furnace power is on. Even uniform operating conditions can
- Environmental benefits : during charging of the scrap basket into be maintained. Steel is tapped out
- Charging with closed system, the drawer positioned in the waiting
periodically via a bottom taphole
into a separate compartment deck , the preheating chamber is closed
in the furnace.
(EAF roof is closed, dedusting with the drawer’s front wall and hence
The scrap charging system
primary line is on) the furnace and preheating chambers
- Minimum fume emission are totaly isolated. This ensures little or consists of two main components,
the preheat chamber and the
during scrap charging no dust escape during furnace charging.
charging deck inside which a
- Cleaner and safer working The scrap basket will be charged into the
drawer operates.
area drawer of EPC by opening top slide gate
- 30% less off gas and while the charging drawer is The scrap is fed into the upper
- 30 % less dust at the filter positioned in the waiting deck. After part of the chamber from a
- Reduced arc noise level, charging, top horizontal slide gate is receiving hopper. The exhaust
(melting preheated scrap, closed and the charged scrap inside gas from the furnace flows up
melting flat bath conditions drawer is in waiting position. Due to through the chamber, preheating
under foamy slag) melting and preheating chambers are the scrap. Scrap preheat
- Direct preheating, charged isolated during charging EPC, melting temperatures as high as 800°C
can be achieved. Gas exit
scrap is exposed to very high and preheating don’t have to be
interrupted. Then, the drawer is temperatures from the chamber is
temperatures
around 200°C. At the base of the
- EPC respects to most forwarded by two hydraulic cylinders
towards over the preheating chamber, preheat chamber, there are two
environmental standards.
horizontally, and the scrap falls screw type pushers. These
smoothly into the preheating chamber operate in two stages, allowing
where it gets preheated. When the scrap feed into the furnace at a
drawer is over preheating zone, its rear constant rate. Offgas leaves the
wall is closing the preheating chamber. A top of the preheat chamber and
special design of the off gas duct flows to a bag filter. Some gas
together with a water cooled regulation can be recycled to the furnace to
flap allows to control the preheating regulate the inlet gas temperature
effect in the preheating chamber. to the preheater.

4. OPERATIONAL MODES OF EPC Scrap is fed continuously to the furnace All of these processes have been
1. Refining Phase of EAF until the desired bath weight is achieved. able to demonstrate some
This is followed by a short refining and benefits. The key is to develop a
Preheating of 1st bucket of next
super heating period followed by tapping process that will show process
heat in pre‐heating chamber
of the heat. Power input is expected to and environmental benefits
Charging of next bucket into be almost uniform throughout the heat. without having a high degree of
charging drawer Most furnace operations are fully complexity and without affecting
automated. Charging rate of scrap into productivity. There is no perfect
the preheater chamber is fully solution that will meet the needs
automated based on the scrap height in of all steelmaking operations.
the chamber as well as temperature of Rather, steelmakers must
the gas. Furnace feeding rate is prioritize their objectives and then
interrelated to this, and to the actual match these to the attributes of
power input. Carbon and oxygen various furnace designs. It is
injections are controlled based on the important to maintain focus on
2. Preheating inside EPC
depth of foamy slag. the following criteria:
Start feeding of preheated scrap
1. CONCLUSION 1. To provide process flexibility.
after tapping
Without doubt, current trends in EAF 2. To increase productivity while
Pre‐heating chamber half empty
design indicate that high levels of both improving energy efficiency.
drawer can move to
electrical and chemical energy are likely 3. To improve the quality of the
waiting/charging position
to be employed in future furnace finished product.
3. Charging Preheating Chamber designs. The degree to which one form
4. To meet environmental
Moving of charging drawer into of energy is used over another will be
dependent on the cost and availability of requirements at a minimum cost.
pre‐heating chamber
the various energy forms in a particular With these factors in mind, the
Preheating of 2nd bucket of next
location. There are many new processes following conclusions are drawn:
heat in pre‐heating chamber
for steelmaking which are now being 1. The correct furnace selection
Off gas flap closed commercialized. In almost all cases the will be one that meets the specific
goal is to minimize the electrical energy requirements of the individual
input and to maximize the energy facility. Factors entering into the
efficiency in the process. Thus, several decision will likely include
technologies have attempted to availability of raw materials,
maximize the use of chemical energy availability and cost of energy
into the process. These processes are sources, desired product mix,
highly dependent on achieving level of post furnace
4. Preheating inside EPC pseudoequilibrium where oxygen has treatment/refining available,
completely reacted with fuel components capital cost and availability of a
Scrap bucket in waiting position (carbon, CO, natural gas, etc.) to give trained workforce.
Continuous feeding of scrap the maximum achievable energy input to
2. Various forms of energy input
during power on the process. Other processes have
should be balanced in order to
attempted to maximize the use of the
give the operation the maximum
energy that is input to the furnace by
amount of flexibility. This will help
recovering energy in the offgases (Fuchs
to minimize energy costs in the
shaft furnace, Consteel, EOF, IHI Shaft).
long run, i.e. the capability of
These processes are highly dependent
running with high electrical input
on good heat transfer from the offgas to
and low oxygen or the converse.
the scrap. This requires that the scrap
and the offgas contact each other in an 3. Energy input into the furnace
5. Charging to Upper Hopper EPC optimal way. needs to be well distributed in
Start feeding of preheated scrap order to minimize total energy
requirements. Good mixing of the
Opening of sliding gate on top
bath will help to achieve this goal.
Charging of next bucket into
4. Oxygen injection should be
charging hopper
distributed evenly throughout the
tap-to-tap cycle in order to

5. minimize fluctuations in offgas 9. Operating practices will
temperature and composition. Thus, continue to evolve and will not
postcombustion operations can be only seek to optimize energy
optimized and the size of the offgas efficiency in the EAF but will seek
system can be minimized. In addition, to discover the overall optimum
fume generation will be minimized and for the whole steelmaking facility.
slag/bath approach to equilibrium will be Universally, the most important
greater. factor is to optimize operating
5. Injection of solids into the bath and costs for the entire facility and
into the slag layer should be distributed not necessarily one operation in
across the bath surface in order to the overall process chain. Along
maximize the efficiency of slag foaming with added process flexibility
operations. This will also enable the slag comes greater process
and bath to move closer to equilibrium. complexity. This in turn will
This in turn will help to minimize flux require greater process
requirements and will improve the understanding so that the process
quality of the steel. may be better controlled. Much
more thought consequently must
6. The melting vessel should be closed
enter into the selection of electric
up as much as possible in order to
furnace designs and it can be
minimize the amount of air infiltration.
expected that many new designs
This will minimize the volume of offgas
will result in the years ahead. As
exiting the furnace leading to smaller
long as there is electric furnace
fume system requirements.
steelmaking, the optimal design
7. Scrap preheating provides the most will always be strived for.
likely option for heat recovery from the
By the consideration of above
offgas. For processes using a high
items, CVS Technology and KR
degree of chemical energy in the
Tec companies has developed
furnace, this becomes even more
new patented solution in Pre-
important, as more energy is contained
heating technology.
in the offgas for these operations. In
order to maximize recovery of chemical
energy contained in the offgas, it will be
necessary to perform post-combustion.
Achieving high post-combustion
efficiencies throughout the heat will be
difficult. Staged post-combustion in
scrap preheat operations could optimize
heat recovery further.
8. Operations which desire maximum
flexibility at minimum cost will result in
more hybrid furnace designs. These
designs will take into account flexibility
in feed materials and will continue to
aim for high energy efficiency coupled
with high productivity. For example
operations with high solids injection, iron
carbide or DRI fines, may choose
designs which would increase the flat
bath period in order to spread out the
solids injection cycle. Alternatively, a
deeper bath may be used so that higher
injection rates can be used without risk
of blow through.