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PREFACE
United Nations Development Programme (UNDP) in collaborat ion with
Ministry of Steel (MoS), Government of India (GoI) with funding support
from Global Environmental Facil ity (GEF) implemented a project t itled
“Removal of Barriers to Energy Effic iency Improvement in the Steel Re -
Rolling Mill Sector in India” between 2004 and 2013. The project identif ied
energy eff icient technology packages fo r reheating furnace and roll ing mil ls .
The project provided technical ass istance and f inancial incent ive to the
SRRM units to adopt energy ef fic iency measures. 34 steel rerol ling mills
have successfully adopted energy effic ient technologies and accomplish ed a
substantial savings in specif ic energy consumption and reduction in GHG
emissions. Energy savings were approximately 25% in furnace o il us ing units
and exceeded 40% in coal us ing units .
UNDP along with MoS and supported by AusAID, has launched a new project
to upscale the energy eff iciency measures in steel reroll ing and other
subsectors. The project titled “Upscal ing Energy Effic ient Production in
Small Scale Steel Industry in India” aims at
Up-scal ing Energy Effic iency intervent ions in about 300 S RRM
Piloting EE measures in other steel subsectors such as Induction
furnaces
Trialing second generation of technology packages in SRRM
This publicat ion provides description of dif ferent technology packages ,
salient features and economic benefits . Most o f these are successfully
demonstrated in the earl ier project . The aim of th is publicat ion is to
disseminate details of various technology packages among the SRRMs sector
and to help to them to suitably choose the appropriate technology to improve
their present energy consumptions and reduce associated GHG emissions. We
hope the units wil l find this publication for them to make informed choice.
S N Srinivas
Programme Analyst [Energy for Development]
United Nat ions Development Programme
No. Category EE Technology Investment
estimate Saving
potential
Implementation period
Financial incentive
Maximum per unit
1
GROUP 1A Low-end EE tech equipment
Shell in shell type recu perator for pu lverized coal f iring system
INR 3 – 15 lakhs
Savings in speci f ic fu el consu mption
by 5 - 15%.
2 – 3 months
Capital su bsidy of 20% on
installat ion of individu al equ ipment
INR 2 lakhs
Modified pu lverized coal f iring system Energy eff icient pu lverizor Installat ion of au tomation & control system (Proportional Integrated Derivative [PID] based for reheating fu rnace air-fu el rat io control system) High eff icient U-tu be cross f low type metallic recu perator (for fu rnace oi l / gas f ired reheating fu rnaces) Variable Voltage Variable Frequ ency (VVVF) drive
Savings in speci f ic power consu mption
by 2 -10%
Universal spindles & cou plings Anti frict ion roller bearings Installat ion of Y -roller table in 3-Hi mill stands of rolling mills Installat ion of t i lt ing table for 3 -Hi mill stand Energy eff icient drives for rolling mills
2
GROUP 1B Low-end EE technology package
Replacement of exist ing fu rnace with new energy eff icient fu rnace
INR 1 – 2 crores
Savings in speci f ic fu el consu mption by 20 - 35%.
4 – 8 months
Consu ltancy fees
reimbu rsement on su ccessfu l
commissioning of individu al
packages
INR 2 lakhs
Conversion of fossi l fu el to CBM based reheating fu rnace Conversion of fossi l fu el to biomass based produ cer gas reheating fu rnace Revamping / modernisation of pu lverised coal f ired re-heating fu rnace Revamping exist ing fu rnace with energy eff icient top f ired re-heating fu rnace
3
GROUP 3 High-end technology-Direct rolling
Direct rolling INR 1.5- 3
crores
Savings in speci f ic fu el consu mption by 80 -100%.
6 – 8 months
Consu ltancy fees
reimbu rsement on su ccessfu l
commissioning
INR 5 lakhs
4
GROUP 5 New generation EE technologies
Regenerative bu rners
INR 1.5 – 6 crores
Savings in speci f ic fu el consu mption by above 40%
6 – 8 months
Capital su bsidy of 20% on
installat ion of individu al equ ipment
INR 20 lakhs
Oxy-fu el combu stion system
## - EE technology packages under group 2 & 4 and addit ional technologies under group 5 are under f inalization.
1A-1 Shell in shell type recuperator for pulverized coal firing
system
Description
Recuperators are generally heat exchangers
that use the energy in hot waste flue gases to
preheat combustion air. In recuperators heat flows
steadily through the wall from the heat source (hot
flue gas) to the heat receiver (cold combustion air).
Increase in air pre-heat temperature can
significantly reduce specific fuel consumption.
Salient features, Investment & Benefits
The following table describes the salient features, application, technological advantages,
limitations and cost benefit of the above technology option:
Salient features
Waste heat recovery upto 350 0C with a flue gas temperature of
700 0C can be achieved.
Recuperator designed with optimum surface area
Inner shell is made of stainless steel to withstand high
temperature.
Application All pulverized coal fired reheating furnace, which is not
equipped with recuperator.
Technological
advantages
This type of recuperator is ideal for pulverized coal fire re-
heating furnace as conjunction due to coal deposits in the
recuperator line is avoided.
Technological
limitations
Combustion air temperature to be maintained below 400 0C for
pulverised coal as the same may get ignited.
To avoid heat losses in line, combustion air pipes should be
insulated.
Estimated investment INR 3 – 6 lakhs (depending on the furnace capacity)
Estimated
implementation
period
2 – 3 months.
Expected benefits Savings in specific fuel consumption by 10 - 15%
Reduction in CO2 emission by 10 -15 %.
Estimated payback on
investment Less than 6 months.
1A-2 Modified pulverized coal firing system
Description
The steel rerolling units to a large
extent uses coal as fuel for the reheating
furnaces. However the obsolete design of
the pulverized coal firing system leads to
incomplete combustion, thereby leading to
higher specific thermal energy consumption
and burning loss.
The modified pulverized coal system provides a solution towards eradicating un-
burnt coal particles, there by leading to lower specific fuel consumption.
Salient features, Investment & Benefits
The following table describes the salient features, application, technological advantages,
limitations and cost benefit of the above technology option:
Salient features
Separate hoppers with silo and air filter system placed above burners.
Specially designed burners allow use of hot preheated combustion air and also proper mixing of fuel and air.
Air fuel flow controlled through automatic control system.
Application All pulverized coal fired reheating furnace, which is not
equipped with recuperator.
Technological advantages
The system provides solution for using 100 % hot combustion air.
Control flow air & fuel leads to lesser fuel consumption.
Technological limitations
Preheated combustion air above 400 0C may lead to ignition of the pulverized coal.
Moisture content in coal may lead to coal deposits in hoper.
Estimated investment INR 5 – 15 lakhs (excluding recuperator)
Estimated implementation period
2 – 3 months.
Expected benefits Savings in specific fuel consumption by 10 - 15%. Reduction in CO2 emission by 10 -15 %.
Estimated payback on investment
Less than 6 months.
1A-3 Energy efficient pulverizor
Description
In order to achieve maximum
combustion efficiency (-) 200 mesh fines of coal
is recommended. The same can be achieved
through a modified and energy efficient
pulverizor design.
Salient features, Investment & Benefits
The following table describes the salient features, application, technological advantages,
limitations and cost benefit of the above technology option:
Salient features
High manganese alloy, high carbon and high chromium
hammer with approximately 2000 – 2200 gms weight.
EN31 steel machine grooved liner hardened with nitriding.
Stainless steel classifier blades.
Stainless steel fan blades
RPM of approximately 2200.
Application All pulverized coal fired reheating furnace, which is not
equipped with recuperator.
Technological
advantages
Fines of -200 mesh coal size can be achieved.
Better life of pulverizor.
Technological
limitations Maintenance of critical part to be more frequent.
Estimated investment INR 10 -15 lakhs.
Estimated
implementation
period
2 – 3 months.
Expected benefits Savings in specific fuel consumption by 5 – 10%.
Reduction in CO2 emission by 5 - 10 %.
Estimated payback on
investment 6 – 9 months.
1A-4 Installation of automation & control system (Proportional
Integrated Derivative [PID] based for reheating furnace air-fuel
ratio control system)
Description
Control systems with microprocessor based PID controllers
are used in reheating furnace for controlling and regulating air-
fuel flow which has direct impact on the specific fuel
consumption.
Salient features, Investment & Benefits
The following table describes the salient features, applications, technological advantages,
limitations and cost benefit of the above technology option:
Salient features
Control of desired temperature regimes and air-fuel ratio are
possible.
Operator interaction for maintaining temperature is minimal.
Application
All types of re-heating furnace irrespective of type of fuel.
The installation of automation & control system is to monitor
flow of combustion air & gases, temperature, air fuel ratio and
pressure.
Complete interlocking and sequential control of the furnace
with respect to the charging and discharging shall be done
through relay logic to be provided in the instrumentation
panel.
Technological
advantages
Optimum fuel flow, air flow and excess air % are maintained.
Automatic control based on operating scenario.
Human errors are minimized.
Technological
limitations
Skilled manpower requirement.
Maintenance of system and instruments are required.
Estimated investment INR 5 -10 lakhs.
Implementation
period 2 -3 months.
Expected benefits Savings in specific fuel consumption by about 5 - 10%.
Reduction in CO2 emissions by 5 – 10 %.
Estimated payback on
investment Less than 6 months.
1A-5 High efficient U-tube cross flow type metallic recuperator (for
furnace oil / gas fired reheating furnaces)
Description
Recuperators are generally heat
exchangers that use the energy in hot waste flue
gases to preheat combustion air. In recuperators
heat flows steadily through the wall from the
heat source (hot flue gas) to the heat receiver (cold combustion air). Increase in air pre-heat
temperature can significantly reduce specific fuel consumption.
Salient features, Investment & Benefits
The following table describes the salient features, applications, technological advantages,
limitations and cost benefit of the above technology option:
Salient features
Waste heat recovery as high as 80% of the flue gas temperature
can be achieved.
Recuperator designed with optimum surface area
Stainless steel tubes in 1st pass and boiler quality steel in second
pass.
Application
Any reheating furnace (with F.O /gas fired), which is not
equipped with a recuperator or existing recuperator operating
with low performance (with recuperator efficiency less than
30% or temperature at recuperator outlet less than 200 0C).
Technological
advantages
High pre-heat temperature for combustion air is achieved.
Better combustion.
Technological
limitations
When the flue temperature is high, dilution with air is
required.
With the use of high temperature recuperator, the combustion
air pipes of burner need to be insulated when air temperature
is more than 400 0C.
Estimated investment INR 5 – 20 lakhs (depending on the furnace capacity)
Implementation
Period 2 – 3 months.
Expected benefits Savings in specific fuel consumption by 5 - 10%.
Reduction in CO2 emissions by 5 – 10 %.
Estimated payback on
investment Less than 6 months.
1A-6 Variable Voltage Variable Frequency (VVVF) drive
Description
It is a type of adjustable-speed drive used in
electro-mechanical drive systems to control AC
motor speed and torque by varying motor input
frequency and voltage.
Salient features, Investment & Benefits
The following table describes the salient features, applications, technological advantages,
limitations and cost benefit of the above technology option:
Salient features Can be added to existing motors & drives.
Application
Reheating furnace blower
TMT pumps
Rolling mill auxiliary motors
Technological
advantages
Energy losses are quite high in case of electrical equipment
running at fixed speed. Thus for optimum utilisation of power,
VVVF drives are most appropriate which delivers required
output for loads of varying type.
Fast and accurate control of torque and speed of drives under
all operating conditions leading to savings in electric power
consumption.
Technological
limitations Trained operating personnel with some electrical knowledge.
Estimated investment Upto INR 5 lakhs.
Implementation
period 2 – 3 months.
Expected benefits Savings in specific power consumption by 2- 3 %.
Reduction in CO2 emissions by 2 – 3 %.
Estimated payback on
investment Less than 6 months.
1A-7 Universal spindles & couplings
Description
In rolling mills, spindles & couplings are used
for transmitting power to the rolls from mill
drives/motors.
Universal joint defines as mechanical device
that can transmit torque and rotational motion from
one shaft to another at fixed or varying angle of
intersection of shaft axes.
Salient features, Investment & Benefits
The following table describes the salient features, applications, technological advantages,
limitations and cost benefit of the above technology option:
Salient features Has high torque carrying capacity.
Easy to connect or disconnect the coupling.
Application Any rolling mill with provision of changing over from CI
wobbler.
Technological
advantages
It allows some misalignment between the two adjacent shaft
rotation axes.
Operates with negligible back lash and radial clearance to
improve productivity.
Reduced maintenance.
Technological
limitations
Inter-stand distance is constraint.
Improper design of coupling & spindle can lead to vibration and
significant transmission loss.
Estimated
investment
The cost of eight sets of universal coupling and spindle for
460 mm four stand roughing mill train will be approximately
INR 10 -15 lakhs.
Implementation
period 2 – 3 months.
Expected benefits Savings in specific power consumption by 5 – 8%.
Reduction in CO2 emissions by 5 – 10%.
Estimated payback
on investment Less than 1 year.
1A-8 Antifriction roller bearings
Description
Basic purpose of bearing in rolling mills is
to provide a frictionless support and guide a
rotating machine part.
Antifriction roller bearings are more
desirable than fibre/brass cotter bearing due to
their lower friction and reduced lubrication requirement and their coefficient of friction is
0.005.
Salient features, Investment & Benefits
The following table describes the salient features, applications, technological advantages,
limitations and cost benefit of the above technology option:
Salient features
Less friction due to facet contact.
Better tolerance of products.
Longer life and can be fitted in existing system with
modification.
Application All mill stands excluding the ones having layout/technological
constraints.
Technological
advantages
An antifriction bearing minimizes torque on spindle leading to
lower power consumption.
Higher mill speed can be achieved with respect to other
bearings.
Technological
limitations Modification in roll chock design.
Estimated
investment
Approximately INR 3 – 6 lakhs to cater to 460 mm 3 Hi roughing
mill stand.
Implementation
period 2 – 3 months.
Expected benefits
The mill utilization goes up by 5%.
Savings in specific power consumption by 3 – 5 %.
Reduction in CO2 emissions by 3- 5%.
Estimated payback
on investment Less than 1 year.
1A-9 Installation of Y-roller table in 3-Hi mill stands of rolling
mills
Description
In three-high (3-Hi) mill, three rolls rotate in one
direction and the metal is fed through two rolls and then
returned through the other pair with middle roll being
common.
Material handling in typical 3 Hi mill train is done manually. A Y-roller table is a
steel fabricated material handling system for automatic transfer of bar from one stand to
another stand.
Roller is skewed for bar to be taken up by Y roller table and feeds the bar between
top roll and middle roll of 3-Hi mill. It improves bar handling, less temperature drop for
next pass and human safety.
Salient features, Investment & Benefits
The following table describes the salient features, applications, technological advantages,
limitations and cost benefit of the above technology option:
Salient features Designed based on production handling capacity for automatic
transfer of hot bar
Application 3 Hi mill train rolling billet less than 130 mm cross section.
Technological
advantages
Elimination of temperature variation of stock
Elimination of human error
Technological
limitations Mill logistics
Estimated
investment
Y-roller table mounted at 1st stand of 480 mm roughing mill to
convey the rolling stock, size 1500 mm wide X 14800 mm long is
around INR 5 - 10 lakhs.
Implementation
period 2 – 3 months
Expected benefits
Approximate reduction of 3 -4 skilled manpower per shift.
10 % increase in mill utilization.
Savings in specific power consumption by 4 – 7 %.
Reduction in CO2 emissions by 4 – 7%.
Estimated payback
on investment Less than 1 year.
1A-10 Installation of tilting table for 3-Hi mill stand
Description
Re-rolling sector in India in general has 3-
hi mill stands in roughing mill train. The metal is
being fed to various passes manually by hooks &
tongs.
Installation of tilting table towards the
entry side and delivery side of passes between
top-roll and middle rolls ensures smooth guided
entry of metal to the passes and also eliminates the
manual lifting, feeding of the rolling stock. This installation further ensures the constant
temperatures for all the various bars.
Salient features, Investment & Benefits
The following table describes the salient features, applications, technological advantages,
limitations and cost benefit of the above technology option:
Salient features Designed based on production handling capacity for automatic
transfer of hot bar.
Application All 3 hi- rough mill stands excluding the ones with layout
constraint.
Technological
advantages
Elimination of temperature variation
Uniform feeding to passes (lesser damage to front & back ends of
the stock).
Technological
limitations Possibility of motor drive failure.
Estimated
investment
The approximate cost for the installation of tilting table for a 3-Hi
mill stand, 410 mm dia is around INR 10 -12 lakhs.
Implementation
period 2 - 3 months
Expected benefits
Higher Mill utilization by 5 -10%.
Approximately 3-4 skilled manpower is reduced per shift.
Savings in specific power consumption by 6 - 8 %.
Reduction in CO2 emissions by 6 - 8%.
Estimated payback
on investment Less than 1 year.
1A-11 Energy efficient drives for rolling
mills
Description
Energy efficient motors are most suitable option
for power intensive steel industries where auxiliary
drives like air blowers, water pumps, oil pumps, compressors etc. are continuously working
for long duration, every day.
Generally in industries, proper sizing of high capacity motors are not practiced,
which draws more power because of low loading or idling operations.
Downsizing such motors and replacing with energy efficient motors will lead to a
considerable savings in power consumptions.
Salient features, Investment & Benefits
The following table describes the salient features, applications, technological advantages,
limitations and cost benefit of the above technology option:
Salient features
High efficiency (upto 92%) – low running cost.
These motors are more tolerant of overload conditions and
phase imbalance.
Applications All rolling mill auxiliary load motors (upto 315 kW)
Technological
advantages
High quality and thinner steel laminations on starter.
Corrosion resistant.
Less noise and vibration.
Accurate machine tolerances to reduce fixed losses.
Energy efficient motors in conjunction appropriate capacitor
banks offer an ideal environment for operating the drives at
high efficiency and improved power factor.
Technological
limitations
The energy efficient motors are especially suitable for
continuously running drives working for long duration
everyday where energy cost is very high.
Estimated investment INR 8 – 10 lakhs
Implementation
period 2 – 3 months.
Expected benefits Savings in specific power consumption by 4 – 6%.
Reduction in CO2 emissions by 4 - 6%
Estimated payback
on investment Less than 1 year.
1B-1 Replacement of existing furnace with new energy efficient
furnace
Description
Energy efficient furnaces are provided
with automatic temperature, pressure control,
high efficiency metallic recuperator and
improved refractory lining.
The heating zone constitutes 70 – 75% of
the total installed heating capacity while the
soaking zone will be having the balance 30 - 25%
heat load.
Top fired pusher type furnace design
with hearth productivity ≥ 300 kg/m2/h.
Salient features, Investment & Benefits
The following table describes the salient features, applications, technological advantages,
limitations and cost benefit of the above technology option:
Salient features
Optimum design of furnace. Shorter pre-heating zone. 70% of total heat input in heating zone and 30% in soaking zone. Better combustion system & burners Optimum refractories & insulation Waste heat recovery through recuperator Automation & control system installed.
Application Across all furnace capacity & fuel types.
Technological advantages
Uniform heating of stock is achieved Optimum hearth utilization. Proper combustion. Air-fuel ration controlled with optimum sp. energy consumption. Higher efficiency of furnace achieved.
Technological limitations
Unique design based on fuel type and raw material cross-section. Higher capital cost.
Estimated investment INR 1.5 – 2 crores (for a capacity of 20 tph; Stock : Billets of 110 x 110
mm size)
Estimated implementation period
4 – 6 months.
Expected benefits
In case of furnace oil, the savings in specific fuel consumption by 20 – 25 %.
In case of pulverized coal, the savings in specific fuel consumption by 35 – 40 %.
Reduction in CO2 emission by 20 - 40 %.
Estimated payback on investment
Less than 1 year.
1B-2 Conversion of fossil fuel to CBM based reheating furnace
Description
Coal bed methane (CBM) is a form of natural gas extracted
from coal beds.
Can be utilized as a fuel for re-heating furnace.
Required design modification in furnace to be carried out
along with safety precautions.
Salient features, Investment & Benefits
The following table describes the salient features, applications, technological advantages,
limitations and cost benefit of the above technology option:
Salient features
CBM is a cleaner, safer, more environmentally friendly fuel than many other energy sources, including conventional natural gas.
Use of CBM requires certain deign modification in the furnace. Safety precautions have to be ensured. All other design features of energy efficient furnace to be
incorporated along with switch over of fuel.
Application
CBM consists of over 90% methane and this can be directly used for combustion in all types of reheating furnace.
Applicable in areas where CBM is available through pipelines.
Technological advantages
Calorific value of CBM is approx. 8,500 to 9,000 kcal/kg. Furnace Efficiency improved because of use of gaseous fuel.
Technological limitations
CBM recovery is carried out in few parts of the country and initial investment in mining, transporting CBM is very high.
Tar produced needs to be completely removed from the gas. Otherwise, it can choke valves, pipelines, burners etc.
Higher running cost of CBM.
Estimated investment
INR 1.5 – 2 crores (for a capacity of 20 tph; Stock : Billets of 110 x 110 mm size)
Estimated implementation period
4 – 6 months.
Expected benefits
In case of furnace oil the savings in specific fuel consumption (along with furnace modification) by: 20 – 25 %.
Reduction in CO2 (thermal) emission by 100 %. (net zero CO2 emission)
Estimated payback on investment
Less than 1 year.
1B-3 Conversion of fossil fuel to biomass based producer gas
reheating furnace
Description
Biomass Gasification converts solid biomass into a more
convenient gaseous form. The gas so obtained is called biomass gas,
which is combustible having a calorific value of 1050 to 1200Kcal/
Nm3, with an average composition of :-
CO : 20 ± 1%
CH4 : 3 ± 1%
H2 : 20 ± 1%
CO2 : 12 ± 1%
and rest N2. Unlike fossil fuels, biomass does not add carbon dioxide to the
atmosphere as it absorbs the same amount of carbon while growing. It is the cheapest, eco-
friendly and renewable source of energy.
Salient features, Investment & Benefits
The following table describes the salient features, applications, technological advantages,
limitations and cost benefit of the above technology option:
Salient features
Biomass gas has calorific value similar to that of producer gas which is around 1200 kcal/nm3.
Biomass briquettes can be used in existing coal based producer gas plants with certain design modifications.
Application Across all furnace capacity & fuel types subject to availability of
biomass briquettes.
Technological advantages
Uniform heating of stock due to better flame controllability with gaseous fuel.
Carbon neutral fuel and hence, zero CO2 emission.
Technological limitations
Biomass/ briquettes availability and installation of biomass gas generation unit.
Estimated investment
INR 1.5 – 2 crores (depending upon capacity)
Estimated implementation period
6 - 8 months.
Expected benefits
Savings in specific fuel consumption (along with furnace modification) by 20 – 25 %.
Reduction in CO2 (thermal) emission by 100%. (net zero CO2 emission)
Estimated payback on investment
Less than 1 year.
1B-4 Revamping / modernisation of pulverised coal fired re-heating
furnace
Description
Most of the steel re-rolling mill units in India
use pulverized coal as fuel.
However, in general, most of these reheating
furnaces are of obsolete design and are not equipped
with waste heat recovery, automatic temperature and
pressure control, and good insulation lining.
The following areas of the furnace needs to be
revamped for efficient operation
Waste heat recovery system suitable for pulverized coal firing.
Modified pulverized coal firing system to ensure use of hot gas.
Automatic control of air-fuel ration for controlled heating.
Furnace excess air & pressure control through automatic damper and online oxygen analyser.
Improved combustion system with specially designed burners.
Improved pulveriser to provide better mesh size of coal.
Improved refractory lining. Salient features, Investment & Benefits The following table describes the salient features, applications, technological advantages, limitations and cost benefit of the above technology option:
Salient features
Separate hopers with silo and air filter system placed above burners. Specially designed burners allow use of hot preheated combustion air
and also proper mixing of fuel and air. Air fuel flow controlled through automatic control system. Improved design of pulveriser installed. Improved furnace design along with optimum refractories &
insulation.
Application All pulverized coal fired reheating furnace.
Technological advantages
Uniform stock temperature. Higher furnace productivity. Better mixing & combustion of pulverized coal
Technological limitations
Requirement of trained operating staff. Higher capital investment.
Estimated investment
INR 1 – 1.5 crores (depending upon capacity)
Estimated implementation period
3 - 6 months.
Expected benefits
Savings in specific fuel consumption by 20 – 25 %. Reduction in CO2 emission by 20 – 25%.
Estimated payback on investment
Less than 1 year.
1B-5 Revamping existing furnace with energy efficient top fired
re-heating furnace
Description
In general most of the SRRM’s uses reheating
furnace which are not equipped with good waste heat
recovery system, automatic temperature and pressure
control, heat recovery system and good insulation lining.
The following areas of the furnace needs to be
revamped for efficient operation
Furnace Design
Heat Distribution pattern.
Temperature & pressure control
Automatic damper with online oxygen analyser
High efficiency metallic recuperator
Improved refractory lining Salient features, Investment & Benefits
The following table describes the salient features, applications, technological advantages, limitations and cost benefit of the above technology option:
Salient features
Controls for desired temperature, pressure & air fuel ratio. Waste heat recovery upto 500 0C with a flue gas temperature of 700 0C will
be achieved. Online oxygen analyser will indicate the excess air present in the furnace
which in turn will help in reducing scale losses. The excess air will be controlled through automatic damper.
Improved refractory lining will be provided to reduce radiation losses. Furnace design based on optimum hearth utilization (≥ 300 kg/ m2/h). Separate combustion air and fuel pipelines for different zones of furnace.
Application Re-heating furnaces of all capacities and different fuel options.
Technological advantages
Uniform stock temperature. Higher furnace productivity. Radiation losses from walls and roofs can be minimized. Higher waste heat recovery.
Technological limitations
Requirement of trained operating staff.
Estimated investment
INR 1 – 1.5 crores (depending upon capacity)
Estimated implementation period
3 - 6 months.
Expected benefits
In case of furnace oil the savings in specific fuel consumption by 20 – 25 %.
In case of pulverized coal the savings in specific fuel consumption by 30 – 35 %.
Reduction in CO2 emission by 20 - 30%. Estimated payback on investment
Less than 1 year.
3.1 Direct rolling
Description
Direct rolling process is
a technical evolution of hot
charging, where continuous
cast billet is directly pushed to
the rolling mill, without the
need of intermediate process of
reheating.
The direct rolling
process can be adopted in composite units by controlling the secondary cooling of the
continuous casting machine by means of Programmable Logic Control (PLC), hydraulic
cutting of billets, high-speed transfers of hot billets, and a canopy covering over the
conveyer belt.
Salient features, Investment & Bene fits
The following table describes the salient features, applications, technological advantages,
limitations and cost benefit of the above technology option:
Salient features
Induction furnace facility of suitable capacity installed. High temperature tapping of liquid metal practiced. Continuous casting machine (preferably with double strand casting)
installed. High temperature achieved at CCM cooling bed. Sequence casting to get required capacity of hit billets. Secondary cooling of CCM controlled. Hydraulic shear installed to reduce cutting time. High speed transfer (with canopy cover) of hot billets to rolling mill. Design modification in roll pass design to handle hot billets.
Application Direct rolling is applicable to all the composite SRRM units subject to
availability of required capacity of hot charge from continuous casting machine.
Technological advantages
The need for a re-heating furnace is eliminated, resulting in a complete heat saving due to this redundancy.
Technological limitations
Requirement of trained operating staff. Maintenance of PLC based system.
Estimated investment
INR 1.5- 6 crores (depending on whether CCM is installed)
Estimated implementation period
6 – 8 months
Expected benefits
Savings in specific fuel consumption by 80 - 100 %.
Reduction in CO2 emission by 80 - 100 %.
Estimated payback on investment
Less than 1 year.
5.1 Regenerative burners
Description
Regenerative burners use the heat of flue gases to preheat the air and gases going to
the burners thus optimising the heat input at the source itself.
Set of burners used in the entire length of the furnace.
Salient features, Investment & Benefits
The following table describes the salient features, applications, technological advantages, limitations and cost benefit of the above technology option:
Salient features
Air preheat temperatures of around 1000 0C are achievable resulting
in exceptionally high thermal efficiency.
Eliminates installation of blowers and pre-heating zone.
Application All gaseous fired reheating furnaces.
Technological
advantages
High thermal efficiency can be achieved through pebble bed regenerators or with honey comb type regenerators.
Uniform heating of the stock as almost flameless combustion takes place.
Increased production from existing facilities Reduced emissions of carbon dioxide and carbon monoxide.
Technological
limitations
Good instrumentation as pre-requisite. Unclean gas may affect valves and other change over mechanism.
Estimated
investment INR 3-6 crores (depending on the no. of burners required)
Estimated
implementation
period
6 – 8 months
Expected
benefits Savings in specific fuel consumption by 35 – 40 %. Reduction in CO2 emission by 25 - 30%.
Estimated
payback
on investment
Less than 2 years.
5.2 Oxy-fuel combustion system
Description
Oxy fuel burners’ use pure oxygen to substitute completely / part of combustion air
thus reducing the nitrogen component of
combustion air and hence, reducing sensible
heat loss by reduced volume of flue gas.
Also, lean gases can also be used with
oxy-fuel burners and still required temperatures
can be attained.
Salient features, Investment & Benefits
The following table describes the salient features, applications, technological advantages, limitations and cost benefit of the above technology option:
Salient features
The mass and volume of the flue gas are reduced by approximately 75%.
Because of the reduced flue gas volume, less heat is lost in the flue gas.
The nitrogen percentage in flue gas reduced drastically.
Application All types of re-heating furnace irrespective of type of fuel.
Technological advantages
Fuel savings. Lean gases can also be used. Low flue gas volume leading to lesser sizing of flue outlet and
chimney
Technological limitations
Provision of oxygen cylinder bank. Cooling media for burners. Requirement of proper control mechanism to maintain needed
temperatures.
Estimated investment
Approx. INR 3.5 crores (with oxygen plant / cylinders and one set of burners as spare)
Estimated implementation period
6 – 8 months
Expected benefits
Savings in specific fuel consumption by 30 - 35 %. Reduction in CO2 emission by 30 - 35 %.
Estimated payback on investment
Less than 2 years.
Reference
Study Report to Ascertain Extent of Replication of Energy Efficient Technologies in Steel
Re-rolling Mill Sector in India 2012-2013, prepared by SAIL-CON.
Data gathering report on Eco-Tech Options, updated by RDCIS-SAIL in 2011-2012.
United Nations Development Programme (UNDP) 55 Lodhi Estate
New Delhi, India. Pin Code - 110 003 Tel: 91 11 46532333. Fax: 91 11 24627612
Email: mailto:[email protected]