PREFACE - UNDP · 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

`

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

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.



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

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.



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 %.


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.


The following table describes the salient features, applications, technological advantages,


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 %.



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

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%.




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 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 %.




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 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


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

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


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


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 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


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 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


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

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


Expected benefits Savings in specific power consumption by 4 – 6%.

Reduction in CO2 emissions by 4 - 6%

Estimated payback


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

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.


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.


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)


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 %.


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

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.


Calorific value of CBM is approx. 8,500 to 9,000 kcal/kg. Furnace Efficiency improved because of use of gaseous fuel.


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)


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)


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

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.


Uniform heating of stock due to better flame controllability with gaseous fuel.

Carbon neutral fuel and hence, zero CO2 emission.


Biomass/ briquettes availability and installation of biomass gas generation unit.


INR 1.5 – 2 crores (depending upon capacity)


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)


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.


Uniform stock temperature. Higher furnace productivity. Better mixing & combustion of pulverized coal


Requirement of trained operating staff. Higher capital investment.


INR 1 – 1.5 crores (depending upon capacity)


3 - 6 months.

Expected benefits

Savings in specific fuel consumption by 20 – 25 %. Reduction in CO2 emission by 20 – 25%.


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.


Uniform stock temperature. Higher furnace productivity. Radiation losses from walls and roofs can be minimized. Higher waste heat recovery.


Requirement of trained operating staff.


INR 1 – 1.5 crores (depending upon capacity)


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



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.


The need for a re-heating furnace is eliminated, resulting in a complete heat saving due to this redundancy.


Requirement of trained operating staff. Maintenance of PLC based system.


INR 1.5- 6 crores (depending on whether CCM is installed)


6 – 8 months

Expected benefits

Savings in specific fuel consumption by 80 - 100 %. Reduction in CO2 emission by 80 - 100 %.


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

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

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.


Fuel savings. Lean gases can also be used. Low flue gas volume leading to lesser sizing of flue outlet and

chimney


Provision of oxygen cylinder bank. Cooling media for burners. Requirement of proper control mechanism to maintain needed

temperatures.


Approx. INR 3.5 crores (with oxygen plant / cylinders and one set of burners as spare)


6 – 8 months

Expected benefits

Savings in specific fuel consumption by 30 - 35 %. Reduction in CO2 emission by 30 - 35 %.


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]

Documents

PREFACE - UNDP · 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