Indian experiences on Energye Efficiency in Steel Rolling Mills

D. Pawan KumarTeam Leader

D. Pawan KumarTeam Leader

ENERGY EFFICIENCY

SHARING INDIAN EXPERIENCES

ENERGY EFFICIENCY

SHARING INDIAN EXPERIENCES

04/12/23

Current Major EE initiatives/Drivers

04/12/23

Accelerated depreciation for EETsEnergy Conservation Act implementation, NMEEEMNRE initiatives APDRP & RAPDRP programmesMSME schemes for SME sectorCDM and other international ProgrammesSDA capacity buildingDC & PAT SchemeS&L ProgrammesSME Clutter programmeDSM (Agriculture, Municipal DSM)NECA, initiatives, BLY, ECBC SchemeISO 50001ESCO capacity buildingFinancial instruments /Bank Schemes

ENERGY CONSERVATION TECHNOLOGIESADOPTED IN INDIAN STEEL ROLLING MILLS:

• Low - end Technologies

Requires investment Rs. 1.5 to 2 Crores and energy saving 20-25%

• High-end Technologies• Requires investment Rs. 5 to 6 Crores and

energy saving 30-40%

04/12/23

Low - end Technologies

• High efficiency recuperator with improved furnace design

• Change of lump coal to producer gas as fuel• Technology for use of pulverized coal as fuel• Use of Bio-mass gas as fuel

04/12/23

High-end Technologies

• Regenerative burner system• Hot charging of continuous cast billet• Top and bottom firing system in reheating

furnace• Oxy - fuel combustion system in reheating

furnace• Walking hearth/beam furnace

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ECO TECH OPTIONS IN FURNACES

• Total replacement of the existing pusher type with the energy efficient furnace.

• Walking beam reheating furnace• Producer gas based reheating furnace• Modifying of grate coal fired system to

pulverized

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ECO TECH OPTIONS IN FURNACES Contd…

• Revamping /modernization of existing pusher furnace

• Efficient oil burners• Regenerative burners• Complete change of furnace line• Ceramic fibre veneering

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ECO TECH OPTIONS IN FURNACES Contd…

• Microprocessor based furnace zone temperature/pressure control

• Metallic Recuperator • Hot Charging in composite mills• Variable voltage variable frequency drive

(VVVF)

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ECO Tech options in Rolling Mills

• Crop length optimization• Rollers guide• Spindle and coupling• Antifriction bearing• Installation of Y-roller table• Installation of drop tilter• Installation of tilting table

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ECO Tech options in Rolling Mills Contd…

• Quenching and self-tempering of re-bars• Oval repeaters • No - Twist Block• Slit rolling• Computerized roll pass design• Lubrication technology

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ECO Tech options in Rolling Mills Contd…

• Cast in carbide rolls in conventional stands• Endless welding roll• Reactive power compensation• Energy efficient drives for rolling mills• Pre-stressed housing less stands• High voltage (HT) AC motor for rolling mills

etc

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Recommendation

Key Technical elements of proposed design

Major Specification

Standard Equipment Suppliers

Productivity/Yield Improvements, Power consumption reduction, Fuel Consumption Reduction etc.

Investment in Rs. Lakh

Reheating FurnaceProper Coal storage

House keeping measure which reduces carpet loss

Furnace Instrumentation

1.Pressure gauge,2.Thermocouple for flue gas,3.O2 Analyser for flue gas4. Automation of air and fuel ratio

+0.1mm W.G800 (max)degCElectronic gas analyser

Amsat EDC Pune Maharastra

Better operation control and efficiency improvement

2 lakhs

TECHNOLOGY PACKAGES /ECO-TECH OPTIONS & SPECIFICATION OF MAJOR FACILITIES

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Recommendation

Key Technical elements of proposed design

Major Specification

Standard Equipment Suppliers

Productivity/Yield Improvements, Power consumption reduction, Fuel Consumption Reduction etc.

Investment in Rs. Lakh

Variable Frequency drive for combustion air blower

Variable Frequency Drive (VFD)

ABB Power savings 0. 8 lakhs

Waste heat recovery by installing metallic recuperator

Metallic recuperator

Indaid Engineers (P) Ltd., Chennai

Waste heat recovery,fuel saving and efficiency improvement

7 lakhs

Energy efficient burner

Energy efficient burner

Webster Engineers & manufacturing Company

Better turbulence and excess air reduction

1.5 lakh

Contd…

04/12/23

Recommendation

Key Technical elements of proposed design

Major Specification

Standard Equipment Suppliers

Productivity/Yield Improvements, Power consumption reduction, Fuel Consumption Reduction etc.

Investment in Rs. Lakh

Rerolling MillUniversal spindle and coupling

Spindle & coupling

Armech Engineers (P) Ltd., Noida

Power savings 6 lakh

Antifriction bearing for rollers

Antifriction bearings

Powersavings

2 lakh

Installation of roller table at furnace discharge

Mill Mechanization

Delay in rolling 1.5 lakhs

Installation of tilting table and drop tilter at roughing stand, Skew table& roller table at all mill stand

Mill Mechanization

Power saving 3 lakhs

Contd…

04/12/23

Practice Parameters on which performance is measured

Productivity (tph)

Utilization (%)

Fuel (kg/t) (lt/t) (Nm3/t)

Power (kWh/t)

Burning loss %

Mill Scale (%)

Rolling and cuts (%)

Yield (%)

Current Practices

8TPH 70% 100 kg/t

97 1.57 0.50 1.4 96.53%

Projected Case

8TPH 70% 75 kg/t

85 1.5 0.50 1.4 96.60%

Benchmark 80% 65 kg/t

80 1.3 0.5 0.5 97.7%

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The energy balance sheet of unit for baseline and ecotech for Reheating furnace

Operating Parameter Base line Projected CaseFuel Consumption( per MT of throughput), kg 100 75

Scale loss,( per MT of throughput), kg 20.6 20

Through put rate ( tonnes per hour), tph 7.25 8

Furnace Parameter

Rolling Temperature, Hs(0C) 1280 1200

Avg Skin Temperature, ts 67 67

O2 in flue Gas (%) 12 7

CO2 in Flue Gas(%) 9 12.5

CO in Flue Gas ( PPM) 60 60

Excess air ( %) 133 50

Exhaust gas temp at furnace backend, Th in (0C) 518 600

Exhaust gas temp at Stack, Th out (0C) 518 250

Air Preheat Tf (0C) NA 300

Fuel Preheat ( 0C) NA NA

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Operating Parameter Base line Projected CaseThickness of Refractory lining , X (cm) 50 50Calorific value of fuel 6000 6000Energy Input ( Thermal) Fuel ( Mcal/t) 600 450Sensible heat of fuel (Mcal/t) NA NASensible heat of air ( Mcal/t) NA 67.5Heat of formation of scale ( Mcal/t) 20.9595 20Total 620.9595 537.5Energy Output (Thermal) Steel (Mcal/t) 149.52 149.52Scale (Mcal/t) ………….. Dry exhaust gas , (Mcal/t) 191.5262237 124.0262237Water vapur ( Mcal/t) 37.580366 37.580366Heat Loss due to radiation and convection(Mcal/t) 41.56015617 41.56015617Heat Loss due to opening (Mcal/t) 42.63917863 30Heat Loss due to non continous operation (Mcal/t) 48 40Total 510.8259245 422.6867459Other difference , (Mcal/t) 110.1335755 114.8132541

Contd…

04/12/23

Summary of Rolling Mill Parameter

Operating Parameter Baseline Projected CaseSpecific power consumption ( KWh/t) 97 85power Factor 0.98 0.99Mill utilization (%) 70 70Mill yield (%) 96.5 96.6Miss roll (% of furnace throuput) 1.04 1Mill scale (%) 0.49 0.49

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Summary of Rolling Mill Parameter

Operating Parameter Baseline Projected CaseRolling Mill Parameter Rolling Temperature at furnace discharge (⁰C) 1200 1150Rolling Temperature at roughing mill inlet (⁰C) 1125 1125

Rolling time (Seconds)

Roughing

Intermediate

Finishing 40 40

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Summary of Rolling Mill Parameter

Operating Parameter Baseline Projected CaseRolling Temperature at finishing mill outlet (⁰C) 850 850Rolling Temperature at cooling bed (⁰C) 850 850Mill efficiency (%)

70 70Mill delays ( Min)/day

75 50Total roll cooling water consumption (m3/s/t) Total roll consumption (kg/tonne of finished product)

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Thank you