Energy Audit carried out at Heavy Forge Division, Bharat Forge Ltd., Pune as a 6-month intern.

1. FURNACE ENERGYANALYSIS
ANKUR GAIKWAD
Intern (BITS Pilani),
Heavy Forge Division-2,
Bharat Forge Ltd., Pune

2. Introduction to Bharat Forge Ltd.
• Started on 19th June, 1961 as a small hammer forge shop
• Presently, the largest forging company in the world in automobile components.
• Nine manufacturing locations in six regions like India, Germany, Sweden, Scotland
and North America and China
• Largest exporter of auto components from India
• Follows modern management practices like 5S, TQM, Six-Sigma, etc. as well as
implementing SAP for resource management

3. Introduction to Bharat Forge Ltd.
• Main Divisions in Bharat Forge Ltd., Pune:
• Forge Shop: Forging of small parts
• Die Shop: Manufacturing of dies as per requirement, for new & existing products
• CDFD (Closed Die Forge Division): R&D and Planning Division for Production using
Closed-Die Forging Route
• FMD (Forge Modernization Division): Production of Front axle beams, crankshafts using
modernized forging processes. It has 3 facilities within it: FMD-1, FMD-2, FMD-3
• HFD (Heavy Forge Division): Production of heavy forgings like shafts, defense-related
parts, etc. It has 2 facilities within it: HFD-1,HFD-2
• MCD (Machined Components Division): Machining of crankshafts, front axle beams, etc. It
has 2 facilities within it: MCD-1 (With Extension), and MCD-2
• MTB (Machine Tool-Building): Re-conditioning of old machines, Building new machines &
fixtures as required
• Heat Treatment Shop: Heat Treatment of crankshafts, and other products for enhancement of
mechanical properties
• Aero Shop: Manufacturing of Aerospace-related parts
• This presentation will focus on HFD-2, which is our area of interest.

4. Operations’Overview
• Basic materials-science-related aspects needed to
better understand process flow in HFD-2
• Forging at elevated temperatures develops residual stresses,
so stress relieving needed to prevent premature failure
• Desired microstructure obtained by processing austenite,
formed at 727oC by fan-cooling, quenching, etc.
• Tempering done to enhance toughness & impact properties
• These will help us understand the sequence of
processes in HFD-2, detailed subsequently

5. Operations’Overview
Receipt of
Required Raw
Material Ingot
Pre-heating
Ingots in
Furnaces
Forging on
4000T Press
Slow-Cooling/
Annealing
Machining
Quality
Inspection
(Ultrasonic
Tests)
Normalizing &
Hardening
(Quenching/
Fan-Cooling)
Tempering
Final Machining
Quality
Inspection
Dispatch

6. Objectives
• Energy costs are a major portion of the manufacturing costs in
the heavy forging industry, as in any other industry.
• In HFD-2, majority of the energy costs are represented by fuel
costs in operation of furnaces.
• This project is an attempt to evaluate the energy consumption of
furnaces and suggest measures to minimize the fuel
consumption in furnaces

7. Furnaces’Overview
Name of Furnace Rated
Load
(MT)
Fuel Used Operating
Temperature
(OC)
Heat Recovery
System
Function of Furnace
Forging Furnace-1
130 LPG 1230
Regenerative
Burners
Preheating ingots for hot forging
Forging Furnace-2
130 LPG 1230
Regenerative
Burners
Preheating ingots for hot forging
Forging Furnace-3
130 LPG 1230
Regenerative
Burners
Preheating ingots for hot forging
Slow-Cooling Furnace-1
95 SKO (Oil) 650 Recuperator Heating jobs to relieve internal stresses
Slow-Cooling Furnace-2
95 SKO (Oil) 650 Recuperator Heating jobs to relieve internal stresses
Normalizing Furnace-1
130 LPG 850 Recuperator Heating jobs for austenite microstructure
Normalizing Furnace-2
130 SKO (Oil) 850 Recuperator Heating jobs for austenite microstructure
Normalizing Furnace-3
95 SKO (Oil) 850 Recuperator Heating jobs for austenite microstructure
Tempering Furnace-1
95 Oil + Pilot LPG 600 NA
Heating jobs for increased toughness,
impact properties
Tempering Furnace-2
95 LPG 600 NA
Heating jobs for increased toughness,
impact properties
• A brief overview of furnaces in tabular form is presented below

8. Methodology
• Efficiency Calculation by 3 methods:
• Direct Method (Output-Input Method)
• Indirect Method (Waste-Input Method)
• SFC Method (Specific Fuel Consumption Method)
• Readings observed from-
• Oil & LPG Flowmeters: For fuel consumption in Direct Method
• PLC Display Panels: For furnace temperatures in Direct & Indirect
Method
• Production & Heat Treatment Log Books: For Load arrangement in
Direct Method
• Maintenance Log Books: For fuel consumption in SFC Method

9. Methodology
• Efficiency Calculation by Direct Method:
• η (%)= (Convection heat transfer+ Radiation heat transfer)*100
(Heat Input)
• Efficiency Calculation by Indirect Method:
• η = 100 – Waste Heat*100
Heat Input
• Efficiency Calculation by SFC (Specific Fuel Consumption)
Method:
• η = [Furnace load*Specific Heat*(Operating Temp-Ambient Temp)]*100
Fuel Consumption*Calorific Value

10. Direct Method Efficiency
Furnace Name Direct Method Efficiency (%) Load (%)
Forging Furnace-1 9.73 102
Forging Furnace-2 14.30 68
Forging Furnace-3 4.08 39
Slow-Cooling Furnace-1 0.38 62
Normalizing & Hardening Furnace-1 0.14 51
Normalizing & Hardening Furnace-2 0.10 71
Normalizing & Hardening Furnace-3 0.12 35
Tempering Furnace-1 0.00081 52
Tempering Furnace-2 0.026 37
• The results calculated by the Direct Method are tabulated below

11. Indirect Method Efficiency
Furnace Name Indirect Method Efficiency (%) Load (%)
Forging Furnace-1 93.54 102
Forging Furnace-2 91.40 68
Forging Furnace-3 97.14 39
Slow-Cooling Furnace-1 99.90 62
Normalizing & Hardening Furnace-1 91.72 51
Normalizing & Hardening Furnace-2 99.96 71
Normalizing & Hardening Furnace-3 99.87 35
• The results calculated by the Indirect Method are tabulated below
• Indirect Efficiency for Tempering furnaces not calculated because of unavailability
of flue gas thermocouples

12. Specific Fuel Consumption
Furnace Name Optimum Load (MT) SFC Efficiency (%)
Forging Furnace-1 132.6 22
Forging Furnace-2 120.9 21.5
Forging Furnace-3 135.2 24.86
Slow-Cooling Furnace-1 107.35 0.242
Slow-Cooling Furnace-2 93.1 0.076
Normalizing & Hardening Furnace-1 100.1 9.72
Normalizing & Hardening Furnace-2 135.2 0.19
Normalizing & Hardening Furnace-3 79.8 0.139
Tempering Furnace-1 79.8 0.177
Tempering Furnace-2 71.25 18
• The results calculated by the SFC (Specific Fuel Consumption) Method are
tabulated below

13. Savings due to Heat Recovery Systems
Furnace Name Heat Recovery System Savings as % of Input
Forging Furnace-1 Regenerative Burners 14.25
Forging Furnace-2 Regenerative Burners 13.88
Forging Furnace-3 Regenerative Burners 5.34
Slow-Cooling Furnace-1 Flue-Gas Recuperator 0.02
Normalizing Furnace-1 Flue-Gas Recuperator 9.21
Normalizing Furnace-2 Flue-Gas Recuperator 0.10
Normalizing Furnace-3 Flue-Gas Recuperator 0.05
• The savings due to heat recovery systems installed on each furnaces have been
tabulated below

14. Overall Results
Furnace Name DM η (%) IM η (%) SFC η (%) Load @ Min. SFC (MT)
Forging Furnace-1 9.73 93.54 22 132.6
Forging Furnace-2 14.30 91.40 21.5 120.9
Forging Furnace-3 4.08 97.14 24.86 135.2
Slow-Cooling Furnace-1 0.38 99.90 0.242 107.35
Slow-Cooling Furnace-2 NA NA 0.076 93.1
Normalizing Furnace-1 0.14 91.72 9.72 100.1
Normalizing Furnace-2 0.10 99.96 0.19 135.2
Normalizing Furnace-3 0.12 99.87 0.139 79.8
Tempering Furnace-1 0.00081 NA 0.177 79.8
Tempering Furnace-2 0.026 NA 18 71.25
η: Efficiency; DM: Direct Method; IM: Indirect Method; SFC: Specific Fuel Consumption
• Overall Results of the calculations have been tabulated below

15. Observations & Inferences
• Related to Furnace Structure:
• Every furnace is tailor-made according to the requirements by Kalyani
Thermal Systems Ltd.
• Regenerative Burners technology on Forging furnaces save about 15%
fuel.
• Internal flue gas ducts in Slow-Cooling & Normalizing furnaces
• Related to Efficiency Calculations:
• Direct Method, based on basic concepts of heat transfer, yields negligible
efficiency values
• Indirect Method, based on waste-input ratio, yields very high values due
to presence of heat recovery systems
• SFC Method yields reasonable efficiency values, but is dependent on load
as well as batch hours processed

16. Recommendations
• Insulation of Recuperator pipes, leading the hot air from
recuperator to the burners
• Stopping the leakage of flue gases from recuperator of Slow-
Cooling furnace-1
• Loading the furnaces at load at which the SFC efficiency is
maximum, as tabulated previously (Ref. Slide 11 & 13)
• Installation of heat recovery system (e.g. recuperator) for
tempering furnaces

17. Conclusion
• Brief overview of operations in Bharat Forge Ltd., with specific
focus on HFD-2 given
• Vital role of furnaces explained
• Efficiency evaluation of furnaces demonstrated
• Measures to minimize fuel consumption suggested

18. References
1.ASM Handbook Volume 4-Heat Treating
2.Materials Science & Engineering, William.D.Callister, John
Wiley & Sons Publications
3.Production Log Books in Press Cabin
4.Heat Treatment Log Books in Heat Treatment Cabin
5.Heat & Mass Transfer Databook, New Age Publications by
Kothandaraman et al
6.http://fluegasknowhow.com/
7.http://www.pipeflowcalculations.com/
8.http://www.eng-tips.com/