How do the Bureau of Energy Efficiency Jamnagar oil to gas reheating furnace reports for 750, 1,200 and 2,000 kg an hour compare?

Each Bureau of Energy Efficiency (BEE) Jamnagar report swaps 37.03 litres of oil per tonne of billets for 26 normal cubic metres (Nm3) of gas. Payback falls from 1.97 years at 750 kilograms an hour to 1.56 at 1,200 and 1.15 at 2,000, because the reports assume 1,500, 2,400 and 4,000 tonnes a year.

The three reports side by side

• 750 kilograms (kg) an hour: 1,500 tonnes a year, 55,545 litres of oil replaced by 39,000 Nm3. Saving rupees (Rs) 6.03 lakh, cost Rs 11.85 lakh, payback 1.97 years, net present value (NPV) Rs 10.25 lakh, internal rate of return (IRR) 33.54%.
• 1,200 kg an hour: 2,400 tonnes, 88,872 litres, 62,400 Nm3. Saving Rs 9.74 lakh, cost Rs 15.20 lakh, payback 1.56 years, NPV Rs 20.77 lakh, IRR 45.99%.
• 2,000 kg an hour: 4,000 tonnes, 148,120 litres, 104,000 Nm3. Saving Rs 16.33 lakh, cost Rs 18.70 lakh, payback 1.15 years, NPV Rs 42.29 lakh, IRR 67.65%.
• Each is seven days of downtime and 13 weeks to install.

What does not change

• Existing furnace 18% efficient at 37.03 litres of oil a tonne, new furnace 29% at 26 Nm3 of gas a tonne.
• Oil at Rs 28 a litre is Rs 1,036.84 a tonne, gas at Rs 24 a Nm3 is Rs 624, a saving printed as Rs 412 a tonne.
• The same 2 horsepower (HP) blower, 1.492 kilowatts, is charged in all three, about 2,984 kilowatt hours (kWh) or Rs 0.15 lakh a year, whether the furnace is 750 or 2,000 kg an hour.

Where the payback gain comes from

Tonnes are the rated kg an hour times 2,000 hours (my reading of the printed sums). Saving grows with tonnes, while price grows slower: Rs 15.80 lakh for each tonne an hour of rating at 750, Rs 12.67 lakh at 1,200 and Rs 9.35 lakh at 2,000 (my arithmetic). So the biggest furnace pays back first on paper. All three were derived from one measured run, 661 kg of billets on 25 litres of oil, so a unit heating far fewer tonnes should scale the saving down by its own tonnes. The 1,200 kg report's body table prints erection at Rs 1.70 lakh while its cash-flow sheet and text print Rs 1.35 lakh; the Rs 15.20 lakh total is the same either way.

Carbon dioxide (CO2): what is printed and what to use

• Printed net cuts: 97, 154 and 253 tonnes a year, about 64 kilograms of CO2 per tonne of billets in each report.
• They count the oil at about 3.17 kg a litre (176, 281 and 470 tonnes) and the gas at 2.03, 2.04 and 2.09 kg a Nm3 (79, 127 and 217 tonnes). The 2,000 kg gas line is about 3% above the other two.
• Our other Jamnagar pages use 2.97 kg a litre for furnace oil, an estimate. On that, the 750 kg cut is about 84 tonnes, 1,200 kg about 135 and 2,000 kg about 221, after the blower at 0.675 kg a kWh.

The 750 kg furnace, report sums

• Fuel per tonne: Rs 1,036.84 oil less Rs 624 gas = Rs 412 (printed). 1,500 tonnes x Rs 412 = Rs 6.18 lakh
• Less blower power Rs 0.15 lakh gives Rs 6.03 lakh. Payback Rs 11.85 lakh / Rs 6.03 lakh = 1.97 years
• CO2 on our oil estimate: 55,545 x 2.97 = 165 tonnes, less the report's gas 79 tonnes, less 2,984 kWh x 0.675 = 2 tonnes, about 84 tonnes

Prices are the reports' own at 2010. The oil factor is our estimate; the gas figure is the report's own.

What Senseible does here

Senseible reads oil invoices, gas bills and electricity bills into monthly records, so oil or gas per tonne of billets before and after a furnace change is on file. It does not size furnaces or check a maker's efficiency claim.

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Sources: BEE, Detailed project report: energy efficient gas fired reheating furnace, 750 kg, Jamnagar brass cluster (2010, SAMEEEKSHA), BEE, Detailed project report: energy efficient gas fired reheating furnace, 1,200 kg, Jamnagar brass cluster (2010, SAMEEEKSHA), BEE, Detailed project report: energy efficient gas fired reheating furnace, 2,000 kg, Jamnagar brass cluster (2010, SAMEEEKSHA)

Last reviewed 2026-11-06. Report figures are from BEE's Small and Medium Enterprises (SME) programme project reports; costs, fuel prices and paybacks are at 2010 prices. Redo the payback with today's oil and gas prices and a current quote.