How much CO2 does converting a foundry cupola to divided blast save?

Roughly 75 t of CO2 a year in BEE's Batala, Jalandhar and Ludhiana report: fuel per 2.14 t melt drops from 500 kg to 400 kg, or 25 t over 250 melts. The report's own 25 t CO2 figure undercounts. Cost Rs 6.64 lakh, saving Rs 3.95 lakh a year, payback 1.68 years (2011).

The cupola BEE costed

• One melt a day in an 8 to 10 hour shift, 250 days a year.
• About 2.14 t of cast iron a melt at 1,300 to 1,500 C, taking 5 to 7 hours.
• Fuel per melt falls from 500 kg to 400 kg, charge from 2.14 t to 2.10 t, and rejected metal from 140 kg to 100 kg.
• Downtime for the rebuild: 3 weeks.

What a divided blast cupola changes

Blast air enters through two rows of tuyeres about a metre apart, split roughly equally, each row with its own wind belt so pressure and volume can be set separately.

British foundry research quoted in the report found 20 to 32% less charge coke and an 11 to 23% faster melt at the same tapping temperature. A 1988 demonstration cupola in Howrah cut coke by 35% against a poorly designed divided blast unit.

Why the report's 25 t CO2 is too low

The report saves 25 t of fuel a year and lists 25 t of CO2, though its own note gives 2.1 t of CO2 per tonne of fuel, which would be 52.5 t. It calls the fuel coal; cupolas burn foundry coke. At the IPCC default for coke, about 3.02 t of CO2 per tonne, 25 t of coke is about 75 t of CO2. If your invoices really show coal, use your coal's factor.

Before you rebuild

• Get the design worked out for your shell: tuyere area and number, the top to bottom air ratio, blower volume and pressure, well depth and stack height. A copied design loses most of the saving.
• Weigh coke into every charge for a month before and after.
• Track coke per tonne of good castings, not per tonne melted, so fewer rejects show up too.

250 melts a year, before and after

• Before: 500 kg x 250 = 125 t coke x 3.02 = 377.5 t CO2
• After: 400 kg x 250 = 100 t coke x 3.02 = 302 t CO2
• Saved: 25 t coke, about 75.5 t CO2 a year
• Per tonne melted: 500 / 2.14 = 234 kg coke (706 kg CO2) down to 400 / 2.10 = 190 kg (575 kg CO2)

Coke at the IPCC 2006 default, 107,000 kg CO2 per TJ at 28.2 GJ per tonne, an estimate. Blower power and limestone are left out.

What Senseible does here

Senseible reads coke and power invoices into monthly records: tonnes of coke from each invoice, and kWh with CO2 from each power bill. It has no built-in coke factor, so apply the one worked above. The green loan check tells you what a lender will ask for.

• Green loan readiness check
• Cupola CO2 per tonne of castings
• Batala cupola coke per tonne
• Cupola or induction furnace

Sources: BEE, Detailed project report: divided blast cupola furnace, Batala, Jalandhar and Ludhiana foundry cluster (2011, SAMEEEKSHA), IPCC 2006 Guidelines, Volume 2 Energy, Tables 1.2 and 2.3

Last reviewed 2026-10-31. Report figures are from a BEE SME programme project report; costs and paybacks are at the report year's prices. Check today's fuel and power prices before you rely on the payback.