Does a producer gas kiln cut fuel use in a Jodhpur lime kiln?

It cuts heat use more than fuel weight. The SAMEEEKSHA project report for Jodhpur lime puts a pet coke kiln at 1,530 to 1,650 kcal per kg of quicklime, against 1,100 to 1,200 for a coal-fired producer gas kiln; theory needs 900. But the gas kiln burns about 220 kg of coal per tonne, against 180 kg of pet coke.

What the report compares

• Heat per kg of quicklime: 1,530 to 1,650 kcal on pet coke, 1,100 to 1,200 kcal on producer gas, against a theoretical 900 kcal.
• Fuel per tonne of finished product: 180 kg of pet coke today, about 220 kg of bituminous coal through the gasifier.
• Material lost per tonne: 5 to 10% on pet coke, nil with producer gas, by the report's figures.
• Electricity: no saving; the gasifier does not change the kiln's power use.

The gasifier the report specifies

For a 15 to 30 tonnes a day kiln: 1,000,000 kcal an hour of gas at 1,250 to 1,350 kcal per Nm3, made from about 4,750 kg of coal a day. The coal is 5,200 to 5,500 kcal/kg, sized 15 to 70 mm, with ash fusion at 1,400 °C. The report adds that the gasifier can also run on rice husk briquettes.

The cluster today

• About 100 lime units, every kiln on pet coke; on average 3 t of pet coke makes 15 t of quicklime, about 0.2 t of 7,400 kcal/kg pet coke per tonne.
• Medium units, 65 to 70 of them, make 5,000 to 15,000 t a year; 10 to 15 small units make under 5,000 t; 2 to 5 large units make more than 15,000 t.
• Motors use 14 to 16 kWh per tonne of hydrated lime.
• The report judges about 60% of units able to take up the technology.

Before you switch

1. Weigh fuel per tonne of quicklime on your own kiln for a month, so you have a baseline that is yours, not the cluster's.
2. Ask the gasifier supplier for coal per tonne of lime at your output, in writing.
3. Remember the limestone's own CO2 does not change; only the fuel share can fall.
4. If you move to rice husk briquettes, record them separately: biomass CO2 is reported apart from fossil CO2.

Estimate: fuel CO2 per tonne of quicklime

• Pet coke kiln: 180 kg x 3.17 kg CO2/kg (IPCC default) = 571 kg CO2
• Producer gas kiln: 220 kg coal x 5,350 kcal/kg = 1.18 Gcal = 4.93 GJ
• 4.93 GJ x 85.2 to 90.6 kg CO2/GJ (CEA, imported and Indian coal) = 420 to 447 kg CO2
• Fuel CO2 falls by about 124 to 151 kg per tonne, roughly 22 to 26%

Estimate. 5,350 kcal/kg is the midpoint of the report's coal range; CEA's coal factors are on a gross calorific value basis. Your own coal analysis gives the real figure.

What Senseible does here

Senseible reads pet coke and coal purchase invoices into monthly fuel records, so a trial month on producer gas can be set against a pet coke month on tonnes actually bought.

• Your MSME carbon number
• Jodhpur lime units: CO2 per tonne
• Lime kiln insulation and pet coke
• CEA's CO2 factors for Indian coal

Sources: BEE SME programme (SAMEEEKSHA), Detailed project report: gasifier for 15 TPD lime kilns, Jodhpur cluster, CEA, CO2 Baseline Database User Guide version 22.0, Appendix B, IPCC 2006 Guidelines, Volume 2 Energy (fuel emission factors)

Last reviewed 2026-11-03.