Does the Surat manual's heat recovery on 300 units save 50,000 tonnes of coal or 87,600?
The Bureau of Energy Efficiency (BEE) Surat manual prices a jet machine drain heat exchanger at 292 tonnes of coal and rupees (Rs) 10.22 lakh a year for each unit. For about 300 units it prints 50,000 tonnes and Rs 1,750 lakh; 300 times 292 is 87,600. The unit's 292 is 886 kilograms times 330 days, not 350.
One unit, as printed
- Hot water drained: 85,000 litres a day, 68,000 taken as the conservative 80%. Temperature 90 degrees Celsius. Heat recoverable 27,20,000 kilocalories (kcal) a day. Operating days 350.
- Boiler efficiency 51%, coal at 5,800 kcal a kilogram (kg), fuel saved 886 kg a day, 292 tonnes a year at Rs 3,500 a tonne: Rs 10.22 lakh (1 lakh = 100,000). Investment Rs 6.00 lakh. Payback printed as 6 months.
The cluster line against it
The text says the scheme can be implemented in about 300 units, saving 50,000 tons of coal and Rs 1,750.00 lakh a year, for Rs 1,800.00 lakh, with payback around one year.
Investment rebuilds: 300 x 6.00 = 1,800. Savings do not. 300 x 292 = 87,600 tonnes, not 50,000; 300 x 10.22 = Rs 3,066 lakh, not 1,750. The printed 50,000 and 1,750 both fit 171 units (50,000 / 292 and 1,750 / 10.22). So the cluster saving looks like 171 units' worth and the cost like 300 units'. The manual does not say why.
Which way it runs: at 300 units and 292 tonnes, the cluster payback is 1,800 / 3,066 = 0.59 years, about 7 months, which matches the single unit. The printed 'around one year' is the cautious one.
Small differences inside the unit table
- 886 kg x 350 days = 310 tonnes. 292 tonnes is 886 x 330 days, so the days line and the tonnes line do not use the same year.
- At 51% and 5,800 kcal the heat gives 27,20,000 / 0.51 / 5,800 = 920 kg a day, not 886. At 6,000 kcal it is 889.
- Payback 6.00 / 10.22 = 0.59 years, 7.0 months, printed as 6.
What to take from it
Use your own drain volume and temperature, your own days, and your invoice price. Do not multiply the per-unit saving by a cluster count and quote the product as a result: it is a potential, not a measured saving.
The two cluster totals side by side
- Printed: 50,000 tonnes, Rs 1,750 lakh, Rs 1,800 lakh invested
- Units implied by savings: 50,000 / 292 = 171; 1,750 / 10.22 = 171
- Units implied by cost: 1,800 / 6.00 = 300
- At 300 units: 300 x 292 = 87,600 tonnes; 300 x 10.22 = Rs 3,066 lakh; payback 1,800 / 3,066 = 0.59 years
Inputs are the manual's, at its year's prices. The reading of 171 and 300 is our arithmetic.
What Senseible does here
Senseible reads fuel invoices and electricity bills into monthly records, so the coal bought each month is on file, ready to test a saving against your own tonnes. It does not measure drain water or heat; that needs a flow and temperature log.
Sources: BEE, Manual on Energy Conservation Measures in Textile Cluster, Surat (SAMEEEKSHA)
Last reviewed 2026-11-06. Figures are the manual's, at its year's prices. Measure your own drain volume and temperature before sizing.