Sanitary Treatment Exhaust Heat Recovery Case Study
Rock River Water Reclamation
Rockford, ILUSA Heat Exchange Focus:
UTR1 - U-Tube Recovery 1 Series (3 units)
Installation consists of three Cain UTR1-605I18SSS heat transfer models. Each unit is recovering 1,363,000 BTUs per hour from its paired digester gas fired engine generator. The heat sink temperature of the glycol/water loop (280 GPM) is being raised from 210°F to 221°F by reducing the engine exhaust gas temperature from 852°F to 377°F (2,344 SCFM).
Payback vs. Fuel Savings (per unit)
Unit Cost: $27,620
Payback: 7.8 Months
Annual ROI: 153%
Annual Fuel Savings: $42,231
Life Expectancy Fuel Savings: $844,620 (20 years)
Summary:
The Rock River Water Reclamation District covers nearly 88 square miles of Winnebago County and serves over 250,000 people. During the treatment process, the anaerobic digester speeds up the breakdown of solid waste which produces methane gas. This gas is used as a fuel to operate 3 engine generators. The heat is recovered from the generator by Cain heat recovery units and is used to help heat the digester. The facility saves the district approximately $40,000 each month in electricity.
