Corn Stover and Wheat Straw Combustion in a 176-kW Boiler Adapted for Round Bales

Combustion trials were conducted with corn stover (CS) and wheat straw (WS) round bales in a 176-kW boiler (model Farm 2000). Hot water (80 C) stored in a 30,000-L water tank was transferred to a turkey barn through a plate exchanger. Gross calorific value measured in the laboratory was 17.0 and 18.9 MJ/kg DM (dry matter) for CS and WS, respectively. Twelve bales of CS (1974 kg DM total, moisture content of 13.6%) were burned over a 52-h period and produced 9.2% ash. Average emissions of CO, NOx and SO2 were 2725, 9.8 and 2.1 mg/m(3), respectively. Thermal efficiency was 40.8%. For WS, six bales (940 kg DM total, MC of 15%) were burned over a 28-h period and produced 2.6% ash. Average emissions of CO, NOx and SO2 were 2210, 40.4 and 3.7 mg/m(3), respectively. Thermal efficiency was 68.0%. A validation combustion trial performed a year later with 90 CS bales confirmed good heating performance and the potential to lower ash content (6.2% average).