Performance tests have been carried out on two yellow straw biomass firing boilers with vibrating gate

the measured boiler efficiency is 85.90% and 86.71

the concentration of NOx emission is 180 mg/m3 and 181 mg/m3(6% O2)

the concentration of SO2 emission is 196 mg/m3 and 269 mg/m3(6% O2) respectively.The study shows that the main causes leading to lower boiler efficiency are as follows:lower calorific value of fuel due to higher water cotent and ash content in the fuel;higher discharged flue gas temperature resulting from ash fouling on the finned type flue gas cooler and tube blockage after low temperature corrosion;higher carbon content in ash and slag

and higher CO content in the discharged flue gas.Based on the results of tests

several measures

such as retrofitting the primary air box and flue gas cooler

optimizing the operation mode

and enhancing the quality of fuel etc.

have been put forward

so as to heighten the boiler efficiency.