The efficiency of sulfur reduction in combustion processes depends on many variables like combustion temperature, excess of air, air staging, fly ash re-circulation, fuel type, limestone characteristics, limestone and fuel feed distribution and Ca/s ratio. The study examines how some process variables and fuel characteristics affect sulfur reduction efficiency. CFB combustion tests were performed in order to measure and characterize effects and interactions. Coal and bark co-firing tests were performed with a laboratory-scale CFB combustor. The objective of the tests was to find out the effects of following factors and parameters on sulfur removal: bark fraction in fuel feed, riser temperature, air excess and Ca/S ratio in the fuel blend. The coal/bark blends tested contained 0, 30, 40 or 50% of bark on energy basis. Corresponding sulfur removal efficiencies were from around 25% (no bark) up to 60% (50% bark). The riser bottom temperature also had a very strong effect on sulfur removal. A sharp decrease in SO2 emissions was observed when the riser bottom temperature was decreased from 900 to 870 ºC. Limestone was added as a sorbent in some co-firing tests corresponding to Ca/s ratios between 1 and 2. Resulting sulfur reduction varied from 60 to 75% respectively.
|Title of host publication||The Proceedings of the 27th International Technical Conference on Coal Utilization and Fuel Systems|
|Subtitle of host publication||Clearwater, FL, USA, March 4-7, 2002|
|Publisher||Coal Technology Association|
|Publication status||Published - 2002|
|MoE publication type||Not Eligible|