In order to further increase the economy of SO_2 ultra low emission

an experimental study on matching strategy of dry desulfurization and semi-dry flue gas desulfurization for a 300 MW unit circulating fluidized bed(CFB) boiler was carried out. The results show that

the dry desulfurization gradually deviated from the high efficiency desulfurization range as the boiler load increased

and with the same desulfurization efficiency

the calcium sulfur ratio increased and the limestone utilization rate decreased. As the boiler load increased

it reached the high desulfurization range of semi dry flue gas desulfurization gradually

and with the same desulfurization efficiency

the calcium sulfur ratio decreased and the lime hydrate utilization rate increased. The desulfurization efficiency of the two-stage desulfurization system can reach above 99% and that of the semi-dry desulfurization method can reach up to 95%. The multi-parameter strategy has better economy than the single SO_2 factor matching strategy. The combined desulfurization in the furnace and outside the furnace can further lower the SO_2 emission

and has good SO_2 emission stability and regulating flexibility.