There are some problems during application of low-low temperature economizer in coal-fired units

especially the safety problem in units firing high-sulfur coal.Thus

an experimental platform of lowlow temperature economizer for high-sulfur coal units was built and used to investigate the simultaneous removal of SO_3 from flue gas.The experimental results are as follows.For different kinds of coal

the conversion ratio of SO_2 to SO_3in flue gas were about the same

which was 1.5%.When the temperature of flue gas at the end of the test section of the self-built low-low economizer was below the acid dew point

the simultaneous removal ratio of SO_3 were from 70.9%to 91.9%

indicating the removal effect was dramatic.When the concentration of fly ash in flue gas was high enough

the simultaneous removal ratio of SO_3 increased as the ratio of ash to sulfur decreased

and when the ratio of ash to sulfur were above 150

the simultaneous removal ratio of SO_3 were tending to be stable.Meanwhile

when the outlet temperature of flue gas was below the acid dew point

the outlet temperature had no significant effect on the simultaneous removal ratio of SO_3.Through the application of SO_3 flue gas conditioning

the order magnitude of the fly ash resistivity at the outlet of the test section decreased to 1.08×10~9 to 5.1×1 0~(10) Ω·cm

which was at the high efficient ash removal range and would benefit the efficient removal of the fly ash.