During the operation of SCR flue gas denitrification system in coal-fired units

ammonium bisulfate(ABS) in flue gas causes ash scale slabbing at the cold end of the air preheater and increases the difficulty of purging and cleaning ash. To this end

ABS premixed ash samples were prepared and pressed and heated at different temperatures

and a new test method was designed to compare the changes in compressive strength of the samples and explore the influence law of ABS on the mechanical strength of ash scale. The experimental results showed that: 1) ABS premixed ash samples underwent physical agglomeration and chemical reaction during the heating of slabbing at 147-220 ℃

and the compressive strength was increased by about 95.50% at maximum

among which physical agglomeration played a dominant role with about 88%-89% influence and the influence of chemical reaction accounted for about 10%-12%; 2) ABS slabbed ash samples under heating at 220-300 ℃

ABS vaporization precipitation rate reached up to 96.43%

the ash sample from the slab state to loose

compressive strength from 195.50% of the blank sample to 110.17%. It is proved that the means of high temperature heating is feasible to reduce the ABS content in the blockage and create conditions for improving blowing and cleaning from the perspective of ash scale.