Investigation on Formation Mechanisms of Ash/Deposit from Cotton Stalk Vibrating Boiler Combustion Based on Their Characteristics

The formation mechanisms of ash/deposit from cotton stalk (CS) water-cooled vibrating grate boiler combustion were explored according to the characteristics of ash/deposits. Measurements of the ash fusion characteristics indicate the ash fusion temperature under oxidizing atmosphere (O 2 /CO 2 , 3:7 volume ratio) increase in the order bottom ash (B cs ) < fly ash (F cs ) < deposit on the super-heater (D cs ) < CS, while the sintering temperatures decrease in the order F cs > B cs > D cs > CS. This results from the ash-composition differences in basic/acid. Potassium feldspar and anorthite were found in F cs ; the sulfates (from chlorination and vulcanization of K or Ca during combustion) presented in D cs was closely related to deposit formation; and calcium silicate and gehlenite were found in the B cs . The F cs was composed of small prismatic particles with surface molten. In the D cs , only the small spherical particles attached to aggregates were molten, whereas the B cs contained mostly molten particle. Formation mechanisms of ash/deposits were deduced from the perspective of inorganic migration and transform during combustion, and the four-layer D cs structure was also proposed