Experiment and thermodynamic analysis on Q-phase cement clinker cogeneration from coal in pulverized coal combustion boiler

Abstract

Taking Changguang coal as experimental coal type, carrying out the experiment of Q-phase cement clinker co-generated from high-sulfur coal on two-section multiphase reaction test stand and conducting XRD analysis on the mineral composition in co-generation clicker sample, it was found that the major mineral species in compositions of co-generation clinker are 2CaO·SiO 2 , Q phase and calcium sulphoaluminate (3CaO·3Al 2 O 3 ·CaSO 4 ). According to the Gibbs free enthalpy G of state function, conduct thermodynamic calculation on the mineral formation reaction probably occurring in the chemical compositions of Q-phase cement clinker co-generated from Changguang coal, especially, calculate and compare the formation reactions of high-temperature sulfur capture product 3CaO·3Al 2 O 3 ·CaSO 4 and Q-phase that was the characteristic mineral of co-generation, and compare the priority of mineral formation reactions of clicker. The findings show that, according to the chemical composition of clinker, the direct synthesis reaction of 2CaO·Al 2 O 3 ·SiO 2 will firstly occur, followed by the direct synthesis reaction of 2CaO·SiO 2 , the next is the indirect synthesis reaction of Q-phase, and the last is the indirect synthetic reaction of 3CaO·3Al 2 O 3 ·CaSO 4 ; the final main mineral compositions of co-generation clinker should be 2CaO·SiO 2 , Q phase and 3CaO·3Al 2 O 3 ·CaSO 4 ; the conclusion of thermodynamic analysis on co-generation clicker mineral formation reaction basically conforms to the mineral composition in experiment of Changguang coal co-generating Q-phase cement clinker.