Effect of ash composition on adsorption and agglomeration characteristics in low-low-temperature electrostatic precipitator systems

The low-low temperature electrostatic precipitator (LLT-ESP) has been applied in many power plants to improve the emission performance. In this study, a number of fix-bed experiments were conducted, which simulated the operation condition of LLT-ESP. The effect of chemical composition on the adsorption characteristics of ash samples and the agglomeration after adsorption were studied. The results show that the agglomeration of ash particles occurs in three forms, including agglomeration among small particles, adhesion of loose pellets to large particles, and agglomeration among large particles. The capacity of ash particles to adsorb sulphuric acid is less affected by the increase of added amounts of NaCl or KCl. At the same time, the added amount of NaCl or KCl also has little effect on the agglomeration degree of ash particles. The addition of MgO, CaO, Fe2O3, Na2CO3, or K2CO3 from 0% to 13.3%, 22.4%, 23.9%, 18.4%, or 14.2%, promotes the adsorption of sulphuric acid by ash particles from 1.95 mg g(-1) to 7.33, 7.71, 6.72, 5.1, or 5.44 mg g(-1) (based on sulphur content), respectively, thereby promoting the agglomeration between ash particles. As the addition amount increases, the agglomeration phenomenon among particles becomes more conspicuous. The form of agglomeration changes from agglomeration among small particles to agglomeration among large particles. In addition, the addition of MgO or CaO has great influence on the adsorption and agglomeration.