Zhang Liqi

Integrated Control of Submicron Particles and Toxic Trace Elements by ESPs Combined with Chemical Agglomeration

Enrichment of typical toxic trace elements As on PM2.5 was investigated through bench scale experiments. Results showed that the vaporization of arsenic in pyrite was easier than in arsenate form. Along with increasing temperature from 1100°C to 1400°C, arsenic content in PM2.5 increased from 0.09 mg/Nm3 to 0.35 mg/Nm3. Then, a novel Electrostatic precipitators (ESPs) combined with chemical agglomeration technique was developed to control the emission of PM2.5 and toxic trace elements. PM2.5 enriched toxic trace elements are agglomerated by some new chemical agents injected as an aqueous solution upstream of ESPs and come into being conglomerations which can be captured by ESPs easily. Systematic experiments of PM2.5 agglomeration showed that chemical agglomeration was a useful method to promote growing up process of submicron particles, XTG was the most effective agglomerant. Resistivity tests revealed that agglomerants could make fly ash resistivity two orders lower at certain concentration, would improve the performance of ESPs with resistivity related performance problems.

Agglomeration Modelling of Sub-Micron Particle during Coal Combustion Based on the Flocculation Theory

The monte carlo method was used to simulate chemical agglomeration of sub-micron particle which based on the flocculation model of the water processing, the influence of different agglomeration solution volume on sub-micron particle agglomeration was investigated. Simulation results show that the growth of particle mean diameter and the decrease of particle number are fast at the initial stage of agglomeration, and the speed of them increase with agglomeration solution volume increasing. After achieving stability, as a whole, the particle mean diameter is almost in proportion to agglomeration solution volume. At the last stage of agglomeration, particle number follows a similar bimodal distribution, which is varying with different agglomeration solution volumes. When agglomeration solution volume is 2 ml/min, the peak value of diameter is the biggest.