Investigation on removal effects and condensation characteristics of condensable particulate matter: Field test and experimental study.

Condensable particulate matter (CPM) has become the main part of the total primary PM emitted from stationary sources and has aroused increasing concern. In this work, the removal effects of wet flue gas desulfurization (WFGD) on CPM components were studied. A new CPM-containing flue gas system was designed and used to investigate the condensation characteristics of 16 PAHs, sulfuric acid mist and SO conversion into CPM. Some interesting results were obtained and include the following: (i) The removal efficiencies of WFGD on both CPM inorganic and organic fraction reached 81.0% and 67.3%, respectively. (ii) The removal efficiency data obtained for C-C and 5-ring PAHs revealed that organic components with high boiling points and low volatility in CPM are easily removed by WFGD. Condensation experimental results indicated that the condensation ratios of PAHs generally increased with the number of fused benzene rings, while the increase of flue gas moisture content might inhibit the conversion of PAHs into CPM. (iii) The concentrations of SO, Ca, and Na accounted for 48.7% of CPM inorganic fraction after desulfurization, while Ca was barely removed by WFGD. Condensation experiments indicated that most SO in CPM arose from sulfuric acid mist, rather than from sulfate aerosols. Note that only <20% of the sulfuric acid mist belonged to the CPM category, which might help to develop specialized deep purification strategy for SO. In addition, SO could cause a high positive bias for the CPM field test although its condensation ratio was only 2.7%. This work provides a basic reference for subsequent CPM formation and reduction researches.