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Foaming is a common phenomenon in industrial processes, including wet flue gas desulfurization (FGD) plants. A systemic investigation of the influence of two foaming agents, sodium dodecyl sulphate (SDS) and egg white albumin (protein), and two commercial antifoams on a wet FGD pilot plant operation has been carried out. Foaming caused by 0.03 g SDS/(L slurry) reduced the desulfurization degree from 84 to 74% and the solids and limestone concentrations of the slurry from 58 to 48 g/(L slurry) and from 1.4 to 1.0 g/(L slurry), respectively. These effects were attributed to the foaming transferring small particles to the foam layer present on top of the slurry in the holding tank. The addition of 0.03 g antifoams/(L slurry) to SDS foam eliminated the foam, but the desulfurization degree remained low. Potential mechanisms for the observed behavior are analyzed. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2382–2388, 2014

Spontaneous foaming can cause a range of operational problems in industrial processes such as wet flue gas desulfurization (FGD). This work investigates the performance of selected antifoaming agents (Nalco FM-37, Foamtrol 2290, and rapeseed oil) on foams generated by egg white albumin (protein), sodium dodecyl sulfate, and adipic acid at conditions of relevance for wet FGD plants. The addition of antifoaming agents breaks any existing foam and causes an induction period without foaming, after which the foam gradually will begin to reappear. Foaming by egg white albumin (2 g/L) at 0.014 m/s could be controlled by both commercial antifoaming agents (6.4 g/L), but not by rapeseed oil addition. Foaming by pure commercial antifoaming agents has also been demonstrated: up to 7 × 10−2 m foam was observed with 6.4 g/L Nalco FM-37. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3741–3747, 2013

The aim of this work is to study the influence of nucleation, growth and breakage on the particle size distribution (PSD) of gypsum crystals produced by the wet flue gas desulfurization (FGD) process. The steady state PSD, obtained in a falling film wet FGD pilot plant during desulfurization of a 1000 ppm(v) SO2 gas stream, displayed a strong nonlinear behaviour (in a ln(n(l)) vs. l plot) at the lower end of the particle size range, compared to the well-known linear mixed suspension mixed product removal model. A transient population balance breakage model, fitted to experimental data, was able to model an increase in the fraction of small particles, but not to the extent observed experimentally. A three-parameter, size-dependent growth model, previously used for sodium sulphate decahydrate and potash alum, was able to describe the experimental data, indicating either size-dependent integration kinetics or growth rate dispersion. © 2009 American Institute of Chemical Engineers AIChE J, 2009