(22c) Modeling Paste Transport Systems for Flue Gas Desulphurization Water Disposal

Encapsulation paste is a new zero liquid discharge solution for flue gas desulphurization (FGD) wastewater, that is being considered by a variety of coal-fired power plants across the country. “Paste” is an encapsulation agent that is produced by mixing fly ash, quick lime, and FGD water, creating a pumpable pseudo-plastic. This fluid quickly cures to become an impermeable solid, in turn, trapping hazardous heavy metals from the FGD water.

Given the difficulties of its shear thinning and time-dependent cementitious behavior, coupled with pumping distances of up to one mile; understanding the complex rheology of the material is vital to the pumping design. Using a rotational rheometer and a modified rheological model, we can quickly predict the variable head loss across a system as a bench scale test.

This calculation can then be used to estimate the energy costs, pump size, and material costs of a full-scale pumping system at a variety of simulated piping conditions and mix designs from a sample as small as 100 grams. While applied to encapsulation paste in this study, this same general model can be utilized with other non-Newtonian fluids to predict the head loss across a system and optimize the respective transport process.