Verdantas Flow Labs was engaged by a confidential client to evaluate and improve the wet stack performance of a coal-fired generating unit in the Midwest. The client was preparing to retrofit the unit with a wet flue gas desulfurization (FGD) system and planned to line the existing concrete stack with Pennguard borosilicate block. The goal was to assess the potential for stack liquid discharge (SLD) and design a system that would ensure long-term operational reliability.

Our team conducted a comprehensive physical flow modeling study using a 1:16.12 scale model of the absorber outlet ductwork and stack. The model was used to simulate gas-liquid interactions under various operating conditions, including full-load scenarios. We evaluated baseline flow behavior and tested multiple configurations of liquid collection devices to identify the most effective design for capturing condensate and entrained liquid.

The study revealed areas of concern related to re-entrainment and liquid film behavior, particularly in the lower stack and duct transitions. Based on these findings, we developed a custom liquid collection system that included multiple collector rings, turning vane drains, and pressure-balanced seal pots. The final design was validated through model testing and optimized to minimize SLD while accommodating the unique geometry and flow characteristics of the unit.