Wet Stack Design and Operation is the Subject of the Hot Topic Hour on Friday,
Nov. 20, 2009
The use of Flue Gas Desulfurization (FGD) systems has increased worldwide and with the wetter flue gases from an FGD come problems of corrosion of downstream equipment, liquid discharge and dispersion of the gases. One method of avoiding these problems is to reheat the water saturated flue gas emitted by the wet FGD system. However, stack gas reheat systems are expensive to operate, often ineffective in preventing the corrosion of downstream equipment and are typically the primary cause of most problems and high maintenance cost within the FGD process. An alternative is to use an all wet duct and stack system. The disadvantage of wet stacks is the danger of corrosion and liquid discharge if they are not properly designed.
Factors that most affect wet stack operation are stack diameter, flue gas velocity, and the flow of condensed liquid on typical liner materials. The sources of liquid in a wet stack are mist-eliminator carry-over, condensation due to cooling by ambient air, and condensation due to adiabatic expansion along the height of the stack. Trouble-free operation of an FGD unit with wet ducts and stacks requires consideration of the collection, handling and discharge of condensed liquid during the design of the stack.
The following speakers will discuss the issues to consider when designing and installing a wet stack:
David Anderson, P.E. Vice-President, Alden Research Laboratory, Inc. (ARL) and Lewis Maroti, Senior Technical Consultant at ARL. Liquid collectors and drains are needed in most coal-fired units when operating with wet flue gas desulfurization systems. Understanding and properly applying the physics and thermodynamic related to wet operation are essential for the development of effective liquid collection systems. Physical flow modeling is a powerful tool to minimize the liquid discharge from the stacks. Physical flow models will ensure that site specific geometry and arrangement issues are properly addressed and accounted for.
James L. Naylor, III Vice-President, Marketing and Sales, Pullman Power LLC will discuss structural considerations when designing and installing liquid collection systems for wet stacks.
Paul Nederlof, Vice-president, Sales & Operations, Hadek (Penn Iron Works, Inc.) will discuss the proper design of a wet stack and operational benefits that come with a good design.
To register for the “Hot Topic Hour” on Friday, Nov. 20, 2009 at 10:00 a.m. CST (Chicago time), click on: http://www.mcilvainecompany.com/brochures/FGDnetoppbroch/Default1.htm.
Bob McIlvaine
President
847 784 0012 ext 112