Deep Breath: The Impact of Alden's Work on Power Plant Emission Controls

Each year, National Engineers Week falls on the week of February 22 — George Washington’s actual birthday—in part to commemorate a man who is considered the nation’s first engineer. But not only that, the week is meant to highlight the contributions engineers have made to the world as we know it. Just think about that for a minute as you read this on a display screen that wouldn’t exist if not for engineering ingenuity. The list of accomplishments engineers have made to our society and the history books is massive.

From our perspective, we can highlight many areas in which Alden engineers have contributed to the annals of history. From testing airplane propellers and missile ballistics to the work on dam safety and fish passage and protection programs, we’ve had a hand in shaping our world throughout our 125 years of continual operation.

But trying to find a singular project to discuss for this week? That task is nearly impossible. So, that’s when I asked Dave Anderson, Senior Vice President and Chief Technology Officer to weigh in.  Besides wanting to know where his present for National Engineer’s Week was (in the mail, of course), he offered some great insight.

“If I had to point to one thing we’ve done at Alden that has had the biggest impact on society – each and every one of us—it would be our work on power plant emission controls,” Dave says. “While we have made incredible contributions in so many areas, nothing is as important as the air you and I breathe.”

Dave is referencing the flow modeling work we’ve done to help design, integrate, and optimize the performance of emission control systems to meet clean air standards. 

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The Clean Air act has evolved throughout the years along with the research and techniques for controlling and monitoring power plant emissions. As programs and provisions were rolled out, the role of flow modeling and the subsequent design work needed to make emission control systems run efficiently became even more critical. And that’s where our engineers coupled their technical expertise with laboratory modeling techniques that use state-of-the-art computational fluid dynamic (CFD) modeling and traditional reduced scaled physical modeling to provide realistic, reliable solutions for each and every project.  

Our engineering design, investigation, and evaluation of flow-related systems include experience with NOx, SOx, Hg, particulate collection system design and operation, carbon capture and sequestration, stack liquid discharge, dust deposition and entrainment, system optimization and pressure loss reduction.

For instance, we used computational and scaled physical modeling to simulate a planned Selective Catalytic Reduction system (SCR ). The objective of the project was to design internal flow controls and an ammonia injection system to optimize the NH3:NOx ratio entering the catalyst layers, ensure uniform flue gas velocity & temperature distributions within the catalyst, minimize the potential ash deposition, and reduce the non-recoverable pressure losses through the SCR system.

In another study, Alden engineers used CFD and scaled physical modeling to evaluate and optimize the performance of a planned Wet Flue Gas Desulphurization (WFGD) design  by simulating the flue gas flow distributions entering and throughout the WFGD spray tower. Modifications to the inlet ductwork and within the WFGD were made to improve the gas flow and SO2 removal efficiency. The results of the study provided flow controls and a spray nozzle injection grid design to minimize liquid pullback while providing uniform spray coverage, which resulted in optimized SO2 removal.

Another client contracted us to design a quench spray header system to reduce stack inlet temperatures in order to protect a Pennguard lining during Flue Gas Desulphurization (FGD) bypass mode. Our team used CFD simulations to design a quench system that not only lowered the stack inlet gas temperature, but ensured full evaporation of the injected liquid, avoided wall wetting, and minimized gas temperature gradients entering the stack. Read more about the bypass quench system design here.

We have also used scaled physical modeling to simulate a planned Electrostatic Precipitator (ESP) upgrade and to design flow controls and perforated plates to optimize the flue gas velocity distribution entering the collection fields, minimize ash re-entrainment from the collection hoppers, and reduce the non-recoverable pressure losses throughout the system.

So what’s the end result of all this work and countless other emission control projects that have passed through our doors over the years? You’re breathing it. And for that, we can say it’s truly our contribution to making the world a better place for all of us.

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