Undercurrent: The Alden Blog

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Industrial fluid dynamics insights


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 ...

Venturi Design for a Circulating Dry Scrubber
One of Alden’s key business areas is designing, analyzing, and improving air pollution control equipment for fossil power plants.  Over the last decade, circulating dry scrubbers (CDS) have become a popular way to remove SO2 and other acids from the flue gas of coal-burning power plants.  A few of the benefits of CDS technology include a relatively low cost of installation, high removal efficiency, low water usage, and no wastewater that needs to be treated – in fact it can be a means to dispose of other wastewater from the plant. The technology works by injecting lime powder into a reaction vessel, and also spraying in a small amount of water (Figure 1).  The water coats the lime particles and eventually evaporates, which helps to improve acid removal.  The powder is suspended in the reaction vessel and mixed using a high velocity stream of flue gas entering from the bottom of the reactor.  Once mixed and reacted, the gas carries the solids out through the top of the reactor into a fabric filter, which acts like a vacuum bag to ...