Electrostatic Precipitator Performance Optimization
Our team and Air Consulting Associates (ACA) were was contracted by Southern Environmental Inc. (SEI) for the planned Electrostatic Precipitator (ESP) upgrades for a large US utility. Our team performed the upfront physical flow model studies while ACA proivded technical support throughout the entire project.
An ESP operates by electrically charging ash particles in the fluegas and then attracting the charged particles onto collecting plates which are then rapped to send the ash to the hoppers where it can safely be removed from the system. For optimum system operation, the distribution of the gas velocity must be very uniform entering the ESP to maximize the collection efficiency of the ESP and to minimized particulate emissions. Upstream duct fallout of ash particles and the flue gas distribution into the ID fans are also important components of ESP operation that must be considered to inhibit premature outages.
Work Performed
Physical flow modeling techniques were used to develop and optimize duct and ESP flow controls and ash handling devices to achieve best performance targets for ash removal. The connecting ductwork from the existing air preheaters to the rebuilt ESPs were also included in the studies to provide flow controls designs to optimize air preheater performance. The model simulated the field gas velocities, pressure losses, and ash particulate transport and removal.
Results
Not only did we design a cost-effective design for the flow controls and perforated plates to provide optimal ash removal, our recommended design achieved the ICAC EP-7 targets for uniformity of flue gas velocities at the inlets to the first collecting fields and at the outlets of the last collecting fields to maximize particulate removal efficiency
Each of the three units passed their respective performance test guarantees after the recommendations from the physical flow model had been implemented.
Capability
Civil InfrastructureServices
Gas Flow Modeling & DesignRelated Projects
Between 1932 and 2010 the state of Louisiana has lost about 2006 square miles of land due to a combination of subsidence, sea level rise, and management of the Mississippi River. Computer models predict a further loss of 1800 to 4200 square miles in the next 50 years, amounting to 55% of the land in Plaquemines Parish and resulting in $300 million in annual economic damage. Following hurricanes Katrina and Rita, the Coastal Protection and Restoration Authority (CPRA) was formed as a single state entity with the authority to protect and restore the lands of coastal Louisiana.
The $50 billion coastal master plan includes restoration and risk reduction projects. The restoration projects include barrier island restoration, hydrologic restoration, marsh creation, ridge restoration, sediment diversion, and shoreline protection. The Barataria and Breton Basins have experienced some of the largest land loss—almost 700 square miles. Two sediment diversions are being designed, one for each basin. The sediment diversions connect the Mississippi River to the basins, allowing for the controlled diversion of up to 75,000 cfs of water and sediment to the Barataria basin and 30,000 cfs to the Breton basin.
The design and construction of sediment diversions on the scale proposed for Barataria and Breton is unprecedented, the results of which will rely heavily on the numeric and physical modeling required to design the major diversion features, including the inlet, conveyance, and outlet structures. Alden is constructing two 1:65-scale, live-bed physical models to test performance and effectiveness of the diversions.
Discover more:
- Making Mississippi Mud In Massachusetts To Restore Wetlands | Here & Now [wbur.org]
- A Mini Mississippi In Mass. May Help Save New Orleans From Rising Seas [90.9 Boston NPR]
- Rerouting the Mississippi River could build new land—and save a retreating coast [Science Magazine]
- Find the Mississippi River in Massachusetts [Chronicle 5 WCVB]
- To Save Louisiana’s Vanishing Coast, Build a Mini Mississippi Near Boston [The New York Times nytimes.com]
- Louisiana researchers tackle a changing Mississippi Delta [PBS News Hour Weekend pbs.org]
- Mid-Barataria Sediment Diversion could create, save 47 square miles of land over 50 years [nola.com]
- CPRA Using Giant Model to Test Mid-Barataria Diversion
- Mississippi River Diversions Could Save Louisiana's Drowning Coast [enr.com]
- Louisiana Coastal Protection and Restoration Authority [Official Website]
- A Mini-Diversion in Boston is Paving the Way for Louisiana’s Boldest Coastal Project [mississippiriverdelta.org]

Civil Infrastructure
Mid-Barataria Sediment Diversion
Alden constructed two 1:65-scale, live-bed physical models to test performance and effectiveness of the proposed land rebuilding diversions on the Mississippi River.
The Cedar Cliff dam and hydropower project is located approximately six miles from Cullowhee, in Jackson Country, North Carolina. The dam and hydroelectric facility is owned by Duke Energy and is located downstream of three other hydroelectric projects that are operated as a system.
The primary spillway includes a Tainter gate and the existing auxiliary spillway system includes two fuse plug sections (with different crest/activation elevations). It was determined that the combination of the primary and auxiliary spillway systems were not adequate to safely pass the regulatory-increased Inflow Design Flood (IDF). The construction of a Hydroplus Fusegate system with six semi-labyrinth Fusegates in an enlarged auxiliary spillway channel was selected to increase spillway capacity to safely pass the new IDF which is now the full Probable Maximum Flood (PMF).
Two reduced scale physical models were constructed to determine the required size of a ventilation system for the proposed Cedar Cliff Fusegates and headpond and tailwater levels at each Fusegate for flows up to the sixth Fusegate activating. The tailwater levels were required for design of the Fusegate ballast system.
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Civil Infrastructure
Cedar Cliff Spillway
Physical model study to determine hydraulic performance of a proposed auxiliary spillway system during flooding events