SAS Incorporated logo

Atlantic Power

Atlantic Power provides bioenergy to Georgia Power to augment 250MW of wind energy and 210MW of solar energy, making Georgia Power one of the nation's largest generators of green electricity. 

The Atlantic Power bioenergy facility includes a "bubbling-staged combustor" located in Barnesville, Ga. that consumes around 500,000 tons per year of forestry by-products (from logging and land clearings) to generate 53.5 MWe.

Project objective

This project involved conducting a CFD analysis of the emissions reduction system consisting of an Over-Fire Air (OFA) system and an Ammonia Injection Grid (AIG) to reduce CO and NOx emissions from the bubbling-bed biomass-fired reactor.  The project aimed to determine the optimum configuration of the OFA and AIG systems to reduce CO and NOx emissions below the current performance levels of 67-75% of 0.84 lb CO/MMBTU, on an annual average basis and 120 ppm NOx). 

In addition, it was an objective that the optimized system would reduce ammonia consumption and reduces wear of the vertical steam tubes caused by rubbing between the OFA nozzles and the steam tubes.

Results

Based on past experience with OFA systems, it was suspected that CO emissions were likely related to poor mixing of the Over-Fire Air with combustion effluent coming from the bed.  Based on the CFD analyses conducted by SAS, a novel “swirling OFA solution” was installed which resulted in a 60% reduction of CO emissions from normal operating levels, prior to installation of SAS' novel solution.  Testing of the NOx reduction system determined that when ammonia flow was turned off, NOx levels reached approximately 120 ppm. 

Following SAS' CFD optimization of the NOx reduction system, NOx levels were reduced from around 1.87 lb NOx/MW to approximately 1.11 lb NOx/MW, for approximately a 60% reduction below normal operating levels. 

This was achieved using less ammonia which resulted in substantial cost savings for the client.

The client has confirmed these results and has concluded:  "Thank you for another great piece of work!"