Air quality control technology at Dry Fork Station

The equipment might look kind of dirty. But these are the building blocks for what will be one of the cleanest coal-based power plants in the country. And a team from Basin Electric went to Germany twice to do research on how to run this technology to its highest potential.

(Joel Dingman/Operations superintendent): This air quality control system is state of the art for plants of this type in the United States. Its exciting to be a part of that.

State of the art. For the Dry Fork Station in Wyoming, Basin Electric wouldnt accept anything less.

(Joel Dingman): The best available technology is this scrubber, for SO2 removal.

The scrubber being built at Dry Fork is a reflux circulating fluid bed dry scrubber. Its dry because it uses far less water than some other sulfur dioxide absorption systems. Water and lime are mixed together. The water and dry lime mixture are sent into the scrubber vessel you can see part of the vessel here. At the same time, these nozzles increase the velocity of the gas that comes out of the boiler - into the scrubber vessel. The flue gas, water and lime have a chemical reaction. The sulfur dioxide is removed from the flue gas during the reaction. The flue gas contains ash and a little bit of lime thats pulled to the baghouse. These are the baghouse compartments it works like a huge vacuum cleaner. When the bags are shook to release the ash and lime, it falls into hoppers, and is sent back to the scrubber vessel. The product is recirculated to ensure maximum efficiency.

(Joel Dingman): The goal will be to use as high a percentage of the lime as possible so that its all inert when it becomes a waste product.

The technology comes from Germany. About 1.8 million cubic feet of flue gas will travel through the scrubber every minute. The best monitors available will be testing for mercury. And even more environmental controls come in the form of over-fire air and low NOx burners. The plant will use selective catalytic reduction for NOx removal; that equipment works like a catalytic converter on a car.
Plus, this plant site is ready for the future if carbon capture ever does become necessary

(Joel Dingman): We tried to make sure that we would save enough space for the equipment that would be needed for that.

The best scrubber technology available and minds thinking toward the future. In fact a quarter of the total cost of this plant is going to environmental controls a sound investment.

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