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JEA’s Northside Generating Station (NGS) produces approximately 40 percent of our electricity.
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JEA’s Northside Generating Station (NGS) is located in Jacksonville, Florida. The two circulating fluidized bed (CFB) boilers at NGS are fired with petroleum coke blended with coal. Limestone is also added to create thermal mass and as a scrubbing medium to remove sulfurous gases. During the firing process, two byproducts are generated: fly ash and bed ash. |
Northside Repowering
In 2000, NGS units one and two were repowered, or converted, to use solid fuels – coal and petroleum coke – instead of oil. This was accomplished by switching to circulating fluidized bed (CFB) technology for the boiler design allowing the use of solid fuels while controlling sulfurous emissions. The benefits of the NGS repowering include:
- Lower fuel cost
The cost of generating electricity with solid fuel is currently half that of the next lowest cost fuel (natural gas).
- Increased generation capacity
Utilizing the CFB design increased generation capacity of NGS by 50 percent.
- Reduction in emissions
Even with increased generation capacity, repowering with CFBs reduced NGS emission levels by 10 percent.
- Production of useable byproducts
Unlike conventional solid fuel boilers, in the CFB process limestone is fed into the boiler along with the solid fuel. A unique byproduct (ash) is produced comprised mostly of residual limestone. Properly processed, this byproduct is an excellent substitute for traditional civil construction materials including limerock, concrete, recycled concrete and asphalt. JEA has two products that are produced from electric generation byproducts. They are EZBase® and EZSorb®.
What is Ash Byproduct?
Our Northside Generating Station (NGS) burns solid fuels typically in ratios of 90 percent petroleum coke to 10 percent coal. Limestone is added with the fuel in the boiler during the power generation process to create thermal mass and to aid in the removal of sulfurous gas emissions.
- Two Kinds of CFB Ash
- Bed Ash
The byproduct produced from the boiler is bed, or bottom, ash. In addition, lime slurry is fed to the flue gas (stack) in a dry spray tower polishing scrubber system to further reduce sulfurous gas emissions.
- Fly Ash
The byproduct produced from the stack is fly ash. While the elemental composition of the both types of ash are similar, they vary greatly in weight and particle size. (see photo)
Byproduct (ash) from a solid fuel CFB plant, such as the JEA NGS facility, is not the same as byproduct from a conventional boiler that uses pulverized coal or fuel oil.
JEA’s CFB ash is composed primarily of lime and gypsum (calcium oxides and calcium sulfate, respectively). That means that less than 10 percent by weight of our CFB byproduct actually represents what would generally be termed “ash” from combustion of the fossil fuels. Over 90 percent by weight of CFB byproduct is a result of the addition of the limestone to the boilers. JEA’s CFB byproduct ash is not an “ash” in the typical sense, and is not solely the remnant material from conventionally-fired boilers. It is primarily limestone.
Please contact us for more information.
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