LA Ash markets the CFB ash products (commonly known as fly ash and bed ash) that remain after combusting petcoke and limestone in CFB steam generators under the names OPF70, OPF90, OPF42, OPF57 and OPF104.

Following are only a few of the many processes for which CFB calcined limestone products can be used:

  • Reduce the plasticity index of clayey soil
  • Neutralize acidic waste
  • Stabilize hazardous compounds
  • Solidify sludge and saturated soils
  • A base course surfaces
  • In some cases, as an alternative to portland cement for soil stabilization

Do not mix OPF products with any other chemicals or byproducts, including but not limited to Cement Kiln Dust (CKD), portland cement or lime, due to certain chemical reactions and/or swell potentials. Questions should be directed to your sales representative.

OPF70, LA Ash’s CFB fly ash brand is a product of coke combustion. OPF70 is unmodified circulating fluidized bed combustion deposit consisting primarily of calcium oxide (CaO) and calcium sulfate (CaSO4).
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OPF90, LA Ash’s CFB bed ash brand is a product of coke combustion. OPF90 (commonly known as bed ash) is unmodified circulating fluidized bed combustion deposit.
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With lower unit weight than limestone and CBRs greater than 100, OPF42 is the easy choice for lightweight material.
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LA Ash’s OPF57 is a manufactured lightweight material similar to 57 limestone.
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LA Ash’s OPF104 is similar to an overburden rock.
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OPF1 is LA Ash’s hydrated lime by-product.

How Are We Different?

What Is Petroleum Coke (Petcoke)?

  • Petroleum coke (petcoke) is a carbonaceous solid residual byproduct of the oil refining coking process. As crude oil is refined, lighter fractions or products, such as gasoline and jet fuel, are driven off leaving a residual oil of relatively little value. In refineries with cokers, this residual oil is processed further to yield additional amounts of light products, along with petroleum coke. Over 75% of the petcoke produced is considered to be fuel grade and has about 15% higher heating value than coal.
  • Some 40 to 60 percent of the sulfur in the oil feedstock remains in the coke, which means that the sulfur content of this refinery byproduct is usually quite high. While the actual amount of sulfur in the coke will vary depending on the sulfur in the crude oil entering the refinery, the sulfur content of coke typically ranges from four to eight percent – much greater than even high-sulfur coal. Therefore, control of sulfur emissions is very important when using as a fuel.

What Is Fluidized Bed Combustion?

  • Fluidized bed combustion (FBC) is a technology used in the design of “clean coal” power plants. It evolved from efforts to find a combustion process able to control pollutant emissions without external emission controls (such as scrubbers). The technology suspends solid fuels on upward-blowing jets of air during the combustion process. The result is a turbulent mixing of gas and solids. The tumbling action, much like a bubbling fluid, provides more effective chemical reactions and heat transfer.
  • FBC technology controls emissions in two ways. First, the fuel is burned at temperatures of 1,400 to 1,700 degrees F, which is well below the threshold where nitrogen oxides form. Second, sulfur dioxide (a priority gaseous pollutant that is generated when sulfur from high sulfur coal or petcoke is burned in the presence of oxygen) is captured inside the combustion chamber by burning the fuel with lime or dolomite. Sulfur dioxide is removed via this reaction: 2CaO + 2 SO2 + O2 = 2CaSO4.
  • The mixing action brings the flue gases into contact with the sulfur-absorbing chemical. More than 95 percent of the sulfur pollutants in coal can be captured inside the boiler using this technology.

Combustion Residue

  • There are two primary residues that remain after petcoke is combusted in a CFB steam generator: calcined limestone residue (commonly known as fly ash) and calcined limestone sand (also known as bed ash).
  • Fly ash is a generic term used to define fine residue that is removed from stack gases using various types of air quality control equipment. However, all fly ash is not equal. Petcoke fly ash is unique because there is virtually no ash from petcoke combustion. The residue that remains after petcoke is burned consists primarily of lime, calcium carbonate, and calcium sulfate.
  • Bed ash is the coarse, solid particulate matter that sinks to the bottom of the fluidized bed combustion chamber and is periodically removed. Petcoke bed ash has a similar chemical composition to fly ash, but is produced in gradations ranging from fine sand to small aggregate.