July 1, 2010

New Process Transforms Waste into Product for Controlling Emissions

By Angela Neville, JD

In April, Solvay Chemicals Inc. commissioned a new facility that uses an innovative process to recover and transform sodium carbonate waste streams into a market-grade sodium bicarbonate used in air emissions control. Located in Green River, Wyo., the plant reclaims the sodium carbonate waste produced by Solvay’s nearby soda ash plant, which would otherwise be shipped to a detention pond, and creates a new product, SOLVAir Select 300. Once processed, this product can be used at coal-fired power plants and biomass waste-to-energy facilities to cut sulfur dioxide (SO₂), hydrochloric acid (HCl), and other acid gas emissions (Figure 4).

4. Two-for-one environmental benefits. The SOLVAir Select 300 Plant in Green River, Wyo., reclaims and transforms sodium carbonate waste streams into a marketable grade of sodium bicarbonate that can be used for cutting SO2, HCl, and other acid gas emissions at coal-fired power plants and biomass waste-to-energy facilities. Courtesy: Solvay Chemicals Inc.

POWER asked several representatives in May to explain the process used at the new plant. David Hansen, senior project engineer, gave an overview of how the sodium carbonate reclamation process works.

“A sodium carbonate–rich waste stream must be purged from the soda ash plant at Green River to maintain purity levels in the final soda ash product,” Hansen said. “This waste stream normally is disposed of in surface detention tailings ponds. However, as part of the S300 process, this waste stream is reacted with carbon dioxide to form sodium bicarbonate in a vessel called a crystallizer. The crystalline sodium bicarbonate is removed from the reacted waste stream by a series of cyclones and centrifuges and then dried to produce the final product.”