Ocean Disposal of Consolidated Spray Dryer Flue Gas Desulfurization Wastes

Abstract

Combustion of coal in electric power generating stations results in the production of large quantities of fly ash and flue gas desulfurization end products. These wastes must be disposed of by environmentally acceptable means. Ocean disposal of these wastes is an attractive option for power stations located on coastal waterways. Dumping of fly ash and untreated wet FGD sludge is environmentally deleterious. However, wet scrubber sludge stabilized with fly ash can be formed into solid dense blocks which have been shown to be acceptable for ocean disposal. The Marine Sciences Research Center has been investigating this disposal option for the past five years. A new FGD technology, Spray Drying Absorption, was introduced about five years ago. This process produces a dry end product composed of fly ash, desulfurization reaction products and excess reagents. When lime is the reagent the end products can be dampened and consolidated into self-hardening dense blocks. Niro Atomizer has been investigating dry FGD end product disposal and utilization for the past three years. An assessment of the feasibility of using solid blocks formed from dry FGD end products for ocean reef construction is being performed by the Marine Sciences Research Center. Consolidated dry FGD end products from Niro Atomizer's Riverside dry FGD demonstration facility and Copenhagen dry FGD pilot plants were tested. These wastes represent low sulfur western and European coal applications. The end products were dampened and consolidated into Proctor cylinders. After curing, the cylinders were exposed in sea water systems including the open seas for up to 6 months. Block structural integrity was maintained during this period and porosity remained essentually unchanged. The unconf ined compressive strength remained high during the test period.