(403b) High Temperature Corrosion of Commercial Alloys At Various SO2/HCl Ratios

Waste-to-Energy (WTE) plants generate nearly 3.0 gigawatts of electricity in the United States annually via the combustion of about 28 million tons of municipal solid wastes (MSW). Several of the major operating problems facing these facilities (low efficiency, plant shutdowns and high capital costs) are a result of high temperature corrosion that occurs on boiler surfaces. With increasing steam temperature, unprotected metals that constitute the evaporator and superheater are subject to a series of reactions caused by the presence of hydrogen chloride (HCl) and sulfur dioxde (SO₂) in an oxidizing environment. The mechanisms thought to explain HCl and SO₂ corrosion can be complex, involving multiple gas phase and gas-metal surface reactions. Despite its corrosive nature, some studies have suggested that SO₂ can have a beneficial effect within certain concentrations. In the following presentation, the corrosion mechanisms of multiple commercial alloys are examined via lab scale corrosion furnace tests, simulating typical WTE conditions at various SO₂/HCl ratios.