Corrosion and Deposits from Combustion of Solid Waste—Part VII: Coincineration of Refuse and Sewage Sludge

Abstract

Corrosion probe exposures were conducted in the Harrisburg, Pennsylvania, incinerator to determine the effects of burning low-chloride sewage sludge with municipal refuse. Probes having controlled temperature gradients were used to measure corrosion rates for exposure times up to 816 hours. The effects of exposure time, metal temperature, and gas temperature were studied. The results demonstrated that the addition of the sludge reduced the initial corrosion rates of carbon and low-alloy steels to about half that from refuse alone. Little effect was observed on the rates for Types 310 and 347 stainless steels. An aluminized coating on steel resisted corrosion effectively and offers promise as a cost-effective substitute for expensive alloys. In the range 500–900° F the corrosion rates of carbon steel and T22 increased with temperature while those for the stainless steels decreased. Reducing the flue gas temperature from 1500° F to 1100° F reduced corrosion rates significantly and made them less dependent on metal temperature. The addition of low-chloride sludge to refuse is recommended as a corrosion prevention measure and a waste disposal technique.