(173ap) High-Temperature Corrosion in Waste-to-Energy (WtE) Boilers and Cement Kiln

The combustion of the municipal solid waste in waste to energy plants leads to the formation of different types of chlorine and sulfur compounds which leads to corrosion on the surface of the boilers. Boiler corrosion is a crucial problem that leads to occasional shutdown of the plant which in turn increases the operating cost of the plant. Thus, to minimize boiler corrosion, we focus on studying the role of such compounds by carrying out laboratory tests using different boiler materials used in the industry. The laboratory tests are done to study the mass loss and corrosion rates of the materials when exposed to different environments and to select a material that can minimize corrosion in WtE plants.

For the WtE corrosion tests, Ni-based alloys with different compositions are used, and in cement kiln tests Fe-Cr-Ni-based alloys with various compositions are used. The results expected from these tests are that the mass loss in the Ni-based alloys and Fe-Cr-Ni-based alloys is decreased due to the formation of a more protective and passive oxide layer. The formation of such an oxide layer can minimize corrosion of boilers.

Three different boiler materials are used to study the high-temperature corrosion in WtE plant boilers and cement kilns. The materials used for the WtE experiments are Colmonoy 494 (0.42%C, 29.5%Cr, 3.48%Si, 1.2%Fe, 2.35%B, 58.2%Ni, 0.02%W, 0.01%Co, and 4.79%Mo), SP99 (0.76%C, 14.5%Cr, 3.53%Si, 13.8%W, 3.48%B, 1%Mo, 0.016%Co, 4.8%Fe and 54.2%Ni), SP686 (0.24%C, 8.9%Si, 22.1%Cr, 59.2%Ni, 7.26%W, 0.912%B, 0.014%Co, 2.8%Fe, and 5.57%Mo). The experimental materials used for the cement kiln tests are labeled as J (58%Fe, 25%Cr, 13%Ni, 1%Al, 1.2%Mn, and 1.1%Si), P (60.9%Fe, 22.6%Cr, 4.3%Ni, 0.5%Al, 10.4%Mn, and 1.3%Si) and F (63.9%Fe, 26.1%Cr, 5.5%Ni, 0.9%Al, 1.9%Mn, and 1.7%Si). The temperature range for these tests is between 400°C to 1000°C. The gas mixture used for the test is the WtE flue gas mixture and the cement kiln test is carried out in the oxidizing environment which includes CO₂ (15%), O₂ (5%), H₂O (10%), and N₂ (70%). These tests are conducted for 100-200 hours.

This presentation will show comparative results for several conditions and discuss possible reaction sequences leading to the observed corrosion rates.