Fire-Side Corrosion of Heat Transfer Surface Materials with Air- and Oxy-coal Combustion

摘要

Tests were performed in a 1.5 MW pilot-scale furnace (L1500) to determine the relative corrosion rates of tube materials typically used in US utility boilers under both air- and oxy-fired conditions. The L1500 was fired with three diverse coals, including: Utah bituminous, Illinois bituminous and North Antelope PRB. Real-time corrosion rates were measured using electrochemical noise (EN) technology. Each of four EN probes had corrosion elements fabricated from SA210 for the water wall probe and P91, 347H and T22 for the three super heater probes. The dependence of corrosion rate on probe surface temperature, local gas stoichiometry and deposition characteristics were investigated. The resulting corrosion data indicated a higher corrosion rate for the superheater materials and a lower corrosion rate for the waterwall materials under oxy-fired conditions. The data also indicated a strong and repeatable dependence of corrosion rate on metal temperature.