Deposition and high temperature corrosion in a 10 MW straw fired boiler

摘要

Deposition and corrosion measurements were conducted at a 10 MW wheat straw fired stoker boiler used for combined power and heat production. The plant experiences major problems with deposits on the heat transfer surfaces, and test probes have shown enhanced corrosion due to selective corrosion for metal temperatures above 520 deg. C. Deposition measurements carried out at a position equal to the secondary superheater showed deposits rich in potassium and chlorine and to a lesser extent in silicon, calcium, and sulfur. Potassium and chlorine make up 40-80 wt./100 of the deposits. Mechanisms of deposit formation and selective corrosion are discussed based on the results of the practical measurements.