Plasma-Coated Superheater Tubes – Service Life Increased to at Least 6 Years
In a waste-to-energy plant operating at 40 bar and 400°C, the superheater tubes located after the gas-turning section into the third pass were exposed to flue-gas temperatures of 560–650°C. Under these conditions, tube life was limited to around 18 months.
A sootblower further accelerated wall thinning on the first tube rows. Protective shields were installed but did not deliver any noticeable improvement. As a result, in 2005 a series of trial tubes with plasma coatings (HS 52, 0.8 mm coating thickness) was installed.
The positive in-service experience led, from 2008 onwards, to the replacement of the final superheater banks in all four boilers with plasma-coated tubes, increasing the service life to a minimum of six years.
