Most Typical Failures in Kraft Recovery Boilers - A Statistical Approach

摘要

The basic principles of the Tomlinson recovery boiler are still mainly valid. However, the size and energy efficiency of Kraft recovery boilers have been increased significantly. The construction of the recovery boiler has been systematically developed during the years. The goal has been to improve the safety and availability of recovery boilers. In addition, energy efficiency and pressures to lower the emissions have affected the design. However, the biggest driver to the construction and design has been the growth of the physical size of the recovery boiler furnace. A 3000 tds/d recovery boiler was regarded as huge 25 years ago and it was believed that they cannot grow any bigger. This shows that sometimes predictions do not predict anything. Along with the growth of the furnace size, the length of heat transfer surfaces has increased, especially on the economizer and superheater sections. Increasing heat loads set also special requirements to the construction and design of recovery boilers. This paper presents a summary of the most frequent failure types in recovery boilers since 1990s according to records from the Finnish Recovery Boiler Committee (FRBC), Sodahuskommitten (Sweden) and Black Liquor Recovery Boiler Advisory Committee (BLRBAC). From the statistics it is possible to draw conclusions about the most frequent failure types and how these have been changing during the years.