Laser-based deposit diagnostic in biomass-fired power plants

Abstract

Several components in biomass and waste such as alkali metals result in combustion residues. Part of them form deposits on the walls of superheaters and water walls, leading to corrosion and lower heat output. These deposits are to be removed during operation of the power plant. An adjusted cleaning of the deposits improves the plant’s efficiency by increased heat output or enables a higher throughput and leads to reduced maintenance costs. Both the deposit location and the deposit properties affect the efficiency of the cleaning. Thus, measurement setups aim to detect the deposits online and to analyze their properties. Laser-based diagnostic comprises the detection of deposits and their thickness by measuring wall distances. The system can be used as stand-alone setup or in combination with different measurement setups as well as in combination with balancing tools to predict deposit development of large heat exchanger areas. The established measurement setup is presented followed by the integration of the system into modern monitoring systems. Afterwards, results are presented that were recorded during a measurement campaign at a German waste power plant. The results are applicable to biomass fired power plants. As part of the study several measurement setups were installed and compared. Topology plots recorded with the laser distance sensor and an assessment of their usefulness regarding cleaning optimization follow, both as single measurement setup and as part of a monitoring concept.