Heat exchangers for energy recovery in waste and biomass to energy technologies – I. Energy recovery from flue gas

Energy recovery system of waste-to-energy and/or biomass to energy units represents a substantial part of the whole technology which enables to utilize heat contained in flue gas (off-gas) from incinerators or combustion chambers as much as possible. It is in fact an integrated approach which is illustrated through an example of up-to-date waste-to-energy technology. A simulation system enables to obtain process parameters for thermal and hydraulic design of heat exchangers. It is shown when conventional heat exchangers are used and when there is no other choice than to use tailor-made applications. New types of heat exchangers which were gradually developed are shown. Operational problems like fouling are discussed, and examples of troubleshooting with utilizing computational fluid dynamics as an useful tool are shown as well as a contribution to uniform fluid flow distribution. It is emphasized how understanding of both the process and equipment design is important to be able to speak about a complex and integrated approach.