The recovery of blowdown heat using steam dryer in biomass power plant

Abstract

The main objective of this paper is to propose the blowdown heat recovery system using a steam dryer. A flash tank is used to reduce blowdown water pressure and generate flash steam. Flash steam is supplied to the steam dryer to decrease fuel moisture content. Exhaust vapor vented from the steam dryer is also used to increase air temperature in an air heater. Furthermore, due to decreased fuel moisture content and increased air temperature, the exhaust flue gas temperature may be decreased by increasing the air heater surface area in the boiler. This method of blowdown heat recovery has never been proposed before. Therefore, it may be considered as knowledge gap that is worth an investigation. The use of blowdown heat for steam drying is compared with the use of blowdown heat for feed water heating. Simulation results show that using blowdown heat for steam drying results in a significantly larger net power output. Furthermore, the integration of this heat recovery system is economically feasible.