Techno-economic analysis of the integration of flue gas dryer and steam-air preheater into biomass power plant

Abstract

For a biomass power plant, which uses a biomass fuel having a high moisture content, flue gas drying is an effective method of increasing the overall power plant efficiency. However, this method requires flue gas that has a high temperature. Most biomass power plants, however, are designed so that flue gas temperature is already reduced to a low value through the installation of economizer and air heater. This paper investigates the use of steam-air preheater to raise both air temperature and flue gas temperature. Therefore, steam-air preheater enhances the potential of flue gas dryer, and both devices can be used in conjunction to raise the overall efficiency of a biomass power plant. Models of power plant, flue gas dryer, and steam-air preheater are used in this paper to demonstrate by simulation that the integration of flue gas dryer and steam-air preheater results in 2.52% increase in electrical power output of a reference power plant that consumes a fuel with 52% moisture content (wet-basis) if the fuel moisture removal rate in flue gas dryer is 7140 kg/h, and the total heating surface area of steam-air preheater is 2000 m2. The simple payback period for the investment in this integration is 3.3 years.