The dwindling nature of fossil fuels accompanied by emission concerns is forcing the power sector to find an alternative sustainable option for electricity generation. Using biomass as fuel for electricity generation is one of the most promising options. However, the combustion of biomass often has low thermodynamic efficiency due to the presence of high level of moisture in the raw feedstock. Though removal of moisture before combustion can enhance the cycle efficiency, it is an energy-intensive and expensive process. The main purpose of this research is to investigate how energy efficiency of a biomass power plant can be improved by integrating the drying process to the power generation cycle and properly utilizing process waste heat for feedstock drying.

In this work prior to the in...[ Read more ]

The dwindling nature of fossil fuels accompanied by emission concerns is forcing the power sector to find an alternative sustainable option for electricity generation. Using biomass as fuel for electricity generation is one of the most promising options. However, the combustion of biomass often has low thermodynamic efficiency due to the presence of high level of moisture in the raw feedstock. Though removal of moisture before combustion can enhance the cycle efficiency, it is an energy-intensive and expensive process. The main purpose of this research is to investigate how energy efficiency of a biomass power plant can be improved by integrating the drying process to the power generation cycle and properly utilizing process waste heat for feedstock drying.

In this work prior to the integration study, the drying kinetics of different feedstocks was determined by using general thermo-gravimetric analyses. The drying kinetics was used for predicting the optimum level of drying. Then mathematical models of a steam power plant and dryer were developed. Hot air dryer, super-heated steam dryer and flue gas dryer were considered in the integration studies. Different heat integration schemes were proposed and optimized using the developed models.

Pinch analysis was employed to visualize the intensity of the proposed heat integration and to identify opportunities for improvement. A novel multi-stage drying process was proposed that employs steam and waste-heat from the power plant and the drying process respectively. Results of this study show that with proper drying and heat integration, the overall efficiency of a biomass power plant can be significantly improved.