Modeling, Simulation and Control of Fixed-bed Downdraft Biomass Gasifier

Abstract

The demand of energy, electricity and fuel, has been consistently increasing world over and more so in emerging countries like China, India, Brazil, etc. Major source of energy has been fossil fuel even today and will remain in future. However, recently concerns against use of fossil fuels are increasing due to reasons like fast-depletion of fossil-fuel resources, its adverse environmental effects causing global warming, etc. Hence, globally researchers have been exploring alternate, sustainable, renewable energy sources like solar, wind, mini-hydro, biomass, tidal etc. Amongst these, biomass is of our interest due to its specific advantage, i.e. better source-side (biomass-feed side) control allowing flexing of the source-side energy, which is not possible for other popular renewable energy sources e.g. solar, wind. Hence, modeling and simulation of physical real-world systems is important to understand and analyse the system behaviour to help system design and operational controls. This project involve the mathematical modeling, simulation and validation of downdraft biomass gasifier a renewable energy source. Biomass gasification is a promising processing route to convert the energy embedded in biomass. This study contain overview of biomass gasification, biomass feedstock, different types of biomass gasifiers and study of open top downdraft IISc gasifier. A comprehensive literature survey has been carried out to collect the data specific to steady state modeling of downdraft biomass gasifier. The different parametric studies on downdraft biomass gasifier like effect of moisture content, oxygen factor, temperature and calculation of calorific value is performed. The output gas composition values validate with reference model data and experimental data from literature. Additionally actual gasifier setup in our laboratory is used for validation and the results are in agreement. Controller study is performed to investigate servo and regulatory performance. Biomass gasifier simulation framework is developed in matlab.