Development of Experimental Systems and Modelling Tools for studying Biomass Gasification

This Thesis deals with experimental systems and modelling toos which can aid the development of biomass gasification. Recognizing the complexity of the topic, a methodology that integrates modelling and experimental activities is applied both to laboratory and pilot scale studies. This Thesis is linked to newly born CRIBE (a research centre devoted to the study of energy biomass), dealing with the development, setup and testing of the pyrolysis and gasification units installed in the centre. The first part of the work was focused on the phenomena involved in biomass gasification, in particular biomass devolatilization. A procedure for the evaluation of high heating rate biomass devolatilization kinetics was developed, integrating the experimental campaign on a Drop Tube Reactor with a modelling activity of this laboratory device by means of a CFD code. The study of biomass pyrolysis was further carried out at CRIBE. An experimental campaign on a batch pyrolysis reactor was carried out both to test the capabilities of a tar sampling system and asses a tar characterization methodology which integrates different laboratory techniques (from TG-FTIR to GC-MS). These activities provided the basis for the following phase, which focused on the study and characterization of a pilot scale gasification plant. This activity was carried out integrating an experimental campaign and a modelling study. The first was focused on the setup of process measurements and samplings on the gasification facility as well as testing pelletized biomass as feedstock in a pilot scale downdraft gasifier. This activity allowed to evaluate the most important parameters as well as the performance of the gasification process, and suggested possible improvements to the test rig. The latter was aimed to develop an interpretative tool of the gasifier behaviour. This activity was carried by means of the commercial code gPROMS and based on a 1-D representation of the gasifier.