In this project, simulation of fluidized bed gasification will be conducted. The work is a part of EU-Funded Bio-FlexGen project, which has 14 partners involved across the EU. The large EU project aims for developing a highly-flexible CHP process that can generate electricity and heat from biomass , with a much higher electricity efficiency, in the winter time, and produce green hydrogen in the summer time, to follow the seasonal demand changes. Bio-FlexGen will develop an optimised combination of biomass and green hydrogen for combined heat and power plants (CHP), playing a major role in the energy system integration. In this simulation project, the work will consist of two parts, with the first one focusing on solid particles flow in a standpipe of a fluidized bed system, and the second one on the simulation of a pressurized fluidized bed gasifier at KTH. The research work will deepen understanding of multi-phase flows and reactions in a pressurized biomass fluidized bed gasifier and bridge knowledge gaps in the pressurized fluidized bed gasification field.