(467a) Conceptual Design and Modeling of Entrained Bed Gasifier

With fossil based fuel prices steadily rising as the resources diminishing, renewable energies constitute a very attractive industrial opportunity. Moreover, the implications of the strict environment laws regarding the climate change and greenhouse effect made the power producing companies to look for alternative and cleaner solutions in order to reduce their pollutant gas emissions. Nowadays gasification is a commonly used technology for extracting the energy from coal and solid waste materials as scrap tires or biomass. These materials are gasified producing a gas mainly composed of carbon monoxide and hydrogen which is utilized in gas turbines of Integrated Gasification Combined Cycle (IGCC) systems for power production.

Within the different types of gasifiers, entrained bed reactors achieve the highest gasification rates. These reactors operate with feed and blast (air/steam) in co-current flow with extremely short residence time and high temperatures and pressure. This type of gasifier generates product gas at high temperature and lowest heating value with the highest oxygen consumption.

In this work a model of a entrained bed gasifier unit has been developed for enhanced synthesis gas production. The gasification model is divided into four different stages: drying, devolatilization/pyrolysis, gasification and combustion. The conversion reactions take place sequentially. Numerical simulations are necessary to help in finding out feasible operating conditions to achieve better process performance. The introduction of solids in a process changes the heat and mass balances, even if the solid essentially passes through the process as an inert component. Aspen Plus is chosen as a simulation tool because of its capability on the solids handling. Aspen Plus includes particular physical property model and accurately represents the solid particle. In addition, FORTRAN and MATLAB calculation routines are introduced in the solution procedure. The proposed gasification model improves the understanding of the process and can be used as a predictive tool at the optimization stage.

Financial support received from the European Community projects (MRTN-CT-2004-512233; RFC-CR-04006; INCO-CT-2005-013359) and the Generalitat de Catalunya with the European Social Fund (FI grant) is fully appreciated.