The Energy research Centre of the Netherlands (ECN) has developed an integrated Bio-SNG production system in past years. Part of this system is the MILENA gasifier. In the MILENA gasifier woody biomass is heated and de-volatilized. Subsequently the volatiles are upgraded to natural gas quality downstream the production line. At this moment ECN has two MILENA gasifiers; a 30 kWth lab-scale installation and a 800 kWth pilot-scale installation. To obtain optimal results, i.e. complete fuel conversion, sufficient residence time of fuel particles in the installation is desired. In view of upscaling the technology, which preferably also implies the feeding of large fuel particles, ECN wondered about the influence of particle size on the carbon conversion. The goal of the research is to investigate this influence. For this purpose a mathematical model is developed which predicts the residence time and resulting carbon conversion of fuel particles within the MILENA gasification reactor.
The model is based on kinetic properties of fuel particles, hydrodynamic behaviour of bed material and hydrodynamic behaviour of fuel particles. The lab-scale as well as the pilot-scale installation have been modelled. The sensitivity of the models on varying modelling parameters is investigated, under which the kinetic properties and dimensions of fuel particles.
For both the lab-scale and pilot-scale MILENA, the research has not led to the indisputable conclusion that the residence time of fuel particles is sufficient to guarantee complete conversion.
Modelling the residence time of fuel particles in the MILENA gasification reactor, Martin Horstink, oktober 2009 (MSc Thesis at the Energy research Centre of the Netherland (ECN)).