Ildefonso Campos Velarde (Dr.)

Fundamentals of Chemical Looping Processes

Introduction

Biomass has become an appealing alternative to decrease the use of fossil fuel in the production of energy. In the ECN Milena process, biomass is converted by the coupling of two separated reactors in order to produce substitute natural gas. Likewise in chemical looping, circulation of bed material is used to transport heat (sand) and oxygen (olivine) from the combustor reactor (bubbling fluidized bed) to the gasifier (riser). In the riser biomass reacts with steam (oxygen), the producer gas is mainly synthesis gas. In a later processing, the gas can be upgraded to produce methane for power generation. The gas produced is nitrogen free, avoiding the NOx production and post processing of the gas to separate it from N2. The unconverted biomass fraction (such as tar and char) and the bed material are circulated back to the combustor where by the aid of air the tar and char are burned to heat up the bed material to the reaction temperature (>800°C). To demonstrate the principle of chemical looping is needed to investigate the catalytic function of bed material (such as olivine) as well as capability to transport heat and oxygen between the two interlinked reactors

Objective

In this project, extensive experimental work is carried out to study the hydrodynamics and reactor performance of chemical looping reactors. A cold-flow pseudo 2D fluidized bed will be constructed to study the effect of external solids circulation in hydrodynamics of fluidized beds. The effect of particle size and density distribution on the residence time distribution will also be studied. Non-invasive technique such as high temperature endoscopic PIV (Particle Image Velocimetry)/DIA (Digital Image Analysis) is applied (see figure) to investigate in detail the effect of temperature and gas production due to chemical reaction in the hydrodynamics of fluidized beds.