Agglomeration problems during cardoon fluidized bed gasification

Abstract

Cynara Cardunculus, commonly known as cardoon is a potential energy crop native to the Mediterranean region with high production yields reported. The aim of this work is to present an overview on the contradicting agronomic data available for cardoon and its potential exploitation in industrial thermochemical (i. e. combustion and gasification) applications. Moreover, experimental work on cardoon gasification is presented, focusing on the agglomeration problems it causes when using it in fluidized bed gasifiers. Cardoon cultivated in Greece was gasified in a100 kW thermal atmospheric circulating fluidized bed gasifier. Due to high ash content (rich in potassium) defluidization was observed at low temperatures (780 °C) during the first 30 minutes after the fuel feeding begun.The agglomerates are investigated with SEM/EDS in an effort to determine the gluing mechanism. The particular cardoon was rich in calcium, and this was apparent in the rich in silicates re-solidified melt.