Circulating fluidized bed gasification tests of seed cakes residues after oil extraction and comparison with wood

• Sunflower and jatropha seed cakes.
• CFB gasification.
• The fate of inorganic constituents contained in ash.

Cake residues derived from seed crops after oil extraction could be used as fuel to cover a part of heat or power demands of such a procedure. These can be accomplished effectively via thermochemical processing, such as gasification. Contrary to the gasification of woody materials which has been investigated extensively, there is fewer data on gasification applications of residues from newly introduced oil crops after their oil extraction. In this work, seed cake residues of sunflower and Jatropha were gasified.Air gasification tests of these cakes were conducted in a 100 kWth, atmospheric, circulating fluidized bed (CFB). The effect of temperature and bed material on the composition of product gas and tar formation from was compared to willow. Experimental results show that the Carbon Conversion Efficiency (CCE) and cold gas efficiency (CGE) were higher in the case of cakes, especially for sunflower. On the other hand, tar levels were also higher compared to willow. Pilot scale tests were carried out using either olivine and quartz as bed materials. The examination of bed material particles revealed that potassium and calcium derived from the ash accumulated inside the olivine structure, which was not apparent in the case of silica sand where a calcium external layer was observed.Since the biomass ash content and speciation affects the operability of the gasifier, after the end of each trial, fly ash samples from the removal system of particulates, as well as bed ash samples were collected. Various characterization techniques such as X-ray Fluorescence (XRF), Thermogravimetric Analysis (TGA), Ash Fusion Temperature (AFT) and Scanning Electron Microscopy (SEM)/Energy Dispersive X-ray Spectroscopy (EDS) were performed to determine the physicochemical properties of each fuel ash in detail, as well as the fate of inorganic elements initially contained in it.