Experimental investigation on the air gasification of olive cake at low temperatures

In this work, the impacts of temperature, equivalence ratio, contact-time, and torrefaction on air gasification of olive cake at low temperatures were experimentally investigated. Both raw and hydrolysed olive cake feedstocks were considered. The yields of main fuel gas products, the gas LHV, and cold gas efficiency (CGE) were adopted as the indicators to evaluate the gasification performance. The experimental work was conducted in fixed bed reactor. Higher CO, CH4 and H2 yields and CGE were obtained for an equivalence ratio of 0.3 and a temperature of 700 °C. The main difference between gasification of raw and hydrolysed olive cake samples were the higher yields of fuel gas in hydrolysed sample, likely due to the higher lignin content. The main difference between non-torrefied and torrefied samples was observed on CO and CH4 yields and CGE. At the same operating conditions, the CO and CH4 yields increased with torrefaction, while H2 yield decreased. Gasification of torrefied-raw olive cake increased by 14.1% and 95.3% the CO and CH4 yields. Finally, important differences on results were found when metal-loaded samples were tested. This study demonstrated that both hydrolysed and raw olive cake samples are high quality gasification feedstock to achieve a good CGE also at relatively low gasification temperatures.