Wheat straw and pig manure gasification in a drop tube furnace

Due to greenhouse gas emissions and the consequent damage caused by global warming due to the use of fossil energy sources, the conversion of biomass to fuel has gained special attention. Biomass gasification can produce high quality syngas and solid by-products. The effect of the addition of steam and carbon dioxide in biomass gasification in a drop tube furnace (DTF) is reported in this project. Pig manure and wheat straw particles, ranging from 90 to 150 μm were the biomass used. The biomass feeding rate was fixed at 30 g/h and oxygen was fed to the reactor at a constant excess air ratio of 0.4. In wheat straw gasification, the influence of steam/biomass (S/B) ratio at 1000 oC was examined while in pig manure gasification, the gasification atmosphere and temperature were the variables investigated. Pig manure gasification was performed in mixtures of nitrogen/oxygen, nitrogen/oxygen/steam and nitrogen/oxygen/carbon dioxide for distinct DTF wall temperatures between 900 and 1200 oC. The results show that soot and char decrease, increasing the S/B ratio in wheat straw gasification. The syngas lower heating value, the carbon conversion efficiency and the cold gas efficiency were higher at S/B = 0.8, while at S/B = 1.7 the hydrogen/carbon monoxide ratio was higher. In pig manure gasification, the quantity of char particles was lower in the mixture nitrogen/oxygen/carbon dioxide for all temperatures investigated while for 1100 and 1200 oC the quantity of soot particles was lower in the mixture of nitrogen/oxygen/steam. In this case, the syngas lower heating value and the cold gas efficiency were higher for the atmosphere with carbon dioxide while the carbon conversion efficiency and the hydrogen/carbon monoxide ratio were higher for an atmosphere with addition of steam.