Thermodynamics Equilibrium Analysis within the Entrained Flow Gasifier Environment

A thermodynamic equilibrium approach is used to calculate the maximum cold gasification efficiency (CGE) of different feedstock within the entrained flow gasifier. The high temperature (1000 to 1500 o K), the small feedstock size (10μm to 0.1mm), and the well mixing environment make them most amenable for equilibrium analysis. Four different feedstock, i.e. RTC coal, pine needles, ply-wood and lignite, are used for the gasification purpose. Using air as oxidizer a parametric study is conducted to show the behavior of CGE and product gasification composition by increasing oxidizer input. A gasification model is developed to calculate the seven unknowns in the gasification product. Using four elemental mass balance and three equilibrium constant relations a mathematical code is developed that also incorporate the solid un-burn carbon in product species. Energy equation is used to calculate the temperature of gasification using iterative approach. Result of model shows that the maximum CGE is achieved when all the solid carbon is converted into the carbon monoxide with nearly all hydrogen present in the feedstock converted into the hydrogen gas. Using this result as baseline, a global model to estimate the maximum CGE is developed in reference to Van Krevelen diagram. This model based on minimum requirement of air to convert all the carbon present in feedstock into carbon monoxide. Result shows a growing trend of CGE with the increase O/C and H/C ratio of feedstock.