Kinetic modeling and simulation of throated downdraft gasifier

• This is the first realistic kinetic and transport model for the throated gasifiers.
• Air is introduced just above the throat of the imbert design.
• Air flow is estimated using the pressure for the fixed bed gasifier operated with vacuum pump.
• Product gases exiting the reactor and passing thorough the jacket is also considered.
• To understand transient behaviors of gasifier, energy of inner wall is also modeled.

An imbert ‘throated’ gasifier which has hourglass heart and varying axial area and nozzles for injection of gasification agents has been studied. The transport of reacting gas-solid two-phase mixture through the gasifier has been mathematically modeled transiently. Downdraft gasification in such a complex system has so many variables and is quite cumbersome to describe. For the first time throated gasifiers are modeled as realistically as possible. The resulting set of transport, structural, kinetic and auxiliary equations was solved via numerical methods. The modeling work was experimentally validated using a 10 kW gasifier. The actual geometry of the experimental setup was used in the model. The model results were in line with the experimental results. Throated combustion zone causes better distribution of heat and reduces heat loss. With the same core size and solid consumption, stratified gasifier output was 24.5% less than throated one. The model exit had 25.85% CO; 18.25% H2; 7.84% CO2; 2.9% CH4; while the experiment had 35.07–20.77% CO; 18.30–13.66% H2; 13.68–5.95% CO2; 6.7–1.2% CH4; the rest was N2. The model can be applied to different geometries.