Two Fluid Model using Kinetic Theory for Modeling of One-Step Hydrogen Production Gasifier

A Two Fluid Model (TFM) using kinetic theory of granular flow has been developed to describe an innovative process of hydrogen production in a single step. An extended Multi-species of Solid Phase (MSP) method is proposed to simulate the gas-solid heterogeneous reactions in an entrained flow gasifier, as opposed to Single-species of Solid Phase (SSP) in previous studies. The intrinsic equations of methane steam reforming and water-gas shift reactions are used for a good understanding of the reaction mechanism for high concentration of hydrogen production under higher pressure. On the basis of the results of computing, the main feature of core-annular reaction zone is predicted in the fully developed flow region. And the similar flame-like structure for velocity and temperature is observed to emerge from the feed injection zone at the bottom of gasifier. The model well illustrates the effects of CaO on enhancing the concentration of hydrogen and sequestering CO2 in the process of coal gasification. The advantages of pressure gasification are also shown that coal conversion increases with increasing pressure while H2S concentration and tar content decreases. Moreover, there is a steep increase in H2S and tar species initiated from the entrance of gasifier and then a decrease at the next section. The model,shows good agreement with the measurements of flow field and gas products concentration in laboratory-scale plants. (C) 2008 American Institute of Chemical Engineers AIChE J, 54: 2833-2851, 2008