Development of Gasifier Models for Hydrogen Production Optimization

In this work different gasifiers (entrained flow reactors and dual beds) are modeled with AspenPlus™ according to a procedure which aims at providing useful tools for optimization studies of comprehensive process models. The innovative feature consists in the separation of the steps of solid fuel gasification (devolatilization, oxidation, gasification of the char, homogeneous reactions and tar cracking) and the development of dedicated sub-models (by adapting conventional blocks or implementing structural models as CPD for coal de volatilization). Therefore all steps are connected to respect the material and heat balances according to the gasifier configuration. In this way, the temperature can be related to the operating conditions, i.e. fuel, oxygen and steam flow rates. This aspect is valuable in itself because removes the hypothesis of equilibrium reactors, generally assumed in literature works. Furthermore, the heat balance on the entire reactor allows to quantify the heat recovery, which could be crucial for efficiency calculations of the hydrogen production plant. Also, "by-products" and residual char can be quantified and consequently minimized depending on the operating conditions. Finally, the development of a "gasifier model" instead of a "gasification model" allows different reactor configurations to be compared and optimized. Copyright © 2009, AIDIC Servizi S.r.l.