Simulation and optimization of the Syngas fermentation to ethanol with cell recycling

The gasification of biomass followed by fermentation can be one an alternative to meet fuel demand in the future. Gasification of biomass produces a gas rich in CO and H₂ known as  syngas, which are essential components for  subsequent ethanol production. The syngas fermentation process offers, potentially, several advantages when compared to chemical routes as a high specificity of biocatalysts, lower energy costs and does not require of a fixed ratio of CO:H₂.  Relatively few works focused on the simulation of this process are found in the literature. With a suitable simulation platform to represent the main phenomena taking place in the process is possible to understand the process behavior as well as to investigate several scenarios in such way to evaluate if this technology is feasible in terms of costs and operating conditions. In order to carry out this investigation it will be evaluated the impact the syngas fermentation process variables on the ethanol production yield.

Bearing all this in mind, this work presents a simulation, validation and optimization of the syngas fermentation process using Aspen Plus^TM simulator. Syngas compositions used in these simulations are from experimental data generated in the gasification of the sugarcane bagasse. The influence of operating conditions as fermenter temperature, syngas composition, initial total pressures of syngas and impurities in the syngas as methane and traces of NO were investigated for the production of ethanol. The simulation of proposed syngas fermentation process with cell recycling presents good results according to the validation with experimental data.