Simulation und Optimierung von Herstellungsverfahren für Biobutanol der zweien Generation

Abstract

A promising process design for butanol fuel production using lignocellulosic biomass through thermochemical route has been carried out and developed. The process design is based on an extensive literature survey and analysis for the potentials of variable feedstocks including energy crops as well as residual and waste materials of biomass, possible production routes and the state of corresponding technologies. The designed process is simulated using Aspen Plus and consists of the following 5 major steps: biomass drying, autothermal gasification with entrained flow gasifier, gas cleanup and conditioning, higher alcohol synthesis over a modified methanol catalyst and alcohol separation. To enhance the product yields, a portion of the generated methane and other hydrocarbons is reformed through autothermal reforming to produce additional syngas and recycled together with unreacted syngas. Through the process optimization, a final product yield of 6232.5 kg/h of butanol fuel is obtained, which contains 88.2 wt.% of isobutanol and 10.7 wt.% of propanol. A heat integration based on pinch analysis is carried out and an optimized heat exchanger network has been developed, resulting in an energy-efficient process which requires no external hot utilities and only small part of power from grid. An overall plant efficiency of 60.9 % is achieved. Based on the simulation results from Aspen Plus, an economic evaluation is carried out to estimate the net production costs of butanol fuel, which turns out to have a specific net production cost of 2.25 €/L. Still the NPC is much higher than the acceptable market fuel price. A sensitivity analysis is conducted, finding out that the variation of investment cost of entrained flow gasifier, cost of raw biomass and cost of maintenance labor has the most significant impact on the net production costs. The expected future targets in terms of technology development, simulation improvement as well as costs reduction potentials are briefly discussed at the end of this thesis.