Data: April 25, 2007

EXTENDED ABSTRACT

A technical and economic analysis was performed for a novel biorefinery process which produces acetic acid and ethanol in addition to bleached hardwood pulp.  The acetic acid and ethanol were produced by pre-extraction mixed hardwood chips prior to producing bleach hardwood Kraft pulp using a conventional Kraft fiber line (see Figure 1).  The new process consists of includes hemicellulose extraction, evaporation, hydrolysis, separation, fermentation and distillation and dehydration sections which are used in the production of acetic acid and ethanol. The mass balance and energy balance calculations were performed for the whole process using MathCAD and WinGEMS software. The simulation results were transferred into Excel as output report. Based on the material and energy results from the simulation model, the capital investment and operating cost were determined for the hemicellulose extraction and conversion to ethanol and acetic acid. Capital cost estimates were determined from empirical relationships developed for the different sections of the plant.  The economic viability of the process was assessed by using the discount cash flow rate of return. A comparison was made for the new process relative to the case of producing only bleached hardwood Kraft pulp.  The mass balance and energy balance model of the new process is useful for futuristic research in biorefinery engineering.

Figure 1.  Biorefinery to produce acetic acid and ethanol using the hemicellulose pre-extraction process