Ethanol processes

Singh, V., Moreau, R.A., Doner, L.W., Eckhoff, S.R., and Hicks, K.B. 1999b. Recovery of fiber in the com dry-grind ethanol process A feedstock for valuable co-products. Cereal Chem. 76, 868-872. 

NREL (National Renewable Energy Laboratory). Lignocellulosic biomass to ethanol process design and economics utilizing co-current dilute add prehydrolysis and enzymatic hydrolysis for com stover. Golden, CO US (2002). Report available on web http //www.mel.gov/ docs/ fy02osti/32438.pdf... 

Lignocellulosic Biomass to Ethanol Process Design and Economics Utilizing Co-Current... 

Although ASPEN-Plus is widely used to simulate petrochemical processes, its uses for modeling biomass processes are limited owing to the limited availability of physical properties that best describe biomass components such as cellulose, xylan, and lignin. For example, Lynd et al. (1) used conventional methods to calculate the economic viability of a biom-ass-to-ethanol process. However, with the development by the National Renewable Energy Laboratory (NREL) of an ASPEN-Plus physical property database for biofuels components, modified versions of ASPEN-Plus software can now be used to model biomass processes (2). Wooley et al. (3) used ASPEN-Plus simulation software to calculate equipment and energy costs for an entire biomass-to-ethanol process that made use of dilute-H2S04 acid pretreatment. 

Fig. 1. Process flow diagram for typical dry-grind ethanol process.

Stuart, D.L. and Wills, R.B.H. 2000b. Factors affecting the extraction of alkylamides and cichoric acid during ethanolic processing of Echinacea purpurea (L.) Moench. Aust. J. Exp. Agric. 40, 873 -877. 

For the purpose of conceptual design of the bioethanol plant, Aspen Plus will be used as the flowsheet simulator. However, most of the key components involved in the process are not defined in the standard Aspen Plus property databases, and therefore their physical property data are not available. The National Renewable Energy Laboratory (NREL) has developed a database that includes a complete set of properties for the currently identifiable compounds in the ethanol process [28]. 

Rychtera, M., Barta, J., Fiecter, A., and Einsele, A. A. (1977). Several aspects of the yeast cultivation on sulphite waste liquors and synthetic ethanol. Process Biochem. 12(2), 26-30. Rydholm, S. A. (1965). "Pulping Processes." Wiley (Interscience), New York. 

Aden, A., Ruth, M., Ibsen, K., Jechura, J., Neeves, K., et al., Lignocellulosic Biomass to Ethanol Process Design and Economics Utilizing Co-Current Dilute Acid Prehydrolysis and Enzymatic Hydrolysis for Corn Stover NREL Report No. TP-510-32438 available online at URL http //www.nrel.gov/publications/ National Renewable Energy Laboratory Golden, CO, June, 2002, 2002 p. 154. 

Emptage listed DuPont s guiding principles for cellu-losic ethanol process development ... 

The next phase in the development of advanced fermentation ethanol processes concerns the conversion to ethanol of all the pentose and hexose sugars released on hydrolysis of lignocellulosics. Traditional bakers yeast strains promote fermentation of hexoses at high yields, but over long periods of time, and they do not ferment the pentoses. Although some yeasts use both hexose and pentose sugars as sources of carbon and energy and ferment hexoses and xylose, they do not ferment arabinose and the other pentoses. The overall stoichiometry of hemicellulose hydrolysis and pentose fermentation is... 

Figure 5.14 shows an ethanol process. The last unit is a distillation tower to remove water from a mixture of water and ethanol. Note that the mixture forms an azeotrope. The feed stream is 100 lb mol/h of a 50-50 molar mixture of water and ethanol at 80 F and 1 atm. 

Simulate the ethanol process (Problem 5.6) using Aspen Plus. The feed streams are at 1 atm and room temperature, but the reactor operates at 960 psia and 570°F. Thus, you must heat the reactor feed, and after the reaction occurs you must cool the product. The first splitter is a vapor-liquid separator (you choose the temperature that will separate ethanol from ethylene), and the remaining splitters are distillation columns. You will have to decide on the number of stages and reflux ratio using DSTWU first might be useful. 

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