Recovery of Volatile Products from Dilute High-Fouling Process Streams

Abstract

As biomass hydrolysis and fermentation technologies approach commercial viability, advancements in product recovery technologies will be required. For cases in which fermentation products are more volatile than water, recovery by distillation is often the technology of choice. Distillation technologies that will allow the economic recovery of dilute volatile products from streams containing a variety of impurities have been developed and commercially demonstrated. Distillation tower and tray designs, along with specialized heat-exchanger designs, allowing for extended processing intervals on solutions containing lignocellulosic residues, organic acids, and inorganic salts concentrations > 100 g/L are in commercial operation. In the case of ethanol, distillation energy consumption efficiencies for processing solutions containing < 40 g/L of desired product can approach demonstrated energy consumption efficiencies for solutions containing concentrations > 120 g/L. These proprietary technologies have been applied individually at commercial scale, and designs have been developed that incorporate the combined technologies with only a marginal increase in capital investment compared to traditional methods.

Reducing the Energy Demand of Cellulosic Ethanol through Salt Extractive Distillation Enabled by Electrodialysis

“…However, there is a drastic increase in the distillation energy demand as the ethanol concentration in the fermentation broth from cellulosic sources is relatively low (30,(37)(38)(39).…”

Influence of fermentation by-products on the purification of ethanol from water using pervaporation

“…These include batch-operation of the fermentor, low glucose-to-ethanol yield and no reuse of salts and microorganisms (Nomura et al, 2002). Moreover, energy requirements increase exponentially when ethanol concentration in the feed solution fall below 5 wt.% (Madson and Lococo, 2000). Hence, a lot of research was carried out in finding energetically more attractive separation techniques, such as gas/steam stripping (Ezeji et al, 2004), liquidliquid extraction (Bothun et al, 2002), adsorption (Carton et al, 1998) and pervaporation (Bowen et al, 2007;Fadeev et al, 2003;Ikegami et al, 2003;Nomura et al, 2002).…”

Review of Second-Generation Bioethanol Production from Residual Biomass

“…Distillation enables the recovery of dilute volatile products, such as ethanol, from impure biomass-based streams (83). Residual solids, such as unconverted polysaccharides (cellulose, hemicellulose), ash and compounds from the breaking down of lignin, contaminate these streams (83).…”