Alternative Process Technologies for High-Water Applications

Session Chairs:

• Keith Hutchenson, DuPont

Session Description:

Many “sustainable” chemical manufacturing operations involve processing of aqueous mixtures, which provides unique chemical engineering challenges compared to more traditional petrochemical-based processes.  For example, traditional downstream separation processes such as distillation and evaporation exist to remove various products from these aqueous mixtures, but such thermal processing of dilute aqueous solutions requires large energy inputs, which negatively impacts the process economics and sustainability.  This session will feature talks describing alternative processing approaches to consider for more efficiently addressing process development with dilute aqueous streams.

Schedule:

Abstracts:

Liquid-Liquid Extraction for Recovery of Chemicals from Dilute Aqueous Streams

Donald Glatz, Koch Modular Process Systems

Liquid-liquid extraction (LLE) can often be applied to separation problems involving the removal of chemicals from dilute aqueous streams, especially when these chemicals are higher boiling than water.  The cost to boil water can be prohibitive for systems with low concentrations of high boiling components.  However, when the proper solvent and equipment is selected, economical solutions can be developed for extracting and recovering these chemicals.  This presentation will outline where, when and how LLE can be applied to these types of separation problems.  It will look at the basic steps towards implementation of an extraction process.  The first step is solvent selection and generating liquid-liquid equilibrium data.  This data can be used to make a preliminary design for the production equipment and also to determine the economic feasibility of the extraction process.  If it is economically feasible, then pilot plant testing is performed to generate accurate scale-up data.  Finally, the test data is used to design of the production extraction equipment.  Several examples will be presented, including pilot plant data and subsequent scale up to production size equipment.

Design and Optimization of Recovery and Purification Processes for Bio-based Materials

Erik Gommeren, DuPont

Processing of food and bio-based products presents unique challenges as the target (product) molecules are typically present in low concentrations in a complex fermentation broth or plant-based feed stock. These product molecules often have limited stability due to sensitive to heat, shear, and oxidation. They need to be recovered, purified, and concentrated from a water based process stream, before they are formulated into a high purity dry product form. This means that food and biotech operations are very separation intensive (30-70% of operating cost) and tend to have a large water footprint with large quantities of waste water produced per kg of product.

Mechanical Separation Technologies such as centrifugation, and filtration are often more energy efficient compared to thermal separation processes, and cause fewer issues with product stability due to milder processing conditions. Separation equipment is constantly evolving as new separation concepts are invented, existing designs are improved, and capital cost is coming down. This opens up new applications in food and biotech that were previously considered not feasible.

Selecting the right separation method and using state-of-the-art technologies will be critical for the long term competitiveness and sustainability of food and biotech businesses.

In this talk I will give an overview of the particular separation challenges in the biotech and food  industry, and discuss methodologies for equipment selection, process scale-up and optimization .

Fundamentals of 'Gas-Assisted' Separations for Dilute Aqueous Systems

Aaron M. Scurto, University of Kansas

The separation of dilute aqueous systems is a reoccurring challenge within industry, especially for processes with biomass or bio-renewable based feedstocks.  Many processes involve energy-intensive separations such as distillation, liquid-liquid extraction followed by distillation, etc. which significantly affects costs and sustainability.  As a potential alternative to thermal-based approaches, we introduce a method called “Gas-Assisted” Separations.  Here, a gas is dissolved into the aqueous solution to induce the target solute from the aqueous phase into a new phase (liquid or solid) rich in that target solute.  The systems can be decanted/filtered to recover the solute and the gas can be recovered with depressurization.  These processes differ from supercritical fluid technology where the compressed gas/fluid is the solvent itself and require much higher pressures.  This “salting-out” with an easily recoverable dissolved gas “antisolvent” (versus a solid salt or liquid, etc.), may have very different molecular mechanisms for each gas and solute combination.  For instance, the use of gaseous CO₂ would lead to both a decrease in pH and increase in the ionic strength which may have specific interactions with a given solute.  In this presentation, the fundamental phase equilibrium will be overviewed for this vapor-liquid-liquid equilibrium (VLLE) behavior with temperature, pressure, and initial loading.  Examples from literature will be used to illustrate the process.