Process generalizations and rules of thumb for scaling up biobased processes

Viswanathan, Mothi
Major Professor
D. Raj Raman
Committee Member
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Agricultural and Biosystems Engineering

The premise of the NSF Engineering Research Center for Biorenewable Chemicals (CBiRC) is that a joint fermentative-catalytic process can be exercised to manufacture commodity chemicals from bio-based carbon (e.g., five and six carbon sugar) at prices that are competitive with existing petro-derived chemicals, and with development costs that are far low. Strong technoeconomic analysis (TEA) capabilities exist commercially in tools such as SuperPro Designer® and Aspen Plus®, both of which provide estimations of capital and operating costs. These tools also require a level of detail that is typically unavailable at early stages of process evaluation. To address early – stage TEA, a spreadsheet – based model was developed, named Biorenewables Process Evaluation Tool (BioPET). BioPET served as a prototype for Early Stage Technoeconomic Analysis (ESTEA) tool - a sophisticated process modeling and economic analysis platform for biorefinery processes.

This thesis begins in chapter 2 with reorganizing and expansion of ESTEA. The updated model is given the name ESTEA2. The first part of the chapter describes organization of the model and every unit operation modeling and cost calculations. The latter part describes validation activities related to ESTEA2. ESTEA2 was run with process parameters appropriate to the production of dry-grind ethanol and sorbic acid. The resulting process and cost calculations are compared with estimates from literature, SuperPro Designer® and other third party detailed process models.

In chapter 3 and 4, we use ESTEA2 as a framework to examine the interaction between process and cost parameters. Specifically, computer code was written to explore fermentation parameter-cost-space and the results were analyzed to develop generalizations for titer, productivity and yield limits. Similarly, the impact of downstream unit operation addition to production cost is analyzed using regression analysis. The results in the form of $/kg/Unit Operation addition to upstream fermentation procedure is compute for a wide range of production volume. Later in chapter 4, we compared one – step fermentation process and an integrated fermentation – chemical catalysis method of producing biobased chemicals. We investigated the feasibility of CBiRC’s way of making biobased chemicals by arriving at an intermediate platform chemical through fermentation and then upgrading it to multiple products through chemical catalysis. Finally, chapter 5 summarizes the key findings from this work.