(176f) Optimal Design, Operation, and Scheduling of Biodiesel Production

With the emphasis on biofuels research and their widespread adoption as alternative fuels, biodiesel is attracting much attention as a promising supplement to fossil fuels. To address limitations and uncertainties in the availability of biomass, future biodiesel plants should consider operations involving multiple feedstocks. Utilizing one biomass feedstock has its supply limitations and ties the production plant into the fluctuating availability and cost of the biomass. This paper is aimed at developing a systematic procedure for the design along with the associated scheduling and operating schemes for a biodiesel plant which employs multiple feedstocks. This task involves concerted activities in process synthesis, simulation, design, operation, integration, optimization, and profitability. The problem may be formally stated as follows:

Given a certain desired production rate of biodiesel and a number of feedstock alternatives along with their reaction and cost data, it is desired to design a cost-effective plant which can operate using co-fed or segregated feedstocks. It is also desired to develop an optimum process design and to determine the optimum scheduling and operating strategies.

The abovementioned problem involves answering the following questions: ? What process units should be used and how should they be interconnected (process synthesis)? ? What are the optimal feedstocks? What are their flowrates? When should they be used (process scheduling and operation) ? What is the process performance (process simulation)? ? Are there opportunities of conserving mass and energy (process integration)? ? What is the sensitivity of the identified solution to economic changes (process sensitivity)?

A multi-period optimization formulation is developed to provide a framework for process synthesis and scheduling. The formulation addresses the issues of supply and inventory availability and cost, feedstock mixing and segregation, and processing pathways. Mass, energy, and property integration techniques are used to conserve process resources. An economic-environmental-technical analysis is developed to assess the process performance under various cost and availability scenarios.