Pokoo-Aikins, Grace Amarachukwu (2010-08). Design and Analysis of Flexible Biodiesel Processes with Multiple Feedstocks. Doctoral Dissertation. Thesis uri icon

abstract

  • With the growing interest in converting a wide variety of biomass-based

    feedstocks to biofuels, there is a need to develop effective procedures for the design and

    optimization of multi-feedstock biorefineries. The unifying goal of this work is the

    development of systematic methodologies and procedures for designing flexible multifeedstock

    biorefineries. This work addresses four problems that constitute building

    blocks towards achieving the unifying goal of the dissertation.

    The first problem addresses the design and techno-economic analysis of an

    integrated system for the production of biodiesel from algal oil. With the sequestration

    of carbon dioxide from power plant flue gases, algae growth and processing has the

    potential to reduce greenhouse gas emissions. Algae are a non-food oil feedstock source

    and various pathways and technologies for obtaining algal oil were investigated.

    Detailed economic and sensitivity analysis reveal specific scenarios that lead to

    profitability of algal oil as an alternative feedstock. In the second problem, a new safety metric is introduced and utilized in process

    design and selection. A case study was solved to assess the potential of producing

    biodiesel from sewage sludge. The entire process was evaluated based on multiple

    criteria including cost, technology and safety.

    The third problem is concerned with incorporating flexibility in the design phase

    of the development of multi-feedstock biofuel production processes. A mathematical

    formulation is developed for determining the optimal flexible design for a biorefinery

    that is to accommodate the use of multiple feedstocks. Various objective functions may

    be utilized for the flexible plant depending on the purpose of the flexibility analysis and

    a case study is presented to demonstrate one such objective function.

    Finally, the development of a systematic procedure for incorporating flexibility

    and heat integration in the design phase of a flexible feedstock production process is

    introduced for the fourth problem. A mathematical formulation is developed for use in

    determining the heat exchange network design. By incorporating the feedstock scenarios

    under investigation, a mixed integer linear program is generated and a flexible heat

    exchange network scheme can be developed. The solution provides for a network that

    can accommodate the heating and cooling demands of the various scenarios while

    meeting minimum utility targets.

publication date

  • August 2010