Date of Award

Fall 2019

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Civil/Environmental Engineering

Program/Concentration

Environmental Engineering

Committee Director

Sandeep Kumar

Committee Member

Mujde Erten-Unal

Committee Member

James W. Lee

Abstract

Increasing demand for renewable energy, fuels, and bioproducts has resulted in a push for increasingly efficient and economically favorable biomass pretreatment methods. Flash Hydrolysis, (FH) a promising biomass pretreatment method, has been extensively studied at a laboratory scale. FH employs a continuous subcritical hydrothermal process capable of fractionating microalgae for lipid and protein recovery. FH is unique in that the residence time is very short (~ 10 s). Maintaining this residence time was key in designing a scaled pilot flash hydrolyzing unit (FHU). We have developed a one of its kind pilot FHU capable of increasing the processing output of the laboratory scale 160 times, while maintaining the residence time and increasing heating rate in a continuous flow reactor.

This study tests a range of microalgae slurry concentration (1-10 wt%) in the pilot continuous FHU for fractionating algae components. The FH products mainly contain biofuels intermediate in solids (most of lipids) and hydrolyzate (soluble proteins and carbohydrates). Different concentration of microalgae can affect the heating rate and the products yield. It can also limit the pressure controlling ability of the backpressure regulators used in the process. Determining the algal slurry weight percentage in which the FHU can operate effective and efficiently is a vital step in the process of scaling FH. Two different microalgae species Scenedesmous and Chlorella were used in the range of 150-220ºC under subcritical water conditions. Besides the microalgae concentration effect, the study shares the experiences of designing, and operating one of its kind FHU for processing microalgae slurry.

DOI

10.25777/zh93-wv22

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