Masters Degrees (Chemical Engineering)

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Browsing Masters Degrees (Chemical Engineering) by Subject "Acrylonitrile -- South Africa"

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    Techno-economic analysis for the production of acrylonitrile, propylene or isosorbide in a sugarcane biorefinery annexed to a typical South African sugar mill
    (Stellenbosch : Stellenbosch University, 2024-03) Rode, Lukhanyo; Görgens, Johann Ferdinand; Petersen, Abdul M.; Stellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Process Engineering.
    ENGLISH ABSTRACT: The decrease in non-renewable resources and the demand for sugar in market has sparked an interest in seeking other greener pastures. Biorefineries have a capability of producing a wide range of products from renewable resources such as surplus sugar, which can replace products that are fossil fuel dependent and introduce a circular economy. The present study specifically considers propylene, acrylonitrile and isosorbide as potential, high-value products can be manufactured in sugar mill biorefineries, considering the technical, economic and environmental aspects of feasibility. The project’s aim was to investigate whether a sustainable and profitable 1G biorefinery can be built by using molasses as a feedstock to produce one of these products. The first objective of the project was to collect literature data for the different products that will be considered for a biorefinery simulation. The second objective was to build simulations in Aspen Plus® for the biorefineries using literature data and sound engineering assumptions, with each simulated scenario producing one potential product. Third objective was to determine the profitability of the biorefineries by calculating the minimum selling prices (MSPs) for an acceptable return on investment in a biorefinery producing one of the products using discounted cash flow rate of return analysis, to compare with market prices. The last objective was to assess the environmental impact associated with producing these different products in a biorefinery, this would be achieved by doing the greenhouse gas emission calculations. Sufficient technical data could be obtained from literature to develop biorefinery simulations for each of the three products of interest. The required MSPs from economic assessments of the simulated propylene biorefineries were $3933/t for propylene-from-ethanol and $8151/t for propylene-fromisopropanol. The propylene MSPs were 311%, 522% and 752%, 1190% above the prices of fossil-based propylene present in the market, respectively. Similarly, the MSPs for acrylonitrile were $4988/t for acrylonitrile-from-propylene (ethanol), $9468/t for acrylonitrile-from-propylene (isopropanol), and $5957/t acrylonitrile-from-3-hydroxypropionic acid. These were 326%, 375%, 399%; 709%, 802%, 847%; and 409%, 467%, 496% above the market prices of current fossil-based acrylonitrile. The propylene-from-ethanol and acrylonitrile-from-propylene (ethanol) sold cheaper than their relative routes this was due to the high overall product yield and low production costs they had in comparison to their alternative routes. The high yields owe it to the better fermentation yields of ethanol in comparison to isopropanol and 3-hydroxypropionic acid. The bio-based propylene and acrylonitrile therefore required very large “green” price premiums compared to their equivalent fossil fuel based products, owing to substantially higher production costs. Conversely the required MSP for isosorbide ($682/t) was 32% and 86% lower than the market prices, indicating a viable investment opportunity. The affordability of isosorbide was mainly due to the sales from mannitol and high yield. Isosorbide is a potential substitute for bisphenol A and its selling price is almost three times that of isosorbide further proving it is an attractive investment. Bio-propylene and acrylonitrile production is able reduce emission in comparison to their counter fossil fuel process. Propylene-from-ethanol and propylene-from-isopropanol had 84% to 94% and 63% to 97% in emission reductions against various fossil based propylene processes. Whereas acrylonitrilefrom-propylene (ethanol), acrylonitrile-from-propylene (isopropanol), and acrylonitrile-from-3- hydroxypropionic acid had 37%, 43%; 18%, 26%; and 8%, 16% in emission reductions, respectively. This was in comparison to the SOHIO (Standard Oil of Ohio) process. The isopropanol and 3- hydroxypropionic acid based biorefineries had lower emission reduction than their alternative routes this is influenced by the significant amount of ammonia used in the biorefineries. Finally, the isosorbide-from-sorbitol biorefinery had 118% more emissions than the improved isosorbide plant from Roquette. The Roquette plant implemented carbon capture to lower its emissions.