The research described in this dissertation was motivated by the global demand for energy that is not dependent on coal, oil, natural gas and other non-renewable fossil fuels. The technology used in this project is related to the use of biomass to produce a viable alternative to conventional sources of fuel. A bench scale biomass to liquid (BTL) facility was built and tested. This produced results confirming the feasibility of the BTL process. The findings of the pilot study outlined in this dissertation justified the conclusion that the next step will be to expand the capacity and productivity of the BTL pilot plant to an industrial scale. Biomass comes from a variety of renewable sources that are readily available. In this case, the material used in the fixed bed biomass gasification facility to generate wood gas was agricultural and forestry waste, such as straw and wood chips. The gasifier had the capacity to produce up to 10 cubic metres/hr of gas with a carbon monoxide and hydrogen content of between 20–40% by volume, when it was operated at ambient pressure and with air as the oxidizer. The gas, produced at a temperature above 700º C, was cooled in a quench/water scrubber in order to remove most of the mechanical impurities (tars and water-soluble inorganic particles), condensed and dried with corn cobs before being compressed in cylinders at over 100 bar (g) for use in the Fischer-Tropsch Synthesis (FTS). The syngas was subjected further to a series of refining processes which included removal of sulphur and oxygen. The sulphur removal technology chosen entailed applying modified activated carbon to adsorb H2S with the help of hydrolysis in order to convert organic sulphur impurities into H2S which reduced the sulphur content of the gas to less than 5 ppbv. Supported cobalt catalyst (100 grams), were loaded into a single-tube fixed bed FT reactor with an inner diameter of 50 mm. The reactor was fitted with a heating jacket through which, heated oil ran to cool the reactor during a normal reaction occurring at < 250 ºC, while nitrogen was used in the heating jacket during reduction, which occurred at temperatures up ~ 350 ºC. The FTS reaction was carried out at different pressures and temperatures. Liquid and wax products were produced from the facility. The properties of the liquid and solid hydrocarbons produced were found to be the same as FT products from other feed stocks, such as natural gas and coal.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufh/vital:26499 |
| Date | January 2014 |
| Creators | Zhang, Yusheng |
| Publisher | University of Fort Hare, Faculty of Science & Agriculture |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis, Masters, MSc (Chemistry) |
| Format | pdf, 140 leaves; 30 cm |
| Rights | University of Fort Hare |
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