- Title
- Hydrothermal liquefaction of scenedesmus obliquus in a continuous reactor system
- Creator
- Kaufmann, Gideon
- Subject
- Biomass chemicals Microalgae -- Biotechnology
- Subject
- Supercritical fluids
- Date Issued
- 2013
- Date
- 2013
- Type
- Thesis
- Type
- Masters
- Type
- MTech
- Identifier
- http://hdl.handle.net/10948/47878
- Identifier
- vital:40393
- Description
- In 2009 InnoVenton, a research institute at the Nelson Mandela Metropolitan University (NMMU) set out to establish a technological concept of micro-algae to fuel, at which point an algae farm was established. The overall research strategy is envisaged to focus on a number of potential uses of algae biomass and related processes such as water treatment can take place, the binding of the biomass to coal fines to create briquettes are possible, and bio crude production from direct liquefaction. This project will focus on the latter. In 2010 a partnership between NMMU and the University of Cape Town’s (UCT) Department of Chemical Engineering was established to design, construct and commission a test unit that could convert the algae biomass into a pumpable bio crude by the liquefaction process. During the initial operation of this test unit, flow problems of the reaction product were observed. As such, the aim of this study is to investigate a number of process conditions and develop strategies to minimise or alleviate this problem. As part of this study, UCT will replicate the NMMU test unit in Cape Town in order to start focussing on finding relevant solutions to the problems which exist. Presently continuous reactor systems are not used for the liquefaction of micro-algae. According to Toor, et al(2011)¹ Other feedstocks have been placed in continuous reactor systems with good end results. They continue to write in their review that batch systems were used in most experiments. If micro-algae are to become a competitive alternative to crude oil then batch systems are not the way forward. From a commercial and efficiency standpoint, there are significant advantages to move from typical batch reactors to continuous reactors, specifically in terms of downtime and loading/unloading of vessels. From the evidence gathered in Port Elizabeth, the nature of the reaction product caused typical plugflow reactor systems to block. The aim of this study is to investigate possible solutions to the problem of the reactor system blockage and thus pave the way for the implementation of a continuous reactor system. There are many variables which can be manipulated to achieve success for example the use of catalysts, co-feeding of reactant gases like hydrogen, residence time, temperature or pressure. Manipulating these variable can help to change conversion and/or product spectrum. The results of this study will be compared to results obtained by typical batch experimentation conducted at NMMU. This research varied temperature only. This variation was effective enough to find solutions to the obstacles that were present. Once the algae feedstock was being diverted to the vent pot via the safety relief valve, it was understood that something was blocked. Once the reactor was cooled and removed, it was apparent that the reactor was not blocking up however the exit line to the product catch pot was. To solve this problem a new heated zone was created. This heated the exit line and the top of the product catch pot to around 50°C below the reaction temperature. This upgrade to the system made the oil liquor less vicous and flow easier. The exit line never blocked up again during the research. Energy values of the product were comparable to that of coal. Higher reaction temperatures favoured the production of paraffins and olefins while lower reaction temperatures favoured the production of oxygenates. An ampoule sampler was introduced to take samples of the gas exit line. The comprehensive gas chromatography analysis of the gas in the ampoules revealed that eventhough the concentration of the products present were low, there were significant quantities of paraffins present in the gas stream. More research and the variation of variables discussed previously need to be conducted. It is also apparent that the test unit needs to be upgraded to a bigger reactor and possibly to use materials of construction which do not corrode easily. A computer model could be developed in conjunction with the current test unit and then a bigger reactor might not be needed. The reducing of the oxygen content in the final bio crude also needs to be investigated. Overall the research is very promising in the fact that the final bio crude that was produced is comparable to coal. With further research it will be possible to create a product that is comparable to fossil crude oil and then could be used as a supplement to crude oil.
- Format
- viii, 75 leaves
- Format
- Publisher
- Nelson Mandela Metropolitan University
- Publisher
- Faculty of Science
- Language
- English
- Rights
- Nelson Mandela Metropolitan University
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NMMU School of BioMolecular and Chemical Sciences
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | Gideon Kaufmann.pdf | 4 MB | Adobe Acrobat PDF | View Details Download |