Novel intensified liquid-liquid contactors for mass transfer in sustainable energy generation.

点击翻译按钮获取中文摘要

The rapid growth of the population worldwide and the drive for economic development rely on continuous supply of energy, with global needs estimated to increase by 50% by 2035. Although fossil fuels are still the primary energy source, the problems associated with security of supply and the environmental impact because of the CO2 emissions, are going to limit their use in the foreseeable future. Low carbon and renewable energy sources, such as nuclear and biofuels, which are increasingly used, will meet progressively these energy demands. Nuclear energy from fission is a low carbon source and can provide large amounts of electricity and process heat using only small amounts of raw material. However, one of the main concerns in the nuclear fuel cycle is the management of the radioactive waste which can remain toxic for thousands of years. The expansion in nuclear power generation makes the problem of nuclear waste management particularly acute. Reprocessing of nuclear fuel can potentially recover the remaining actinides and fission products, and reduce the volume and toxicity of the spent fuel for storage or disposal in geological repositories. However, reprocessing has been associated with high costs, making the direct storage and ultimate disposal of high level waste the preferred option. Liquid-liquid extraction technologies are essential in spent nuclear fuel reprocessing where currently used contactors are decades old and are not well characterised.In this project we will develop novel liquid-liquid contactors for extraction processes that will intensify the production of energy from alternative and sustainable sources. Intensification addresses the need for materials and energy savings and contributes significantly to the competitiveness of process industries worldwide by making industrial processes faster, more efficient and less damaging to the environment. Substantial process intensification is possible with the use of small scale contactors, where the reduced length scales result in thin fluid films which enhance mass transfer rates, while the increased surface to volume ratios enable the controlled formation of well characterised flow patterns. We will develop two concepts to intensify liquid-liquid extractions and increase throughputs to industrial levels. The first approach involves an intensified impinging-jets contactor, where the two liquid phases collide at high velocities in the small space of the contactors; the intense mixing and high energy dissipation rates at the zone of collision form dispersions with small drop sizes and narrow distributions that have large interfacial areas. The second approach involves scale up of the process by increasing the number of small channels used (scale out). This approach differs from conventional scale up where the unit size is increased, and depends on the design of the flow distributor that feeds the channels. The research will be carried out in collaboration with two industrial partners, i.e. NNL which develops nuclear fuel reprocessing technologies and Greenegy that produces biodiesel. The active involvement and support of the partners in the project will facilitate technology transfer.