This SBIR Phase I project will develop a water separator media to protect heavy duty engines from the water content in modern ultra low sulfur diesel fuels. The ultra low sulfur diesel fuel typically found in the field has very low interfacial tension allowing water to be present in the form of very fine droplets which pass through conventional water separators and end up in the fuel injection system. This project will quantify and develop a functionalized multiwall carbon nanotube-based water separator to be used with all ultra low sulfur diesel fuels on the market with nearly 100% water removal efficiency. The objective is to enhance the separator performance to cost ratio by working to further increase the separation efficiency and lower the media cost through process scaling and materials development.
The broader impact/commercial potential of the project are focused on benefits related to enhanced ultra low sulfur diesel fuel separation, including more consistent fuel delivery to the engine, longer injector/engine life, better combustion of ultra low sulfur diesel fuel, lower maintenance costs, new jobs enabled by the use of high-sulfur fuel reserves, and more efficient combustion of bio-fuels. Reduced water content in the fuel will help to improve performance of the high pressure fuel injection systems, maintain tolerances of the fuel injection system components, and reduce maintenance costs.
This Phase II project addressed emerging problems in liquid-liquid separation by taking advantage of carbon nanotube science and technology. There are several devices currently on the market that are designed to separate water from fuels for improved engine efficiency. The challenge, however, is to separate water from the newest fuels on the market; low interfacial tension (IFT) fuels such as ultra-low sulfur diesel (ULSD) and biodiesel and its blends (B20, B40, B60, etc.). B-10 and B-20 fuels are currently being used in many places and an EPA mandate requires a 100% conversion of diesel to ULSD by 2014. The higher water-fuel emulsion stabilities and hygroscopic nature of these fuels make water separation a difficult problem with no adequate commercial solution. Current composite media based separators fail to provide the necessary product performance over the board range of commercial ULSD fuels. An alternative separation technology, distillation columns, is costly and too complex to be installed at every gas station, and is not feasible for mobile applications. A major impediment to making an effective ULSD-water separation composite media is the lack of a small-diameter, high-surface-area, highly-stable-in-fuel, chemically modifiable, and strong fibrous material. Multi-walled carbon nanotubes hold great promise for this application as they address all those shortcomings. The technical difficulty with ULSD is that various commercial sources have differing physical properties and hence exhibit varying emulsion stabilities. Because the process of stripping sulfur (hydrodesulphurization) from diesel reduces the natural lubricity of the resultant ULSD, lubricity additives are used to restore the fuel lubricity to the required value. As different ULSD suppliers have different lubricities initially, they end up adding a variety of types and amounts of lubricity restoring additives to the diesel fuel. Lubricity additives’ molecules have both hydrophilic and hydrophobic components, and hence also act as surfactants. The higher the content of lubricity additive in ULSD, the higher the emulsion stabilities, and the more difficult it is to separate water from the fuel. The need for a universal ULSD-water separation device for mobile applications is imperative. That will enable customers to use ULSD fuel from the broad range of available ULSD fuel formulations and still have the necessary water separation efficiency for engine reliability. Through this research Seldon not only fabricated a carbon nanotube based media which solved this problem but also made it feasible for commercialization. During this period Seldon worked with a potential partner to evaluate this media which demonstrated > 99% removal of emulsified water and >97.5% removal of 4 µm(c) medium test dust particles. The media exceeded the life of a competitive composite media by 13%. This performance makes Seldon’s media ideal for filtration and separation applications in common rail engine systems where the injectors need protection from the wear and tear caused by to emulsified water and small particles. Additional benefits are derived from the fact that carbon nanotubes prohibit any static charge build up within the media. This allows the customer to reduce the weight of the final product by removing the heavy and costly metal components from the system. Seldon is actively seeking potential commercialization partners to realize the great benefits of this new filtration and separation technology. Seldon projects that the commercialization of this technology with a potential fuel system partner could see annual sales exceed $10 M within the next 5 years. Additional commercial partners and application of this new technology in related fields are expected to add significant sales in future years.
