Technical Committee Fuel Oils

Formation of Micro Emulsions (water/oil); their stabilizing Mechanisms and their Influence on operating Safety of Middle Distillates, for example of Light Heating Oil, Heating Oil A and Bio in technical Applications

The projects aim was to investigate the mechanisms of formation and transportation of water-in-oil emulsions and their stability and effect on heating oil burner systems. Additionally, the influence on the chemical-physical properties of the fuel in dependency of a microbial contamination with a defined mix-culture was determined. Furthermore, the effect of emulsions on the formation of a free water phase and the survival and the transport of microorganisms in the fuel should be characterized. Due to the preparation of a defined and representative mix culture, reproducible test series were possible. A direct influence of various heating oil qualities on the growth behavior was observed. Here, compared to heating oil – FAME blends, stronger growth in pure heating oil was watched sporadically. The surface tension of the water phase was lowered due to the diffusion of the FAME in the water phase, which was shown via gas chromatography. Some heating oil qualities also reduce the surface tension. In some cases, refueling (with contaminated water / fuel or both phases) led to faster grow-rates. In the test series of the screening test, no suction of the biofilm via the pump was observed, which was formed during growth. There was also no formation of a free water phase in the filter cup. The development of a static corrosion test showed the influence of a microbial contamination as well as of biofilms on the corrosive behavior of the fuel. It is assumed, that the transport of organisms and metabolic products through the system is enabled by the formation of micro-emulsions. Here, the survival of the organisms is ensured too. In this project, not just a microbial contamination, but also some fuel qualities led to a formation of a micro-emulsion. Due to the results of the project, it is assumed, that the probability of an entrance of organisms, their metabolic products and of water in the whole tank system through the suction of a free water phase via the pump is significantly higher than due to micro-emulsions.

The IGF project (18163 N) of the research association DGMK Deutsche Wissenschaftliche Gesellschaft für Erdöl, Erdgas und Kohle e.V., Überseering 40, 22297 Hamburg was funded by the Federal Ministry for Economic Affairs and Energy via the AiF within the framework of the programme for the promotion of joint industrial research (IGF) on the basis of a resolution of the German Bundestag.