Emission reduction of regenerative fuel powered co-generation plants with SCR- and oxiidation-catalysts

摘要

Since the beginning of combustion engine development in this recent century various different fuels have been successfully tested. Diesel engines have been adapted to fuels made from mineral oils because of the rising importance and the cheapness in comparison to other fuels. On the other hand, it is possible to burn regenerative fuels in engines and achieve some significant advantages in comparison to fossil diesel fuel. This is, for example, a closed carbon dioxide (CO_2) cycle which causes no green house effect. It is possible to extract oil from various seeds like rapeseed. It is also possible to burn used oil from the food processing industry or waste grease and oil from food recycling companies. The great advantages: (1) food recycling oils can produce energy instead of use as animal food, and (2) as nobody knows exactly the consistency of the collected oils, poisonous pollution is possible. These regenerative fuels can be burned without any further processing in special adapted diesel engines, for example an Elsbett engine, or in precombustion engines with large swept volumes. Most researchers focused on operating diesel engines with regenerative fuels and reducing the emissions caring only about regulated exhaust components. In comparison to these studies it is necessary to learn more about the emissions beyond the exhaust regulations. Additionally emission reduction is possible by using an SCR-catalyst (selective catalytic reduction) to reduce the NO_2 combined with an oxidation-catalyst which reduces any kind of oxidisable emissions. The TU Munchen, Lehrstuhl fur Energie- und Umwelttechnik der Lebensmittelindustrie, operates a small co-generation plant with the ability of analysing the standard emission components (CO, NO_2, HC, particles, CO_2, O_2) and unregulated components (SO_2, NH_3, polycyclic aromatic hydrocarbons (PAH), aldehyde, ketone). The emissions how some significant differences in comparison to fossil diesel fuel which is caused by the diversity of each fuel. Results of an investigation on four different fuels (wastefat methyl ester (WME), rapeseed methyl ester (RME), rapeseed oil and diesel fuel) burned in a small co-generation plant with a SCR- and oxidation-catalyst will be presented. A comparison to the emissions before and after the catalysts will be shown additionally to the results of the different reduction potential of diesel fuel, methyl ester or untreated oils. The combination of regenerative fuel and catalyst shows good potential for reducing the emissions. Furthermore the use of regenerative fuels is a sustainable production of energy with an overall efficiency of almost 90%. Regenerative fuels based on vegetable oils and waste fat are a valuable form of energy and have some significant advantages in comparison to diesel fuel, like an almost closed carbon dioxide cycle, rapid biological decomposition and lower CO, HC and particle emissions. Regenerative fuels should also meet minimum standards discussed in the paper to avoid the risk of engine damage and to reduce emissions.