Extraction of rape seed oil and farm operation of an Elsbett engine tractor
This Licentiate thesis deals with small-scale extraction of rape seed oil and the use of this oil in an Elsbett engine tractor. Small-scale extraction of rape seed oil was studied in practical tests in the laboratory at Ultuna, Uppsala. The influence of the speed of the press screw, nozzle size and nozzle performance, the distance between the press screw and the press chamber head, the ambient temperature, and preheating of the seed with air was studied. At Sjösa farm a small plant for on-farm extraction of rape seed oil was built. The processing of three bigger batches of oil seed was studied. Data of interest were registered in an operating log. Capacity and oil extraction efficiency were studied. A tractor with an Elsbett engine was operated at Sjösa farm on the processed rape seed oil. Data of interest were registered in an operating log and with an automatic data collection system. The data obtained on the farm were used to conduct an energy analysis. The oil press has higher capacity with bigger nozzles and higher screw speeds. However, the amount of oil extracted from each seed increased if the nozzles were smaller and/or the press screw speed was lower. Nozzles with a long press nozzle channel gave a more solid meal. It was important that the temperature in the press chamber head reached a temperature of about 70°C. The optimum seed moisture content (wet basis) was 7-8 per cent. Preheating with air usually improved the capacity, but there is a risk of over-drying so it must be done with care. Preheated seed involves a risk of getting too high levels of phosphorus in the oil. On the farm, the simplest way of cleaning the oil is settling. This can be done in three series-coupled sedimentation tanks. If the ambient temperature is +20°C and the settling height is 0.6 m, about 18 days are needed for the settling. A tractor with an Elsbett engine can be operated almost in the same way as a conventional tractor. The differences are rape seed oil fuel, separate starting fuel, more frequent fuel filter exchange, electrical heating of the fuel system and about 10 per cent higher fuel consumption. Problems may occur when the rape seed oil stiffens at -15°C. To obtain a good energy balance it is important to have a high yield and low moisture contents. It is important also to have uses for the meal and straw. Direct seeding also improves the energy balance. The main conclusion of the project is that a system involving rape seed oil and the Elsbett engine works well technically. The system is not, however, competitive as there are cheap fossil fuels on the market, and the Elsbett engine has not yet entered serial production. In addition, the supply of rape seed oil in Sweden is limited, and the oil produced could be used for better purposes than as vehicle fuel.
vegetable oil; rape seed oil; rape oil; oil extraction; oil expression; oil pressing; Elsbett engine; fuel; bio fuel; energy; bio energy; renewable energy; energy balances; energy analysis
Rapport - Sveriges lantbruksuniversitet, Institutionen för lantbruksteknik
Publisher: Institutionen för lantbruksteknik, Sveriges lantbruksuniversitet
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