Characteristics of Cetane index of traditional diesel oil in Wonocolo district, Bojonegoro

Abstract

There are many old oil wells in Indonesia which are no longer operated by the state-owned oil company Pertamina. Those wells have no longer a sufficient amount of oil to be extracted continuously. One such oil field is located in Wonocolo district, Bojonegoro in East Java Province. Local miners are allowed to operate oil mining by using very simple equipment. Currently, there are around 235 wells. Each well produces 300 to 350 barrels of crude oil per day and was operated two times a week. The crude was sold to Pertamina, but some of the crudes were processed by the miners by using a traditional distillation system called pawon. At least there are 190 pawon in the Wonocolo district. The crude is processed into diesel oil. The oil is sold to the market with a price of IDR 2,750. It is almost half of the price of the regular diesel oil sold by Pertamina, IDR 5,500 per liter. The objective of this study is to increase the quality of traditional diesel oil by applying simple blending operations. To achieve this objective, diesel oils produced by different pawon are treated as feedstock with different grades. This study aims to determine the characteristics of traditional diesel oil based on the Cetane Index value. The characterization was done by grouping the diesel oil based on its density. Traditional diesel oil is divided into 3 (three) grades based on its density. To obtain the Cetane Index value, the density and the distillation profile of diesel oil is needed. The ASTM D1298 ASTM D86 methods were used to obtain the density and distillation profile of the diesel oil. Cetane Index calculation was carried out by using ASTM D976 and ASTM D4737. The calculation results of the Cetane Index ASTM D976 are 50.66, 47.59, and 45.24 for Grade 1, Grade 2, and Grade 3, respectively. The calculation results of the Cetane Index ASTM D4737 are 47.04, 45.08, and 43.47 for Grade 1, Grade 2, and Grade 3, respectively. This information can be used to optimize the quality of the traditional diesel oil by diesel blending optimization.