Boiling Point Distribution Of Crude Oils Based On Tbp And Astm D-86 Distillation Data

Petroleum & Coal 53 (4) 275-290, 2011
Boiling Point Distribution Of Crude Oils Based On Tbp And Astm D-86 Distillation Data
Angel Nedelchev, Dicho Stratiev, Atanas Ivanov, Georgy Stoilov
Lukoil Neftochim Bourgas – Chief Process Engineer Department, 8104 Bourgas, Bulgaria, Nedelchev.Angel.D@neftochim.bg, Stratiev.Dicho@neftochim.bg
Abstract
The True Boiling Point (TBP) analysis according to ASTM D-2892 standard is the most reliable tool for characterization of crude oil and petroleum mixtures in terms of their boiling point distribution. However, the procedure is expensive and time consuming, which is inappropriate for quick estimation of crude oil distillation characteristics. Thirty three crude oil samples were characterized by means of TBP distillation and ASTM D-86.
This paper presents an attempt to test the applicability of the major methods available in the open literature for converting ASTM D-86 to TBP for the whole range of the distillation curve. The whole distillation curve was obtained by using the Riazi’s distribution model ((Ti-To)/To=[АT/ВT.Ln( 1/(1-xi))]1/BT), which demonstrated high accuracy with r2 ≥ 0.99. All methods demonstrated lower accuracy in converting the ASTM D-86 into TBP than the reproducibility of the ASTM D-2892.
Introduction [Excerpt]
Having in mind that crude oil cost accounts for more than 80% of refinery expenditure the proper operation of crude distillation unit has great impact on refinery profitability. In order to find the adequate technological regime that provides maximum yields of high value products in a crude distillation unit the process engineer needs to have laboratory analyses data of crude oil that is processed in the unit. The True boiling point distillation (TBP) is the single most important information for any crude oil for modeling of a crude distillation column. The TBP distillation tends to separate the individual mixture components relatively sharply in order of boiling point and is a good approximation of the separation that may be expected in the plant. Unfortunately the TBP analyses are costly and time consuming, a TBP analysis takes about 48 hours. That is why it is impractical to use it as a tool for daily monitoring of the crude distillation unit operation. For refineries, which often switch the crude oils the lack of information about the crude oil quality could negatively impact the optimum operation and in this way the profitability of the crude distillation unit. It was found that boiling point distribution of crude oils and oil fractions obey the Riazi’s distribution model
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