TBP APPARATUS
TBP Curve: is the most useful. However, no standard test exists for measuring the TBP. Most common TBP test is Hempel& D-285. TBP/ASTM distillation curves:are the most important characterization properties of the crude/intermediate/product streams. Both TBP, ASTM distillation curves are measured at 1 atm pressure. In both these cases, the boiling points of various volume fractions are being measured. The basic difference between TBP curve and ASTM distillation curve is that while TBP curve is measured using batch distillation apparatus consisting of no
less than 100 trays and very high reflux ratio, the ASTM distillation is measured in a single stage apparatus without any reflux. When a refining company evaluates its own crude oils to determine the most desirable processing sequence to obtain the required products, its own laboratories will provide data concerning the distillation and processing of the oil and its fractions. In many cases, information not readily available is desired concerning the processing qualities of crude oils. In such instances, true boiling point (TBP) and gravity-midpercent curves can be developed from U.S. Bureau of Mines crude petroleum analysis data sheets A:True boiling point distillation (TBP) for crude used to obtain true boiling point distillation curve good fractionation. Number of plates and amount of reflux must specified. Theoretically, a true boiling point (TBP) distillation is that where a very close separation is made so that each component in the mixture is separated at its own boiling point and the quantity present in the original mixture. – True Boiling Point(TBP)(ASTM D2892) • 10 to 20 theroretical stages near infinite reflux. • 1 atm; no hotter than 650oF minimize cracking. Large no. of stages and a high reflux to distillate ratio so as the temperature at any point on temperature Vs volumetric yields curve represents the actual boiling (true boiling) points of the hydrocarbon material present at the Vol. % point.