The Braun-K10 method (BK10) is based on the charts developed by Cajander, et. al., in 1960. The chart for a convergence pressure of 5000 psia is used to predict the component K-values at a system pressure of 10 psia. The K-values at 10 psia are ratioed to the desired pressure.
This method has limited capability to predict the K-values for light components and uses gross approximations for H2, N2, O2, CO, CO2 and H2S. For aromatic compounds, a vapor pressure correlation is used for K10 values of 2.5 or less. Pseudocomponents are estimated using a correlation of K10 values and boiling points.
For additional information, see "Braun K10 (BK10)" under "Generalized Correlation Methods" in Chapter 2, Volume 1, of the PRO/II Reference Manual.
Application Guidelines
This method usually gives reasonable results for refinery heavy ends columns operating at low pressures. If the light ends distribution in the column is important another method should be used. The method should never be used for systems at pressures higher than 70 psia or temperatures outside the range 100 - 900 degrees F. Because the composition effect on K-values is ignored, it can be expected to yield poor results for mixtures of aromatics with paraffins, naphthenes and olefins.