The GS method is based on the Chao-Seader method. It represents an attempt by Grayson and Streed to extend the Chao-Seader approach to the higher temperatures and pressures encountered in oil refining. Grayson and Streed also fit special equations for the liquid fugacities of methane and hydrogen, using data available from hydrocracking operations.
More information on this method, see "Grayson-Streed" under "Generalized Correlation Methods" in Chapter 2, Volume 1, of the PRO/II Reference Manual.
Application Guidelines
Refinery heavy ends columns such as crude, vacuum, FCC main fractionators and coker columns. It may also be used for most refinery gas plant operations and hydrogen processes such as reforming and hydrocracking. For hydrocracking, more accurate hydrogen solubilities are predicted by using one of the SRK modifications. General limits are pressures less than 3000 psia and temperatures less than 800 degrees F, although the method usually extrapolates reasonably well with temperature.