Density and Standard Conditions

V4 strengthens Petro-SIM's understanding of standard conditions, allowing you to define your own settings. Previous versions always assumed 1 standard atmosphere pressure, with temperature being 15 °C for those working in metric display units (°C, K) and 60 F for those working in imperial display units (°F, R). V4 allows you to specify your own conditions, which are then independent of the display units of measure. You can set:

  • Standard Temperature (default = 60 °F)
  • Standard Pressure (default = 1 atm)
  • Reference Density of Water (default = 997.9879 kg/m3)
  • Reference T for Water density (default = 60 °F)

The primary use of these conditions is in density data entry and reporting. The Specific Gravity (Dry), API Gravity (Dry) and Liquid Mass Density (Std Cond) properties will respect these conditions, converting values between standard conditions and Petro-SIM's internal standard of Density at 60 °F. For example, if your standard conditions are the default, any Specific Gravity you enter for synthesis is converted from an SG at 60 F to a Density at 60 °F for use inside synthesis, with synthesis diagnostics reporting in terms of these density values. If you enter the Specific Gravity of a cut as 0.8000, this means that Synthesis will end up using a value of 0.7984. Change your standard conditions to correspond say to SG 15/4 (T=15°C, ρwater=1000.0 kg/m3 at 4°C) and your Specific Gravity of 0.8000 will be converted to a density at 15 °C and thence to a density at 60°F using a density correction method.

Many of the internal refinery property and reactor calculations in Petro-SIM work on the assumption that specific gravity and density are interchangeable, effectively assuming the density of water is 1 g/cc or 1000 kg/m3. These calculations and assumptions continue unchanged but the sharp-eyed may notice some apparent reporting discrepancies in diagnostics.

Density values for assay synthesis can be provided using four different properties:

  • Specific Gravity (Dry) – stores internally in SG units
  • API Gravity (Dry) – stores internally as unitless
  • Liquid Mass Density (Std Cond) (Dry) – stores internally in kg/m3
  • Density at user-specified T – stores internally in kg/m3

You can override the case standard conditions within an assay, allowing for you to import assays created on one basis into a case using a different basis.