Isothermal Flash Tank (VLE)
Calculate vapor/liquid split and phase compositions using the Rachford-Rice equation and Wilson K-values.
Flash Conditions
Feed Composition
Search and add components. Values will be automatically normalized to 100%.
About This Tool
The Isothermal Flash Tank Calculator (Vapor-Liquid Equilibrium) is a core process engineering tool used to predict phase separation. When a pressurized liquid mixture (like a hydrocarbon stream) experiences a pressure drop, a portion of it will "flash" into vapor.
This tool replaces heavy simulation software (like Aspen HYSYS) for quick, on-the-fly calculations of knock-out drums, separators, and flare header loads.
Thermodynamic Methodology (Rachford-Rice)
1. Wilson K-Values
The tool first calculates the equilibrium constant ($K_i = y_i / x_i$) for every component using the Wilson equation. This relies on the Critical Temperature ($T_c$), Critical Pressure ($P_c$), and Acentric Factor ($\omega$) of the specific hydrocarbons.
2. The Rachford-Rice Equation
Once K-values are established, the engine utilizes a Bisection root-finding algorithm to solve the highly non-linear Rachford-Rice objective function for the vapor mole fraction ($V$):∑ [ z_i * (K_i - 1) / (1 + V * (K_i - 1)) ] = 0
Related Fundamentals
Input / Output Units
Specific to the active calculator.