Distillation columns separate a liquid mixture into its component parts, based on the differences of volatilities. Vapor-liquid equilibrium holds at every stage of the column and is modeled by the so-called MESH equations, based on
thermodynamic models of the mixture. Computing the column equilibrium thus boils down to solving a system of nonlinear equations.

In this talk, we briefly introduce MESH equations that govern a distillation column, then we focus on global methods for solving nonlinear systems of equations. We present preliminary results using interval methods, a class of
global methods that handles roundoff errors.