1. Flash distillation is a simple separation process where a liquid stream is partially vaporized in a flash drum, resulting in vapor and liquid phases enriched in the more and less volatile components respectively. 2. For a binary mixture, the vapor and liquid compositions (y and x) can be determined from phase equilibrium relationships using variables like temperature, pressure, or vapor/liquid fraction. Bubble and dew points, where boiling or condensation begin, are found by solving material and equilibrium equations. 3. The flash drum design involves specifying two variables like temperature, pressure, or heat input and solving the material and energy balances along with equilibrium relationships to determine the remaining variables of vapor and liquid flow rates, compositions and heat