A similar concept was proposed by Pan et al. and was applied to a laboratory scale Kaibel DWC for the separation of an equimolar mixture of methanol, ethanol, n-propanol, and nbutanol. The start-up process consists of three phases: total reflux, followed by a batch distillation phase and a continuous phase. Initially, the reboiler is filled with the feed mixture and the reboiler is switched on. After a circulation of vapor and liquid streams between the bottom and the top of the column has established, the light component at the top is withdrawn manually until the distillate purity reaches a value of 90 mol%. This process is repeated for the upper and lower side products. The feed mixture is then fed into the column in the continuous phase and all product streams are withdrawn simultaneously. Over the whole start-up process, the product purities are analyzed every 13 min with the help of a gas chromatograph. Stable operation of the column was reported after 3.5 h.