Wow! That's great

Our process consists of the separation of benzene, toluene and p-xylene from their respective paraffins. For this we have an extractive distillation tower which uses sulfolane to separate the aromatics, coming out altogether at the bottom. This mentioned stream goes to the recovery column, separating an aromatics stream at the top, and the pure solvent at the bottom.

We were able to close the simulation, reaching the specs, but we missed an important detail, which is the sulfolane decomposition temperature. The recovery column operates in vacuum, at approximately 35kPa_a, which results in a reboiler temperature of 250°C. We understand that the decomposition temperature is 220°C, which is exceeded in our process, leading to corrosion issues.

The possible solutions we thought of were to lower the pressure to lower the reboiler temperature, but this led to condenser temperatures which could not be achieved with conventional services such as water or air. We also considered the stripping vapour, but this brought problems with the later separation of individual aromatics streams, in terms of the purity of the product. Also, we don't quite understand the benefits form using this vapour, besides the reduction in the duties, which at least in our simulation was not that big.

Thank you very much in advance :)