A new hydrate based process for drying liquids

We present a novel process for drying chlorine by formation of a clathrate hydrate. Liquid chlorine is dried in a rotor-stator spinning disc (RSSD) heat exchanger, which has heat transfer coefficients up to 10 kW/m2/K, independent of the flow rate. Benefits of this novel drying process are (1) compactness of the spinning disc heat exchanger, minimizing material investments, (2) blocking of the equipment by the adhesive hydrates is prevented by the rotation, and (3) no chlorine contamination by drying agents, e.g., sulfuric acid or zeolite. Batch and RSSD experiments were performed with dichloromethane as a model compound for liquid chlorine. Lower crystallization temperatures result in shorter induction times of the hydrate formation and thus faster water removal rates. Higher mass transfer rates at higher rotation speeds have the same effect. The results show that the RSSD heat exchanger facilitates an elegant, energy-efficient water removal process that can be applied to removal of trace amounts of water from hydrate forming liquids.