to the first heat exchanger as cooling medium fig2 also shows a side draw off stream i from the distillation column to remove intermediate boiling contaminants this stream can be fed to an activated charcoal bed 8 to remove organics resulting in stream i u2032 which is led off to disposal fig2 also shows purified gas stream g being fed to an activated charcoal bed 7 resulting in a stream g u2032 of purified hydrogen chloride gas the embodiment shown in fig3 is identical to that shown in fig2 except that the bottom liquids of the distillation column are fed via stream h to a reboiler 11 that is provided with an appropriate coolant via stream shown in the figure as arrows entering one side of the exchanger and exiting on the other side to generate stripping vapors that are fed via stream k to the bottom portion of the column the reboiler heats the bottoms liquid at low heat flux to prevent foaming action the condensate stream h u2032 u2033 from the reboiler can either be collected and discarded or can be sent to either the third heat exchanger stream h u2032 or back to the inlet of the first heat exchanger.