Method for purifying a chlorine supply

A distillation system for purifying a chlorine supply comprising a chlorine component, a bromine component, and nitrogen trichloride, said distillation system forming purified chlorine gas having less than 20 parts by weight of said bromine component per one million parts by weight of said purified chlorine gas and forming a distillate comprising liquid chlorine and said bromine component, said system fluidly connected to a vaporizer and comprising:

• A. a distillation tower that has an upper end, a lower end, a vertical axis extending through said upper and lower ends, wherein said upper end has a diameter that is greater than a diameter of said lower end, and wherein said distillation tower comprises a plurality of horizontal trays to provide a vapor-liquid interface between a vapor and a condensate,
• B. a reflux condenser disposed above said distillation tower, in fluid communication with said upper end of said distillation tower, and sharing the vertical axis with said distillation tower and
• C. a reboiler disposed below said distillation tower and in fluid communication with said lower end of the distillation tower, wherein said reflux condenser, said reboiler, and a vapor input to said distillation tower are electronically coupled to a flow controlling device for controlling a rate of introducing a vapor into the distillation system through the vapor input as a function of an amount of condensate that flows from said reflux condenser into said upper end of said distillation tower and as a function of an amount of vapor formed from said reboilers,
• wherein said vaporizer heats the chlorine supply to a temperature of from 50° C. to 120° C.