HCl Gas Generation Unit (Calcium Chloride Route)


This plant has been designed by Super as a continuous process to produce dry HCl gas by the Azeotropic Distillation of 30% hydrochloric acid solution along with a co-current stream of calcium chloride solution.

A pre-heated steam of 30% hydrochloric acid solution and simultaneously a co-current stream of hot concentrated calcium chloride is fed to the azeotropic distillation column. The calcium chloride breaks the azeotrope formed between HCl and water and as a result almost all the HCl present in the solution is released in the form of gas.

The heat energy for the distillation process and the evaporation process is supplied by steam via heat exchangers acting as Thermosyphon reboilers. The vapour from the re-boiler strips the available gas from the feed acid solution in the column.

The condensation system at top of Azeotropic Distillation column consists of:

  • CW condenser cooled by cooling water
  • Chilled Brine Condenser cooled by chilled Brine

The top product HCl gas is dried in the Sulphuric acid trap. 98% Sulphuric acid to be charged in the glass vessel which absorbs moisture form HCl Gas. The moisture content in the product HCl gas is expected to be less than 0.5%.

The bottom product from the azeotropic distillation column is dilute calcium chloride solution with some HCl content. The dilute CaCl2 solution is concentrated in the evaporator and the re-concentrated CaCl2 solution is recycled to the azeotropic distillation column by pump. Vapour liquid separator is provided for separation of acidic water vapour and concentrated Calcium Chloride.

The vapour from the evaporation process consists of water and expected to contain approx than 2-3% HCl. This water vapour is condensed in the heat exchanger prior to discharge. Acidic condensate is sent to the effluent through barometric seal pot.

All the wetted parts of the system are fabricated from corrosion resistant materials (Glass /PTFE) for the process conditions envisaged.