Commercial Hydrochloric Acid is available in the market as 30% aqueous solution. But for certain applications e.g. bulk drug and pharmaceuticals, HCl is required in anhydrous state for critical reactions where moisture cannot be tolerated. Such users generate anhydrous HCl from commercial grade for their captive consumption.
METHOD
Several methods have been adopted by industries. But generation by Sulphuric Acid Route and Boiling Route are commonly practiced.
We offer Calcium Chloride Route also
| Route | Sulphuric Acid Route | Boiling Route |
|---|---|---|
| Working Principle | Hydrochloric acid is highly soluble in water but the solubility diminishes in presence of H2SO4 and at 70 to 75% H2SO4 concentration its solubility is negligible. Thus by adding (98%) commercial Sulphuric acid to commercial hydrochloric acid (30%) in proper ratio the entire HCl can be liberated in gaseous form leaving 75% H2SO4 as spent acid. | Aqueous hydrochloric acid forms a maximum boiling point o azeotrope at 110 C containing 20.24% HCl at atmospheric pressure. Thus by distilling commercial hydrochloric acid (30%) pure HCl gas can be generated and spent acid will contain over 20.24% HCl. |
| Process Outline | Metered quantities of commercial sulphuric acid hydrochloric acids are fed to the unit where they mix in the Mixing Zone. The gas generated forms a froth and enters the Generation Zone where while traveling through a bed gas is released which travels upwards through the Drying Zone. Here the gas comes in intimate contact with downward flow of 98% H2SO4. The dry gas leaving the unit passes through a rotameter. The spent liquor containing 70-75% H2SO4 passes through the Cooling Zone before being discharged | Metered quantity of commercial hydrochloric acid is preheated in a preheater by steam and fed to a fractionating column with steam as heating media in the reboiler. The vapours leaving the column are condensed with coolant as cooling water and chilled brine in stages.The relatively dry gas passes through a mist eliminator and then through a rotameter. The spent acid containing 22% HCl is cooled through a cooler and then discharged. |
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| Indicative Raw-material & Utilities for 20 kg/hr HCl |
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