Patent ID: 8168154

Claim:
A start-up method of a process for producing chlorine from hydrogen chloride comprising: a) producing a mixed gas containing said chlorine from said hydrogen chloride in a process system, wherein at start-up, the process system contains inert gas and air; b) producing a compressed mixed gas by introducing said mixed gas to an inlet of a compressor and compressing said mixed gas by said compressor; c) purifying said compressed mixed gas in a purifying column to separate said compressed mixed gas into chlorine and impurities by distillation, wherein the impurities include the inert gas and air present in the process system at start-up; d) recompressing said purified chlorine by introducing said purified chlorine to the inlet of said compressor and compressing said mixed gas and said purified chlorine to obtain a recompressed gas; e) passing the recompressed gas to step c) to obtain a purer chlorine; f) a measuring step of measuring a purity of said purer chlorine that is discharged from said purifying column, and g) if the purity of said purer chlorine is less than a prescribed purity, passing the purer chorine to step d) and if the purity of said purer chlorine is at or higher than the prescribed purity, the purer chlorine is recovered as the chlorine product.