Process for purifying syngas

Abstract

The present invention relates to a process for the purification of raw syngas comprising the steps of (a) contacting the raw syngas with water to remove soot, resulting in a soot-rich waste water and a soot-lean syngas; (b) cooling the soot-lean syngas resulting from step (a) to a temperature in the range of from (20) to (50)° C.; and (c) contacting the cooled soot-lean syngas resulting from step (b) with water to remove HCN and NH3 resulting in clean syngas and HCN/NH3-rich waste water, wherein: (i) in step (a) the raw syngas is cooled below its dew point by its contact with water; (ii) the HCN/NH3-rich waste water resulting from step (c) is passed through at least one stripping column resulting in a clean water stream and a waste stream; and (iii) at least 50% (v/v) part of the clean water stream is recycled to step (c).

1 . Process for the purification of raw syngas comprising the steps of
 (a) contacting the raw syngas with water to remove soot, resulting in a soot-rich waste water and a soot-lean syngas;   (b) cooling the soot-lean syngas resulting from step (a) to a temperature in the range of from 20 to 50° C.; and   (c) contacting the cooled soot-lean syngas resulting from step (b) with water to remove HCN and NH3 resulting in clean syngas and HCN/NH3-rich waste water,   wherein:
 (i) in step (a) the raw syngas is cooled below its dew point by its contact with water; 
 (ii) the HCN/NH3-rich waste water resulting from step (c) is passed through at least one stripping column resulting in a clean water stream and a waste stream; and 
 (iii) at least 50% (v/v) part of the clean water stream is recycled to step (c). 
   
     
     
         2 . The process according to  claim 1 , wherein a first part of the soot-rich waste water resulting from step (a) is cooled and re-used in step (a). 
     
     
         3 . The process according to  claim 2 , wherein a second part of the soot-rich waste water is cleaned before further treatment. 
     
     
         4 . The process according to  claim 1 , wherein at most 90% (v/v) of the clean water stream obtained from the HCN/NH3-rich waste water stream is recycled to step (c). 
     
     
         5 . The process according to  claim 1 , wherein at most 10% (v/v) of the clean water stream obtained from the HCN/NH3-rich waste water stream is recycled to step (a).