Urea plant

Abstract

The invention relates to urea plant with a CO2 and NH3 feed, which comprises a purge line, characterized in that the purge line is connected with a fuel gas input line of a utility plant or an NH3 plant.

1 . A urea plant comprising a CO 2  and a NH 3  feed, which further comprises a purge line, wherein the purge line is connected with a fuel gas input line of a utility plant or an NH 3  plant. 
     
     
         2 . A urea plant according to  claim 1 , wherein the purge gas contains oxygen at a concentration in the range of 0-10 mol %. 
     
     
         3 . A urea plant according to  claim 1 , further comprising synthesis equipment and synthesis piping wherein material used for the synthesis equipment and synthesis piping a duplex ferritic-austenitic contains, in % by weight:
 0-0.05 C;   0-0.8 Si;   0.3-4 Mn;   28-35 Cr;   3-10 Ni;   1.0-4.0 Mo;   0.2-0.6 N;   0-1.0 Cu;   0-2.0 W;   0-0.010 S;   0-0.2 Ce,   the remainder being Fe and normally occurring impurities and additives, having a ferrite content 30-70% by volume.   
     
     
         4 . A urea plant according to  claim 1 , wherein the oxygen concentration in the purge gas is in the range 0-1 mol %. 
     
     
         5 . A urea plant according to  claim 1 , wherein oxygen is essentially absent in the purge gas. 
     
     
         6 . A urea plant according to  claim 1 , wherein the purge stream is directed to the reformer section in an ammonia plant. 
     
     
         7 . A urea plant according to  claim 1 , wherein the purge stream is directed to the fuel gas supply of a steam boiler.