| 摘要 |
A process for concentrating or purifying H2SO4 comprises vaporising 80-93 wt.% H2SO4 optionally contaminated with organic compounds, to a concentration of 95-98 wt.% H2SO4 optionally with addition of oxidant. The H2SO4 is vaporised at 270-340 degrees C and 0.1-2 bar pressure (absolute) in apparatus having heat transfer surfaces made of (austenitic)-ferritic Fe alloys consisting of: (in wt.%): 13-32 Cr, 5-25 Ni, 4-9 Si, max. 0.07 C, max. 0.03 S, max. 0.03 P, max. 8 Mn, max. 3 Mo, max. 4 Co, max. 20 Co, max. 4 W, max. 2 Nb and Ta, and max. 0.2 N with a balance of Fe, with a structure having a delta -ferrite amount of 10-65%, or 10-12 Cr, 15.5-17.5 Ni, 5.7-6.5 Si, max. 0.06 C, max. 0.03 P, max. 0.03 S, max. 1.5 Mn, max. 0.15 Ti, max. 0.8 Zr, max. 0.2 N, max. 0.3 Mo, max. 0.01 B, max. 0.25 rare earth, max. 1 Mg, Al or Ca with a balance of Fe, or 8-16 Cr, 20-30 Ni, 6.5-7.4 Si, max. 0.03 C, max. 0.03 P, max. 0.01 S, max. 1 Mg, Al and Ca, with a balance Fe. |
