Dhandbad: the best materials I know are:
- Superaustenitic stainless steel 25%Cr-22%Ni-2%Mo (UNS No. 31050, DIN 1.4466). Oxygen injection is necessary to induce pasivation in SS surfaces. Normally, 0,5-0,8%vol O2 in the CO2 feed.
- Zirconium (R60702). Oxygen is not needed for the passivation...
Mcguire: if the chart which you refer is that of A. J. Sedriks, "Corrosion of Stainless Steels", 1st. edition, Wiley&Sons (ca. 1979), p. 250, figure 10-10, this graph is for pressure range 12-34 bar. The high pressure loop of the urea plant works at pressure in the range 150-200 bar...
Mcguire: The commercial synthesis of urea involves the combination of liquid ammonia and gaseous carbon dioxide in a reactor at high pressure (150-200 bar) and high temperature (180-190°C) to form ammonium carbamate, urea and water. Modern energy-efficient processes foresee the decomposition of...
I am looking for information about the effect of the presence of H2S in CO2 gas feed in urea plants. Specifically, the value at what the H2S content should be lowered to avoid corrosion problems in the urea reactor, stripper, carbamate condensator, etc. Does anyone have information about this...
