Shiraz Petrochemical Company (SPC) operates a Stamicarbon CO2 stripping urea plant since 1983 with a design plant capacity of 1500 mtpd near Shiraz in I.R. Iran. In the beginning of 2003 SPC installed the first Safurex® stripper in the world after experience had been gained with high efficiency trays.
As Safurex® does not need oxygen for passivation and the high pressure carbamate condenser is made of BC.05 stainless steel, less oxygen is needed for passivation. This offered the opportunity to SPC to reduce the oxygen content in the CO2 from normally 0.6 vol% to 0.3 vol%.
Lowering the oxygen in a urea plant leads to numerous benefits such as:
The Low Oxygen Test at SPC demonstrated no increase in corrosion in the HP synthesis section. Process benefits were evident; increased reactor conversion, lower steam consumption in the HP Stripper and lower ammonia emission.
There are no limitations for the SPC plant to run the plant at 0.3 vol% oxygen.
Based on this result, Stamicarbon from now on specifies an oxygen content of 0.3 vol% in the CO2 feedstock as a standard in a Stamicarbon stripping plant when following pre-requisites are met:
The Low Oxygen Test at SPC is a milestone on the road to an entirely oxygen-free urea plant. If the complete synthesis section is fabricated in Safurex®, an oxygen free urea plant becomes possible.
The successful test was carried out in close and constructive co-operation with Shiraz Petrochemical Company and National Petrochemical Company, Research and Technology.
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