Problem No. 10: High CO₂ content in liquid outlet of a high pressure CO₂ stripper in urea synthesis

It is well known that the high pressure CO₂ stripper efficiency in a urea plant is defined by the ammonia content in the liquid bottom outlet. The ratio NH₃/CO₂ in the bottom outlet is determined by equilibrium equations. Problems have been experienced with a relatively high CO₂ content. Several possible causes are explored. One cause could be that CO₂ slips through with the liquid bottom outlet due to a defective level measurement in the stripper bottom. Measuring the liquid level is not an easy task due to the corrosive nature and the risk of crystallisation. Sometimes a delta-P level transmitter is applied with flushes in its legs, but this is not a reliable option. Radioactive level measurements are often used but still safety risks, complicated calibrating procedures, limited lifetimes and maintenance costs are significant concerns. The radar level measurement developed by Stamicarbon offers a new reliable solution.

Mr Joko Raharjo of PT Petrokimia Gresik in Indonesia introduces an interesting topic to the round table: