Problem No. 55 How to clean heaters

Heat exchanger tubes in heaters in a urea plant such as the high pressure stripper and medium pressure and low pressure recirculation heaters typically suffer from process-side fouling. This fouling can be caused by oil and/or iron and chromium oxides. One obvious solution to remove this fouling is high pressure water jetting, but the fouling in the high pressure stripper can be so hard that this method does not work.

Stamicarbon together with VECOM, in the Netherlands, have developed a chemical cleaning method for cleaning CO₂ strippers, and NIIK, in Russia, has developed and successfully applies several cleaning methods for the removal of scale in heat exchangers in urea plants such as thermo-abrasive blasting, hydromechanical cleaning, high pressure hydro cleaning, vortex blasting cleaning, chemical cleaning (with orthophosphoric acid, and ultrasonic cleaning.