(Multi-effect) evaporators are used for the concentration of acids such as Phosphoric or Sulphuric Acid. The variety of dissolved components in the process acid leads to the formation of very hard and resistant deposits on the tube wall surfaces of the heat exchangers. Fouling on the tube-side of the heat exchangers in the acid concentration is a persistent operational problem. The deposits of fouling can create a significant resistance to heat transfer. The fouling requires regular cleaning and generates significant extra costs due to reduction of evaporation capacity, lost production, and maintenance and cleaning costs.
To prevent or limit the fouling of the heat exchangers that are used in the forced circulation evaporators for the acid concentration, the KLAREN-system
can be applied. The KLAREN-system, a self-cleaning fluidized bed heat exchanger, provides an ‘online’ and ‘inline’ continuous cleaning method to deal with fouling of shell and tube heat exchangers up to zero-fouling operation. The KLAREN-system uses cleaning particles that are carried and fluidized by the upward flow of the fouling liquid in the tubes and evenly distributed over all tubes.