The use of cold elements of higher-grade steel or enamel coating will reduce the effect of corrosion.
Hot and fouling
With tough ash particles in the hot end elements, the profiles are such selected so as to reduce fouling and facilitate easier cleaning.
Cold End Fouling
Often due to inadequate ash in the flue gas not absorbing condensing acid. Answer could be closed profile elements.
Insufficient Heat Recovery
Heat recovery and boiler efficiency can be had by using higher efficiency elements and by use of unused space within the rotor.