ABSTRACT
The major market for ion exchange plants at that time, the power industry, was already well equipped to design and fabricate the tall steel pressure vessels required, since they were very similar to the designs used in making boilers. The original designs utilized coflow regeneration of the columns since downflow service and regeneration required virtually no modification to the basic equipment. In order to appreciate the differences between conventional and short-bed ion exchange technology, it is necessary to establish a basis of comparison. Most resins used industrially today are 0.3 to 1.2 mm in diameter with an effective size of 0.4 to 0.8 mm. Monodisperse resins with a uniform particle size within this range have seen increased use. Conventional designs normally allow at least 50% freeboard space over the settled resin bed to accommodate resin swelling and cleaning of the resin bed by backwash or fluidization.
