[ Contrex ]
The Counter Current Regeneration
In regeneration of the ion exchange resin the use of a counterflow technique is normally preferred as far as performance and chemical consumption are concerned. In counterflow process it is essential that the bed stratification is not modified therefore when operating in an up-flow regeneration mode, the bed has to be held down to prevent mixing of the resin within the bed. At the same time, the need to remove any suspended matter retained by the bed in order to relieve compaction of the bed after a long period of operation by resin expansion and backwashing has also to be taken into account. Different methods to ret this result have been developed in the years by water treatment specialists.
Unidro Contrex System
Unidro proprietary regeneration system (Contrex) has a reliability proven in decades of successful experiences. The CONTREX process is a fixed bed system where the physical retention of the ion exchange resin bed in its position in the column is obtained by a compression layer placed above the resin bed. The compression mass is made of an inert granular material, properly graded, sufficiently compressible and with density lower than water.
The resin backwash in the Contrex system
Resin backwashing involves the expansion of the resin bed, which is obtained by feeding backwash water upflow though the resin bed at a suitable rate. Of course, a suitable freeboard must be available above the resin bed. With CONTREX system both internal and external regeneration of the resins are applicable.
When the freeboard available in the process vessel allows internal backwash, the compression mass is transferred to the twin vessel thus leaving the freeboard available for the resin expansion and backwash in place. Alternatively, the compression mass remains in the upper portion of the vessel and the resin is transferred to the backwash tank.