COST REDUCTION THROUGH CREATIVE CHEMICAL TECHNOLOGY
Technical Data Sheet
ION EXCHANGE RESIN CLEANING
Much has been written on the fouling of ion exchange resins.
However, for the purpose of discussion of cleaning procedures, it is only
necessary to know the most common foulants of cation resins are iron, copper,
manganese and aluminum while for anion resins, colloidal silica and organics
pose the most problems. Once it has
been determined what the major cause of the fouling is and appropriate cleaning
chemicals selected, the actual cleaning procedures are quite similar.
Preparation for Cleaning
Prior to any cleaning operation, the resin must be
converted back to its exchange form (sodium or hydrogen for cation resins and
most commonly hydroxide for anion resins) in order to maximize the performance
of the cleaning chemicals. Therefore,
the units should be regenerated immediately prior to cleaning.
Also, where the units are typically regenerated at lower regenerant
dosages (i.e. 6-10 lbs. salt/ft.3 for sodium zeolite softeners) for
economy, if possible the regenerant strength should be increased to the maximum
recommended (i.e. 15 lbs. salt/ft.3) for this regeneration.
Once the unit is regenerated and isolated from the
system, it must be partially drained and the top handhole plate removed.
Then the predetermined amount of the cleaning chemical should be added
and then water added to bring the level to just above the resin bed (1" is
good). Do not drain the unit
until ready to start the cleaning as the resin must always remain in a moist
condition or it can be ruined.
An air lance should then be inserted into the resin bed
to provide agitation and good mixing of the chemicals and resin for cleaning.
It is recommended that a pipe be securely tied or welded to the air lance
pipe so that the lance cannot be inserted into the resin support bed which, if
sufficiently disturbed, could result in major resin losses into the system.
During the cleaning operation, the air lance should be moved frequently
to assure coverage of the entire resin bed.
Typically, the cleaning operation will require from 4-8 hours. When complete, remove the lance, fill the unit with water, replace the handhole cover and backwash thoroughly. Then double regenerate the unit and return it to service.
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