19-05-2012, 03:34 PM
Resin Bed Regenerationin Water Treatment Processes
Water Treatment Processes.pdf (Size: 67.35 KB / Downloads: 108)
The illustration above shows how ABB multielectrode
conductivity systems are used to control/
monitor the concentration of chemicals used to
regenerate exhausted cation and anion resins. For
optimum regeneration it is necessary to monitor the
concentration of the regeneration chemicals.
Cation bed measuring points– Acid concentration
is monitored at the point 1 between the acid dilution
stage and the inlet to the cation resin bed.
Anion bed measuring points – Sodium Hydroxide
concentration is monitored at the point 2 between the
alkali dilution stage and the inlet to the anion resin
bed.
Mixed Bed Resin Regeneration – Monitoring points
will differ between WTP manufacturers, but both acid
and alkali concentrations should be monitored during
the regeneration process (not detailed in this guide).
Condensate Polishing Plant – As mixed bed resin
regeneration.
Why monitorconductivity in theregeneration process
The customer needs:
To control the strength of regeneration chemicals and regenerate exhausted
resin using the most efficient and economical method.
To control and monitor the regeneration process to ensure the resin is suitable
for use.
To ensure that the plant operates at the maximum efficiency.
To allow the plant to be maintained to specific standards.
Why useABB Instrumentation ?
ABB offer greater security at a lower cost by having:
• a worldwide network of companies and agents to ensure backup in most
areas,
• proven reliability – over 100 years of process instrumentation experience,
• over 40 years experience in on-line conductivity measurement,
• full installation, commissioning and routine servicing facilities available
(in the UK and some other countries this is covered by the
Assist ™ Customer Support Programme).
Comprehensive range of field-proven conductivity cells.
Both transmitters and cells are designed and manufactured by the
same company.
Transmitters are easily converted for use in low level conductivity applicationsand also pH and dissolved oxygen applications.
Model 4621/26 Series Multi-electrode Conductivity Transmitters and
Type 2241/2271 Conductivity Cells:
• 4621/26 multi-electrode transmitters have a direct readout in:
– sulphuric acid or hydrochloric acid
and
– sodium hydroxide,
• 4621/26 multi-electrode systems are equipped with a fouling alarm,
• 4621/26 systems offer true multi-range flexibility without recalibration,
• continuous on-line monitoring with comprehensive alarm/diagnostic
facilities as standard,
• multi-electrode based conductivity systems include a fouling alarm as
standard,
• well proven electronics, easy to read, backlit LCD 4-language display
(English, German, French, Spanish) can be customised with user friendly
software,
• NEMA4X IP66 (wall-mounted) enclosure suitable for installation in the mostdemanding environments.
• unique, highly accurate/repeatable cell constants (±1%) means that cellsare interchangeable without recalibration,
• sophisticated electronics package enables 100m separation between celland transmitter.
Cation Bed Regeneration
During the production of ultra pure water, cation resin, usually in the hydrogen
form, is used to remove cations such as Sodium (Na+), Calcium (Ca++),
Magnesium (Mn++) etc. from the process water and replace them with
hydrogen ions.
The process continues until the cation resin is exhausted and ceases to
function.
At this stage Hydrochloric or Sulphuric acid is passed through the exhausted
resin to recharge it with hydrogen ions and remove the cations which have
been extracted from the sample water. The regenerated resin is then put back
into service.
Anion Bed Regeneration
Anion resin (in the form of hydroxyl) is used to remove anions such as Chloride(Cl–), Sulphate (SO4– –), Silica (SiO2) etc. from the process water and replacethem with hydroxyl ions.
As with the cation resin, this process continues until the resin is exhaustedand ceases to function.
At this stage, the Chloride, Sulphate, Bisilicate and other anions are exchangedfor hydroxyl ions by regenerating the exhausted resin with Sodium Hydroxide.
The regenerated resin is put back into service.
Resin Regeneration
Efficient monitoring and controlling of the concentration of regeneration
chemicals helps optimise plant performance by reducing the frequency ofregeneration, therefore reducing downtime and saving on the cost of
regeneration chemicals.