Ion mixed-bed filters (FISD)

Ion-exchange mixed-bed filters (FISD) are intended for use in water demineralization and condensate-treatment facilities at the electric power stations. Water filtration is performed trough the layer of specific resin bed consisting of cation and anion exchange resins.

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Filter description: Ion exchange mixed-bed filters (FISD) are designed for removal of Na+, К+ cations and hydrated silica acid anions from the incoming water as a final step of water demineralization process. Produced highly demineralized water is usually used as make-up water for steam boilers (medium and high pressure steam generation). Ion exchange mixed-bed filters are also used for post-treatment of turbine condensate. The filter is filled with a rated amount of mixed bed cation and anion resins. Water passed through a fine ion-exchange treatment is commonly used in various industrial processes where large amounts of super-clean water are required. One ion exchange mixed-bed filter may replace two Н- and ОН ion-exchange filters installed in series.

Ion mixed-bed filters (FISD)Ion mixed-bed filters (FISD)

Natural and human-made ion exchange resins (cation exchange resins and anion exchange resins) are used as the filtering medium in the ion exchange filters.

 

Design description: Ion exchange mixed-bed filters (FISD) consist of

  • vessel;
  • inspection windows;
  • top and bottom distribution assemblies;
  • piping;
  • shut-off valves;
  • sampling station.

 

FISD filter has cylindrical vessel made of welded sheet steel and equipped with welded elliptical pressed bottoms. The lower bottom has three welded legs to mount the filter on a foundation.

Upper and lower bottoms have centrally welded flanges for external connection of piping and internal connection of bottom and top collection and distribution assemblies.

For FISDNr filters an intermediate drainage-distributor made of stainless steel is provided to separate and regenerate the ion-exchange resin.
 
 
Operation principle: FISD filter cycle includes the following stages:
  • water demineralization (filtration);
  • loosening of the cation-anion bed;
  • regeneration (internal or external);
  • backwash;
  • mixing of ion-exchange bed;
  • discharge of the primary permeate water before it is put in the circuit.

 

Operation principle of FISDVr


Incoming pressurized flow is fed into the upper collection and distribution assembly of the filter, spreads evenly and passes through the mixed bed resins downwards. Na+, K+ cations and anions of hydrated silica acid remain in the material beads, thus, providing highly demineralized permeate water, that is discharged from the filter through the upper collection and distribution assembly into the collecting receiver.

 

Loosening (separation) of ion exchange resins is carried out upwards. The process of cation and anion exchange resins separation can be monitored through the inspection window of the filter. The regeneration of ion exchange resins using alkali and acid solutions can be carried out simultaneously or one by one. The backwash of ion exchange resins is performed with highly demineralized water in the direction of regeneration solutions flow. Upon completion of backwash the ion resins are mixed using compressed air. When the backwash and mixing are complete, the filter is put in operation or kept in standby mode. Right after the filter is put in operation the first volume of permeate water is discharged to the drainage for analytical monitoring. When the set parameters of the highly demineralized water are achieved, FISDVr filter is connected to the permeate water receiver.

 

 

Principle of FISDNr filter operation


Filter cycle includes following stages: high demineralization, shutdown for regeneration, hydraulic reload of the ion exchange resin into the regeneration filter (FR), hydraulic reload of regenerated the ion exchange resin from the regeneration filter, mixing of ion exchange resin, and backwash. High demineralization (desilication) occurs when the incoming flow passes through a layer of the mixed of cation and anion exchange resins.

 

The hydraulic reload of the exhausted ion exchange resins into the regeneration filter is carried out by a water slurry with velocity of 0.5 m/s (one regeneration filter is used for a group of three FISDNr filters). The regenerated ion exchange resins are reloaded from the regeneration filter by water slurry. Then the ion exchange resins are mixed using compressed air. The backwash of the ion exchange resins is performed downwards with a highly demineralized water. Right after the filter is put in operation the first volume of permeate water is discharged to the drainage for analytical monitoring. When the set parameters of the treated water are achieved, FISDNr filter is connected to the permeate water receiver.


The operation cycle of FISD filter is finished when content of Na+, K+ cations and anions of hydrated silica acid in the permeate water is close to the permissible levels.

 

Product line and specifications of ion exchange mixed-bed filters (FISD)

 

Filter type
Diameter, mm
 Capacity,
m3/hour
Operating
pressure, MPa
Height, mm
Filter weight, kg
FISDNr 2,0-1,0
2000
300 
1,0
3800
3100 
FISDNr 2,6-1,0
2600
500
1,0
4250
4600
FISDNr 3,4-1,6 3400
900
1,6
4500 9500
FISDNr 2,0-1,0
2000
220
0,6
4850
4300
FISDNr 2,6-1,0 2600 380 0,6 5380 6400

 

 

Our filters are manufactured in compliance with TU 3113-003-04688393-05 "Water-treatment filters for heat and power plants and industrial energy sector", efficient from July 1st, 2005.

 

To learn more about FISD filters, please, phone us: +7 (8482) 20-83-61, 20-85-90 or write to our e-mail: info@teko-filter.ru.