Ion-exchange counter-flow filters (FIPr)

Ion-exchange counter-flow filters (FIPr) are intended for use in water treatment and chemical water purification systems to obtain softened and demineralized water at central heating and power plants, boiler stations, and industrial plants.

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Filter description: The ion-exchange counter-flow filter (FIPr) is intended for elimination of hardness cations (Ca2+ and Mg2+) from the incoming flow in the process of sodium-hydrogen cycle as well as elimination of sulphate, chloride, and nitrate anions in the process of natural waters demineralization. Produced softened and demineralized water is usually used as make-up water for steam boilers (low, medium, high pressure steam generation), water boiler, heat supply system. Less often the water coming after ion-exchange cleaning is used in various industrial processes.

Ion-exchange counter-flow filters (FIPr)Ion-exchange counter-flow filters (FIPr)

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

 

Design description: The ion-exchange counter-flow filter (FIPr) consists of:
  • vessel;
  • inspection window;
  • top and bottom (in certain cases - intermediate) distribution assemblies;
  • two lateral and one or two mounting manhole hatches (depending on applied hold-down technology);
  • piping;
  • shut-off valves;
  • sampling station.

 

FIPr filter has cylindrical vessel made of welded sheet steel and equipped with welded elliptical pressed bottoms. Three supporting elements are welded to the lower bottom to enable filter mounting onto the foundation.

Top and bottom collection and distribution assemblies of "false bottom" type equipped with plastics or stainless slotted caps (FEL) are used for counter-flow filters with the mechanical hold-down technology.

TheTop collection and distribution assembly equipped with the slotted radial pipes (or assembly of "cup-in-cup" type) is used for FIPr filters with the hydraulic hold-down technology. Furthermore, the ion-exchange counter-flow filter with hydraulic hold-down technology is equipped with intermediate collection and distribution assembly and horizontal bottom collection and distribution assembly of duplicating type.
 
Operation principle: FIPr filter cycle includes following stages:
  • softening or demineralization (filtration);
  • regeneration;
  • ion exchange resin backwash;
  • discharge of the primary permeate water before putting in the circuit.

 


 

 

FIPr filter operation cycle is finished when the rated normal breakthrough of cation (anion) exchange resins is detected, in other words, when ion-exchange capacity is exhausted.
 
 
FIPr filter principle of water softening (mechanical hold-down of ion exchange resin and upward regeneration)
 
Pressurized incoming clarified water is supplied to FIPr filter, uniformly distributed through the slotted caps of the top "false bottom", passes downwards through the inert material layer and then through the filtering material. Hardness cations are kept in the ion exchange resin beads, and Na cations move in the permeate water that is discharged through the lower "false bottom" from the vessel to the collecting receiver.

When the capacity of cation exchange resin is exhausted (determined by analytical monitoring of hardness cation breakthrough), the filter is stopped and switched to cation exchange resin regeneration stage (regeneration of ion exchange resin capacity). For regeneration stage the softened water is supplied to FIPr filter in upward direction to bring up and press ion exchange resin layer (2-5 minutes), then the ready-made regenerating solution (10-15% sodium chloride solution) is supplied and water flow for pressing is shut off. When certain volume of regeneration solution has been supplied, its supply is shut off and softened water comes to backwash cation exchange resin. The volume of backwash flow is stepwise decreased thus providing for layer-by-layer precipitation of the ion exchange resin in the filter. Pressing water, exhaust regeneration solution and backwash water are discharged to the drainage.
 
When the backwash is complete and cation exchange resin capacity is regenerated 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 treated water are achieved, FIPr filter is connected to the treated water receiver.
 
 
Principle of water softening by FIPr filter (mechanical hold-down of ion exchange resin and downward regeneration)

Pressurized incoming pretreated water is supplied to FIPr filter in upward direction, and then the water is uniformly distributed through the slotted caps of the lower "false bottom", brings up the entire ion exchange resin layer and presses it to the inert material layer that uniformly distributes the flow and hydraulic pressure across the entire surface of the top "false bottom". Hardness cations are kept in the ion exchange resin beads, and Na cations move in the permeate water that is discharged through the top "false bottom" from the vessel to the collecting receiver.

When the capacity of cation exchange resin is exhausted (determined by analytical monitoring of hardness cation breakthrough), the filter is stopped and switched to cation exchange resin regeneration stage (regeneration of ion exchange resin capacity). Regeneration stage begins after complete precipitation of ion exchange resin in the filter. The inert material is located above the cation exchange resin as an upper layer and pressed to the top collection and distribution assembly. The regenerating solution made from the softened water (10-15% sodium chloride solution) is supplied downwards. When certain volume of regeneration solution has been supplied, its supply is shut off and softened water comes to backwash cation exchange resin. Exhaust regeneration solution and backwash water are discharged to the drainage.

When the backwash is complete and cation exchange resin capacity is regenerated 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 treated water are achieved, FIPr filter is connected to the permeate water receiver.
 
Since it is impossible to perform loosening stage in the counter-flow filters with mechanical hold down of the ion exchange resin, so two requirements shall be met to achieve high efficiency of counter-flow filtration:
  1. observe the limits of suspended solids content in the incoming flow (not more than 2.0 mg/dm3);
  2. use hydraulic reloading and service tanks for periodic loosening of cation (anion) exchange resin. Frequency of the ion exchange resin loosening in the treated (filtered) water depends on the non-ionic contamination level of the incoming flow.
 
Principle of water softening by FIPr filter (hydraulic hold-down of ion exchange resin)
 
Incoming water under pressure is supplied to FIPr filter, passes upwards through the filtering material layer. Hardness cations are kept in the ion exchange resin beads, and Na cations move in the permeate water that is discharged through the bottom "false bottom" from the vessel to the collecting receiver.
 
When the capacity of cation exchange resin of upper "blocking layer" is exhausted (determined by analytical monitoring of hardness cation breakthrough by sampling station located under the slotted caps of the intermediate distribution assembly), the filter is stopped and switched to cation exchange resin regeneration stage (regeneration of ion exchange resin capacity). To perform this stage inlet and outlet of FIPr filter are closed, softened water for loosening or ready-made regenerating solution (10% sodium chloride solution) is supplied upwards to intermediate collection and distribution assembly. When certain volume of regeneration solution has been supplied, its supply is shut off and softened water comes to backwash cation exchange resin. Exhaust regeneration solution and backwash water are discharged through the top collection and distribution assembly to the drainage. Intermediate (short) regeneration of the upper ion exchange layer allows eliminating its mechanical impurities and regenerating exchange capacity, therefore it allows achieving more efficient treatment of lower layers of ion exchange resin.
 
When the entire capacity of cation exchange resin is exhausted (determined by analytical monitoring of hardness cation breakthrough in the permeate water flow), the filter is stopped and switched to cation exchange resin regeneration stage (regeneration of the entire ion exchange resin capacity). The regeneration solution (10-15% sodium chloride solution) made in the softened water is supplied upwards through the bottom collection and distribution assembly, and then exhausted regeneration solution is discharged to drainage through the intermediate collection and distribution assembly. Some volume of regeneration or softened water is supplied to FIPr from above for hydraulic hold-down of entire ion exchange resin with further removal of the down coming flow to drainage through intermediate collection and distribution assembly. When certain volume of regeneration solution has been supplied, its supply is shut off and softened water comes to backwash the whole volume of cation exchange resin in downward direction. The backwash water is discharged to the drainage.
 
When the backwash is complete and cation exchange resin capacity is regenerated 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 treated water are achieved, FIPr filter is connected to the softened water receiver.
 
The upper third part of FIPr with the hydraulic hold-down of the ion exchange resin (from the intermediate to top collection and distribution assembly) is free and available to perform regular loosening and backwash of all ion exchange resin in the vessel without the use of additional tanks.
 
 
Advantages and disadvantages of presented ion exchange counter-flow technologies
 
Technology with mechanical hold-down of ion exchange resin shows that additional service tanks are required for FIPr filters to perform regular remote loosening and backwash of filtering medium to remove fines, debris, and accumulated suspended solids, as well as small amount of floating neutral (inert) filtering medium that help to remove ion exchange resin from top collection and distribution assembly.
 
Furthermore, the application of this technology is restricted by suspended solids content in the incoming flow (not more than 2.0 mg/dm3) that imposes strict requirements on the coming from the pretreatment stage.
 
Advantages: high performance with the same overall dimensions, ion exchange of higher quality, no need for the secondary exchanger for water final treatment, reagents consumption close to stoichiometric values, remarkable reduction of clean water amount used for in-plant use and significant reduction of waste water.
 
In its turn the technology of hydraulic hold-down of ion exchanger having the same performance advantages and reagents consumption does not require the additional service tanks to perform remote loosening, since this process is performed regularly inside the filter. Due to short loosening and regenerations of "blocking layer" the content of suspended solids in the incoming flow is less restrictive in terms of this technology application, besides there is a lower risk of untreated ion exchange resin areas appearance. One more advantage is that the parallel-flow filters could be retrofitted to the counter-flow ones without moving primary FIPa filter vessel from its position. Disadvantages of this technology are more complicated piping layout, increased number of shut-off valves, and necessity to mount the intermediate collection and distribution assembly. Only primary FIPa and FSU vessels are fit for retrofitting to FIPr filters with hydraulic hold-down of the ion exchange resin.
 
The loosening of ion exchange resin could be performed both inside the filter's vessel and outside (in the separate service tank) depending on applied technology of ion exchange resin hold-down. FIPr filter operation cycle is finished when the rated normal breakthrough of cation (anion) exchange resins is detected, in other words, when ion-exchange capacity is exhausted, or in case of inlet-outlet pressure differential is more than 0.3 Mpa.
 
 
Product line and specifications of ion exchange counter-count filters (FIPr)
 
Filter type
Diameter, mm
Capacity,
m3/hour
Operating pressure, MPa
Height, mm
Filter weight, kg
FIPr 1,0-0,6
 1000
32
 0,6
3720
1650
FIPr 1,4-0,6
 1400
62
 0,6
4120
2600
FIPr 1,5-0,6
 1500
72
 0,6
4180
2800
FIPr 2,0-0,6
 2000
128
 0,6
4800
5100
FIPr 2,6-0,6
 2600
230
 0,6
5380
8100
FIPr 3,0-0,6
 3000
280
 0,6
5650
9650

 

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