Raw or filtered water with total dissolved solids (TDS) needs to be removed for various process application. De-mineralisation or de-ionisation of water using Ion Exchange process is quite common in the industry and this can produce water having total dissolved solids less than 1 ppm.
“AquaTherm” Demineralisation plant exchange all cations and anions during Ion Exchange process,which consists of either twin bed or with mixed bed polisher. The charged resins exchanges H† ions with all Cations and OH? ions with all anions to de-ionise the water.The DM system needs regeneration with HCL acid and NaOH alkali after certain period based on the input load of Total dissolved solids. The system can be designed in various ways such as twin bed, Mixed bed, with De-gasser, Weak base anion etc. etc. based on the feed water analysis to reduce the operating cost .The system can be supplied in manual or auto mode.
- A pre-validated & pre-tested skid mounted solution!
- Complies and supersedes latest US,European & Indian Pharma standards for purified water generation and distribution!
- Designed & manufactured as per Pharma Engg. and Industrial standards!
- CGMP & GAMP compliance!
- Standardized product-fast track delivery-reduced time & compliance cost!
- Hot water sanitary(<80ºC) fully automatic or Manual DM Plant skid!
- All bought outs item from reputed suppliers across the globe!
- Sanitary Mild Steel Rubber lined or CPVC piping!
- All the Pressure Vessels are as per strict Industrial design standards!
- Reputed make piping and valves.
- All the Resins are from top most and reputed manufacturers across the globe.
- Flow Range:100 LPH to 1,00,000 LPH
- Material of Construction: Mild steel Rubberlined /FRP / CPVC
A Demineralisation Plant consists of two pressure vessels containing cation and anion exchange resins. Various types of ion exchange resins can be used for both the cation and the anion process, depending on the type of impurities in the water and what the final water is used for.
Typically, the cation resin operates in the hydrogen cycle. The cations in the water (i.e. calcium, magnesium and sodium) pass through the cation exchange resin where they are chemically exchanged for hydrogen ions.
The water then passes through the anion exchange resin where the anions (i.e. chloride, sulphate, nitrate and bicarbonate) are chemically exchanged for hydroxide ions.
The final water from this process consists essentially of hydrogen ions and hydroxide ions, which is the chemical composition of pure water.
The main considerations for demineralization operation are operating economics, quality and reliability of resin performance, and minimizing environmental costs. The primary variables in determining the operating economics are costs associated with regeneration, waste neutralization and disposal, as well as, resin replacement and disposal. The advent of uniform particle size (UPS) resin technology by resin manufacturers has brought about a paradigm shift in the performance and resulting economics of ion exchange resins.
As a leader in both Ion Exchange and Reverse Osmosis technologies we are able to offer its customers an unbiased product offering designed to optimize performance and economics.
Co-current Flow Regeneration
The resin contained in the pressure vessel has about 50% free space above the resin (known as resin-free board). This free space allows backwashing, removal of any entrained solids, re-classification of the resin bed and it relieves bed compaction.
Water and acid/caustic regeneration is carried out in a down-flow direction.
Counter-current Flow Regeneration
With counter-flow regeneration, the regenerant acid and caustic passes in the opposite direction to the service flow water.With counter-flow regeneration, the regenerant passes through the resin near to the outlet of the unit and, hence, counter-current flow regeneration has lower leakage to service than the co-current method.
Quality of the treated water from a DM water plant
The quality of the water depends on the type ofscheme used:
Cation -> Anion ->Polishing Mixed Bed
With this configuration, this type of plant should produce water of the following quality:
– Conductivity 0.1 µS/cm at 25°C
– Sodium 0.01 mg/l
– Reactive silica 0.02 mg/l
Cation->Anion (Counter-Current Regeneration)
With typical counter-flow regeneration, the average water quality is:
– Conductivity 0.5 to 1.0 µS/cm at 25°C
– Sodium 0.05 to 0.1 mg/l
– Reactive silica 0.025 mg/l
Cation->Anion (Co-Current Regeneration)
With typical co-current regeneration, the outlet quality will depend on the regenerant applied, resin employed and raw water quality.
– Conductivity 5 to 30 µS/cm at 25 C
– Sodium 0.5 to 3 mg/l
– Silica 0.1 to 0.3 mg/l
It is an insoluble matrix (or support structure) normally in the form of small (1–2 mm diameter) beads, usually white or yellowish, fabricated from an organic polymer substrate. The material has highly developed structure of pores on the surface of which are sites with easily trapped and released ions. The trapping of ions takes place only with simultaneous releasing of other ions; thus the process is called ion-exchange. There are multiple different types of ion-exchange resin which are fabricated to selectively prefer one or several different types of ions.
Most typical Ion-exchange resins are based on cross linked polystyrene. The required active groups can be introduced after polymerization, or substituted monomers can be used. For example, the cross linking is often achieved by adding 0.5-25% of divinylbenzene to styrene at the polymerization process. Non-cross linked polymers are used only rarely because they are less stable. Cross linking decreases ion- exchange capacity of the resin and prolongs the time needed to accomplish the ion exchange processes. Particle size also influences the resin parameters; smaller particles have larger outer surface, but cause larger head loss in the column processes.
There are four main types differing in their functional groups
- Strongly acidic (typically, sulfonic acid groups, e.g. sodium polystyrene sulfonate or polyAMPS)
- Strongly basic, (quaternary amino groups, for example, trimethylammonium groups, e.g. polyAPTAC)
- Weakly acidic (mostly, carboxylic acid groups)
- Weakly basic (primary, secondary, and/or ternary amino groups, e.g. polyethylene amine)
Advantages DM Plant are
- DM Plant can produce high-purity water comparable to distilled water for nearly every use.
- DM water is widely used for high-pressure boiler feed water and for many process waters.
- DM Plant come in a wide variety of sizes. Systems range from laboratory columns that produce only a few liters per hour to systems that produce thousands of liters per minute.
Limitations of DM Plant are
- Like other ion exchange systems, DM plants require filtered water in order to function efficiently.
- Resin foulants and degrading agents, such as iron and chlorine, should be avoided or removed prior to de mineralization.
- Anion resins are very susceptible to fouling and attack from the organic materials present in many surface water supplies.
- Some forms of silica, known as colloidal, or non-reactive, are not removed by a DM Plant.
- Hot,alkaline boiler water dissolves the colloidal material, forming simple silicates that are similar to those that enter the boiler in a soluble form. As such, they can form deposits on tube surfaces and volatilize into the steam
Treatment stages during Demineralisation of Water
- Filtration : The raw water which is to be de-mineralised should be well filtered. This should be passed through a Multigrade sand filter to remove suspended particles,dirt,mud etc. Then the filtered water is passed though Activated Carbon Filter to remove colour,odour and dissolved chlorine from the water. If the water does contain Dissolved Iron then Iron Removal filter becomes necessary to protect the Cation Exchange resins from fouling. As far as DM plant concern Mud and Chlorine are the critical factors for good performance.
It will be MS vertical pressure vessel or in FRP. Internally it will be fitted with inlet and outlet distributor and with top and bottom strainer plates. Externally the unit will be equipped with frontal pipe work and Diaphragm valves or single lever Multiport valve.
- Cation Removal : Filtered Water will then pass through the Strong acid Cation unit to remove all cations i.e Calcium , Magnesium & Sodium,potasium etc. in the water by means of Ion Exchange resins.The cation exchange resins are in H+ form. It will be Mild Steel vertical pressure vessel with internally Rubberlined or in FRP. Internally it will be fitted with inlet and outlet distributor and with top and bottom strainer plates. Externally the unit will be equipped with frontal pipe work and Diaphragm valves or single lever Multiport valve.Cation Exchanger is been regenerated with HCL acid by means of ejector.
- Degasser system : The de-cationised water then passed through the degassed water system to deduce the load of bicarbonates. This also reduces the load on anion exchanger.Degasification is a process of gas removal from Water. In water treatment either CO2 or O2 is removed from Water. Gases are present in the intermolecular spaces in the water. These need to be reoved. In CO2 removal, the basic principal is to expose these gases to atmosphere by spraying them. The water is pumped from the top of the DG tower & the water falls over a set of Pall Rings which splashes the water into fine droplets & the gas i.e. CO2 escapes into the atmosphere. It will be Mild Steel Rubber lined / FRP vertical tower with internal layers of pp pall rings rested on plate . Externally the unit will be equipped with degasser blower and Degassed water tank.
- Anion Removal : Degassed Water will then pass through the Strong base / Weak base Anion unit to remove all cations i.e. carbonates, bicarbonates , chlorides & Sulphates,nitrates etc. in the water by means of Ion Exchange resins.The type-II anion exchange resins are in OH- form. It will be Mild Steel vertical pressure vessel with internally Rubber lined or in FRP. Internally it will be fitted with inlet and outlet distributor and with top and bottom strainer plates. Externally the unit will be equipped with frontal pipe work and Diaphragm valves or single lever Multiport valve. Anion Exchanger is been regenerated with NaOH alkali by means of ejector.
- Mixed Bed Polisher : Partially demineralised water which is having conductivity in the range of 5mS/cm to 35mS/cm & pH 7.5 to 8.5 then passed through Mixed bed polisher to get conductivity less than 1mS/cm & pH 6.5 to 7.0. It consists of strong acid cation resin and anion resin type – I to remove all the slipped cations and anions in the preliminary stages. Further this is having great advantage of removing silica which is very harmful in case of boiler feed water. It will be Mild Steel vertical pressure vessel with internally Rubber lined or in FRP. Internally it will be fitted with inlet and outlet distributor and with top and bottom strainer plates. Externally the unit will be equipped with frontal pipe work and Diaphragm valves & ejectors.