WATER_RESIN_1[1].ppt

7/28/2019 WATER_RESIN_1[1].ppt

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INTRODUCTIONPRESENTATION ON WATER AND RESIN.

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WATER IS PRECIOUS.

WE TREAT I T WITHSPECIAL CARE! !

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Water Water is most important raw material used

in industry.

It has good heat carrying capacity. It is auniversal solvent.

Natural water is seldom pure.

Water gets contaminated due to contact withair, soil or industrial effluent.

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WaterSourcesSurface : River, Creek, Pond &

Lake

Ground : Deep and shallow

wells, spring & mine

Sea : -

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Major Impurities of Water

Non ionic & undissolved

Turbidity, silt, mud, dirt

& other suspendedmatters. Colour, organicmatter, colloidal silica,micro-organisms,

plankton, bacteria, oil andcorrosion products.

Gaseous

Carbon dioxide,

hydrogen sulphide,ammonia, methane,oxygen, chlorine, etc.

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Impurities of Water

Generally water is not suitable for any usewithout some treatment.

Impurities present are harmful dependingupon

Nature, source and amount present

End use of the water. Tolerance limits for various industries.

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Major Impurities of WaterIonic & Dissolved

CATIONIC

Calcium

Magnesium

SodiumPotassium

ammonium

Iron

Manganese etc.

ANIONIC

Bircarbonate

Carbonate

HydroxideSulphate

Chloride

Phosphate

Silica & Organic matter

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Water Analysis

The chemical examination of water is veryimportant for :

Selecting suitable water supply Selecting proper treatment scheme

Designing the plant

Trouble shooting

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Units for reporting Water Analysis

1. ppm as ions or mg/lit

2. Equivalent per million (epm)

epm = ppm

eq.wt. of ion3. ppm as CaCO3

= ppm as ion x 50

eq.wt. of ion

4. Grains per gallon as CaCO3= ppm as CaCO3

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Some terms in water analysis

WATER SAMPLING.

Turbidity : It is finely divided suspended matter,clay

silt and/or organic matter.

Conductivity :The ability of a solution to carry

electric current. Measured as micro mhos/cms.

pH :The scale for expressing acidity oralkalinity

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Some terms in water analysis(Contd...)

Alkalinity

The total of bicarbonate, carbonate andhydroxide alkalinity

Equivalent Mineral Acidity (EMA)Chlorides, sulphates and nitrates associatedwith cations

Hardness :Sum of Calcium and Magnesium.Other

divalent or trivalent cations such as Iron,Barium, 15/59


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Total cation.

Total hardness + Sodium + Potassium.

Total anion.

EMA + Silica + CO2

Residual Chlorine

The amount of free chlorine after satisfying

chlorine demand (usually 0.1 to 0.5 ppm)Total Dissolved Solids (TDS)

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Total Suspended Solids (TSS)

The solids which can be filtered off.

Silica

It is soluble silica or reactive silica

Colloidal Silica :

The non - reactive silica

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Chemical Oxygen Demand (COD)

The amount of oxygen consumed for oxidising

organic and oxidisable inorganic matter.

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Water Treatment

The basic water treatment processes arelimited.

Combination and variation of these areused to treat water for desired end use.

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Treatment for Non - IonicImpurities

Gravity settling

Filteration

Different Media :- Sand, Anthracite

- Active Carbon

- Polymer Bead

- Multimedia Filters

- Iron Removal Filters20/59


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Treatment for Non - IonicImpurities

Water pretreatment.

Chemical Coagulation

Inorganic Coagulant :- Alum, Iron Salts, etc.

Organic flocculant :

- Cationic, Anionic, Nonionic, Polyelectrolyte

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Treatment for Dissolved IonicImpurities

Chemical Precipitation

Hardness and alkalinity removal by lime sodaprocess (hot or cold)

Iron removal

Ion Exchange Technique

Membrane Technique

ElectrodialysisReverse Osmosis

Evaporation22/59


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Ion Exchange

Ion exchange is a reversible process. The ionsexchanged with stoichiometrically equivalent

amounts of ions of the same sign.After the ion exchange, the exchanger materialcan be brought back to original form by

suitable reaction, called regeneration.

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Advantages of Ion - Exchange

Technique Ambient temperature operation

Instantaneous treated water

Take care of fluctuation of load

Easy waste disposal

Cheaper to operate

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Application of Ion Exchange in WaterTreatment

Water softening

Partial demineralization

Demineralization (with or without silica removal)

Mixed bed polisher

Condensate Polishing. Heavy metal recovery.

Special application

Alkalinity reduction

Sulfate removal

Nitrate removal

Fluoride removal 25/59


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Major applications of IonExchange Resins

Water treatment

Purification and decolourisation of sugar

Purification and recovery of drugs, vitamins,amino acids, etc.

Purification of DMF, Glyoxal, Caprolactum.

Recovery of metals like Thorium, Uranium,

Gold Silver, etc.

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Catalyst in esterification, condensation, etc.

In medicines for tablet disintegration, toxicremoval as antacids.

In water analysis

Purification of brine.

Removing hazardous constituants from

industrial effluents.

Major applications of IonExchange Resins (Contd...)

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Ion Exchangers

Insoluble solid material carrying exchangeable

cations or anions

WAC SAC

Cation Exchange

WBA

Type I Type II

SBA

Anion Exchange

Ion Exchange Resins

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Properties of Ion Exchange Resins

Particle Size :

Purely hydraulic and kinetic influence on the ionexchange process. 0.3 - 1.2 mm size is satisfactory

for industrial applications.

Moisture Content :

It is bound water related to cross linking. About

45 - 55 depending on type of resin. Givesvaluable information on resin under use

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Properties of Ion Exchange Resins(Contd...)

Density :

Ion exchange resins are sold on volume basis, hencedensity measurement is necessary. Density differenceof cation and anion exchange resins is used for MB

operations.

Porosity :

Related to degree of cross linking, influences capacity &

selectivity. Functional groups are present throughoutthe resin body. Pores provides path for exchanging &exchanged ions. Pores can be micro or macro in size.

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Cross linking :

Influences capacity, moisture and swelling

Higher cross linking :Less moisture and swelling. Hard and brittle.

More hemispherical and oxidation resistance.

Less exchange rate

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Lower Cross Linking :

More moisture and swelling. Soft and

mechanically weak. Less chemical and oxidation resistance.

More exchange rate

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Swelling :

It is volume change due to change in

surrounding medium. Depends upon medium, resin matrix.

Ionic group present and type of counter

ions

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Total Exchange Capacity :

It is the capacity obtained from the total quantityof counter ions that is capable of exchange per

unit weight or volume of either dry or swollenresin

Operating Capacity :

The capacity that could be realised in a columnunder a set of selected conditions.

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Kinetics (speed of exchange reaction) :

It is influenced by cross linking, functional groups,

particle size, solvent and temperature.Stability :

During service and regeneration, resin is subjectedto expansion and contraction. Oxidising agents

attack the resin. There is mechanical attrition. Allthese influence resin life and economics ofoperation 35/59


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Selectivity

At low concentration in aquous medium and atordinary temperture -

The exchange potential increased with increasing

valence.Na+ < Ca++ < Al+++ < Th++++

If valence is constant, exchange potential increaseswith increase in atomic number.

Li < Na < K < Rb < Cs

Mg < Ca < Sr < Ba

F < Cl < Br < I 36/59


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Selectivity (Contd...)

Softening

Ca ) HCO3 (HCO3 (Ca) Cl +R - Na Na (Cl + R (

Mg) SO4 (SO4 (Mg

Regeneration :

Ca ) Ca)

) R + NaCl Na - R + ) ClMg) Mg)

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Partial Demineralization

By Split Stream (Softener + Dealkalizer) (Whenalkalinity is high and hardness is permanent.)

Strong Acid Cation Exchanger in H+ form :

Ca ) HCO3 Ca) (HCO3Mg ) Cl + H - R Mg) R+H (Cl

Na ) SO4 Na) (SO4

Strong Acid Cation Exchanger in Na+ form :

Ca ) HCO3 Ca) (HCO3

Mg ) Cl + Na - R Mg) R+Na (Cl

Na ) SO4 Na) (SO4 39/59


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Partial Demineralization (Contd...)

By WAC (when Alk. high & TH < Alk)

Ca ) ( Ca

Mg ) HCO3 + R - H R ( Mg + H2CO3Na ) ( Na

H2CO3 H2O + CO2

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Ion Exchange Resin - Properties

SAC :

pH range 0 - 14

Excellent physical & chemical stability

Swelling Na+ H+ 7%

H+ form used in DM process and MB

Reg. by 4-8% HCl or 1.5 - 5% H2SO4 (*)

Max op. temperature 120 C (250 8F)

(*) Regeneration is stepwise NA+ form used in softening process

Reg by 5 - 15% NaCl solution

Max op. temperature 140 C (2808F) 41/59


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Ion Exchange Resin - Properties(Contd...)

WAC : High exchange capacity

Excellent physical & chemical stability

pH range 5 - 14

Reg. by 2 - 4% HCl or 0.7 to 4% H2SO4 (*)

(*) Regeneration is stepwise

High regeneration efficiency Regeneration by 120% of stoichiometric qty

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WAC (Contd..)

Can be regenerated thoroughfare

Higher selectivity for divalent cations. Hence

cannot be regenerated directly by salt Takes cations associated with alkalinity. Hence

used for dealkalizing.

Max. op. temp. 100 C (212 F)

Swelling H+ Na+ 100%

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WBA : No salt splitting capacity in OH- form.

Can take anions only associated with strong acids.

High reg. efficiency. Reg. by 120% of stoichiometric qty.

Reg. by 1-5% NaOH

Can be regenerated thoroughfare

High operating capacity. pH range 0 - 9 Max. op. temperature 80 C

Swelling OH- Cl- 20%44/59

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SBA - Type I and Type II : Used for DM process and MB

Can split salts.

Reg. con. 4 - 8% NaOH

Swelling Cl- OH- 9%

Max op. temp 60 C (140 F) for type II

80 C (175 F) for type I Both the types can removal all anions

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SBA - Type I and Type II : Type II has high operating capacity

More susceptible to oxidation

Loosing of SBC is bit faster Regenerate some what more easily

Type I has better thermal and oxidativestability, maintain SBC for a longer period

Type I has better resistance to organic foulingthan Type II

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Demineralization

Strong Acid Cation Exchanger :

Ca ) HCO3 Ca) (HCO3

Mg) Cl + R - H Mg) R+H (Cl

Na ) SO4 Na) (SO4

Anion Exchanger :

(HCO3 (HCO3

H (Cl + R - OH R - (Cl +H2O(SO4 (SO4

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Regeneration Process

The process to bring back the exhaustedresin to original or usable form isregeneration.

The reaction is opposite to service reaction.

There are two methods for regeneration co-current and counter current method.

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Back Washing

Back washing is done for :

Loosening the bed

Re-classifying the bedTo remove dirt and filtered matter

To separate resin in MB

By back washing, more uniform distribution offluid is obtained in subsequent down-flowoperation.

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Back Washing

Pressing water (*) in upward direction toexpand the bed to about 50%.

(*) Raw water for SAC.Decationised (and degassed) waterfor SBA.

SBA outlet for MB

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Regeneration (Injection)

According to the resin by HCl, H2SO4 or NaOH, themajor factors affecting the degree of regeneration are:

Composition of the exhausted bed Flow rate

Contact time

Temperature

Purity of regenerant Conc. of regenerant

Amount of regenerant applied (Reg. level) 51/59


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Slow Rinse

It is extended regeneration. Hence atregeneration flow rate generally by 2 BV ofwater

Fast Rinse :

To remove traces of regenerant. Done at

service flow rate.

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Counter Current Regeneration

To minimise leakage and get better qualityeffluent

No frequent back wash given.

Provision is made to avoid fluidizing of the bedand then regenerant is passed in oppositedirection of service

Back wash is given only when necessary but

followed by double regeneration

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Fouling of Ion Exchange Resins


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g f gIt is covering of exchange sites and / or

obstructing ion exchange process.

Major Foulants :

Turbidity and mud

Oil & grease. Iron & Calcium.

Microbiological &Organic fouling.

Silica fouling. Oxidation due to Cl2.

Thermal degradation -- Variation in temperature.54/59


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Prevention is better than cure !!!

Many a times fouled resin cannot becompletely cured.

Fouling of resin can be treated by differentmethods according to the nature of foulants.

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Trouble Shooting

Major causes in general for less OBR :

Insufficient regeneration

Increased load

Over running in previous run

Fouling

Resin loss (quantity & quality)

Malfunctioning of up-stream unit/s Excessive rinsing

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Trouble Shooting

Major causes in general for poor quality :

Mechanical problem

Chemical precipitation, silica precipitation. Improper separation and improper mixing

(MB)

Wrong or misleading analysis hence apparent

poor quality

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R i S li


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Resin Sampling

Sample should be taken from the entire length ofcolumn

Label should indicate the source, date ofcollection and type of resin

Sample quantity should be sufficient for differenttests. About 500 ml. for one type and 1000 ml for

MB is sufficient

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Resin commissioning.

Cleaning & inspection of vessel.

Column testing or hydrotest of vessel

Checking pressure drop with & withoutresin.

Resin charging in vessel

Backwash & checking resin bed height.

Conditioning of resin before use. Doubleregeneration.

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Resin testing.

WATER_RESIN_1[1].ppt

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