CHARACTERISTICS OF WATER :WATER FOR INDUSTRIAL APPLICATIONS

CHARACTERISTICS OF WATER

            PHYSICAL PROPERTIES:

*DENSITY - 1.0 at 4oC

*Specific Heat - 4.18 Kj/kg   at 0oC

*Latent Heat - Fusion 79 kcal/kg

*Latent Heat - Vaporization 539 kcal/kg

*Viscosity 1.797 mPa.s at 0oC

*Surface Tension 75.60 dynes/cm

*Osmotic Pressure

                        p = DCRT

            p : Osmotic Pressure in Pa

         DC : Difference in Concentration in mol/m3

           R : Constant of Ideal gases 8.314 J/mol/K

    

   

IMPURITIES OF WATER

*BACTERIA & VIRUSES

*MICRO-ORGANISMS

*TURBIDITY

*COLOUR

*MINERALIZATION

*METALLIC

*DISSOLVED GASES

*AMMONIA

*ORGANIC MATTER

*POLLUTANTS

SOURCES OF WATER FOR INDUSTRIAL APPLICATIONS

*RIVER

*SEA

*PONDS

*LAKES

*IRRIGATION CANALS

*BOREWELLS

*RECYCLED WATER

*RESERVOIRS

*RECYCLED EFFLUENTS                   

APPLICATIONS OF WATER  IN POWER PLANTS

*COOLING OF CONDENSATE

*AUXILIARY COOLING

*BOILER WATER

*ASH HANDLING WATER

*COAL DUST SUPPRESSION WATER

*WASHING

*DRINKING

*SANITATION

*FIRE WATER

*SERVICE WATER

*HVAC SYSTEM                                                

                MAKE - UP WATER TREATMENTS

*CLARIFICATION - ALUM, PEs, PAC

*FILTERATION

*ULTRAFILTERATION

*NANOFILTERATION

*REVERSE OSMOSIS

*ACTIVATED CHARCOAL

*SOFTENING - LIME, ION EXCHANGE

*ACID TREATMENT

*INHIBITORS

*OXYGEN REMOVAL

*BIOCIDE ADDITION                       

*

EFFECT OF CLARIFICATION PROCESS

                ON CORROSION BEHAVIOUR OF COMPONENTS  

*

*ALUM REDUCES   pH,   INCREASES  SULPHATES

*INCREASED   CORROSION

*PAC - LESS  pH  REDUCTION,  LESS  CORROSION

*POSSIBLE  LESS  COST  

INCREASED ALUM  DOSING

  

*QUICK RELIEF FROM PROBLEM

*

*

*EXHAUSTING MACHINE AND CHEMICALS

*INCREASE IN IONIC LOAD ON EXCHANGERS

*FREQUENT BACKWASH OF FILTERS

*CARRYOVER OF FINE FLOCS OF Al(OH)3

        INTO CLARIFIED WATER

*FREQUENT DESLUDGING OPERATIONS

*DELICATE PLANT OPERATIONS

*DAMAGE CONCRETE STRUCTURES

*HIGH Al CAUSE MENTAL DISORDERS

                    

POLYELECTROLYTE DOSING

            

  

*DECREASE ALUM DOSING EVEN BY 50 %

*WORKS AT VERY LOW DOSAGES

*REDUCES SLUDGE VOLUME BY 40 - 50 %

*WORKS IN WIDE pH RANGE

*LIME ADDITION CAN BE STOPPED

*NON CORROSIVE

*NO INCREASE IN IONIC LOAD ON RESINS

*REDUCTION IN INDIRECT COST

*NON-TOXICITY TO HUMANS

*DETRIMENTAL EFFECT ON RESINS  

REVERSE OSMOSIS

           PURE WATER          WATER WITH

                                                                                SALTS

               

                OSMOTIC PRESSURE = DC x R X t

                DC = CONCENTRATION IN MOL/M3

REVERSE OSMOSIS

*IT IS A PRESSURE ACTIVATED PROCESS BY WHICH

 WATER FROM A HIGHLY CONCENTRATED SOLUTION

  PASSES THROUGH SEMI-PERMEABLE MEMBRANE

  LEAVING THE SOLUTES BEHIND.

*IT IS A CROSS-FLOW MEMBRANE PROCESS WHICH

  REMOVES ALMOST ALL ORGANIC COMPOUNDS

  AND 90 - 99 % OF ALL IONS.

*SOLUTE PASSAGE CHARACTERISTICS ARE

  DETERMINED BY AFFINITY AND SOLUBILITY

  PHENOMENA.

*AN RO UNIT PRECEDING DM FOUND TO REDUCE

  PRODUCTION COST OF WATER BY ABOVE 50 %.

MATERIALS OF MEMBRANE

MATERIAL OF MEMBRANE IS CRUCIAL TO AVOID FOULING :

*POLYSULPHONATE

*POLYACRYLATE

*POLYCARBONATE

*POLYAMIDE

*POLYOLEFIN

*POLYVINYLLIDINE FLUORIDE

ADVANTAGES OF REVERSE OSMOSIS

            

*CONTINUOUS OPERATION

*NO REGENERATION NEEDED

*CAN HANDLE WIDE RANGE OF TDS (700 - 60,000 ppm)

*LOW OPERATING COST COMPARED TO DM

*BULK STORAGE OF CHEMICALS (ACID AND ALKALI)

  NOT REQUIRED

*LESS FLOOR SPACE NEEDED FOR RO PLANT IN                       

  COMPARISON TO DM PLANT

*EASY OPERATION AND MAINTENANCE

*REDUCED EFFLUENT QUANTITY AND TREATMENT COST

*COST OF TREATED WATER IS ALMOST HALF COMPARED

  TO DM WATER.

TOPICS TO BE COVERED

            

*NEED FOR WATER TREATMENT

*CLARIFLOCULATION PROCESS

*CHLORINATION

*ALTERNATIVES TO CHLORINATION WITH SPECIFIC 

  DISCUSSION ON OZONATION

*REMOVAL OF COLLOIDAL SILICA AT PRETREATMENT

  STAGE

*REVERSE OSMOSIS

WHY PRETREATMENT

            

*INCREASING POLLUTION IN WATER RESOURCES

*INCREASING STRUCTURES BY REGULATORY BODIES ON  USE OF WATER RESOURCES

*FINE QUALITY REQUIREMENTS WITH INDUSTRIAL   GROWTH, IN PARTICULAR POWER GENERATION   TECHNOLOGY

*MORE AWARENESS IN PUBLIC

*ECONOMIC USE OF DEMINERALISERS/MEMBRANES

BOILER FEED WATER

            

A PERFECT WATER FOR BOILER FEED IS ONE    WHICH WILL NOT DEPOSIT ANY SCALE FORMING   SUBSTANCES, WILL NOT CORRODE METAL OF   BOILERS AND WILL NOT RESULT       IN PRIMING OR FOAMING.

COMMON IMPURITIES IN WATER

          AND THEIR EFFECTS IF USED FOR BOILER FEED

            

*SUSPENDED SOLIDS : PRIMING, FOAMING, SLUDGE OR

  SCALE

*SILICA : DEPOSITION ESPECIALLY ON TURBINE BLADES

*CARBONATES, BICARBONATES OF CALCIUM AND

  MAGNESIUM : DEPOSITION

*CHLORIDE AND SULPHATE : SCALE AND CORROSION

*FREE ACIDS : CORROSION

*CARBONATE AND BICARBONATE OF SODIUM :

  PRIMING, FOAMING, EMBRITTLEMENT

*OXYGEN, CARBONIC ACID :  CORROSION

*OILS, GREASES : DEPOSITION, FOAMING, PRIMING

*ORGANIC MATTER : CORROSION, FOAMING, PRIMING,

  DEPOSITION

PRE-TREATMENT

            

TO MAKE WATER FREE FROM ALL IMPURITIES THAT WILL ADVERSELY EFFECT THE FEED WATERCHEMISTRY AND FURTHER WATER PURIFICATION PROCESS.

*SUSPENDED SOLIDS

*ORGANIC MATTER

*COLLOIDAL PARTICLES

*NON REACTIVE SILICA

*COLOUR AND ODOUR

*EXCESS DISINFECTANTS

*EXCESSIVE DISSOLVED IRON

  & MANGANESE

CLARIFLOCULATION

REMOVAL OF SUSPENDED SOLIDS BY

*COAGULATION/FLOCULATION

*SETTLING

*SEPARATION

                       ACHIEVED THROUGH

*RETENTION TIME

*ADDING COAGULANT

*ADDING COAGULANT AID

*CREATING SUITABLE pH & ENVIRONMENT FOR

  PROPER COAGULATION/FLOCULATION/SETTLING.

CHEMICALS USED IN WATER  CLARIFLOCULATION

            

*ALUM/FERROUS SULPHATE/FERRIC SULPHATE, SODIUM

  ALUMINATE, PAC: AS COAGULANT

*ACTIVATED SILICA, POLY ELECTROLYTES: COAGULANT

  AID

*LIME, SODIUM CARBONATE: pH ADJUSTMENT

*BENTONITE : FLOC WEIGHTING AGENT

CHANGES IN WATER QUALITY

         BY ADDITION OF 1 PPM OF PRETREATMENT CHEMICALS

            

*ALUMINIUM SULPHATE : CHANGE IN ALKALINITY BY 

  -0.45, SULPHATE BY 0.45

*FERROUS SULPHATE : CHANGE IN ALKALINITY BY -0.36,

  SULPHATE BY 0.36

*FERRIC SULPHATE : ALKALINITY BY -0.75, SULPHATE BY

  0.75

*CHLORINE : ALKALINITY BY -1.4, CHLORIDE BY 1.4

*HYDRATED LIME : ALKALINITY BY 1.26, HARDNESS BY

  1.26

*SODA ASH : ALKALINITY BY 0.5

TIPS TO ACHIEVE BETTER    CLARIFLOCULATION

                    

*KEEP RETENTION TIME AS PER YOUR REQUIREMENT OF  WATER QUANTITY

*FOR ALUM, THE FLOCULATION pH is 5.5 - 7.5

  FOR FERRIC ALUM, pH 5.5 - 7.5

  FOR NON FERRIC ALUM, pH 5.5 - 6.2

*MAINTAIN PROPER MIXING RATES AT THE  CLARIFLOCULATORS.

*FOR EXTREME LOW TURBID WATERS, USE BENTONITE

  CLAY OR FUELLERS EARTH ALONGWITH COAGULANT IF

  NECESSARY/POSSIBLE GO FOR SLUDGE CIRCULATION

*CLARIFLOCULATION IMPROVES WITH TEMPERATURES

TIPS TO ACHIEVE BETTER                    

                        CLARIFLOCULATION

            

*MAINTAIN PROPER SLUDGE BLANKET

*WHEREVER POSSIBLE/NECESSARY GO FOR COAGULANT 

  AID INSTEAD OF EXCESS ALUM.

*SODIUM ALUMINATE, WHICH IS HIGHLY ALKALINE CAN

  BE USED ALONGWITH ALUM IN COAGULATION OF LOW

  pH WATERS

*USE PROPER QUANTITY OF WATER DISINFECTANTS FOR

  BETTER CLARIFLOCULATION

*GO FOR BETTER INSTRUMENTATION, IF POSSIBLE ON-

  LINE FOR CHECKING AND OPTIMISING PRETREATMENT.

*PURITY OF LIME AND ITS SHELF LIFE ARE CRUCIAL FOR

  PROPER CLARIFLOCULATION

*DO NOT LOOK PRETREATMENT AND DEMINERALISATION

  IN ISOLATION

CHLORINATION PROCESS

*DESTROYING THE ORGANIC MATTER (BOTH CHEMICAL, BIOLOGICAL) THROUGH OXIDATION USING CHLORINE.  

*Cl2  +  H2O                          HClO + HCl  (5<pH<10)

*HClO                    ClO- + H+ (pH>10)

PROBLEMS WITH CHLORINATION

            

*CHLORINE IS A POISONOUS GAS SUPPLIED IN  CYLINDERS/TONNERS

*CHLORINATED WATERS WITH EXCESS RESIDUAL  CHLORINE ARE HAZARDOUS TO PLANT AND ANIMAL  LIFE

*ASSOCIATED WITH PROBLEMS LIKE COPPER TUBE  LEAKS, CORROSION OF ASSOCIATED PIPINGS, etc.

*TO REMOVE EXCESS CHLORINE IN TREATED WATER, WE  HAVE TO USE ACTIVATED CARBON, SODIUM SULPHITE  DOSING RESULTING IN EXCESS O&M COST

PROBLEMS WITH CHLORINATION

            

*MANGANESE, IRON, H2S AND ORGANICS WITH  UNSATURATED LINKAGES INCREASE CHLORINE  DEMAND, MICROBIOLOGICAL DISINFECTION WILL BE  EFFECTIVE ONLY AFTER REMOVAL OF THESE IONS.

*EFFECT OF CHLORINE ON VIRUS IS VERY LITTLE

*PHENOL IN WATERS REACT WITH CHLORINE TO FORM  CHLOROPHENOLS HAVING BAD ODOR AND TASTE

*CHLORINATION MAY RESULT IN FORMATION OF TRI  HALO METHANES WHICH ARE TOXIC

*CHLORINATION INCREASES IONIC LOAD ON FURTHER  TREATMENT SYSTEMS

ALTERNATIVES TO CHLORINATION

            

*BLEACHING POWDER DOSING : SOLID, HAVING LESS

  AVAILABLE CHLORINE, CAUSING MORE SLUDGE AND

  EXCESS LOAD ON ION EXCHANGERS

*SODIUM HYPOCHLORIDE ADDITION : LIQUID, NOT COST

  EFFECTIVE FOR LARGE QUANTITIES OF WATER

*BROMINATION : SUITABLE FOR WATERS THAT HAVE pH

  7.5 OR GREATER AND EXCESS AMMONIA. MOST

  COMMONLY USED IS NaBr. EFFECTIVE AT A WIDER pH

  RANGE.

*CHLORINE DIOXIDE ADDITION : SUITABLE WHEN WATER

  CONTAINS EXCESS AMINES, EFFECTIVE IN pH RANGE OF

  8 - 11.

OZONATION

            

*GETTING IMPORTANCE IN EUROPEAN COUNTRIES AS

  ALTERNATIVE TO CHLORINE

*PREPARED AT DOSING SITE BY SILENT ELECTRIC

  DISCHARGE OF DRY AIR (WITH DEW POINT<-70oC), OR

  DRY OXYGEN (WITH DEW POINT<-60oC)THROUGH SERIES

  OF ELECTRODES AND AT A VOLTAGE OF 17.5 KV.

*OZONE GENERATORS WITH OUTPUT OF EVEN 10 % BY

  WEIGHT ARE AVAILABLE

*THERMAL DESTRUCTION AND CATALYTIC DESTRUCTION

  METHODS ARE AVAILABLE FOR DESTROYING EXCESS

  OZONE GASES

*

ADVANTAGES OF OZONE

            

*REMOVAL OF IRON AND MANGANESE CAN BE

  EFFECTIVELY DONE AT NEUTRAL pH. (WITH

*CHLORINATION pH ABOVE 9 IS NEEDED.

*REMOVAL OF COLLOIDS AND ORGANICS IS MORE

  EFFECTIVE WITH OZONE.

*POLYMERS AND ORGANIC MACRO MOLECULES IN

  WATER GET EASILY BROKEN INTO SMALLER ORGANIC

  ACIDS WITH PROPERTIES OF COAGULATANT AIDS. THIS

  REDUCES THE FLOCULATING AGENT CONSUMPTION

  DURING CLARIFLOCULATION

*RESPONSE OF OZONE ON ORGANIC CELLS EXCEEDS

  CHLORINE BY A FACTOR OF > 10.

ADVANTAGES OF OZONE

            

*CHLORINE ATTACKS ENZYMES THAT EFFECT CELL

  MULTIPLICATION WHILE OZONE RUPTURE CELL WALL

  MAKING IT VERY EFFECTIVE EVEN FOR VIRUS.

*NO ADDITION OF DISSOLVED SOLIDS AS LOAD TO

  FURTHER ION EXCHANGERS

*HEALTH HAZARDOUS NATURE COMPOUNDS ARE NOT

  FORMED

*NOT HAZARDOUS IN HANDLING

*OZONE IS EFFECTIVE AT ALL pH

*EFFECTIVE IN REDUCING FUNGI GROWTH

*OPERATING COST IS VERY LESS.

PROBLEMS WITH OZONE

            

* CAPITAL COST IS VERY HIGH

*

*GAS IS UNSTABLE

          TO BE PREPARED AT SITE ONLY

*

*MAINTENANCE OF RESIDUALS IS NOT POSSIBLE.

*

CHEMISTRY OF SILICA IN WATER

*REACTIVE FORM

*

*SILICON DI OXIDE DISSOLVED IN WATER RESULTING IN

  MONOSILICIC ACID

*

* SiO2 + 2H2O                      H4SiO4

*

*RESPONDS TO STANDARD SILICO MOLYBDATE TEST

*

*SUSPENDED PARTICLE FORM - SAND

CHEMISTRY OF SILICA IN WATER

*COLLOIDAL SILICA

*INSOLUBLE & INSEPARABLE

*NON-IONIC IN THE FORM OF

*SILICON POLYMERISED WITH SiO2

*SILICON LOOSELY BOUND WITH ORGANICS

*SILICON LOOSELY BOUND WITH INORGANICS

* (Al2O3/CaO)

*CHEMICALLY NON - REACTIVE

*C(SURFACE WATER > WELL WATER)

*CONC. VARIES WITH LOCATION AND SEASON.

WHAT HAPPENS WHEN COLLOIDAL

                                     SILICA ENTERS BOILER?

*RESPOND TO ALL CHEMICAL TESTS

*

*FORCE PRESSURE REDUCTIONS, GENERATION

  LOSSES.

*

*SEVERE BLOW DOWNS AND HEAT LOSSES.

*

*LONG START-UPs.

WHAT HAPPENS IF BOILERS ARE

                         OPERATED WITH HIGH SILICA

*GETS CARRIED OVER TO THE TURBINE.

*DEPOSITS ON VARIOUS STAGES OF TURBINE BLADES

  DURING STEAM EXPANSION.

*DEPOSITS ARE HARD TO REMOVE.

*CAUSE VIBRATIONS IN THE TURBINE.

*REDUCE OPERATING EFFICIENCY.

*REQUIRE TURBINE BLADE WASHING/SHUT DOWN

  FOR CLEANING.

INCREASED RETENTION TIME

UPs :

*NO EXCESS/ NEW CHEMICAL REQUIREMENT.

*EXISTING MACHINE.

DOWNs :

*REDUCED OUTPUT.

*NON-UTILISATION OF PT SYSTEM TO FULL CAPACITY

                    

                                PRECOAT/POWDEX PROCESS

UPs :

*EASY TO OPERATE.

DOWNs :

*OPERATION COST IS VERY HIGH.

*LESS SHELF-LIFE OF MATERIALS.