Pretreatment plant

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Pretreatment plant

  1. 1. 1
  2. 2. PRESENTATION FOR WATER PRE TREATMENT PART OF OPERATION TRAINING UPPER EGYPT ELECTRICTY PROD CO. & EGYPTIAN ELECTRICITY HOLDING COMPANY KURIEMAT POWER STATION I AT MOL (SHJ) – JUL. 2007 2
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  4. 4. RAW WATER TREATMENT WATER CHEMISTRY 4
  5. 5. RAW WATER TREATMENT - WATER CHEMISTRY WHAT IS WATER? COLOURLESS, ODOURLESS, TASTELESS LIQUID POLAR LIQUID HIGH DIELECTRIC CONSTANT (81 @ 17°C) EXTREMELY GOOD SOLVENT POWER WEAK ELECTROLYTE DENSITY OF 1.00 @ 4°C ALLOTROPIC FORMS: ICE(SOLID) & STEAM(GAS) 5
  6. 6. RAW WATER TREATMENT - WATER CHEMISTRY Chemical Formula HOH H + H2 O OH - (H2O)n 6
  7. 7. RAW WATER TREATMENT - WATER CHEMISTRY The Water Molecule H O H 104° 7
  8. 8. RAW WATER TREATMENT - WATER CHEMISTRY WATER COMPOSITION WATER FORMULA = H20 TWO HYDROGEN ATOMS, 104deg APART DIPOLAR - POSITIVE CHARGE ON HYDROGEN. NEGATIVE CHARGE ON OXYGEN • DUE TO HYDROGEN BOND HAS HIGH ENERGY CONTENT • HYDROGEN BOND CAUSES ICE TO EXPAND & CREATES SURFACE TENSION. • • • 8
  9. 9. RAW WATER TREATMENT - WATER CHEMISTRY The Water cycle Natural System 9
  10. 10. RAW WATER TREATMENT - WATER CHEMISTRY WATER IMPURITIES –1 –2 –3 SUSPENDED SOLIDS DISSOLVED SOLIDS DISSOLVED GASES 10
  11. 11. RAW WATER TREATMENT - WATER CHEMISTRY SUSPENDED SOLIDS: COMPOSITION • LARGE PARTICLES – GRIT, SAND, ORGANICS LARGER THAN 1 MICRON • SMALL PARTICLES - TURBIDITY DUE TO CLAY, SAND, SILT, ORGANICS ETC. 0.5 TO 1 MICRON • COLLIODAL PARTICLES - GENERALLY OF SILICA LESS THAN 1 MICRON 11
  12. 12. RAW WATER TREATMENT SUSPENDED SOLIDS: EFFECTS • SOLIDS PRESENT IN PROCESS USE CREATE VARIETY OF PROBLEMS. • FOULING OF ION EXCHANGE RESINS & RO. • DEPOSITS IN HEAT EXCHANGER TUBES AFFECTING HEAT TRANSFER & CAUSING CORROSION. • POTENTIAL FOR RADIATION EXPOSURE IN NUCLEAR SECONDARY SYSTEMS • INCREASED BOILER & COOLING TOWER BLOWDOWN 12
  13. 13. RAW WATER TREATMENT TREATMENT OF WATER IMPURITIES 13
  14. 14. RAW WATER TREATMENT RAW WATER TREAT MENT MAINLY COMPRISE OF REMOVAL OF SUSPENDED SOLIDS, COLOR, BIOLOGICAL CONTAMINATION, ETC. 14
  15. 15. RAW WATER TREATMENT MAIN PROCESSES: • CLARIFICATION – SETTLE OUT THOSE LARGER SUSPENDED PARTICLES THAT ARE READILY SETTLEABLE. – CONDITION SMALLER MAKING THEM FILTERABLE • FILTRATION • SLUDGE HANDLING • DISINFECTION 15
  16. 16. RAW WATER TREATMENT REMOVAL OF SUSPENDED SOLIDS: • LARGE PARTICLES – THESE CAN BE SETTLED IN SEDIMENTATION BASINS IN THE FORM OF RESERVOIR OR TANK. • SMALL PARTICLES – REMOVAL OF SMALL PARTICLES REQUIRE CLARIFICATION EQUIPMENT. 16
  17. 17. RAW WATER TREATMENT COAGULATION 17
  18. 18. RAW WATER TREATMENT CLARIFYING SYSTEM: COAGULATION • THE KEY TO CLARIFICATION IS THE ADDITION OF CHEMICALS TO AGGLOMERATE SMALL SUSPENDED SOLIDS SHORTENING THEIR SETTLEMENT TIME. • THE PRIMARY FACTOR IS ELECTRICAL CHARGE. ALL PARTICLES OF TURBIDITY & COLOR HAVE USUALLY NEGATIVE ELECTRICAL SURFACE CHARGE. 18
  19. 19. RAW WATER TREATMENT CLARIFYING SYSTEM: COAGULATION • THE SIGN OF PARTICLE ELECTRICAL CHARGE & MAGNITUDE ARE AFFECTED BY THE pH & IONIC CONTENT OF THE SURROUNDING WATER. • THIS (-VE ) CHARGE ATTRACTS A COMPACT LAYER OF OPPOSITE CHARGED IONS (COUNTER IONS) IN A VERY CLOSE FORM & MORE DIFFUSE LAYER FURTHER AWAY. • THE ABOVE LAYER COMBINATION CREATES ELECTROSTATIC POTENTIAL THAT REPELS OTHER SIMILAR CHARGED PARTICLES. 19
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  22. 22. RAW WATER TREATMENT CLARIFYING SYSTEM: COAGULATION • CHEMICALS CALLED COAGULANTS ARE ADDED TO BREAKDOWN THIS BARRIER BY INTRODUCING OPPOSITE (+VE) . • COAGULANTS ARE METALLIC SALTS THAT INTRODUCE +VE METAL IONS CARRYING TWO OR MORE ELECTRICAL CHARGES. • THIS INCREASES THE CONCENTRATION OF COUNTER IONS IN THE DIFFUSE LAYER THUS THE REPULSIVE FORCE IS REMOVED THAT ALLOWS THE PARTICLES TO COME IN CONTACT. 22
  23. 23. RAW WATER TREATMENT CLARIFYING SYSTEM: COAGULATION • ALUM (ALUMIMIUM SULPHATE IS THE MOST WIDELY USED COAGULANT) • IN ADDITION TO NEUTRALIZING THE ELECTROSTATIC BARRIER THEY REACT WITH ALAKLINITY OF THE WATER TO FORM A TOUGH ALUMINIUM HYDROXIDE “FLOC” WHICH IS STABLE OVER pH RANGE 5.7-7.5. • IRON SALTS LIKE FeCl3 PRECIPTATE HYDROXIDE FLOC OVER MUCH BROADER RANGE 5 TO 11 HENCE ARE USEFUL IN LIME SOFTENING PLANTS. 23
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  25. 25. RAW WATER TREATMENT CLARIFYING SYSTEM: COAGULATION • ALUM HYDROLIZING REACTION RELEASES SULPHURIC ACID THAT REACTS WITH ALKALINTY FORMING CaSO4 & CO2. • EACH ppm OF ALUM USED BRINGS DOWN THE ALKALINITY BY 0.45 ppm. THUS TO COUNTERACT THIS EFFECT 0.4 ppm OF LIME (90% CaO) PER ppm OF ALUM IS ADDED OR 0.5 ppm OF SODA ASH PER ppm OF ALUM. 25
  26. 26. RAW WATER TREATMENT CLARIFYING SYSTEM: COAGULATION • SODIUM ALUMINATE IS SLIGHTLY ALKALINE. USEFUL TO ADD WITH LOW Ph WATERS REDUCING THE CONSUMPTION OF LIME NEEDED FOR SOFTENING. • THE QUANTITY OF ANY COAGULANT IS ACTUALLY IS CLOSELY CONTROLLED TO GIVE THE OPTIMUM pH FOR BEST COAGULATION. 26
  27. 27. RAW WATER TREATMENT CLARIFYING SYSTEM:- COAGULATION • OPTIMUM DOSAGE OF CHEMICALS VARY WITH – SUSPENDED PARTICLE SIZE & CONCENTRATION – DETENTION TIME BEFORE COAGULATION – WATER TEMPERATURE – AMOUNT OF MIXING ETC. • IN VIEW OF THE ABOVE IT IS EXTREMLY DIFFICULT TO PREDICT THE DOSAGES. • IN PRACTICE IT IS BASED ON JAR TESTS ON THE WATER IN USE. 27
  28. 28. RAW WATER TREATMENT CLARIFYING SYSTEM:- COAGULATION • JAR TEST SHOULD BE RUN AT LEAST ONCE IN A MONTH OR WHENEVER THERE IS APPRCIABLE CHANGE IN WATER QUALITY. • AS GUIDE, THE UPPER 100 mm IN A SAMPLE SHOULD BECOME CLEAR IN 2-4 MINUTES. • WATER WITH LOW TURBIDITY MAY BE MORE DIFFICULT TO COAGULATE THAN THAT WITH HIGH TURBIDITY. 28
  29. 29. RAW WATER TREATMENT CLARIFYING SYSTEM:- COAGULATION Drive Motor ………….. …………. ………….. …………. ………….. ………….. …………. …………. ………….. …………. ………….. …………. ………….. …………. ………….. …………. ………….. …………. ………….. …………. ………….. …………. ………….. …………. ………….. …………. ………….. …………. …………. ………….. …………. ………….. ………….. Test Beakers JAR TEST 29
  30. 30. RAW WATER TREATMENT COAGULANT AIDS USE OF POLYMERS 30
  31. 31. RAW WATER TREATMENT CLARIFYING SYSTEM: USE OF POLYMERS • POLYMERS ARE USED TO ENHANCE COAGULATION BY GROWING FLOC SIZE. • THESE ARE POLYELCTROLYTES – SYNTHETIC ORGANIC POLYMERS OF HIGH MOLECULAR WEIGHTS CONTAINING CHEMICALS GROUPS THAT CAN INTERACT WITH SURFACE SITES ON COLLOIDAL PARTICLES. • THESE ACT WITH EXTREMELY HIGH SPEED ENLARGING THE FLOC SIZE THUS IMPROVING SETTLEMENT. 31
  32. 32. RAW WATER TREATMENT CLARIFYING SYSTEM: USE OF POLYMERS • POLYMERS ARE EITHER CATIONIC (+veLY CHARGED) OR ANIONIC (-veLY CHARGED) OR NONIONIC. • SLIGHTLY ANIONIC POLYMER ARE NORMALLY EFFECTIVE. ONCE AGAIN JAR TEST IS NEEDED TO MAKE THE BEST CHOICE. • SOMETIMES FOR LESS TURBID WATERS A CATIONIC POLYMER MAY ACT AS PRIMARY COAGULANT. 32
  33. 33. RAW WATER TREATMENT CLARIFYING SYSTEM: FLOCCULATION • FLOCCULATION IS SLOW STIRRING OF COAGULATED PARTICLES TO ENHANCE THE PARTICLE GROWTH • NORMAL RETENTION TIMES ARE 20 TO 30 MINUTES • FLOCCULATING TANKS CAN BE EXTERNAL OR INSIDE CLARIFIER 33
  34. 34. RAW WATER TREATMENT POLYMER AID ACTION Polymer molecule Particle in suspension Agglommerated solids 34
  35. 35. RAW WATER TREATMENT CLARIFYING EQUIPMENT 35
  36. 36. RAW WATER TREATMENT CLARIFYING SYSTEM: CLARIFYING EQUIPMENT THERE ARE NUMBER OF TYPES AND SHAPES A FEW MOST COMMONLY USED ARE: • CONVENTIONAL • SOLIDS CONTACT • SOILDS RECIRCULATION • TUBE SETTLLER • LEMELLA PLATE 36
  37. 37. RAW WATER TREATMENT CLARIFYING SYSTEM: TYPICAL SURFACE LOADING RATES (m3/h/m2) • CONVENTIONAL 1.2 -1.5 • SOLIDS CONTACT * 2.5 • SOILDS RECIRCULATION* 2.5 • TUBE SETTLLER 1.8 • LEMELLA PLATE (PROJECTED AREA) 1.8 * RELATIVE TO SETTLING TANK SURFACE AREA 37
  38. 38. RAW WATER TREATMENT CLARIFYING SYSTEM: TYPICAL SURFACE LOADING RATES (m3/h/m2) • CONVENTIONAL 1.2 -1.5 • SOLIDS CONTACT * 2.5 • SOILDS RECIRCULATION* 2.5 • TUBE SETTLLER 1.8 • LEMELLA PLATE (PROJECTED AREA) 1.8 * RELATIVE TO SETTLING TANK SURFACE AREA 38
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  44. 44. RAW WATER TREATMENT SOLIDS CONTACT/RECIRCULATING CLARIFIERS 44
  45. 45. RAW WATER TREATMENT CLARIFYING SYSTEM: SOLIDS RECIRCULATION CLARIFIERS • INDUSTRIAL CLARIFIERS EMPHASIZE ON SOLIDS CONTACT. • A NUMBER OF DESIGNS ARE AVAILABLE. ACCORDING TO LATEST DEVELOPMENTS SOLIDS RECIRCULATION TYPE ARE MOSTLY PREFERRED DESIGN. 45
  46. 46. RAW WATER TREATMENT CLARIFYING SYSTEM: SOLIDS RECIRCULATION CLARIFIERS • SOILD RECICULATION CLARIFIERS COMBINE MIXING, FLOCCULATION AND SETTLING IN ONE TANK. • INCOMING WATER IS MIXED WITH CHEMICALS & INTIMATE CONTACT WITH RECIRCULATING PRE FORMED SLUDGE IN A REACTION ZONE. • FROM REACTION ZONE PASSES TO DETENTION ZONE WHERE GENTLE MIXING ENHANCES THE FORMATION OF FLOCS. 46
  47. 47. RAW WATER TREATMENT CLARIFYING SYSTEM: SOLIDS RECIRCULATION CLARIFIERS • THE RECIRCULATION RATE DEPENDS ON THE INCOMING WATER TURBIDITY. VARIABLE SPEED IS PROIVDED FOR RECIRCULATING DRIVE FOR THIS PURPOSE. • CHEMICALS ARE ADDED INTO THE LOWER PORTION OF REACTION ZONE OF THE CLARIFIER. THESE CAN ALSO BE ADDED IN TO THE INCOMING RAW WATER FEED PIPE. 47
  48. 48. RAW WATER TREATMENT CLARIFYING SYSTEM: SOILDS RECIRCULATION CLARIFIERS • FLOC GETS FULLY DENSIFIED WHEN WATER LEAVES AT BOTTOM, SETTLING RAPIDALLY AS CLEAR WATER RISES. • DUE TO THIS EFFECT USE OF HIGHER RISE RATES BECOMES POSSIBLE THAT REDUCES THE SIZE OF THE CLARIFIER. 48
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  53. 53. TROUBLE SHOOTING CLARIFIER (S) 53
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  58. 58. RAW WATER TREATMENT FILTRATION 58
  59. 59. RAW WATER TREATMENT FILTRATION: • FILTRATION COMPLETES THE WORK BEGUN BY CLARIFIERS • FILTRATION IS BASICALLY A PROCESS OF PLACING A POROUS/PERVIOUS BARRIER ACROSS FLOWING WATER TO REMOVE MATTER HELD IN SUSPENSION. • IN ITS SIMPLEST FORM CAN BE SURFACE OF THE BARRIER LIKE IN STRAINER OR BY REMOVAL THROUGHOUT THE DEPTH OF MEDIUM. 59
  60. 60. RAW WATER TREATMENT FILTRATION: • SURFACE FILTRATION IS LIMITED IN ITS REMOVAL CAPACITY. FOR INDUSTRIAL USE MEDIUM DEPTH IS THE ONLY PRACTICAL SOLUTION. • GRANULAR MEDIA ARE STANDARD FOR THIS PURPOSE. • IT FEATURES A BED OF GRADED FINE MEDIA SUPPROTED BY GRAVEL OF DIFFERENT GRADINGS THAT PREVENTS THE PERCOLATION OF FINE FILTERING MEDIA INTO THE COLLECTION SYSTEM. 60
  61. 61. RAW WATER TREATMENT FILTRATION: • OVERLYING WATER PERCOLATES THROUGH DOWN THROUGH THE MEDIA & IS COLLECTED AND REMOVED BY THE UNDERDRAIN SYTEM. • VARIOUS MECHANISMS WORK DURING FILTRATION LIKE SIMPLE ADSORPTION, ELECTROSTATIC EFFECTS, CHEMICAL BRIDGING, OR A COMBINATION. • THE PHYSICAL CHRACTERISTICS OF THE MEDIUM, FLOW RATE, PARTICLE SIZE, DENSITY, WATER TEMPERATURE AFFECT THE FILTER PERFORMANCE. 61
  62. 62. WATER BEING FILTERED FLOC BACTERIUM 0.001 mm STRAINING INTERCEPTION 0.5mm FILTER PORE FLOCCULATION SEDIMENTATION FILTER MEDIA 62
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  64. 64. GRAIN SIZE CROSS SECTION THROUGH SINGLE MEDIA UNSTRATIFIED BED GRAIN SIZE CROSS SECTION THROUGH DUAL MEDIA STRATIFIED BED GRAIN SIZE CROSS SECTION THROUGH SINGLE MEDIA STRATIFIED BED GRAIN SIZE CROSS SECTION THROUGH TRI MEDIA STRATIFIED BED 64
  65. 65. RAW WATER TREATMENT MEDIA PROPERTIES & SIZE: • NATURAL SILICA SAND SP. GR.- 2.65. • CRUSHED ANTHRACOAL SP. GR. 1.6 – 1.75 • ACTIVATED CARBON SP. GR. 0.4 – 0.7 • CRUSHED GARNET SP. GR. 4.1 TO 4.6 • MEDIA ARE SPECIFIED BY THE EFFECTAIVE SIZE AND UNIFORMITY COEFFICIENT. • COMMERCIAL SCREENING IS UNIFORMITY COEFFICIENT 1.6 TO 1.7. 65
  66. 66. GRAIN SIZE EFFECTIVE SIZE – d10 FOR WHICH 10% SAMPLE IS FINER UNIFORMITY COEFFICIENT – THE RATIO OF d60 FOR WHICH 60% SAMPLE IS FINER TO THE d10 66
  67. 67. RAW WATER TREATMENT BED DEPTH COMBINATIONS: • 0.4-0.6 mm SAND 250-300 mm • 1.0-1.2 mm SAND 600-900 mm • 0.8-1.0 mm ANTHRACITE 300-600 mm • 1.4-1.6 mm SAND/ANTHRACITE 750-900 mm • 1.6-1.8 mm SAND/ANTHRACITE 900-1100 mm • 2.0-4.0 mm SAND/ANTHRACITE 1250-1500 mm 67
  68. 68. RAW WATER TREATMENT PRESSURE FILTERS 68
  69. 69. RAW WATER TREATMENT FEATURES •VERTICAL CYLINDERICAL VESSEL INSIDE SUITABLY PROTECTED. •BOTTOM MEDIA SUPPORT AND COLLECTION /DISTRIBUTION SYSTEM. •INLET OUTLET CONNECTIONS. •FRONTAL PIPEWORK WITH ARRANGED NEST OF VALVES. •INSTRUMENTATION. BED PLATE STRAINER VERTCAL PRESSURE MEDIA FILTER 69
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  73. 73. RAW WATER TREATMENT GRAVITY FILTERS 73
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  75. 75. RAW WATER TREATMENT GENERAL FILTER OPERATION SERVICE RUN GRAVITY FILTERS. • DECLINING FLOW RATE. • CONSTANT FLOW RATE. 75
  76. 76. RAW WATER TREATMENT GENERAL FILTER OPERATION BACKWASH. • DRAIN. • AIR SCOUR. • SETTLE • BACKWASH WITH FILTERED WATER • RINSE 76
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  78. 78. RAW WATER TREATMENT GENERAL FILTER OPERATION PROBLEMS: EFFELUENT QUALITY. • PARTICLE SIZE LESS THAN 10-20 MICRON NEED SOME MEANS OF FLOCCULATION. • ACTIVATED SLUDGE PROCESS AND TRICKLING FILTERS HAVE 10-40% BY WEIGHT PARTICLE SIZE < 20 MICRON. IN THIS SIZE RANGE 60-90% REMOVAL IS OBTAINED. 78
  79. 79. RAW WATER TREATMENT GENERAL FILTER OPERATION PROBLEMS: SHORTER FILTER RUNS. • INCREASE FILTRATION RATE • CHANGE MEDIA GRAIN SIZE. FOR BIOLGICAL WASTE WATERS MEDIA GRAIN EFFECTIVE SIZE UP TO 2.5 mm CAN PROVIDE SATISFACTORY REMOVAL. RUN LENGTH CAN INCREASE 2 TO 3 TIMES THAN THAT WITH CONVENTIONAL 1.0 -2.0 mm. HOWEVER NEEDS CAREFUL STUDIES. • INCREASE ALLOWABLE HEAD LOSS 79
  80. 80. RAW WATER TREATMENT GENERAL FILTER OPERATION PROBLEMS: INEFFECTIVE MEDIA CLEANING & MUDBALL FORMATION. • INSUFFICIENT BACKWASH FLOWS. • PROGRESSIVELY MEDIA MAY GET COATED DUE TO INSUFFICIENT CLEANING OR PRESENCE OF GREASE ETC. IN WASTE WATERS. THIS GROWTH ON MEDIA GRAINS LEADS TO MUDBALLING. CHLORINATION AND PROPER BACKWASH REGIME SHOULD BE FOLLOWED. 80
  81. 81. RAW WATER TREATMENT GENERAL FILTER OPERATION PROBLEMS: PLUGGED MEDIA SUPPORT SYSTEMS. • KEEP BACK WASH STORAGE WATER CLEAN. • SELECT SUFFICIENT OPENING SIZE. • ENSURE PROPER DISINFECTION OF INFLUENT AND BACKWASH WATER. • AVOID SURGE OF WATER OR AIR INTO THE BACK WASH FLOWS. 81
  82. 82. RAW WATER TREATMENT GENERAL FILTER OPERATION PROBLEMS: MEDIA LOSS. • KEEP OPTIMUM BACK WASH FLOW RATE. • KEEP MEDIA FREE FROM BIO FOULING SINCE ANY GROWTH AROUND GRAINS CAN REDUCE THEIR NET DENISTY. • AVOID SURGE OF WATER OR AIR INTO THE BACK WASH FLOWS. 82
  83. 83. RAW WATER TREATMENT SLUDGE HANDLING 83
  84. 84. RAW WATER TREATMENT SLUDGE HANDLING/TREATMENT: TYPICALLY COMPRISE. • SLUDGE REMOVAL, COLLECTION & STORAGE. • SLUDGE THICKENING. • SLUDGE CONDITIONING. • SLUDGE DEWATERING/DRYING RENDERING FOR TRANSPORTATION. 84
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  90. 90. PLANT DATA KURIMAT POWER STATION 90
  91. 91. PLANT OVERVIEW: 91

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