FilmTec Technical Manual - Chester Paul Company

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The goal of a good design is to balance the flow rate of elements in the different positions. This can be achieved by thefollowing means:• Boosting the feed pressure between stages: preferred for efficient energy use• Apply a permeate backpressure only to the first stage of a two-stage system: low system cost alternative• Hybrid system: use membranes with lower water permeability in the first positions and membranes with higher waterpermeabilities in the last positions: e.g. high rejection seawater membranes in the first and high productivity seawatermembranes in the second stage of a seawater RO systemThe need for flow balancing and the method can also be determined after the system has been analyzed with ROSA.Step 10: Analyze and optimize the membrane systemThe chosen system should then be analyzed and refined using the Reverse Osmosis System Analysis (ROSA) computerprogram.Example• Feed source: brackish surface supply water, SDI < 5• Required permeate flow = 132 gpm (720 m 3 /d)• Six-element pressure vessels to be used1. Brackish surface supply water with SDI < 5; total permeate flow = 132 gpm (720 m 3 /d)2. Select plug flow3. BW30-365 (BW element with active membrane area of 365 ft 2 (33.9 m 2 ))4. Recommended average flux for surface supply water feed with SDI
3.11 System Performance Projection3.11.1 System Operating CharacteristicsBefore a system performance projection is run, one should be familiar with the operating characteristics of a system. Thesewill be explained using a typical example. Figure 3.10 shows a two-stage system with three six-element pressure vesselsusing a staging ratio of 2:1.Figure 3.10 Typical two-stage configuration for spiral-wound RO/NF elementsPermeateFeedIA 1 IA 2 … IA 6II 1 II 2 … II 6IB 1 IB 2 … IB 6ConcentrateTwo-stage systems are generally capable of operating at an overall recovery rate of 55 to 75%. For such systems theaverage individual recovery rate per element will vary from 7 to 12%. To operate a two-stage system at an overall recoverymuch higher than 75% will cause an individual element to exceed the maximum recovery limits shown in Section 3.9,Membrane System Design Guidelines. When this happens, a third stage will have to be employed which places 18 elementsin series, shifting the average element recovery rate to lower values.If two-stage systems are operated at too low a recovery (e.g. < 55%), the feed flow rates to the first-stage vessels can be toohigh, causing excessive feed/concentrate-side pressure drops and potentially damaging the elements. For example, aparticular FILMTEC 8-inch element may have a maximum feed flow rate in the range of 50–70 gpm (11–16 m 3 /h)depending on the water source. More information is available in Section 3.9, Membrane System Design Guidelines.As a result, systems with lower than 50% recovery will typically use single-stage configurations. Maximum flow considerationscan also limit the staging ratio. It is unlikely to find systems with staging ratios greater than 3:1. When a single RO element isrun, the operating variables are readily measured, and performance can be easily correlated. When a large number ofelements are combined in a system with a multiple staging (i.e. combination of elements in parallel and in series) configurationand only inlet operating variables are known, system performance prediction becomes considerably more complex. Feedpressures and salt concentrations for each element in series are changing. The rate and extent of these changes aredependent not only on the inlet conditions and overall recovery, but also on the stage configuration, i.e., staging ratio(s).Figure 3.11 illustrates the dynamic nature of predicting system performance based on the sum of individual elementperformances within the system. It shows how five different element performance parameters vary throughout the twelveseries positions in a 2:1 array of six-element pressure vessels. The system is operating at 75% recovery and 25°C with afeed osmotic pressure of 20 psi (1.4 bar, which roughly corresponds to a 2,000 mg/L feed TDS). The inlet feed pressure hasbeen adjusted so that the lead BW element is producing 7,500 gpd (28.4 m 3 /d), the maximum recommended permeate flowfor this particular element used on a well water system with feed SDI < 3.The top third of Figure 3.11 shows individual element permeate flows decreasing uniformly throughout the series configurationfrom 7,500 gpd (28.4 m 3 /d) in the lead element of the first stage to approximately 3,300 gpd (12.5 m 3 /d) in the last element ofthe second stage. The average element permeate rate is 5,800 gpd (22 m 3 /d) or 77% of the maximum allowable limit.Page 87 of 180 ® Trademark of The Dow Chemical <strong>Company</strong> ("Dow") or an affiliated company of Dow Form No. 609-00071
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DowWater SolutionsFILMTEC Reverse O
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2.6 Biological Fouling Prevention .
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1. Basics of Reverse Osmosis and Na
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Nanofiltration (NF)Nanofiltration r
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How to Use Reverse Osmosis and Nano
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1.4 Membrane DescriptionThe FILMTEC
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Membrane systems are typically desi
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1.8 Element CharacteristicsFILMTEC
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2. Water Chemistry and Pretreatment
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SeawaterSeawater with TDS of 35,000
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Table 2.5 Water analysis for RO/NFS
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Table 2.7 Solubility products of sp
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In this process, only Ca 2+ , Ba 2+
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For the concentration ranges presen
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The conditions for CaCO 3 scale con
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Figure 2.3 Langelier saturation ind
Page 35 and 36: These computations have been descri
Page 37 and 38: Figure 2.5 “K” versus ionic str
Page 39 and 40: Figure 2.6 Ksp for CaSO 4 versus io
Page 41 and 42: 2.4.6 Calcium Fluoride Scale Preven
Page 43 and 44: Figure 2.8 K sp for SrSO 4 versus i
Page 45 and 46: 2.4.7 Silica Scale PreventionDissol
Page 47 and 48: Table 2.10 Solubility of SiO 2 vers
Page 49 and 50: 2.4.8 Calcium Phosphate Scale Preve
Page 51 and 52: Table 2.9 Various fouling indicesIn
Page 53 and 54: Frequent shutdowns and start-ups sh
Page 55 and 56: If the differential pressure across
Page 57 and 58: 1. Intake (surface) or well, before
Page 59 and 60: or combined residual chlorine (CRC)
Page 61 and 62: 2.6.5 DBNPADBNPA (2,2, dibromo-3-ni
Page 63 and 64: 2.6.11 Use of Fouling Resistant Mem
Page 65 and 66: 2.11 Treatment of Feedwater Contain
Page 67 and 68: 2.13 Summary of Pretreatment Option
Page 69 and 70: 26. Handbook of Industrial Membrane
Page 71 and 72: Table 3.1 System design information
Page 73 and 74: 3.2 Batch vs. Continuous ProcessAn
Page 75 and 76: 3.4 Single-Stage SystemIn a single-
Page 77 and 78: The apparent salt passage of the sy
Page 79 and 80: Instead of having a separate high-p
Page 81 and 82: 3.9.1 Membrane System Design Guidel
Page 83 and 84: In Table 3.6, the small commercial
Page 85: Table 3.8 Number of stages of a sea
Page 89 and 90: 3.11.2 Design Equations and Paramet
Page 91 and 92: Table 3.10 Design equations for pro
Page 93 and 94: 3.11.3 Comparing Actual Performance
Page 95 and 96: The high-pressure concentrate is fe
Page 97 and 98: If the product water from an RO sys
Page 99 and 100: Besides the above recommendations,
Page 101 and 102: 4. Loading of Pressure VesselsThis
Page 103 and 104: The process of shimming is performe
Page 105 and 106: 4.5.2 Summary of Large Element Inte
Page 107 and 108: 5. System Operation5.1 Introduction
Page 109 and 110: 5.2.3 Start-Up SequenceProper start
Page 111 and 112: 5.2.4 Membrane Start-Up Performance
Page 113 and 114: 5.5.3 SeawaterIn principle, the ope
Page 115 and 116: Table 5.1 Reverse osmosis operating
Page 117 and 118: A. Normalized Permeate FlowQS=ΔPsP
Page 119 and 120: For the operating conditions we hav
Page 121 and 122: 4. During recirculation of cleaning
Page 123 and 124: 2. The cleaning pump should be size
Page 125 and 126: 6.7 Effect of pH on Foulant Removal
Page 127 and 128: Cleaning ProcedureThere are seven s
Page 129 and 130: If the organic fouling is the resul
Page 131 and 132: There are two factors that greatly
Page 133 and 134: 7. Handling, Preservation and Stora
Page 135 and 136: 7.4 Preservation of RO and NF Syste
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If the normalized actual performanc
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8.3.3 Localization of High Solute P
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Figure 8.2 Permeate probing apparat
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8.4.5 Performance TestThe standard
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8.5.1.1 Low Flow and Normal Solute
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. Metal Oxide FoulingMetal oxide fo
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. Organic FoulingThe adsorption of
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8.5.3 High Pressure DropHigh differ
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In case of fullfit or heat sanitiza
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Breakpoint chlorinationBreak tankBr
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FeedThe input solution to a treatme
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Milligram per litre (mg/L)Mixed-bed
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SBS Sodium bisulfite, NaHSO 3.Scale
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9.2 Specific Conductance of Sodium
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Figure 9.1 Conductivity of ionic so
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9.6 Temperature Correction FactorTa
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9.9 Osmotic Pressure of Sodium Chlo
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Details - TestEquipment andSpecific
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satisfactory for such a determinati
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case for almost all tested biocides
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9.12 Key Word IndexAbrasion - 150 B
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Positive displacement pump - 95 Shu
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FilmTec Technical Manual - Chester Paul Company

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