Troubleshooting Performance Issues of Reverse Osmosis Systems. Justyna Warczok TS&D

Transcription

1 Troubleshooting Performance Issues of Reverse Osmosis Systems Justyna Warczok TS&D

2 Troubleshooting means: identify & correct performance issues 1. Analyze the symptoms 2. Identify the causes 3. Take corrective measures 4. Take preventive measures

3 Troubleshooting Symptoms and causes a) Operational data b) Plant inspection c) Cleaning trial d) Further element testing: SOS Service

4 Troubleshooting Symptoms and causes a) Operational data b) Plant inspection c) Cleaning trial d) Further element testing: SOS Service

5 Early detection of performance issues Instruments, sensors Calibration of instruments Record keeping Data normalization: Translation of measured performance under prevailing conditions into performance under reference conditions

6 Symptoms of performance issues Loss of normalized permeate flow rate Increase in normalized salt passage Increase in pressure drop...are only recognized if they are significant

7 Symptoms of performance issues Loss of normalized permeate flow rate Sudden or gradual change? First or second stage? Cleaning experience?

8 Symptoms of performance issues Loss of normalized permeate flow rate Increase in normalized salt passage Sudden or gradual? First or second stage? Uniform or specific vessels? Probing!

9 Symptoms of performance issues Loss of normalized permeate flow rate Increase in normalized salt passage Increase in pressure drop First or second stage?

10 Symptoms Analysis Example CIP CIP 10

11 Symptoms Analysis Example CIP CIP 11

12 Performance issues - Indications Permeate Flow Symptoms observed Salt passage Pressure Drop Low High High Scaling, fouling Low Normal High Biofouling Direct cause Low Low Normal Organic fouling, compaction High High Normal Oxidative damage Normal High Normal Leaks, mechanical damage

13 Localize performance issue Colloidal and Biofouling Scaling Organic Fouling

14 Troubleshooting Symptoms and causes a) Operational data b) Plant inspection i. External Visual inspection Mapping, probing ii. Internal c) Cleaning trial d) Further element testing: SOS Service

15 Troubleshooting Symptoms and causes a) Operational data b) Plant inspection i. External Visual inspection Mapping, probing ii. Internal c) Cleaning trial d) Further element testing: SOS Service

16 Visual Inspection - Plant 16

17 Troubleshooting Symptoms and causes a) Operational data b) Plant inspection i. External Visual inspection Mapping, probing ii. Internal c) Cleaning trial d) Further element testing: SOS Service

18 Localize performance issue - Probing

19 Localize performance issue - Probing 19

20 Troubleshooting Symptoms and causes a) Operational data b) Plant inspection i. External Visual inspection Mapping, probing ii. Internal Visual inspection Element extraction: visual inspection, weighing, etc. c) Cleaning trial d) Further element testing: SOS Service

21 Visual Inspection - Inside PV Feed end Open the vessels on both ends 21

22 Troubleshooting Symptoms and causes a) Operational data b) Plant inspection i. External Visual inspection Mapping, probing ii. Internal Visual inspection Element extraction: visual inspection, weighing, etc. c) Cleaning trial d) Further element testing: SOS Service

23 Visual inspection - Element Quick observations: - Is the feed end discolored and/or have a musty odor? Is it red or orange? - On the downstream end is it gritty or white colored? Feed end Concentrate end

24 Visual inspection Open the vessels on both ends: Feed end Concentrate end

25 Shimming Feed end Shimming Shims 1/8ʺ to 1/4 ʺ freeboard 1. Push elements with appropriate tool 2. Shim so that the end connector cannot move when PV is closed

26 Start-up with air in system

27 Example: Visual observation? 27

28 Biofouling

29 Element Weighing

30 Extreme case of CaCO 3 scaling, concentrate side

31 Element Inspection Non-destructive tests: Visual inspection Weighing Vacuum leak test Standard performance test (Cleaning trial) No specific tools Requires specific tools Potential corrective measure

32 Troubleshooting Symptoms and causes a) Operational data b) Plant inspection c) Cleaning trial d) Further element testing: SOS Service

33 Cleaning 0.1% (w) NaOH, 35ºC, ph 12 or 1.0% (w) Na 4 EDTA, 35ºC, ph % (w) NaOH 35ºC, ph 12 or 0.025% (W) Na-DSS, 35ºC, ph % w) HCl, 25ºC, ph % (w) Na 2 S 2 O 4, 25ºC, ph 5 0.5% (w) H 3 PO 4, 25ºC, ph % (w) NH 2 SO 3 H, 25ºC, ph 3-4 Inorganic Salts (i.e. CaCO 3 ) Sulfate Scales (CaSO 4, BaSO 4 ) OK Metal Oxides (i.e. iron) Inorganic Colloids (silt) Preferred Silica Alternative Preferred Biofilms Alternative Preferred Preferred Alternative Alternative Preferred Alternative Alternative Organic Alternative Preferred

34 Cleaning Proper flow rates should be used Clean the stages of the RO or NF system separately: avoid pushing foulant from stage 1 into 2 nd proper flow rates in all stages Typically: combination of foulants and scalants FilmTec strongly recommends alkaline cleaning first. Acid cleaning first only if CaCO 3 or iron oxide/hydroxide.

35 Cleaning If the cleaning not effective, lower the feed flow rate increase contact time. If biofouling high ph (13): only lead element will see high ph: bio will consume the caustic. If its bio, find the source. SMBS tank open to atmosphere? ph needs to be monitored. SMBS can convert to sulfuric acid (permanent flow loss) Commercial cleaners check if perchlorate, perborate, metal content Never introduce air to the system - too many disadvantages.

36 Troubleshooting Symptoms and causes a) Operational data b) Plant inspection c) Cleaning trial d) Further element testing: SOS Service

37 Further tests - SOS 37

38 Further tests - SOS Microsoft Office Word Document 38

39 Membrane element evaluation Non-destructive tests: Visual inspection Weighing Vacuum leak test Standard performance test Cleaning trials Destructive tests: Autopsy and visual inspection of unrolled element (*) Pressure dying, autopsy and visual inspection Qualitative and quantitative analysis of foulants Membrane analysis for halogens Flat cell membrane testing cleaning trials

40 Membrane element evaluation - Example Non-destructive tests: Visual inspection - Feed

41 Membrane element evaluation - Example Non-destructive tests: Visual inspection - Concentrate

42 Membrane element evaluation - Example Non-destructive tests: Weighing: 15.8 kg Vacuum leak test: 70 mbar/min Standard performance test (BW30XFR-400/34i) Datasheet Product Flow (GPD) Rejection % Returned element standard test Product Flow (GPD) Rejection % (min) Delta P (PSI)

43 Autopsy results - Example 43

44 Drip test Acid drop test (HCl 2N) Positive CaCO 3 identification

45 Autopsy results - Example Species present in the fouling: Identification by WDXRF: S, Ca, P, Sr, Si, Al Identification by EDX: C, O, Si, S, Ca 45

46 Scaling Precipitation and deposition of sparingly soluble salts Ca 2+ CO 3 2- Starts in tail end of the system Caused by: Raw water changes (composition, ph, temperature) Improper dosage of scaling inhibitor Too high recovery F - PO 4 2- Sr 2+ SO 4 2- Ba 2+ Mg 2+ OH - SiO 2

47 Calcium carbonate scaling Correction:? Prevention:?

48 Calcium carbonate scaling Correction: Prevention: Acid cleaning; extended acid contact time Pretreatment improvement

49 Summary Symptoms observed Direct cause Problem source Correction Prevention Permeate Flow Salt passage Pressure Drop Scaling, fouling Poor pretreatment Clean or replace Improve pretreatement Normal Biofouling Nutrients, dead legs, poor operation Clean Improve pretreatment, system design, operation Normal Organic fouling Poor pretreatment Clean or replace e.g. Carbon filter Normal Compaction High temperature Replace Temperature control Normal Oxidative damage Oxidizing agents Replace Dechlorination Normal Normal Leaks, mechanical damage Loading or operation procedure Repair or replace Training

50 Thank You