Improved Robustness and Chemical Resistance of Nanofiltration Membranes GeoEnergy 2018

Transcription

1 Improved Robustness and Chemical Resistance of Nanofiltration Membranes GeoEnergy Z. Alam, M. Boczkowski, B. Chaudhari, P. Eriksson, SUEZ Water Technologies and Solutions, 2018: Advancement of Nanofiltration Membrane: Improved Robustness and Chemical Resistance

2 Agenda Historical performance issues Recent Improvement in membrane robustness and its relevance to EOR Higher ph tolerance Alkaline cleaning Biocide compatibility Conclusions

3 Historical data Umm-Lujj Desalination Plant Seawater RO plant commissioned in 1986 In 2000, one of the two trains converted to NF- SWRO Courtesy (Hassan et al. & A.A. Al-Hajouri et al. ) NF Feed Water Quality Parameter Value ph 6 (adjusted) Temperature C SDI 3.5 TDS 46,500 NF Plant Description Parameter Value Capacity, m 3 /hr 234 Recovery 65% # of NF module 162 Stage 1

4 % Rejection Historical data Umm-Lujj: Impact of Alkaline Clean 2000 to 2001 After 3 Alkaline Cleans Sulfate rejection decreased from >99% to 98.7% Hardness rejection decreased from 97% to 73% Courtesy Hasan et al Hardness & Sulfate Rejection after Alkaline Clean Total Hardness Calcium Magnesium Sulfate Initial After Clean 1 After Clean 3 Hardness rejection is an important consideration for drilling fluids, well completion fluids and ASP flooding

5 Positive impact of acid on membrane performance 6.1 ph 8.1 ph Impact of Feed Water ph: Historical Performance NF demonstration study by Saline Water Conversion Corporation - SWCC (Courtesy Abdullatef et al) Rejection of most the ions decreased when acid dosing was eliminated (Feed ph increased to 8.1 from 6.1)

6 Improved robustness: High ph Tolerance

7 Field trial at ph > Seawater natural ph is around 8 Earlier versions required ph adjustments to less than 7 incurring additional costs Newer generation of SWSR membranes can operate at seawater natural ph (>8) without any noticeable deterioration in sulfate rejection Feed Sulfate, mg/l as SO Feed Sulfate, ppm Permeate Sulfate, ppm Before CIP After CIP Oct-14 7-Dec Jan Feb-15 6-Apr May-15 NF membranes are commonly used in SRPs and low salinity injection systems (EOR) Permeate Sulfate, mg/l as SO 4 --

8 Improved robustness: Alkaline Clean

9 Accelerated Test Developed an accelerated testing protocol to examine the robustness of newer NF formulations Shorter duration Less resource intensive Validated the new protocol by comparing the results from the accelerated testing with pilot testing

10 Standard wet test and CIP conditions Membrane performance test with MgSO4 Feed solution: 2000 ~2200 ppm MgSO4 Feed ph: 6.86~7.00 Feed pressure: 110±1 psi Feed temperature: 25±1 deg.c Permeate recovery: 15~17 % Wet Test duration: 4 hrs.(initial test) 24 hrs. (after RO water compaction) 24 hrs. (after 10 CIP s) Water passing criteria: 98% Rej 1 2 Baseline & performance test with Seawater Feed solution: Seawater (NF pilot Seawater feed from Tuas site) Feed ph : Feed pressure: variable (depends on membrane flux) Feed temperature: 25±0.5 deg.c Membrane flux: 16~ 17 gfd Permeate recovery: 15±1% Test duration: 24hr Alkaline CIP conditions CIP solution: Alkaline cleaner Kleen MCT-511 Dosage wt.: 2.0 % CIP solution ph : ±0.5 CIP solution temperature (during CIP) : 35 ±1deg.C Feed pressure : 60±2psi Concentrate flow: 5 lpm CIP Duration (total) : 6 hrs. (2hr circulation + 2hr soaking + 2hr circulation) 3 4 Acidic CIP conditions CIP solution: Acidic cleaner Kleen MCT-882 Dosage wt. : 2.0 % CIP solution ph : 2.50±0.5 CIP solution temperature (during CIP) : 35±1 deg.c Feed pressure : 60±2 psi Concentrate flow: 5 lpm CIP Duration (total): 3 hrs. (1hr circulation + 1hr soaking + 1hr circulation) Alkaline CIP (6hrs) Acidic CIP(3hrs) -> Seawater wet test (24hrs) = 1 CIP cycle Repeated 12 times to established the membrane performance deterioration trend

11 Sulfate Rejecttion, % Hardness Rejecttion, % Accelerated test vs. field trial Sulfate Rejection: Accelerated Testing Vs Field Trial Hardness Rejection: Accelerated Testing Vs Field Trial , ,6 Field Trial 80 Field Trial 99,4 99,2 Accelerated Lab Test 70 Accelerated Lab Test Membranes behave differently in different seawaters, phs, biocides, temperatures and so on. Waters for EOR vary from one source to the next. Accelerated testing enables to optimize membrane selection without delaying the project and is an important risk mitigating step

12 Improved robustness: Biocide Compatibility

13 Non-Oxidizing Biocides are used to control Biocides can potentially affect the robustness of NF membrane Why Alternative Biocides Microorganism in pipelines, e.g., SRB Membrane fouling Biofilm formation Loss of rejection

14 Compatibility Test Soak Test: Prescreening at different biocide concentration at target temperature and ph Monitor permeability and rejection twice per day for 7-days Continuous Test: Continuous test at maximum compatible concentration for ~100,000 ppm-hrs Monitor pressure, flow, conductivity continuously Monitor sulfate rejection twice per day Monitor cleanability every 50,000 ppmhrs

15 A-Value Soak Test: THPS Based Biocide THPS Based Biocide A-Value Trend (Before & After Biocide Soaking) Impact on membrane robustness varies with manufacturer of the THPS based biocides No impact on MgSO4 rejection even at 10,000 ppm dose ppm-hr Baseline After 24-hrs Soaking After 244-hrs Soaking Small decrease in permeability with one of the THPS based biocides at very high concentration Longer term test with 1000 ppm dose

16 Permeability MgSO 4 Rejection (%) Continuous Test 25 Permeability & Rejection Trend with 100 & 1000 ppm of THPS based Biocide 120 No noticeable decrease in either permeability or rejection after 75,000 ppm-hrs of continuous test <8% decrease in permeability <2% decrease in MgSO4 rejection ph can decrease with THPS addition ppm - hr Permeability % Rejection A common and inexpensive biocide. However, not every manufacturer is equal and MSDS don t tell the whole story.

17 Continuous Test In a similar fashion to THPS based biocides, we tested Glutaraldehyde based biocides Even less variability in permeability and rejection was observed vs control than in the case of THPS A common and inexpensive biocide. However, not every manufacturer is equal and MSDS don t tell the whole story.

18 Conclusions Improved membrane performance for EOR and Water injection applications Higher ph tolerance Alkaline cleaning Biocide compatibility Validated testing method to evaluate membranes for new EOR applications with different water characteristics and biocides