Thermal Desalination using MEMS and Salinity-Gradient Solar Pond Technology University of Texas at El Paso El Paso, Texas Cooperative Agreement No. 98-FC-81-0047 Desalination Research and Development Program Report No. 80 August 2002 U.S. Department of the Interior Bureau of Reclamation Technical Service Center Water Treatment Engineering and Research Group Form Approved REPORT DOCUMENTATION PAGE OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suit 1204, Arlington VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Report (0704-0188), Washington DC 20503. 1. AGENCY USE ONLY (Leave Blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED August 2002 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS Thermal Desalination using MEMS and Salinity-Gradient Solar Pond Technology Agreement No. 98-FC-81-0047 6. AUTHOR(S) Huanmin Lu, John C. Walton, and Herbert Hein 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER University of Texas at El Paso El Paso, Texas 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING Bureau of Reclamation AGENCY REPORT NUMBER Desalination Research and Denver Federal Center Development Program Report No. 80 PO Box 25007 Denver CO 80225-0007 11. SUPPLEMENTARY NOTES 12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE Available from the National Technical Information Service, Operations Division, 5285 Port Royal Road, Springfield, Virginia 22161 13. ABSTRACT (Maximum 200 words) MEMS (multi-effect, multi-stage) flash desalination (distillation) driven by thermal energy derived from a salinity-gradient solar pond is investigated in this study for the purpose of improving the thermodynamic efficiency and economics of this technology. Three major tasks are performed: (1) a MEMS unit is tested under various operating conditions at the El Paso Solar Pond site; (2) the operation and maintenance procedures of the salinity-gradient solar pond coupled with the MEMS operation is studied; and (3) previous test data on a 24-stage, falling-film flash distillation unit (known as the Spinflash) is analyzed and compared with the performance of the MEMS unit. The data and information obtained from this investigation is applicable to a variety of thermal desalination processes using other solar options and/or waste heat. 14. SUBJECT TERMS-- 15. NUMBER OF PAGES thermal desalination, distillation, solar pond, brine concentration, MEMS, waste heat 45 16. PRICE CODE 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT OF REPORT OF THIS PAGE OF ABSTRACT UL UL UL UL NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89) Prescribed by ANSI Std. 239-18 298-102 Thermal Desalination using MEMS and Salinity-Gradient Solar Pond Technology Huanmin Lu, John C. Walton, and Herbert Hein University of Texas at El Paso El Paso, Texas Cooperative Agreement No. 98-FC-81-0047 Desalination Research and Development Program Report No. 80 August 2002 U.S. Department of the Interior Bureau of Reclamation Technical Service Center Water Treatment Engineering and Research Group iii Mission Statements U.S. Department of the Interior The mission of the Department of the Interior is to protect and provide access to our Nation’s natural and cultural heritage and honor our trust responsibilities to tribes. Bureau of Reclamation The mission of the Bureau of Reclamation is to manage, develop, and protect water and related resources in an environmentally and economically sound manner in the interest of the American public. Federal Disclaimer The information contained in this report regarding commercial products of firms may not be used for advertising or promotional purposes and is not to be construed as an endorsement of any product or firm by the Bureau of Reclamation. The information contained in this report was developed for the Bureau of Reclamation: no warranty as to the accuracy, usefulness, or completeness is expressed or implied. iv TABLE OF CONTENTS 1.0 Executive Summary................................................................................................................. 1 2.0 Background and Introduction to the Project............................................................................ 1 3.0 Conclusions and Recommendations ........................................................................................ 4 3.1 Conclusions..................................................................................................................... 4 3.2 Recommendations........................................................................................................... 5 4.0 Description of Test Facilities................................................................................................... 5 4.1 Salinity Gradient Solar Pond .......................................................................................... 5 4.2 MEMS Unit..................................................................................................................... 9 4.2.1 Equipment Description........................................................................................... 9 4.2.2 Process Description............................................................................................... 17 5.0 Work Performed..................................................................................................................... 18 5.1 Set Up and Refurbishment of the MEMS System ........................................................ 18 5.2 Performance Testing..................................................................................................... 18 5.3 Data Collection............................................................................................................. 19 5.4 Data Analysis................................................................................................................ 20 5.5 Comparison with Previous Tests with Spinflash Unit.................................................. 21 5.6 Solar Pond Operation and Maintenance ....................................................................... 21 6.0 Results and Analysis.............................................................................................................. 22 6.1 Operating Characteristics.............................................................................................. 22 6.2 Distillate Production Rate............................................................................................. 24 6.3 Energy Consumption Rate and Performance Ratio ...................................................... 29 6.4 Quality of Distillate Product......................................................................................... 34 6.5 Scaling and Corrosion................................................................................................... 35 6.6 Cooling with Pond Surface Water ................................................................................ 36 6.7 Comparison with Spinflash Unit................................................................................... 36 6.7.1 Spinflash Unit and Process Description................................................................ 36 6.7.2 Comparison with the MEMS Unit ........................................................................ 37 6.8 Economic Analysis....................................................................................................... 38 7.0 References.............................................................................................................................. 40 Appendix A — Summary of Test Data Appendix B — Daily Test Results i FIGURES Figure 1. Schematic of Zero Discharge Desalination System. ...................................................... 2 Figure 2. Picture of the El Paso Solar Pond................................................................................... 6 Figure 3. Specific Gravity Profile of the Solar Pond..................................................................... 7 Figure 4. Temperature Profile of the Solar Pond........................................................................... 7 Figure 5. Temperature Development of the El Paso Solar Pond. .................................................. 8 Figure 6. Picture of the MEMS Unit............................................................................................ 10 Figure 7. Schematic of the MEMS Unit and Piping System ....................................................... 11 Figure 8. General Configuration of a Flash Chamber ................................................................. 13 Figure 9. First Stage Condenser Configuration ........................................................................... 14 Figure 10. Second Stage Condenser Configuration..................................................................... 14 Figure 11. Third and Fourth Stage Condenser Configuration ....................................................