Mass Transfer And Hydraulic Testing Of The V-05 And V-10 Contactors With The Next Generation Solvent PDF Download

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Languages : en
Pages : 156

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Languages : en
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A solvent extraction system for removal of cesium (Cs) from alkaline solutions was developed utilizing a novel solvent invented at the Oak Ridge National Laboratory (ORNL). This solvent consists of a calix[4]arene-crown-6 extractant dissolved in an inert hydrocarbon matrix. A Modifier is added to the solvent to enhance the extraction power of the calixarene and to prevent the formation of a third phase. An additional additive, called a suppressor, is used to improve stripping performance. The process that deploys this solvent system is known as Caustic Side Solvent Extraction (CSSX). The solvent system has been deployed at the Savannah River Site (SRS) in the Modular CSSX Unit (MCU) since 2008. Subsequent development efforts by ORNL identified an improved solvent system that can raise the expected decontamination factor (DF) in MCU from H"00 to more than 40,000. The improved DF is attributed to an improved distribution ratio for cesium [D(Cs)] in extraction from H"5 to H"0, an increased solubility of the calixarene in the solvent from 0.007 M to>0.050 M, and use of boric acid (H3BO3) stripping that also yields improved D(Cs) values. Additionally, the changes incorporated into the Next Generation CSSX Solvent (NGS) are intended to reduce solvent entrainment by virtue of more favorable physical properties. The MCU and Salt Waste Processing Facility (SWPF) facilities are actively pursuing the changeover from the current CSSX solvent to the NGS solvent. To support this integration of the NGS into the MCU and SWPF facilities, the Savannah River Remediation (SRR)/ARP/MCU Life Extension Project requested that the Savannah River National Laboratory (SRNL) perform testing of the new solvent for the removal of Cs from the liquid salt waste stream. Additionally, SRNL was tasked with characterizing both strip (20-in long, 10 micron pore size) and extraction (40-in long, 20 micron pore size) coalescers. SRNL designed a pilot-scale experimental program to test the full size strip (V5) and extraction (V10) centrifugal contactors and the associated strip and extraction effluent coalescers to determine the hydraulic and mass transfer characteristics with the NGS. The test program evaluated the amount of organic carryover and the droplet size of the carryover phases using several analytical methods. Provisions were also made to enable an evaluation of coalescer performance. Stage efficiency and mass distribution ratios were determined using Cs mass transfer measurements. Using 20 millimolar (mM) extractant (instead of 50 mM), the nominal D(Cs) measured was 16.0-17.5. The data indicate that equilibrium is achieved rapidly and maintained throughout sampling. The data showed good stage efficiency for extraction (Tests 1A-1D), ranging from 98.2% for Test 1A to 90.5% for Test 1D. No statistically-significant differences were noted for operations at 12 gpm aqueous flow when compared with either 4 gpm or 8 gpm of aqueous flow. The stage efficiencies equal or exceed those previously measured using the baseline CSSX solvent system. The nominal target for scrub Cs distribution values are H".0-2.5. The first scrub test yielded an average scrub value of 1.21 and the second scrub test produced an average value of 0.78. Both values are considered acceptable. Stage efficiency was not calculated for the scrub tests. For stripping behavior, six tests were completed in a manner to represent the first strip stage. For three tests at the baseline flow ratios (O:A of 3.75:1) but at different total flow rates, the D(Cs) values were all similar at H".052. Similar behavior was observed for two tests performed at an O:A ratio of 7:1 instead of 3.75:1. The data for the baseline strip tests exhibited acceptable stage efficiency, ranging from 82.0% for low flow to 89-90% for medium and high flow. The difference in efficiency may be attributable to the low volume in the contactor housing at lower flow rates. The concentrations of Isopar L{reg_sign} and Modifier were measured using semi-volatile organic analysis (SVOA) and Fourier Transform Infrared (FTIR) Spectroscopy. However, due to issues associated with sample point configuration, the two methods cannot be correlated by this data. SVOA measurements provided a measure of Isopar L{reg_sign} and Modifier carryover for both stripping and extraction. For low-flow conditions in stripping, Isopar L{reg_sign} concentration measured H"00-500 mg/L. For moderate-flow conditions, Isopar L{reg_sign} was H"800-1900 mg/L. For high-flow conditions, Isopar L{reg_sign} was H"350-1750 mg/L for one test and H"00-800 mg/L for a second test. In extraction, the quantity of Isopar L{reg_sign} was H"60 mg/L at low flow, H"50-350 mg/L at moderate flow, and H"20-390 mg/L at high flow. For the above Isopar L{reg_sign} concentrations, Modifier was also present at the nominal Isopar-to-Modifier ratio of 3.65.

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Languages : en
Pages : 16

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The Modular Caustic Side Solvent Extraction (CSSX) Unit (MCU) facility at the Savannah River Site (SRS) is actively pursuing the transition from the current BOBCalixC6 based solvent to the Next Generation Solvent (NGS)-MCU solvent to increase the cesium decontamination factor. To support this integration of NGS into the MCU facility the Savannah River National Laboratory (SRNL) performed testing of a blend of the NGS (MaxCalix based solvent) with the current solvent (BOBCalixC6 based solvent) for the removal of cesium (Cs) from the liquid salt waste stream. This testing utilized a blend of BOBCalixC6 based solvent and the NGS with the new extractant, MaxCalix, as well as a new suppressor, tris(3,7dimethyloctyl) guanidine. Single stage tests were conducted using the full size V-05 and V-10 liquid-to-liquid centrifugal contactors installed at SRNL. These tests were designed to determine the mass transfer and hydraulic characteristics with the NGS solvent blended with the projected heel of the BOBCalixC6 based solvent that will exist in MCU at time of transition. The test program evaluated the amount of organic carryover and the droplet size of the organic carryover phases using several analytical methods. The results indicate that hydraulically, the NGS solvent performed hydraulically similar to the current solvent which was expected. For the organic carryover 93% of the solvent is predicted to be recovered from the stripping operation and 96% from the extraction operation. As for the mass transfer, the NGS solvent significantly improved the cesium DF by at least an order of magnitude when extrapolating the One-stage results to actual Seven-stage extraction operation with a stage efficiency of 95%.

Author: Donald S. Webster
Publisher:
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Category : Solvent wastes
Languages : en
Pages : 20

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Languages : en
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Annular centrifugal contactors (ACCs) are being evaluated for process-scale solvent extraction operations in support of Advanced Fuel Cycle Initiative (AFCI) separations goals. Process-scale annular centrifugal contactors have the potential for high stage efficiency if properly employed and optimized for the application. Hydraulic performance issues related to flow instability and classical flooding are likely unimportant, especially for units with high throughputs. However, annular mixing increases rapidly with increasing rotor diameter while maintaining a fixed g force at the rotor wall. In addition, for engineering/process-scale contactors, elevated rotor speeds and/or throughput rates, can lead to organic phase foaming at the rotor discharge collector area. Foam buildup in the upper rotor head area can aspirate additional vapor from the contactor housing resulting in a complete loss of separation equilibrium. Variable speed drives are thus desirable to optimize and balance the operating parameters to help ensure acceptable performance. Proper venting of larger contactors is required to balance pressures across individual stages and prevent vapor lock due to foam aspiration.

Author: Mohammad Younas
Publisher: John Wiley & Sons
ISBN: 3527348611
Category : Technology & Engineering
Languages : en
Pages : 372

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An eye-opening exploration of membrane contactors from a group of industry leaders In Membrane Contactor Technology: Water Treatment, Food Processing, Gas Separation, and Carbon Capture, an expert team of researchers delivers an up-to-date and insightful explanation of membrane contactor technology, including transport phenomena, design aspects, and diverse process applications. The book also includes explorations of membrane synthesis, process, and module design, as well as rarely discussed process modeling and simulation techniques. The authors discuss the technical and economic aspects of this increasingly important technology and examine the geometry, flow, energy and mass transport, and design aspects of membrane contactor modules. They also cover a wide range of application opportunities for this technology, from the materials sciences to process engineering. Membrane Contactor Technology also includes: A thorough introduction to the membrane contactor extraction process, including dispersion-free membrane extraction processes and supported liquid membrane processes Comprehensive explorations of membrane transport theory, including discussions of diffusional mass and heat transfer modeling, as well as numerical modeling In-depth examinations of module configuration and geometry, including design and flow configuration Practical discussions of modes or operation, including membrane distillation, osmotic evaporation, and forward osmosis Perfect for process engineers, biotechnologists, water chemists, and membrane scientists, Membrane Contactor Technology also belongs in the libraries of chemical engineers, polymer chemists, and chemists working in the environmental industry.

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Languages : en
Pages : 5

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The hydraulic performance of a 5-cm centrifugal contactor from Costner Industries Nevada Corporation (CINC) was measured for both one- and two-phase flow. Flow conditions and test liquids as well as the liquid height in the annular mixing zone and the occurrence of discontinuous (slug) flow in the interstage lines are reported. Results are compared with earlier results obtained using 2- and 4-cm contactors made at Argonne National Laboratory. In each case, one-phase flow tests can be used to predict behavior in two-phase flow. This makes the one-phase flow test a quality control tool for evaluating contactor rotors as they are manufactured. These results indicate that the 5-cm contactor works in the same way as the 2- and 4-cm contactors.

Author: Shailesh V. Potnis
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Category : Solar air conditioning
Languages : en
Pages : 216

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Languages : en
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Author: Robert H. Perry
Publisher: McGraw-Hill Professional Publishing
ISBN: 9780071355407
Category : Chemical engineering
Languages : en
Pages : 0

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Reference work for chemical and process engineers. Newest developments, advances, achievements and methods in various fields.