15 Matching Results

Search Results

Advanced search parameters have been applied.

Prediction of thermal front breakthrough due to fluid reinjection in geothermal reservoirs

Description: Chemically reactive tracers can be used to measure reservoir temperature distributions because of their extreme sensitivity to temperature. If a reactive tracer flows through a reservoir from an injection well to a production well, then early in the production history the tracer will contact mostly high temperatures and experience a high percentage of decomposition. As more energy is extracted from the reservoir, subsequent reactive tracer tests will show less decomposition. Tracers must be chosen which have reaction kinetics appropriate to the temperature patterns expected in the reservoir under consideration. If kinetics are too slow, no significant reaction occurs. If kinetics are too fast, essentially all of the tracer will react. In neither case can useful information be obtained. Seventeen chemically reactive tracers have been identified which are appropriate for geothermal reservoirs in the 70 to 275/sup 0/C range. Of the 17 tracer reactions investigated, 5 are hydrolysis of esters, 3 are hydrolysis of amines, and 9 are hydrolysis of aryl halides. A method for choice of the appropriate reactive tracer for a given reservoir is also presented. The method requires measurement of the residence time distribution (from a conservative tracer test), an estimate of reservoir temperature, and some simple geochemistry measurements and calculations. Several examples of choosing reactive tracers for existing geothermal reservoirs are given.
Date: January 1, 1987
Creator: Birdsell, S.A. & Robinson, B.A.
Partner: UNT Libraries Government Documents Department

Tracking thermal fronts with temperature-sensitive, chemically reactive tracers

Description: Los Alamos is developing tracer techniques using reactive chemicals to track thermal fronts in fractured geothermal reservoirs. If a nonadsorbing tracer flowing from the injection to production well chemically reacts, its reaction rate will be a strong function of temperature. Thus the extent of chemical reaction will be greatest early in the lifetime of the system, and less as the thermal front progresses from the injection to production well. Early laboratory experiments identified tracers with chemical kinetics suitable for reservoirs in the temperature range of 75 to 100/sup 0/C. Recent kinetics studies have focused on the kinetics of hydrolysis of derivatives of bromobenzene. This class of reactions can be used in reservoirs ranging in temperature from 150 to 275/sup 0/C, which is of greater interest to the geothermal industry. Future studies will include laboratory adsorption experiments to identify possibly unwanted adsorption on granite, development of sensitive analytical techniques, and a field demonstration of the reactive tracer concept.
Date: January 1, 1987
Creator: Robinson, B.A. & Birdsell, S.A.
Partner: UNT Libraries Government Documents Department

Hot Dry Rock geothermal reservoir model development at Los Alamos

Description: Discrete fracture and continuum models are being developed to simulate Hot Dry Rock (HDR) geothermal reservoirs. The discrete fracture model is a two-dimensional steady state simulator of fluid flow and tracer transport in a fracture network which is generated from assumed statistical properties of the fractures. The model's strength lies in its ability to compute the steady state pressure drop and tracer response in a realistic network of interconnected fractures. The continuum approach models fracture behavior by treating permeability and porosity as functions of temperature and effective stress. With this model it is practical to model transient behavior as well as the coupled processes of fluid flow, heat transfer, and stress effects in a three-dimensional system. The model capabilities being developed will also have applications in conventional geothermal systems undergoing reinjection and in fractured geothermal reservoirs in general. 15 refs., 7 figs.
Date: January 1, 1989
Creator: Robinson, B.A. & Birdsell, S.A.
Partner: UNT Libraries Government Documents Department

Modeling and data analysis of a palladium membrane reactor for tritiated impurities cleanup

Description: A Palladium Membrane Reactor (PMR) is under consideration for the tritium plant for the International Thermonuclear Experimental Reactor (ITER). The ITER reactor exhaust will contain tritiated impurities such as water and methane. Tritium will need to be recovered from these impurities for environmental and economic reasons. For this purpose a promising device, PMR, has been proposed. The PMR is a combined permeator and catalytic reactor. Shift catalysts are used to foster reactions such as water-gas shift, H{sub 2}O + CO {yields} H{sub 2} + CO{sub 2}, and methane steam reforming, CH{sub 4} + H{sub 2}O {yields} 3H{sub 2} + CO. Due to thermodynamic limitations these reactions only proceed to partial completion. Thus, a Pd/Ag membrane, which is exclusively permeable to hydrogen isotopes, is incorporated into the reactor. By maintaining a vacuum on the permeate, product hydrogen isotopes are removed, enabling the reactions to proceed to completion. A model has been developed to study the complex interactions in a PMR so that the optimal design can be determined. The model accounts for the coupled effects of transport-limited permeation of hydrogen isotopes and chemical reactions. The permeation model is an extension of previous models that include the effects of temperature, wall thickness, reaction-side pressure, and permeate-side pressure. Reaction rates for methane steam reforming and the water-gas shift reaction are incorporated into the model along with the respective reverse reactions. The model is compared to PMR data and used to investigate the concentration and pressure profiles in the reactor. Due to the interactions of permeation and reaction complex profiles can be produced in a PMR. For example, the water concentration often increases after the inlet to the PMR to a maximum value, and then decreases to the low values expected with a PMR. Detailed information like this is required for the design and ...
Date: July 1, 1995
Creator: Birdsell, S.A. & Willms, R.S.
Partner: UNT Libraries Government Documents Department

Hot dry rock fracture propagation and reservoir characterization

Description: North America's largest hydraulic fracturing opeations have been conducted at Fenton hill, New mexico to creae hot dry rock geothermal reservoirs. Microearthquakes induced by these fracturing operations were measured with geophones. The large volume of rock over which the microearthquakes were distributed indicates a mechanism of hydraulic stimulation which is at odds with conventional fracturing theory, which predicts failure along a plane which is perpendicular to the least compressive earth stress. Shear slippage along pre-existing joints in the rock is more easily induced than conventional tensile failure, particularly when the difference between minimum and maximum earth stresses is large and the pre-existing joints are oriented at angles between 30 and 60)degree) to the principal earth stresses, and a low viscosity fluid like water is injected. Shear slippage results in local redistribution of stresses, which allows a branching, or dendritic, stimulation pattern to evolve, in agreement with the patterns of microearthquake locations. Field testing of HDR reservoirs at the Fenton Hill site shows that significant reservoir growth occurred as energy was extracted. Tracer, microseismic, and geochemical measurements provided the primary quantitative evidence for the increases in accessible reservoir volume and fractured rock surface area. These temporal increases indicate that augmentation of reservoir heat production capacity in hot dry rock system occurred. For future reservoir testing, Los Alamos is developing tracer techniques using reactive chemicals to track thermal fronts. Recent studies have focused on the kinetics of hydrolysis of derivatives of bromobenzene, which can be used in reservoirs as hot as 275)degree)C.
Date: January 1, 1988
Creator: Murphy, H.; Fehler, M.; Robinson, B.; Tester, J.; Potter, R. & Birdsell, S.
Partner: UNT Libraries Government Documents Department

Tritium recovery from tritiated water with a two-stage palladium membrane reactor

Description: A process to recover tritium from tritiated water has been successfully demonstrated at TSTA. The 2-stage palladium membrane reactor (PMR) is capable of recovering tritium from water without generating additional waste. This device can be used to recover tritium from the substantial amount of tritiated water that is expected to be generated in the International Thermonuclear Experimental Reactor both from torus exhaust and auxiliary operations. A large quantity of tritiated waste water exists world wide because the predominant method of cleaning up tritiated streams is to oxidize tritium to tritiated water. The latter can be collected with high efficiency for subsequent disposal. The PMR is a combined catalytic reactor/permeator. Cold (non-tritium) water processing experiments were run in preparation for the tritiated water processing tests. Tritium was recovered from a container of molecular sieve loaded with 2,050 g (2,550 std. L) of water and 4.5 g of tritium. During this experiment, 27% (694 std. L) of the water was processed resulting in recovery of 1.2 g of tritium. The maximum water processing rate for the PMR system used was determined to be 0.5 slpm. This correlates well with the maximum processing rate determined from the smaller PMR system on the cold test bench and has resulted in valuable scale-up and design information.
Date: April 1, 1997
Creator: Birdsell, S.A. & Willms, R.S.
Partner: UNT Libraries Government Documents Department

Ultra-high tritium decontamination of simulated fusion fuel exhaust using a 2-stage palladium membrane reactor

Description: A 2-stage cold (non-tritium) PMR system was tested with the ITER mix in61 days of continuous operation. No decrease in performance was observed over the duration of the test. Decontamination factor (DF) was found to increase with decreasing inlet rate. Decontamination factors in excess of 1.4 {times} 10{sup 5} were obtained, but the exact value of the highest DF could not be determined because of analysis limitations. Results of the 61-day test were used to design a 2-stage PMR system for use in tritium testing. The PMR system was scaled up by a factor of 6 and built into a glovebox in the Tritium Systems Test Assembly (TSTA) of the Los Alamos National Laboratory. This system is approximately 1/5th of the expected full ITER scale. The ITER mix was injected into the PMR system for 31 hours, during which 4.5 g of tritium were processed. The 1st stage had DF = 200 and the 2nd stage had DF = 2.9 {times} 10{sup 6}. The overall DF = 5.8 {times} 10{sup 8}, which is greater than ITER requirements.
Date: December 1996
Creator: Birdsell, S. A.; Willms, R. S. & Wilhelm, R. C.
Partner: UNT Libraries Government Documents Department

Recent palladium membrane reactor development at the tritium systems test assembly

Description: The palladium membrane reactor (PMR) is proving to be a simple and effective means for recovering hydrogen isotopes from fusion fuel impurities such as methane and water. This device directly combines two techniques which have long been utilized for hydrogen processing, namely catalytic shift reactions and palladium/silver permeators. A proof-of-principle (PMR) has been constructed and tested at the Tritium Systems Test Assembly of Los Alamos National Laboratory. The first tests with this device showed that is was effective for the proposed purpose. Initial work concluded that a nickel catalyst was an appropriate choice for use in a PMR. More detailed testing of the PMR with such a catalyst was performed and reported in other works. It was shown that a nickel catalyst-packed PMR did, indeed, recover hydrogen from water and methane with efficiencies approaching 100% in a single processing pass. These experiments were conducted over an extended period of time and no failure or need for regeneration was encountered. These positive results have prompted further PMR development. Topics addressed include alternate PMR geometries and initial testing of the PMR with tritium. These are the subjects of this paper.
Date: July 1, 1995
Creator: Willms, R.S.; Birdsell, S.A. & Wilhelm, R.C.
Partner: UNT Libraries Government Documents Department

Calculation of Savannah River K Reactor Mark-22 assembly LOCA/ECS power limits

Description: This paper summarizes the results of TRAC-PF1/MOD3 calculations of Mark-22 fuel assembly of loss-of-coolant accident/emergency cooling system (LOCA/ECS) power limits for the Savannah River Site (SRS) K Reactor. This effort was part of a larger effort undertaken by the Los Alamos National Laboratory for the US Department of Energy to perform confirmatory power limits calculations for the SRS K Reactor. A method using a detailed three-dimensional (3D) TRAC model of the Mark-22 fuel assembly was developed to compute LOCA/ECS power limits. Assembly power was limited to ensure that no point on the fuel assembly walls would exceed the local saturation temperature. The detailed TRAC model for the Mark-22 assembly consisted of three concentric 3D vessel components which simulated the two targets, two fuel tubes, and three main flow channels of the fuel assembly. The model included 100% eccentricity between the assembly annuli and a 20% power tilt. Eccentricity in the radial alignment of the assembly annuli arises because axial spacer ribs that run the length of the fuel and targets are used. Wall-shear, interfacial-shear, and wall heat-transfer correlations were developed and implemented in TRAC-PF1/MOD3 specifically for modeling flow and heat transfer in the narrow ribbed annuli encountered in the Mark-22 fuel assembly design. We established the validity of these new constitutive models using separate-effects benchmarks. TRAC system calculations of K Reactor indicated that the limiting ECS-phase accident is a double-ended guillonite break in a process water line at the pump discharge (i.e., a PDLOCA). The fuel assembly with the minimum cooling potential is identified from this system calculation. Detailed assembly calculations then were performed using appropriate boundary conditions obtained from this limiting system LOCA. Coolant flow rates and pressure boundary conditions were obtained from this system calculation and applied to the detailed assembly model.
Date: January 1, 1992
Creator: Fischer, S.R.; Farman, R.F. & Birdsell, S.A.
Partner: UNT Libraries Government Documents Department

Advancing the technology base for high-temperature membranes

Description: This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This project addresses the major issues confronting the implementation of high-temperature membranes for separations and catalysis. We are pursuing high-temperature membrane systems that can have a large impact for DOE and be industrially relevant. A major obstacle for increased use of membranes is that most applications require the membrane material to withstand temperatures above those acceptable for polymer-based systems. Advances made by this project have helped industry and DOE move toward high-temperature membrane applications to improve overall energy efficiency.
Date: October 1, 1997
Creator: Dye, R.C.; Birdsell, S.A. & Snow, R.C.
Partner: UNT Libraries Government Documents Department

Effect of inlet conditions on the performance of a palladium membrane reactor

Description: Palladium membrane reactors (PMR) will be used to remove tritium and other hydrogen isotopes from impurities, such as tritiated methane and tritiated water, in the exhaust of the International Thermonuclear Experimental Reactor. In addition to fusion-fuel processing, the PMR system can be used to recover tritium from tritiated waste water. This paper investigates the effect of inlet conditions on the performance of a PMR. A set of experiments were run to determine, independently, the effect of inlet compositions and residence time on performance. Also, the experiments were designed to determine if the injected form of hydrogen (CH{sub 4} or H{sub 2}O) effects performance. Results show that the PMR operates at optimal hydrogen recovery with a broad range of inlet compositions and performance is shown to increase with increased residence time. PMR performance is shown to be independent of whether hydrogen is injected in the form of CH{sub 4} or H{sub 2}O.
Date: October 1, 1997
Creator: Birdsell, S.A.; Willms, R.S.; Arzu, P. & Costello, A.
Partner: UNT Libraries Government Documents Department

Comparison of methods for separating small quantities of hydrogen isotopes from an inert gas

Description: It is frequent within tritium processing systems that a small amount of hydrogen isotopes (Q{sub 2}) must be separated from an inert gas such as He, Ar and N{sub 2}. Thus, a study of presently available technologies for effecting such a separation was performed. A base case and seven technology alternatives were identified and a simple design of each was prepared. These technologies included oxidation-adsorption-metal bed reduction, oxidation-adsorption-palladium membrane reactor, cryogenic adsorption, cryogenic trapping, cryogenic distillation, hollow fiber membranes, gettering and permeators. It was found that all but the last two methods were unattractive for recovering Q{sub 2} from N{sub 2}. Reasons for technology rejection included (1) the method unnecessarily turns the hydrogen isotopes into water, resulting in a cumbersome and more hazardous operation, (2) the method would not work without further processing, and (3) while the method would work, it would only do so in an impractical way. On the other hand, getters and permeators were found to be attractive methods for this application. Both of these methods would perform the separation in a straightforward, essentially zero-waste, single step operation. The only drawback for permeators was that limited low-partial Q{sub 2} pressure data is available. The drawbacks for getters are their susceptibility to irreversible and exothermic reaction with common species such as oxygen and water, and the lack of long-term operation of such beds. More research is envisioned for both of these methods to mature these attractive technologies.
Date: March 1, 1998
Creator: Willms, R.S.; Tuggle, D.; Birdsell, S.; Parkinson, J.; Price, B. & Lohmeir, D.
Partner: UNT Libraries Government Documents Department

Geochemistry and tracer behavior during a thirty day flow test of the Fenton Hill HDR (Hot Dry Rock) reservoir

Description: During the most recent circulating flow test of the Fenton Hill Hot Dry Rock (HDR) geothermal reservoir, the geochemical behavior of the produced fluid was monitored continuously to determine the concentrations of dissolved anions and cations and dissolved gases. Chemistry results have aided in the development of reservoir models and in the determination of potential chemistry-related operation problems such as corrosion and gas handling in future energy extraction tests. Results of two radioactive tracer experiments suggest flow through a large, highly-fractured region of rock. This rock volume is equivalent to a sphere of diameter approximately equal to the separation distance between the injection and production points in the two wells.
Date: January 1, 1987
Creator: Robinson, B.A.; Aguilar, R.G.; Kanaori, Yuji; Trujillo, P.E. Jr.; Counce, D.A.; Birdsell, S.A. et al.
Partner: UNT Libraries Government Documents Department