Linear Alkyl benzene Sulfonic Acid (LAS) is the main ingredient of many commercial formulations for industrial and domestic synthetic detergents. The current industrial LAS production method includes sulfonation of linear alkylbenzene (LAB) with sulfur trioxide in tubular falling film reactors. In such reactors a diluted gaseous stream of SO3 and dry air, feed gas, is contacted with liquid LAB while both reactants flow co-currently downward. The reaction is highly exothermic and product quality is primarily dependent on heat removal efficiency from the reactors, and also contact time. This research project investigates a new route for the production of LAS. This new method employs SO2 oxidation over activated carbon at 25oC to SO3, followed by the extraction of the adsorbed SO3 from the activated carbon by supercritical carbon dioxide (SCCO2). The condensed phase CO2-SO3 mixture after expansion is contacted with LAB where sulfonation of this substrate occurs to yield LAS. The new route should offer lower operating temperatures and lower feed gas SO3 concentrations in the sulfonation reaction to minimize loss of LAB to side-reactions and reduce LAS contamination (that appears as unacceptable product discoloration). The laboratory set up was designed, assembled and in total 25 experiments were carried out. Over the course of experiments a number of remedial actions were taken to improve set up functionality and reaction yield. The problems needed to be tackled included feed gas moisture removal, SO2/SO3 adsorption/desorption efficiency, homogeneous mixing of reactants and reducing the SCCO2/SO3 flow rate through LAB columns. The maximum LAB/LAS conversion obtained was 3.6 % per sulfonation column. The maximum SO3 removal efficiency from activated carbon obtained was 77%. It was also found that nitrogen gas in a specific temperature range may be used as the desorbing agent in lieu of supercritical carbon dioxide with satisfactory performance. As supplementary data, the Brauner-Emmet-Teller surface area of activated carbon type BPL 6x16 from “Calgon Carbon Corporation” was measured.

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Taking into account the expected increase in global energy demands and increasing climate change issues, there is a pressing need to develop new environmentally sustainable energy systems. Nuclear energy will play a major role in being part of the energy mix since it offers a relatively clean, safe and reliable source of electrical energy. However, opportunities for building new generation nuclear systems will depend on their economic and safety attractiveness as well as their flexibility in design to adapt in different countries and situations. Keeping these objectives in mind, a framework for international cooperation was set forth in a charter of Generation IV International Forum (GIF) (GIF Charter, 2002) and six design concepts were selected for further development. To achieve high thermal efficiencies of up to 45 ??? 50%, the use of SuperCritical Fluids (SCFs) as working fluids in heat transfer cycles is proposed Generation IV designs. An important aspect towards development of SCF applications in novel Gen IV Nuclear Power Plant (NPP) designs is to understand the thermodynamic behavior and prediction of Heat Transfer Coefficients (HTCs) at supercritical (SC) conditions. In addition to the nuclear power industry applications; SCFs are also expected to play a vital role in a number of other important technologies such as refrigeration systems, and geothermal systems, to name a few. Given the potential for vast number of applications of SCFs in industry, the objective of this work was to gain an understanding on the behavior of SCFs and to develop a fundamental knowledge of the heat-transfer processes and correlations for SC Water and SC CO2 flowing in bare circular tubes. Experimental datasets for SC Water and SC CO2 were compiled and used to obtain a basic 1-D empirical correlation that can predict HTC in bare circular tubes during the transient phases. The accuracy of these correlations was also analyzed using statistical techniques. Limitations and applications for 1-D correlations are discussed as well. The new correlations showed promising results for HTC and Tw calculations for the reference dataset with uncertainty of about ??25% for HTC values and about ??10-15% for the calculated wall temperature.

There has been an ever-increasing demand for power generation, which is predicted to grow as society becomes more advanced. However, tradition fossil fuels are beginning to deplete, and there is a great necessity for alternative fuel sources that will bridge the gap between energy production and consumption. To decrease the high demand alternative fuel sources are gaining in popularity. The supercritical carbon dioxide Brayton power cycle has been proposed as a possible cycle for nuclear and concentrated solar power generation. Two main advantages of having supercritical carbon dioxide are the large property variations and component size associated with power cycle. Forced convection heat transfer of supercritical carbon dioxide in printed circuit heat exchanger geometries were investigated in the following study using a finite volume framework and the FLUENT 12.1 code. The geometries of interest were: non- chamfered zig-zag, chamfered zig-zag, and air foil. Flow through the three geometries was in the horizontal orientation and subject to a heating mode operation. A range of testing conditions were explored, including operating pressures between 7.5 to 10.2 MPa with the mass flux ranging from 326 to 762 kg/m2-s. Due to the turbulent nature of this problem, the k−E with enhanced wall treatment and shear stress transport k−ω turbulence models were considered. With this addition a total of 54 simulations were performed. Results indicated that there was an increase in the heat transfer coefficient as the supercritical carbon dioxide reached the pseudocritical temperature, conversely as there was an increase in operating pressure, the heat transfer coefficient decreased. Nevertheless, this increase near the pseudocritical temperature was due to a sharp increase in the specific heat. Mass flux effects indicated that there was an increase in heat transfer as the mass flux was increased. This was due to the increase in Reynolds number near the pseudocritical temperature. Next, pressure losses were investigated for the three geometries. The non-chamfered zig-zag channel had the greatest pressure loss associated with it, while the air foil channel had the least. Based on the results, the ratio of the friction factor to heat transfer for the non-chamfered and chamfered zig-zag geometries were approximately 2.65 and 1.57 times higher than for the air foil, thus leading to the idea that the air foil channel may be best suited for practical applications. Finally, the simulation results were compared to experimental data and existing correlations. Many existing correlations failed to accurately predict the magnitude of heat transfer, although they exhibited a similar trend. A new correlation was developed for the zig-zag geometries based on the numerical data obtained during this investigation and published experimental data. The new correlation is able to predict the maximum heat transfer coefficient within 12.4%.

Extraction of hydrocarbons from an Athabasca oil sand slurry were conducted using supercritical carbon dioxide (SC-CO2). The oil sand was slurried to a 1:1 ratio with water and experiments were conducted using a laboratory-scale batch supercritical fluid extraction (SFE) system. Preliminary tests revealed the importance of mixing rate on hydrocarbon yields. A 2^3 factorial experiment was then conducted to test the effect of temperature, pressure, and modifier (toluene) addition on hydrocarbon extraction yield. When toluene was absent, hydrocarbon extraction yields were greater at the high temperature (60°C); however, when toluene was present, the combination of low temperature (31°C) and high pressure (24.1MPa) provided greater extraction yields. The experiment that produced the highest cumulative hydrocarbon extraction yield was analyzed by GC-FID for product-quality. Two composite samples and one time series sample revealed a carbon distribution range of the extract centering on C25, corresponding to the light gas oil range as classified in petroleum fractions. / Environmental Science

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Noble gas partitioning between supercritical CO2-H2O phases can be used to monitor Carbon Capture and Storage (CCS) sites and their natural analogues. However, in order for viable application, noble gas partitioning within these environments must be well constrained. Present estimates of partition coefficient for these systems are taken from the low pressure pure noble gas-water experiments of Crovetto et al. and Smith (Crovetto et al., 1982; Smith, 1985). The effect a supercritical CO2 phase may have on noble gas partitioning is assumed negligible, although this has not been empirically verified. In this work this assumption of noble gas behaviour within a supercritical CO2-H2O binary phase system is evaluated using a combined approach of experiment and simulation. Using a specially commissioned high pressure system at the British Geological Survey paired CO2 and H2O samples were collected from noble gas-enriched systems at pressures and temperatures ranging between 90 – 140 bar and 323.15 – 373.15 K. These were analysed for their noble gas content using a quadrupole mass spectrometer system developed specifically for this project. By comparing the relative concentrations of noble gases in each phase partition coefficients were defined for the experimental conditions. These were compared to their low pressure analogues. At higher CO2 densities all noble gases expressed a significant deviation from predicted partition coefficients. At the highest density (656 kg/m3) helium values decreased by -54% (i.e. reduced solubility within CO2) while argon, krypton and xenon values increased by 76%, 106% and 291% respectively. These deviations are due to supercritical CO2 acting as a polar solvent, the solvation power of which increases as a function of density. Polarisation is induced in each noble gas within this solvent based on their respective polarisabilities. Hence xenon, krypton and argon become more easily solvated as a function of CO2 density while solvating helium becomes harder. These deviation trends are well described using a second order polynomial. This fit defines a deviation coefficient which can be used to adapt low pressure partition coefficients to allow accurate predictions of partitioning within highly dense CO2 phases. Concurrently a Gibbs Ensemble Monte Carlo (GEMC) molecular model was iteratively developed to reproduce noble gas behaviour within these experimental systems. By optimising noble gas-water interactions a pure noble gas-water system was constructed for each noble gas at low pressure which replicated published partition coefficients. These optimised interactions were subsequently applied to low pressure CO2-H2O systems where partition coefficients were derived by calculating excess chemical potentials of noble gases in each phase. Again a good agreement was observed with published values. When the model was applied to the experimental conditions however, a poor agreement with the experimental values was observed. Instead simulated values replicated the low pressure Crovetto et al. and Smith datasets (Crovetto et al., 1982; Smith, 1985). This was due to no CO2-noble gas polarisation terms being included in the current iteration of the model. By including this within the model in the future a full reconciliation between the datasets is expected.