Summary:This thesis presents the technology qualification plan for the integrated gasification combined cycle power plant (IGCC) with carbon dioxide capture based on DNV recommendations. Objectives of the thesis work were development of a qualification plan, heat balance, material balance and performance characteristics for IGCC with CO2 capture. GT PRO software by thermoflow was used for the development of heat balance, material balance and performance characteristics of power plant.IGCC with pre-combustion capture is a process of generating power with very low CO2 emissions. The IGCC process gasifies coal to a syngas, converts the CO to CO2 in the shift reactors, separates the CO2 in the capture subsystem, and the resulting fuel is used for the gas turbine (GT) in a combined cycle setup. A comparison is also made between the enriched air blown gasification combined cycle power plant with CO2 capture and shell gasification combined cycle power plant with CO2 capture. For the case of this thesis, technology qualification steps obtained from DNV guidelines are implemented on the enriched air blown integrated gasification power plant with CO2 capture. First step of the technology qualification was to establish a qualification basis for the IGCC power plant with CO2 capture. In this step detailed process description of power plant is done in order to define what technology should do and what its functional requirements are?Next step of the technology qualification was technology assessment. The main purpose of this step was to divide the IGCC power plant with CO2 capture into manageable elements that involve the aspects of new technology and identify key challenges and uncertainties associated with those novel elements.Threat assessment was the third step in the technology qualification. Risks and failure modes associated with the commercialization of IGCC with CO2 capture are identified by applying risk assessment techniques like (Failure Mode Effect & Criticality Analysis (FMECA) and Hazard and Operability Analysis (Hazop). Analysis of variance was used in order to give priority to more critical failure modes.Faiure modes like surge problem of gas turbine,fouling,metal dusting and tube vibration for the heat exchanger, deactivation of catalyst for shift reactor, maldistribution of the solvent for the absorber, contaminated supply of steam to steam turbine have been identified.Qualification plans were developed for the identified failure modes of concern obtained from FMECA and Hazop analysis .The main objective of this step was to select qualification activities that adequately address the identified failure modes of concern with respect to its risk and determination of sufficient performance margins. Activities like integration of gas turbine to air separation unit, chemical treatment of water in order to avoid contaminated supply of water to HRSG and contaminated supply of steam to steam turbine, better understanding of distributor design and packing development for the absorber were suggested.After the selection of these qualification activities, execution of selected qualification activities was done in a systematic manner to document performance margins for the failure modes of concern.Last step of the technology qualification plan was concept improvement. The objective of the concept improvement step was to implement improvements that have been found necessary or beneficial during the failure mode identification and risk ranking or in the performance assessment.The focus of this work was to reduce uncertainties in these parameters in order to improve the confidence in the IGCC power plant with CO2 capture.

Gas liquid separation is a critical operation in many industries, including the gas and oil industry. In fact, costly equipment like heat exchangers and compressors rely on the good performance of gas scrubbers. In the particular case of Norway, most of these operations are offshore where the plot area is critical. On the other hand, the separation of liquid droplets from the gas stream is generally performed in bulky and heavy pressure vessels. More compact technologies are emerging though. However, it is becoming difficult to select the appropriate separator and it is required engineering experience. Therefore, the objective of this project is to develop mathematical models for selected technologies to facilitate the selection. The technologies selected were the traditional knitted mesh separator and the recent multi-cyclone scrubber. The models provide the basic dimensions, weight, purchase and installed costs for both scrubbers. The results of both models were compared and extrapolated to hypothetical situations to establish when a compact technology becomes competitive. For this comparison, gas load factor and costs per flow rate were used. In fact the vessel compactness is related to the former. Therefore, it is intended to have values much higher than 0.107 m/s corresponding to traditional separators at atmospheric pressure. In fact, a factor slightly higher than 0.14 m/s would make very competitive multi-cyclones; which can be achieved at pressures higher than 70-80 bar. Furthermore, technologies with factors up 0.5 to 1 m/s might be much more attractive. Nevertheless, there would be restrictions in achieving the maximum gas load factor expected.

The global use of natural gas is growing quickly. This is primarily attributed to its favorable characteristics and to the environmental advantages it enjoys over other fossil fuels such as oil and coal. One of the key challenges in supplying natural gas is the form (phase) at which it should be delivered. Natural gas may be supplied to the consumers as a compressed gas through pipelines. Another common form is to be compressed, refrigerated and supplied as a liquid known as liquefied natural gas (LNG). When there is a considerable distance involved in transporting natural gas, LNG is becoming the preferred method of supply because of technical, economic, and political reasons. Thus, LNG is expected to play a major role in meeting the global energy demands. This work addresses the simulation and optimization of an LNG plant. First, the process flowsheet is constructed based on a common process configuration. Then, the key units are simulated using ASPEN Plus to determine the characteristics of the various pieces of equipment and streams in the plant. Next, process integration techniques are used to optimize the process. Particular emphasis is given to energy objectives through three activities. First, the synthesis and retrofitting of a heat-exchange network are considered to reduce heating and cooling utilities. Second, the turbo-expander system is analyzed to reduce the refrigeration consumption in the process. Third, the process cogeneration is introduced to optimize the combined heat and power of the plant. These activities are carried out using a combination of graphical, computeraided, and mathematical programming techniques. A case study on typical LNG facilities is solved to examine the benefits of simulation and integration of the process. The technical, economic, and environmental impact of the process modifications are also discussed.

We have developed a new automatic apparatus for the measurement of the phase equilibrium and pVT properties of natural gas mixtures in our laboratory. Based on the isochoric method, the apparatus can operate at temperature from 200 K to 500 K at pressures up to 35 MPa, and yield absolute results in fully automated operation. Temperature measurements are accurate to 10 mK and pressure measurements are accurate to 0.002 MPa. The isochoric method utilizes pressure versus temperature measurements along an isomole and detects phase boundaries by locating the change in the slope of the isochores. The experimental data from four gas samples show that cubic equations of state, such as Peng-Robinson and Soave-Redich-Kwong have 1-20% errors in predicting hydrocarbon mixture dew points. The data also show that the AGA 8-DC92 equation of state has errors as large as 0.6% when predicting hydrocarbon mixture densities when its normal composition range is extrapolated.

Large volumes of natural gas exist in tight fissured reservoirs. Hydraulic fracturing is one of the main stimulating techniques to enhance recovery from these fractured reservoirs. Although hydraulic fracturing has been used for decades for the stimulation of tight gas reservoirs, a thorough understanding of the interaction between induced hydraulic fractures and natural fractures is still lacking. Recent examples of hydraulic fracture diagnostic data suggest complex, multi-stranded hydraulic fracture geometry is a common occurrence. The interaction between pre-existing natural fractures and the advancing hydraulic fracture is a key condition leading to complex fracture patterns. Large populations of natural fractures that exist in formations such as the Barnett shale are sealed by precipitated cements which could be quartz, calcite, etc. Even though there is no porosity in the sealed fractures, they may still serve as weak paths for fracture initiation and/or for diverting the path of the growing hydraulic fractures. Performing hydraulic fracture design calculations under these complex conditions requires modeling of fracture intersections and tracking fluid fronts in the network of reactivated fissures. In this dissertation, the effect of the cohesiveness of the sealed natural fractures and the intact rock toughness in hydraulic fracturing are studied. Accordingly, the role of the pre-existing fracture geometry is also investigated. The results provide some explanations for significant differences in hydraulic fracturing in naturally fractured reservoirs from non-fractured reservoirs. For the purpose of this research, an extended finite element method (XFEM) code is developed to simulate fracture propagation, initiation and intersection. The motivation behind applying XFEM are the desire to avoid remeshing in each step of the fracture propagation, being able to consider arbitrary varying geometry of natural fractures and the insensitivity of fracture propagation to mesh geometry. New modifications are introduced into XFEM to improve stress intensity factor calculations, including fracture intersection criteria into the model and improving accuracy of the solution in near crack tip regions. The presented coupled fluid flow-fracture mechanics simulations extend available modeling efforts and provide a unified framework for evaluating fracture design parameters and their consequences. Results demonstrate that fracture pattern complexity is strongly controlled by the magnitude of in situ stress anisotropy, the rock toughness, the natural fracture cement strength, and the approach angle of the hydraulic fracture to the natural fracture. Previous studies (mostly based on frictional fault stability analysis) have concentrated on predicting the onset of natural fracture failure. However, the use of fracture mechanics and XFEM makes it possible to evaluate the progression of fracture growth over time as fluid is diverted into the natural fractures. Analysis shows that the growing hydraulic fracture may exert enough tensile and/or shear stresses on cemented natural fractures that they may be opened or slip in advance of hydraulic fracture tip arrival, while under some conditions, natural fractures will be unaffected by the hydraulic fracture. A threshold is defined for the fracture energy of cements where, for cases below this threshold, hydraulic fractures divert into the natural fractures. The value of this threshold is calculated for different fracture set orientations. Finally, detailed pressure profile and aperture distributions at the intersection between fracture segments show the potential for difficulty in proppant transport under complex fracture propagation conditions. Whether a hydraulic fracture crosses or is arrested by a pre-existing natural fracture is controlled by shear strength and potential slippage at the fracture intersections, as well as potential debonding of sealed cracks in the near-tip region of a propagating hydraulic fracture. We introduce a new more general criterion for fracture propagation at the intersections. We present a complex hydraulic fracture pattern propagation model based on the Extended Finite Element Method as a design tool that can be used to optimize treatment parameters under complex propagation conditions. / text

The anode material in a conventional design of solid oxide fuel cell (SOFC) operating above 1123 K is typically made from NiO/Zirconia. NiO/Zirconia anodes are known to perform well in hydrogen but exhibit difficulties when natural gas is used as a fuel. Natural gas is much cheaper than hydrogen and widely available but causes carbon deposition and deactivation of the NiO/Zirconia SOFC anode. One objective of this work was to prepare and characterize NiO/Zirconia anodes both as powders and as applied to extruded zirconia tubes. The problem of carbon deposition when NiO/Zirconia anodes operate in methane, the main component of natural gas, was investigated. Another aim was to address the problem of coking with an effort to moderate carbon deposition by using additives to the NiO/Zirconia anode. Temperature programmed reduction (TPR) was used to study the reaction characteristicso f NiO/Zirconia anodes.T he carbon depositedo n thesea nodesa fter methane decomposition and reforming was characterized using temperature programmed oxidation (TPO). The anodes were placed in a reactor (stainless-steel, alumina or zirconia) tube in a test assembly developed for an extruded tubular SOFC. The reactor inlet was connected to a flexible gas handling system and the exhaust to a continuously sampling mass spectrometer. This system also allowed simultaneous study of electrical and catalytic measurementsThe various conditions for methane reforming have been shown to influence the character of carbon deposited and the quantity deposited. Conditions such as anode calcination temperature, anode reduction regime, reforming temperature and reforming time have all been shown to influence the reactions occuring on the anode including carbon deposition, subsequently characterized by TPO. NiO/Zirconia powders have also been shown to behave differently from NiO/Zirconia anodes adhered to zirconia tubes. An alkali metal additive has been shown to moderate carbon deposition and improve cell performance. Small additions of Li, typically 1 mol %, to the Ni/Zirconia anode cause a decrease in carbon deposition after reforming at temperatures of 1123 K and 1173 K. The activation energy of surface carbon removed by oxygen is lowered by approximately 50 kJ mot' for the 1 mol % Li doped Ni/Zirconia anode compared to the undoped powder. Anodes doped with Li displayed greater cell performances. The improvements seen with these additives show that their use could offer a viable alternative to conventional anodes in current SOFC systems. Tubular solid oxide fuel cells have been tested in a custom built rig whereby electronic and catalytic measurements can be sampled simultaneously. This was used to monitor the influence of drawing current on the reactions occurring on the anode. The presence of alkali Li on the doped Ni anode surface has been shown to interfere with surface reactions under electrochemical load/steam reforming

This thesis examines the prospect of structure H (sH) hydrate to be exploited for methane storage. The methane content in the hydrate, hydrate kinetics and conversion rates are areas of particular importance. Experiments and theory are employed at the macroscopic and molecular levels to study the relevant phenomena. sH hydrate was successfully synthesized from ice particles with full conversion achieved within a day when thermal ramping above the ice melting point was applied. It was found that a polar guest (tert-butyl methyl ether / TBME) wets ice more extensively compared to two hydrophobic guests (neo-hexane / NH and methyl-cyclohexane / MCH). TBME also has much higher solubility in water. Consequently, the system with TBME was found to exhibit the highest initial hydrate formation rate from ice particles or in water in a well stirred vessel. However, the rate with the hydrophobic guests was the fastest when the temperature exceeded the ice point. Thus, the applied temperature ramping compensated the slow kinetics below the ice point for the hydrophobic guests and allowed faster overall conversion than the polar guest. Structure, cage occupancy, composition and methane content in the hydrate were also determined by employing different techniques and the results were found to be consistent. It was found that the methane content in structure H hydrate with TBME was the smallest (103-125 v/v) whereas that with NH was 130-139 (v/v) and that with MCH was 132-142 (v/v). The methane content in structure II hydrate by using propane (C₃H₈) and tetrahydrofuran (THF) as the large guest molecule were also estimated. Optimal methane content was found at approximately 100 (v/v) for both C₃H₈ and THF systems with the large guest concentrations at 1% for C₃H₈ (10°C) and 1% for THF (room temperature). The gas content is of course lower than that for structure I hydrate (170 v/v) but one should consider the fact that the hydrate formation conditions are much lower (less than 1 MPa). Finally, MD simulations revealed for the first time the formation of defects in the cavities for the TBME/methane/water (sH hydrate) system which may affect hydrate stability and kinetics.

This study investigates the performance of a hybrid turboexpander and fuel cell (HTEFC) system for power recovery at natural gas pressure reduction stations. Simulations were created to predict the performance of various system configurations. Natural gas is transported at high pressure across large distances. The pressure of the natural gas must be reduced before it is delivered to the consumer. Natural gas pressure reduction is typically achieved using pressure reduction throttling valves. In a limited number of cases pressure reduction is achieved using a turboexpander. This method has the added bonus of power generation. There is a considerable temperature drop associated with the turboexpander process. Preheating is required in many cases to avoid undesirable effects of a low outlet temperature. This preheating is typically done using gas fired boilers. The hybrid system developed by Enbridge and Fuel Cell Energy is a new approach to this problem. In this system a Molten Carbonate Fuel Cell (MCFC) running on natural gas is used in conjunction with the turbine to preheat the gas and provide additional low emission electrical power Various system configurations were simulated and factors affecting the overall performance of the systems were investigated. Power outputs, fuel requirements and efficiencies of various system configurations were found using typical gas flow variation data. The simulation was performed using input data from the current city gate pressure reduction station operated by Utilities Kingston. Using the data provided by Utilities Kingston the performance of various potential HTEFC system configurations were compared. This thesis illustrates the benefits of using this type of analysis in a feasibility study of future HTEFC systems for power recovery at natural gas pressure reduction stations. Improvements could be made to the accuracy of the simulation results by increasing the complexity of the individual component models. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-11-12 18:35:30.266

Petrophysical evaluation of the Albian age gas bearing sandstone reservoirs of the O-M field, Offshore South Africa has been performed. The main goal of the thesis is to evaluate the reservoir potentials of the field through the integration and comparison of results from core analysis, production data and petrography studies for the evaluation and correction of key petrophysical parameters from wireline logs which could be used to generate an effective reservoir model. A total of ten wells were evaluated and twenty eight sandstone reservoirs were encountered of which twenty four are gas bearing and four are wet within the Albian age depth interval of 2800m to 3500m. Six lithofacies (A1, A2, A3, A4, A5 and A6) were grouped according to textural and structural features and grain size from the key wells (OP1, OP2 and OP3). Facies A6 was identified as non reservoir rock in terms of reservoir rock quality and facies A1 and A2 were regarded as the best reservoir rock quality. This study identifies the different rock types that comprise reservoir and non reservoirs. Porosity and permeability are the key parameters for identifying the rock types and reservoir characterization.

No description available.