Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xii, 102 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 80-81).

Fossil fuels continue to deplete with use as they are irreplaceable. In addition, the environmental impact with the continuous use of these conventional fuels has generated global concern due to the production of harmful emission gases. An alternative source of energy has become inevitable. Technological advancements in the area of biomass use for both aviation and power generation are at different levels of development. There is however the need for an integrated approach to assess gas turbine engine behaviour in terms of performance, emission and economics when they are running on biofuels. The current research work is concerned with finding alternative fuel resources for use on stationary gas turbine engines for power generation with the necessary identification of suitable biofuels using a multidisciplinary approach. A techno-economic, environmental and risk assessment (TERA) model comprising the performance, emissions, economics and risk modules has been developed. There had been several simulations of two gas turbine engines (GTEs) to ascertain the effects of both ambient and operating conditions and the effect of fuel types on the engines. These simulations were done with the use of an in-house code-the Turbomatch and a code developed for the steam cycle which is employed for the combined cycle simulation. Cont/d.

Integrated Gasification Combined Cycle (IGCC) power plants have been considered as one of the best options for energy production in an environmental friendly manner. IGCC power plants are demonstrating better results, both in terms of plant performance and economics, when compared to a Pulverised Coal (PC) power plant with CO2 capture. The additional components required for an IGCC power plant when it is desired to operate in CO2 capture mode, give research potential with respect to an improved IGCC power plant performance. The IGCC power plant design framework studied and developed was based in DOE/NETL report and is presented. The conventional and CO2 capture IGCC power plants have been benchmarked in rigorous process flow diagrams developed using the commercial software Honeywell UniSim Design R400. As an essential part of the Innovative Gas Separations for Carbon Capture project (IGSCC EPSRC – EP/G062129/1) predictive simulation tools were produced to investigate the IGCC performance. The case studies considered include different gasification options for non-capture and carbon capture IGCCs, with a two stage Selexol process for the CO2 capture cases. Particular effort has been made to produce an accurate simulation component to describe the behaviour of the syngas in the Selexol solvent. The two stage Selexol configuration was investigated in detail and novel schemes are presented. No similar approaches have been reported in the literature, in terms of the proposed configuration and the capture efficiency. Moreover, innovative CO2 capture schemes incorporating combined units of physical absorption and membranes have been examined with respect to the power plant’s performance. In this thesis, contrary to other studies, all simulations cases have been conducted in unified flow diagrams. The results presented include overall investigations and can be a helpful tool for engineers and stakeholders in the decision making process.

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xii, 121 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 117-119).

Fossil fuels continue to deplete with use as they are irreplaceable. In addition, the environmental impact with the continuous use of these conventional fuels has generated global concern due to the production of harmful emission gases. An alternative source of energy has become inevitable. Technological advancements in the area of biomass use for both aviation and power generation are at different levels of development. There is however the need for an integrated approach to assess gas turbine engine behaviour in terms of performance, emission and economics when they are running on biofuels. The current research work is concerned with finding alternative fuel resources for use on stationary gas turbine engines for power generation with the necessary identification of suitable biofuels using a multidisciplinary approach. A techno-economic, environmental and risk assessment (TERA) model comprising the performance, emissions, economics and risk modules has been developed. There had been several simulations of two gas turbine engines (GTEs) to ascertain the effects of both ambient and operating conditions and the effect of fuel types on the engines. These simulations were done with the use of an in-house code-the Turbomatch and a code developed for the steam cycle which is employed for the combined cycle simulation. Cont/d.

Thesis (M.E.)--University of Canterbury, 2008. / Typescript (photocopy). Includes bibliographical references (p. 194-196). Also available via the World Wide Web.

The integrated gasification combined cycle (IGCC) is the most environmentally friendly coal-fired power generation technology that offers near zero green house gas emissions. This technology has higher thermal efficiency compared to conventional coal-fired power generation plants and uses up to 50% less water. This work involves the optimization of IGCC power plants by applying process integration techniques to maximize the use of energy available within the plant. The basis of this project was the theoretical investigations which showed that optimally designed and operated IGCC plants can achieve overall thermal efficiencies in the regions of 60%. None of the current operating IGCC plants approach this overall thermal efficiency, with the largest capacity plant attaining 47%. A common characteristic in most of these IGCC plants is that an appreciable amount of energy available within the system is lost to the environment through cold utility, and through plant irreversibility to a smaller extent. This work focuses on the recovery of energy, that is traditionally lost as cold utility, through application of proven process integration techniques. The methodology developed comprises of two primary energy optimization techniques, i.e. pinch analysis and the contact economizer system. The idea behind using pinch analysis was to target for the maximum steam flowrate, which will in turn improve the power output of the steam turbine. An increase in the steam turbine power output should result in an increase in the overall thermal efficiency of the plant. The contact economizer system is responsible for the recovery of low potential heat from the gas turbine exhaust en route to the stack to heat up the boiler feed water (BFW). It was proven in this work that a higher BFW enthalpy results in a higher overall efficiency of the plant. A case study on the Elcogas plant illustrated that the developed method is capable of increasing the gross efficiency from 47% to 55%. This increase in efficiency, however, comes at an expense of increased heat exchange area required to exchange the extra heat that was not utilized in the preliminary design. / Dissertation (MEng)--University of Pretoria, 2011. / Chemical Engineering / unrestricted

ABSTRACT REMOVAL OF HYDROGEN SULFIDE BY REGENERABLE METAL OXIDE SORBENTS Karayilan, Dilek M.S., Department of Chemical Engineering Supervisor : Prof. Dr. Timur Dogu Co-Supervisor: Prof. Dr. G&uuml / lSen Dogu June 2004, 166 pages High-temperature desulfurization of coal-derived fuel gases is an essential process in advanced power generation technologies. It may be accomplished by using metal oxide sorbents. Among the sorbents investigated CuO sorbent has received considerable attention. However, CuO in uncombined form is readily reduced to copper by the H2 and CO contained in fuel gases which lowers the desulfurization efficiency. To improve the performance of CuO-based sorbents, they have been combined with other metal oxides, forming metal oxide sorbents. Sulfidation experiments were carried out at 627 oC using a gas mixture composed of 1 % H2S and 10 % H2 in helium. Sorbent regeneration was carried out in the same reactor on sulfided samples at 700 oC using 6 % O2 in N2. Total flow rate of gas mixture was kept at 100 ml/min in most of the experiments. In this study, Cu-Mn-O, Cu-Mn-V-O and Cu-V-O sorbents were developed by using complexation method. Performance of prepared sorbents were investigated in a fixed-bed quartz microreactor over six sulfidation/regeneration cycles. During six cycles, sulfur retention capacity of Cu-Mn-O decreased slightly from 0.152 to 0.128 (g S)/(g of Sorbent) while some decrease from 0.110 to 0.054 (g S)/(g of Sorbent) was observed with Cu-Mn-V-O. Cu-V-O showed a very good performance in the first sulfidation and excessive thermal sintering in the first regeneration prevented further testing. Sulfur retention capacity of Cu-V-O was calculated as 0.123 (g S)/(g of Sorbent) at the end of the first sulfidation. In addition, SO2 formation in sulfidation experiments was observed only with Cu-V-O sorbent.

M.Sc. / The increased demand for electricity in South Africa is expected to exceed supply between 2004 and 2007. Electricity supply options in the country would be further complicated by the fact that older power stations would reach the end of their design life beyond the year 2025. In light of this and considering the long lead times required for the commissioning of new plants, new power supply options need to be proactively investigated. The environmental impacts associated with coal-fired generation of electricity have resulted in increased global concern over the past decade. To reduce these impacts, new technologies have been identified to help provide electricity from fossil fuels. The alternatives considered are gas-fired generation technologies and the Integrated Gasification Combined Cycle (IGCC). This study attempts to document and understand the environmental aspects related to gas-fired and IGCC electricity generation and evaluate their advantages in comparison to conventional pulverised coal fired power generation. The options that could be utilised to make fossil fuel electricity generation more environmentally friendly, whilst remaining economically feasible, were also evaluated. Gas-fired electricity generation is extremely successful as electricity generation systems in the world due to inherently low levels of emissions, high efficiencies, fuel flexibility and reduced demand on finite resources. Associated benefits of a Combined Cycle Gas Turbine (CCGT) are lower operating costs due to the reduced water consumption, smaller equipment size and a reduction in the wastewater that has to be treated before being returned to the environment. A CCGT plant requires less cooling water and can be located on a smaller area than a conventional Pulverised Fuel (PF) power station of the same capacity. All these factors reduce the burden on the environment. A CCGT also employs processes that utilises the energy of the fuel more efficiently, with the current efficiencies approaching 60%. Instead of simply being discharged into the atmosphere, the gas turbines’ exhaust gas heat is used to produce additional output in combination with a Heat Recovery Steam Generator (HRSG) and a steam turbine. Furthermore, as finite resources become increasingly scarce and energy has to be used as wisely as possible, generating electricity economically and in an ecologically sound manner is of the utmost importance. The clean, reliable operation of gas-fired generation systems with significantly reduced noise levels and their compact design makes their operation feasible in heavily populated areas, where electricity is needed most. At the same time, energy can be consumed in whatever form needed, i.e. as electricity, heat or steam. The dependence of the South African economy on cheap coal ensures that it will remain a vital component of future electricity generation options in the country. This dominance of coal-fired generation in the country is responsible for South Africa’s title as the largest generator of carbon dioxide (CO2) emissions on the continent and the country could possibly be requested to reduce its CO2 emissions at the next international meeting of signatories to the Kyoto Protocol. Carbon dioxide emissions can be reduced by utilising gas-fired generation technologies. However, the uncertainty and costs associated with natural gas in South Africa hampers the implementation of this technology. There are currently a number of initiatives surrounding the development of natural gas in the country, viz. the Pande and Temane projects in Mozambique and the Kudu project in Namibia, and this is likely to positively influence the choice of fuel utilised for electricity generation in the future. The economic viability of these projects would be further enhanced through the obtaining of Clean Development Mechanism (CDM) credits for greenhouse gases (GHG) emissions reduction. Alternatively, more efficient methods of generating electricity from coal must be developed and implemented. IGCC is capable of achieving this because of the high efficiencies associated with the combined cycle component of the technology. These higher efficiencies result in reduced emissions to the atmosphere for an equivalent unit of electricity generated from a PF station. An IGCC system can be successful in South Africa in that it combines the benefits of utilising gas-fired electricity generation systems whilst utilising economically feasible fuel, i.e. coal. IGCC systems can economically meet strict air pollution emission standards, produce water effluent within environmental limits, produce an environmentally benign slag, with good potential as a saleable by-product, and recover a valuable sulphur commodity by-product. Life-cycle analyses performed on IGCC power plants have identified CO2 release and natural resource depletion as their most significant positive lifecycle impacts, which testifies to the IGCC’s low pollutant releases and benign by-products. Recent studies have also shown that these plants can be built to efficiently accommodate future CO2 capture technology that could further reduce environmental impacts. The outstanding environmental performance of IGCC makes it an excellent technology for the clean production of electricity. IGCC systems also provide flexibility in the production of a wide range of products including electricity, fuels, chemicals, hydrogen, and steam, while utilizing low-cost, widely available feedstocks. Coal-based gasification systems provide an energy production alternative that is more efficient and environmentally friendly than competing coalfuelled technologies. The obstacle to the large-scale implementation of this technology in the country is the high costs associated with the technology. CDM credits and by-products sales could possible enhance the viability of implementing these technologies in South Africa.

Hydrocracking and hydrotreating are bitumen upgrading technologies designed to enhance fuel quality by decreasing its density, viscosity, boiling point and heteroatom content via hydrogen addition. The aim of this thesis is to model and simulate an upgrading and integrated gasification combined cycle then to evaluate the feasibility of integrating slurry hydrocracking, trickle-bed hydrotreating and residue gasification using the Aspen HYSYS® simulation software. The close-coupling of the bitumen upgrading facilities with gasification should lead to a hydrogen, steam and power self-sufficient upgrading facility with CO2 capture. Hydrocracker residue is first withdrawn from a 100,000 BPD Athabasca bitumen upgrading facility, characterized via ultimate analysis and then fed to a gasification unit where it produces hydrogen that is partially recycled to the hydrocracker and hydrotreaters and partially burned for power production in a high hydrogen combined cycle unit. The integrated design is simulated for a base case of 90% carbon capture utilizing a monoethanolamine (MEA) solvent, and compared to 65% and no carbon capture scenarios. The hydrogen production of the gasification process is evaluated in terms of hydrocracker residue and auxiliary petroleum coke feeds. The power production is determined for various carbon capture cases and for an optimal hydrocracking operation. Hence, the feasibility of the integration of the upgrading process and the IGCC resides in meeting the hydrogen demand of the upgrading facility while producing enough steam and electricity for a power and energy self-sufficient operation, regardless of the extent of carbon capture.