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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.

<p>Biomass is one of the main natural resources in Sweden.Increased utilisation of biomass for energy purposes incombined heat and power (CHP) plants can help the country meetits nuclear phase-out commitment. The present low-CO2 emissioncharacteristics of the Swedish electricity production system(governed by hydropower and nuclear power) can be retained onlyby expansion of biofuels in the CHP sector. Domestic Swedishbiomass resources are vast and renewable, but not infinite.They should be utilised as efficiently as possible in order tomeet the conditions for sustainability in the future.Application of efficient power generation cycles at low cost isessential for meeting this challenge. This applies also tomunicipal solid waste (MSW) incineration with energyextraction, which is to be preferred to landfilling.</p><p>Modern gas turbines and internal combustion engines firedwith natural gas have comparatively low installation costs,good efficiency characteristics and show reliable performancein power applications. Environmental and source-of-supplyfactors place natural gas at a disadvantage as compared tobiofuels. However, from a rational perspective, the use ofnatural gas (being the least polluting fossil fuel) togetherwith biofuels contributes to a diverse and more secure resourcemix. The question then arises if both these fuels can beutilised more efficiently if they are employed at the samelocation, in one combined cycle unit.</p><p>The work presented herein concentrates on the hybriddual-fuel combined cycle concept in cold-condensing and CHPmode, with a biofuel-fired bottoming steam cycle and naturalgas fired topping gas turbine or engine. Higher electricalefficiency attributable to both fuels is sought, while keepingthe impact on environment at a low level and incorporating onlyproven technology with standard components. The study attemptsto perform a generalized and systematic evaluation of thethermodynamic advantages of various hybrid configurations withthe help of computer simulations, comparing the efficiencyresults to clearly defined reference values.</p><p>Results show that the electrical efficiency of hybridconfigurations rises with up to 3-5 %-points in cold-condensingmode (up to 3 %-points in CHP mode), compared to the sum of twosingle-fuel reference units at the relevant scales, dependingon type of arrangement and type of bottoming fuel. Electricalefficiency of utilisation of the bottoming fuel (biomass orMSW) within the overall hybrid configuration can increase withup to 8-10 %-points, if all benefits from the thermalintegration are assigned to the bottoming cycle and effects ofscale on the reference electrical efficiency are accounted for.All fully-fired (windbox) configurations show advantages of upto 4 %-points in total efficiency in CHP mode with districtheating output, when flue gas condensation is applied. Theadvantages of parallel-powered configurations in terms of totalefficiency in CHP mode are only marginal. Emissions offossil-based CO2 can be reduced with 20 to 40 kg CO2/MWhel incold-condensing mode and with 5-8 kg CO2 per MWh total outputin CHP mode at the optimum performance points.</p><p>Keywords: Biomass, Municipal Solid Waste (MSW), Natural Gas,Simulation, Hybrid, Combined Cycle, Gas Turbine, InternalCombustion Engine, Utilization, Electrical Efficiency, TotalEfficiency, CHP.</p>

Natural gas has become the UK’s foremost primary energy source, providing some 39% of our energy needs. The National Transmission System (NTS) has developed from its humble beginnings when natural gas was first discovered in the North Sea in the 1960s to become a complex interconnected network delivering up to 550 million cubic meters of gas daily. Gas has also become an increasingly important energy source for power generation, currently generating 35% of our electricity. This presents major challenges for the planning and operation of both the electricity and gas networks as their interdependence grows into the future. With the government’s goal of drastically reducing emissions from power generation by 2020, Combined Cycle Gas Turbine units, and therefore the NTS, will have to offer a new degree of flexibility to quickly respond to the intermittency of the growing penetration of wind generation on the electricity transmission system. Coupling this with the decline in the UK natural gas resources resulting in the NTS becoming reliant on imports to meet demand, it is becoming increasingly difficult to decouple the security of the gas supply from the security of the electricity supply in the UK. This study presents the modelling challenge of assessing this growing interaction and provides a robust methodology for completing a security analysis using detailed network models of the UK gas and electricity transmission systems. A thorough investigation of the intraday operation of the two systems in 2020 is presented given the growth of wind generation in the UK. The results are analysed and the implications for combined modelling and assessment are discussed as we enter a new era for UK energy security.

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.

Orientador: José Luz Silveira / Resumo: As maiores restrições ambientais impostas por autoridades de todo o mundo, no sentido de buscar a redução dos níveis de emissões de poluentes, bem como a crescente escassez de recursos minerais como o petróleo, impõe a alguns países a real necessidade de investir em novas tecnologias que melhor aproveitem os recursos disponíveis com menos agressão ao meio ambiente aliado a maior geração de receita. Nesse sentido a tecnologia IGCC – Integrated Gasification Combined Cycle é apresentada como uma possibilidade para atingir estes objetivos, inclusive para países como o Brasil que dispõe de grandes reservas petrolíferas e que tem a necessidade de aumentar a produção de insumos como hidrogênio, vapor e energia elétrica. Este trabalho apresenta uma breve revisão da bibliografia sobre o refino de petróleo, sobre a gaseificação dos resíduos provenientes do refino e sobre a tecnologia IGCC em seus aspectos gerais, abordando os principais componentes do sistema e como esta tecnologia pode ser utilizada em uma planta de refino. Na sequência, as aplicações da tecnologia IGCC são exemplificadas com três exemplos reais em funcionamento no mundo. A refinaria do vale do Paraíba é utilizada como estudo de caso para a implantação de uma planta IGCC, utilizando 100% do coque verde de petróleo produzido como matéria prima para a gaseificação, tendo como objetivo a produção exclusiva de energia elétrica para a geração de dividendos à refinaria. A análise termodinâmica da planta apresentou eficiênci... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The greater environmental restrictions imposed by authorities around the world, in the sense of seeking to reduce levels of pollutant emissions, as well as the growing scarcity of mineral resources such as oil, impose on some countries the real need to invest in new technologies that best utilize available resources with less aggression to the environment combined with greater revenue generation. In this sense the Integrated Gasification Combined Cycle (IGCC) technology is presented as a possibility to achieve these objectives, including for countries such as Brazil that has large oil reserves and that has the need to increase its production of inputs such as hydrogen, steam and electricity. This paper presents a brief review of the literature on oil refining, gasification of waste from refining and IGCC technology in its general aspects, addressing the main components of the system and how this technology can be used in a refining plant. Following, the applications of the IGCC technology are exemplified with three real examples in operation in the world. The Paraíba Valley Refinery is used as a case study for the implementation of an IGCC plant, using 100% of the Petcoke produced as a raw material for gasification, with the objective of producing exclusively electric energy for generation of dividends to the refinery. The thermodynamic analysis of the plant presented net efficiency in electricity production of 41,2% with a production capacity of 260 MW. The economic analysis... (Complete abstract click electronic access below) / Mestre

This thesis covers the modelling of a Heat Recovery Steam Generator (HRSG) in a Combined Cycle Power Plant(CCPP). This kind of power plant has become more and more utilized because of its high efficiency and low emissions. The HRSG plays a central role in the generation of steam using the exhaust heat from the gas turbine. The purpose of the thesis was to develop efficient dynamic models for the physical components in the HRSG using the modelling and simulation software Dymola. The models are then to be used for simulations of a complete CCPP.The main application is to use the complete model to introduce various disturbances and study their consequences inthe different components in the CCPP by analyzing the simulation results. The thesis is a part of an ongoingdevelopment process for the dynamic simulation capabilities offered by the Solution department at SIT AB. First, there is a theoretical explanation of the CCPP components and control system included in the scope of this thesis. Then the development method is described and the top-down approach that was used is explained. The structure and equations used are reported for each of the developed models and a functional description is given. Inorder to ensure that the HRSG model would function in a complete CCPP model, adaptations were made and tuning was performed on the existing surrounding component models in the CCPP. Static verifications of the models are performed by comparison to Siemens in-house software for static calculations. Dynamic verification was partially done, but work remains to guarantee the validity in a wide operating range. As a result of this thesis efficient models for the drum boiler and its control system have been developed. An operational model of a complete CCPP has been built. This was done integrating the developed models during the work with this thesis together with adaptations of already developed models. Steady state for the CCPP model is achieved during simulation and various disturbances can then be introduced and studied. Simulation time for a typical test case is longer than the time limit that has been set, mainly because of the gas turbine model. When using linear functions to approximate the gas turbine start-up curves instead, the simulation finishes within the set simulation time limit of 5 minutes for a typical test case.

This work focuses on high-temperature kraft black liquor gasification in the presence of H2O and CO2 in a laboratory-scale Laminar Entrained-Flow Reactor (LEFR). The effects of gasification conditions on hydroxide formation, carbon gasification rate, carbonate carbon and fixed carbon levels, alkali metal and sulfur species retention, and char yield were studied at atmospheric pressure and at 900-1000oC, and at residence times of 0.5-1.5 s. The results suggest that carbon gasification rates may be enhanced in the presence of H2O and CO2, with fixed carbon conversions of up to 95% at the earliest residence times at 1000oC. CO2 and H2O gasifying agents cause a significant increase in carbonate formation, with 22% of the initial carbon input forming carbonate as compared to 16% with one gasifying agent. Carbonate levels increase to a maximum level and then decrease at 900oC, but at 1000oC, carbonate decomposition processes are more dominant and cause lower levels of carbonate even at early residence times. The results show that alkali metal retention is high until vaporization occurs after 1.4 s at 900oC and at early residence times at 1000oC. Moreover, the results indicate that sulfur retention is an exothermic process, as sulfur capture increases with temperature. At 900oC, no hydroxide is produced until after 1.4 s, but at 1000oC, hydroxide appears to form readily even at the earliest residence times studied. The char product yields a maximum mole percent of 18-19% hydroxide, starting at intermediate residence times at 1000oC. Generally, hydroxide is not produced until fixed carbon conversions approach 95%. The results can be explained in terms of the interactions of phenolate and carboxylate catalytic moieties in the char product. The hydroxide formation results suggest that it may be possible to develop a gasification-causticization process that does not require external chemicals and would make the energy-efficient and environmentally friendly black liquor gasification technology an economic reality.

Abstract In recent years, domestic energy policy has continuously changed, especially, after a liberalization of electric power market opened, resulting into the power industry proprietor expected to has a stable electric power supply systems, high power generation, high thermal efficiency and low heat rate. They will consistently devise a way to propose a strategy of improved or enhanced in the light of a competitive footstone for electric force market. About 90% worldwide and 65% domestic electricity are generated by the thermal power plants, where the energy source is obtained from burning the fossil fuels. Therefore, Increasing the power generation capacity of thermal power plants will substantially raise to the percent reserve margin of to be smaller than 12% over the years. In Taiwan, the ambient temperature is always higher than 30oC at summer. When gas turbine has operated during peak, gave rise to deteriorate its power generation capability and often actually generated power lower 10% than based on a design condition of ISO 15oC. This study adopts a way which is not same as conventional method increased power generation capability of the thermal power plants. In other word, reducing the inlet air temperature to gas turbine, it will increase the air flow mass rate and the generated-power capacity. By means of EPRI Gate Cycle Software constructing a typical combined-cycle power plant, at the same time, to simulate and to search out an effective operating control strategy for the power plant with GTIAC. Furthermore, applying the electric chiller and the absorption chiller to combined-cycle power plant as an inlet air cooling system use thermodynamic and engineering analysis to discuss an extent of energy utilizing, the valuability of energy application, to access the economic effect of investing equipment to acquire an optimal balance point. Selecting the inlet air temperature 15oC,10oC and comparing the thermal performance of electric chiller with that of absorption chiller. Then, proposing a feasible suggestion to treat as an important reference criteration of improving present power GENSET and planning to install a thermal power plant for the electric power proprietor.

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).