Turbine Combined Cycle Power Plants Research Articles

열병합 발전소의 구성안별 성능 평가 방안 - 플랜트 열성능 및 단순화 발전단가 분석

Thermodynamic and economic analyses of various types of gas turbine combined cycle power plants have been performed to establish criteria for optimization of power plants. The concept of efficiency, in terms of the difference in energy levels of electricity and heat, was introduced. The efficiency of power and heat generation by power plants with other purposes was estimated, and power generation costs were figured out for various types of combined heat and power plants(i.e., fired and unfired, condensing and non-condensing modes, single or double pressure HRSG).

Performance Entitlement of Supercritical Steam Bottoming Cycle

A supercritical steam bottoming cycle has been proposed as a performance enhancement option for gas turbine combined cycle power plants. The technology has been widely used in coal-fired steam turbine power plants since the 1950s and can be considered a mature technology. Its application to the gas-fired combined cycle systems presents unique design challenges due to the much lower gas temperatures (i.e., 650 °C at the gas turbine exhaust vis-à-vis 2000 °C in fossil fuel-fired steam boilers). Thus, the potential impact of the supercritical steam conditions is hampered to the point of economic infeasibility. This technical brief draws upon the second-law based exergy concept to rigorously quantify the performance entitlement of a supercritical high-pressure boiler section in a heat recovery steam generator utilizing the exhaust of a gas turbine to generate steam for power generation in a steam turbine.

Using coolant modulation and pre-cooling to avoid turbine blade overheating in a gas turbine combined cycle power plant fired with low calorific value gas

Overheating of turbine blades is one of the major concerns in using low calorific value fuels in gas turbines. In this work, we examined the deviation of operating conditions of a gas turbine fired with a low calorific value gas fuel, with a focus on the turbine blade temperatures. Several measures to suppress blade overheating were compared in terms of the power output and efficiency of the gas turbine combined cycle plant. Blade overheating can be prevented by decreasing the firing temperature without the need for hardware modifications, but the accompanying power reduction is considerable. As a remedy to this large reduction in power, modulation of the coolant supply to each blade row was simulated, and a much lower power penalty was observed. Moreover, pre-cooling of the coolant enhances the power output further by reducing the coolant supply. Pre-cooling recovers 80% of the available maximum augmentation of the combined cycle by simply switching the fuel from natural gas to low calorific value gas. Pre-cooling also provides higher overall combined cycle efficiency compared to under-firing.

Parameter Optimization CCPP and Coolant System Gas Turbine

Today most researchers optimize the parameters of cycles in combined cycle power plants without detailed calculations of the gas turbine flow path, which often involves separate optimization of the steam cycle and the gas turbine parameters, including the parameters of the gas turbine flow path that are usually known beforehand. This paper is the first to suggest a technique for coordinated optimization of combined cycle power plants, where both the parameters of the steam cycle in the combined cycle power plant and the parameters of the gas turbine, including the design parameters of its flow path, are optimized simultaneously. Based on the proposed technique we carried out optimization studies on the combined cycle power plant with optimum capacity. We also made optimization studies on the combined cycle power plant using the classical separate technique. The developed technique suggests an approach to the estimation of investment in gas turbine plants. This technique can be used to conduct studies on gas turbine plants and combined cycle power plants for different types and ways of cooling the gas turbine flow path. The presented data of optimization calculations show the advantages of optimizing combined cycle power plants using this technique as compared to the methods, where gas turbine and the steam cycle of the combined cycle power plant are optimized separately. The economic effect of applying the proposed technique is described.

A study on the evaluations of emission factors and uncertainty ranges for methane and nitrous oxide from combined-cycle power plant in Korea

In this research, in order to develop technology/country-specific emission factors of methane (CH4) and nitrous oxide (N2O), a total of 585 samples from eight gas-fired turbine combined cycle (GTCC) power plants were measured and analyzed. The research found that the emission factor for CH4 stood at “0.82 kg/TJ”, which was an 18 % lower than the emission factor for liquefied natural gas (LNG) GTCC “1 kg/TJ” presented by Intergovernmental Panel on Climate Change (IPCC). The result was 8 % up when compared with the emission factor of Japan which stands at “0.75 kg/TJ”. The emission factor for N2O was “0.65 kg/TJ”, which is significantly lower than “3 kg/TJ” of the emission factor for LNG GTCC presented by IPCC, but over six times higher than the default N2O emission factor of LNG. The evaluation of uncertainty was conducted based on the estimated non-CO2 emission factors, and the ranges of uncertainty for CH4 and N2O were between −12.96 and +13.89 %, and −11.43 and +12.86 %, respectively, which is significantly lower than uncertainties presented by IPCC. These differences proved that non-CO2 emissions can change depending on combustion technologies; therefore, it is vital to establish country/technology-specific emission factors.

Performance enhancement of GT-ST power plant with inlet air cooling using lithium bromide/water vapour absorption refrigeration system

Performance improvement techniques in power generation systems especially in gas turbine-steam turbine (GT-ST) combined cycle (CC) power plants by compressor inlet air cooling prove to be much improvising. In this work, the performance enhancement of CC power plant by inlet air cooling method using lithium bromide-water (LiBr/H2O) absorption refrigeration system powered by waste heat from heat recovery steam generator (HRSG) have been evaluated and analysed. The results show that CC output always increases but its efficiency increases at certain conditions with incorporating vapour absorption refrigeration (VAR) to CC plant. Coefficient of performance (COP) values of the single effect VAR system is around 0.9 for LiBr/H2O system. A low concentration for weak solution and a high concentration for strong solution have been recommended to get the maximum benefit. The simulated results of plant are validated by considering a case study of existed power plant located at Cochin, Kerala, India and found a close matching.

Development of Performance Deterioration Diagnosis Method for Gas Turbine Combined Cycle Power Plants

It is necessary to maintain or improve the thermal efficiency of actual thermal power generation plants from the viewpoint of environmental problems. When the thermal efficiency decreases, it is crucial to identify the performance deterioration factors by appropriate energy management. However, it is difficult to understand the internal state of such plants sufficiently and to determine performance deterioration factors only from operation data. In particular, investigating the performance deterioration factors is very difficult in gas turbine combined cycle (GTCC) power plants because the performance changes markedly depending on atmospheric conditions. Therefore, we develop a method based on heat and mass balance analysis to calculate the immeasurable quantity of state and the component performance values in GTCC power plants, and to correct them to the values under standard conditions using the performance function obtained from long-term operation data. From the results, we can identify the main factors affecting the thermal efficiency deterioration of GTCC power plants using this method.

Technologies for gas turbine power generation with CO2 mitigation

A review of the state of the art gas turbine power plants designs with CO2 capture was performed to set up a list of technologies to be considered in a conceptual process superstructure. It has been found that the efficiency and economics of carbon dioxide capture in gas turbine combined cycle power plants can be remarkably improved by introducing Flue Gas Recirculation (FGR) so as to increase the CO2 concentration in the flue gas and to reduce the volume of the flue gas treated in a CO2 capture plant. Thus, this process was chosen as the main focus of the thermo-economic modeling and the combustion system related experimental testing. Combustion studies were performed to quantify the impact of reduced oxygen content (caused by flue gas recirculation) on combustion stability and emission characteristics (NOx, CO). Tests were performed with methane, methane/ethane (simulated natural gas), methane/hydrogen and natural gas (as distributed in Switzerland) at different FGR ratios. For all conditions the addition of ethane or hydrogen shows beneficial effects (restoration of flame reactivity) on flame stability and CO emission. Using PSI’s high pressure test rig, it has been shown, that by redirecting up to 30% of exhaust gas volume back to the combustor, the CO2 concentration in the exhaust can be increased to 8% vol. while keeping the flame temperature constant (Tad=1750K) and meeting the emission requirements (CO, NOx< 25 ppm @ 15% O2). Benchmark tests of catalytic partial oxidation reactors were performed to determine whether sufficient H2 could be produced in situ by reaction of a slip stream of natural gas with extracted compressor oxidant. The work confirmed that FGR has the potential to significantly reduce the energy penalty connected with postcombustion carbon capture techniques and still meet the requirements on NOx and CO emissions.

S082012 次世代ガスタービン開発への取り組みと東北電力コンバインドサイクル発電プラントの歩み([S08201]高効率火力発電およびCCS技術)

As global warming becomes increasingly serious, resources and energy utilizations should be more efficient than before. Tohoku Electric Power Company, Inc. (Tohoku-EPCO) and Mitsubishi Heavy Industries, Ltd. (MHI) have started a study of next generation gas turbines to further improve the gas turbine combined cycle (GTCC) power plants efficiency. Tohoku-EPCO and MHI have invented a "closed circuit air cooling system" and a trial design of the closed circuit air cooled combustor is now being conducted as a collaborative project. Besides, the material technology development is being conducted for the further increase in the turbine Row 1 vane inlet temperature (TIT) in future.

The Elephant in the Room–Gas Turbine Power

This article presents an overview of gas turbine combined cycle (CCGT) power plants. Modern CCGT power plants are producing electric power as high as half a gigawatt with thermal efficiencies approaching the 60% mark. In a CCGT power plant, the gas turbine is the key player, driving an electrical generator. Heat from the hot gas turbine exhaust is recovered in a heat recovery steam generator, to generate steam, which drives a steam turbine to generate more electrical power. Thus, it is a combined power plant burning one unit of fuel to supply two sources of electrical power. Most of these CCGT plants burn natural gas, which has the lowest carbon content of any other hydrocarbon fuel. Their near 60% thermal efficiencies lower fuel costs by almost half compared to other gas-fired power plants. Their installed capital cost is the lowest in the electric power industry. Moreover, environmental permits, necessary for new plant construction, are much easier to obtain for CCGT power plants.

A Simple Parametric Model for the Analysis of Cooled Gas Turbines

A natural gas fired gas turbine combined cycle power plant is the most efficient option for fossil fuel based electric power generation that is commercially available. Trade publications report that currently available technology is rated near 60% thermal efficiency. Research and development efforts are in place targeting even higher efficiencies in the next two decades. In the face of diminishing natural resources and increasing carbon dioxide emissions, leading to greenhouse gas effect and global warming, these efforts are even more critical today than in the last century. The main performance driver in a combined cycle power plant is the gas turbine. The basic thermodynamics of the gas turbine, described by the well-known Brayton cycle, dictates that the key design parameters that determine the gas turbine performance are the cycle pressure ratio and maximum cycle temperature at the turbine inlet. While performance calculations for an ideal gas turbine are straightforward with compact mathematical formulations, detailed engineering analysis of real machines with turbine hot gas path cooling requires complex models. Such models, requisite for detailed engineering design work, involve highly empirical heat transfer formulations embedded in a complex system of equations that are amenable only to numerical solutions. A cooled turbine modeling system incorporating all pertinent physical phenomena into compact formulations is developed and presented in this paper. The model is fully physics-based and amenable to simple spreadsheet calculations while illustrating the basic principles with sufficient accuracy and extreme qualitative rigor. This model is valuable not only as a teaching and training tool, it is also suitable to preliminary gas turbine combined cycle design calculations in narrowing down the field of feasible design options.

Air Race

This article presents an overview of the existence and use of gas turbines in the past, present, and future. The article uses the data provided by Forecast International of Newtown, Conn., which covers both aviation and nonaviation gas turbine markets. The gas turbine has proven to be an example of technological evolution, where improvements in efficiency and reliability continue to amass, 70 years after its invention. Advanced technology developed in military jet engines has often migrated to commercial jet engines and nonaviation gas turbines, and improved their performance. Gas turbine combined-cycle power plants come in all sizes. The largest combined-cycle gas turbines are the H class machines made by GE and Siemens. Given the world’s current focus on sustainable or renewable energy, how do natural gas-fired gas turbines fit in? In some instances, renewable energy, such as solar or wind, just would not be practical without assistance from gas turbines. As power production moves tentatively into a low-carbon future, or as people look for more fuel-efficient ways to cross continents, it’s a sure bet that gas turbines will be there.

English

Fuel cells offer a more efficient and fuel flexible technology that produces heat and power with lower emissions. It is observed that by integrating fuel cells with the gas turbines, more than 70%thermal efficiency can be achieved from the combined cycle. This proves to be a better exergetic performance when compared to the conventional gas turbine plants. A Solid Oxide Fuel Cell-Gas Turbine combined cycle power plant is modeled and parametric exergy analysis is done to evaluate the energy efficiency, exergy efficiency and the exergy destruction of each component in the system. The effect of pressure ratio, turbine inlet temperature and ambient temperature on the performance of the system is investigated by using diesel and gasoline as fuels. The outcome of the modeled system reveals that SOFC and combustion chamber are the main sources of exergy destruction. At optimum pressure ratio, the total thermal efficiency using gasoline and diesel is found to be 71.36% and 70.72% while the exergy efficiency is found to be 66.53% and 66.76% respectively.

Syngas를 연료로 사용하는 발전용 가스터빈의 성능해석

Integrated Gasification Combined Cycle (IGCC) power plant converts coal to syngas, which is mainly composed of hydrogen and carbon monoxide, by the gasification process and produces electric power by the gas and steam turbine combined cycle power plant. The purpose of this study is to investigate the influence of using syngas in a gas turbine, originally designed for natural gas fuel, on its performance. A commercial gas turbine is selected and variations of its performance characteristics due to adopting syngas is analyzed by simulating off-design gas turbine operation. Since the heating value of the syngas is lower, compared to natural gas, IGCC plants require much larger fuel flow rate. This increases the gas flow rate to the turbine and the pressure ratio, leading to far larger power output and higher thermal efficiency. Examination of using two different syngases reveals that the gas turbine performance varies much with the fuel composition.

Performance improvement of combined cycle power plant based on the optimization of the bottom cycle and heat recuperation

Many F class gas turbine combined cycle (GTCC) power plants are built in China at present because of less emission and high efficiency. It is of great interest to investigate the efficiency improvement of GTCC plant. A combined cycle with three-pressure reheat heat recovery steam generator (HRSG) is selected for study in this paper. In order to maximize the GTCC efficiency, the optimization of the HRSG operating parameters is performed. The operating parameters are determined by means of a thermodynamic analysis, i.e. the minimization of exergy losses. The influence of HRSG inlet gas temperature on the steam bottoming cycle efficiency is discussed. The result shows that increasing the HRSG inlet temperature has less improvement to steam cycle efficiency when it is over 590°C. Partial gas to gas recuperation in the topping cycle is studied. Joining HRSG optimization with the use of gas to gas heat recuperation, the combined plant efficiency can rise up to 59.05% at base load. In addition, the part load performance of the GTCC power plant gets much better. The efficiency is increased by 2.11% at 75% load and by 4.17% at 50% load.

Performance effects of combined cycle power plant with variable condenser pressure and loading

Utility power producers are being driven by the inherently high efficiency and attractive installed cost of Combined Cycle Power Plants (CCPP) to consider them as the dominant choice for least-cost power. However, in a CCPP the power capability is significantly affected by the ambient temperature [Sue DC, Chuang CC, Lin PH. Performance improvement for gas turbine combined cycle power plants (GTCCPP) in Taiwan. In: Johnson D, editor. Electric power. Fourth annual conference and exhibition, vol. 4A; 2004. St Louis, MI, USA: American Center. p. 1–15. [1]], condenser pressure and power demand. In the Power Purchase Agreements (PPA) written in Taiwan, the capacity payment is based on the guaranteed power output during the operating period. Therefore, operating the CCPP at the highest performance and maintaining the guaranteed or contractual power output are important factors to get the full capacity and energy payments from the power purchaser and reduce the fuel and operating costs for the power producer.

Development of a Maintenance Program for Major Gas Turbine Hot Gas Path Parts

The thermal efficiency of gas turbine combined cycle power generation plants increase significantly in accordance with turbine inlet temperature. Gas turbine combined cycle power plants operating at high turbine inlet temperature are popular as a main thermal power station among our electric power companies in Japan. Thus, gas turbine hot gas parts are working under extreme conditions which will strongly affect their lifetime as well as maintenance costs for repaired and replaced parts. To reduce the latter is of major importance to enhance cost effectiveness of the plant. This report describes a gas turbine maintenance management program of main hot gas parts (combustor chambers, transition pieces, turbine first stage nozzles and first stage buckets) for management persons of gas turbine combined cycle power stations in order to obtain an optimal gas turbine maintenance schedule considering rotation, repair and replacement, or exchange of those parts.

Biomass cofiring: economics, policy and opportunities

The US Department of Energy (DOE), Electric Power Research Institute (EPRI) and utilities are evaluating, testing and applying technology that can give a new, and potentially profitable, mission to existing coal-fired power plants. The oldest of all fuels, wood, and the old original fuel of the industrial revolution, coal, are key to this move to a new mission. Technical issues that can lead to doubt about, or outright rejection of, wood (or biomass) cofiring are, in fact, being resolved through testing and experience. DOE, EPRI and utilities have joined to cosponsor tests in full-sized boilers and design/cost/supply studies related to these tests. Economic calculations, based on the measured performance and on cost estimates confirmed in purchases for the tests, are presented in this paper. The technical feasibility is proved. The constraints are identified. So far, the profits are in the future. Policy changes that produce stronger economic incentives could make profit possible today, and enable this low-cost form of renewable power to be deployed. But, without the policy, or market, change, the economic barrier is a strong one, when biomass cofiring must compete with low-cost coal at low fuel cost and with low-capital-cost gas turbine combined cycle power plants. The economics would not be a barrier at all if biomass cofiring were in competition against moderate-velocity wind power or solar PV power.

00/03629 Thermodynamic analysis and optimization of gas/ steam turbine combined-cycle power plants with integrated coal gasification

00/03629 Thermodynamic analysis and optimization of gas/ steam turbine combined-cycle power plants with integrated coal gasification

Startup optimization of a combined cycle power plant based on cooperative fuzzy reasoning and a neural network

A startup optimization control system for a gas and steam turbine combined cycle power plant is developed. The system can minimize startup time of the plant through cooperative fuzzy reasoning and a neural network autonomously adapting to varying process dynamics due to varying operational conditions, i.e. the ambient temperature and humidity. The operational conditions are taken into consideration by the neural network with a learning mechanism to optimize the schedule. The system is applied to a simulation for a plant with a three pressure staged reheat type 235.7 MW rated capacity, and the following points are seen. (1) The system can harmonize machines operations making good use of the operational margins, i.e. machine thermal stress and NO/sub x/ emission. (2) Startup time and energy loss are reduced by 35.6% and 26.3%, respectively, compared with the conventional off-line startup scheduling method.