Gas Turbine Combined Cycle Flexibility: A Dynamic Model for Compressor Intake Conditioning Through a Heat-Pump

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Iacopo Rossi ◽  
Luca Piantelli ◽  
Alberto Traverso

Abstract The flexibility of power plants is a critical feature in energy production environments nowadays, due to the high share of nondispatchable renewables. This fact dramatically increases the number of daily startups and load variations of power plants, pushing the current technologies to operate out of their optimal range. Furthermore, ambient conditions significantly influence the actual plant performance, creating deviations against the energy sold during the day-ahead and reducing the profit margins for the operators. A solution to reduce the impact of unpredicted ambient conditions, and to increase the flexibility margins of existing combined cycles, is represented by the possibility of dynamically controlling the temperature at compressor intake. At present, cooling down the compressor intake is a common practice to govern combined cycle performance in hot regions such as the Middle East and Africa, while heating up the compressor intake is commonly adopted to reduce the minimum environmental load (MEL). However, such applications involve relatively slow regulation of air intake, mainly coping with extreme operating conditions. The use of continuously varying, at a relatively quick pace, the air temperature at compressor intake, to mitigate ambient condition fluctuations and to cope with electrical market requirements, involves proper modeling of the combined cycle dynamic behavior, including the short-term and long-term impacts of intake air temperature variations. This work presents a dynamic modeling framework for the whole combined cycle applied to one of IREN Energia's Combined Cycle Units. The paper encloses the model validation against field data of the target power plant. The validated model is then used to show the potential in flexibility augmentation of properly adjusting the compressor intake temperature during operation.

Author(s):  
Iacopo Rossi ◽  
Luca Piantelli ◽  
Alberto Traverso

Abstract The flexibility of power plants is a critical feature in energy production environments nowadays, due to the high share of non-dispatchable renewables. This fact dramatically increases the number of daily startups and load variations of power plants, pushing the current technologies to operate out of their optimal range. Furthermore, ambient conditions significantly influence the actual plant performance, creating deviations against the energy sold during the day-ahead and reducing the profit margins for the operators. A solution to reduce the impact of unpredicted ambient conditions, and to increase the flexibility margins of existing combined cycles, is represented by the possibility of dynamically controlling the temperature at compressor intake. At present, cooling down the compressor intake is a common practice to govern combined cycle performance in hot regions such as the Middle East and Africa, while heating up the compressor intake is commonly adopted to reduce the Minimum Environmental Load (MEL). However, such applications involve relatively slow regulation of air intake, mainly coping with extreme operating conditions. The use of continuously varying, at a relatively quick pace, the air temperature at compressor intake, to mitigate ambient condition fluctuations and to cope with electrical market requirements, involves proper modeling of the combined cycle dynamic behavior, including the short-term and long-term impacts of intake air temperature variations. This work presents a dynamic modeling framework for the whole combined cycle applied to one of IREN Energia’s Combined Cycle Units. The paper encloses the model validation against field data of the target power plant. The validated model is then used to show the potential in flexibility augmentation of properly adjusting the compressor intake temperature during operation.


Author(s):  
Nicola Palestra ◽  
Giovanna Barigozzi ◽  
Antonio Perdichizzi

The paper presents the results of an investigation on inlet air cooling systems based on cool thermal storage, applied to combined cycle power plants. Such systems provide a significant increase of electric energy production in the peak hours; the charge of the cool thermal storage is performed instead during the night time. The inlet air cooling system also allows the plant to reduce power output dependence on ambient conditions. A 127MW combined cycle power plant operating in the Italian scenario is the object of this investigation. Two different technologies for cool thermal storage have been considered: ice harvester and stratified chilled water. To evaluate the performance of the combined cycle under different operating conditions, inlet cooling systems have been simulated with an in-house developed computational code. An economical analysis has been then performed. Different plant location sites have been considered, with the purpose to weigh up the influence of climatic conditions. Finally, a parametric analysis has been carried out in order to investigate how a variation of the thermal storage size affects the combined cycle performances and the investment profitability. It was found that both cool thermal storage technologies considered perform similarly in terms of gross extra production of energy. Despite this, the ice harvester shows higher parasitic load due to chillers consumptions. Warmer climates of the plant site resulted in a greater increase in the amount of operational hours than power output augmentation; investment profitability is different as well. Results of parametric analysis showed how important the size of inlet cooling storage may be for economical results.


Author(s):  
Helmer Andersen

Fuel is by far the largest expenditure for energy production for most power plants. New tools for on-line performance monitoring have been developed for reducing fuel consumption while at the same time optimizing operational performance. This paper highlights a case study where an online performance-monitoring tool was employed to continually evaluate plant performance at the Kalaeloa Combined Cycle Power Plant. Justification for investment in performance monitoring tools is presented. Additionally the influence of various loss parameters on the cycle performance is analyzed with examples. Thus, demonstrating the potential savings achieved by identifying and correcting the losses typically occurring from deficiencies in high impact component performance.


Author(s):  
S. Can Gülen ◽  
Indrajit Mazumder

Cost of electricity (COE) is the most widely used metric to quantify the cost-performance trade-off involved in comparative analysis of competing electric power generation technologies. Unfortunately, the currently accepted formulation of COE is only applicable to comparisons of power plant options with the same annual electric generation (kilowatt-hours) and the same technology as defined by reliability, availability, and operability. Such a formulation does not introduce a big error into the COE analysis when the objective is simply to compare two or more base-loaded power plants of the same technology (e.g., natural gas fired gas turbine simple or combined cycle, coal fired conventional boiler steam turbine, etc.) and the same (or nearly the same) capacity. However, comparing even the same technology class power plants, especially highly flexible advanced gas turbine combined cycle units with cyclic duties, comprising a high number of daily starts and stops in addition to emissions-compliant low-load operation to accommodate the intermittent and uncertain load regimes of renewable power generation (mainly wind and solar) requires a significant overhaul of the basic COE formula. This paper develops an expanded COE formulation by incorporating crucial power plant operability and maintainability characteristics such as reliability, unrecoverable degradation, and maintenance factors as well as emissions into the mix. The core impact of duty cycle on the plant performance is handled via effective output and efficiency utilizing basic performance correction curves. The impact of plant start and load ramps on the effective performance parameters is included. Differences in reliability and total annual energy generation are handled via energy and capacity replacement terms. The resulting expanded formula, while rigorous in development and content, is still simple enough for most feasibility study type of applications. Sample calculations clearly reveal that inclusion (or omission) of one or more of these factors in the COE evaluation, however, can dramatically swing the answer from one extreme to the other in some cases.


Author(s):  
A. D. Ramaglia ◽  
U. Ruedel ◽  
V. Stefanis ◽  
S. Florjancic

The operating conditions of the gas turbine combined cycle (GTCC) power plants have significantly changed over the last few years and are directed towards an improved operational and fuel flexibility, increased GT power output and efficiency and improved component lifetime. The purpose of this paper is to provide an overview of the development, analysis and validation of modern gas turbine features, parts and components for the AE64.3, AE94.2, AE94.3A, the GT26 and GT36. The development of compressor blades with a low uncertainty using multidisciplinary optimization techniques is outlined while the lifetime of a welded rotor is quantified using a damage-tolerant lifetime assessment method based on experimental creep data. For the lateral dynamics of the shaft train a modal-based approach supported by elastic structures will be described. For the axial flow turbine, the aerodynamic and heat transfer related design and validation of film cooled vanes and blades will be introduced with a particular focus on the tip area, the platforms and the application of under-platform dampers. Furthermore, the impact of the combustor-turbine interface on the turbine vane aerodynamics and film cooling characteristics is shown. For the continued very successful operation of the Constant Pressure Sequential Combustion System (CPSC), the thermos-acoustic activities of can combustors as well as the rig-to-engine transferability are presented. Recent approaches to the development of SLM parts for turbine hardware, specifically the approach used to select process parameters and creation of preliminary material models will also be briefly summarized.


Author(s):  
S. Can Gülen ◽  
Indrajit Mazumder

Cost of electricity (COE) is the most widely used metric to quantify the cost-performance trade-off involved in comparative analysis of competing electric power generation technologies. Unfortunately, the currently accepted formulation of COE is only applicable to comparisons of power plant options with the same annual electric generation (kilowatt-hours) and same technology as defined by reliability, availability and operability. Such a formulation does not introduce a big error into the COE analysis when the objective is simply to compare two or more baseloaded power plants of the same technology (e.g., natural gas fired gas turbine simple or combined cycle, coal fired conventional boiler steam turbine, etc.) and the same (or nearly the same) capacity. However, comparing even the same technology class power plants, especially highly flexible advanced gas turbine combined cycle units with cyclic duties, comprising a high number of daily starts and stops in addition to emissions-compliant low-load operation to accommodate the intermittent and uncertain load regimes of renewable power generation (mainly wind and solar) requires a significant overhaul of the basic COE formula. This paper develops an expanded COE formulation by incorporating crucial power plant operability and maintainability characteristics such as reliability, unrecoverable degradation, and maintenance factors as well as emissions into the mix. The core impact of duty cycle on the plant performance is handled via effective output and efficiency utilizing basic performance correction curves. The impact of plant start and load ramps on the effective performance parameters is included. Differences in reliability and total annual energy generation are handled via energy and capacity replacement terms. The resulting expanded formula, while rigorous in development and content, is still simple enough for most feasibility study type of applications. Sample calculations clearly reveal that inclusion (or omission) of one or more of these factors in the COE evaluation, however, can dramatically swing the answer from one extreme to the other in some cases.


Author(s):  
Pablo Andrés Silva Ortiz ◽  
Osvaldo José Venturini ◽  
Electo Eduardo Silva Lora

The increasing trend in global production of petroleum coke (petcoke) is the result of their multiple and innovative industrial applications. From this point of view and also considering the current situation of the traditional energy reserves worldwide, it is important to conduct studies in this area through analysis of the main components of the power plants utilizing this fuel (petcoke). The main target of this study is to realize a techno-economic evaluation of IGCC (Integrated Gasification Combined Cycle) technology, using Brazilian coal, petcoke and a mix of 50% coal and 50% petcoke as fuel. In this paper, the gasification process and the combined cycle are analyzed, considering the implementation of the IGCC technology in the Termobahia power plant. Termobahia is a cogeneration combined cycle power plant, located in the Brazilian state of Bahia that produces 190 MW of electricity and 350 ton/h of steam. The steam produced is sold to an oil refinery (RLAM) located next to it. In first part of this work, the production of the synthesis gas (syngas) from coal gasification was simulated using CeSFaMBi™ software. In the next part, the syngas produced is used to analyze the power plant performance through GateCycle™ software. Finally, the obtained operational and economic parameters are compared with the actual operational parameters of the Termobahia power plant in terms of costs, fuel substitution and combined cycle performance variables, as net power, global efficiency and heat rate.


2020 ◽  
Vol 12 (8) ◽  
pp. 3330
Author(s):  
Guido Marseglia ◽  
Blanca Fernandez Vasquez-Pena ◽  
Carlo Maria Medaglia ◽  
Ricardo Chacartegui

The Sustainable Development Goals 2030 Agenda of United Nations raises the need of clean and affordable energy. In the pathway for more efficient and environmentally friendly solutions, new alternative power technologies and energy sources are developed. Among these, the use of syngas fuels for electricity generation can be a viable alternative in areas with high biomass or coal availability. This paper presents the energy, environmental and economic analyses of a modern combined cycle plant with the aim to evaluate the potential for a combined power plant running with alternative fuels. The goal is to identify the optimal design in terms of operating conditions and its environmental impact. Two possible configurations are investigated in the power plant presented: with the possibility to export or not export steam. An economic analysis is proposed to assess the plant feasibility. The effect of the different components in its performance is assessed. The impact of using four different syngases as fuel is evaluated and compared with the natural gas fuelled power cycle. The results show that a better efficiency is obtained for the syngas 1 (up to 54%), in respect to the others. Concerning pollutant emissions, the syngas with a GHG impact and lower carbon dioxide (CO2) percentage is syngas 2.


Author(s):  
Hugh Jin ◽  
Terrence B. Sullivan ◽  
Jeffrey R. Friedman

Gas turbines in combined cycle (CC) power plants, in phased construction situations, usually operate for several months in the simple cycle (SC) mode while the steam portion of the plant is being constructed. At the time of commissioning the combined cycle phase, the gas turbines typically have accumulated a considerable number of operating hours and have possibly experienced some degradation, especially on turbines that have run on dual fuels. To determine the combined cycle new and clean performance, it is necessary to employ a phased testing approach. The phased testing approach involves testing the gas turbines when they are in new and clean condition and combining those results with the measured new and clean steam turbine cycle performance. The method of the phased testing has been introduced in ASME PTC 46 (1996) “Performance Test Code on Overall Plant Performance”. This paper will discuss in detail the test protocol, fundamental equations, corrections, and uncertainty analysis of phased testing. This paper will also discuss performance degradation and engine setting changes between the phases.


Author(s):  
Nicola Palestra ◽  
Giovanna Barigozzi ◽  
Antonio Perdichizzi

The paper presents the results of an investigation on inlet air cooling systems based on cool thermal storage, applied to combined cycle power plants. Such systems provide a significant increase of electric energy production in the peak hours; the charge of the cool thermal storage is performed instead during night time. The inlet air cooling system also allows the plant to reduce power output dependence on ambient conditions. A 127 MW combined cycle power plant operating in the Italian scenario is the object of this investigation. Two different technologies for cool thermal storage have been considered: ice harvester and stratified chilled water. To evaluate the performance of the combined cycle under different operating conditions, inlet cooling systems have been simulated with an in-house developed computational code. An economical analysis has been then performed. Different plant location sites have been considered, with the purpose to weigh up the influence of climatic conditions. Finally, a parametric analysis has been carried out in order to investigate how a variation of the thermal storage size affects the combined cycle performances and the investment profitability. It was found that both considered cool thermal storage technologies perform similarly in terms of gross extra-production of energy. Despite to that, ice harvester shows higher parasitic load due to chillers consumptions. Warmer climates of plant site resulted to increase more the amount of operational hours than power output augmentation; investment profitability is different as well. Results of parametric analysis showed how important may be, for economical results, the size of inlet cooling storage.


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