Exergy Analysis of a Simple Gas Turbine System Considering Combustion Process as Complete Combustion and Equilibrium Combustion

2010 ◽  
Author(s):  
Nayyer Razmara ◽  
Rahim Khoshbakhti Saray
Keyword(s):  
Gas Turbine ◽  
Exergy Analysis ◽  
Combustion Process ◽  
Combustion Products ◽  
Combustion Model ◽  
Exergy Destruction ◽  
Complete Combustion ◽  
Combustion Models ◽  
Chemical Exergy ◽  
Chemical Availability

Exergy analysis provides useful information for the system optimization. An exergy analysis identifies the sources of thermodynamic inefficiencies by evaluating the exergy destruction within each system component. The present work is an attempt to compare the effect of variations of species concentrations of the combustion process in a simple gas turbine system. Therefore, using a Complete combustion model and an Equilibrium combustion program model, the exergetic evaluation is carried out for a simple gas turbine system with a rated output power of 30 MW. The Complete combustion involves O2, N2, CO2, H2O and Equilibrium combustion model involves N2, O2, CO2, H2O, CO, H2, H, O, OH, N, NO as the species of combustion products. In this work, Equilibrium combustion products were calculated using Olikara and Borman method. Also, a principle of division of chemical availability (exergy) into oxidation availability, reduction availability and diffusion availability has been investigated in these models. Expression involving the variables for exergetic efficiency, exergy destruction, and chemical availability in the components of the gas turbine cycle are derived. The exergy losses and efficiencies of components based on both Complete combustion and Equilibrium combustion models are evaluated. The exergetic efficiencies of the plant based on Complete combustion and Equilibrium combustion are determined to be 28.11% and 28.16%, respectively. It is found that, variation of species has negligible effect on the system main parameters. It is also concluded that chemical exergy in Equilibrium combustion is a little more than that of Complete combustion. Because of additional species involved in Equilibrium combustion, reduction availability and oxidation availability are defined in this modeling beside diffusion availability and it increases chemical exergy of equilibrium combustion modeling. The results obtained here show that in the analysis of the power plant cycles, a simple combustion model (i.e. Complete combustion model) is in good agreement with a complex combustion model considering various species (i.e. Equilibrium combustion model). As a result, there is negligible difference between results of the mentioned combustion models and the simple Complete combustion model facilitates the analysis of such processes.

Enhancement of Simple Gas Turbine System and Cogeneration Power Plant Using Dual Fueling of Combustion Chamber: Based on Endogenous and Exogenous Exergy Destruction Concepts

2010 ◽  
Author(s):  
Nayyer Razmara ◽  
Rahim Khoshbakhti Saray
Keyword(s):  
Power Plant ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Exergy Analysis ◽  
Combustion Process ◽  
System Optimization ◽  
General Concept ◽  
System Component ◽  
Exergy Destruction ◽  
Dual Fueling

Exergy analysis provides useful information about the system optimization. An exergy analysis identifies the sources of thermodynamic inefficiencies by evaluating the exergy destruction within each system component. Splitting the exergy destruction into endogenous/exogenous parts represents a new development in the exergy analysis of energy conversion systems. The present work is an attempt to investigate the combustion process in a simple gas turbine and a cogeneration power plant based on the general concept of endogenous and exogenous exergy destruction. Therefore, using a graphical approach, the advanced exergy analysis is applied to both cycles with different fuels such as methane and diesel. Also, dual-fueling of combustion chamber is investigated based on the aforementioned approach in which 90% substitution of methane fuel for diesel one is considered. It is found that, in both cycles the combustion chamber has the largest value of the endogenous exergy destruction. The exergetic efficiency of combustion chamber increases when methane fuel is substituted for diesel fuel. Therefore, cycles efficiencies have been enhanced when fuel is substituted for diesel one. The results obtained here may provide some useful information for the optimal design and performance improvement of these cycles.

Prediction of Pressure Rise in a Gas Turbine Exhaust Duct Under Flameout Scenarios While Operating On Hydrogen and Natural Gas Blends

2021 ◽  
Author(s):  
Orlando Ugarte ◽  
Suresh Menon ◽  
Wayne Rattigan ◽  
Paul Winstanley ◽  
Priyank Saxena ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Combustion Process ◽  
Pressure Rise ◽  
Combustion Model ◽  
Computational Domain ◽  
Cfd Model ◽  
Exhaust Duct ◽  
Gas Turbine Exhaust ◽  
Turbine Exhaust

Abstract In recent years, there is a growing interest in blending hydrogen with natural gas fuels to produce low carbon electricity. It is important to evaluate the safety of gas turbine packages under these conditions, such as late-light off and flameout scenarios. However, the assessment of the safety risks by performing experiments in full-scale exhaust ducts is a very expensive and, potentially, risky endeavor. Computational simulations using a high fidelity CFD model provide a cost-effective way of assessing the safety risk. In this study, a computational model is implemented to perform three dimensional, compressible and unsteady simulations of reacting flows in a gas turbine exhaust duct. Computational results were validated against data obtained at the simulated conditions in a representative geometry. Due to the enormous size of the geometry, special attention was given to the discretization of the computational domain and the combustion model. Results show that CFD model predicts main features of the pressure rise driven by the combustion process. The peak pressures obtained computationally and experimentally differed in 20%. This difference increased up to 45% by reducing the preheated inflow conditions. The effects of rig geometry and flow conditions on the accuracy of the CFD model are discussed.

Exergy Analysis of Part Flow Evaporative Gas Turbine Cycles: Part 2 — Results and Discussion

2002 ◽  
Author(s):  
Maria Jonsson ◽  
Jinyue Yan
Keyword(s):  
Gas Turbine ◽  
Heat Recovery ◽  
Exergy Analysis ◽  
Compressed Air ◽  
Cycle Performance ◽  
Exergy Destruction ◽  
Exergetic Efficiency ◽  
Recovery System ◽  
Heat Recovery System ◽  
Flow Case

This paper is the second part of a two-part paper. The first part contains an introduction to the evaporative gas turbine (EvGT) cycle and the methods used in the study. The second part contains the results, discussion, and conclusions. In this study, exergy analysis of EvGT cycles with part flow humidification based on the industrial GTX100 and the aeroderivative Trent has been performed. In part flow EvGT cycles, only a fraction of the compressed air is passed through the humidification system. The paper presents and analyzes the exergetic efficiencies of the components of both gas turbine cycles. The highest cycle exergetic efficiencies were found for the full flow case for the GTX100 cycles and for the 20% part flow case for the Trent cycles. The largest exergy destruction occurs in the combustor, and the exergetic efficiency of this component has a large influence on the overall cycle performance. The exergy destruction of the heat recovery system is low.

Development of a Partial Oxidation Gas Turbine (POGT) for Innovative Gas Turbine Systems

2007 ◽  
Author(s):  
Joseph Rabovitser ◽  
Serguei Nester ◽  
Stan Wohadlo ◽  
Kenneth Smith ◽  
Waseem Nazeer ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Partial Oxidation ◽  
Combustion Engine ◽  
Combustion Products ◽  
Operating Conditions ◽  
Working Fluid ◽  
Single Digit ◽  
Complete Combustion ◽  
Secondary Fuel ◽  
Oxidation Reactor

Gas Technology Institute (GTI) has been advancing the POGT concept since 1995. The progress to date of a GTI-led team on the development and testing of a POGT prototype, and POGT-based systems are presented. There are two main features that distinguish a POGT from a conventional gas turbine: the design arrangement and the thermodynamic processes used in operation. One unique feature is utilization of a non-catalytic partial oxidation reactor (POR) in place of a typical combustor. An important secondary distinction is that a much smaller compressor is required, one that typically supplies less than half of the air flow required in a conventional gas turbine. From a thermodynamic point of view, the working fluid provided by the POR (a secondary fuel gas) has much higher specific heat than complete combustion products. This allows higher energy per unit mass of fluid to be extracted by the POGT expander than is the conventional case. A POR operates at fuel rich conditions, typically at equivalence ratios on the order of 2.5, and virtually any hydrocarbon fuel can be combusted. Because of these fuel rich conditions, incomplete combustion products are used as the hot section working fluid. A POGT thus produces two products: power and a secondary fuel that usually is a H2 rich gas. This characteristic can lead to high efficiencies and ultra-low emissions (single digit NOx and CO levels) when the secondary fuel is burned cleanly in a bottoming cycle. When compared to the equivalent standard gas turbine bottoming cycle combination, the POGT provides an increase of about 10 percentage points in overall system efficiency. Two areas of recent development are addressed in the paper: POGT development and experimental evaluation of a 7 MWth pressurized non-catalytic POR installed at GTI; and examples of POGT-based systems for combined generation of power, heat, syngas, hydrogen, etc. The POGT design approach to convert an existing engine into a POGT by replacing its combustor with a POR together with concomitant modifications of other engine components is discussed. Experimental results of the POR operation include descriptions of major operating conditions: start up, light off conditions, lean combustion mode, lean-to-rich transition, and operation in rich partial oxidation mode at different loads and air to fuel ratios. The overall efficiency of a POGT two-stage power system is typically high and can approach 70% depending on the POGT operating conditions and the chosen bottoming cycle. The bottoming-cycle can be either a low pressure (or vacuum) combustion turbine, or an internal combustion engine, or a solid oxide fuel cell, or any combination of them. In addition, the POGT can be used as the driver for cogeneration systems. In such cogeneration systems the bottoming cycle can be a fuel-fired boiler, an absorption chiller, or an industrial furnace. The POGT is ideally suited for the co-production of power and either hydrogen, or synthesis gas (syngas), or chemicals. Some of these important applications are discussed.

Comparative Energy and Exergy Analysis of Proposed Gas Turbine Cycle With Simple Gas Turbine Cycle at Same Operational Cost

2019 ◽  
Author(s):  
M. N. Khan ◽  
Ibrahim M. Alarifi ◽  
I. Tlili
Keyword(s):  
Gas Turbine ◽  
Fuel Consumption ◽  
Exergy Analysis ◽  
Pressure Ratio ◽  
Specific Fuel Consumption ◽  
Exergy Destruction ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Gas Turbine Cycle ◽  
The Impact

Abstract Environmentally friendly and effective power systems have been receiving increased investigation due to the aim of addressing global warming, energy expansion, and economic growth. Gas turbine cycles are perceived as a useful technology that has advanced power capacity. In this research, a gas turbine cycle has been proposed and developed from a simple and regenerative gas turbine cycle to enhance performance and reduce Specific fuel consumption. The impact of specific factors regarding the proposed gas turbine cycle on thermal efficiency, net output, specific fuel consumption, and exergy destruction, have been inspected. The assessments of the pertinent parameters were performed based on conventional thermodynamic energy and exergy analysis. The results obtained indicate that the peak temperature of the Proposed Gas Turbine Cycle increased considerably without affecting fuel consumption. The results show that at Pressure Ratio (rp = 6) the performance of the Proposed Gas Turbine Cycle is much better than Single Gas Turbine Cycle but the total exergy destruction of Proposed Gas Turbine Cycle higher than the SGTC.

scholarly journals Exergy Efficiency Optimization for Gas Turbine Based Cogeneration Systems

2013 ◽  
Author(s):  
Ana C. Ferreira ◽  
Senhorinha F. Teixeira ◽  
José C. Teixeira ◽  
Manuel L. Nunes ◽  
Luís B. Martins
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Exergy Analysis ◽  
Exergy Efficiency ◽  
Plant Performance ◽  
System Component ◽  
Inlet Temperature ◽  
Exergy Destruction ◽  
Turbine Inlet Temperature ◽  
Turbine Inlet

Energy degradation can be calculated by the quantification of entropy and loss of work and is a common approach in power plant performance analysis. Information about the location, amount and sources of system deficiencies are determined by the exergy analysis, which quantifies the exergy destruction. Micro-gas turbines are prime movers that are ideally suited for cogeneration applications due to their flexibility in providing stable and reliable power. This paper presents an exergy analysis by means of a numerical simulation of a regenerative micro-gas turbine for cogeneration applications. The main objective is to study the best configuration of each system component, considering the minimization of the system irreversibilities. Each component of the system was evaluated considering the quantitative exergy balance. Subsequently the optimization procedure was applied to the mathematical model that describes the full system. The rate of irreversibility, efficiency and flaws are highlighted for each system component and for the whole system. The effect of turbine inlet temperature change on plant exergy destruction was also evaluated. The results disclose that considerable exergy destruction occurs in the combustion chamber. Also, it was revealed that the exergy efficiency is expressively dependent on the changes of the turbine inlet temperature and increases with the latter.

Exergy Analysis of Integration Between Air Separation Process and IGCC

2000 ◽  
Author(s):  
Zelong Liu ◽  
Hongguang Jin ◽  
Rumou Lin
Keyword(s):  
Gas Turbine ◽  
Exergy Analysis ◽  
Combined Cycle ◽  
Air Separation ◽  
Exergy Destruction ◽  
Steam Generation ◽  
Separation Unit ◽  
Air Compressor ◽  
Nitrogen Injection ◽  
Air Separation Unit

Abstract Integrated Gasification Combined Cycle (IGCC) is considered as one of the advanced clean coal power technologies. Here, we have investigated an IGCC with air separation unit (ASU) on the basis of exergy analysis, and clarified the distribution of exergy destruction in sub-systems including air separation unit, coal gasifier, coal gas clean-up unit, air compressor, combustor of gas turbine, gas turbine, heat recovery steam generation and steam turbine. Particularly, we have focused on the interaction between the ASU and the gas turbine (GT). The results obtained disclosed the significant role of the integration between air separation unit and air compressor in the GT, and the effect of nitrogen injection to the combustor on IGCC overall performance. The study also points out that larger exergy destruction take place in the processes of gasification, combustion in GT, and air separation, and so does the change of exergy destruction distribution with the air integration degree and the nitrogen injection ratio. We have demonstrated the potential for improving the IGCC system. This investigation will be valuable for the synthesis of next-generation IGCC.

Prediction of Pressure Rise in a Gas Turbine Exhaust Duct Under Flameout Scenarios While Operating on Hydrogen and Natural Gas Blends

2021 ◽  
Author(s):  
Orlando Ugarte ◽  
Suresh Menon ◽  
Wayne Rattigan ◽  
Paul Winstanley ◽  
Priyank Saxena ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Combustion Process ◽  
Pressure Rise ◽  
Combustion Model ◽  
Computational Domain ◽  
Cfd Model ◽  
Exhaust Duct ◽  
Gas Turbine Exhaust ◽  
Turbine Exhaust

Abstract In recent years, there is a growing interest in blending hydrogen with natural gas fuels to produce low carbon electricity. It is important to evaluate the safety of gas turbine packages under these conditions, such as late-light off and flameout scenarios. However, the assessment of the safety risks by performing experiments in full-scale exhaust ducts is a very expensive and, potentially, risky endeavor. Computational simulations using a high fidelity CFD model provide a cost-effective way of assessing the safety risk. In this study, a computational model is implemented to perform three dimensional, compressible and unsteady simulations of reacting flows in a gas turbine exhaust duct. Computational results were validated against data obtained at the simulated conditions in a representative geometry. Due to the enormous size of the geometry, special attention was given to the discretization of the computational domain and the combustion model. Results show that CFD model predicts main features of the pressure rise driven by the combustion process. The peak pressures obtained computationally and experimentally differed in 20%. This difference increased up to 45% by reducing the preheated inflow conditions. The effects of rig geometry and flow conditions on the accuracy of the CFD model are discussed.

Advanced Exergy Analysis of the Supercritical Carbon Dioxide Power Cycle for Waste Heat Recovery of Gas Turbine

2021 ◽  
Author(s):  
Bo Li ◽  
Shun-sen Wang ◽  
Liming Song
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Gas Turbine ◽  
Exergy Analysis ◽  
Waste Heat ◽  
Design Stage ◽  
Exergy Destruction ◽  
Technical Improvement ◽  
Power Cycle ◽  
Supercritical Carbon

Abstract In this paper, the supercritical carbon dioxide power cycle used to recover the waste heat of gas turbine is investigated by means of conventional exergy analysis and advanced exergy analysis. Firstly, the thermodynamic parameters of carbon dioxide cycle in design stage are determined by single-objective optimization with net power output as objective function. Then, conventional exergy analysis is carried out on the partial heating cycle under real, unavoidable and ideal conditions. After that, advanced exergy analysis, in which the exergy destruction is divided into endogenous / exogenous part and avoidable / unavoidable part is adopted to reveal the improvement potential of the system and illustrate the interaction among the components. According to the calculation results, a total amount of 3.55MW (47.33%) exergy destruction could be reduced by the improvement of component efficiency. Endogenous exergy destruction is higher than exogenous exergy destruction in all components. Based on the results of conventional exergy analysis, the high-temperature heater should be paid attention in order to reduce exergy destruction. However, according to the results of advanced exergy analysis, the technical improvement of turbine should be emphasized due to its high endogenous-avoidable exergy destruction. Meanwhile, for the components with high unavoidable exergy destruction, external systems should be employed to exploit the underutilized energy and enhance the system performance.

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