scholarly journals Thermal Efficiency Projections of a Simple-Cycle Gas Turbine in Biogas Power Generation

1996 ◽  
Author(s):  
David E. Yomogida ◽  
Ngo D. Thinh ◽  
Valentino M. Tiangco ◽  
Ying Lee
Keyword(s):  
Power Generation ◽  
Sensitivity Analysis ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Design Parameter ◽  
Computer Code ◽  
Simple Cycle ◽  
Specific Work ◽  
Expected Values

The thermal efficiency of a 125 kW simple-cycle gas turbine for biogas power generation was estimated, using a computer code developed for simple-cycle gas turbines. The computer code can predict expected values for the thermal efficiency and specific work along with the expected temperatures and pressures at various stages in the gas turbine. For the 125 kW Solar Gas Turbine (Titan series), the projected thermal efficiency is about 14%. This paper additionally presents a sensitivity analysis oo the operating condition and design parameter which had the greatest impacts on the thermal efficiency. These results will assist the California Energy Commission in determining the type of combustion device most suitable for biogas power generation.

Systems Level Performance Estimations for a Pulse Detonation Combustor Based Hybrid Engine

2008 ◽  
Author(s):  
Venkat E. Tangirala ◽  
Narendra D. Joshi
Keyword(s):  
Gas Turbine ◽  
Compression Ratio ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Entire Range ◽  
Operating Conditions ◽  
Simple Cycle ◽  
Inlet Temperature ◽  
Specific Work ◽  
Pulse Detonation

The Pulse Detonation Combustor (PDC) has recently evoked much interest as a pressure-gain combustor for use in gas turbines. A key application for a Pulse Detonation Engine (PDE) concept has been envisioned as a hybrid power generation engine, which would replace the combustor in a conventional gas turbine with a PDC. Estimations of performance parameters, namely, thermal efficiency (ηth) and specific work (Wnet) are reported for a PDC based hybrid engine for various configurations of the engine. The performance enhancing configurations of the PDC-based hybrid engine, considered in the present study, include simple cycle, intercooling, regeneration and reheat, similar to the configurations for a conventional gas turbine (GT) engine in the literature. The performance estimations for a conventional gas turbine engine and a PDC based hybrid engine are compared for the same operating conditions (such as inlet pressure, inlet temperature, compression ratio, overall equivalence ratio) and for various configurations. The thermal efficiency of an intercooled PDC hybrid engine with regeneration has the highest value for the entire range of turbine pressure ratios, from 1.2 to 40 (corresponding to a compression ratio range of 1 to 30). An intercooled PDC based hybrid engine with reheat produces the highest specific work (Wnet) when compared to all other configurations. Among simple-cycle /regeneration /reheat configurations of a PDC based hybrid engine, ητh for the intercooled PDC based hybrid engines has the highest estimated value (0.47) at a turbine pressure ratio of 30. The intercooled PDC based hybrid engine also produces the highest specific work (Wnet) when compared to simple-cycle/regeneration/reheat hybrid engine configurations over the entire range of turbine pressure ratios.

Advanced Gas Turbine and High Performance Gas-Steam Combined Cycle Plant With Blade Cooling Air Controlling

2006 ◽  
Author(s):  
Tadashi Tsuji
Keyword(s):  
Power Generation ◽  
Heat Exchanger ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Combined Cycle ◽  
Hot Water ◽  
Blade Cooling ◽  
Combined Cycle Plant ◽  
Cooling Air

Air cooling blades are usually applied to gas turbines as a basic specification. This blade cooling air is almost 20% of compressor suction air and it means that a great deal of compression load is not converted effectively to turbine power generation. This paper proposes the CCM (Cascade Cooling Module) system of turbine blade air line and the consequent improvement of power generation, which is achieved by the reduction of cooling air consumption with effective use of recovered heat. With this technology, current gas turbines (TIT: turbine inlet temperature: 1350°C) can be up-rated to have a relative high efficiency increase. The increase ratio has a potential to be equivalent to that of 1500°C Class GT/CC against 1350°C Class. The CCM system is designed to enable the reduction of blade cooling air consumption by the low air temperature of 15°C instead of the usual 200–400°C. It causes the turbine operating air to increase at the constant suction air condition, which results in the enhancement of power and thermal efficiency. The CCM is installed in the cooling air line and is composed of three stage coolers: steam generator/fuel preheater stage, heat exchanger stage for hot water supplying and cooler stage with chilled water. The coolant (chilled water) for downstream cooler is produced by an absorption refrigerator operated by the hot water of the upstream heat exchanger. The proposed CCM system requires the modification of cooling air flow network in the gas turbine but produces the direct effect on performance enhancement. When the CCM system is applied to a 700MW Class CC (Combined Cycle) plant (GT TIT: 135°C Class), it is expected that there will be a 40–80MW increase in power and +2–5% relative increase in thermal efficiency.

One-Dimensional Model to Quantify NOx Reduction in Gas Turbines Using EGR

1998 ◽  
Author(s):  
K. K. Botros ◽  
M. J. de Boer ◽  
G. Kibrya
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Nox Reduction ◽  
Simulation Software ◽  
Specific Work ◽  
Dimensional Model ◽  
Nox Formation ◽  
One Dimensional ◽  
Thermal Nox

A one dimensional model based on fundamental principles of gas turbine thermodynamics and combustion processes was constructed to quantify the principle of exhaust gas recirculation (EGR) for NOx reduction. The model utilizes the commercial process simulation software ASPEN PLUS®. Employing a set of 8 reactions including the Zeldovich mechanism, the model predicted thermal NOx formation as function of amount of recirculation and the degree of recirculate cooling. Results show that addition of sufficient quantities of uncooled recirculate to the inlet air (i.e. EGR>∼4%) could significantly decrease NOx emissions but at a cost of lower thermal efficiency and specific work. Cooling the recirculate also reduced NOx at lower quantities of recirculation. This has also the benefit of decreasing losses in the thermal efficiency and in the specific work output. Comparison of a ‘rubber’ and ‘non-rubber’ gas turbine confirmed that residence time is one important factor in NOx formation.

Analysis of a Basic Chemically Recuperated Gas Turbine Power Plant

1994 ◽  
Vol 116 (2) ◽  
pp. 277-284 ◽  
Author(s):  
K. F. Kesser ◽  
M. A. Hoffman ◽  
J. W. Baughn
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Waste Heat ◽  
Computer Code ◽  
Combined Cycle ◽  
Specific Work ◽  
Turbine Cooling ◽  
Specific Heats ◽  
Methane Steam ◽  
Cooling Air

This paper investigates a “basic” Chemically Recuperated Gas Turbine (a “basic” CRGT is defined here to be one without intercooling or reheat). The CRGT is of interest due to its potential for ultralow NOx emissions. A computer code has been developed to evaluate the performance characteristics (thermal efficiency and specific work) of the Basic CRGT, and to compare it to the steam-injected gas turbine (STIG), the combined cycle (CC) and the simple cycle gas turbine (SC) using consistent assumptions. The CRGT model includes a methane-steam reformer (MSR), which converts a methane-steam mixture into a hydrogen-rich fuel using the “waste” heat in the turbine exhaust. Models for the effects of turbine cooling air, variable specific heats, and the real gas effects of steam are included. The calculated results show that the Basic CRGT has a thermal efficiency higher than the STIG and simple cycles but not quite as high as the combined cycle.

Thermodynamic Optimization of Reheat Gas Turbine Cycles Combined With Bottoming Cycles

2000 ◽  
Author(s):  
Isaac Shnaid
Keyword(s):  
Heat Exchange ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Arbitrary Number ◽  
Combined Cycle ◽  
Simple Cycle ◽  
Specific Work ◽  
Thermodynamic Optimization ◽  
Thermodynamic Conditions ◽  
Parametric Analyses

In this work, thermodynamic optimization of reheat gas turbine cycles (without intercooling and recuperative heat exchange) combined with bottoming cycles, is done. Thermodynamic conditions ensuring the combined cycle engine maximal specific work and thermal efficiency are formulated for a general case of arbitrary number of reheat stages with different inlet gas temperatures and isentropic efficiencies. Parametric analyses show that application of reheat cycles brings significant improvement of gas turbine and combined cycle specific work and efficiency in comparison with a case of a simple cycle gas turbine.

Cycle Optimization and High Performance Analysis of Gas Engine-Gas Turbine Combined Cycles

2005 ◽  
Author(s):  
Tadashi Tsuji
Keyword(s):  
Power Generation ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Combined Cycle ◽  
Compound System ◽  
Generation Efficiency ◽  
Engine Exhaust ◽  
Gas Engine ◽  
Exhaust Temperature

The reciprocating engine operates with a maximum pressure and temperature in its cylinders that is higher than that in conventional gas turbines. When a gas engine is integrated with a gas turbine instead of a turbocharger, it is an ETCS (Engine-Turbo Compound System). We have developed the concept of a compound system with ERGT (Engine Reheat Gas Turbine) and propose it as a system with potentially high thermal efficiency. A natural gas firing gas turbine combined cycle (CC) is selected as the standard system for a thermal power plant. A higher TIT (Turbine Inlet Temperature) of gas turbine usually enables higher power generation efficiency. Focusing on the effect of engine exhaust temperature, we found that the ETCS cycle with a ERGT has the potential to achieve higher thermal efficiency than that of a gas turbine combined cycle, with no change in TIT. An engine exhaust temperature of 1173K increases the system power generation efficiency from 46 to 50%LHV (TIT 1150°C) and 54 to 57%LHV (TIT 1350°C), respectively. The gas engine–gas turbine combined cycle has the potential to achieve a significant efficiency increase of +4.1%LHV (TIT 1150°C) and +2.8%LHV (TIT 1350°C), making it a promising system for future power plants. Efficiency is expected to be improved by +8.7% (TIT 1150°C) and +5.6% (TIT 1350°C), relatively.

The “Axi-Fuge”—A Novel Compressor

1986 ◽  
Vol 108 (2) ◽  
pp. 240-243
Author(s):  
J. O. Wiggins
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Heat Exchangers ◽  
Gas Turbines ◽  
Simple Cycle ◽  
Test Results ◽  
Marine Application ◽  
Percent Improvement ◽  
Caterpillar Tractor ◽  
The Subject

Modifying a simple-cycle gas turbine to include heat exchangers can improve its thermal efficiency significantly (as much as 20 percent). Advanced regenerative and intercooled regenerative gas turbines for marine application have recently been the subject of numerous studies, most of which have shown that lower fuel consumption can be achieved by adding heat exchangers to existing simple-cycle gas turbines. Additional improvements in thermal efficiency are available by increasing the efficiency of the turbomachinery itself, particularly that of the gas turbine’s air compressor. Studies by Caterpillar Tractor Company and Solar Turbines Incorporated on a recuperated, variable-geometry gas turbine indicate an additional 8 to 10 percent improvement in thermal efficiency is possible when an improved higher efficiency compressor is included in the gas turbine modification. During these studies a novel compressor, the Axi-Fuge, was devised. This paper discusses the Axi-Fuge concept, its origin, design criteria and approach, and some test results.

Model-Based Thermodynamic Analysis of a Hydrogen-Fired Gas Turbine with External Exhaust Gas Recirculation

2021 ◽  
Author(s):  
Thomas Bexten ◽  
Sophia Jörg ◽  
Nils Petersen ◽  
Manfred Wirsum ◽  
Pei Liu ◽  
...  
Keyword(s):  
Power Generation ◽  
Natural Gas ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Carbon Capture ◽  
Exhaust Gas ◽  
Model Based ◽  
Renewable Power ◽  
Renewable Power Generation

Abstract Climate science shows that the limitation of global warming requires a rapid transition towards net-zero emissions of greenhouse gases (GHG) on a global scale. Expanding renewable power generation is seen as an imperative measure within this transition. To compensate for the inherent volatility of renewable power generation, flexible and dispatchable power generation technologies such as gas turbines are required. If operated with CO2-neutral hydrogen or in combination with carbon capture plants, a GHG-neutral gas turbine operation could be achieved. An effective leverage to enhance carbon capture efficiency and a possible measure to safely burn hydrogen in gas turbines is the partial external recirculation of exhaust gas. By means of a model-based analysis of a gas turbine, the present study initially assesses the thermodynamic impact caused by a fuel switch from natural gas to hydrogen. Although positive trends such as increasing net electrical power output and thermal efficiency can be observed, the overall effect on the gas turbine process is only minor. In a following step, the partial external recirculation of exhaust gas is evaluated and compared both for the combustion of natural gas and hydrogen, regardless of potential combustor design challenges. The influence of altering working fluid properties throughout the whole gas turbine process is thermodynamically evaluated for ambient temperature recirculation and recirculation at an elevated temperature. A reduction in thermal efficiency can be observed as well as non-negligible changes of relevant process variables. These changes are more distinctive at a higher recirculation temperature

Sensitivity Analysis of a SOFC-GT Based Power Cycle

2008 ◽  
Author(s):  
Farshid Zabihian ◽  
Alan S. Fung ◽  
Murat Koksal ◽  
Shakil Malek ◽  
Moftah Elhebshi
Keyword(s):  
Sensitivity Analysis ◽  
Natural Gas ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Macro Level ◽  
Specific Work ◽  
Utilization Factor ◽  
Turbine Efficiency ◽  
Ohmic Losses ◽  
Mathematical Expressions

This paper presents the sensitivity analysis of tubular Solid Oxide Fuel Cell (SOFC) stacks. The macro level modelling implemented in AspenPlus™ for the simulation of hybrid SOFC-gas turbine systems. The macro level thermodynamic first law analysis was previously performed on the same model. This sensitivity analysis is the continuation towards investigating the effects of different fuel compositions and turbine and compressor efficiencies on cycle efficiency and other parameters. The model is 0-dimensional, can accept hydrocarbon fuels with user inputs of current density, fuel and air composition, flow rates, temperature, pressure and fuel utilization factor. The model outputs the composition of the exhaust, work produced, heat available for reformer, etc. The model was developed considering the activation, concentration and ohmic losses within SOFC and mathematical expressions for these were chosen based on available studies in recent literatures. In this paper different fuels such as reformed natural gas, biogas with different compositions are considered to investigate the effect of fuel composition on the performance of the hybrid SOFC-gas turbine systems. In order to monitor the performance of the system parameters such as thermal efficiency, cycle specific work, SOFC specific work, gas turbine specific work, and work ratio (SOFC work / gas turbine work) are investigated. Furthermore, for specific fuel the effect of turbine and compressor efficiencies on system’s overall performance are studied for entire range from 50% to 100%, keeping gas turbine efficiency constant and increasing compressor efficiency by 5% and vice versa. For instance, if the fuel is switched from natural gas (with 100% CH4) to biogas (with the composition of 70% CH4, 25% CO2 and 5% H2) and the other parameters are kept constant (isentropic efficiency 85% for both turbine and compressor) the overall thermal efficiency will decrease by 1.4%, whereas the cycle specific work will increase by 36.7%. In addition, the work ratio will increase by 25.1% showing that more power is generated in SOFC in comparison to gas turbine. In addition, if the efficiency of turbine and compressor increase from 85% to 90%, the efficiency and cycle specific work of the system will increase by 3.1% and 3%, respectively whereas, the work ratio will decrease by 5.6%, due to the more power generated in gas turbine.

The “Axi-Fuge”—A Novel Compressor

1986 ◽  
Author(s):  
Jesse O. Wiggins
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Heat Exchangers ◽  
Gas Turbines ◽  
Simple Cycle ◽  
Design Criteria ◽  
Variable Geometry ◽  
Test Results ◽  
Marine Application ◽  
Caterpillar Tractor

Modifying a simple-cycle gas turbine to include heat exchangers can improve its thermal efficiency significantly (as much as 20%). Advanced regenerative and intercooled regenerative gas turbines for marine application have recently been the subjects of numerous studies, most of which have shown that lower fuel comsumption can be achieved by adding heat exchangers to existing simple-cycle gas turbines. Additional improvements in thermal efficiency are available by increasing the efficiency of the turbomachinery itself, particularly that of the gas turbine’s air compressor. Studies by Caterpillar Tractor Company and Solar Turbines Incorporated on a recuperated, variable-geometry gas turbine indicate an additional 8 to 10% improvement in thermal efficiency is possible when an improved higher efficiency compressor is included in the gas turbine modification. During these studies a novel (Axi-Fuge) compressor was devised. This paper discusses the Axi-Fuge concept, its origin, design criteria and approach, and some test results.

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