scholarly journals Research on the influence of fuel gas on energy characteristics of a gas turbine

2019 ◽  
Vol 124 ◽  
pp. 05063 ◽  
Author(s):  
G.E. Marin ◽  
B.M. Osipov ◽  
D.I. Mendeleev

The purpose of this paper is to study and analyze the gas turbine engine and the thermodynamic cycle of a gas turbine. The article describes the processes of influence of the working fluid composition on the parameters of the main energy gas turbines, depending on the composition of the fuel gas. The calculations of the thermal scheme of a gas turbine, which were made using mathematical modeling, are given. As a result of research on the operation of the GE PG1111 6FA gas turbine installation with various gas compositions, it was established that when the gas turbine is operating on different fuel gases, the engine efficiency changes. The gas turbine efficiency indicators were determined for various operating parameters and fuel composition. The impact of fuel components on the equipment operation is revealed.

Author(s):  
Thomas Wagner ◽  
Robert J. Burke

The desire to maintain power plant profitability, combined with current market fuel gas pricing is forcing power generation companies to constantly look for ways to keep their industrial gas turbine units operating at the highest possible efficiency. Gas Turbines Operation requires the compression of very large quantities of air that is mixed with fuel, ignited and directed into a turbine to produce torque for purposes ranging from power generation to mechanical drive of pumping systems to thrust for air craft propulsion. The compression of the air for this process typically uses 60% of the required base energy. Therefore management of the compression process efficiency is very important to maintain overall cycle efficiency. Since fouling of turbine compressors is almost unavoidable, even with modern air filter treatment, and over time results in lower efficiency and output, compressor cleaning is required to maintain gas turbine efficiency.


Author(s):  
Raik C. Orbay ◽  
Magnus Genrup ◽  
Pontus Eriksson ◽  
Jens Klingmann

When low calorific value gases are fired, the performance and stability of gas turbines may deteriorate due to a large amount of inertballast and changes in working fluid properties. Since it is rather rare to have custom-built gas turbines for low lower heating value (LHV) operation, the engine will be forced to operate outside its design envelope. This, in turn, poses limitations to usable fuel choices. Typical restraints are decrease in Wobbe index and surge and flutter margins for turbomachinery. In this study, an advanced performance deck has been used to quantify the impact of firing low-LHV gases in a generic-type recuperated as well as unrecuperated gas turbine. A single-shaft gas turbine characterized by a compressor and an expander map is considered. Emphasis has been put on predicting the off-design behavior. The combustor is discussed and related to previous experiments that include investigation of flammability limits, Wobbe index, flame position, etc. The computations show that at constant turbine inlet temperature, the shaft power and the pressure ratio will increase; however, the surge margin will decrease. Possible design changes in the component level are also discussed. Aerodynamic issues (and necessary modifications) that can pose severe limitations on the gas turbine compressor and turbine sections are discussed. Typical methods for axial turbine capacity adjustment are presented and discussed.


Author(s):  
K. Mathioudakis ◽  
N. Aretakis ◽  
A. Tsalavoutas

The paper presents an analysis of the effect of changing the fuel on the performance of industrial gas turbines and examines the impact of such a change on methods used for engine condition assessment and fault diagnostics. A similar analysis is presented for the effects of water injection in the combustion chamber (which is usually done for reducing NOx emissions). First, the way of incorporating the effect of fuel changes and water injection into a computer model of gas turbine performance is described. The approach employed is based on the change of (a) working fluid properties, (b) turbomachinery components performance. The model is then used to derive parameters indicative of the “health” of a gas turbine and thus diagnose the presence of deterioration or faults. The impact of ignoring the presence of an altered fuel or injected water is shown to be of a magnitude that would render a diagnostic technique that does not incorporate these effects ineffective. On the other hand, employing the appropriate physical modeling makes the diagnostic methods robust and insensitive to such changes, being thus able to provide useful diagnostic information continuously during the use of a gas turbine.


Author(s):  
E. A. Ogiriki ◽  
Y. G. Li ◽  
Th. Nikolaidis

Thermal barrier coatings (TBCs) have been widely used in the power generation industry to protect turbine blades from damage in hostile operating environment. This allows either a high turbine entry temperature (TET) to be employed or a low percentage of cooling air to be used, both of which will improve the performance and efficiency of gas turbine engines. However, with continuous increases in TET aimed at improving the performance and efficiency of gas turbines, TBCs have become more susceptible to oxidation. Such oxidation has been largely responsible for the premature failure of most TBCs. Nevertheless, existing creep life prediction models that give adequate considerations to the effects of TBC oxidation on creep life are rare. The implication is that the creep life of gas turbines may be estimated more accurately if TBC oxidation is considered. In this paper, a performance-based integrated creep life model has been introduced with the capability of assessing the impact of TBC oxidation on the creep life and performance of gas turbines. The model comprises of a thermal, stress, oxidation, performance, and life estimation models. High pressure turbine (HPT) blades are selected as the life limiting component of gas turbines. Therefore, the integrated model was employed to investigate the effect of several operating conditions on the HPT blades of a model gas turbine engine using a creep factor (CF) approach. The results show that different operating conditions can significantly affect the oxidation rates of TBCs which in turn affect the creep life of HPT blades. For instance, TBC oxidation can speed up the overall life usage of a gas turbine engine from 4.22% to 6.35% within a one-year operation. It is the objective of this research that the developed method may assist gas turbine users in selecting the best mission profile that will minimize maintenance and operating costs while giving the best engine availability.


Author(s):  
Majed Sammak ◽  
Marcus Thern ◽  
Magnus Genrup

Cooling is essential in all modern high-temperature gas turbines. Turbine cooling is mainly a function of gas entry temperature, which plays the key role in overall gas turbine performance. High turbine entry temperatures can be achieved through appropriate selection of blade cooling method and blade material. The semi-closed oxy-fuel combustion combined cycle (SCOC-CC) operates at the same high entry gas temperature, hence blade cooling is necessary. The aim of this paper was to calculate the required turbine cooling in oxy-fuel gas turbines and compare it to the required turbine cooling in conventional gas turbines. The approach of the paper was to evaluate the thermodynamic and aerodynamic factors affecting turbine cooling with using the m*-model. The results presented in the paper concerned a single turbine stage at a reference diameter. The study showed greater cooling effectiveness in conventional gas turbines, but a greater total cooled area in oxy-fuel gas turbines. Consequently, the calculated total required cooling mass flow was close in the both single stage turbines. The cooling requirement and cooled area for a conventional and oxy-fuel twin-shaft gas turbine was also examined. The gas turbine was designed with five turbine stages. The analysis involved various turbine power and combustion outlet temperatures (COT). The results showed that the total required cooling mass flow was proportional to turbine power because of increasing gas turbine inlet mass flow. The required cooling mass flow was proportional to COT as the blade metal temperature is maintained at acceptable limit. The analysis revealed that required cooling for oxy-fuel gas turbines was higher than for conventional gas turbines at a specific power or specific COT. This is due to the greater cooled area in oxy-fuel gas turbines. The cooling effectiveness of conventional gas turbines was greater, which indicated higher required cooling. However, the difference in cooling effectiveness between conventional and oxy-fuel gas turbines was less in rear stages. The cooling mass flow as percentage of gas turbine inlet mass was slightly higher in conventional gas turbines than in oxy-fuel gas turbines. The required cooling per square meter of cooled area was used as a parameter to compare the required cooling for oxy-fuel and conventional gas turbines. The study showed that the required cooling per cooled area was close in both studied turbines.


1974 ◽  
Author(s):  
R. B. Schiefer ◽  
D. A. Sullivan

The current shortage of conventional gas turbine fuels has created the need for new sources of “clean” fuel. One of the most promising new fuels is low Btu gaseous fuel, such as produced by air injected coal or oil gasifiers or other chemical processes. The various sources of low Btu fuels and their combustion characteristics are discussed. To burn many of the low Btu fuels in the 100–300 Btu/scf range necessitates certain design modifications to the gas turbine originally optimized for high energy fuels. The extent of the modification depends greatly on the low Btu fuel. The impact of low Btu fuels on the gas turbine thermodynamic cycle performance and environmental performance is very encouraging. From the environmental viewpoint, low Btu fuels promise to be “clean” fuels while providing increased output at higher thermal cycle efficiencies than achieved with conventional fuels.


Author(s):  
Colin F. McDonald

For closed-cycle gas turbines, in a size to meet utility power generation needs, the selection of helium as the working fluid represents the best solution in terms of the overall power conversion system considering the differing requirements of the turbomachinery and heat exchangers. Helium is well suited for the nuclear Brayton cycle because it is neutronically inert. The impact of helium’s unique properties on the performance and size of the power conversion system components is discussed in this paper. The helium gas turbine plants, that have operated were based on 1950s and 1960s technology, represent a valuable technology base in terms of practical experience gained. However, the design of the Gas Turbine Modular Helium Reactor (GT-MHR), which could see utility service in the first decade of the 21st century will utilize turbomachinery and heat exchanger technologies from the combustion gas turbine and aerospace industries. An understanding of how the design of power conversion systems for closed-cycle plants and combustion gas turbines are affected by the working fluids (i.e., helium and air, respectively) is the major theme of this paper.


Author(s):  
Raik C. Orbay ◽  
Magnus Genrup ◽  
Pontus Eriksson ◽  
Jens Klingmann

When low calorific value gases are fired, the performance and stability of gas turbines may deteriorate due to a large amount of inert ballast and changes in working fluid properties. Since it is rather rare to have custom-built gas turbines for low Lower Heating Value (LHV) operation, the engine will be forced to operate outside its design envelope. This, in turn, poses limitations to usable fuel choices. Typical restraints are decrease in Wobbe-index and surge- and flutter-margins for turbomachinery. In this study, an advanced performance deck has been used to quantify the impact of firing low-LHV gases in a generic type gas turbine. A single-shaft gas turbine characterized by a compressor and an expander map is considered. Emphasis has been put on predicting the off-design behavior. The combustor is discussed and related to previous experiments which include investigation of flammability limits, Wobbe-index, flame position, etc. The computations show that at constant turbine inlet temperature (TIT), the shaft power and the pressure ratio will increase, however the surge margin will decrease. Possible design changes in the component level are also discussed. Aerodynamic issues (and necessary modifications) that can pose severe limitations on the gas turbine compressor- and turbine sections are discussed. Typical methods for axial turbine capacity adjustment are presented and discussed.


2021 ◽  
Vol 13 (22) ◽  
pp. 12566
Author(s):  
Oleg Bazaluk ◽  
Valerii Havrysh ◽  
Oleksandr Cherednichenko ◽  
Vitalii Nitsenko

Currently, offshore areas have become the hotspot of global gas and oil production. They have significant reserves and production potential. Offshore platforms are energy-intensive facilities. Most of them are equipped with gas turbine engines. Many technologies are used to improve their thermal efficiency. Thermochemical recuperation is investigated in this paper. Much previous research has been restricted to analyzing of the thermodynamic potential of the chemically recuperated gas turbine cycle. However, little work has discussed the operation issues of this cycle. The analysis of actual fuel gases for the steam reforming process taking into account the actual load of gas turbines, the impact of steam reforming on the Wobbe index, and the impact of a steam-fuel reforming process on the carbon dioxide emissions is the novelty of this study. The obtained simulation results showed that gas turbine engine efficiency improved by 8.1 to 9.35% at 100% load, and carbon dioxide emissions decreased by 10% compared to a conventional cycle. A decrease in load leads to a deterioration in the energy and environmental efficiency of chemically recuperated gas turbines.


Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1499 ◽  
Author(s):  
Dominika Matuszewska ◽  
Piotr Olczak

Power conversion systems based on the Organic Rankine Cycle (ORC) have been identified as a potential technology especially in converting low-grade renewable sources or waste heat. However, it is necessary to improve efficiency of ORC systems. This paper focuses on use of low geothermal resources (for temperature range of 80–128 °C and mass flow 100 kg/s) by using modified ORC. A modification of conventional binary power plant is conducted by combining gas turbines to increase quality of steam from a geothermal well. An analysis has been conducted for three different working fluids: R245fa, R1233zd(E) and R600. The paper discusses the impact of parameter changes not only on system efficiency but on other performance indicators. The results were compared with a conventional geothermal Organic Rankine Cycle (ORC). Increasing of geothermal steam quality by supplying exhaust gas from a gas turbine to the installation has a positive effect on the system efficiency and power. The highest efficiency of the modified ORC system has been obtained for R1233zd(E) as a working fluid and it reaches values from 12.21% to 19.20% (depending on the temperature of the geothermal brine). In comparison, an ORC system without gas turbine support reaches values from 9.43% to 17.54%.


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