Gas Turbine Combustor Analysis

1975 ◽  
Vol 97 (4) ◽  
pp. 610-618
Author(s):  
D. A. Sullivan

The pressure, temperature, and fuel-to-air ratio of a gas turbine combustor vary with ambient conditions, machine speed, and load. Only a few of these parameters are independent. An analysis has been developed which predicts the combustor operating parameters. The analysis includes low heating value fuel combustion, water injection, and three modes of steam injection. The analysis is used to predict the combustor operation for a simple-cycle gas turbine, but it is not restricted to this case. In addition, a simplified analysis is deduced and shown to be surprisingly accurate. Special solutions are presented which permit direct calculation of the firing temperatures, fuel heating value, or air extraction required to achieve a specified compressor pressure ratio. Finally, the analysis is compared with experimental results.

Author(s):  
Ibrahim Sinan Akmandor ◽  
O¨zhan O¨ksu¨z ◽  
Sec¸kin Go¨kaltun ◽  
Melih Han Bilgin

A new methodology is developed to find the optimal steam injection levels in simple and combined cycle gas turbine power plants. When steam injection process is being applied to simple cycle gas turbines, it is shown to offer many benefits, including increased power output and efficiency as well as reduced exhaust emissions. For combined cycle power plants, steam injection in the gas turbine, significantly decreases the amount of flow and energy through the steam turbine and the overall power output of the combined cycle is decreased. This study focuses on finding the maximum power output and efficiency of steam injected simple and combined cycle gas turbines. For that purpose, the thermodynamic cycle analysis and a genetic algorithm are linked within an automated design loop. The multi-parameter objective function is either based on the power output or on the overall thermal efficiency. NOx levels have also been taken into account in a third objective function denoted as steam injection effectiveness. The calculations are done for a wide range of parameters such as compressor pressure ratio, turbine inlet temperature, air and steam mass flow rates. Firstly, 6 widely used simple and combined cycle power plants performance are used as test cases for thermodynamic cycle validation. Secondly, gas turbine main parameters are modified to yield the maximum generator power and thermal efficiency. Finally, the effects of uniform crossover, creep mutation, different random number seeds, population size and the number of children per pair of parents on the performance of the genetic algorithm are studied. Parametric analyses show that application of high turbine inlet temperature, high air mass flow rate and no steam injection lead to high power and high combined cycle thermal efficiency. On the contrary, when NOx reduction is desired, steam injection is necessary. For simple cycle, almost full amount of steam injection is required to increase power and efficiency as well as to reduce NOx. Moreover, it is found that the compressor pressure ratio for high power output is significantly lower than the compressor pressure ratio that drives the high thermal efficiency.


Author(s):  
G. L. Touchton

Steam or water injection has become the state-of-the-art abatement technique for NOx, with steam strongly preferred for combined-cycle application. In combined-cycle plants, the degradation of the plant efficiency due to steam injection into the gas turbine combustor provides a powerful incentive for minimizing this flow over the entire plant operating map. This paper presents the results of extensive tests carried out on a variety of gas turbine combustor designs. Both test stand and field test data are presented. The usual fuel in the tests is methane; however, some data are presented for combustion of No. 2 distillate oil and intermediate Btu gas fuel. Similarly, the usual inert injected is steam, but some water injection data are included for comparison. The results support the conclusions: 1. Steam and water injection suppress NOx exclusively through thermal mechanisms, i.e., by lowering the peak flame temperature. 2. Design changes have little effect on NOx suppression effectiveness of steam or water in jet-stirred or swirl-mixed combustors. 3. Primary zone injection of steam in methane-fueled, jet-stirred combustors is equally effective whether the steam enters with an air stream or with the fuel stream. 4. Water-to-fuel ratio corrected to equivalent energy content correlates NOx suppression effectiveness for turbulent diffusion flame combustors.


1985 ◽  
Vol 107 (3) ◽  
pp. 706-713 ◽  
Author(s):  
G. L. Touchton

Steam or water injection has become the state-of-the-art abatement technique for NOx, with steam strongly preferred for combined-cycle application. In combined-cycle plants, the degradation of the plant efficiency due to steam injection into the gas turbine combustor provides a powerful incentive for minimizing this flow over the entire plant operating map. This paper presents the results of extensive tests carried out on a variety of gas turbine combustor designs. Both test stand and field test data are presented. The usual fuel in the tests is methane; however, some data are presented for combustion of No. 2 distillate oil and intermediate Btu gas fuel. Similarly, the usual inert injected is steam, but some water injection data are included for comparison. The results support the conclusions: 1. Steam and water injection suppress NOx exclusively through thermal mechanisms, i.e., by lowering the peak flame temperature. 2. Design changes have little effect on NOx suppression effectiveness of steam or water in jet-stirred or swirl-mixed combustors. 3. Primary zone injection of steam in methane-fueled, jet-stirred combustors is equally effective whether the steam enters with an air stream or with the fuel stream. 4. Water-to-fuel ratio corrected to equivalent energy content correlates NOx suppression effectiveness for turbulent diffusion flame combustors.


Author(s):  
Kousuke Nishida ◽  
Toshimi Takagi ◽  
Shinichi Kinoshita

There is a demand for developments of a distributed energy system using a small scale gas turbine. The steam injection configurations can improve the performances of the simple and regenerative gas turbine cycles. In this study, the thermal efficiency and exergy loss of two types of regenerative steam injection gas turbine (RSTIG) system are analyzed, and the performances of them are compared with those of the regenerative, water injection and STIG systems. It is noted that the optimum pressure ratio of the RSTIG systems becomes relatively low. The thermal efficiency of the RSTIG systems is higher than that of the water injection and STIG systems. The specific power of them is larger than that of the regenerative cycle. The steam injection configurations can be applied to the flexible heat and power generation system. The total efficiency of the heat and power generation of the RSTIG systems reaches more than 70% (HHV).


1980 ◽  
Author(s):  
J. R. Grant ◽  
T. E. Holladay ◽  
F. H. Boenig ◽  
R. L. Duncan

Industrial turbines fired on medium heating value (MHV) gas (nominally 300 Btu/scf) synthesized from coal offer an attractive alternative means of producing electrical power in the future. Peak flame temperatures resulting from combustion of this MHV gas in conventional diffusion flame combustors may be comparable to those of natural gas, yielding undesirably high concentrations of NOx. This paper describes an EPRI-sponsored program conducted to demonstrate a MHV gas turbine combustor capable of meeting EPA NOx requirements without water injection. Program objectives were to design, fabricate, and test three MHV combustor configurations and to demonstrate NOx emissions concentrations of 15 ppmv (dry basis) or less at a burner inlet pressure of 1.27 atm: Design of the combustors was based on a lean-premix fuel metering concept. Tests were conducted in a single-can combustor rig at simulated engine conditions ranging from 40 to 125 percent of engine baseload (74 MW).


1978 ◽  
Vol 100 (4) ◽  
pp. 640-646 ◽  
Author(s):  
P. Donovan ◽  
T. Cackette

A set of factors which reduces the variability due to ambient conditions of the hydrocarbon, carbon monoxide, and oxides of nitrogen emission indices has been developed. These factors can be used to correct an emission index to reference day ambient conditions. The correction factors, which vary with engine rated pressure ratio for NOx and idle pressure ratio for HC and CO, can be applied to a wide range of current technology gas turbine engines. The factors are a function of only the combustor inlet temperature and ambient humidity.


Author(s):  
M. F. Bardon ◽  
J. A. C. Fortin

This paper examines the possibility of injecting methanol into the compressor of a gas turbine, then dissociating it to carbon monoxide and hydrogen so as to cool the air and reduce the work of compression, while simultaneously increasing the fuel’s heating value. A theoretical analysis shows that there is a net reduction in compressor work resulting from this dissociative intercooling effect. Furthermore, by means of a computer cycle model, the effects of dissociation on efficiency and work per unit mass of airflow are predicted for both regenerated and unregenerated gas turbines. The effect on optimum pressure ratio is examined and practical difficulties likely to be encountered with such a system are discussed.


Author(s):  
Malath I. Arar

Gas Turbine, GT, control methodology applied to power generation is being evaluated. Corrected parameter control methodology has been adopted for this purpose. This method uses the corrected physical ambient conditions such as pressure, temperature and humidity in controlling the GT operations. Humidity correction becomes increasingly important in this control scheme. The following are the reasons for accurate and robust humidity measurement: (1) Humidity measurement is important to the operation control of the dry low NOX, DLN, combustor system. (2) GT inlet performance enhancing devices, such as evaporative coolers and inlet foggers, depend upon the accurate humidity measurement to determine the amount of water needed for inlet temperature depression. (3) Humidity measurement is used to determine the amount of water to be injected in the combustor for NOX abatement when running on liquid fuel as an alternative to natural gas fuel. In order to obtain accurate and reliable humidity readings, several commercially available humidity sensors were extensively tested and evaluated in a controlled laboratory environment. The sensors were tested for their measurement accuracy, saturation conditions, power interruption and surge, sudden temperature changes and medium air speed. Test ambient temperature ranges from −30 °C to 50 °C. This covers the operating ambient conditions range for the Gas Turbine. The test criterion is that the error in the response of the sensor shall not exceed ±1 °C from the test reference for all the tests conducted on the sensors. The combustion requirements for Dry Low NOX operations and mode transfer dictate this criterion. Also, as a DLN requirement, error in specific humidity shall not exceed 0.904 g/g of air. This test criterion also satisfies the water injection requirements for NOX abatement and inlet performance enhancing devices. The results show that for ±1 °C error in the sensor measurement, the resulting error in NOX calculation is less than 0.2 ppm. The test results show that all sensors except the current one in use have met the test criterion. The current sensor, General Eastern DT-2, has a large measurement error in the order of ±5 °C. Programs have been launched to field test and evaluate these sensors in order to replace the current one.


Author(s):  
Anoop Kumar Shukla ◽  
Onkar Singh

Gas/steam combined cycle power plants are extensively used for power generation across the world. Today’s power plant operators are persistently requesting enhancement in performance. As a result, the rigour of thermodynamic design and optimization has grown tremendously. To enhance the gas turbine thermal efficiency and specific power output, the research and development work has centered on improving firing temperature, cycle pressure ratio, adopting improved component design, cooling and combustion technologies, and advanced materials and employing integrated system (e.g. combined cycles, intercooling, recuperation, reheat, chemical recuperation). In this paper a study is conducted for combining three systems namely inlet fogging, steam injection in combustor, and film cooling of gas turbine blade for performance enhancement of gas/steam combined cycle power plant. The evaluation of the integrated effect of inlet fogging, steam injection and film cooling on the gas turbine cycle performance is undertaken here. Study involves thermodynamic modeling of gas/steam combined cycle system based on the first law of thermodynamics. The results obtained based on modeling have been presented and analyzed through graphical depiction of variations in efficiency, specific work output, cycle pressure ratio, inlet air temperature & density variation, turbine inlet temperature, specific fuel consumption etc.


Author(s):  
Andrea Lazzaretto ◽  
Andrea Toffolo ◽  
Sebastiano Trolese

Precise performance evaluation at design and off-design operations is needed for a correct management of power plants. This need is particularly strong in gas turbine power plants which can quickly react to load variations and are very sensitive to ambient conditions. The paper aims at presenting a simple tool to determine the values of the thermodynamic quantities in each point of the plant and the overall plant performances of a real gas turbine plant. Starting from experimental data, a zero-dimensional model is developed which properly considers the effect of ambient conditions and water injection for pollutant abatement at different load settings under the action of the control system. An emission model taken from the literature is also included, after tuning on experimental data, to predict carbon monoxide and nitrogen oxide pollution.


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