Evaluation of the Influence of Ambient Temperature on the Performance of the Trans-Amadi Gas Turbine Plant

This paper examines the effects of ambient temperature on the Trans-Amadi gas turbine power station Phase II. The investigation took thirteen (13) months (January 2012 to January 2013) during which plant data were monitored and operational Logsheets like turbine logsheets, plant—auxiliaries’ logsheets and generator logsheets were studied. The gas turbine (GT) that was under investigation was GT-2: MS5001 Nuovopignone with designed installed capacity of 25.0 Megawatts (MW). The result of the study shows that a 1℃ rise of the ambient temperature is responsible for the following: 0% - 0.12% decrease in the power output, 0% - 0.12% increase in the power differential, 0% - 1.17% decrease in the thermal efficiency, 0% - 27.18% increase in the heat rate and 0% - 3.57% increase in the specific fuel consumption. An ambient temperature of 30℃ is found to yield minimal fuel consumption.

Optimization of Gas Turbine Exhaust Volute Flow Loss

The exhaust volute is a device that can change the exhaust direction of the ship’s gas turbine to reduce the flow loss of the high-temperature and high-speed turbine exhaust gas in the box-type exhaust volute,thereby improving its power output performance.This paper first investigates the internal flow field characteristics of the exhaust volute via numerical simulation and reveals the main source of the internal resistance loss of the volute.On the premise of not affecting the installation size of the volute and matching it with other components in the cabin,the design scheme of volute bottom shunt and volute chamfer are then optimized in accordance with the flow characteristics inside the volute.Numerical simulation results show that the partial flow structure at the bottom of the volute can effectively improve the low-velocity region and the vortex flow at the bottom of the volute,and the chamfered angle scheme can control the regular expansion and compression of the airflow.When the volute adopts the appropriate chamfer angle and the bottom split-flow structure,the total pressure loss can be reduced by 19.6%,and the static pressure recovery coefficient can be increased by 42.05%.

Evaluation of the Gas Turbine Inlet Temperature with Relation to the Excess Air

This paper shows the effect of excess air on combustion gas temperature at turbine inlet, and how it determines power and thermal efficiency of a gas turbine at different pressure ratios and excess air. In such a way an analytic Equation that allows calculating the turbine inlet temperature as a function of excess air, pressure ratio and relative humidity is given. Humidity Impact on excess air calculation is also analyzed and presented. Likewise it is demonstrated that dry air calculations determine a higher level for calculations that can be performed on wet air.

Surface Temperatures Determination with Influencing Convective and Radiative Thermal Resistance Parameters of Combustor of Gas Turbine

Surface temperatures were determined with due consideration of the influencing thermal conditions of conductive, convective and radiative heat. A general condition of heat influx to a point was formulated with the end effect of such influx to the receiving point. It was noted that the heat flow will cause a rate of change of internal energy of the point. Based on the theory of the rate of change of internal energy, a combustor model of cylindrical cross-section was used to generate out the timely temperature equation. Further work was done on this model equation to convert it to non-dimensional. The conversion of this equation was very essential in summing up the parameters that can influence the timely generation of the temperatures. Interestingly, it is noted that when a material withstands temperatures, it will equally withstand the thermal stresses that inherently will be developed in it. From the results, the work came up with a table showing the range of these slope figures of equations, a point was also found for a vital recommendation for further studies, where such figures can be used to check the suitability for thermal stress levels and the lifetime of combustor of such thickness.

Retrofit of 350-MW Supercritical Boiler Based on the Analysis on Exhaust Gas Temperature

Since the first batch of 350-MW supercritical utility boilers was put into operation, the exhaust flue gas temperature of the boilers has always been higher than the designed value. The main reason is that the heat absorbed by the air heater is not sufficient. In Huaneng Dongfang Power Plant, the exhaust flue gas temperature is lowered through modifications to the economizer and the air heater. The experimental results reveal that every year, each boiler could save 3 850 tons of standard coal and reduce 85 tons of SO2 and 9 000 tons of CO2 respectively after retrofit.

Correlation of Performance, Exhaust Gas Temperature and Speed of a Spark Ignition Engine Using Kiva4

The objective of this study was to investigate performance characteristics of a spark ignition engine, particularly, the correlation between performance, exhaust gas temperature and speed, using Kiva4. Test data to validate kiva4 simulation results were conducted on a 3-cylinder, four-stroke Volkswagen (VW) Polo 6 TSI 1.2 gasoline engine. Three different tests were, therefore, carried out. In one set, variations in exhaust gas temperature were studied by varying the engine load, while keeping the engine speed constant. In another test, exhaust gas temperature variations were studied by keeping the engine at idling whilst varying the speeds. A third test involved studying variations in exhaust gas temperature under a constant load with variable engine speeds. To study variations in exhaust gas temperatures under test conditions, a basic grid/mesh generator, K3PREP, was employed to write an itape17 file comprising of a 45° asymmetrical mesh. This was based on the symmetry of the combustion chamber of the engine used in carrying out experimental tests. Simulations were therefore performed based on the input parameters established in the conducted tests. Simulations with the kiva4 code showed a significant predictability of the performance characteristics of the engine. This was evident in the appreciable agreement obtained in the simulation results when compared with the test data, under the considered test conditions. A percentage error, between experimental results and results from simulations with the kiva4 code of only between 2% to 3% was observed.

Thermodynamic Performance Analysis of E/F/H-Class Gas Turbine Combined Cycle with Exhaust Gas Recirculation and Inlet/Variable Guide Vane Adjustment under Part-Load Conditions

Exhaust gas recirculation control(EGRC),an inlet air heating technology,can be utilized in combination with inlet/variable guide vane control(IGV/VGVC) and fuel flow control(FFC) to regulate the load,thereby effectively improving the part-load(i.e.,off-design) performance of the gas turbine combined cycle(GTCC).In this study,the E-,F-,and H-Class EGR-GTCC design and off-design system models were established and validated to perform a comparative analysis of the part-load performance under the EGR-IGV-FFC and conventional IGV-FFC strategies in the E/F/H-Class GTCC.Results show that EGR-IGV-FFC has considerable potential for the part-load performance enhancement and can show a higher combined cycle efficiency than IGV-FFC in the E-,F-,and H-Class GTCCs.However,the part-load performance improvement in the corresponding GTCC was weakened for the higher class of the gas turbine because of the narrower load range of EGR action and the deterioration of the gas turbine performance.Furthermore,EGR-IGV-FFC was inferior to IGV-FFC in improving the performance at loads below 50% for the H-Class GTCC.The results obtained in this paper could help guide the application of EGR-IGV-FFC to enhance the part-load performance of various classes of GTCC systems.

Experimental Study of Fuel-Air Mixing and Dilution Jets on Outlet Temperature Distribution in a Small Gas Turbine Combustor

Experimental analysis was conducted to study the impact of fuel-air mixing and dilution jet on the temperature distribution in a small gas turbine combustor using various optical diagnostic techniques.The strength and velocity of the swirler at the venturi exit were adjusted to modify the fuel-air mixture,which is presumed to dominate the heat release of the main combustion zone.Additionally,the dilution hole configuration,including the number and size of the holes,was varied to investigate the dilution effect on outlet temperature distribution.Various optical diagnostic techniques,such as particle image velocimetry,planar Mie scattering,and OH~*chemiluminescence,were used to measure the flow field,fuel spray distribution,and flame structure,respectively.A reduction in swirling strength led to a decrease in the average flow rate in the throat,which improved the structure and symmetry of the axial vortex system in the sleeve,enhanced the mixing of fuel and gas in the dome swirling air,and ultimately,improved the temperature uniformity of the heat release zone.Compared to larger and sparse dilution jets,smaller and dense dilution jets tended to generate hot spots shifted towards the radial middle area.

Technical Measures and Selections for Reducing Flue Gas Heat Loss of Large Coal-Fired Boilers

The main technologies for reducing flue gas heat loss of pulverized coal-fired boilers are introduced, and the suitability of these technologies for boiler operation and the principles for selection of these technologies are explored. The main conclusions are： 1） the non-equilibrium control over flue gas flow rates at the inlet of the air heater and the reversal rotation of the air heater rotator should be popularized as regular technologies in large boilers; 2） increasing the area of the air heater to reduce the flue gas heat loss in pulverized coal-fired boilers should be the top option and increasing the area of the economizer be the next choice; 3） low- pressure economizer technology could save energy under special conditions and should be compared with the technology of increasing economizer area in terms of technical economics when the latter is feasible; 4） the hot primary air heater is only suitable to the pnlvefizing system with a large amount of cold air mixed.

Empirical Model to Calculate the Thermodynamic Wet-Bulb Temperature of Moist Air

An equation model for calculating the adiabatic temperature of the wet-bulb thermometer has been obtained empirical fit through a meteorological database, specificly a trough relative humidity and air temperature. A comparison of the results of calculations with the use of this equation and from meteorological database was made. The model deducted of the comparison is valid for a dry bulb temperature range of 3°C to 35°C and for relative humidity percentage in a range of 7% to 97%. Normalized errors are less than 5.5%. It means a maximum variation of 0.55°C from data. However, this variation from error represents only 3.6% of the data sample. The equation model was satisfactory.

Estimation of Service Lives and Operating Temperature Ranges of High-Temperature Lubricating Oils Using Thermal Analysis

Development of gas turbine oils that can be used in higher temperature conditions remains the greatest technological challenge. Though the maximum operating temperature of conventional lubricating oils is generally set around 100 ℃, or 140 ℃ for scavenged oils, it is predicted that the future will require oils to function at 200 ℃ or above. To find a clue to developing oils that can be used at higher temperatures, this study attempted to estimate service lives and operating temperature ranges of certain oils, including oils conforming to MIL-PRF-23699, which are deemed promising candidates for high-temperature applications, by analyzing their reaction rates of degradation and degeneration by oxidation. Among a number of methods used in the analyses of reaction rates, this study chose thermo-gravimetry （TG）, with which estimations can be made relatively easily.

Improvement of part-load performance of gas turbine by adjusting compressor inlet air temperature and IGV opening

A novel adjusting method for improving gas turbine(GT)efficiency and surge margin(SM)under partload conditions is proposed.This method adopts the inlet air heating technology,which uses the waste heat of lowgrade heat source and the inlet guide vane(IGV)opening adjustment.Moreover,the regulation rules of the compressor inlet air temperature and the IGV opening are studied comprehensively to optimize GT performance.A model and calculation method for an equilibrium running line is adopted based on the characteristic curves of the compressor and turbine.The equilibrium running lines calculated through the calculation method involve three part-load conditions and three IGVopenings with different inlet air temperatures.The results show that there is an optimal matching relationship between IGV opening and inlet air temperature.For the best GT performance of a given load,the IGV could be adjusted according to inlet air temperature.In addition,inlet air heating has a considerable potential for the improvement of part-load performance of GT due to the increase in compressor efficiency,combustion efficiency,and turbine efficiency as well as turbine inlet temperature,when inlet air temperature is lower than the optimal value with different IGV openings.Further,when the IGV is in a full opening state and an optimal inlet air temperature is achieved by using the inlet air heating technology,GT efficiency and SM can be obviously higher than other IGVopenings.The IGV can be left unadjusted,even when the load is as low as 50%.These findings indicate that inlet air heating has a great potential to replace the IGV to regulate load because GT efficiency and SM can be remarkably improved,which is different from the traditional viewpoints.

Conjugate Calculation of Gas Turbine Vanes Cooled with Leading Edge Films

Conjugate calculation methodology is used to simulate the C3X gas turbine vanes cooled with leading edge films of 'shower- head' type. By comparing calculated results of different turbulence models with the measured data, it is clear that calculation with the transition model can better simulate the flow and heat transfer in the boundary layers with leading edge film cooling. In the laminar boundary layers, on the upstream suction side, the film cooling flow presents 3D turbulent characteristics before tran...

Study on Strength and Life of Anisotropic Single Crystal Blade - Part I: Crystallographic Constitutive Models and Applications

The single crystal blade is one of the key technologies for improving the performance, durability and reliability of aero-engines and ground gas-turbine engines. However, the anisotropic mechanical properties of the single crystal material makes a great deal of difficulties on the development and the application of the single crystal blade, which is a challenge for the engineering application of the single crystal superalloy and the theoretic bases of the application. Some researches on the strength analysis and the life prediction of the anisotropic single crystal blade were carried out by the authors' research team. They are as follows. The crystallographic constitutive models for the plastic and the creep behaviors and the method of the rupture life prediction were established and verified. The tensile or the creep experiments for DD3 single crystal alloy with different orientations under different temperatures and different tensile rates or under different temperatures and different stress levels were carried out. The experimental data and the anisotropic properties at intermediate and high temperatures revealed by the experiments are significant for the application of the single crystal alloy. In addition, the experimental research for a kind of single crystal blade was also made. As the application of the researches the strength analysis and the life prediction were carried out for the single crystal blade of a certain aero-engine. In this part, the constitutive models and their applications are described, and the experimental research work will be described in part II.

Performance Characteristics of n-Butanol-Diesel Fuel Blend Fired in a Turbo-Charged Compression Ignition Engine

In this study, n-butanol-diesel blends were burned in a turbo-charged, direct injection diesel engine where the brake thermal efficiency, (BTE) or brake specific fuel consumption, (BSFC) was compared with that of ethanol-diesel or methanol-diesel blends in another study by other authors. The test blends used were B5, B10 and B20 (where B5 is 5% n-butanol by volume and 95% diesel fuel-DF). In this study, the BTE was higher and the BSFC improved more than in the other study. Because of improved BTE with increasing brake mean effective pressure, BMEP, the BSFC reduced, however the increased shared volume of n-butanol in DF increased BSFC. Adding n-butanol in DF slightly derated the torque, brake power output with increasing speed, and caused a fall in exhaust gas temperatures, (EGT) which improves the volumetric efficiency and reduces compression work. Therefore, a small-shared volume of n-butanol in DF fired in a turbo-charged diesel engine performs better in terms of BTE and BSFC than that of ethanol or methanol blending in DF.

Interaction between Struts and Swirl Flow in Gas Turbine Exhaust Diffusers

The increasing use of gas turbines in combined cycle power plants together with the high amount of kinetic energy in modem gas turbine exhaust flows focuses attention on the design of gas turbine diffusers as the connecting part between the Brayton/Joule and the Rankine parts of the combined cycle. A scale model of a typical gas turbine exhaust diffuser is investigated experimentally. The test rig consists of a radial type, variable swirl generator which provides the exhaust flow corresponding to different gas turbine operating conditions. Static pressure measurements are carried out along the outer diffuser walls and along the hub of the annular part and along the centerline of the conical diffuser. Velocity distributions at several axial positions in the annular and conical diffuser have been measured using a Laser Doppler Velocimeter （LDV）. Pressure recovery coefficients and velocity profiles are depicted as a function of diffuser length for several combinations of swirl strength, tip flow and strut geometries. The diffuser without struts achieved a higher pressure recovery than the diffuser with struts at all swirl angle settings. The diffuser with cylindrical struts achieved a higher pressure recovery than the diffuser with profiled struts at all swirl angle seO.ings. Inlet flows with swirl angles over 18° affected the pressure recovery negatively for all strut configurations.

A step parameters prediction model based on transfer process neural network for exhaust gas temperature estimation after washing aero-engines

The prediction of Exhaust Gas Temperature Margin(EGTM)after washing aeroengines can provide a theoretical basis for airlines not only to evaluate the energy-saving effect and emission reduction,but also to formulate reasonable maintenance plans.However,the EGTM encounters step changes after washing aeroengines,while,in the traditional models,a persistence tendency exists between the prediction results and the previous data,resulting in low accuracy in prediction.In order to solve the problem,this paper develops a step parameters prediction model based on Transfer Process Neural Networks(TPNN).Especially,“step parameters”represent the parameters that can reflect EGTM step changes.They are analyzed in this study,and thus the model concentrates on the prediction of step changes rather than the extension of data trends.Transfer learning is used to handle the problem that few cleaning records result in few step changes for model learning.In comparison with Long Short-Term Memory(LSTM)and Kernel Extreme Learning Machine(KELM)models,the effectiveness of the proposed method is verified on CFM56-5B engine data.

Performance Optimization of Dual Pressure Heat Recovery Steam Generator (HRSG) in the Tropical Rainforest

This work evaluates the performance optimization of heat recovery steam generator system in Afam VI power plant, Rivers State. Nigeria. Steady state monitoring and direct collection of data from the plant was performed including logged data for a period of 12 months. The data were analysed using various energy equations. Hysys software was used to model the temperature across the heating surfaces, and MATLAB software was used to determine the heat transfer coefficient, heat duties, steam flow, effectiveness of the HRSG. The optimization technique was carried out by varying the exhaust gas flow, exhaust gas temperature, steam pressure and the theoretical introduction of duct burner for supplementary firing. The results show that between 490℃ and 526℃, the percentage increase in the overall heat absorbed in the HRSG is 37.39%. It also show that for an increase in the exhaust gas mass flow by 80 kg/s, the steam generation increase by 19.29% and 18.18% for the low and high pressure levels respectively. The overall result indicates an improvement in the HRSG energy efficiency and steam generation. As the exhaust gas mass flow and temperature increases, the steam generation and system effectiveness greatly improved under the various considerations, which satisfy the research objective.

Oxidation Behaviour of a Newly Developed Superalloy

The current paper explains the oxidation behaviour of a newly developed nickel-based superalloy in simulating aero gas turbine engine conditions. The results showed that the new superalloy is highly susceptible to high temperature oxidation. Within three of hours of oxidation, extensive oxide scales were formed. The formed oxide scales were ana-lysed with electron dispersive spectroscopy (EDS) and morphology was studied with scanning electron microscope (SEM) for varied oxidation times. The oxidation products were determined with XRD and cross sections of all the oxi-dised superalloys were also studied. The elemental distribution of all the superalloys after oxidation was also studied with a view to understand and compare the characteristics of the new superalloy with other superalloys. Finally, an oxidation mechanism that is responsible for its faster degradation under elevated temperatures was established based on the results obtained with different techniques and presented in detail.

Research and Development of Hot Primary Air Heater for Coal-Fired Boilers in Power Plant

The reasons of introducing cold air into pulverizer are analyzed for boilers with large capacity and high parameters. The temperature rises of the exhaust gas are calculated when varying the amount of the cold air. The hot primary air heater, a new technology, is developed to eliminate the cold air from the pulverized coal system. The applications, advantages and disadvantages are introduced in detail for the new device and system. It is concluded that introducing cold air into pulverizer is one of the major factors that causes the exhaust gas temperature of boilers with large capacity to be high. The amount of the cold air could be reduced signif icantly, even to zero in some cases by adopting the hot primary air heater, which drops the exhaust gas temperature of the boiler effectively. The hot primary air heater, which could play part roles of the steam-air heater or the hot air recirculation system, could also be used to adjust the exhaust gas temperature within the range of 20 ℃ by controlling the flow rate of the cooling medium. Moreover, the startup period of the steam-air heater or the hot air recirculation system will be shortened, which is a unique advantage of the hot primary air heater among the measures to drop the exhaust gas temperature.