Turbine Input Research Articles

Techno-economic optimization of biogas-fueled micro gas turbine cogeneration systems in sewage treatment plant

The aim of this paper is to investigate the feasibility of a combined cooling, heating, and power generation system with a micro turbine using biogas as the fuel to supply the heat and electricity demands in a real wastewater treatment plant. The plant is optimized using the system’s total cost rate and the amount of the produced biogas as objective functions. The anaerobic digester is modeled using the ADM1 model. The optimization variables include digester hydraulic retention time, compressor pressure ratio, isentropic compressor efficiency, recuperator pinch time temperature, turbine isentropic efficiency, turbine input temperature, and the number of micro turbines. In the first scenario (business as usual), the optimal values of the system’s total cost rate and the amount of the produced biogas are 0.02561 $/s and 12.6235*103m3/day, respectively. In the environmental scenario, the optimum values of the total cost rate and the biogas flow rate are 0.0652 $/sand 12.6901*103m3/day, respectively. Scenario 1 has lower values of total cost rate and levelized cost of electricity and higher CO2 emissions than scenario 2. The surplus of electricity from the plant may be exported to the grid in the first scenario. However, some electricity will be imported from the grid in scenario 2. Finally, the effects of some important parameters have been assessed on the total cost rate using Sobol sensitivity analysis. Hydraulic retention time, power purchase price, and discount rate have the highest impacts on the system’s total cost rate by 15% while AD temperature has the lowest effect on total cost rate by 6%. In general, the results of this paper could be employed as a decision support tool for policy makers in energy sector as well as wastewater treatment plant managers to supply the energy demand of their plant.

Development and thermodynamic assessment of a novel solar and biomass energy based integrated plant for liquid hydrogen production

In this paper, a combined power plant based on the dish collector and biomass gasifier has been designed to produce liquefied hydrogen and beneficial outputs. The proposed solar and biomass energy based combined power system consists of seven different subplants, such as solar power process, biomass gasification plant, gas turbine cycle, hydrogen generation and liquefaction system, Kalina cycle, organic Rankine cycle, and single-effect absorption plant with ejector. The main useful outputs from the combined plant include power, liquid hydrogen, heating-cooling, and hot water. To evaluate the efficiency of integrated solar energy plant, energetic and exergetic effectiveness of both the whole plant and the sub-plants are performed. For this solar and biomass gasification based combined plant, the generation rates for useful outputs covering the total electricity, cooling, heating and hydrogen, and hot water are obtained as nearly 3.9 MW, 6584 kW, 4206 kW, and 0.087 kg/s in the base design situations. The energy and exergy performances of the whole system are calculated as 51.93% and 47.14%. Also, the functional exergy of the whole system is calculated as 9.18% for the base working parameters. In addition to calculating thermodynamic efficiencies, a parametric plant is conducted to examine the impacts of reference temperature, solar radiation intensity, gasifier temperature, combustion temperature, compression ratio of Brayton cycle, inlet temperature of separator 2, organic Rankine cycle turbine and pump input temperature, and gas turbine input temperature on the combined plant performance.

Failure analysis in a steam turbine stop valve of a thermal power plant

In the current study, the problem of cracking on the stop valve body in a steam turbine related to a thermal power plant is assessed. The problem usually occurs consecutively and almost in identical locations for the power plant's stop valves. To do so, the steam flow path from the developed area at the boiler output to the turbine input is divided into three separate computational domains and numerically simulated. The obtained results of the simulation have been successfully verified using the actual data of the thermal power plant. The common factors affecting the formation of crack consist of contacting shell with cooled steam, expansion and contraction movement of a turbine, insufficient insulation, stop valve spring force, internal pressure, and fluid flow momentum are assessed. The von Mises stresses caused by each factor have been determined. It has been attempted to identify the main cause of cracking by comparing the obtained stress concentration points with the real coordinates of the crack. The results of the simulation revealed that the expansion and contraction movements of the turbine were the main cause of fatigue and crack in the stop valve body. Given the key role of the stop valve in generating power of turbines, the findings of this simulation can help to design sensitive equipment more accurately.

COMPARISON OF ENERGY FLOW STREAM AND ISENTROPIC METHOD FOR STEAM TURBINE ENERGY ANALYSIS

In this paper, a comparison of two different methods for a steam turbine energy analysis is presented. A high-pressure steam turbine from a supercritical thermal power plant (HPT) was analysed at three different turbine loads using the energy flow stream (EFS) method and isentropic (IS) method. The EFS method is based on steam turbine input and output energy flow streams and on the real steam turbine produced power. The method is highly dependable on the steam mass flow rate lost through the turbine gland seals. The IS method is based on a comparison of turbine steam expansion processes. Observed energy analysis methods cannot be directly compared because they are based on different sources of steam turbine energy losses, so, an overall steam turbine energy analysis is presented. Unlike most steam turbines from the literature, the analysed HPT did not have the highest overall energy efficiency at a full load due to exceeding the water/steam critical pressure at the turbine inlet during such operation.

Optimization and analysis of exergy, economic, and environmental of a combined cycle power plant

In this study, a combined cycle power plant with a nominal capacity of 500 MW, including two gas turbine units and one steam turbine unit, is considered by a mathematical model. This study is carried out to optimize three objective functions of exergy efficiency, CO2 emission and produced power costs. This multi-objective optimization has been carried out by using the Non-Dominated Sorting Genetic Algorithm (NSGA-II). The results indicate that the efficiency of the combined cycle power plant depends on the design parameters including gas turbine input temperature, compressor pressure ratio, and pinch point temperature. Furthermore, any change occurring in these settings may lead to noticeable changes in objective functions, so that the efficiency of this power plant is increased after optimization by up to 8.12 %, and its heat rate is correspondingly reduced from 7233 (kJ/kWh) to 7023 (kJ/kWh). Similarly, exergy destruction in the total system shows a reduction by 7.23%.

Thermoeconomic analysis and optimization of a solar micro CCHP by using TLBO algorithm for domestic application

ABSTRACTIn the present study, a micro solar Combined Cooling, Heating and Power (CCHP) system based on Organic Rankine Cycle (ORC) is thermodynamically and exergoeconomically investigated. Adding a storage tank will lead to the sustainable supply of energy for summer and winter seasons. The model of conservation of energy, conservation of mass, and conservation of linear momentum are applied in order to energy analysis, while a model based on the first and the second laws of thermodynamics are used to exergy analysis. Determining the effective parameters of the system efficiency, including turbine input pressure, turbine inlet temperature, turbine output pressure, and evaporator temperature leads to improve and optimize the system performance. The Teaching–Learning-Based Optimization (TLBO), for the first time in this paper, is employed for both single-objective and multi-objective optimizations of the system for three working fluids (R123, R134a, and R245fa). The accuracy of the proposed model is validated by data presented in three different papers. For the summer season, the values of the energy efficiency, exergy efficiency, and cost rate for R123 working fluid are calculated as 24.81%, 9.94%, and 5383$/year, respectively. The implementation of the multi-objective optimization using TLBO for R123 working fluid improves 27.85% thermal efficiency, 27.66% exergy efficiency and reduces 9.90% of the system cost rate.

Development and performance analysis of a new solar tower and high temperature steam electrolyzer hybrid integrated plant

In this article, an extensive thermodynamic performance assessment for the useful products from the solar tower and high-temperature steam electrolyzer assisted multigeneration system is performed, and also its sustainability index is also investigated. The system under study is considered for multi-purposes such as power, heating, cooling, drying productions, and also hydrogen generation and liquefaction. In this combined plant occurs of seven sub-systems; the solar tower, gas turbine cycle, high temperature steam electrolyzer, dryer process, heat pump, and absorption cooling system with single effect. In addition, the energy and exergy performance, irreversibility and sustainability index of multigeneration system are examined according to several factors, such as environment temperature, gas turbine input pressure, solar radiation and pinch point temperature of HRSG. Results of thermodynamic and sustainability assessments show that the total energetic and exergetic efficiency of suggested paper are calculated as 60.14%, 58.37%, respectively. The solar tower sub-system has the highest irreversibility with 18775 kW among the multigeneration system constituents. Solar radiation and pinch point temperature of HRSG are the most critical determinants affecting the system energetic and exergetic performances, and also hydrogen production rate. In addition, it has been concluded that, the sustainability index of multigeneration suggested study has changed between 2.2 and 3.05.

Study on temperature measurement of gas turbine blade based on analysis of error caused by the reflected radiation and emission angle

Accurate measurement of gas turbine blade temperature is of great significance as far as blade health monitoring is concerned. An important method for measuring this temperature is the use of a radiation pyrometer. In this research, error of the pyrometer caused by reflected radiation from the surfaces surrounding the target and the emission angle of the target was analyzed. Important parameters for this analysis were the view factor between interacting surfaces, spectral directional emissivity, pyrometer operating wavelength and the surface temperature distribution on the blades and the vanes. The interacting surface of the rotor blade and the vane models used were discretized using triangular surface elements from which contour integral was used to calculate the view factor between the surface elements. Spectral directional emissivities were obtained from an experimental setup of Ni based alloy samples. A pyrometer operating wavelength of 1.6 μm was chosen. Computational fluid dynamics software was used to simulate the temperature distribution of the rotor blade and the guide vane based on the actual gas turbine input parameters. Results obtained in this analysis show that temperature error introduced by reflected radiation and emission angle ranges from −23 K to 49 K.

Thermodynamic analysis and assessment of a novel integrated geothermal energy-based system for hydrogen production and storage

In this paper, thermodynamic analysis and assessment of a novel geothermal energy based integrated system for power, hydrogen, oxygen, cooling, heat and hot water production are performed. This integrated process consists of (a) geothermal subsystem, (b) Kalina cycle, (c) single effect absorption cooling subsystem and (d) hydrogen generation and storage subsystems. The impacts of some design parameters, such as absorption chiller evaporator temperature, geothermal source temperature, turbine input pressure and pinch point temperature on the integrated system performance are investigated to achieve more efficient and more effective. Also, the impacts of reference temperature and geothermal water temperature on the integrated system performance are studied in detail. The energetic and exergetic efficiencies of the integrated system are then calculated as 42.59% and 48.24%, respectively.

Değişken Hızlı Rüzgâr Türbinlerinde Kanat Ucu Hız Oranı Tabanlı Maksimum Güç İzleme Denetimi; Kapsamlı Bir Tasarım

The most primitive control method of wind turbines used to generate electric energy from wind is the fixed speed control method. With this method, it is not possible that turbine input power is transferred to grid at maximum rate. For this reason, Maximum Power Tracking (MPT) schemes are proposed. In order to implement MPT, the propeller has to rotate at a different speed for every different wind speed. This situation has led MPT based systems to be called Variable Speed Wind Turbine (VSWT) systems. In VSWT systems, turbine input power can be transferred to grid at rates close to maximum power. When MPT based control of VSWT systems is the case, two important processes come into prominence. These are instantaneously determination and tracking of MPT point. In this study, using a Maximum Power Point Tracking (MPPT) method based on tip speed ratio, power available in wind is transferred into grid over a back to back converter at maximum rate via a VSWT system with permanent magnet synchronous generator (PMSG). Besides a physical wind turbine simulator is modelled and simulated. Results show that a time varying MPPT point is tracked with a high performance.

Development and experimental study of a small-scale compressed air radial inflow turbine for distributed power generation

With ever increasing demand on energy, disturbed power generation utilizing efficient technologies such as compressed air energy storage (CAES) and organic Rankine cycle (ORC) are receiving growing attention. Expander for such systems is a key component and its performance has substantial effects on overall system efficiency. This study addresses such component by proposing an effective and comprehensive methodology for developing a small-scale radial inflow turbine (RIT). The methodology consists of 1-D modelling, 3-D aerodynamic investigation and structural analysis, manufacturing with pioneering technique and experimental testing for validation. The proposed 1-D modelling was very effective in determining the primary geometry and performance of turbine based on parametric studies of turbine input design variables. However with CFD analysis, it was shown that more efficient turbine geometry can be achieved that not only provides more realistic turbine performance by capturing the 3-D fluid flow behaviour but also improves turbine efficiency with the aid of parametric studies of turbine geometry parameters. Turbine efficiency was improved from 81.3% obtained from 1-D modelling to 84.5% obtained by CFD. Accuracy of the CFD model was assessed by conducting experiments on the RIT manufactured with stereolithography technique. The CFD model can predict turbine efficiency and power with accuracy of ±16% and ±13% respectively for a wide range of tested operating conditions. Such results highlights the effectiveness of the proposed methodology and the CFD model can be used as benchmarking model for analyses of small-scale RITs. Besides, it was shown that for such applications, the novel manufacturing technique and employed material are very effective for producing prototypes that assist design decisions and validation of CFD model with reasonable accuracy at reasonable cost and in timely manner.

Analysis of Nigerian Electricity Generation Multi Year Tariff Order Pricing Model

The Multi Year Tariff Order (MYTO) is the Nigerian Electricity Regulatory Commission (NERC) pricing framework for determining the Nigerian Electricity Supply Industry (NESI) pricing model. One of the objectives of the NERC’s MYTO pricing model is to ensure regulated electricity end user tariff without compromising return on investment. Achieving this objective is imperative to attract investors in the growing Nigerian electricity market. However, NESI has hitherto been faced with challenges ranging from its inability to provide sufficient power to its customers to not being viable enough to provide return on capital invested. In this paper, sensitivity analysis of power plant operation and performance parameters on the cost of electricity (CoE) generation using MYTO (power generation) pricing model were evaluated. Thermodynamic modeling and simulation of an open cycle gas turbine (OCGT) was carried out to augment scarce data on power plant performance and operation in Nigeria. Sensitivity analysis was carried out using probabilistic method based on Monte Carlo simulation (MCS) implemented in commercial software (@ Risk®). The result highlighted sensitivity of the model input parameters to cost of electricity generation based on technical and financial assumptions of MYTO model. Seven most influential parameters affecting generation cost were identified. These parameters and their correlation coefficients are given as: 1) foreign exchange rate, 0.76; 2) cost of fuel, 0.51; 3) thermal efficiency, -0.23; 4) variable operation and maintenance cost, 0.22; 5) fixed operating and maintenance cost, -0.03; 6) capacity factor, -0.02; and 7) average capacity degradation, 0.01. Based on the gas turbine engine and input parameter distributions statistics for this study, the generation cost lies between 9.84 to 15.45 N/kWh and the probabilities of CoE within these values were established.

Thermodynamic assessment of CO2 to carbon nanofiber transformation for carbon sequestration in a combined cycle gas or a coal power plant

Molten carbonate electrolyzers offer a pathway to capture emitted CO2 from the flue gas of the power plants and transform this greenhouse gas emission at low energy and high yield instead into a specific, value added, hollow carbon nanofiber product, carbon nanotubes. The present day value of the carbon nanotubes product is ∼10,000 that of proposed, or in place, current carbon tax costs of $30 per ton, strongly incentivizing carbon dioxide removal. The recent progress in high-temperature molten carbonate electrolysis systems for carbon dioxide utilization and the impact these advances have on developing a CO2-free fossil fuel power plant for electricity generation is presented. A thermodynamic model analysis is presented for a molten Li2CO3 electrolysis system incorporated within a combined cycle (CC) natural gas power plant to produce carbon nanofibers (CNF) and oxygen. Such a CC CNF plant system is shown to require 219kJ to convert one mole of CO2 to carbon, and generates electricity at higher efficiency due to pure oxygen looped back to the gas turbine input from the CO2 splitting, with the added advantages that (i) the CC CNF plant emits no CO2 and (ii) all CO2 is converted to value added carbon nanotubes useful for strong, lightweight construction, batteries and nanoelectronics. Converting to power and ton units, per metric ton of methane fuel consumed the CC CNF plant is thermodynamically assessed to produce 8350kWh of electricity and 0.75 ton of CNT and emits no CO2, while the CC plant produces 9090kWh of electricity and emits 2.74 ton CO2. The required energy balance for a carbon nanotube production from an analogous coal power plant consumes a larger fraction of the coal energy, and encourages co-generation with renewable electric energy.

Thermodynamics Analysis and Optimization of Abadan Combined Cycle Power Plant

Background/Objectives: The welfare and comfort of people in the world is directly related to consuming energy and its economic supply, which depends on quantity of energy resources. This has been turned into an important challenge with respect to rapid growth at level of request for energy in the world. Methods/Statistical analysis: In this multiobjective optimization that has been carried out by Non-Dominated Sorting Genetic Algorithm (NSGA-II), two objective functions of exergy efficiency and produced power costs composing of the cost of injected fuel into combustion chamber and duct burner as well as exergy loss cost and investment cost have been studied. Findings: The efficiency of Abadan combined cycle power plant depends on design parameters including gas turbine input temperature, compressor pressure ratio, and pinch point temperature and any change occurring in these parameters may lead to noticeable change in objective functions, so that the efficiency of this power plant is increased after optimization up to 7.12 % and heat rate is correspondingly reduced from 7503 (kJ/kWh) to 7149 (kJ/kWh). Similarly, exergy destruction in total system shows 8.37 reduction. Applications/Improvements: In this research Abadan combined cycle power plant has been perfectly modeled in terms of thermodynamics and the given results were compared with output data from Thermo-Flow Software in order to ensure the validity of the modeling code.

Rotordynamic Performance Measurements of An Oil-Free Turbocharger Supported on Gas Foil Bearings and Their Comparisons to Floating Ring Bearings

This paper presents the rotordynamic performance measurement of oil-free turbocharger (TC) supported on gas foil bearings (GFBs) for 2 liter class diesel vehicles and comparison to floating ring bearings (FRBs). Oil-free TC was designed and developed via the rotordynamic analyses using dynamic force coefficients from GFB analyses. The rotordynamics and performance of the oil-free TC was measured up to 85 krpm while being driven by a diesel vehicle engine, and compared to a commercial oil-lubricated TC supported on FRBs. The test results showed that the GFBs increased the rotor speed by ~ 20% at engine speeds of 1,500 rpm and 1,750 rpm, yielding the reduction of turbine input energy by more than 400 W. Incidentally, an external shock test on the oil-free TC casing was conducted at the rotor speed of 60 krpm, and showed a good capability of vibration damping due to the well-known dry friction mechanism of the GFBs.

Power quality analysis of hybrid renewable energy system

An hybrid renewable energy sources consisting of solar photovoltaic, wind energy system, and a microhydro system is proposed in this paper. This system is suitable for supplying electricity to isolated locations or remote villages far from the grid supply. The solar photovoltaic system is modeled with two power converters, the first one being a DC-DC converter along with an maximum power point tracking to achieve a regulated DC output voltage and the second one being a DC-AC converter to obtain AC output. The wind energy system is modeled with a wind-turbine prime mover with varying wind speed and fixed pitch angle to drive an self excited induction generator (SEIG). Owing to inherent drooping characteristics of the SEIG, a closed loop turbine input system is incorporated. The microhydro system is modeled with a constant input power to drive an SEIG. The three different sources are integrated through an AC bus and the proposed hybrid system is supplied to R, R-L, and induction motor loads. A static compensator is proposed to improve the load voltage and current profiles; it also mitigates the harmonic contents of the voltage and current. The static synchronous compensator is realized by means of a three-phase IGBT-based current-controlled voltage source inverter with a self-supporting DC bus. The complete system is modeled and simulated using Matlab/Simulink. The simulation results obtained illustrate the feasibility of the proposed system and are found to be satisfactory.

Optimal Intelligent Control for Wind Turbulence Rejection in WECS Using ANNs and Genetic Fuzzy Approach

One of the disadvantages in Connection of wind energy conversion systems (WECSs) to transmission networks is plentiful turbulence of wind speed. Therefore effects of this problem must be controlled. �owadays, pitch-controlled WECSs are increasingly used for variable speed and pitch wind turbines. Megawatt class wind turbines generally turn at variable speed in wind farm. Thus turbine operation must be controlled in order to maximize the conversion efficiency below rated power and reduce loading on the drive-train. Due to random and non-linear nature of the wind turbulence and the ability of Multi-Layer Perceptron (MLP) and Radial Basis Function (RBF) Artificialeuraletworks (A��s) in the modeling and control of this turbulence, in this study, widespread changes of wind have been perused using MLP and RBF artificial ��s. In addition in this study, a new genetic fuzzy system has been successfully applied to identify disturbance wind in turbine input. Thus output power has been regulated in optimal and nominal range by pitch angle regulation. Consequently, our proposed approaches have regulated output aerodynamic power and torque in the nominal range.

Studies on the Shore-Fixed Air Chamber for Wave Power Generation. Pressure and Flow Direction Control for a Turbine with a Swaying Valve.

The air chamber system is a kind of method for transformation from wave energy to mechanical energy. In this system, wave energy operates periodically in the wave power generation plant. In order to improve this system, we propose a new technology with one-way flow and restriction of turbine input. The former is applicable to an impulse turbine, and the latter saves the excess power from the air chamber. In this system, the air duct has a bypath with a turbine. Pressure and flow direction are controlled with only one swing plate valve in the air duct. This paper describes both experimental results at a site of sea-side, and the analytical result of the plant performance.

Integrated control of a nonlinear turboalternator model under fault conditions

The integrated control of a nonlinear turboalternator model interconnected with a grid system and supplying a local asynchronous-type load is studied. The alternator equations incorporate the effects of transient saliency, positive-sequence damping, field-flux-linkage variation, machine saturation and excitation control. Turbine input power is controlled by a conventional governor representation with facilities for speed resetting. Transient performance of the system operating under external-load-change and short-circuit-fault conditions with line switching is studied by digital simulation, using conventional and linear-model control of the nonlinear system. Integrated control of governor-valve and alternator-field excitation is related to the optimisation of a sequence of piecewise-linearised models associated with quadratic cost functions. Improved machine-voltage and speed performance is obtained with extended stability limits using a limited set of linear models, compared with the use of independent conventional controllers. The transient control of a quadrature-axis rotor field winding in the synchronous machine is investigated and is found to be effective in improving overall performance and in extending the synchronous-machine and induction-motor stability limits.