Micro gas turbine

A heavy duty gas turbine rotor operates in a highly nonlinear environment. It is often taken to thermal transients and over-speed events. The source of excitations often excites the blades during in-service life. Various stresses generated in the turbine rotor are not only due to centrifugal forces but also due to wake forces generated during the flow through airfoil, which later generates fatigue, Vibratory and creep loads. Structural failures may occur due to various uncertainties involved in the operation of gas turbines such as speed loads, over-speeding and component manufacturing deviations. If catastrophic rotor failures occur, they commonly result in lengthy forced outages and severe economic penalties to the affected utilities. In the present work, assessment of structural integrity of Integrated bladed rotor assessment is accomplished through conduction of an Finite Element analysis blended with classical theories. The structural analysis results of IBR is compared with Bladed Disc assembly to highlight the effect of Contact at Blade Butting zone on frequency response along with Integrated Model(IBR) for a given flow conditions and airfoil. In addition to evaluation of structural strength in the rotor disc components, failures due to vibrations are also quite apparent in the Gas turbine blades. An attempt is made to investigate the resonance points at operating speeds, disk mode participations if any and retrieve excitation frequency modes, Campbell, SAFE (Singh's Advanced Frequency Evaluation Diagram) are generated and analyzed to evaluate the separation margins for Blade and disk integrity.

Microturbines (MGTs) are power generation devices showing very interesting performance in terms of low environmental impact, high-grade waste heat and very low maintenance cost. One of the main issues that affect the output of MGTs is their strong sensibility to inlet air temperature. Both in literature and in practical applications, several solutions have been applied to control the inlet air conditions and reduce the sensibility of this kind of machines to ambient conditions. One of the most interesting technology is the refrigerating vapour compression technique. This solution has already been used for medium/large GTs, but there are very limited inlet air cooling applications on MGTs and few experimental data are documented. This paper describes a test bench that has been designed to apply the direct vapour expansion technique to a 100 kWe MGT and reports the power and efficiency augmentation of the machine when operating in hot summer days.

The chiller was designed to treat the MGT’s air flow rate under specific working conditions and cool the inlet air temperature down to 15 °C. Thanks to the reduction of the inlet air temperature, the MGT showed a benefit in terms of electric power gain up to 8% with respect to the nominal power output in ISO conditions while the electric efficiency increased by 1.5%. Results indicate that an almost linear trend can be obtained both in the electric power increase and in the electric efficiency increase as a function of the inlet air temperature when the chiller operates under nominal working conditions. When the IAC device operates at a higher temperature or a higher humidity than the design one, the gain is limited; in some working conditions with high relative humidity, most of the beneficial effect can even be lost.

This study presents an analytical method that can be used to enhance the power production rate and the energy-saving at wastewater treatment plants. The digester used at wastewater treatment plants produces digester gas by anaerobic digestion, with which biofuel production can be achieved. Biofuels can be used to meet some of the energy requirements of the wastewater treatment facility through Combined Heat and Power (CHP) gas engines (co-generation). Using Micro Gas Turbine (MGT), a CHP technology can be introduced in Wastewater Treatment Plants (WWTPs). The combination of MGTs and absorption chillers is a promising technology as it produces electricity, heating, and cooling simultaneously. The study demonstrated how the waste heat of MGTs could be used to drive absorption chillers. In this analytical study, a detailed technical and economic analysis is provided on the tri-generation system, i.e., the integration of MGTs and absorption chillers driven by waste digester gas of the w...

Gas turbines are a viable and secure option both economically and environmentally for combined heat and power generation. Process modelling of a micro gas turbine for CO2 injection and exhaust gas recirculation (EGR) is performed. Further, this study is extended to assess the effect of the CO2 injection on the pilot-scale CO2 capture plant integrated with a micro gas turbine. In addition, the impact of the EGR on the thermodynamic propertiesof the fluid at different locations of the micro gas turbine is also evaluated. The micro gas turbine and CO2 injection models are validated against the set of experimental data and the performance analysis of the EGR cycle results in CO2 enhancement to 5.04 mol% and 3.5 mol%, respectively. The increased CO2 concentration in the flue gas, results in the specific reboiler duty decrease by 20.5% for pilot-scale CO2 capture plant at 90% CO2 capture rate for 30 wt.% MEA aqueous solution. The process system analysis for the validated models results in a much better comprehension of the impact of the CO2 enhancement on the process behaviour.

This paper describes a test bench that has been designed to evaluate the effect of inlet air cooling (IAC) techniques on the improvement of the performance of a 100 kWe micro gas turbine (MGT). In particular, two inlet air cooling techniques were tested: the fogging and the direct expansion. The results of the experimental analysis show that with the fogging technology the electric power augmentation ranges between 4% and 11% referred to the machine's ISO condition output depending on the initial conditions of the ambient air humidity. During the tests with direct expansion technology, a net electric power augmentation up to 8% referred to the machine's ISO condition output was registered; also the net electric efficiency gain showed a peak of 1.5%.

The use of renewable energies, mainly wind and photovoltaic, are sources of generation that have spread worldwide by micro-grids. In places where the implementation of electric grids is inaccessible or economically not feasible, the installation of wind micro-turbines and photovoltaic systems for electricity generation and water pumping systems has been implemented; however, renewable energies have not yet been used in some rural areas due to the lack of studies and initiatives of their own. In the present study, in situ measurements have been used to evaluate the wind potential in rural town and the application for micro-turbine. Through the Weibull Distribution, an analysis of the wind energy potential available in the area has been carried out incorporating commercial wind micro-turbines and energy cost analysis. The favorable wind levels and the nominal speed values of commercial turbines have allowed obtaining the capacity factor values and energy costs, which allowed determining the feasibility of the installation of wind micro-turbines to provide electric energy to the habitants of this town.

Micro gas turbines are an auspicious technology for power generation because of their small size, low pollution, low maintenance, high reliability and natural fuel used. Recuperator is vital requirement in micro gas turbine unit for improve the efficiency of micro turbine unit. Heat transfer and pressure drop characteristics are important for designing an efficient recuperator. Recuperators preheat compressed air by transfer heat from exhaust gas of turbines, thus reducing fuel consumption and improving the thermal efficiency of micro gas turbine unit from 16-20% to 30%. The fundamental principles for optimization design of PSR are light weight, low pressure loss and high heat-transfer between exhaust gas to compressed air. There is many type of recuperator used in micro gas turbine like Annular CWPS recuperator , recuperator with involute-profile element , honey well , swiss-Roll etc. In this review paper is doing study of Heat transfer and pressure drop characteristics of many types recuperator.

The aim of this work is the experimental analysis of a primary-surface recuperator, operating in a 100 kW micro gas turbine, as in a standard recuperated cycle. These tests, performed in both steady-state and transient conditions, have been carried out using the micro gas turbine test rig, developed by the Thermochemical Power Group at the University of Genova, Italy. Even if this facility has mainly been designed for hybrid system emulations, it is possible to exploit the plant for component tests, such as experimental studies on recuperators. The valves installed in the rig make it possible to operate the plant in the standard recuperated configuration, and the facility has been equipped with new probes essential for this kind of tests. A wide-ranging analysis of the recuperator performance has been carried out with the machine, operating in stand-alone configuration, or connected to the electrical grid, to test different control strategy influences. Particular attention has been ...

The report on X International Scientific-Practical Conference "Engines and vehicle components: R&D and production, operation and service maintenance". 27-28 June 2017 Protvino, Moscow Region, Russia.
The report gives a brief description of the development of computer software for modeling of wear in the field of radial clearances of small-sized turbomachines when operating with dusty air. A brief description of experimental models intended for verification and testing of the software is presented. [in Russian]