Thermodynamic Performance Analyses of Mixed Gas-Steam Cycle (1): Performance Prediction Method

Author(s):  
Kirk Hanawa

There are various papers relevant to the improvement ideas of gas turbine cycles, which in general discuss only optimum one-point cycle analysis.*1,*2,*6 It is, accordingly, unclear whether such improvement concepts can be applied into existing gas turbines or not. It might be difficult to incorporate such ideas, in the case of yielding significant changes for operation modes. And it may be essential to assess improvement ideas, from view points of applicability to existing gas turbine models.*3 This paper introduces the performance analysis method of simplified small perturbation procedure, showing thermodynamic behaviors based upon the component characteristics, and resultant influences due to settled operation parameters, like ambient temperature & pressure, turbine inlet temperature, etc. The established method might be used as a rule of thumb for the performance prediction when introducing water and/or steam injection into GTs, where operational parameters’ changes are defined under multi-linear differential equations. This is easy to compile in the computer as Lotus 1-2-3 or Exel to evaluate whether every parameter is within the limit or not, offering very helpful performance evaluation tool for the conceptual design stage.

Author(s):  
Xingxing Ji ◽  
Chunwei Gu ◽  
Yin Song ◽  
Weihong Xie

Performance prediction method of the modern gas turbine is an important tool for the engine design and performance analysis. This paper integrates a hybrid cooling model to the previous research of gas turbine performance prediction method which is applied to predict the multi-shaft gas turbine performance. The cooling model, combined with the semi-empirical model and analytical model, had been originally proposed for the investigation of turbine convective cooling or film cooling performance. The aim of the work is to apply the hybrid model to effectively estimate the coolant requirement in the gas turbine performance prediction, therefore to improve the reliability of the analysis in the innovative gas turbine cycle. The analysis involved a three-shaft gas turbine. Experiments were carried out on the engine, and the effectiveness of the prediction method is validated by the experiment. Consequently detailed performance characteristic of the engine is investigated under different stagger angles of the variable-angle nozzle, revealing how the stagger angle of the variable-angle nozzle and the turbine inlet temperature affect the gas turbine performance. The analysis is considered valuable for the engine operation and components optimization.


Author(s):  
Keisuke Makino ◽  
Ken-Ichi Mizuno ◽  
Toru Shimamori

NGK Spark Plug Co., Ltd. has been developing various silicon nitride materials, and the technology for fabricating components for ceramic gas turbines (CGT) using theses materials. We are supplying silicon nitride material components for the project to develop 300 kW class CGT for co-generation in Japan. EC-152 was developed for components that require high strength at high temperature, such as turbine blades and turbine nozzles. In order to adapt the increasing of the turbine inlet temperature (TIT) up to 1,350 °C in accordance with the project goals, we developed two silicon nitride materials with further unproved properties: ST-1 and ST-2. ST-1 has a higher strength than EC-152 and is suitable for first stage turbine blades and power turbine blades. ST-2 has higher oxidation resistance than EC-152 and is suitable for power turbine nozzles. In this paper, we report on the properties of these materials, and present the results of evaluations of these materials when they are actually used for CGT components such as first stage turbine blades and power turbine nozzles.


Author(s):  
Matti Malkamäki ◽  
Ahti Jaatinen-Värri ◽  
Antti Uusitalo ◽  
Aki Grönman ◽  
Juha Honkatukia ◽  
...  

Decentralized electricity and heat production is a rising trend in small-scale industry. There is a tendency towards more distributed power generation. The decentralized power generation is also pushed forward by the policymakers. Reciprocating engines and gas turbines have an essential role in the global decentralized energy markets and improvements in their electrical efficiency have a substantial impact from the environmental and economic viewpoints. This paper introduces an intercooled and recuperated three stage, three-shaft gas turbine concept in 850 kW electric output range. The gas turbine is optimized for a realistic combination of the turbomachinery efficiencies, the turbine inlet temperature, the compressor specific speeds, the recuperation rate and the pressure ratio. The new gas turbine design is a natural development of the earlier two-spool gas turbine construction and it competes with the efficiencies achieved both with similar size reciprocating engines and large industrial gas turbines used in heat and power generation all over the world and manufactured in large production series. This paper presents a small-scale gas turbine process, which has a simulated electrical efficiency of 48% as well as thermal efficiency of 51% and can compete with reciprocating engines in terms of electrical efficiency at nominal and partial load conditions.


Author(s):  
Daniel E. Caguiat

The Naval Surface Warfare Center, Carderock Division (NSWCCD) Gas Turbine Emerging Technologies Code 9334 was tasked by NSWCCD Shipboard Energy Office Code 859 to research and evaluate fouling resistant compressor coatings for Rolls Royce Allison 501-K Series gas turbines. The objective of these tests was to investigate the feasibility of reducing the rate of compressor fouling degradation and associated rate of specific fuel consumption (SFC) increase through the application of anti-fouling coatings. Code 9334 conducted a market investigation and selected coatings that best fit the test objective. The coatings selected were Sermalon for compressor stages 1 and 2 and Sermaflow S4000 for the remaining 12 compressor stages. Both coatings are manufactured by Sermatech International, are intended to substantially decrease blade surface roughness, have inert top layers, and contain an anti-corrosive aluminum-ceramic base coat. Sermalon contains a Polytetrafluoroethylene (PTFE) topcoat, a substance similar to Teflon, for added fouling resistance. Tests were conducted at the Philadelphia Land Based Engineering Site (LBES). Testing was first performed on the existing LBES 501-K17 gas turbine, which had a non-coated compressor. The compressor was then replaced by a coated compressor and the test was repeated. The test plan consisted of injecting a known amount of salt solution into the gas turbine inlet while gathering compressor performance degradation and fuel economy data for 0, 500, 1000, and 1250 KW generator load levels. This method facilitated a direct comparison of compressor degradation trends for the coated and non-coated compressors operating with the same turbine section, thereby reducing the number of variables involved. The collected data for turbine inlet, temperature, compressor efficiency, and fuel consumption were plotted as a percentage of the baseline conditions for each compressor. The results of each plot show a decrease in the rates of compressor degradation and SFC increase for the coated compressor compared to the non-coated compressor. Overall test results show that it is feasible to utilize anti-fouling compressor coatings to reduce the rate of specific fuel consumption increase associated with compressor performance degradation.


Author(s):  
Thomas Palmé ◽  
Francois Liard ◽  
Dan Cameron

Due to their complex physics, accurate modeling of modern heavy duty gas turbines can be both challenging and time consuming. For online performance monitoring, the purpose of modeling is to predict operational parameters to assess the current performance and identify any possible deviation between the model’s expected performance parameters and the actual performance. In this paper, a method is presented to tune a physical model to a specific gas turbine by applying a data-driven approach to correct for the differences between the real gas turbine operation and the performance model prediction of the same. The first step in this process is to generate a surrogate model of the 1st principle performance model through the use of a neural network. A second “correction model” is then developed from selected operational data to correct the differences between the surrogate model and the real gas turbine. This corrects for the inaccuracies between the performance model and the real operation. The methodology is described and the results from its application to a heavy duty gas turbine are presented in this paper.


2009 ◽  
Vol 13 (4) ◽  
pp. 41-48
Author(s):  
Zheshu Ma ◽  
Zhenhuan Zhu

Indirectly or externally-fired gas-turbines (IFGT or EFGT) are novel technology under development for small and medium scale combined power and heat supplies in combination with micro gas turbine technologies mainly for the utilization of the waste heat from the turbine in a recuperative process and the possibility of burning biomass or 'dirty' fuel by employing a high temperature heat exchanger to avoid the combustion gases passing through the turbine. In this paper, by assuming that all fluid friction losses in the compressor and turbine are quantified by a corresponding isentropic efficiency and all global irreversibilities in the high temperature heat exchanger are taken into account by an effective efficiency, a one dimensional model including power output and cycle efficiency formulation is derived for a class of real IFGT cycles. To illustrate and analyze the effect of operational parameters on IFGT efficiency, detailed numerical analysis and figures are produced. The results summarized by figures show that IFGT cycles are most efficient under low compression ratio ranges (3.0-6.0) and fit for low power output circumstances integrating with micro gas turbine technology. The model derived can be used to analyze and forecast performance of real IFGT configurations.


2021 ◽  
Author(s):  
Dan Liu ◽  
Shisheng Zhong ◽  
Lin Lin ◽  
Minghang Zhao ◽  
Xiangzhao Xia ◽  
...  

2021 ◽  
Author(s):  
Takashi Nishiumi ◽  
Hirofumi Ohara ◽  
Kotaro Miyauchi ◽  
Sosuke Nakamura ◽  
Toshishige Ai ◽  
...  

Abstract In recent years, MHPS achieved a NET M501J gas turbine combined cycle (GTCC) efficiency in excess of 62% operating at 1,600°C, while maintaining NOx under 25ppm. Taking advantage of our gas turbine combustion design, development and operational experience, retrofits of earlier generation gas turbines have been successfully applied and will be described in this paper. One example of the latest J-Series technologies, a conventional pilot nozzle was changed to a premix type pilot nozzle for low emission. The technology was retrofitted to the existing F-Series gas turbines, which resulted in emission rates of lower than 9ppm NOx(15%O2) while maintaining the same Turbine Inlet Temperature (TIT: Average Gas Temperature at the exit of the transition piece). After performing retrofitting design, high pressure rig tests, the field test prior to commercial operation was conducted on January 2019. This paper describes the Ultra-Low NOx combustor design features, retrofit design, high pressure rig test and verification test results of the upgraded M501F gas turbine. In addition, it describes another upgrade of turbine to improve efficiency and of combustion control system to achieve low emissions. Furthermore it describes the trouble-free upgrade of seven (7) units, which was completed by utilizing MHPS integration capabilities, including handling all the design, construction and service work of the main equipment, plant and control systems.


Author(s):  
Uyioghosa Igie ◽  
Marco Abbondanza ◽  
Artur Szymański ◽  
Theoklis Nikolaidis

Industrial gas turbines are now required to operate more flexibly as a result of incentives and priorities given to renewable forms of energy. This study considers the extraction of compressed air from the gas turbine; it is implemented to store heat energy at periods of a surplus power supply and the reinjection at peak demand. Using an in-house engine performance simulation code, extractions and injections are investigated for a range of flows and for varied rear stage bleeding locations. Inter-stage bleeding is seen to unload the stage of extraction towards choke, while loading the subsequent stages, pushing them towards stall. Extracting after the last stage is shown to be appropriate for a wider range of flows: up to 15% of the compressor inlet flow. Injecting in this location at high flows pushes the closest stage towards stall. The same effect is observed in all the stages but to a lesser magnitude. Up to 17.5% injection seems allowable before compressor stalls; however, a more conservative estimate is expected with higher fidelity models. The study also shows an increase in performance with a rise in flow injection. Varying the design stage pressure ratio distribution brought about an improvement in the stall margin utilized, only for high extraction.


Author(s):  
Takayuki Matsunuma ◽  
Hiro Yoshida ◽  
Norihiko Iki ◽  
Takumi Ebara ◽  
Satoshi Sodeoka ◽  
...  

A series of operation tests of a ceramic micro gas turbine has been successfully carried out. The baseline machine is a small single-shaft turbojet engine (J-850, Sophia Precision Corp.) with a centrifugal compressor, an annular type combustor, and a radial turbine. As a first step, an Inconel 713C alloy turbine rotor of 55 mm in diameter was replaced with a ceramic rotor (SN-235, Kyocera Corporation). A running test was conducted at rotational speeds of up to 140,000 rpm in atmospheric air. At this rotor speed, the compression pressure ratio and the thrust were 3 and 100 N, respectively. The total energy level (enthalpy and kinetic energy) of the exhaust gas jet was 240 kW. If, for example, it is assumed that 10% of the total power of the exhaust jet gas was converted into electricity, the present system would correspond to a generator with 24 kW output power. The measured turbine outlet temperature was 950°C (1,740°F) and the turbine inlet temperature was estimated to be 1,280°C (2,340°F). Although the ceramic rotor showed no evidence of degradation, the Inconel nozzle immediately in front of the turbine rotor partially melted in this rotor condition. As a second step, the Inconel turbine nozzle and casing were replaced with ceramic parts (SN-01, Ohtsuka Ceramics Inc.). The ceramic nozzle and case were supported by metal parts. Through tests with the ceramic nozzle, it became evident that one of the key technologies for the development of ceramic gas turbines is the design of the interface between the ceramic components and the metallic components, because the difference between the coefficients of linear thermal expansion of the ceramic and metal produces large thermal stress at their interface in the high-temperature condition. A buffer material made of alumina fiber was therefore introduced at the interface between the ceramic and metal.


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