Prediction and Mitigation Strategies for Compressor Instabilities due to Large Pressurized Volumes in Micro Gas Turbine Systems

2021 ◽  
Author(s):  
Thomas Krummrein ◽  
Martin Henke ◽  
Timo Lingstädt ◽  
Martina Hohloch ◽  
Peter Kutne
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Flow Instability ◽  
Measurement Data ◽  
Mitigation Strategies ◽  
Mathematical Explanation ◽  
Shaft Speed ◽  
Micro Gas Turbine ◽  
The Impact

Abstract Micro gas turbines are a versatile platform for advanced cycle concepts. In these novel cycles, basic micro gas turbine components — compressor, turbine, combustor and recuperator — are coupled with various other technologies to achieve higher efficiency and flexibility. Examples are hybrid power plants integrating pressurized fuel cells, solar receivers or thermal storages. Characteristically, such complex cycles contain vast pressurized gas volumes between compressor and turbine, many times larger than those contained in conventional micro gas turbines. In fast deceleration maneuvers the rotational speed of the compressor drops rapidly. However, the pressure decrease is delayed due to the large amount of gas contained in the volumes. Ultimately, this can lead to compressor flow instability or surge. To predict and mitigate such instabilities, not only the compressor surge limit must be known, but also the dynamic dependencies between shaft speed deceleration, pressure and flow changes within the system. Since appropriate experiments may damage the system, investigations with numerical simulations are crucial. The investigation begins with a mathematical explanation of the relevant mechanisms, based on a simplified analytical model. Subsequently, the DLR in-house simulation program TMTSyS (Transient Modular Turbo-System Simulator) is used to investigate the impact of transient maneuvers on a micro gas turbine test rig containing a large pressurized gas volume in detail. After the relevant aspects of the simulation model are validated against measurement data, it is shown that the occurrence of compressor instabilities induced by fast deceleration can be predicted with the simulator. It is also shown that the simulation tool enables these predictions using only measurement data of non-critical maneuvers. Hence, mitigation strategies are derived that allow to estimate save shaft speed deceleration rate limits based on non-critical performance measurements.

Assessment of the Potential of Combined Micro Gas Turbine and High Temperature Fuel Cell Systems

2002 ◽  
Author(s):  
Dieter Bohn ◽  
Nathalie Po¨ppe ◽  
Joachim Lepers
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Advanced Materials ◽  
Cell Systems ◽  
Micro Gas Turbine ◽  
Technological Assessment

The present paper reports a detailed technological assessment of two concepts of integrated micro gas turbine and high temperature (SOFC) fuel cell systems. The first concept is the coupling of micro gas turbines and fuel cells with heat exchangers, maximising availability of each component by the option for easy stand-alone operation. The second concept considers a direct coupling of both components and a pressurised operation of the fuel cell, yielding additional efficiency augmentation. Based on state-of-the-art technology of micro gas turbines and solid oxide fuel cells, the paper analyses effects of advanced cycle parameters based on future material improvements on the performance of 300–400 kW combined micro gas turbine and fuel cell power plants. Results show a major potential for future increase of net efficiencies of such power plants utilising advanced materials yet to be developed. For small sized plants under consideration, potential net efficiencies around 70% were determined. This implies possible power-to-heat-ratios around 9.1 being a basis for efficient utilisation of this technology in decentralised CHP applications.

On the Shaft Speed Selection of Parallel Hybrid Aero Engines

2021 ◽  
Author(s):  
Michael Sielemann ◽  
Jesse Gohl ◽  
Xin Zhao ◽  
Konstantinos Kyprianidis ◽  
Giorgio Valente ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Integrated Design ◽  
Low Pressure ◽  
Electrical Machine ◽  
Shaft Speed ◽  
Trade Off ◽  
Parallel Hybrid ◽  
Rules Of Thumb ◽  
The Impact

Abstract The boosted turbo fan or parallel hybrid is a promising means to reduce fuel consumption of gas turbines on aircraft. With an electric drive on the low-pressure spool of the gas turbine, it requires a trade-off between the characteristics of the gas turbine and the electric power sub-systems. Reducing specific thrust at a given thrust requirement results in a larger fan with a lower pressure ratio. This leads to improved propulsive efficiency but at the expense of increased weight and nacelle drag. At a given design relative tip Mach number, increasing fan size and hence tip diameter means the fan shaft speed will need to be reduced. This will, according to occasionally quoted ‘rules of thumb’, make the directly coupled electrical drive more efficient but heavier. The objective of this paper is to expose some key aspects of this trade-off in terms of efficiency and weight, and relate them to these guidelines. The paper applies sophisticated methodology in both addressed domains. For the gas turbine, multi-point design is used. Here, established synthesis matching schemes focusing on gas turbine performance parameters are extended with parameters from the sizing and weight estimation such as diameters and tip speeds. For the electrical machine, fully analytical sizing capturing the impact of cooling supply is used. The paper reports estimated gas path and machine geometries. It gives an understanding of the interactions between both sub-systems and allows concluding which low pressure spool speed gives the best instantaneous performance. It largely confirms the quoted rules of thumb but exposes that the factors affecting machine efficiency are more involved than implied for an integrated design.

Micro Gas-Turbine Design for Small-Scale Hybrid Solar Power Plants

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Lukas Aichmayer ◽  
James Spelling ◽  
Björn Laumert ◽  
Torsten Fransson
Keyword(s):  
Pressure Drop ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Small Scale ◽  
Receiver Design ◽  
Low Carbon ◽  
Micro Gas Turbine ◽  
Solar Power Plants ◽  
Electricity Costs

Hybrid solar micro gas-turbines are a promising technology for supplying controllable low-carbon electricity in off-grid regions. A thermoeconomic model of three different hybrid micro gas-turbine power plant layouts has been developed, allowing their environmental and economic performance to be analyzed. In terms of receiver design, it was shown that the pressure drop is a key criterion. However, for recuperated layouts, the combined pressure drop of the recuperator and receiver is more important. In terms of both electricity costs and carbon emissions, the internally-fired recuperated micro gas-turbine was shown to be the most promising solution of the three configurations evaluated. Compared to competing diesel generators, the electricity costs from hybrid solar units are between 10% and 43% lower, while specific CO2 emissions are reduced by 20–35%.

Micro Gas-Turbine Design for Small-Scale Hybrid Solar Power Plants

2013 ◽  
Author(s):  
Lukas Aichmayer ◽  
James Spelling ◽  
Björn Laumert ◽  
Torsten Fransson
Keyword(s):  
Pressure Drop ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Small Scale ◽  
Receiver Design ◽  
Low Carbon ◽  
Micro Gas Turbine ◽  
Solar Power Plants ◽  
Electricity Costs

Hybrid solar micro gas-turbines are a promising technology for supplying controllable low-carbon electricity in off-grid regions. A thermoeconomic model of three different hybrid micro gas-turbine power plant layouts has been developed, allowing their environmental and economic performance to be analyzed. In terms of receiver design, it was shown that the pressure drop is a key criterion. However, for recuperated layouts the combined pressure drop of the recuperator and receiver is more important. The internally-fired recuperated micro gas-turbine was shown to be the most promising solution of the three configurations evaluated, in terms of both electricity costs and carbon emissions. Compared to competing diesel generators, the electricity costs from hybrid solar units are between 10% and 43% lower, while specific CO2 emissions are reduced by 20–35%.

Solar Desalination Based on Micro Gas Turbines Driven by Parabolic Dish Collectors

2019 ◽  
Author(s):  
David Sánchez ◽  
Miguel Rollán ◽  
Lourdes García-Rodríguez ◽  
G. S. Martínez
Keyword(s):  
Gas Turbine ◽  
Reverse Osmosis ◽  
Gas Turbines ◽  
Waste Heat ◽  
Distillation Unit ◽  
Design Parameters ◽  
Small Scale ◽  
Micro Gas Turbine ◽  
The Cost ◽  
The Impact

Abstract This paper presents the preliminary design and techno-economic assessment of an innovative solar system for the simultaneous production of water and electricity at small scale, based on the combination of a solar micro gas turbine and a bottoming desalination unit. The proposed layout is such that the former system converts solar energy into electricity and rejects heat that can be used to drive a thermal desalination plant. A design model is developed in order to select the main design parameters for two different desalination technologies, phase change and membrane desalination, in order to better exploit the available electricity and waste heat from the turbine. In addition to the usual design parameters of the mGT, the impact of the size of the collector is also assessed and, for the desalination technologies, a tailored multi-effect distillation unit is analysed through the selection of the corresponding design parameters. A reverse osmosis desalination system is also designed in parallel, based on commercial software currently used by the water industry. The results show that the electricity produced by the solar micro gas turbine can be used to drive a Reverse Osmosis system effectively whereas the exhaust gases could drive a distillation unit. This would decrease the stack temperature of the plant, increasing the overall energy efficiency of the system. Nevertheless, the better thermodynamic performance of this fully integrated system does not translate into a more economical production of water. Indeed, the cost of water turns out lower when coupling the solar microturbine and Reverse Osmosis units only (between 3 and 3.5 €/m3), whilst making further use the available waste heat in a Multi Effect Distillation system rises the cost of water by 15%.

Experimental Characterization of a Micro Gas Turbine Test Rig

2010 ◽  
Author(s):  
Martina Hohloch ◽  
Jan Zanger ◽  
Axel Widenhorn ◽  
Manfred Aigner
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Fluid Dynamic ◽  
Electrical Power ◽  
Test Rig ◽  
Data Set ◽  
Micro Gas Turbine ◽  
Electrical Power Output ◽  
The Impact

For the development of efficient and fuel flexible decentralized power plant concepts a test rig based on the Turbec T100 micro gas turbine is operated at the DLR Institute of Combustion Technology. This paper reports the characterization of the transient operating performance of the micro gas turbine by selected transient maneuvers like start-up, load change and shut-down. The transient maneuvers can be affected by specifying either the electrical power output or the turbine speed. The impact of the two different operation strategies on the behavior of the engine is explained. At selected stationary load points the performance of the gas turbine components is characterized by using the measured thermodynamic and fluid dynamic quantities. In addition the impact of different turbine outlet temperatures on the performance of the gas turbine is worked out. The resulting data set can be used for validation of numerical simulation and as a base for further investigations on micro gas turbines.

Limiting the Maintenance Impact of Frequency Regulation Duty on Simple and Combined Cycle Gas Turbine Power Plants

1997 ◽  
Author(s):  
William I. Rowen
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Low Cycle Fatigue ◽  
Combined Cycle ◽  
Frequency Regulation ◽  
Cycle Fatigue ◽  
Thermally Induced ◽  
System Frequency ◽  
The Impact

As more new power plants based on gas turbines enter service, the need for these plants to participate in grid frequency regulation, as opposed to providing blocks of base load power on a dispatchable basis, increases dramatically, exposing this equipment to the potential for accelerated thermal fatigue duty. This paper proposes a methodology for quantifying and limiting the maintenance impact of rapid load changes imposed on gas turbines when required to provide frequency regulation service to the connected utility. The paper includes a discussion of the need for prime movers to participate in system frequency regulation and the impact of this type of service on gas turbine operation. The physics of thermally induced low cycle fatigue is then discussed, and the relationships are quantified using a multiple time constant approach that provides guidance for estimating the transient thermal characteristics of the turbine airfoils that are susceptible to thermally induced low cycle fatigue. This is used to develop the thermo-mechanical relationships that are pertinent to gas turbines in generator drive service. Finally, this material is related back to operational considerations in utilizing gas turbines for system frequency regulation duty.

Addressing the Energy Trilemma With LPG-Fuelled, Water-Free Combined Cycle Power Plants

2020 ◽  
Author(s):  
Michael Welch
Keyword(s):  
Environmental Impact ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
High Efficiency ◽  
Gas Production ◽  
Combined Cycle ◽  
Liquefied Petroleum Gas ◽  
Distributed Power ◽  
The Impact

Abstract Many parts of the world are facing the triple challenge of providing secure energy to fuel economic growth at an affordable cost while minimizing the impact of energy production on the environment. Island nations especially struggle to address this trilemma, as renewable resources are usually limited and fossil fuels imported. Traditionally such distributed power plants have relied on liquid fuels and multiple open cycle reciprocating engines to provide both redundancy and the ability to load follow across a broad load range to maximize efficiency. This approach has created high electricity prices and significant negative environmental impact, especially that attributed to CO2, NOx, and SOx. With increasing natural gas production, the availability of Liquefied Petroleum Gas (LPG) has grown, and costs have fallen, allowing the potential to switch from fuel oils to LPG to reduce environmental impacts. Energy costs and environmental impact can be further reduced by using high efficiency Gas Turbine Combined Cycle plants with dry low emissions combustion technology. However, a further hurdle facing many locations is lack of the fresh water required for combined cycle operations. LPG-fuelled Gas Turbine Combined Cycle using Organic Rankine Cycle (ORC) technology can address all aspects of this energy trilemma. This paper reviews the conceptual design of a proposed 100MW distributed power plant for an island location, based on multiple LPG-fuelled gas turbines to follow load demand, with an ORC bottoming cycle to maximize efficiency.

scholarly journals Thermodynamic Analysis and Process System Comparison of the Exhaust Gas Recirculated, Steam Injected and Humidified Micro Gas Turbine

2015 ◽  
Author(s):  
Usman Ali ◽  
Carolina Font Palma ◽  
Kevin J. Hughes ◽  
Derek B. Ingham ◽  
Lin Ma ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Co2 Enrichment ◽  
Hot Water ◽  
Exhaust Gas ◽  
Electrical Efficiency ◽  
Micro Gas Turbine ◽  
Carbon Dioxide Co2 ◽  
Reduction Of Co2 ◽  
The Impact

Stringent environmental emission regulations and continuing efforts to reduce carbon dioxide (CO2) from the energy sector, in the context of global warming, have promoted interest to improve the efficiency of power generation systems whilst reducing emissions. Further, this has led to the development of innovative gas turbine systems which either result in higher electrical efficiency or the reduction of CO2 emissions. Micro gas turbines are one of the secure, economical and environmentally viable options for power and heat generation. Here, a Turbec T100 micro gas turbine (MGT) is simulated using Aspen HYSYS® V8.4 and validated through experimental data. Due to the consistency and robustness of the steady state model developed, it is further extended to three different innovative cycles: (i) an exhaust gas recirculated (EGR) cycle, in which part of the exhaust gas is dried and re-circulated to the MGT inlet; (ii) a steam injected (STIG) cycle, and (iii) a humid air turbine (HAT) cycle. The steam and hot water are generated through the exhaust of the recuperator for the STIG and HAT cycle, respectively. Further, the steam is directly injected into the recuperator for power augmentation, while for the HAT cycle; the compressed air is saturated with water in the humid tower before entering the recuperator. This study evaluates the impact of the EGR ratio, steam to air ratio, and water to air ratio on the performance and efficiency of the system. The comparative potential for each innovative cycle is assessed by thermodynamic properties estimation of process parameters through the models developed to better understand the behavior of each cycle. The thermodynamic assessment indicates that CO2 enrichment occurs for the three innovative cycles. Further, the results indicate that the electrical efficiency increases for the STIG and HAT cycle while it decreases for the EGR cycle. In conclusion, the innovative cycles indicates the possibilities to improve the system performance and efficiency.

scholarly journals Comprehensive Thermodynamic Analysis of the Humphrey Cycle for Gas Turbines with Pressure Gain Combustion

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3521 ◽  
Author(s):  
Panagiotis Stathopoulos
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Combustion Process ◽  
Ideal Gas ◽  
Point Of View ◽  
Pressure Gain Combustion ◽  
Combustion Technology ◽  
Secondary Air ◽  
And Performance ◽  
The Impact

Conventional gas turbines are approaching their efficiency limits and performance gains are becoming increasingly difficult to achieve. Pressure Gain Combustion (PGC) has emerged as a very promising technology in this respect, due to the higher thermal efficiency of the respective ideal gas turbine thermodynamic cycles. Up to date, only very simplified models of open cycle gas turbines with pressure gain combustion have been considered. However, the integration of a fundamentally different combustion technology will be inherently connected with additional losses. Entropy generation in the combustion process, combustor inlet pressure loss (a central issue for pressure gain combustors), and the impact of PGC on the secondary air system (especially blade cooling) are all very important parameters that have been neglected. The current work uses the Humphrey cycle in an attempt to address all these issues in order to provide gas turbine component designers with benchmark efficiency values for individual components of gas turbines with PGC. The analysis concludes with some recommendations for the best strategy to integrate turbine expanders with PGC combustors. This is done from a purely thermodynamic point of view, again with the goal to deliver design benchmark values for a more realistic interpretation of the cycle.

Sign in / Sign up

Export Citation Format

Share Document