Gas Turbine Part Load Exhaust Gas Emissions Turndown Envelope Testing Methodology

2009 ◽  
Author(s):  
Kristen LeClair ◽  
Thomas Schmitt ◽  
Garth Frederick
Keyword(s):  
Control System ◽  
Gas Turbine ◽  
Fuel Consumption ◽  
Gas Turbines ◽  
Thermodynamic Simulation ◽  
Combined Cycle ◽  
Exhaust Gas ◽  
Ambient Conditions ◽  
Gas Emissions ◽  
Exhaust Gas Emissions

Economic and regulatory requirements have transformed today’s power plant operations. High reserve margins and increased fuel costs have driven combined cycle plants that were once dispatched primarily at base-load to be cycled off during off-peak hours. For many plants, the increased cycling has contributed to shorter maintenance intervals and higher overall operating costs. Technology advancements in combustion system design and in gas turbine control systems has led to extensions in the emissions-compliant operating window of gas turbines, also known as turndown. With extended turndown capability, customers are now able to significantly reduce fuel consumption during minimum load operation at off-peak hours, while simultaneously minimizing the number of shutdowns. Extended turndown reduces operational costs by offsetting the fuel consumption costs against the costs associated with starting up and the maintenance costs associated with such starts. Along with the increased emphasis on turndown capability, there has been a rising need to develop and standardize methods by which turndown capability can be accurately measured and reported. By definition, the limiting factor for turndown is the exhaust gas emissions, primarily CO and NOx. A concurrent and accurate measurement of performance and emissions is an essential ingredient to the determination of turndown capability. Of particular challenge is the method by which turndown results that were measured at one set of ambient conditions can be accurately projected to a specific guarantee condition, or to a range of ambient conditions, for which turndown capabilities have been guaranteed. The turndown projection methodology needs to consider combustion physics, control system algorithms, and basic cycle thermodynamics. Recent advances in the integration of empirically tuned physics-based combustion models with control system models and the gas turbine thermodynamic simulation, has resulted in test procedures for use in the contractual demonstration of turndown capability. A discussion of these methods is presented, along with data showing the extent to which the methods have provided accurate and repeatable test results.

Incremental Fuel Cost Prediction for a Gas Turbine Combined Cycle Utility

1989 ◽  
Author(s):  
D. Little ◽  
H. Nikkels ◽  
P. Smithson
Keyword(s):  
Gas Turbine ◽  
Fuel Consumption ◽  
Gas Turbines ◽  
Operating Experience ◽  
Load Level ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Fuel Cost ◽  
Ambient Conditions ◽  
Cost Prediction

For a medium sized (300 MW) utility producing electricity from a 130 MW combined cycle, and supplemental 15 MW to 77 MW capacity simple cycle gas turbines, the incremental fuel costs accompanying changes in generating capacity vary considerably with unit, health, load level, and ambient. To enable incremental power to be sold to neighbouring utilities on an incremental fuel cost basis, accurate models of all gas turbines and the combined cycle were developed which would allow a realistic calculation of fuel consumption under all operating conditions. The fuel cost prediction program is in two parts; in the first part, gas turbine health is diagnosed from measured parameters; in the second part, fuel consumption is calculated from compressor and turbine health, ambient conditions and power levels. The paper describes the program philosophy, development, and initial operating experience.

Numerical Assessment of SCAP: A Passive System for Preventing Thermoacoustic Oscillations in Gas Turbine Annular Combustors

2007 ◽  
Author(s):  
Stefano Tiribuzi
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Research Unit ◽  
Combined Cycle ◽  
Computational Time ◽  
Computational Domain ◽  
Ambient Conditions ◽  
Pressure Oscillations ◽  
Operation Conditions ◽  
Thermoacoustic Oscillations

ENEL operates a dozen combined cycle units whose V94.3A gas turbines are equipped with annular combustors. In such lean premixed gas turbines, particular operation conditions could trigger large pressure oscillations due to thermoacoustic instabilities. The ENEL Research unit is studying this phenomenon in order to find out methods which could avoid or mitigate such events. The use of effective numerical analysis techniques allowed us to investigate the realistic time evolution and behaviour of the acoustic fields associated with this phenomenon. KIEN, an in-house low diffusive URANS code capable of simulating 3D reactive flows, has been used in the Very Rough Grid approach. This approach permits the simulation, with a reasonable computational time, of quite long real transients with a computational domain extended over all the resonant volumes involved in the acoustic phenomenon. The V94.3A gas turbine model was set up with a full combustor 3D grid, going from the compressor outlet up to the turbine inlet, including both the annular plenum and the annular combustion chamber. The grid extends over the entire circular angle, including all the 24 premixed burners. Numerical runs were performed with the normal V94.3A combustor configuration, with input parameters set so as no oscillations develop in the standard ambient conditions. Wide pressure oscillations on the contrary are associated with the circumferential acoustic modes of the combustor, which have their onset and grow when winter ambient conditions are assumed. These results also confirmed that the sustaining mechanism is based on the equivalence ratio fluctuation of premix mixture and that plenum plays an important role in such mechanism. Based on these findings, a system for controlling the thermoacoustic oscillation has been conceived (Patent Pending), which acts on the plenum side of the combustor. This system, called SCAP (Segmentation of Combustor Annular Plenum), is based on the subdivision of the plenum annular volume by means of a few meridionally oriented walls. Repetition of KIEN runs with a SCAP configuration, in which a suitable number of segmentation walls were properly arranged in the annular plenum, demonstrated the effectiveness of this solution in preventing the development of wide thermoacoustic oscillations in the combustor.

Development of an Interactive Code for Design and Off-Design Performance Evaluation of Gas Turbines

2009 ◽  
Author(s):  
Behnam Rezaei Zangmolk ◽  
Hiwa Khaledi
Keyword(s):  
Control System ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Combined Cycle ◽  
Design Performance ◽  
Blade Cooling ◽  
Constant Control ◽  
Model Component ◽  
Surge Line ◽  
Cooling Model

In this paper, development of a modular code for simulation of design and off-design performance of different gas turbines (with different shafts and technology) has been described. This interactive code will be used for different purposes in MPG Company. This turbomachinery and thermodynamic model is based on compressor and turbine maps and blade cooling has been considered with a cooling model. Component maps and effect of IGV have been developed from one of 1D, 2D or Q3d in-house codes. It is demonstrated that this model is accurate for prediction of gas turbine behavior at both design and off-design conditions. Effect of various control system — IGV constant, TIT constant and TET constant — is evaluated. These results show that IGV constant control system has the highest and TIT constant have the lowest efficiency for a simple cycle gas turbine. In contrast, the reverse is true in a combined cycle. Also the results show that the compressor is the most stable and away enough from surge line with IGV constant control system and has the highest efficiency.

Influence of TiO2 and Bio-Solution Based Additives on Exhaust Emissions of a DI Diesel Engine

2012 ◽  
Vol 602-604 ◽  
pp. 1054-1058
Author(s):  
Karoon Fangsuwannarak ◽  
Kittichai Triratanasirichai
Keyword(s):  
Fuel Consumption ◽  
Direct Injection ◽  
Exhaust Emissions ◽  
Specific Fuel Consumption ◽  
Exhaust Gas ◽  
Gas Emissions ◽  
Fire Point ◽  
Di Diesel Engine ◽  
Nano Titanium Dioxide ◽  
Exhaust Gas Emissions

This study presents the use of bio-solution and nano-Titanium dioxide (TiO2) based additives for dosing in diesel and palm biodiesel (B5). The aim of this work is to enhance the performance of a direct injection (DI) engine and to simultaneously reduce the exhaust gas emissions. The basic properties such as kinematic viscosity, specific gravity, flash point, fire point, and carbon residue of the test fuels were measured and accepted in ASTM standards. Overall, diesel-bio-solution and diesel-TiO2 blends show the lower break specific fuel consumption by 13% and 10%, respectively and the lower exhaust gas emissions, as compared with diesel. B5-bio-solution blend provides the break specific fuel consumption decreased by 1.68%, while exhaust emissions were effectively increased in comparison with B5 fuel.

Control Optimization for Multiple Gas Turbine Driven Compressors

2018 ◽  
Author(s):  
Roman Zamotorin ◽  
Rainer Kurz ◽  
Donghui Zhang ◽  
Matt Lubomirsky ◽  
Klaus Brun
Keyword(s):  
Control System ◽  
Gas Turbine ◽  
Fuel Consumption ◽  
Gas Turbines ◽  
Simple Algorithm ◽  
Optimization Methods ◽  
Operational Parameters ◽  
Control Optimization ◽  
Identical Machines ◽  
Measured Change

Many gas compressor stations use multiple gas turbine driven centrifugal compressors. In many instances, the units are not identical. The challenge is to control the units such, that certain operational parameters, for example fuel consumption, are optimized. The control system has to rely on measurable parameters. The system has to be reliable even if parameters that are not directly measured change during operation. For practical use, the two methods available are to control all compressors for the same turndown, or to control all gas turbines for the same load. This methodology can be derived and discussed for the case of identical machines, and will be expanded for the case where the compressors and their drivers are not identical. The paper describes a variety of optimization methods, starting with a simple algorithm, then comparing equalization methods, and finally illustration the capability of methods that combine turbomachinery optimization and the optimization of pipeline hydraulics.

Influence of Advancements in Gas Turbine Control Systems on Gas Turbine and Combined-Cycle Performance Test Correction Curves

2011 ◽  
Author(s):  
Thomas P. Schmitt ◽  
Christopher R. Banares ◽  
Benjamin D. Morlang ◽  
Matthew C. Michael
Keyword(s):  
Control System ◽  
Boundary Conditions ◽  
Control Systems ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Performance Test ◽  
Combined Cycle ◽  
Plant Performance ◽  
Control Algorithms ◽  
Technical Accuracy

Many modern power plants feature gas turbines with advanced control systems that allow a greater level of performance enhancements, over a broader range of the combined-cycle plant’s operating environment, compared to conventional systems. Control system advancements tend to outpace a plant’s construction and commissioning timescale. Often, the control algorithms and settings in place at the final guarantee performance test will differ significantly from those envisioned during the contract agreement phase. As such, the gas turbine’s actual performance response to changes in boundary conditions, such as air temperature and air humidity, will be considerably different than the response illustrated on the initial correction curves. For the sake of technical accuracy, the performance correction curves should be updated to reflect the as-built, as-left behavior of the plant. By providing the most technically accurate curves, the needs of the new plant performance test are satisfied. Also, plant operators receive an accurate means to trend performance over time. The performance correction curves are intended to provide the most technically accurate assurance that the corrected test results are independent of boundary conditions that persist during the performance test. Therefore, after the gas turbine control algorithms and/or settings have been adjusted, the performance correction curves — whether specific to gas turbines or overall combined-cycle plants — should be updated to reflect any change in turbine response. This best practice maintains the highest level of technical accuracy. Failure to employ the available advanced gas turbine control system upgrades can limit the plant performance over the ambient operating regime. Failure to make a corresponding update to the correction curves can cause additional inaccuracy in the performance test’s corrected results. This paper presents a high-level discussion of GE’s recent gas turbine control system advancements, and emphasizes the need to update performance correction curves based on their impact.

Flexible Combined Cycle Gas Turbine Power Plant Utilising Organic Rankine Cycle Technology

2016 ◽  
Author(s):  
Michael Welch ◽  
Nicola Rossetti
Keyword(s):  
Power Generation ◽  
Power Plant ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Exhaust Gas ◽  
Operational Flexibility

Historically gas turbine power plants have become more efficient and reduced the installed cost/MW by developing larger gas turbines and installing them in combined cycle configuration with a steam turbine. These large gas turbines have been designed to maintain high exhaust gas temperatures to maximise the power generation from the steam turbine and achieve the highest overall electrical efficiencies possible. However, in today’s electricity market, with more emphasis on decentralised power generation, especially in emerging nations, and increasing penetration of intermittent renewable power generation, this solution may not be flexible enough to meet operator demands. An alternative solution to using one or two large gas turbines in a large central combined cycle power plant is to design and install multiple smaller decentralised power plant, based on multiple gas turbines with individual outputs below 100MW, to provide the operational flexibility required and enable this smaller power plant to maintain a high efficiency and low emissions profile over a wide load range. This option helps maintain security of power supplies, as well as providing enhanced operational flexibility through the ability to turn turbines on and off as necessary to match the load demand. The smaller gas turbines though tend not to have been optimised for combined cycle operation, and their exhaust gas temperatures may not be sufficiently high, especially under part load conditions, to generate steam at the conditions needed to achieve a high overall electrical efficiency. ORC technology, thanks to the use of specific organic working fluids, permits efficient exploitation of low temperatures exhaust gas streams, as could be the case for smaller gas turbines, especially when working on poor quality fuels. This paper looks at how a decentralised power plant could be designed using Organic Rankine Cycle (ORC) in place of the conventional steam Rankine Cycle to maximise power generation efficiency and flexibility, while still offering a highly competitive installed cost. Combined cycle power generation utilising ORC technology offers a solution that also has environmental benefits in a water-constrained World. The paper also investigates the differences in plant performance for ORC designs utilising direct heating of the ORC working fluid compared to those using an intermediate thermal oil heating loop, and looks at the challenges involved in connecting multiple gas turbines to a single ORC turbo-generator to keep installed costs to a minimum.

Experimental Investigation of a FLOX®-Based Combustor for a Small-Scale Gas Turbine Based CHP System Under Atmospheric Conditions

2015 ◽  
Author(s):  
Hannah Seliger ◽  
Andreas Huber ◽  
Manfred Aigner
Keyword(s):  
Experimental Investigation ◽  
Gas Turbine ◽  
Electrical Power ◽  
Small Scale ◽  
Exhaust Gas ◽  
Atmospheric Conditions ◽  
Gas Emissions ◽  
Micro Gas Turbine ◽  
Electrical Power Output ◽  
Exhaust Gas Emissions

This paper presents a comprehensive experimental investigation of a newly designed single-stage combustion system based on the flameless oxidation (FLOX®) technology for a small scale micro gas turbine (MGT). It is used for a combined heat and power plant (CHP) with an electrical power output of 3 kW, using natural gas as fuel. Flameless oxidation is characterized by a flame distributed over a large volume and a high internal recirculation of flue gas. Considering the high combustor inlet temperatures up to 1000 K as required for this application, the FLOX®-combustion concept offers various advantages compared to swirl-stabilized combustion systems in terms of flashback risk and exhaust gas emissions. This paper describes the detailed characterization of the jet-stabilized combustor. Two versions of the combustor were tested, one generic and one modified version suitable for the integration into the micro gas turbine at an atmospheric test rig with optical access. The stable operating range, including lean blow out (LBO) limits, was determined for varying equivalence ratios, thermal powers and preheat temperatures. The influence of these parameters on the combustion characteristics is discussed. Furthermore, the shape and location of the heat release zone is investigated with OH*-chemiluminescence (OH* CL). The exhaust gas emissions NOx, CO and unburned hydrocarbon (UHC) were also measured. The results demonstrate that the developed combustor design ensures stable and reliable performance. It also offers a high operational flexibility and low pressure loss with NOx, CO and UHC emissions far below regulation limits for all relevant engine conditions.

Modified Rankine HRSG Beats Triple-Pressure System

1996 ◽  
Author(s):  
Peter Eisenkolb ◽  
Martin Pogoreutz ◽  
Hermann Halozan
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Heat Recovery ◽  
Power Plants ◽  
Fossil Fuels ◽  
Combined Cycle ◽  
Exhaust Gas ◽  
Pressure System ◽  
Exergy Losses

Gas-fired combined cycle power plants (CCP) are presently the most efficient systems for producing electricity with fossil fuels. Gas turbines have been and are being improved remarkably during the last years; presently they achieve efficiencies of more than 38% and gas turbine outlet temperatures of up to 610°C. These high outlet temperatures require modifications and improvements of heat recovery steam generators (HRSG). Presently dual pressure HRSGs are most commonly used in combined cycle power stations. The next step seems to be the triple-pressure HRSG to be able to utilise the high gas turbine outlet temperatures efficiently and to reduce exergy losses caused by the heat transfer between exhaust gas and the steam cycle. However, such triple-pressure systems are complicated considering parallel tube bundles as well as start up operation and load changes. For that reason an attempt has been made to replace such multiple pressure systems by a modified Rankine cycle with only a single-pressure level. In the case of the same total heat transfer surfaces this innovative single-pressure system achieves approximately the same efficiency as the triple-pressure system. By optimising the heat recovery from the exhaust gas to the steam/water cycle, i.e. minimising exergy losses, the stack temperature is much higher. Increasing the heat transfer surfaces means a decrease of the stack temperature and a further improvement of the overall CCP-efficiency. Therefore one has to be aware that the proposed system offers advantages not only in the case of a foreseeable increase of gas turbine outlet temperatures but also for presently available gas turbines. Using existing highly efficient gas turbines and subcritical steam conditions, power plants with this proposed Eisenkolb Single Pressure (ESP_CCP) heat recovery steam generator achieve thermal efficiencies of about 58.7% (LHV).

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