scholarly journals Results of the GT Prime Program Improvements to General Electric MS7001B Gas Turbines at the Houston Light and Power T.H. Wharton Site

Author(s):  
Jerome Svatek ◽  
Michael Elliott ◽  
Paul Crabtree ◽  
Gerald E. Jurczynski ◽  
John R. (Bob) Johnston

At the time of the start of the GT PRIME upgrade project, the eight General Electric MS7001 gas turbines in combined cycle service at the Wharton Station of Houston lighting and Power each had 85,000 hours of operation with 2000 starts. The units were ready for their second major overhaul. A number of hot gas path components required replacement at that time. Rather than replacing components one by one, the user devised a Program for Reliability, Improved Maintenance, and Efficiency (GT PRIME). We will discuss turbine condition, design changes, reduced emissions, and increased output in the paper. Actual user experience on maintenance and operating costs resulted in some special requirements to be satisfied in addition to the expected parts replacement. General Electric had developed many improved parts for newer units, all of which could be easily applied to older machines. The use of these newer production MS7001EA parts increase component life, parts availability, inspection intervals, system reliability and performance. These will be described in the paper. These 1972 vintage turbines achieved a 50PPM NOx level by injecting water at a high rate of flow which resulted in the need for more frequent combustion inspection intervals. The development of a dry low NOx system for the unit allowed the combustion inspection interval to double while reducing NOx to 25PPM. The improvement in component efficiencies in the gas path resulted in increased output and improved the heat rate. These changes had a significant impact on customer operating costs which resulted in a very attractive payback period. We will discuss expected versus actual output, heat rate and emissions results for all eight units. The upgrade of the first unit started in 1992 and the last unit was completed in 1996. A detailed listing of uprate program schedule by unit is listed in Figure #1.

Author(s):  
Edward M. Fuselier ◽  
David K. Prugger

The eight General Electric MS7001B gas turbines in combined cycle service at the T.H. Wharton Station of Houston Lighting and Power currently have 85000 hours of operation with 2000 starts. The units are ready for their second major overhaul. A number of hot gas path components will require replacement at that time. Rather than replacing components one by one the user devised a Program for Reliability, Improved Maintenance and Efficiency (GT Prime) with an objective of achieving twenty additional years of trouble free service. Fortunately, the supplier had developed many improved parts for his newer units which could be applied to older machines with an attendant increase in component life, inspection intervals, system reliability, availability and performance. The significant impact on customer operating costs resulted in a very attractive payback period. A contract for modification of all eight units was signed in December, 1991. Teardown of the first unit for modification started in November, 1992 with the rebuild and test completed in July, 1993. This paper will discuss turbine condition, differences between the old and new parts, improved performance and reduced emissions attained as a result of implementing the program.


Author(s):  
Michel Arnal

This paper reviews specific methods used by Wood Group Gas Turbine Services for boosting power output and improving heat rate for existing industrial gas turbines. The methods employed allow operators to make the most of existing equipment as a cost-effective alternative to the replacement of a complete engine. The article summarizes experience with the service and uprate of General Electric Frame 6B gas turbines using the company’s Advanced Parts Manufacture (APM™) turbine parts. A comparison of output and heat rate before and after service allows estimates of the performance improvement for individual components and combinations of hot gas path parts. Such comprehensive upgrades can be implemented only in older generation gas turbines that are part of a model line which the original equipment manufacturer (OEM) has redesigned. An ideal example of such a gas turbine model is the General Electric Frame 6B series. Wood Group Gas Turbine Services has extensive experience in overhauling and uprating the complete range of Frame 6B gas turbines. The company’s replacement parts have been installed in all stages of the hot gas path both as complete sets and in stages in combination with OEM parts in neighboring stages. Examples of components which can be upgraded include: • Turbine vanes and blades; • Combustion Lines and transition pieces; • Heat shields / shroud blocks; • Seals and clearances. All of these can be installed to increase the engine firing temperature and improve performance. The performance data is corrected to ISO conditions to enable a fair and meaningful comparison. The different configurations employed for the overhauls also permit estimates of the contribution of the replacement parts to the overall improvement in performance. Design details of the advanced technology parts are described as needed to provide understanding for the improvements in engine efficiency.


Author(s):  
Xiaomo Jiang ◽  
Craig Foster

Gas turbine simple or combined cycle plants are built and operated with higher availability, reliability, and performance in order to provide the customer with sufficient operating revenues and reduced fuel costs meanwhile enhancing customer dispatch competitiveness. A tremendous amount of operational data is usually collected from the everyday operation of a power plant. It has become an increasingly important but challenging issue about how to turn this data into knowledge and further solutions via developing advanced state-of-the-art analytics. This paper presents an integrated system and methodology to pursue this purpose by automating multi-level, multi-paradigm, multi-facet performance monitoring and anomaly detection for heavy duty gas turbines. The system provides an intelligent platform to drive site-specific performance improvements, mitigate outage risk, rationalize operational pattern, and enhance maintenance schedule and service offerings via taking appropriate proactive actions. In addition, the paper also presents the components in the system, including data sensing, hardware, and operational anomaly detection, expertise proactive act of company, site specific degradation assessment, and water wash effectiveness monitoring and analytics. As demonstrated in two examples, this remote performance monitoring aims to improve equipment efficiency by converting data into knowledge and solutions in order to drive value for customers including lowering operating fuel cost and increasing customer power sales and life cycle value.


Author(s):  
Arthur Cohn ◽  
Mark Waters

It is important that the requirements and cycle penalties related to the cooling of high temperature turbines be thoroughly understood and accurately factored into cycle analyses and power plant systems studies. Various methods used for the cooling of high temperature gas turbines are considered and cooling effectiveness curves established for each. These methods include convection, film and transpiration cooling using compressor bleed and/or discharge air. In addition, the effects of chilling the compressor discharge cooling gas are considered. Performance is developed to demonstrate the impact of the turbine cooling schemes on the heat rate and specific power of Combined–Cycle power plants.


Author(s):  
S. Can Gülen

Duct firing in the heat recovery steam generator (HRSG) of a gas turbine combined cycle power plant is a commonly used method to increase output on hot summer days when gas turbine airflow and power output lapse significantly. The aim is to generate maximum possible power output when it is most needed (and, thus, more profitable) at the expense of power plant heat rate. In this paper, using fundamental thermodynamic arguments and detailed heat and mass balance simulations, it will be shown that, under certain boundary conditions, duct firing in the HRSG can be a facilitator of efficiency improvement as well. When combined with highly-efficient aeroderivative gas turbines with high cycle pressure ratios and concomitantly low exhaust temperatures, duct firing can be utilized for small but efficient combined cycle power plant designs as well as more efficient hot-day power augmentation. This opens the door to efficient and agile fossil fuel-fired power generation opportunities to support variable renewable generation.


Author(s):  
Walter I. Serbetci

As the second study in a sequence of studies conducted on the optimization of combined cycle plants [Ref. 1], this paper presents the effects of fuel gas heating on plant performance and plant economics for various 1×1×1 configurations. First, the theoretical background is presented to explain the effects of fuel gas heating on combustion turbine efficiency and on the overall efficiency of the combined cycle plant. Then, *CycleDeck-Performance Estimator™ and *GateCycle™ computer codes were used to investigate the impact of fuel gas heating on various 1×1×1 configurations. The configurations studied here are: 1) GE CC107FA with three pressure/reheat HRSG and General Electric PG7241(FA) gas turbine (Fig. 1), 2) GE CC106FA with three pressure/reheat HRSG and General Electric PG6101(FA) gas turbine and, 3) GE CC 107EA with three pressure/non-reheat HRSG with General Electric PG7121(EA) gas turbine. In all calculations, natural gas with high methane percentage is used as a typical fuel gas. Hot water from the outlet of IP economizer is used to heat the fuel gas from its supply temperature of 80 °F (27 °C). Heating the fuel gas to target temperatures of 150 °F, 200 °F, 250° F, 300 °F, 350 °F, 375 °F, 400 °F and 425 °F ( 66, 93, 121, 149, 177, 191, 204 and 218 °C), the combustion turbine power output, the combustion turbine heat rate and the plant power output and the corresponding heat rate are determined for each target fuel temperature. For each configuration, the heat transfer surface required to heat the fuel gas to the given target temperatures are also determined and budgetary price quotes are obtained for the fuel gas heaters. As expected, as the fuel temperature is increased, the overall efficiency (therefore the heat rate) improved, however at the expense of some small power output loss. Factoring in the fuel cost savings, the opportunity cost of the power lost, the cost of the various size performance heaters and the incremental auxiliary power consumption (if any), a cost-benefit analysis is carried out and the economically optimum fuel temperature and the corresponding performance heater size are determined for each 1×1×1 configuration.


Author(s):  
Iacopo Giovannetti ◽  
Manuele Bigi ◽  
Massimo Giannozzi ◽  
Dieter R. Sporer ◽  
Filippo Cappuccini ◽  
...  

An improvement in the energy efficiency of industrial gas turbines can be accomplished by developing abradable seals to reduce the stator/rotor gap to decrease the tip leakage flow of gases in the hot gas components of the turbine. “ABRANEW” is a project funded by the European Commission aimed at developing a high temperature abradable material capable of controlled abrasion and resistant to erosion and oxidation. In order to define the basic parameters such as the component shape, the existing gap, the expected gap reduction, the seal thickness and other geometric parameters, a comprehensive review of the design of the blade/shroud/casing system was performed.


Author(s):  
Dieter Bohn ◽  
Robert Krewinkel

Within Collaborative Research Center 561 “Thermally Highly Loaded, Porous and Cooled Multi-Layer Systems for Combined Cycle Power Plants” at RWTH Aachen University an effusion-cooled multi-layer plate configuration with seven staggered effusion cooling holes is investigated numerically by application of a 3-D in-house fluid flow and heat transfer solver, CHTflow. The effusion-cooling is realized by finest drilled holes with a diameter of 0.2 mm that are shaped in the region of the thermal barrier coating. Oxidation studies within SFB 561 have shown that a corrosion layer of several oxides with a thickness of appoximately 20μm grows from the CMSX-4 substrate into the cooling hole. The goal of this work is to investigate the effect this has on the cooling effectiveness, which has to be quantified prior to application of this novel cooling technology in real gas turbines. In order to do this, the influence on the aerodynamics of the flow in the hole, on the hot gas flow and the cooling effectiveness on the surface and in the substrate layer are discussed. The adverse effects of corrosion on the mechanical strength are not a part of this study. A hot gas Mach-number of 0.25 and blowing ratios of approximately 0.28 and 0.48 are considered. The numerical grid contains the coolant supply (plenum), the solid body for the conjugate calculations and the main flow area on the plate. It is shown that the oxidation layer does significantly affect the flow field in the cooling holes and on the plate, but the cooling effectiveness differs only slightly from the reference case. This seems to justify modelling the holes without taking account of the oxidation.


Author(s):  
Erwin Zauner ◽  
Yau-Pin Chyou ◽  
Frederic Walraven ◽  
Rolf Althaus

Power generation in gas turbines is facing three main challenges today: • Low pollution prescribed by legal requirements. • High efficiency to obtain low operating cost and low CO2 emissions. • High specific power output to obtain low product and installation cost. Unfortunately, some of these requirements are contradictory: high efficiency and specific power force the development towards higher temperatures and pressures which increase NOx emissions and intensify the cooling and material strength problems. A breakthrough can be achieved by applying an energy exchanger as a topping stage. Inherent advantages are the self-cooled cell-rotor which can be exposed to much higher gas temperature than a steady-flow turbine and a very short residence time at peak temperature which keeps NOx emissions under control. The basic idea has been proposed long time ago. Fundamental research has now led to a new energy exchanger concept. Key issues include symmetric pressure-wave processes, partial suppression of flow separation and fluid mixing, as well as quick afterburning in premixed mode. The concept has been proven in a laboratory-scale engine with very promising results. The application of an energy exchanger as a topping stage onto existing gas turbines would increase the efficiency by 17% (relative) and the power by 25%. Since the temperature level in the turbine remains unchanged, the performance improvement can also be fully utilized in combined cycle applications. This process indicates great potentials for developing advanced gas turbine systems as well as for retrofitting existing ones.


1979 ◽  
Author(s):  
R. J. Rossbach

The General Electric Company is carrying out a design study and evaluation of bottoming cycles for gas pipeline compressor prime movers. Three sites were chosen for the study of demonstration organic bottoming cycles of about 5000 hp applied to three aircraft derivative gas turbines of approximately the same size. The purpose of the study is to design and evaluate all important aspects of installing organic bottoming cycle systems on a selected group of gas turbine prime movers driving gas compressors. As a result of the study, it was found that pipeline bottoming cycles applied to gas turbine prime movers could reduce the heat rate 35 percent more than the Department of Energy target value of 20 percent. Installation designs for three sites are described.


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