Heavy Duty Industrial Gas Turbine Research Articles

Performance and Techno-Economic Analysis of Inlet Fogging System Implementation in Heavy Duty Industrial Gas Turbines

This study investigates the performance and economic benefits of applying inlet fogging in a heavy duty industrial gas turbine. To achieve the aim of the study, a heavy duty industrial gas turbine engine was modelled using a gas turbine performance software, GasTurb. The modelled engine was derived from the Frame 9E class of gas turbines. Consequent upon completing the engine modelling, ambient temperature profile data obtained from a location in Niger Delta region of Nigeria were used as input into the engine model to simulate its effect on the engine performance. Inlet fogging was simulated on the industrial gas turbine by inputting a water-to-air ratio of 0.4%, to cool and reduce the air inlet temperature by 10 degree Celsius. The simulation plots show that the gas turbine performance which dropped as a result of increased ambient temperature was enhanced by the application of inlet fogging. Economic analysis shows that approximately $2.4 million profit was recorded in one year when inlet fogging system was employed.

Metallurgical Failure Analysis of Cracked First Stage Vane of Heavy-Duty Industrial Gas Turbine Engine for Power Generation

Abstract A first stage turbine vane of a heavy-duty gas turbine engine, exhibiting an outward bulge of approximately 0.6 mm and a visible crack in the top coating, was delivered by the client for a detailed destructive failure investigation. The subject component was an experimental part used in a test field engine. The suction side wall of the casting was cut off to reveal a gaping crack on the inside of the aft cavity that was also visible by borescopic inspection. The cooling insert of the aft cavity was clean and did not have any blocked cooling holes. The cooling pattern on the inside wall of the aft cavity was unremarkable. No evidence whatever of impact damage was found on the suction side surface of the subject vane in the cracked region. The hypothesis as to the most probable root cause of the cracking that is still standing is a combination of low wall thickness, non-optimal process parameters for bond coat pre-heat, and potentially high thermal/mechanical loading during engine operation. It appears this is not a wide-spread phenomenon but rather an isolated occurrence.

Pressure gain combustion advantage in land-based electric power generation

AbstractThis article evaluates the improvement in gas turbine combined cycle power plant efficiency and output via pressure gain combustion (PGC). Ideal and real cycle calculations are provided for a rigorous assessment of PGC variants (e.g., detonation and deflagration) in a realistic power plant framework with advanced heavy-duty industrial gas turbines. It is shown that PGC is the single-most potent knob available to the designers for a quantum leap in combined cycle performance.

Prospects of deployment of Jatropha biodiesel-fired plants in Nigeria’s power sector

This paper presents the techno-economic performance analysis of Jatropha biodiesel-fired power plants in comparison with natural gas- and diesel-fired plants. Jatropha biodiesel can be substituted for natural gas in industrial gas turbines at a slight loss in power output of ∼2% and plant efficiency of ∼1%. The exclusive use of the fuel in heavy duty industrial gas turbines is not economically viable at existing electricity generation prices in Nigeria, except fuels are restricted to combined cycle engines and considered as biomass power plants. The Levelized Cost of Electricity (LCOE) of the Jatropha biodiesel-fired plants varied from $0.203–0.252/kWh, values that are below the cost of self-generated electricity (SGE) in Nigeria —$0.45–0.70/kWh. To integrate Jatropha biodiesel into existing power plants, a minimum production-based incentive (PBI) of $0.052–0.082/kWh can be provided for up to nine years or maximum partial fuel substitution (PFS) of 33–40% can be mandated, depending on the mode of operation. A guaranteed fuel price of $0.18–5/gallon can be ensured, depending on electricity contract price. A carbon tax up to $100/tCO2 can also be imposed on natural gas-fired plants, but this does not ensure economic viability. The high cost of SGE in Nigeria uncovers an opportunity for embedded power generation.

Distributed Real Time Compressor Blade Health Monitoring System

Compressor blades of a heavy duty industrial gas turbine need to sustain long period mechanical stress and vibration induced by high speed rotation and high pressure mass flow. High stress coupled with erosion and corrosion damage during operation is the main driver for blade cracking. Material separation of cracked rotating blade is a serious safety and reliability concern, which not only affects compressor health, but may also cause costly secondary damage at downstream. Early detection of blade anomaly and incipient crack is critical to ensure blade and compressor health and minimize service disruption. In this paper we will introduce a blade health monitoring (BHM) system developed by GE Power. BHM adopts distributed system architecture and operates continuously 24x7 to provide real time rotor blade health assessment. BHM sensors and data acquisition (DAQ) system are installed on the gas turbine to capture blade passing signals (BPS) and assess time of arrival (TOA) for each blade. Advanced signal processing algorithms process the signals locally to calculate key features that associated with blade health. Then finally, a central anomaly detection module, which is fully integrated with GE Power monitoring system, is developed to assess blade health condition and generate anomaly alarms to alert diagnostic engineer.

CFD evaluation of pressure drop across a 3-D filter housing for industrial gas turbine plants

This paper investigated the flow distribution and total pressure drop across a designed 3-D filter housing integrated with a 3-stage filtration system using computational fluid dynamics (CFD). The filter housing model was proposed for a heavy-duty industrial gas turbine plant operating at an average ambient temperature of 20°C.The pressure drops across the classes of filters were 652.8 Pa, 2692.2 Pa, 887.8 Pa, 776.2 Pa and 2304.2 Pa for I-GB, GB-GA, GA-FA, FA-HA, and HA-O, respectively. The results obtained indicated an acceptable total pressure drop of 7.2% for the entire filter housing before filter clean-up. Although the CFD simulation result shows that small outlet flow velocity and transonic flows exist at the outlet of the filter housing, the designed filter housing was proved compatible with the studied GT, for inlet flow conditions between 600⩽Wair⩽610 kg/s and 60⩽vair⩽70 m/s for the air flow rate and velocity, respectively. Furthermore, the designed filter housing could be adopted for the studied GT and locations of Usan and Maiduguri in Nigeria, and other locations with similar environmental conditions.

Correlation Analysis of Multiple Sensors for Industrial Gas Turbine Compressor Blade Health Monitoring

This paper summarizes an analysis of data obtained from an instrumented compressor of an operational, heavy duty industrial gas turbine; the goal of the aforementioned analysis is to understand some of the fundamental drivers, which may lead to compressor blade vibration. Methodologies are needed to (1) understand the fundamental drivers of compressor blade vibration, (2) quantify the severity of “events,” which accelerate the likelihood of failure and reduce the remaining life of the blade, and (3) proactively detect when these issues are occurring so that the operator can take corrective action. The motivation for this analysis lies in understanding the correlations between different sensors, which may be used to measure the fundamental drivers and blade vibrations. In this study, a variety of dynamic data was acquired from an operating engine, including acoustic pressure, bearing vibration, tip timing, and traditional gas path measurements. The acoustic pressure sensors were installed on the first four compressor stages, while the tip timing was installed on the first stage only. These data show the presence of rotating stall instabilities in the front stages of the compressor, occurring during every startup and shutdown, and manifesting itself as increased amplitude oscillations in the dynamic pressure measurements, which are manifested in blade and bearing vibrations. The data that lead to these observations were acquired during several startup and shutdown events, and clearly show that the amplitude of these instabilities and the rpm at which they occur can vary substantially.

Intergranular Corrosion in Retaining Rings Made of X39CrMo17-1 and X39Cr13

Abstract A number of retaining rings used in fuel gas piping assemblies of large stationary heavy-duty industrial gas turbines were found broken upon reception at the gas turbine manufacturer's plant. While the pipes were made of AISI 321 austenitic stainless steel, 1.4541, X6CrNiTi18-10, the specified material of the subject locking rings is the martensitic stainless chromium steel X39CrMo17-1, 1.4122. In fact, however, the failed snap rings consisted of the lower-chromium X39Cr13, 1.4031. The fractured retaining rings all originated from a particular North American supply chain. In contrast, the same pipe assemblies delivered by an alterna­tive second-source European supplier did not show these remarkable fractures in their retain­ing rings. Also, they were indeed made of the specified higher-chromium material. It was later discovered that the supplier that shipped the faulty product employed a peculiar wet cleaning process without proper post-cleaning drying. The conclusion of the metallurgical failure analysis was that the subject retaining rings failed by intergranular corrosion due to sensitisation from heat treatment and wet cleaning residues that remained on the product and caused corrosion during shipment. The erroneous material selection, violating the specifica­tion, contributed to the failure.

Transformation of Delta Ferrite Into Sigma Phase in Metastable Austenitic Stainless Steels After Long-Term High-Temperature Service Exposure

Abstract A service temperature increase of turbine exhaust casing liners of heavy-duty industrial gas turbines, driven by the need to raise thermal efficiencies, motivated a number of ageing trials. Casing liners are often made of metastable austenitic stainless steels, suitable for high temperature applications. Alloys such as 321SS and 347SS might contain, in the as-cast condition, rather large amounts of delta ferrite, if not further processed by rolling or forging, easily in excess of 15 %. Even rolled sheet and bar might contain significant volume fractions of that phase if welded, up to 15 % or so in the heat affected zone (HAZ) immediately adjacent to the fusion line, and in the weld metal. It is known from the literature and from field experience that delta ferrite might decompose into sigma phase after long-term service exposure at elevated temperatures. This may embrittle the material and can be detrimental to mechanical properties. It could also deleteriously affect creep strength. The main aim of ageing trials described in this paper was to study the phase stability of delta ferrite under simulated service conditions. The results are correlated to metallographic testing results, obtained from examining actual service components of heavy-duty gas turbine engines in the field.

Reverse engineering of turbine blades based on design intent

The purpose of this paper is to describe a new approach to process the data points measured from turbine blade airfoils in order to make a valid shape via reverse engineering method. Currently, preliminary B-rep models can be created by fitting surfaces to point clouds using a 3D laser scanner. In case of a turbine blade, due to high shape complexity, the resulting model is often unsuitable in practice. A small change in blade geometry can lead to a large change in turbine performance. Therefore, control of the blade shape is critical to the design process. Authors believe that the only way to capture the valid shape of a blade airfoil out of the many manufacturing deviations is to incorporate design key-points during reverse engineering. Implementation of the new method using segmentation and constrained fitting algorithm (SCFA) on a heavy-duty industrial gas turbine blade has been reported and discussed.

Development and Evaluation of a High-Resolution Turbine Pyrometer System

Optical pyrometers provide many advantages over intrusive measuring techniques in determining the spatial and time varying temperature distribution of fast rotating components in gas turbines. This paper describes the development and evaluation of a versatile high-resolution pyrometer system and its application to radial turbine rotor temperature mapping as has been done in a R&D project at the Technical University Berlin under funding from Siemens Power Generation (KWU). The development goal was a pyrometer system with a temporal resolution of 1 μs, a minimum field of view of 1 mm, and a measurement range from 600 to 1500°C. A prototype of the pyrometer system has been built and tested at the small gas turbine test facility of the Technical University Berlin. The system yielded excellent results with respect to measurement uncertainty, resolution, and reliability. Finally, measurement results obtained with the new system on a radial turbine rotor and on a heavy duty industrial gas turbine are compared with measurements conducted with a commercially available turbine pyrometer system.

Compressor Discharge Brush Seal for Gas Turbine Model 7EA

AbstractSingle-shaft, heavy-duty industrial gas turbines are extremely sensitive to compressed air bypassing at compressor discharge plane. This plane represents the highest pressure location in entire gas turbine unit (GTU). Standard method to minimize compressed air leakage is labyrinth seal that is integral part of the cylindrical element here called "inner barrel." The inner barrel is also the part of compressor discharge diffuser. This paper describes the efforts related to conversion of standard labyrinth seal into the hybrid seal that is combination of labyrinth and brush seals.

Development of catalytic combustion technology for single-digit emissions from industrial gas turbines

Catalytic combustion has demonstrated potential for attaining the firing temperatures of current and next generation gas turbines with nitrogen oxides (NO x ) production less than 3 parts-per-million by volume (ppmv), using natural gas fuel. The technology necessary to achieve this extremely low emissions performance with typical heavy-duty industrial and utility gas turbine operating cycle conditions, has been under development as a joint effort by the General Electric Company (GE) and Catalytica Combustion Systems Incorporated (CCSI) for several years with the support of Tokyo Electric Power Company Inc. (TEPCO). The most recent phase of this program, which began in late 1997, is focused on the durability of catalytic reactors in the gas turbine combustor operating environment. This paper presents the results of subscale catalytic reactor endurance testing at simulated steady-state and cyclic operating conditions typical of utility gas turbine service. The results of full-scale, full-pressure, laboratory testing of a catalytic combustion system having the most advanced catalytic reactor mechanical design features developed by CCSI are also presented.

Combined Biomass and Black Liquor Gasifier/Gas Turbine Cogeneration at Pulp and Paper Mills

Kraft pulp and paper mills generate large quantities of black liquor and byproduct biomass suitable for gasification. These fuels are used today for onsite cogeneration of heat and power in boiler/steam turbine systems. Gasification technologies under development would enable these fuels to be used in gas turbines. This paper reports results of detailed full-load performance modeling of pulp-mill cogeneration systems, based on gasifier/gas turbine technologies and, for comparison, on conventional steam-turbine cogeneration technologies. Pressurized, oxygen-blown black liquor gasification, the most advanced of proposed commercial black liquor gasifier designs, is considered, together with three alternative biomass gasifier designs under commercial development (high-pressure air-blown, low-pressure air-blown, and low-pressure indirectly-heated). Heavy-duty industrial gas turbines of the 70-MWe and 25-MWe class are included in the analysis. Results indicate that gasification-based cogeneration with biomass-derived fuels would transform a typical pulp mill into a significant power exporter and would also offer possibilities for net reductions in emissions of carbon dioxide relative to present practice.

Development of a Catalytic Combustor for a Heavy-Duty Utility Gas Turbine

The most effective technologies currently available for controlling NOx emissions from heavy-duty industrial gas turbines are diluent injection in the combustor reaction zone, and lean premixed Dry Low NOx (DLN) combustion. For ultralow emissions requirements, these must be combined with selective catalytic reduction (SCR) DeNOx systems in the gas turbine exhaust. An alternative technology for achieving comparable emissions levels with the potential for lower capital investment and operating cost is catalytic combustion of lean premixed fuel and air within the gas turbine. The design of a catalytic combustion system using natural gas fuel has been prepared for the GE model MS9OO1E gas turbine. This machine has a turbine inlet temperature to the first rotating stage of over 1100°C and produces approximately 105 MW electrical output in simple cycle operation. The 508-mm-dia catalytic combustor designed for this gas turbine was operated at full-scale conditions in tests conducted in 1992 and 1994. The combustor was operated for twelve hours during the 1994 test and demonstrated very low NOx emissions from the catalytic reactor. The total exhaust NOx level was approximately 12–15 ppmv and was produced almost entirely in the preburner ahead of the reactor. A small quantity of steam injected into the preburner reduced the NOx emissions to 5–6 ppmv. Development of the combustion system has continued with the objectives of reducing CO and UHC emissions, understanding the parameters affecting reactor stability and spatial nonuniformities that were observed at low inlet temperature, and improving the structural integrity of the reactor system to a level required for commercial operation of gas turbines. Design modifications were completed and combustion hardware was fabricated for additional full-scale tests of the catalytic combustion system in March 1995 and January 1996. This paper presents a discussion of the combustor design, the catalytic reactor design, and the results of full-scale testing of the improved combustor at MS9OO1E cycle conditions in the March 1995 and January 1996 tests. Major improvements in performance were achieved with CO and UHC emissions of 10 ppmv and 0 ppmv at baseload conditions. This ongoing program will lead to two additional full-scale combustion system tests in 1996. The results of these tests will be available for discussion at the June 1996 Conference in Birmingham.

Conversion of a Heavy-Duty Industrial Gas Turbine to Combined Cycle

This paper discusses the evaluation, design, and operation of a combined-cycle plant for Bahamas Electricity Corporation in Nassau, Bahamas. The plant was designed to provide maximum fuel efficiency, satisfactorily operate to 40 percent load, and includes provisions for heavy oil firing in the gas turbine. The system was started up July, 1982 and has been in successful operation since then.

Heavy-Duty Gas Turbines-A Viable Marine Propulsion Option

Heavy-duty industrial gas turbines are suggested as an alternative propulsion plant to consider for ships, particularly ships of large displacement that are not volume limited. This paper examines the use of such a plant in a naval auxiliary, the Fast Combat Support Ship (AOE-1, Sacramento Class). The cycle discussed is of the combined gas turbine and steam cycle. The inlet to the compressor is supercharged and then intercooled, allowing the gas turbine to perform at significantly higher than rated power levels. Two controllable-pitch propellers at 50,000 shp each are used to drive the ship. Exhaust from the turbine is used to generate steam in an unfired waste-heat boiler. Reliability, maintainability, life-cycle costs and manning are addressed for comparison with the presently installed steam plant.