INLET FOGGING AND OVERSPRAY IMPACT ON INDUSTRIAL GAS TURBINE LIFE AND PERFORMANCE

LectureThe usage of an industrial inlet fogging and overspraying system on a 35,000 hp frame type industrial gas turbine in high pressure gas reinjection service was aimed to provide additional shaft power output and improved efficiency. However, operating experience has shown less than anticipated power increase and almost no efficiency change, while the gas turbines have experienced more rapid degradation. Consequently, a detailed study was undertaken to identify the principal degradation mechanisms and quantify their relative influence on the gas turbine’s performance and life reduction. This study included a field assessment; review and analysis of the installation and operating data from the historical trend monitoring system; inspection of a rotor for fouling, corrosion, and pitting; materials analysis of the fouling deposits, rotor surface pitting, and inlet filter media; review of the function and effects of inlet fogging and overspray; assessment of the effectiveness of the current on-line/ off-line compressor washing program and its compatibility with the overspraying operation; and an analysis of the overall gas turbine efficiency to determine levels of performance degradation. Results from Copyright © 2013 by Turbomachinery Laboratory, Texas A&M University this study identified the principal gas turbine degradation mechanisms, such as blade erosion, corrosion, fouling tip clearance widening, their causes, and their relative influence on the overall performance. For example, the study showed that the total power and efficiency degradation of the unit exceeded ten percent at the time of the rotor overhaul which is well above what is expected for this type of gas turbine. About 70 percent of this degradation was due to blade erosion and rotor clearance widening. These were attributed to the water overspray operation of the gas turbines. Surface fouling and pitting also contributed about 20 percent to the total performance degradation. For the given site conditions, the fogging and overspray system provided a gas turbine performance boost of approximately 2-5 percent in power and less than 0.5 percent in efficiency. Of this performance gain, saturation fogging accounted for about 85 percent, while overspray only provided 15 percent. The principal findings of this study showed that, while the fogging worked, the performance degradation due to water overspray negated most performance gains after only about 24,000 hours of operation. More detailed findings are included in the paper

Hydrodynamic Torque Converters for Oil & Gas Compression and Pumping Applications: Basic Principles, Performance Characteristics and Applications

TutorialTutorial 2

Gas Turbine Packaging Options And Features

TutorialThis tutorial provides an overview of typical packaging options for gas turbines in industrial applications. Applicable standards are discussed. The requirements for different systems, such as air filtration and fuel systems are explained. Off shore requirements, especially on floating systems are highlighted

Hydrodynamic Torque Converters For Oil & Gas Compression and Pumping Applications : Basic Principles, Performance Characteristics And Applications

TutorialHerrmann Foettinger as an alternative to a regular speed changing gear for shipboard propulsion. At that time, mechanical reduction gears for such high power applications were not available. The core idea of hydrodynamic torque converters and fluid couplings is to provide wear free power transmission using a hydraulic closed pump and turbine cycle. In the following decades, hydrodynamic torque converters experienced significant improvements driven by the automotive industry, and their use spread into various applications. Today, torque converters are commonly used in cars, busses, locomotives, construction equipment, and gas compression as a means of (i) smooth power transmission, (ii) to provide torque amplification during startup conditions, and (iii) to act as a damper for driver and driven equipment torsional disturbances and shock loads. In the oil and gas industry, torque converters are often used as integrated components in drive transmissions for electric motor driven compressors or pumps trains. They provide step-less speed variation along with progressive torque increase towards low speed. For example, torque converters and hydraulic couplings can be used to drive a variable speed centrifugal compressor using a fixed speed electric motor without the need for a variable frequency drive. In recent years, torque converters in combination with planetary gearboxes have been successfully demonstrated as a viable technology for variable speed electric motor driven centrifugal compressor applications. Torque converters are also used as soft starters between generators and gas or steam turbines. The unique power transmission features of the torque converter make it an option for equipment that requires start-up torque assistance and speed control. Modern torque converters up to 65,000 kW have been designed and are widely in operation

INLET FOGGING AND OVERSPRAY IMPACT ON INDUSTRIAL GAS TURBINE LIFE AND PERFORMANCE

LectureThe usage of an industrial inlet fogging and overspraying system on a 35,000 hp frame type industrial gas turbine in high pressure gas reinjection service was aimed to provide additional shaft power output and improved efficiency. However, operating experience has shown less than anticipated power increase and almost no efficiency change, while the gas turbines have experienced more rapid degradation. Consequently, a detailed study was undertaken to identify the principal degradation mechanisms and quantify their relative influence on the gas turbine’s performance and life reduction. This study included a field assessment; review and analysis of the installation and operating data from the historical trend monitoring system; inspection of a rotor for fouling, corrosion, and pitting; materials analysis of the fouling deposits, rotor surface pitting, and inlet filter media; review of the function and effects of inlet fogging and overspray; assessment of the effectiveness of the current on-line/ off-line compressor washing program and its compatibility with the overspraying operation; and an analysis of the overall gas turbine efficiency to determine levels of performance degradation. Results from Copyright © 2013 by Turbomachinery Laboratory, Texas A&M University this study identified the principal gas turbine degradation mechanisms, such as blade erosion, corrosion, fouling tip clearance widening, their causes, and their relative influence on the overall performance. For example, the study showed that the total power and efficiency degradation of the unit exceeded ten percent at the time of the rotor overhaul which is well above what is expected for this type of gas turbine. About 70 percent of this degradation was due to blade erosion and rotor clearance widening. These were attributed to the water overspray operation of the gas turbines. Surface fouling and pitting also contributed about 20 percent to the total performance degradation. For the given site conditions, the fogging and overspray system provided a gas turbine performance boost of approximately 2-5 percent in power and less than 0.5 percent in efficiency. Of this performance gain, saturation fogging accounted for about 85 percent, while overspray only provided 15 percent. The principal findings of this study showed that, while the fogging worked, the performance degradation due to water overspray negated most performance gains after only about 24,000 hours of operation. More detailed findings are included in the paper

egislation, maternal healthcare, fertility, female literacy, sanitation, violence against women and maternal deaths: a natural experiment in 32 Mexican states

Objective To test whether there is an association between abortion legislation and maternal mortality outcomes after controlling for other factors thought to influence maternal health. Design Population-based natural experiment. Setting and data sources Official maternal mortality data from 32 federal states of Mexico between 2002 and 2011. Main outcomes Maternal mortality ratio (MMR), MMR with any abortive outcome (MMRAO) and induced abortion mortality ratio (iAMR). Independent variables Abortion legislation grouped as less (n=18) or more permissive (n=14); constitutional amendment protecting the unborn (n=17); skilled attendance at birth; all-abortion hospitalisation ratio; low birth weight rate; contraceptive use; total fertility rates (TFR); clean water; sanitation; female literacy rate and intimate-partner violence

Turbomachinery for Refinery Applications

TutorialThis tutorial covers the basics, applications, and operation of compressors, expanders, steam turbines, and gas turbines in refinery applications. Modern refineries utilize a wide range of turbomachinery that must flexibly operate under harsh, fluid conditions with long life and minimal maintenance downtime. In refinery service, the fluids pose unique aerodynamic, materials, and structural design challenges including wet gas service, high gas path temperatures, and corrosive, flammable, and sometimes toxic service. These requirements make the design, packaging, controls, application, and operation of turbomachines in refineries highly complex and challenging. Operational and technical details of turbine and compression applications such as gas boost, refrigeration, hydrogen recycle, blow gas compression, coke gas compression, reformer recycle compression, steam turbine drivers, and gas turbine drivers will be discussed for refinery processes including alkylation, reforming, hydrocracking, fluid cracking, power generation, and gas boost. Topics cover refinery process fundamentals, turbomachines in refinery applications, design conditions, and -examples of special operational considerations in refinery service. A basic understanding of the processes as well as the type, power requirements, utilities, and application challenges of operating turbomachines in refineries is provided

TURBOMACHINERY FOR REFINERY APPLICATIONS

TutorialThis tutorial covers the basics, applications, and operation of compressors, expanders, steam turbines, and gas turbines in refinery applications. Modern refineries utilize a wide range of turbomachinery that must flexibly operate under harsh, fluid conditions with long life and minimal maintenance downtime. In refinery service, the fluids pose unique aerodynamic, materials, and structural design challenges including wet gas service, high gas path temperatures, and corrosive, flammable, and sometimes toxic service. These requirements make the design, packaging, controls, application, and operation of turbomachines in refineries highly complex and challenging. Operational and technical details of turbine and compression applications such as gas boost, refrigeration, hydrogen recycle, blow gas compression, coke gas compression, reformer recycle compression, steam turbine drivers, and gas turbine drivers will be discussed for refinery processes including alkylation, reforming, hydrocracking, fluid cracking, power generation, and gas boost. Topics cover refinery process fundamentals, turbomachines in refinery applications, design conditions, and -examples of special operational considerations in refinery service. A basic understanding of the processes as well as the type, power requirements, utilities, and application challenges of operating turbomachines in refineries is provided

Combined effects of time spent in physical activity, sedentary behaviors and sleep on obesity and cardio-metabolic health markers: a novel compositional data analysis approach

<div><p>The associations between time spent in sleep, sedentary behaviors (SB) and physical activity with health are usually studied without taking into account that time is finite during the day, so time spent in each of these behaviors are codependent. Therefore, little is known about the combined effect of time spent in sleep, SB and physical activity, that together constitute a composite whole, on obesity and cardio-metabolic health markers. Cross-sectional analysis of NHANES 2005–6 cycle on N = 1937 adults, was undertaken using a compositional analysis paradigm, which accounts for this intrinsic codependence. Time spent in SB, light intensity (LIPA) and moderate to vigorous activity (MVPA) was determined from accelerometry and combined with self-reported sleep time to obtain the 24 hour time budget composition. The distribution of time spent in sleep, SB, LIPA and MVPA is significantly associated with BMI, waist circumference, triglycerides, plasma glucose, plasma insulin (all p<0.001), and systolic (p<0.001) and diastolic blood pressure (p<0.003), but not HDL or LDL. Within the composition, the strongest positive effect is found for the proportion of time spent in MVPA. Strikingly, the effects of MVPA replacing another behavior and of MVPA being displaced by another behavior are asymmetric. For example, re-allocating 10 minutes of SB to MVPA was associated with a lower waist circumference by 0.001% but if 10 minutes of MVPA is displaced by SB this was associated with a 0.84% higher waist circumference. The proportion of time spent in LIPA and SB were detrimentally associated with obesity and cardiovascular disease markers, but the association with SB was stronger. For diabetes risk markers, replacing SB with LIPA was associated with more favorable outcomes. Time spent in MVPA is an important target for intervention and preventing transfer of time from LIPA to SB might lessen the negative effects of physical inactivity.</p></div

Pregnancy-Associated Hypertension in Glucose-Intolerant Pregnancy and Subsequent Metabolic Syndrome

To evaluate whether pregnancy-associated hypertension (preeclampsia or gestational hypertension), among women with varying degrees of glucose intolerance during pregnancy is associated with maternal metabolic syndrome 5-10 years later