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Coal, Biomass and Alternative Fuels

1989;():V003T05A001. doi:10.1115/89-GT-106.
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A 1.8 kgs/sec (4 lbs/sec) bench-scale rich-quench-lean combustor has been successfully developed to burn micronized coal-water slurry (CWS) mixtures with 50% solids loading. Water quenching is used to freeze and shatter slag particles leaving the rich zone which are trapped and removed from the hot gas stream in a cyclone separator. Rich zone carbon burnout efficiencies in excess of 99% have been measured experimentally and are in good agreement with two-dimensional (2-D) coal combustion model predictions. Stable operation in the rich zone on 100% CWS at design conditions has been achieved. The low calorific value gas (125 to 445 Kcal/scm, 14 to 50 Btu/scf) produced in the quench zone, auto ignited in the lean zone at all conditions and self-sustained combustion was maintained without the need for auxiliary fuel. Low measured values of carbon monoxide (CO) and oxides of nitrogen (NOx) concentrations in the exhaust gases have demonstrated the ability of the combustor to control emissions to well within acceptable levels.

The bench-scale data provides a technology base for the design of a 15 kgs/sec (33 lbs/sec) combustor that will be used for testing of an advanced coal-fueled gas turbine engine.

Commentary by Dr. Valentin Fuster
1989;():V003T05A002. doi:10.1115/89-GT-111.
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A coal water slurry (CWS) air assist atomizer has been optimized for use in a coal fueled gas turbine engine. The nozzle is a refinement of a successful atomizer originally designed to operate at an atomizing air/fuel ratio of 1:1 and a pressure ratio of 2:1. Several configurations of the nozzle have been tested at atmospheric pressure conditions and scaled fuel flow rate using a CWS with 50% solids loading. The configurations studied included changes in air/liquid ratio, airflow split between inner and outer airflow paths, and geometry of the flow path. The data show that the optimized atomizer design can produce Sauter mean diameter (SMD) droplets of less than 50 microns at pressure ratios less than 3:1. The data also show that the lower limit on SMD is approximately 25 microns for the CWS tested.

Commentary by Dr. Valentin Fuster
1989;():V003T05A003. doi:10.1115/89-GT-115.
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A slagging combustor for a coal-fueled gas turbine engine is being developed. The work to date has been accomplished using a bench-scale combustor with one-tenth the heat input required for the full-scale gas turbine unit. The combustor features a fuel-rich slagging primary zone with hot refractory walls. Both single and multiple primary air/fuel injectors have been tested. Aerodynamic jet impaction on a target at one end of the primary zone removes much of the slag. The jet impaction is the result of the single air/fuel injector flow for multiple injectors, the intersection of the multiple jets forms a central jet. There is an additional particulate rejection impact separator between the primary and secondary zones to remove the slag that escapes the primary zone. Secondary air is introduced via multiple jets that rapidly mix with the incoming gas from the particulate removal device, resulting in a minimal formation of thermal NOx and the completion of the combustion process.

Variables that have been evaluated include coal-water mixture properties such as top and mean particle size, viscosity, loading and ash fusion temperature, and primary zone parameters such as volume, cross-sectional area, loading, and equivalence ratio.

Combustor performance was compared with single or multiple fuel injectors, relating the combustor performance to the spray characteristics of the two injector configurations. Modifications of the single injector were evaluated with the goal of attaining at least the same atomization performance as the smaller injectors used in the multiple injector configuration.

Flow visualization, computer modelling, and cold-flow velocity traverses have been employed to aid the development program. The results of the subscale development are being used to design and develop the full-size combustor for integration with the engine.

Commentary by Dr. Valentin Fuster
1989;():V003T05A004. doi:10.1115/89-GT-116.
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The objective of this effort is to establish the technology required for private sector use of an advanced coal-fueled gas turbine power system. The system is to burn low-cost, utility-grade coal, and yet comfortably meet the EPA New Source Performance Standard (NSPS) for coal-fired steam generators. Plant thermal efficiency is to surpass competing coal-utilization cycles.

Development of a successful high pressure slagging combustor is the key to meeting these objectives. As subcontractor to Westinghouse, Avco Research Laboratory/Textron (ARL) has designed and fabricated a subscale slagging combustor based on earlier MHD and boiler-type units. The new device is currently in a 12½-month developmental series of tests. Based on these series of tests, Westinghouse is to design, manufacture, and test a full-scale slagging combustor in a test cell at nominal field operating conditions. The activities described in this paper are sponsored by the Morgantown Energy Technology Center of the Department of Energy.

Topics: Combustion , Coal , Turbines
Commentary by Dr. Valentin Fuster
1989;():V003T05A005. doi:10.1115/89-GT-182.
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Experimental results obtained from cascades and one stage compressor performance tests before and after erosion were used to test a fault model to represent erosion. This model was implemented on a stage stacking program developed to demonstrate the effect of erosion in a multistage compressor. The effect of the individual stage erosion on the overall compressor performance is also demonstrated.

Commentary by Dr. Valentin Fuster
1989;():V003T05A006. doi:10.1115/89-GT-206.
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Deposition, erosion, and corrosion (DEC) experiments were conducted using three coal-water fuels (CWF) in a staged subscale turbine combustor operated at conditions of a recuperated turbine. This rich-quench-lean (RQL) combustor appears promising for reducing NOx levels to acceptable levels for future turbines operating with CWF. Specimens were exposed in two test sections to the combustion products from the RQL combustor. The gas and most surface temperatures in the first and second test sections represented temperatures in the first stators and rotors, respectively, of a recuperated turbine. The test results indicate deposition is affected substantially by gas temperature, surface temperature, and unburned carbon due to incomplete combustion.

The high rates of deposition observed at first stator conditions showed the need for additional tests to identify CWF coals with lower deposition tendencies and to explore deposition control measures such as hot gas cleanup.

Topics: Fuels , Coal , Gas turbines , Water
Commentary by Dr. Valentin Fuster
1989;():V003T05A007. doi:10.1115/89-GT-207.
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A staged, subscale turbine combustor based on a promising rich-quench-lean combustor approach to reduce NOX emissions was used to evaluate deposition, erosion, and corrosion (DEC) from coal-water fuels (CWF). This combustor was operated with three CWF at conditions of a recuperated turbine. Specimens were exposed in two test sections at temperature conditions of the first stator vanes and first rotor blades of the recuperated turbine. Resulting deposits were chemically analyzed. Deposit covered segments of specimens were placed in a furnace to extend their exposure to the potentially corrosive deposits.

The deposits produced at higher temperature first stator conditions differed significantly from those produced at lower temperature first rotor conditions. The rates of formation of the higher temperature deposits were high and the deposit chemistries were similar to the coal ash chemistry. The rates of formation of the lower temperature deposits were one to two orders of magnitude less and deposit chemistries were not the same as the coal ash chemistry. Some corrosion of a CoCrAlY coating was detected after a few hours of exposure in the DEC tests. Corrosion penetration up to one-half of the coating thickness was observed after an additional 460 hr furnace exposure. Much more testing is needed to explore whether the deposition and corrosion produced by the fuels evaluated are typical of this fuel form and to assess benefits of alternate turbine protection measures.

Commentary by Dr. Valentin Fuster
1989;():V003T05A008. doi:10.1115/89-GT-208.
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The results of an investigation of the particle dynamics and the blade erosion at the impact locations in radial turbine guide vanes are presented. The attention is focused in particular on the effect of inlet flow angle on the erosion of the blades, since the flow entering the guide vanes usually has an incidence angle due to the upstream scroll geometry. The total erosion per blade is calculated as a function of inlet flow angle for three different particle diameters which are 5, 15 and 60 microns respectively. According to the results of this investigation, for each particle size there is an inlet flow angle for minimum erosion of the guide vanes. This fact has to be accounted for in the design of the radial turbines operating in particulate flow environments.

Commentary by Dr. Valentin Fuster
1989;():V003T05A009. doi:10.1115/89-GT-223.
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A modified version of a commercially available General Electric MS7001E gas turbine has been successfully operated on synfuel derived from coal at the Cool Water Coal Gasification Program.

This paper addresses Cool Water’s experience with the MS7001E gas turbine in base load applications; starting and operating reliability; maintenance experience; modifications to the gas turbine including fuel delivery, combustion and control systems; and, future applications of advanced gas turbines in Integrated Coal Gasification Combined Cycle (IGCC) service.

Commentary by Dr. Valentin Fuster

Combustion and Fuels

1989;():V003T06A001. doi:10.1115/89-GT-247.
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In bibliography we can find many methods of determining pressure drop in the combustion chambers of gas turbines, but there is only very few data of experimental results.

This article presents the experimental investigations of pressure drop in the combustion chamber over a wide range of part-load performances (from minimal power up to take-off power). Our research was carried out on an aircraft gas turbine of small output. The experimental results have proved that relative pressure drop changes with respect to fuel flow over the whole range of operating conditions. The results were then compared with theoretical methods.

Commentary by Dr. Valentin Fuster
1989;():V003T06A002. doi:10.1115/89-GT-248.
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The coefficients of discharge of a number of angled chuted holes, typical of those currently used in the primary and dilution zones of some small reverse flow combustors, have been determined on a two dimensional rig. Also evaluated were two types of “low cost” angled chuted holes. The paper describes the test rig, the geometry of the holes, the coefficient of discharge data, the sensitivity of the data to certain features and makes comparisons of the data with those for plain and plunged holes.

Commentary by Dr. Valentin Fuster
1989;():V003T06A003. doi:10.1115/89-GT-249.
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The primary zone of the reverse flow combustors for helicopters tested at ONERA is fed with air from primary holes, multiples holes for the wall cooling and prevaporiser tubes.

The effect of the primary holes on the combustor performances has been studied.

Gas sampling inside the combustor has been achieved in order to understand the flow mechanisms with and without primary holes. The differences observed on the 2 configurations are not significant. Air from the prevaporiser tubes and from the wall cooling is sufficient for the air feeding of the primary zone.

Commentary by Dr. Valentin Fuster
1989;():V003T06A004. doi:10.1115/89-GT-250.
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The TP 500 is a 525 SHP turboprop engine being produced by Teledyne Continental Motors for general aviation use.

This paper describes the design and performance of the reverse flow fan spray combustion system being supplied for this engine. The main features of the design are described in some detail, together with the performance of the system as established in the combustion test facility at AIT Ltd and covering light-up to Take-Off conditions and sea level to 6km altitude.

Commentary by Dr. Valentin Fuster
1989;():V003T06A005. doi:10.1115/89-GT-251.
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Rapid advances in available computer technology in the past ten years coupled with the ever increasing costs associated with gas turbine combustor development testing led to considerable interest in the development of sophisticated numerical methods for the design and analysis of turbine engine combustors. The development and refinement of these methods has been taking place at GE Aircraft Engines since 1980 as part of an ongoing research and development project. Efforts associated with this project have achieved considerable progress to date, including the development of 2D/axisymmetric and full 3D versions of an improved elliptic numerical model (CONCERT), suitable for application to combustor related flow problems. The application of CONCERT to typical combustor performance problems has demonstrated its capabilities to provide useful and accurate design information resulting in less dependence on component testing. This has resulted in engineering productivity improvement and reduced costs associated with combustor performance development.

Commentary by Dr. Valentin Fuster
1989;():V003T06A006. doi:10.1115/89-GT-252.
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Since 1982, the Department of Energy (DOE), through the Morgantown Energy Technology Center (METC), has been conducting research for the purpose of verifying the feasibility of using coal fuels in heat engine applications. The heat engines of primary concern are the gas turbine and the diesel engine. The overall program objective is to develop the technology base for an environmentally sound, integrated heat engine system which will produce cost-competitive energy from coal. During the past 2 years the major emphasis of the gas turbine development program has been the coal-fueled combustors. This paper will review the current progress on coal-fueled gas turbine combustor development.

Commentary by Dr. Valentin Fuster
1989;():V003T06A007. doi:10.1115/89-GT-253.
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Steam injection tests have been carried out on Ruston TB5000 and Tornado gas turbines. Steam was injected into the primary zone of the combustion chambers and the centre casings of both engines. Both engines were operated in twin shaft mode and the Tornado also in single shaft mode. The engines have been characterised for performance, emissions and combustion stability. Operational criteria have been defined and the thermodynamic changes in the cycle requiring modification in control parameters, during steam injection, have been identified.

Topics: Engines , Steam
Commentary by Dr. Valentin Fuster
1989;():V003T06A008. doi:10.1115/89-GT-254.
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National standards for NOx control for gas turbines are being evaluated and modified throughout the world. These standards are often supplemented by local or site specific emission limits. The numeric value of any emission limit is influenced by both the local environmental conditions, and, importantly, by the actual NOx removal capacity of the specific technologies that can be applied to the processes and equipment that will be governed by the emission standards. That is, emission limits can not be so restrictive that there is no technology available that can be applied to meet the permit condition. However, as new technologies are developed to meet the ever increasingly restrictive emission limitations, they become the standard by which the next round of emission limit setting is guided.

Current NOx control technologies for gas turbine applications employ fuel switching to a low nitrogen content fuel, wet combustion control (steam or water injection into the combustor), or exhaust gas treatment (selective catalytic reduction technology) or combinations of those controls.

Recently, dry combustion controls have been, or are being, developed by the gas turbine manufacturers, and catalytic combustion control processes are being researched. This paper presents a brief overview of the national NOx emission requirements of Europe, Japan, and the United States. A discussion of the new dry, low NOx controls presently emerging in the electric utility, gas turbine market are then reviewed, with an emphasis on the commercial applications and typical operating results that have been experienced.

In this paper, all NOx values are referenced to dry, 15% oxygen exhaust conditions unless otherwise stated. The units are volumetric, in parts per million (ppm), unless otherwise stated.

Commentary by Dr. Valentin Fuster
1989;():V003T06A009. doi:10.1115/89-GT-255.
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Controls for emissions of oxides of nitrogen were first required for gas turbines by the Los Angeles County Air Pollution Control District (LAAPCD) and the San Diego Air Pollution Control District (SDAPCD) in the early 1970’s. To achieve the necessary control, water was injected into the combustor flame zone to reduce flame temperature. The consequent reduction in NOx amounted to about forty percent when half as much water as fuel was injected into the reaction zone. The emissions level achieved was approximately 75 ppmvd (parts per million by volume dry) on oil fuel as required by SDAPCD Rule 68, and with the airflow of these MS5000 machines at about 950,000 lbm/hr, this corresponded to 140 lbm/hr of NO2 when expressed at 15% O2 as required by LAAPCD Rule 67. Hilt and Waslo, (Ref. 1) and Hilt, et al (Ref. 2, 3) provide summary discussions of this work.

Commentary by Dr. Valentin Fuster
1989;():V003T06A010. doi:10.1115/89-GT-256.
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Gaseous fuels such as landfill gas contain significant quantities of inerts, typically CO2 and N2. This can lead to difficulties in predicting the emission and thermodynamic performance of industrial gas turbines. An algorithm has been developed to predict emissions of NOx for known quantities of inerts and effects on performance quantified. The effect of steam injection is compared to that of inerts and a relationship established.

Topics: Engines , Emissions
Commentary by Dr. Valentin Fuster
1989;():V003T06A011. doi:10.1115/89-GT-257.
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Dow Chemical, U. S. A., is currently operating two Westinghouse W501D5 combustion turbines with synthetic gas from the commercial demonstration coal gasification unit at Plaquemine, Louisiana.

The first of these units was fueled with synthetic gas in April 1987. This conversion followed several years of experimentation and prototype work by Dow and Westinghouse. The second unit began operating with synthetic gas during September 1987.

Addition of synthetic gas capability to these combustion turbines, originally installed in December 1982 and May 1983, was relatively straightforward, and once installed, did not adversely affect their operation or efficiency on natural gas, or mixtures in various proportions with synthetic gas. For durability assessment, special instrumentation was maintained at the site in the months immediately following conversion. This facilitated making minor changes to improve combustor longevity.

The heat recovery units were modified for synthetic gas operation to improve corrosion resistance and to handle higher temperatures. Minor adjustments were made in the controls to accommodate changing gas flow. Emission monitoring was enhanced.

Topics: Combustion , Coal , Turbines
Commentary by Dr. Valentin Fuster
1989;():V003T06A012. doi:10.1115/89-GT-261.
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The influence of fuel composition on soot emissions from continuous flow combustors is examined. A study of the combustion characteristics of a wide range of present and potential aviation fuels suggests that smoke point provides a better indication of sooting tendency than does hydrogen content. It is concluded from this study that the best empirical relationship between fuel chemical composition and soot emissions is one which combines two fuel composition parameters — smoke point and naphthalene content — into a single parameter which is shown to correlate successfully soot emissions data acquired from several different fuels burning in a variety of gas turbine and model combustors.

Commentary by Dr. Valentin Fuster
1989;():V003T06A013. doi:10.1115/89-GT-262.
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Measurements of nitric oxide emissions are carried out on a continuous flow combustor when operating over wide ranges of fuel/air ratio at pressures up to 1.52 MPa (15 atmos). Fuel is supplied to the flame zone from a circular array of 30 equispaced miniature airblast atomizers which is incorporated into a perforated-plate flameholder. Standard instrumentation and sampling techniques are used to measure pollutant emissions over wide ranges of mean fuel drop size. The results obtained with several selected fuels demonstrate the effects of variations in fuel composition, fuel drop size, and combustor operating conditions on nitric oxide emissions.

Topics: Fuels , Sprays
Commentary by Dr. Valentin Fuster
1989;():V003T06A014. doi:10.1115/89-GT-263.
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In the present paper, two-phase interaction inside pre filming airblast atomizer and its influence on atomization are studied. Liquid film wave inside the atomizer is measured with techniques called resistance method and optics method, which are also developed herein. By the means of laser pulse micrography, high speed photography and laser particle sizer, disintegration and fluctuation of liquid wave are picturized and spray size SMD and size distribution parameter N are measured. Experiments show that liquid wave inside atomizer has important influence on spray characteristics.

Topics: Waves , Liquid films
Commentary by Dr. Valentin Fuster
1989;():V003T06A015. doi:10.1115/89-GT-264.
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Rig testing of a lean-premixed, liquid-fueled corabustor was conducted to establish the feasibility of achieving ultra-low NOx emissions at typical gas turbine operating conditions. Two different filming fuel injector concepts were evaluated.

The majority of combustor testing was conducted using No. 2 diesel. The test results showed 12 and 20 ppm NOx at 6 and 9 atm, respectively. Corresponding CO levels were 50 ppm in both cases.

Commentary by Dr. Valentin Fuster
1989;():V003T06A016. doi:10.1115/89-GT-265.
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As described previously in ASME papers, an effort has been underway to apply catalytic combustion for small gas turbines. To improve combustion efficiency at the engine operating conditions, two catalytic combustors have been developed. Both combustors showed high combustion efficiency and low NOx emissions in combustor rig tests. In engine tests, Type A combustor achieved the NOx goal of 15 ppmv as corrected to 5 percent oxygen (5.6 ppmv at 15 percent oxygen) for base load operation. Combustion efficiency was greater than 98 percent for the fresh catalyst, however, it decreased rapidly with catalyst deactivation.

Commentary by Dr. Valentin Fuster
1989;():V003T06A017. doi:10.1115/89-GT-266.
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The initial development of a lean-premixed, natural gas-fired combustor for a 200 kw gas turbine is described. The development effort included both rig testing and on-engine testing of the combustor. The combustor demonstrated an ultra-low NOx emissions capability in both test environments.

Commentary by Dr. Valentin Fuster
1989;():V003T06A018. doi:10.1115/89-GT-268.
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More than 100 different fuels have been examined for the influence of their properties on pollutant levels, using two different combustors. Comparison with data from other sources is attempted. Some simple correlations are suggested.

Commentary by Dr. Valentin Fuster
1989;():V003T06A019. doi:10.1115/89-GT-273.
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The present work reports an experimental study of the effect of swirl on the dynamic behavior of drops and on the velocity and turbulence fields of an isothermal spray using a two-component Phase Doppler Particle Analyzer (PDPA). It represents the first phase of an effort to investigate the effect of swirl on the structure of liquid spray flames, the stability of the flame, and its effect on the emission of pollutants. A vane type swirler was placed on the liquid supply tube of a pressure atomizer and tested in the wind tunnel under specified conditions. Mean velocity and turbulence properties were obtained for the gas phase. In addition, drop velocity and drop size distributions, particle number densities, and volume flux were measured at different locations within the swirling flow. Large differences in the spatial distribution of the drops over its size, velocity, and number density are observed when the spray in a co-flowing air with the same axial velocity is compared with the atomizer spraying into the swirling flow field. Large drops seem to be recirculated into the core of the swirling flow, while rather small drops surround this central region. The radial distribution of particle number density and liquid volume flux are also different when the atomizer spraying into the co-flowing air and into the swirling field are compared. Particle number densities for the latter exhibit higher peak values close to the nozzle but show almost the same peak values as the quiescent spray but at different radial location further downstream. The velocity of specific drop sizes was also obtained. Drops as large as 5 μm are seen to follow closely the mean velocity of the gas. The turbulence properties of the swirling flow show significant influence on the dynamic behavior of the drops. Radial distribution of turbulence kinetic energy, normal Reynolds stresses, and Reynolds shear stresses exhibit double peak values which delineate the boundaries of the central recirculation region and the external free stream. Within these boundaries the radial distribution of both particle number density and volume flux are seen to attain their maximum values.

Topics: Turbulence , Sprays
Commentary by Dr. Valentin Fuster
1989;():V003T06A020. doi:10.1115/89-GT-277.
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A description is given of a simple, prototype, pulse, pressure-gain, combustor for a gas turbine. The work reported was targeted at alleviating problems previously observed with the prototype combustor. These were related to irreversibilities, causing a performance deficiency, in the secondary flow passage. The work consisted of investigating experimentally the effect of tuning the secondary-flow path-length, adding a flow restrictor at the combining-cone entry station and redesigning the combining-cone itself. The overall result was to eradicate the previously noted performance deficiency thereby increasing the maximum pressure-gain obtained in the gas turbine from 1.6% to 4.0% of the compressor absolute delivery pressure.

Commentary by Dr. Valentin Fuster
1989;():V003T06A021. doi:10.1115/89-GT-288.
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A systematic study of soot formation along the centerlines of axisymmetric laminar diffusion flames of a large number of liquid hydrocarbons, hydrocarbon blends, and aviation turbine and diesel fuels were made. Measurements of the attenuation of a laser beam across the flame diameter were used to obtain the soot volume fraction, assuming Rayleigh extinction. Two sets of hydrocarbon blends were designed such that the molecular fuel composition varied considerably but the temperature fields in the flames were kept practically constant. Thus it was possible to separate the effects of molecular structure and the flame temperature on soot formation. It was quantitatively shown that the smoke point height is a lumped measure of fuel molecular constitution. The developed empirical relationship between soot volume fractions and fuel smoke point and hydrogen to carbon ratio was applied to five different combustor radiation data, and good agreement was obtained.

Commentary by Dr. Valentin Fuster
1989;():V003T06A022. doi:10.1115/89-GT-292.
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Measurements have been made on a fully annular test facility, downstream of a row of heated dilution jets injected normally into a confined cross-flow at a momentum flux ratio of 4. The investigation concentrated on the consistency of mixing between the jets, as indicated by the regularity of the temperature pattern around the cross-flow annulus. When the heated air was supplied from a representative feed annulus, the exit velocity profile across each plunged hole was significantly altered and caused a distortion of the temperature distribution in the ensuing jet. The degree of distortion varies in a random manner, so that each jet has its own mixing characteristics thereby producing irregularity of the temperature pattern around the annulus. With the same approach and operating conditions some of the plunged dilution holes were modified, and tests on this modified sector indicated a significant improvement in the circumferential regularity of the temperature pattern. Further tests showed these modifications to the dilution holes had a negligible effect on the values of the discharge coefficients.

Commentary by Dr. Valentin Fuster
1989;():V003T06A023. doi:10.1115/89-GT-303.
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Current trends in liquid-fueled practical combustion systems are leaving less tolerance for fuel injection deficiencies such as poor spray field symmetry. The present paper evaluates the symmetry of the flowfield produced by a practical air-blast atomizer. Specifically, the influence of both the continuous phase and dispersed phase on the sprayfield symmetry is assessed. In the present case, asymmetry in volume flux is associated principally with disparities in the injection of the dispersed phase, which is manifested by a maldistribution of larger drops. Asymmetries observed in the continuous phase without the dispersed phase are reduced in magnitude by the presence of the dispersed phase, but still contribute to asymmetry in radial spread of the dispersed phase.

Commentary by Dr. Valentin Fuster
1989;():V003T06A024. doi:10.1115/89-GT-322.
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Curved blade radial swirlers using all the primary air were investigated with applications to lean burning gas turbine combustor primary zones with low NOx emissions. Two modes of fuel injection were compared, central and radial swirler pássage injection for gaseous and liquid fuels. Both fuel systems produced low NOx emissions but the upstream mixing in the swirler passages resulted in ultra low NOx emissions. A 140mm diameter atmospheric pressure combustor was used with 43% of the combustor air flow into the primary zone through the radial swirler. Radial gas composition measurements at various axial distances were made and these showed that the flame stability and NOx emissions were controlled by differences in local mixing at the base of the swirling shear layer downstream of the swirler outlet. For radial passage fuel injection it was found that a very high combustion efficiency was obtained for both propane and liquid fuels at 400K and 600K inlet temperatures. The flame stability, although worse than for central fuel injection was considerably better than for a premixed system. The NOx emissions at one bar pressure and 600K inlet temperature, compatible with a high combustion efficiency, for propane and kerosene were 3 and 6 ppm at 15% oxygen. For Gas Oil the NOx emissions were higher, but were still very low at 12ppm. Assuming a square root dependence of NOx on pressure these results indicate that NOx emissions of 48ppm for Gas Oil and less than 12ppm for gaseous fuels could be achieved at 16 bar pressure, which is typical of recent industrial gas turbines. High air flow radial swirlers with passage fuel injection have the potential for a dry solution to the NOx emissions regulations.

Commentary by Dr. Valentin Fuster

Oil and Gas Applications

1989;():V003T07A001. doi:10.1115/89-GT-3.
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A preliminary design for a Dresser-Rand DC990 industrial gas turbine engine modified for intercooling and recuperation (ICR) is presented. The DC990 was selected because its configuration is amenable to intercooling and because it is in the power range of interest. Based upon preliminary estimates, engine power output will increase from 6000 bhp to 8400 bhp at design point. Design point specific fuel consumption will be reduced 26% to a heat rate of 6300 BTU/bhp-hr. Moreover, the DC990 ICR engine maintains a high thermal efficiency during part-load operation. These performance improvements are achievable using proven, low-risk technology. The resulting combination of low fuel consumption and low maintenance costs makes the DC990 ICR gas turbine engine an attractive engine package for several applications.

Topics: Gas turbines
Commentary by Dr. Valentin Fuster
1989;():V003T07A002. doi:10.1115/89-GT-8.
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This paper describes the upgrade of a GE Frame 3 industrial gas turbine with new advanced technology parts and a new microprocessor-based control system. Based on pre- and post-upgrade performance tests, the gas turbine heat rate was reduced by 9.4%. In addition, with the new triple redundant control system and upgraded hardware, unit availability is anticipated to improve by 18% over the extended life of the gas turbine. The paper describes the mechanical and control changes and the method used to measure the enhancement of unit performance.

Commentary by Dr. Valentin Fuster
1989;():V003T07A003. doi:10.1115/89-GT-9.
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In 1978, Shell Canada Limited commissioned a large aero-derivative gas turbine driven compressor unit in its Waterton Straddle Plant. This unspared unit provides the primary recompression service in the “Deep Cut” ethane extraction facility. Significant operating features of this unit include flat rating and three stages of waste heat recovery from the turbine exhaust.

Throughout its history, this unit has demonstrated over 99% reliability and has operated for long periods without significant maintenance. All routine turbine maintenance has been accomplished on-site.

This paper describes the features of the installation, the operating and maintenance philosophy, and the experience obtained from ten years’ service, thus providing the reader with insight in regard to features and practices which can provide for a successful installation.

Topics: Gas turbines , Trains
Commentary by Dr. Valentin Fuster
1989;():V003T07A004. doi:10.1115/89-GT-23.
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Over the past few years, there has been accelerated development in predictive maintenance techniques such as condition monitoring. This paper describes the development of a condition monitoring system which monitors gas compression equipment for a major gas transmission company. A stand-alone system, featuring a data collector and PC-based software, was implemented first to allow for medium to longer-term trending. Subsequently, an on-line system has been developed to facilitate automatic acquisition of data and enhanced monitoring capabilities. Various diagnostic techniques have been included in both the stand-alone and on-line systems to aid in data interpretation and analysis.

Commentary by Dr. Valentin Fuster
1989;():V003T07A005. doi:10.1115/89-GT-71.
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This paper describes and discusses techniques which can effectively diagnose dynamics problems in turbomachinery. A variety of elusive dynamics problems are identified which require definition, quantification, diagnosis, and monitoring. The state of the art in measurement and signal processing techniques is discussed with reference to such factors as the directness of the measurement, the degree of intrusion required, the difficulty of installation, and the reliability or durability of the sensor. Several examples of techniques are provided which have proved to be effective in diagnosing elusive dynamics problems; some examples allow comparison of alternative techniques with different degrees of effectiveness. Problems addressed include rotating stall in the compressor section of a gas turbine, coupled lateral/torsional vibration in a gas turbine driven pipeline compressor, forced vibration of combustor parts, strain gage telemetry of blade vibrations, and nonintrusive measurement of blade vibrations using bearing mounted accelerometers.

Commentary by Dr. Valentin Fuster
1989;():V003T07A006. doi:10.1115/89-GT-91.
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Compressor washing is a common gas turbine maintenance task. This paper presents results from field surveys of gas turbine users, manufacturers, and washing agent suppliers. These surveys were conducted to assess current washing practices and needs for various user applications. Plans for field testing to evaluate performance and effectiveness of on-line washing are also presented.

Topics: Compressors
Commentary by Dr. Valentin Fuster
1989;():V003T07A007. doi:10.1115/89-GT-93.
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Frequency domain analysis is presented to define susceptibility of complex pumping systems to surge oscillations. In the analysis, piping spans are considered as distributed elements, compressors or pumps, orifices, valves, and junctions as lumped acoustic four pole elements. The piping elements are connected into one network through the use of appropriate matching boundary conditions. The analysis is most readily applicable to single stage units, typical of gas transmission stations. The surge model is based on predicting damping (logarithmic decrement values) and mode shapes for pressure and flow pulsations of the interactive dynamic system at its various natural acoustic frequencies. The system design is optimized by assuring that all operating points are sufficiently removed from surge, i.e., logarithmic decrements are above certain specified value. The effects of mean flow on acoustic wave propagation, pipe friction, viscothermal dissipation, and pressure losses at various piping locations (junctions, valves, orifices) are accounted for in the model. Results of the computational modeling of a complex centrifugal compressor system is presented. The analytical model is also verified by comparing the analytical results with experimental data.

Topics: Damping , Surges
Commentary by Dr. Valentin Fuster
1989;():V003T07A008. doi:10.1115/89-GT-109.
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Centrifugal pipeline compressors are often restaged to meet new operating requirements. Several examples of compressor revamps are presented to illustrate various factors which can influence these restaging efforts. Examples involving both single-stage and multi-stage compressors are included. Various types of modern impeller designs used in pipeline revamps are discussed. An explanation is given of the boundaries which define a typical pipeline compressor range chart.

Commentary by Dr. Valentin Fuster
1989;():V003T07A009. doi:10.1115/89-GT-222.
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Mechanical dry gas seal systems were retrofitted into two centrifugal natural gas compressors which are located offshore in the Norwegian sector of the North Sea.

The project was initiated after a fire and several gas explosions had occurred in the gas turbine lube oil reservoir. These incidents were a result of gas leaking from the compressor’s seal oil system and then migrating via the lube oil lines into the reservoir.

The dry gas seal systems have eliminated gas leakage into the turbine lube oil reservoir, eliminating the hazard of gas explosion. The retrofits have also provided additional benefits including reductions in space and weight, reduced power usage, reduced maintenance, and elimination of seal oil consumption which had been up to 440 gal./day (2000 liters/day).

Commentary by Dr. Valentin Fuster
1989;():V003T07A010. doi:10.1115/89-GT-225.
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The design and development of a new generation of an economical 500 kW turboexpander/generator is presented. This paper briefly discusses current pressure reduction power recovery applications and describes in detail major steps in the development of this new 500 kW turboexpander/generator.

Topics: Design
Commentary by Dr. Valentin Fuster

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