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At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Emissions and performance of catalysts for gas turbine catalytic combustors

Three noble-metal monolithic catalysts were tested in a 12-centimeter diameter combustion test rig to obtain emissions and performance data at conditions simulating the operation of a catalytic combustor for an automotive gas turbine engine. Tests with one of the catalysts at 800 K inlet mixture temperature 300,000 pa (3 atm) pressure, and a reference velocity (catalyst bed inlet velocity) of 10 m/sec demonstrated greater than 99 percent combustion efficiency for reaction temperatures higher than 1300 K. With a reference velocity of 25 m/sec the reaction temperature required to achieve the same combustion efficiency increased to 1380 K. The exit temperature pattern factors for all three catalysts were below 0.1 when adiabatic reaction temperatures were higher than 1400 K. The highest pressure drop was 4.5 percent at 25 m/sec reference velocity. Nitrogen oxides emissions were less than 0.1 g NO2/kg fuel for all test conditions.

Anderson, D. N.↗
NASA NTRS1977

Catalytic combustion for the automotive gas turbine engine

Fuel injectors to provide a premixed prevaporized fuel-air mixture are studied. An evaluation of commercial catalysts was performed as part of a program leading to the demonstration of a low emissions combustor for an automotive gas turbine engine. At an inlet temperature of 800 K, a pressure of 500,000 Pa and a velocity of 20 m/s a multiple-jet injector produced less than + or - 10 percent variation in Jet-A fuel-air ratio and 100 percent varporization with less than 0.5 percent pressure drop. Fifteen catalytic reactors were tested with propane fuel at an inlet temperature of 800 K, a pressure of 300,000 Pa and inlet velocities of 10 to 25 m/s. Seven of the reactors had less than 2 percent pressure drop while meeting emissions goals of 13.6 gCO/kg fuel and 1.64 gHC/kg fuel at the velocities and exit temperatures required for operation in an automotive gas turbine engine. NO sub x emissions at all conditions were less than 0.5 ppm. All tests were performed with steady state conditions.

Anderson, D. N.↗
NASA NTRS1977

Emissions and performance of catalysts for gas turbine catalytic combustors

Three noble-metal monolithic catalysts were tested in a 12-cm-dia. combustion test rig to obtain emissions and performance data at conditions simulating the operation of a catalytic combustor for an automotive gas turbine engine. Tests with one of the catalysts at 800 K inlet mixture temperature, 3 x 10 to the 5th Pa pressure, and a reference velocity (catalyst bed inlet velocity) of 10 m/sec demonstrated greater than 99 percent combustion efficiency for reaction temperatures higher than 1300 K. With a reference velocity of 25 m/sec the reaction temperature required to achieve the same combustion-efficiency increased to 1380 K. The exit temperature pattern factors for all three catalysts were below 0.1 when adiabatic reaction temperatures were higher than 1400 K. The highest pressure drop was 4.5 percent at 25 m/sec reference velocity. Nitrogen oxides emissions were less than 0.1 g NO2/kg fuel for all test conditions.

Anderson, D. N.↗
NASA NTRS1977

Process of forming catalytic surfaces for wet oxidation reactions

A wet oxidation process was developed for oxidizing waste materials, comprising dissolved ruthenium salt in a reactant feed stream containing the waste materials. The feed stream is introduced into a reactor, and the reactor contents are then raised to an elevated temperature to effect deposition of a catalytic surface of ruthenium black on the interior walls of the reactor. The feed stream is then maintained in the reactor for a period of time sufficient to effect at least partial oxidation of the waste materials.

Jagow, R. B.↗
NASA NTRS1977

Experimental evaluation of premixing-prevaporizing fuel injection concepts for a gas turbine catalytic combustor

Experiments were performed to evolve and evaluate a premixing-prevaporizing fuel system to be used with a catalytic combustor for possible application in an automotive gas turbine. Spatial fuel distribution and degree of vaporization were measured using Jet A fuel. Three types of air blast injectors, an air assist nozzle and a simplex pressure atomizer were tested. Air swirlers with vane angles up to 30 deg were used to improve the spatial fuel distribution. The work was done in a 12-cm (4.75-in.) diameter tubular rig. Test conditions were: a pressure of 0.3 and 0.5 MPa (3 and 5 atm), inlet air temperatures up to 800 K (980 F), velocity of 20 m/sec (66 ft/sec) and fuel-air ratios of 0.01 and 0.025. Uniform spatial fuel distributions that were within plus or minus 10 percent of the mean were obtained. Complete vaporization of the fuel was achieved with air blast configurations at inlet air temperatures of 550 K (530 F) and higher. The total pressure loss was less than 0.5 percent for configurations without air swirlers and less than 1 percent for configurations with a 30 deg vane angle air swirler.

Tacina, R. R.↗
NASA NTRS1978

Effect of inlet temperature on the performance of a catalytic reactor

A 12 cm diameter by 15 cm long catalytic reactor was tested with No. 2 diesel fuel in a combustion test rig at inlet temperatures of 700, 800, 900, and 1000 K. Other test conditions included pressures of 3 and 6 x 10 to the 5th power Pa, reference velocities of 10, 15, and 20 m/s, and adiabatic combustion temperatures in the range 1100 to 1400 K. The combustion efficiency was calculated from measurements of carbon monoxide and unburned hydrocarbon emissions. Nitrogen oxide emissions and reactor pressure drop were also measured. At a reference velocity of 10 m/s, the CO and unburned hydrocarbons emissions, and, therefore, the combustion efficiency, were independent of inlet temperature. At an inlet temperature of 1000 K, they were independent of reference velocity. Nitrogen oxides emissions resulted from conversion of the small amount (135 ppm) of fuel-bound nitrogen in the fuel. Up to 90 percent conversion was observed with no apparent effect of any of the test variables. For typical gas turbine operating conditions, all three pollutants were below levels which would permit the most stringent proposed automotive emissions standards to be met.

Anderson, D. N.↗
NASA NTRS1977

Experimental evaluation of fuel preparation systems for an automotive gas turbine catalytic combustor

Premixing-prevaporizing fuel systems were evaluated for use with a catalytic reactor for possible automotive gas turbine application. Spatial fuel-air distributions, degree of vaporization, pressure drop and air velocity profiles were measured. Three airblast injectors and an air-assist nozzle were tested. Air swirlers were used to improve the spatial fuel-air distribution. The work was done in a 12 cm tubular duct. Test conditions were: a pressure of 0.3 and 0.5 MPa, inlet air temperatures up to 800 K, air velocities of 10 and 20 m/s and fuel-air ratios up to 0.020. The fuel was Jet A. The best results were obtained with an air-blast configuration that used multiple cones to provide high velocity air for atomization and also straightened the inlet airflow. With this configuration, uniform spatial fuel-air distributions were obtained with mixing lengths greater than 17.8 cm. In this length, vaporization of the fuel was 98.5 percent complete at an inlet air temperature of 700 K. The total pressure loss was 1.0 percent with a reference velocity of 20 m/s and 0.25 percent at 10 m/s. The air velocity was uniform across the duct and no autoignition reactions were observed.

Tacina, R. R.↗
NASA NTRS1978

Catalytic hydrosolvation process converts coal to low-sulfur liquid fuel

Development of the catalytic hydrosolvation process for converting coal to low-sulfur fuel oil is described in this paper. Coal impregnated with catalyst was slurried with oil, and the mixture was hydrogenated at a temperature of 475 C, and 30 min residence time under 3600 psi pressure. A ton of coal yielded 3.5 bbl of fuel oil containing 0.2% sulfur, with naphtha and C1-C4 hydrocarbon gases as byproducts. A preliminary economic evaluation of the process indicated potential for further development.

Qader, S. A.↗
NASA NTRS1979

Advanced low emissions catalytic combustor program at Pratt and Whitney

The feasibility of employing catalytic combustion technology to control the emissions of oxides of nitrogen for subsonic, stratospheric cruise aircraft operations is the objective of this NASA contract. The existing Enivornmental Protection Agency standards for the landing and takeoff cycle were also required to be satisfied. Work for the first phase of a proposed three phase effort is reported and is concerned with analytical design studies.

Sturgess, G. J.↗
NASA NTRS1979

Catalytic trimerization of aromatic nitriles and triaryl-s-triazine ring cross-linked high temperature resistant polymers and copolymers made thereby

Triazine compounds and cross-linked polymer compositions are made by heating aromatic nitriles to a temperature in the range of from about 100 C to about 700 C, and preferably in the range of from about 200 C to about 350 C, in the presence of a catalyst or mixture of catalysts selected from one or more of the following groups: (1) organic sulfonic and sulfinic acids, (2) organic phosphonic and phosphinic acids, and (3)metallic acetylacetonates, at a pressure in the range of from about atmospheric pressure to about 10,000 psi and preferably in the range of from about 200 psi to about 750 psi. Aromatic nitrile-modified (terminated and/or appended) imide, benzimidazole, imidazopyrrolone, quinoxaline, and other condensation type prepolymers or their precopolymers are made which are trimerized with or without a filler by the aforementioned catalytic trimerization process into triaryl-s-triazine ring containing or cross-linked polymeric or copolymeric products useful in applications requiring high thermal-oxidative stability and high performance structural properties at elevated temperatures.

Hsu, L. C.↗
NASA NTRS1978

Effect of inlet temperature on the performance of a catalytic reactor

A 12-cm-diameter by 15-cm-long catalytic reactor was tested with No. 2 diesel fuel in a combustion test rig at inlet temperatures of 700, 800, 900, and 1000 K. Other test conditions included pressures of 300,000 and 600,000 Pa, reference velocities of 10, 15, and 20 m/s, and adiabatic combustion temperatures in the range from 1100 to 1400 K. The combustion efficiency was calculated from measurements of carbon monoxide and unburned hydrocarbon emissions. Nitrogen oxide emissions and reactor pressure drop were also measured. At a reference velocity of 10 m/s, the CO and unburned hydrocarbons emissions and, therefore, the combustion efficiency were independent of inlet temperature. At an inlet temperature of 1000 K, they were independent of reference velocity. Nitrogen oxides emissions resulted from conversion of the small amount of fuel-bound nitrogen in the fuel. Up to 90% conversion was observed with no apparent effect of any of the test variables. For typical gas-turbine operating conditions, all three pollutants were below levels which would permit the most stringent proposed automotive emissions standards to be met.

Anderson, D. N.↗
NASA NTRS1978

Correlations of catalytic combustor performance parameters

A 12-cm-diameter catalytic combustor test rig using propane fuel at an inlet temperature of 800 K, a pressure of 300,000 Pa, and reference velocities from 10 to 20 m/s was studied. Combustion efficiency at the test conditions is a function of the catalyst bed cell density, cell circumference, reactor length, and the reference velocity; the efficiency was also dependent on the adiabatic reaction temperature to the tenth power. The percentage pressure drop is proportional to the reference velocity to the 1.5 power and is also proportional to the reactor length and inversely proportional to the cell hydraulic diameter, fractional open area, and the pressure. The minimum adiabatic reaction temperature required to meet the emissions goals is proportional to the reference velocity to the 0.1 power and inversely proportional to the cell circumference, cell density, and reactor length to the 0.1 power. The parameters which are a function of a catalyst factor are reported.

Bulzan, D. L.↗
NASA NTRS1980

Direct /TEM/ observation of the catalytic oxidation of amorphous carbon by Pd particles

The catalytic oxidation of amorphous carbon substrates by Pd particles is observed by in situ transmission electron microscopy. Various modes of selective attack of the carbon substrate in the immediate neighborhood of Pd particles are observed, which can be correlated with different degrees of particle mobility. Using amorphous substrates we have been able to demonstrate that the particle-substrate interaction is influenced by the structure of the particle. This has not previously been noted.

Moorhead, R. D.↗
NASA NTRS1980

Catalytic honeycomb combustor - Steady-state model and comparison with experiment

A steady-state lean combustion model for monolithic catalytic combustors is given. The model, consisting of several semi-global chemical reaction steps in the gas-phase and on the surface, is capable of analyzing CO and THC emissions. In the model computation presented, the influence of operating and design parameters on the minimum combustor length is studied. Special attention is given to the effect of after-bed gas-phase reaction space. Comparison with experimental data indicates good agreement in the range of parameters covered.

Tien, J. S.↗
NASA NTRS1980

Experimental evaluation of catalytic combustion with heat removal at near stoichiometric conditions

Two concentric tube configurations were tested. Tests were conducted at an inlet pressure of 150,000 Pa, inlet fuel air mixture temperatures from 780 to 960 K, combustion air flow rates from 0.78 to 1.5 g/s, equivalence ratios up to 0.90, and a range of cooling air flow rates. Propane and propylene fuels were used. Both configurations used air flowing through the center tube for cooling and combustion in the annulus on the catalytic surface. One configuration had the catalyst applied to the outside surface of the inner tube. Conversion of the fuel was very low for this configuration. The other configuration had the catalyst applied to the inside surface of the outer tube. Conversion of the fuel was considerably better in this configuration.

Bulzan, D. L.↗
NASA NTRS1981

Catalytic combustion with incompletely vaporized residual fuel

Catalytic combustion of fuel lean mixtures of incompletely vaporized residual fuel and air was investigated. The 7.6 cm diameter, graded cell reactor was constructed from zirconia spinel substrate and catalyzed with a noble metal catalyst. Streams of luminous particles exited the rector as a result of fuel deposition and carbonization on the substrate. Similar results were obtained with blends of No. 6 and No. 2 oil. Blends of shale residual oil and No. 2 oil resulted in stable operation. In shale oil blends the combustor performance degraded with a reduced degree of fuel vaporization. In tests performed with No. 2 oil a similar effect was observed.

Rosfjord, T. J.↗
NASA NTRS1983

Carbon Cloth Supports Catalytic Electrodes

Carbon cloth is starting material for promising new catalytic electrodes. Carbon-cloth electrodes are more efficient than sintered-carbon configuration previously used. Are also chemically stable and require less catalyst--an important economic advantage when catalyst is metal such as platinum.

Lu, W. T. P.↗
NASA NTRS1981

Determination of a kinetic region in catalytic oxidation of carbon monoxide

The catalytic activity of cupric oxide activated with ceric oxide in a braod interval of volumetric velocities was investigated. It was determined that for practical catalysts used in the diffuse region, dilution of the active substance by an inert diluent increases the effectiveness of the catalysts.

Sultanov, M. Y.↗