scholarly journals Catalytic Control of SI Engine Emissions Over Ion-Exchanged X-Zeolites

1997 ◽  
Author(s):  
Randip K. Das ◽  
B. B. Ghosh ◽  
Souvik Bhattacharyya ◽  
Maya DuttaGupta
Keyword(s):  
Noble Metals ◽  
Nox Reduction ◽  
Space Velocity ◽  
Back Pressure ◽  
Operating Conditions ◽  
Zeolite Catalysts ◽  
Si Engine ◽  
Nickel Metal ◽  
Wide Range ◽  
X Zeolite

Three catalysts based on X-zeolite have been developed by exchanging its Na+ ion with Copper, Iron and Nickel metal ions and tested in a SI engine exhaust for a wide range of exhaust and operating conditions. Of the three catalysts, the Cu-X catalyst exhibits the best NOx and CO conversion performance while Ni-X shows slightly better performance compared to the Fe-X catalyst at any catalyst temperature. Unlike noble metals, the doped X-zeolite catalysts, studied here, exhibit significant NOx reduction for a wide λ range and exhibit a slow rate of decrease with increase in λ ratio. Back pressure developed across the catalyst bed is found to be well-afford able and power loss due to back pressure is only 0.216% at space velocity of 52500 /h. During 30 hours of testing of each catalyst, no significant deactivation of any catalyst is observed.

Emission Control Through Cu-Exchanged X-Zeolite Catalysts: Experimental Studies and Theoretical Modeling

1999 ◽  
Vol 122 (1) ◽  
pp. 106-111
Author(s):  
S. Bhattacharyya ◽  
R. K. Das
Keyword(s):  
Mathematical Model ◽  
Noble Metals ◽  
Copper Ions ◽  
Nox Reduction ◽  
Experimental Studies ◽  
Back Pressure ◽  
Experimental Results ◽  
Zeolite Catalysts ◽  
Average Deviation ◽  
X Zeolite

Catalysts based on X-zeolite have been developed by exchanging its Na+ ion with Copper ions and its effectiveness in reducing NOx in an actual SI engine exhaust has been tested. Unlike noble metals, the doped X-zeolite catalysts, studied here, exhibit significant NOx reduction for a wide λ range and exhibit a slow rate of decrease with increase in λ ratio. Back pressure developed across the catalyst bed was found to be well-affordable and power loss due to back pressure is only minimal. During 30 hours of testing of the catalyst, no significant deactivation was observed. Additionally a mathematical model has been developed to predict the performance of the catalyst and to validate that against experimental results. Results predicted by the mathematical model agree well with the experimental results and absolute average deviation of experimental conversion efficiency is found to be less than 5 percent of the predicted value. [S0742-4795(00)01601-X]

Development of LP Blade Module for High Back Pressure-Aerodynamic Design

2017 ◽  
Author(s):  
Ambrish ◽  
Nand Kumar Singh
Keyword(s):  
Steam Turbine ◽  
Power Plants ◽  
Volume Flow Rate ◽  
Back Pressure ◽  
Operating Conditions ◽  
Total Efficiency ◽  
Aerodynamic Design ◽  
Streamline Curvature ◽  
Pressure Application ◽  
Wide Range

In steam turbine power plants, the appropriate design of the last stage blades is critical in determining the plant efficiency and reliability. The development of LP module for desert applications is finding applications for a number of industrial steam turbine operating with air cooled condensers. The conventional LP Module for water cooled condenser operates at low back pressure (Pexit = 0.09 bar) and are generally not suitable for high back pressure application. This paper focuses on the aerodynamic design & optimization of last stages of LP blade module for high back pressure application and validation through 3D CFD. The guide and moving blade are designed with seven equally-spaced profiles section from hub to shroud through Axstream S/w. The profile and incidence losses are minimized for the design and off-design conditions. Aeromechanical design of LP blade module consisting of 2 stages for 0.2 bar back pressure, 1.1 bar inlet static pressure and a mass flow of 61.2 kg/s is carried out. An optimization process through a streamline curvature code and design optimization software using Optimus is established and flow path contours is optimized thoroughly, a total to total efficiency of 81.4% is achieved for the rated condition. The off-design performance is investigated for a wide range of operating conditions, especially at low volume flow rate of steam condition.

Numerical study of pulverized coal-fired utility boiler over a wide range of operating conditions for in-furnace SO2/NOx reduction

2016 ◽  
Vol 94 ◽  
pp. 657-669 ◽  
Author(s):  
Srdjan Belošević ◽  
Ivan Tomanović ◽  
Nenad Crnomarković ◽  
Aleksandar Milićević ◽  
Dragan Tucaković
Keyword(s):  
Numerical Study ◽  
Nox Reduction ◽  
Pulverized Coal ◽  
Operating Conditions ◽  
Utility Boiler ◽  
Wide Range

Optimization of Design and Operational Parameters Using Genetic Algorithm for a Spark Ignition Engine With CNG/H2 Mixtures

2005 ◽  
Author(s):  
G. Anand ◽  
R. Balamurugan
Keyword(s):  
Genetic Algorithm ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Nox Emissions ◽  
Engine Fuel ◽  
Operational Parameters ◽  
Si Engine ◽  
Engine Efficiency ◽  
Wide Range

The present contribution describes the potential of using gaseous fuels like Hythane (CNG/H2 mixtures) as a spark ignition (SI) engine fuel. Genetic Algorithm (GA) is used to optimize the design and operational parameters of a CNG/H2 fueled spark ignition engine for maximizing the engine efficiency subjected to NOx emission constraint. This research deals with quasi-dimensional, two-zone thermodynamic simulation of four-stroke SI engine fueled with CNG/H2 blended fuel for the prediction of the combustion and emission characteristics. The validity of the model has been carried out by comparing the computed results with experimental data obtained under same engine setup and operating conditions. A wide range of engine parameters were optimized using a simple GA regarding both engine efficiency and NOx emissions. The five parameters chosen were compression ratio, engine speed, equivalence ratio, H2 fraction in the fuel, and spark plug position in cylinder head. The amount of NOx emissions was being kept under the constrained value of 750 ppm (< 5 g/kWh), which is less than permissible limit for heavy-duty engines.

Lean Blowout Limits and NOx Emissions of Turbulent, Lean Premixed, Hydrogen-Enriched Methane/Air Flames at High Pressure

2006 ◽  
Author(s):  
P. Griebel ◽  
E. Boschek ◽  
P. Jansohn
Keyword(s):  
High Pressure ◽  
Nox Reduction ◽  
Flame Temperature ◽  
Operating Conditions ◽  
Flame Stability ◽  
Nox Emissions ◽  
Lean Blowout ◽  
Wide Range ◽  
Pure Methane ◽  
Lean Premixed

Flame stability is a crucial issue in low NOx combustion systems operating at extremely lean conditions. Hydrogen enrichment seems to be a promising option to extend lean blowout limits of natural gas combustion. This experimental study addresses flame stability enhancement and NOx reduction in turbulent, high-pressure, lean premixed methane/air flames in a generic combustor, capable of a wide range of operating conditions. Lean blowout limits (LBO) and NOx emissions are presented for pressures up to 14 bars, bulk velocities in the range of 32–80 m/s, two different preheating temperatures (673 K, 773 K), and a range of fuel mixtures from pure methane to 20% H2/80% CH4 by volume. The influence of turbulence on LBO limits is discussed, too. In addition to the investigation of perfectly premixed H2-enriched flames, LBO and NOx are also discussed for hydrogen piloting. Experiments have revealed that a mixture of 20% hydrogen and 80% methane, by volume, can typically extend the lean blowout limit by roughly 10% compared to pure methane. The flame temperature at LBO is approximately 60 K lower resulting in the reduction of NOx concentration by ≈ 35% (0.5 → 0.3 ppm/15% O2).

Lean Blowout Limits and NOx Emissions of Turbulent, Lean Premixed, Hydrogen-Enriched Methane/Air Flames at High Pressure

2006 ◽  
Vol 129 (2) ◽  
pp. 404-410 ◽  
Author(s):  
P. Griebel ◽  
E. Boschek ◽  
P. Jansohn
Keyword(s):  
High Pressure ◽  
Nox Reduction ◽  
Flame Temperature ◽  
Operating Conditions ◽  
Flame Stability ◽  
Nox Emissions ◽  
Lean Blowout ◽  
Wide Range ◽  
Pure Methane ◽  
Lean Premixed

Flame stability is a crucial issue in low NOx combustion systems operating at extremely lean conditions. Hydrogen enrichment seems to be a promising option to extend lean blowout limits (LBO) of natural gas combustion. This experimental study addresses flame stability enhancement and NOx reduction in turbulent, high-pressure, lean premixed methane/air flames in a generic combustor capable of a wide range of operating conditions. Lean blowout limits and NOx emissions are presented for pressures up to 14bar, bulk velocities in the range of 32–80m∕s, two different preheating temperatures (673K, 773K), and a range of fuel mixtures from pure methane to 20% H2∕80%CH4 by volume. The influence of turbulence on LBO limits is also discussed. In addition to the investigation of perfectly premixed H2-enriched flames, LBO and NOx are also discussed for hydrogen piloting. Experiments have revealed that a mixture of 20% hydrogen and 80% methane, by volume, can typically extend the lean blowout limit by ∼10% compared to pure methane. The flame temperature at LBO is ∼60K lower resulting in the reduction of NOx concentration by ≈35%(0.5→0.3ppm∕15%O2).

Intrinsic Kinetics Study of CO Methanation on Ni-Mo-SiO2 Catalyst Prepared by Hydrothermal Method

2018 ◽  
Vol 921 ◽  
pp. 40-47
Author(s):  
Jia Ying Zhang
Keyword(s):  
Kinetic Model ◽  
Orthogonal Design ◽  
Fixed Bed ◽  
Reaction Network ◽  
Space Velocity ◽  
Operating Conditions ◽  
Least Square ◽  
Fixed Bed Reactor ◽  
Consecutive Reaction ◽  
Wide Range

A comprehensive kinetic model for methanation of syngas on Ni-Mo-SiO2catalyst was developed on a fixed bed reactor data. The CO and H2conversion, methane selectivity and yield were obtained in a wide range of operating conditions including 300 < T < 450°C, 1 < H2/CO <4 and 0.1 < P < 1.5 MPa with the total weight hourly space velocity (WHSV) of 60000 ml/h/g. A 6-step reaction scheme defined to the description of a reaction network that considers both catalytic and gas-phase as well as primary and consecutive reaction steps to predict the performance of the syngas methantion. Orthogonal design method was adopted to select test points with temperature, pressure and feed compositions as factors and the kinetic rates involved Langmuir – Hinshelwood equation kinetic model. The kinetic rate parameters were estimated using the Least Square Method by MATLAB. Comparing the experimental and model predicted data showed that presented model has a reasonable fit between the experimental data and the predicted values with average absolute relative deviation of ±9.8%.

Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

1972 ◽  
Vol 30 ◽  
pp. 596-597
Author(s):  
David A. Ansley
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Spatial Filter ◽  
Operating Conditions ◽  
Objective Lens ◽  
List Type ◽  
Spatial Filters ◽  
Transmission Electron ◽  
Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

Structure and properties of compact articles from high-alloyed iron powder with adding of boron nitride

2020 ◽  
pp. 39-48
Author(s):  
B. O. Bolshakov ◽  
◽  
R. F. Galiakbarov ◽  
A. M. Smyslov ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Grain Boundary ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Operating Conditions ◽  
Structure And Properties ◽  
Steam Turbines ◽  
Friction Forces ◽  
Wide Range

The results of the research of structure and properties of a composite compact from 13 Cr – 2 Мо and BN powders depending on the concentration of boron nitride are provided. It is shown that adding boron nitride in an amount of more than 2% by weight of the charge mixture leads to the formation of extended grain boundary porosity and finely dispersed BN layers in the structure, which provides a high level of wearing properties of the material. The effect of boron nitride concentration on physical and mechanical properties is determined. It was found that the introduction of a small amount of BN (up to 2 % by weight) into the compacts leads to an increase in plasticity, bending strength, and toughness by reducing the friction forces between the metal powder particles during pressing and a more complete grain boundary diffusion process during sintering. The formation of a regulated structure-phase composition of powder compacts of 13 Cr – 2 Mо – BN when the content of boron nitride changes in them allows us to provide the specified physical and mechanical properties in a wide range. The obtained results of studies of the physical and mechanical characteristics of the developed material allow us to reasonably choose the necessary composition of the powder compact for sealing structures of the flow part of steam turbines, depending on their operating conditions.

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