Thermal decomposition of 1,2-dichlorobenzene part I: Effect of operating conditions

The selective catalytic reduction (SCR) methodology is notably recognized as the widely applied strategy for NOX control in exhaust after-treatment technologies. In real SCR systems, complex unsteady turbulent multi-phase flow phenomena including poly-dispersed AdBlue® spray evolve with a wide ranging relative velocity between the droplet phase and carrier gas phase. This results from an AdBlue® spray that is injected into a mixing pipe which is cross-flowing by a hot exhaust gas. To reduce the complexity while gaining early information on the injected droplet size and velocity needed for a minimum deposition and optimal conversion, a single droplet with a specified diameter is addressed to mimic a spray featuring the same Sauter Mean Diameter. For that purpose, effects of turbulent hot cross-flow on thermal decomposition processes of a single AdBlue® droplet are numerically investigated. Thereby, a single AdBlue® droplet is injected into a hot cross-flowing stream within a mixing pipe in which it may experience phase change processes including interaction with the pipe wall along with liquid wall–film and possible solid deposit formation. First of all, the prediction capability of the multi-component evaporation model and thermal decomposition is evaluated against the detailed simulation results for standing droplet case for which experimental data is not available. Next, exploiting Large Eddy Simulation features the effect of hot turbulent co- and cross-flowing streams on the dynamic droplet characteristics and on the droplet/wall interaction is analyzed for various droplet diameters and operating conditions. This impact is highlighted in terms of droplet evaporation time, decomposition efficiency, droplet trajectories and wall–film formation. It turns out that smaller AdBlue® droplet diameter, higher gas temperature and relative velocity lead to shorter droplet life time as the droplet evaporates faster. Under such conditions, possible droplet/wall interaction processes on the pipe wall or at the entrance front of the monolith may be avoided. Since the ammonia (NH3) gas generated by urea decomposition is intended to reduce NOX emission in the SCR system, it is apparent for the prediction of high NOX removal performance that UWS injector system which allows to realize such operating conditions is favorable to support high conversion efficiency of urea into NH3.

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Research on the Thermal Decomposition Process of K-Feldspar-CaSO4-CaO System

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.734-737.916 ◽

2013 ◽

Vol 734-737 ◽

pp. 916-920 ◽

Cited By ~ 1

Author(s):

Jing Xia Chao ◽

Ju Pei Xia ◽

Chao Qin Yang ◽

Zhao Shu Zhang ◽

Xue Jiao Ren

Keyword(s):

Thermal Decomposition ◽

Calcium Sulfate ◽

Xrd Analysis ◽

Operating Conditions ◽

Decomposition Process ◽

Complex Reaction ◽

X Ray Diffraction ◽

Thermal Decomposition Process ◽

X Ray

The thermal decomposition process of K-feldspar-CaSO4-CaO system was studied by X-ray diffraction (XRD) analysis of the product which calcined at 1473K. The results show that KAlSi3O8 firstly is decomposed into KAlSi2O6 and released the SiO2, then has a complex reaction between KAlSi2O6 and CaO, which generated intermediates-K2SiO3 under the operating conditions. K2SiO3 is unstable and reacted with calcium sulfate to generate K2SO4. When the CaO amount is insufficient, the main products are KAlSi2O6 and 2CaOAl2O3SiO2, the potassium existed as K2S2O8; when n (CaO) / n (KAS6) 12:1, the products will further transfer into CaOSiO2 and 2CaO SiO2 and the potassium existed as K2SO4.

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Modeling Thermal Decomposition Kinetic Algorithms on CL-20 and HMX

International Journal of Chemical Reactor Engineering ◽

10.2202/1542-6580.2180 ◽

2010 ◽

Vol 8 (1) ◽

Author(s):

Chun-Ping Lin ◽

Jo-Ming Tseng ◽

Mei-Li You ◽

Yung-Chuan Chu ◽

Chi-Min Shu

Keyword(s):

Thermal Decomposition ◽

Kinetic Model ◽

Energy Parameter ◽

Operating Conditions ◽

Scanning Calorimetry ◽

Kinetic Evaluation ◽

Efficient Procedure ◽

Selection Of ◽

Thermal Decomposition Kinetic ◽

Decomposition Properties

This study established a kinetic model of the thermal decomposition properties of hexanitrohexaazaisowurtzitane (CL-20) and cyclotetramethylene tetranitramine (HMX) using differential scanning calorimetry (DSC) and kinetic evaluation simulations. The goal was to analyze the thermokinetic parameters of CL-20 and HMX by DSC and then to compare thermal decomposition energy parameter simulations under various conditions using a kinetic model. The experimental results that were obtained depend strongly on the reliability of the applied kinetic model, which is essentially defined by the suitable selection of a mathematical model and the accuracy of the methods used in the kinetic evaluation. This study resulted in a quick and efficient procedure for obtaining information about the thermal decomposition characteristics and the reaction hazards of CL-20 and HMX. This procedure could be applied to develop inherently safer reaction designs under normal or extraordinary operating conditions.

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GAS-Phase Decomposition Kinetics of MOVPE Precursors in a Counterflow Jet Reactor

MRS Proceedings ◽

10.1557/proc-282-157 ◽

1992 ◽

Vol 282 ◽

Cited By ~ 1

Author(s):

S. A. Safvi ◽

T. J. Mountziaris

Keyword(s):

Activation Energy ◽

Thermal Decomposition ◽

Gas Phase ◽

Experimental System ◽

Operating Conditions ◽

Tertiary Butyl ◽

Carrier Gas ◽

Hydride Elimination ◽

Counterflow Jet Reactor ◽

Stagnation Plane

ABSTRACTA new reactor for studying the purely homogeneous thermal decomposition of organometallic precursors used in the Metalorganic Vapor Phase Epitaxy (MOVPE) of semiconductors is presented. The idea is based on the use of a counterflow jet configuration with one jet being heated and the other unheated. The heated jet contains pure carrier gas (typically hydrogen or nitrogen), while the unheated jet contains vapors of an organometallic species diluted in the same carrier gas. Under appropriate operating conditions, decomposition of the organometallic species takes place near the stagnation plane where the hot jet collides with the cool jet. Since the reactions occur in the gas phase and away from hot walls, purely homogeneous kinetics can be obtained. Such a counterflow jet reactor was designed for studying the thermal decomposition of tertiary-butyl-arsine (TBA), t-C4H9AsH2, a very promising precursor for MOVPE of GaAs films. Two-dimensional finite element simulations of transport phenomena and kinetics have been used to identify optimal operating conditions. An experimental system was constructed and capillary-sampled mass spectroscopy at the stagnation plane was used to study the thermal decomposition of TBA in nitrogen at a total pressure of 252 Torr. Gas-chromatography of the effluent gas stream was employed for positive identification of the hydrocarbon byproducts. The results indicate the existence of two major decomposition routes: (1) A low activation energy pathway producing isobutane AsH, and (2) a higher activation energy, β-hydride elimination pathway producing isobutene and arsine.

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Thermal Decomposition of Aircraft Fuel

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.3239960 ◽

1986 ◽

Vol 108 (4) ◽

pp. 648-653 ◽

Cited By ~ 25

Author(s):

P. J. Marteney ◽

L. J. Spadaccini

Keyword(s):

Thermal Decomposition ◽

Small Diameter ◽

Aircraft Engine ◽

Operating Conditions ◽

Test Duration ◽

Heat Transfer Characteristics ◽

Test Program ◽

Aircraft Fuel ◽

The Relationship ◽

Fuel Deposition

A test program has been conducted to determine the thermal stability and heat transfer characteristics of JP-5 and several other kerosene-type fuels which vary in composition and tendency to form deposits. Tests were conducted in small-diameter, resistively heated tubes at typical aircraft engine operating conditions. A detailed mapping of the thermal decomposition characteristics of JP-5 was performed to evaluate the importance of key environmental factors—such as temperature, pressure, flowrate, and test duration—and to establish a data base for estimating the relative performance of new fuels. Tests were conducted over the temperature range 425 to 870 K for durations up to 32 hr. Fuel deposition rates varied among fuels, and the relationship between the “breakpoint temperature” (determined according to ASTM D3241) and the rate of fuel deposition was investigated.

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Experimental and Theoretical Studies of Burning Drops of Hydrocarbon Mixtures

Proceedings of the Institution of Mechanical Engineers Conference Proceedings ◽

10.1243/pime_conf_1969_184_324_02 ◽

1969 ◽

Vol 184 (10) ◽

pp. 95-108 ◽

Cited By ~ 2

Author(s):

C. S. Chen ◽

M. M. El-Wakil

Keyword(s):

Thermal Decomposition ◽

Equations Of State ◽

Species Conservation ◽

Chemical Species ◽

Operating Conditions ◽

Fuel Oil ◽

Symmetric Model ◽

Dimensionless Time ◽

Hydrocarbon Mixtures ◽

Wide Range

This paper presents an experimental and theoretical study of the self-ignition and burning behaviour of drops of hydrocarbon mixtures. In the experimental work, the mass histories, as well as temperature, shape, and flame histories, of drops of heavy hydrocarbon mixtures, suspended on fine thermocouple beads and subjected to heated air streams, were obtained. Due to thermal decomposition and irregular burning, the masses could not be determined from temperature and size and were measured by a liquid-nitrogen quenching technique. Temperature, flame, and shape histories were obtained in the usual manner by thermocouple and photographic means. Drops of grade 6 fuel oil and grade 6 fuel oil minus its asphaltene constituent, of 1·2 and 1·7 mg initial mass, subjected to 1450 and 1600°F air-stream temperatures, were studied. The drop histories can be divided into four phases: (1) pre-ignition, (2) self-ignition and combustion, (3) thermal decomposition, and (4) carbon residue, or cenosphere, burning. The asphaltenes contributed a great deal to burning irregularities but not to burning rates or temperatures. The latter were higher the higher the air temperature, but were affected less by changes in air velocity. In the theoretical work, a generalized treatment predicting the histories of drops undergoing unsteady vaporization, burning, thermal decomposition, or combinations of these was formulated. Based on a spherically symmetric model, governing equations of state, continuity, chemical species conservation, and energy conservation were solved with the aid of simplifying assumptions. A computer program was developed covering a wide range of operating conditions. The theoretical model showed reasonable agreement with the experimental results. A universal plot estimating drop histories of heavy residual fuels was prepared. The distribution of the total heat input into sensible heat, latent heat of vaporization, and endothermic heat of decomposition was also plotted versus dimensionless time.

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Thermal Decomposition of Nitrated Tri-n-Butyl Phosphate in a Flow Reactor

ISRN Chemical Engineering ◽

10.5402/2012/193862 ◽

2012 ◽

Vol 2012 ◽

pp. 1-9 ◽

Cited By ~ 6

Author(s):

Lalit K. Patil ◽

Vilas G. Gaikar ◽

Shekhar Kumar ◽

U. Kamachi Mudali ◽

R. Natarajan

Keyword(s):

Thermal Decomposition ◽

Atmospheric Pressure ◽

Flow Reactor ◽

Degradation Products ◽

Reaction Pathway ◽

Operating Conditions ◽

Purex Process ◽

Power Law Model ◽

Reaction Products ◽

Instrumental Methods

Tri-n-butyl phosphate (TBP) is a universal nuclear extractant, commercially used in the PUREX process for the last 60 years. However, it is prone to nitration and thermal degradation, and as a consequence a red-oil event may be initiated under several operating conditions resulting in severe pressurization of vessel/cell if venting is inadequate. In this work, an attempt was made to understand the reaction pathway of thermal decomposition of nitrated TBP in a flow reactor at atmospheric pressure. Many reaction products were identified and quantified by instrumental methods like HPLC-RI and GC-TCD. The experimental data was analysed with a power law model and the apparent rate constants were estimated. The activation energy for thermal decomposition of nitrated TBP, assuming an Arrhenius type of temperature dependency, was estimated to be 47.39 ± 0.25 kJ·mol−1. The effect of both varying temperature and concentration of nitric acid on conversion of TBP into degradation products and products distribution was experimentally studied. Based on the experimental observations, a reaction mechanism framework for thermal decomposition of nitrated TBP is proposed.

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Chemical compounds released by combustion of polymer composites flat belts

Scientific Reports ◽

10.1038/s41598-021-87634-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Piotr Krawiec ◽

Łukasz Warguła ◽

Dorota Czarnecka-Komorowska ◽

Paweł Janik ◽

Anna Dziechciarz ◽

...

Keyword(s):

Thermal Decomposition ◽

Hydrogen Bromide ◽

Chemical Compounds ◽

Operating Conditions ◽

Polymer Materials ◽

Gaseous Products ◽

Two Samples ◽

Conveyor Belts ◽

Heavy Loads ◽

Concentration Limits

AbstractMachines and devices for the production, transport and segregation of products are placed in production and storage rooms. Flat conveyor and drive belts are very often used for their construction. Due to heavy loads and difficult operating conditions, these belts can catch fire and, as a result, become the main source of air contaminants harmful to human health and life. This article examines the emission level of toxic chemical compounds most often produced during the thermal decomposition and combustion of flat drive and conveyor belts. Six types of flat belts, which were made of various polymer materials, i.e., polyamide, rubber, and polyurethane, and were pyrolyzed in a tube furnace at 950 °C, were tested for emission. Using an Fourier transform infrared spectroscopy gas analyser, five gaseous products of combustion were identified, i.e., carbon mono oxide, carbon dioxide, hydrogen cyanide, hydrogen bromide and sulfur dioxide (SO2). Chemical analysis showed that SO2 compounds and hydrogen bromide were present in only two samples. The test results indicate that gas emission concentration limits for all the tested belts were significantly exceeded. A comparative analysis of the concentration limits of V-belts described in the authors' earlier works shows that flat belts demonstrate lower emission levels of harmful compounds than V-belts. In addition, research has shown that compared to traditional rubber-based belts, belts made of modern materials exhibit no emission of hydrogen chloride compounds during thermal decomposition and combustion.

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Cathodoluminescence of Catalyst Crystallites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100055667 ◽

1982 ◽

Vol 40 ◽

pp. 664-665

Author(s):

E.D. Boyes ◽

P.L. Gai ◽

D.B. Darby ◽

C. Warwick

Keyword(s):

Defect Density ◽

Chemical Properties ◽

Operating Conditions ◽

Semiconductor Materials ◽

Environmental Cell ◽

High Resolution Structure ◽

Commercially Important ◽

Crystallographic Defects ◽

Resolution Structure

The extended crystallographic defects introduced into some oxide catalysts under operating conditions may be a consequence and accommodation of the changes produced by the catalytic activity, rather than always being the origin of the reactivity. Operation without such defects has been established for the commercially important tellurium molybdate system. in addition it is clear that the point defect density and the electronic structure can both have a significant influence on the chemical properties and hence on the effectiveness (activity and selectivity) of the material as a catalyst. SEM/probe techniques more commonly applied to semiconductor materials, have been investigated to supplement the information obtained from in-situ environmental cell HVEM, ultra-high resolution structure imaging and more conventional AEM and EPMA chemical microanalysis.

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100096230 ◽

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

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