摘要:

Experimental measurements of scalar quantities in laminar counter-flow diffusion flames of mixtures of trichloroethylene (TCE) with methane have been compared with an equilibrium calculation. The data are correlated in terms of a mixture fraction. Data for stable major and minor species were obtained by using gas sampling with gas chromatography (GC) and a GC/mass spectrometer in flames with high (248 s−1) and low (175 s−1) strain rates. Calculations indicated that TCE mass fractions at equilibrium were very small, even at a relatively low temperature (600 K). However, the GC measurements showed that TCE persisted well into the flame. Strain rate was found to have a small but measurable effect on the correlation of species mass fractions and temperature with mixture fraction. The comparison of equilibrium predictions with measurements in mixture fraction space suggests that finite rate chemistry and chemical kinetics should be considered in the modeling of chlorinated hydrocarbon turbulent diffusion flames. This conclusion also applies to products of incomplete combustion such as the chlorinated polyaromatic hydrocarbons. A laminar flamelet model for turbulent diffusion flames of chlorinated hydrocarbons should yield significantly better results than an equilibrium model of the thermochemistry.

ISSN:0010-2202    

DOI:10.1080/00102209408951882

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A turbulent reacting flow model has been developed, based upon a stochastic modeling approach that is applicable over a wide range of Reynolds and Schmidt numbers. All relevant length scales are resolved in one dimension which allows for direct implementation of detailed chemical kinetic calculations and molecular transport. Experiments were performed in a turbulent plug flow reactor for validation and application of the model to investigate the combined effects of turbulent mixing and chlorine chemistry on the formation of products of incomplete combustion. Methyl chloride was injected into the plug flow reactor whose baseline flow was the hot-product stream of a Toroidal Jet-Stirred Combustor. The micromixing and chemical reaction of the injected material with the baseline flow was monitored as a function of distance from the point of injection. Measurements of pulsed laser Rayleigh scattering were used to determine the extent of mixing while species concentrations were measured via extractive sampling and GC/MS. Preliminary comparisons of model calculations and data are provided which indicate the usefulness of the current modeling approach and provide insight into the relative contributions of mixing and chemical kinetics on the formation of products of incomplete combustion.

ISSN:0010-2202    

DOI:10.1080/00102209408951883

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A collaborative research program has been initiated to study the emissions of a wide variety of chemical species from stationary combustion systems. These product species have been included in Clean Air act legislation and their emissions must be rigidly controlled, but there is a need for a much better understanding of the physical and chemical mechanisms that produce and consume them. We are using numerical modeling techniques to study the chemical reactions and fluid mechanical factors that occur in industrial burners. We are examining systems including perfectly-stirred and plug-flow reactors, and diffusion flames in these modeling studies to establish the major factors leading to emissions of these chemicals.

ISSN:0010-2202    

DOI:10.1080/00102209408951884

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Manufacture of chlorinated hydrocarbon (RCI) based products includes treating the associated waste streams. On the basis of “Best-Available-Technology, ”waste disposal is generally accomplished using vent incinerators (thermal oxidizers). Vent incineration may lead to the formation of undesirable Products of Incomplete Combustion (PIC's). The recent Boiler & Industrial Furnace (BIF) regulations have required that companies certify the ability of their Thermal Oxidizers (TOXs) to meet these new emissions* regulations.

ISSN:0010-2202    

DOI:10.1080/00102209408951885

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

To study the suitability of numerical simulations for predicting incinerator-related flows, an experimental and computational study of an obstacle flow with some of the features of incinerator flows is performed. Results of LDV measurements from a water channel experiment on the flow over a triangular obstacle and from a concurrent FEM simulation using the standard κ-ϵ turbulence model are compared. The reattachment length predicted by the computations agrees to within 3% with the experimentally determined value. The mean velocity profiles and the shapes of the turbulent kinetic energy profiles show good agreement. A more realistic model of the flow in an incinerator is studied briefly and provides information on the appropriate choice of outflow boundary conditions for computing flows in truncated domains. The standard κ-ϵ model was found to be useful in making predictions of separated flows with similarities to those found in incinerators. Special exit boundary conditions which allow for a pressure variation independent of the viscous normal stresses were found to predict realistic outflow velocity profiles.

ISSN:0010-2202    

DOI:10.1080/00102209408951886

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Hydrocarbon evolution from a montmorillonite clay-soil was studied at three scales and at temperatures ranging from 300 to 650°C in order to develop a thermal treatment assessment procedure for contaminated soils in rotary kilns. The two components of the assessment procedure included experimental evaluation of the soil at bench- or pilot-scale in conjunction with data fitting using an appropriate mathematical desorption model. The results of the experiments have been embodied in the model which can be used for scaling and correlative purposes. Performing experiments at three scales permitted a clear delineation of intraparticle and interparticle effects and it also allowed the testing of the model's ability to correctly scale results. In addition to reactor size, the key parameters examined included hydrocarbon volatility, temperature, moisture levels, and soil particle size.

ISSN:0010-2202    

DOI:10.1080/00102209408951887

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The effect of the presence of non-catalytic particles on combustor performance was studied experimentally. A spouted bed was used as the combustor with sand as the heterogeneous medium and propane as the fuel. A surface area (particle size) dependent heterogeneous effect of fuel conversion, hydrocarbon products due to incomplete combustion formation and carbon monoxide generation was observed. A change in bed medium to glass beads resulted in more efficient combustion. Fine particles generated in the bed due to fragmentation appear to make a significant contribution to the emissions from such a heterogeneous combustor.

ISSN:0010-2202    

DOI:10.1080/00102209408951888

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Incineration is an important disposal method for the large volumes of sludge produced by industrial and municipal waste water treatment. This paper describes analytical methods developed for examining industrial sludge incineration processes and the dependence of potential products of incomplete combustion (PICs) on the sludge composition. A surrogate sludge was developed from peat, calcium and iron salts, and a waste water-treatment polymer suspension to simulate incineration characteristics of the real sludge while allowing for controlled variation of its composition. Experiments were conducted under both oxidative and pyrolysis conditions, in reactor systems ranging from microscale up to bench scale with on-line analytical instrumentation. The organic products emitted from the surrogate were quite similar to those of the sludge, with the exception of products from certain synthetic polymers. Significant quantities of aromatic hydrocarbons were emitted from the combustion of the cellulosic and lignin fractions of the material even without the presence of those specific compounds in the original waste. The presence of the metal salts and the additional water they retained significantly affected the peak hydrocarbon concentration by delaying the onset of emissions and lengthening their duration. The amount of polystyrene and polymethylmethacrylate in the real sludge made their decomposition products important potential PICs, which would need further combustion.

ISSN:0010-2202    

DOI:10.1080/00102209408951889

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This experimental study was mainly aimed to evaluate the influence of the coal type on the production of Polycyclic Aromatic Hydrocarbons (PAHs) and other trace organics from pulverized coal combustion.

ISSN:0010-2202    

DOI:10.1080/00102209408951890

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Air Pollution Control (APC) residues from Municipal Waste Combustion (MWC) typically contain high concentrations of potentially toxic metals. APC residues, consisting of fly ash and lime spray drier scrubber residue, were sieve separated into six size fractions. Residue characterization included physical and morphological classification and chemical speciation. Elemental distributions as a function of particle size indicated parabolic distributions for matrix species and sigmoidal distributions for volatile species. Unreacted lime in the scrubber residue preferentially was present in the smallest fractions which greatly altered the elemental distribution profiles. Mathematical correction for this highly water soluble portion of the residue normalized the data which showed extreme similarity between facilities. Parabolic profiles became nearly linear with negative slopes and sigmoidal trends were transformed into exponential curves. This included adjusted lead concentrations approaching 2 wt% and zinc concentrations up to 8 wt% in the smallest fractions.

ISSN:0010-2202    

DOI:10.1080/00102209408951891

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor