Experimental Measurements and Modeling Prediction of Flammability Limits of Binary Hydrocarbon Mixtures PDF Download
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Author: Fuman Zhao Publisher: ISBN: Category : Languages : en Pages :
Book Description
Flammability limit is a significant safety issue for industrial processes. A certain amount of flammability limit data for pure hydrocarbons are available in the literature, but for industrial applications, there are conditions including different combinations of fuels at standard and non-standard conditions, in which the flammability limit data are scarce and sometimes unavailable. This research is two-fold: (i) Performing experimental measurements to estimate the lower flammability limits and upper flammability limits of binary hydrocarbon mixtures, conducting experimental data numerical analysis to quantitatively characterize the flammability limits of these mixtures with parameters, such as component compositions, flammability properties of pure hydrocarbons, and thermo-kinetic values; (ii) Estimating flammability limits of binary hydrocarbon mixtures through CFT-V modeling prediction (calculated flame temperature at constant volume), which is based on a comprehensive consideration of energy conservation. For the experimental part, thermal detection was used in this experiment. The experimental results indicate that the experimental results fit Le Chatelier's Law within experimental uncertainty at the lower flammability limit condition. At the upper flammability limit condition, Le Chatelier's Law roughly fits the saturated hydrocarbon mixture data, while with mixtures that contain one or more unsaturated components, a modification of Le Chatelier's is preferred to fit the experimental data. The easy and efficient way to modify Le Chatelier's Law is to power the molar percentage concentrations of hydrocarbon components. For modeling prediction part, the CFT-V modeling is an extended modification of CAFT modeling at constant volume and is significantly related to the reaction vessel configuration. This modeling prediction is consistent with experimental observation and Le Chatelier's Law at the concentrations of lower flammability limits. When the quenching effect is negligible, this model can be simplified by ignoring heat loss from the reaction vessel to the external surroundings. Specifically, when the total mole changes in chemical reactions can be neglected and the quenching effect is small, CFTV modeling can be simplified to CAFT modeling.
Author: Fuman Zhao Publisher: ISBN: Category : Languages : en Pages :
Book Description
Flammability limit is a significant safety issue for industrial processes. A certain amount of flammability limit data for pure hydrocarbons are available in the literature, but for industrial applications, there are conditions including different combinations of fuels at standard and non-standard conditions, in which the flammability limit data are scarce and sometimes unavailable. This research is two-fold: (i) Performing experimental measurements to estimate the lower flammability limits and upper flammability limits of binary hydrocarbon mixtures, conducting experimental data numerical analysis to quantitatively characterize the flammability limits of these mixtures with parameters, such as component compositions, flammability properties of pure hydrocarbons, and thermo-kinetic values; (ii) Estimating flammability limits of binary hydrocarbon mixtures through CFT-V modeling prediction (calculated flame temperature at constant volume), which is based on a comprehensive consideration of energy conservation. For the experimental part, thermal detection was used in this experiment. The experimental results indicate that the experimental results fit Le Chatelier's Law within experimental uncertainty at the lower flammability limit condition. At the upper flammability limit condition, Le Chatelier's Law roughly fits the saturated hydrocarbon mixture data, while with mixtures that contain one or more unsaturated components, a modification of Le Chatelier's is preferred to fit the experimental data. The easy and efficient way to modify Le Chatelier's Law is to power the molar percentage concentrations of hydrocarbon components. For modeling prediction part, the CFT-V modeling is an extended modification of CAFT modeling at constant volume and is significantly related to the reaction vessel configuration. This modeling prediction is consistent with experimental observation and Le Chatelier's Law at the concentrations of lower flammability limits. When the quenching effect is negligible, this model can be simplified by ignoring heat loss from the reaction vessel to the external surroundings. Specifically, when the total mole changes in chemical reactions can be neglected and the quenching effect is small, CFTV modeling can be simplified to CAFT modeling.
Author: Thuy Minh Hai Le Publisher: ISBN: Category : Languages : en Pages :
Book Description
Knowledge of flammability limits is essential in the prevention of fire and explosion. There are two limits of flammability, upper flammability limit (UFL) and lower flammability limit (LFL), which define the flammable region of a combustible gas/vapor. This research focuses on the flammability limits of hydrogen and its binary mixtures with light hydrocarbons (methane, ethane, n-butane, and ethylene) at sub-atmospheric pressures. The flammability limits of hydrogen, light hydrocarbons, and binary mixtures of hydrogen and each hydrocarbon were determined experimentally at room temperature (20℗ðC) and initial pressures ranging from 1.0 atm to 0.1 atm. The experiments were conducted in a closed cylindrical stainless steel vessel with upward flame propagation. It was found that the flammable region of hydrogen initially widens when the pressure decreases from 1.0 atm to 0.3 atm, then narrows with the further decrease of pressure. In contrast, the flammable regions of the hydrocarbons narrow when the pressure decreases. For hydrogen and the hydrocarbons, pressure has a much greater impact on the UFLs than on the LFLs. For binary mixtures of hydrogen and the hydrocarbons, the flammable regions of all mixtures widen when the fraction of hydrogen in the mixture increases. When the pressure decreases, the flammable regions of all mixtures narrow. The applications of Le Chatelier̕ s rule and the Calculated Adiabatic Flame Temperature (CAFT) model to the flammability limits of the mixtures were verified. It was found that Le Chatelier̕ s rule could predict the flammability limits much better than the CAFT model. The adiabatic flame temperatures (AFTs), an important parameter in the risk assessment of fire and explosion, of hydrogen and the hydrocarbons were also calculated. The influence of sub-atmospheric pressures on the AFTs was investigated. A linear relationship between the AFT and the corresponding flammability limit is derived. Furthermore, the consequence of fire relating to hydrogen and the hydrocarbons is discussed based on the AFTs of the chemicals. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/150966
Author: Fuman Zhao Publisher: ISBN: Category : Languages : en Pages :
Book Description
Flammability limit is a most significant property of substances to ensure safety of chemical processes and fuel application. Although there are numerous flammability literature data available for pure substances, for fuel mixtures these are not always available. Especially, for fuel mixture storage, operation, and transportation, inert gas inerting and blanketing have been widely applied in chemical process industries while the related date are even more scarce. Lower and upper flammability limits of hydrocarbon mixtures in air with and without additional nitrogen were measured in this research. Typically, the fuel mixture lower flammability limit almost keeps constant at different contents of added nitrogen. The fuel mixture upper flammability limit approximately linearly varies with the added nitrogen except mixtures containing ethylene. The minimum added nitrogen concentration at which lower flammability limit and upper flammability limit merge together is the minimum inerting concentration for nitrogen, roughly falling into the range of 45 plus/minus 10 vol % for all the tested hydrocarbon mixtures. Numerical analysis of inert gas dilution effect on lower flammability limit and upper flammability limit was conducted by introducing the parameter of inert gas dilution coefficient. Fuel mixture flammability limit can be quantitatively characterized using inert gas dilution coefficient plus the original Le Chatelier's law or modified Le Chatelier's law. An extended application of calculated adiabatic flame temperature modeling was proposed to predict fuel mixture flammability limits at different inert gas loading. The modeling lower flammability limit results can represent experimental data well except the flammability nose zone close to minimum inerting concentration. Le Chatelier's law is a well-recognized mixing rule for fuel mixture flammability limit estimation. Its application, unfortunately, is limited to lower flammability limit for accurate purpose. Here, firstly a detailed derivation was conducted on lower flammability limit to shed a light on the inherent principle residing in this rule, and then its application was evaluated at non-ambient conditions, as well as fuel mixture diluted with inert gases and varied oxygen concentrations. Results showed that this law can be extended to all these conditions.
Author: Mary N. Sandia National Labs Bui-Pham (Combustion Research Facility [email protected]) Publisher: ISBN: Category : Chemical plants Languages : en Pages : 12
Book Description
This research, a joint project between Sandia National Laboratories/California and Dow Chemical Company/Midland, is intended to examine existing flame modeling capability developed at Sandia to model experimental data for rich flammability limits. System studied is methanol/carbon monoxide/diluent mixtures, where the diluent is either nitrogen or carbon dioxide at pressures of 1, 11, and 21 atm, respectively. Critical oxygen concentration needed to sustain a flame was measured in a spherical vessel with a central ignition source for several mixtures and pressures. Burning velocities of 1-D, planar, freely propagating premixed flames were calculated to determine minimum oxygen concentration required for these flames to propagate. This minimum O[sub 2] concentration was found to be consistently larger than that observed in experiments; however, effects of pressure and diluent composition agreed well with experimental data. Attempts were made to model the spherical vessel experiment directly, which resultd in qualitative agreement with experimental data and steady flame predictions. In addition, the rich flammability limit was calculate for pure methanol-air flames to be at an equivalence ratio of [approximately] 2.1, and extincton occurs at K[sub ex] =1670 sec[sup [minus]1] for the opposed-flow, strained, stoichiometric methanol-air case.
Author: Mary N. Bui-Pham Publisher: ISBN: Category : Chemical plants Languages : en Pages : 22
Book Description
This research, a joint project between Sandia National Laboratories/California and Dow Chemical Company/Midland, is intended to examine existing flame modeling capability developed at Sandia to model experimental data for rich flammability limits. System studied is methanol/carbon monoxide/diluent mixtures, where the diluent is either nitrogen or carbon dioxide at pressures of 1, 11, and 21 atm, respectively. Critical oxygen concentration needed to sustain a flame was measured in a spherical vessel with a central ignition source for several mixtures and pressures. Burning velocities of 1-D, planar, freely propagating premixed flames were calculated to determine minimum oxygen concentration required for these flames to propagate. This minimum O[sub 2] concentration was found to be consistently larger than that observed in experiments; however, effects of pressure and diluent composition agreed well with experimental data. Attempts were made to model the spherical vessel experiment directly, which resultd in qualitative agreement with experimental data and steady flame predictions. In addition, the rich flammability limit was calculate for pure methanol-air flames to be at an equivalence ratio of [approximately] 2.1, and extincton occurs at K[sub ex] =1670 sec[sup [minus]1] for the opposed-flow, strained, stoichiometric methanol-air case.
Author: Publisher: ISBN: Category : Languages : en Pages : 22
Book Description
This research, a joint project between Sandia National Laboratories/California and Dow Chemical Company/Midland, is intended to examine existing flame modeling capability developed at Sandia to model experimental data for rich flammability limits. System studied is methanol/carbon monoxide/diluent mixtures, where the diluent is either nitrogen or carbon dioxide at pressures of 1, 11, and 21 atm, respectively. Critical oxygen concentration needed to sustain a flame was measured in a spherical vessel with a central ignition source for several mixtures and pressures. Burning velocities of 1-D, planar, freely propagating premixed flames were calculated to determine minimum oxygen concentration required for these flames to propagate. This minimum O2 concentration was found to be consistently larger than that observed in experiments; however, effects of pressure and diluent composition agreed well with experimental data. Attempts were made to model the spherical vessel experiment directly, which resultd in qualitative agreement with experimental data and steady flame predictions. In addition, the rich flammability limit was calculate for pure methanol-air flames to be at an equivalence ratio of (approximately) 2.1, and extincton occurs at K{sub ex} =1670 sec−1 for the opposed-flow, strained, stoichiometric methanol-air case.
Author: John Durkee Publisher: William Andrew ISBN: 1455731617 Category : Science Languages : en Pages : 779
Book Description
High-precision cleaning is required across a wide range of sectors, including aerospace, defense, medical device manufacturing, pharmaceutical processing, semiconductor/electronics, etc. Cleaning parts and surfaces with solvents is simple, effective and low-cost. Although health and safety and environmental concerns come into play with the use of solvents, this book explores how safe and compliant solvent-based cleaning techniques can be implemented. A key to this is the selection of the right solvent. The author also examines a range of newer "green" solvent cleaning options. This book supplies scientific fundamentals and practical guidance supported by real-world examples. Durkee explains the three principal methods of solvent selection: matching of solubility parameters, reduction of potential for smog formation, and matching of physical properties. He also provides guidance on the safe use of aerosols, wipe-cleaning techniques, solvent stabilization, economics, and many other topics. A compendium of blend rules is included, covering the physical, chemical, and environmental properties of solvents. - Three methods explained in detail for substitution of suitable solvents for those unsuitable for any reason: toxic solvents don't have to be tolerated; this volume explains how to do better - Enables users to make informed judgments about their selection of cleaning solvents for specific applications, including solvent replacement decisions - Explains how to plan and implement solvent cleaning systems that are effective, economical and compliant with regulations
Author: Migvia del C. Vidal Vázquez Publisher: ISBN: Category : Languages : en Pages :
Book Description
Flammability is an important factor of safe practices for handling and storage of liquid mixtures and for the evaluation of the precise level of risk. Flash point is a major property used to determine the fire and explosion hazards of a liquid, and it is defined as the minimum temperature at which the vapor present over the liquid at equilibrium forms a flammable mixture when mixed with air. Experimental tests for the complete composition range of a mixture are time consuming, whereas a mixture flash point can be estimated using a computational method and available information. The information needed for mixture flash point predictions are flashpoints, vapor pressures, and activity coefficients as functions of temperature for each mixture component. Generally, sufficient experimental data are unavailable and other ways of determining the basic information are needed. A procedure to evaluate the flash point of binary mixtures is proposed, which provides techniques that can be used to estimate a parameter that is needed for binary mixture flash point evaluations. Minimum flash point behavior (MFPB) is exhibited when the flash point of the mixture is below the flash points of the individual components of the mixture. The identification of this behavior is critical, because a hazardous situation results from taking the lowest component flash point value as the mixture flash point. Flash point predictions were performed for 14 binary mixtures using various G[superscript]ex models for the activity coefficients. Quantum chemical calculations and UNIFAC, a theoretical model that does not require experimental binary interaction parameters, are employed in the mixture flash point predictions, which are validated with experimental data. MFPB is successfully predicted using the UNIFAC model when there are insufficient vapor liquid data. The identification of inherent safety principles that can be applied to the flammability of binary liquid mixtures is also studied. The effect on the flash point values of three binary mixtures in which octane is the solute is investigated to apply the inherent safety concept.
Author: Wun K. Wong Publisher: ISBN: 9780771428906 Category : Languages : en Pages : 120
Book Description
Results show that the flammability data determined with thermal criteria has an acceptable level of accuracy. Recommendations for improving apparatus are made, based upon observations made while operating the flammability apparatus.
Author: Publisher: ISBN: Category : Languages : en Pages : 17
Book Description
One requirement regarding the transportation of transuranic (TRU) radioactive waste containers currently limits the total concentration of potentially flammable volatile organic compounds (VOCs) and flammable gases in the headspace of the waste container. Typical VOCs observed in the drums include aromatic hydrocarbons, ketones, alcohols, cyclohexane, as well as chlorinated hydrocarbons (alkanes and alkenes). Flammable gases, such as hydrogen and methane, may be generated in the containers by radiation-induced decomposition (radiolysis) of water and hydrocarbon waste forms. An experimental program was initiated to identify an accurate means for predicting flammability for gas mixtures containing one or more of the following species: hydrogen, carbon tetrachloride, 1,2-dichloroethane, toluene, or 2-butanone. The lower flammability limits (LFL) of gas mixtures containing equimolar quantity for each species were determined in a 19-liter laboratory flammability chamber using a strong spark ignition source. The group factor contribution method was determined to be more accurate than the LeChatelier method for estimating the LFL for these gas mixtures.
Author: Fuman Zhao
Author: Fuman Zhao
Author: Thuy Minh Hai Le
Author: Fuman Zhao
Author: Mary N. Sandia National Labs Bui-Pham (Combustion Research Facility 
Author: Mary N. Bui-Pham
Author: 
Author: John Durkee
Author: Migvia del C. Vidal Vázquez
Author: Wun K. Wong
Author: