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Chemistry and Thermodynamics

The following are the most important reactions that can occur during gasification, which involve conversion of carbon, carbon monoxide, carbon dioxide, hydrogen, water (or steam), and methane (Robinson, 2006 Speight, 2007). [Pg.108]

Modeling of Processes and Reactors for Upgrading of Heavy Petrole [Pg.110]

The reactions of oxidation (Equation 4.1), methanation (Equation 4.4), water-gas shift (Equation 4.5), and Boudouard (Equation 4.6) describe the four pathways in which a carbonaceous or hydrocarbon fuel can be gasified. Most gasification processes rely on a balance between partial oxidation reaction (Equation 4.1) and water-gas shift reaction (Equation 4.5). [Pg.110]

Water-gas shift reaction and methanation are normally favored at high temperatures ( 600°C). The composition of the final product gas is dependent on the degree of equilibrium attained by various gas-phase reactions. [Pg.110]

The chemical reactions that occnr in flames transform an initial reactant mixtnre into final reaction prodncts. In the case of fnel-oxygen combns-tion, the final prodncts are principally water vapor and carbon dioxide, althongh nnmerons other prodncts snch as carbon monoxide may be formed, depending on the reactant composition and other factors. If the ratio of fnel-to-oxygen is stoichiometric, the final reaction prodncts, by definition, contain no excess fnel or oxygen. Theoretically, this means that partial oxidation prodncts snch as CO (itself a fnel) are not formed. In reality, partial oxidation prodncts snch as CO or OH are formed by high tem-peratnre reactions. For example, the molar stoichiometric reaction of methane is written  [Pg.52]

Comparison of Stoichiometric and Most Easily Ignitable Concentrations for Five Gases and Vapors in Air [Pg.53]

Gas/Vapor Stoichiometric Concentration (vol %) Most Easily Ignitable Concentration (vol %) [Pg.53]

From Eq. (4-la) the stoichiometric concentration of methane in oxygen is 1 part in 3 = 33.3 mole percent methane. From Eq. (4-lb) the approximate stoichiometric concentration of methane in air is 1 part in 3 -E (158/21) = 9.5 mole percent methane. Tims, a mixtnre of 15 mole percent methane in oxygen has a stoichiometric ratio (p = 15/33.3 = 0.45 (lean), while the same methane concentration in air has a stoichiometric ratio (p = 15/9.5 = 1.58 (rich). [Pg.53]

For paraffins the stoichiometric ratio decreases as the nnmber of carbon atoms increases. Using a more precise calcnlation (which inclndes other species snch as CO, OH, etc.) than that shown in Eq. (4-lb), methane s stoichiometric ratio in air is 9.48 mole percent, propane s is 4.01 mole percent, and hexane s is 2.16 mole percent. Hydrogen, which combines with oxygen to form only water, has a stoichiometric ratio of 29.6 mole percent in air. [Pg.53]


Computational results can be related to thermodynamics. The result of computations might be internal energies, free energies, and so on, depending on the computation done. Likewise, it is possible to compute various contributions to the entropy. One frustration is that computational software does not always make it obvious which energy is being listed due to the dilferences in terminology between computational chemistry and thermodynamics. Some of these differences will be noted at the appropriate point in this book. [Pg.10]

Analytical chemistry is more than a collection of techniques it is the application of chemistry to the analysis of samples. As you will see in later chapters, almost all analytical methods use chemical reactivity to accomplish one or more of the following—dissolve the sample, separate analytes and interferents, transform the analyte to a more useful form, or provide a signal. Equilibrium chemistry and thermodynamics provide us with a means for predicting which reactions are likely to be favorable. [Pg.175]

Internal and External Phases. When dyeing hydrated fibers, for example, hydrophUic fibers in aqueous dyebaths, two distinct solvent phases exist, the external and the internal. The external solvent phase consists of the mobile molecules that are in the external dyebath so far away from the fiber that they are not influenced by it. The internal phase comprises the water that is within the fiber infrastmcture in a bound or static state and is an integral part of the internal stmcture in terms of defining the physical chemistry and thermodynamics of the system. Thus dye molecules have different chemical potentials when in the internal solvent phase than when in the external phase. Further, the effects of hydrogen ions (H" ) or hydroxyl ions (OH ) have a different impact. In the external phase acids or bases are completely dissociated and give an external or dyebath pH. In the internal phase these ions can interact with the fiber polymer chain and cause ionization of functional groups. This results in the pH of the internal phase being different from the external phase and the theoretical concept of internal pH (6). [Pg.351]

Chemistry and Thermodynamics. The principal reactions which occur in the methanation process are ... [Pg.11]

Steam-Moderated Process. The basic idea behind this approach is to limit the extent of conversion of the methanation reaction, Reaction 1, by adding steam to the feed gases. This process simultaneously provides for (46) elimination of the CO shift, Reaction 2, to get a 3 1 H2 CO ratio from the make-up gas ratio of about 1.5 1 and avoidance of carbon laydown by operation under conditions in which carbon is not a thermodynamically stable phase (see Chemistry and Thermodynamics section above). [Pg.36]

Chemistry and thermodynamics of europium and some of its simpler inorganic compounds and aqueous species. J. A. Rand, Chem. Rev., 1985, 85, 555 (343). [Pg.68]

CVI is a special CVD process in which the gaseous reactants penetrate (or infiltrate) a porous structure which acts as a substrate and which can be an inorganic open foam or a fibrous mat or weave. The deposition occurs on the fiber (or the foam) and the structure isgradually densified to form a composite.The chemistry and thermodynamics of CVT are essentially the same as CVD but the kinetics is different, since the reactants have to diffuse inward through the porous structure and the by-products have to diffuse out.f l Thus, maximum penetration and degree of densification are attained in the kinetically limited low-temperature regime. [Pg.129]

A lot of information regarding identification, structural characterization, quantitation, gas phase ion chemistry and thermodynamics can be obtained by MS. [Pg.40]

Analyses of the defect chemistry and thermodynamics of non-stoichiometric phases that are predominately ionic in nature (i.e. halides and oxides) are most often made using quasi-chemical reactions. The concentrations of the point defects are considered to be low, and defect-defect interactions as such are most often disregarded, although defect clusters often are incorporated. The resulting mass action equations give the relationship between the concentrations of point defects and partial pressure or chemical activity of the species involved in the defect reactions. [Pg.296]

Several electrochemical techniques may yield the reduction or oxidation potentials displayed in figure 16.1 [332-334], In this chapter, we examine and illustrate the application of two of those techniques cyclic voltammetry and photomodulation voltammetry. Both (particularly the former) have provided significant contributions to the thermochemical database. But before we do that, let us recall some basic ideas that link electrochemistry with thermodynamics. More in-depth views of this relationship are presented in some general physical-chemistry and thermodynamics textbooks [180,316]. A detailed discussion of theory and applications of electrochemistry may be found in more specialized works [332-334],... [Pg.229]

Equation (4.36) provides a simple method for estimating an important heat transfer dimensionless group called the Prandtl number. Recall from general chemistry and thermodynamics that there are two types of molar heat capacities, C , and the constant pressure heat capacity, Cp. For an ideal gas, C = 3Cpl5. The Prandtl number is... [Pg.317]

The content of both quantum chemistry and thermodynamics as traditionally presented, although essential to the background of any chemistry major, lacks a strong connection to the content of courses previously taken. This is not to say that physical chemistry textbooks lack connections to a student s previous study of chemistry, but it is clear that the typical student has difficulty seeing those connections. [Pg.283]

Reactive absorption, distillation, and extraction have much in common. First of all, they involve at least one liquid phase, and therefore the properties of the liquid state become significant. Second, they occur in moving systems, thus the process hydrodynamics plays an important part. Third, these processes are based on the contact of at least two phases, and therefore the interfacial transport phenomena have to be considered. Further common features are multicomponent interactions of mixture components, a tricky interplay of mass transport and chemical reactions, and complex process chemistry and thermodynamics. [Pg.321]

Level 1 Chemistry and Thermodynamics. This level deals with the analysis of the fundamental knowledge needed for performing the conceptual process design. A detailed description of chemistry is essential for designing the chemical reactor, as well as for handling safety and environmental issues. Here, the constraints set by chemical equilibrium or by chemical kinetics are identified. The nonideal behavior of key mixtures is analyzed in view of separation, namely by distillation. [Pg.24]

Basic Chemistry and Thermodynamics. The key to the understanding and use of rechargeable metal hydrides is the simple reversible reaction of a solid metal Me with gaseous H2 to form a solid metal hydride MeHx ... [Pg.300]

This chapter starts with a simplified analysis of biological processes using the basic tools of physics, chemistry, and thermodynamics. It provides a brief description of mitochondria and energy transduction in the mitochondrion. The study of proper pathways and multi-inflection points in bioenergetics are summarized. We also summarize the concept of thermodynamic buffering caused by soluble enzymes and some important processes of bioenergetics using the linear nonequilibrium thermodynamics formulation. [Pg.541]

My first interaction with the science of thermodynamics was not a pleasant one. And I have reasons to presume that for most science students the experience is similar. Soon after, 1 started patting myself on my back since 1 felt that 1 could understand the subject better than my classmates, and with a little help from my teachers 1 should be able to master the subject. But 1 found my teachers also woefully lacking in clarity of concepts. Thereafter, my enthusiasm for Physical Chemistry and Thermodynamics remained subsided until 1 became a student of metallurgy. The practical applicability of thermodynamics in metallurgical processes, and the clarity of concepts taught to us by Prof. K.P. Abraham, rekindled my interest so much so that, at that time 1 decided to make it my career. My Ph.D work was related to thermodynamic properties and 1 undertook teaching Metallurgical Thermodynamics, first at the Banaras Hindu University, and thereafter at Jamshedpur Technical Institute. [Pg.6]

Tribble J. S., Arvidson R. S., Lane M., Ill, and Mackenzie F. T. (1995) Crystal chemistry, and thermodynamic and kinetic properties of calcite, dolomite, apatite, and biogenic silica applications to petrologic problems. Sedim. Geol. 95, 11-37. [Pg.3503]

Rard J. A. (1983) Critical Review of the Chemistry and Thermodynamics of Technetium and some of its Inorganic Compounds and Aqueous Species. Lawrence Livermore National Laboratory, University of California, 86pp. [Pg.4799]


See other pages where Chemistry and Thermodynamics is mentioned: [Pg.52]    [Pg.307]    [Pg.502]    [Pg.70]    [Pg.742]    [Pg.206]    [Pg.219]    [Pg.70]    [Pg.28]    [Pg.29]    [Pg.31]    [Pg.186]    [Pg.12]    [Pg.41]    [Pg.5]    [Pg.300]    [Pg.297]    [Pg.82]    [Pg.168]    [Pg.166]    [Pg.37]    [Pg.499]   


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