The Second Phase

Note that 0i (t) occurs only in the same terms as s(t) and ei (f) so that, to first order, we can put 

In this phase, the two parameters of interest are the total collision time and the coefficient of restitution. We will denote the former quantity by T. It is the time at which the contact region reduces to zero. Using (5.3.38) and remembering that a(0] (t)) = a t), we see that, to first order, 

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For methyl alcohol, two volumes of synthetic n-hexane, b.p. 68-6-69 0° (uncorr.), and one volume of the alcohol to be tested are mixed and the homogeneous mixture is cooled in ice until the appearance of a cloudiness. A thermometer is placed in the solution, which is allowed to warm gradually to the temperature at which the second phase disappears. The... 

Extraction Between Two Phases When the sample is initially present in one of the phases, the separation is known as an extraction. In a simple extraction the sample is extracted one or more times with portions of the second phase. Simple extractions are particularly useful for separations in which only one component has a favorable distribution ratio. Several important separation techniques are based on simple extractions, including liquid-liquid, liquid-solid, solid-liquid, and gas-solid extractions. 

The Record of Invention. The second phase of developing a record of the invention is to condense the record into a summary form which serves several purposes. Specifically, the record of invention estabUshes a date of invention through attached copies of notebook records, spectra, and the like which all prove that the invention has in fact been conceived and reduced to practice in some form having practical utihty. 

In the second phase, performed at a maximum temperature of about 370°C, the sulfur and a portion of the coke are removed by combustion. The rate and exothermicity are controlled by limiting the flow of combustion gas through the catalyst. Spent base metal catalysts may have sulfur levels of from 6 to 12 wt % in the form of metal sulfides. A high degree of sulfur removal must be achieved in these first two regeneration steps to avoid the formation of sulfate on the support during the final combustion step. Such a formation causes a loss of catalyst activity. 

Polyphase Alloys. The two-phase alloys have a rather wide range of properties resulting from variations within the stmcture. If the second phase is distributed in critical depression, the hardness and strength are at a maximum and the ductility is at a moderate level. Tensile strength may be 415—825 MPa (60,000—120,000 psi) yield strength, 170—585 MPa (25,000—85,000 psi) and elongation, 10—40%. 

Another process for the production of dodecanedioic acid is by oxidation of cyclododecene using a two-phase system in which mthenium tetroxide serves as the oxidizing agent in the organic phase, and is regenerated in the second phase, an aqueous phase containing cerium(IV) ions (75). 

If the equilibrium relation y° = F Xi) is sufficiently simple, e.g., if a plot of yfversus Xi is a straight hne, not necessarily through the origin, the rate of transfer is proportional to the difference between the bulk concentration in one phase and the concentration (in that same phase) which would be in equilibrium with the bulk concentration in the second phase. One such difference isy — y°, and another is x° — x. In this case, there is no need to solve for the interfacial compositions, as may be seen from the following derivation. 

The feed to a liquid-liquid extraction process is the solution that contains the components to be separated. The major liquid component in the feed can be referred to as the feed solvent. Minor components in solution are often referred to as solutes. The extraction solvent, or just plain solvent, is the immiscible liquid added to a process for the purpose of extracting a solute or solutes from the feed. The extraction-solvent phase leaving a liquid-liquid contactor is called the extract. The raffinate is the liquid phase left from the feed after being contacted by the second phase. A wash solvent is a hquid added to a liquid-liquid fractionation process to wash or enrich the purity of a solute in the extract phase. 

The triggering mechanism for the corrosion process was localized depassivation of the weld-metal surface. Depassivation (loss of the thin film of chromium oxides that protect stainless steels) can be caused by deposits or by microbial masses that cover the surface (see Chap. 4, Underdeposit Corrosion and Chap. 6, Biologically Influenced Corrosion ). Once depassivation occurred, the critical features in this case were the continuity, size, and orientation of the noble phase. The massive, uninterrupted network of the second phase (Figs. 15.2 and 15.21), coupled... 

Fig. 2.7. Many metals are made up of /wo phases. This figure shows some of the shapes that they con hove when boundary energies dominate. To keep things simple we hove sectioned the tetrokoidecohedral grains in the way that we did in Fig. 2.6(b). Note that Greek letters ore often used to indicate phases. We hove called the major phase a and the second phase (. But y is the symbol for the energy (or tension) of groin boundaries (y J and interphose interfaces (y ).

The second phase can, of course, form complete grains (Fig. 2.7d). But only if 7, and 7gb are similar will the phases have tetrakaidecahedral shapes where they come together. In general, 7, and 7gb may be quite different and the grains then have more complicated shapes. 

One of the most comprehensive economic studies was done in two phases. The first phase addressed whether the location of the treating facilities should be offshore or onshore. The second phase evaluated the process design options. The outcome of the first phase recommended onshore natural gas treating facilities the second phase recommended implementation of the turboexpander process design. The process options evaluated for this project are listed below ... 

The second phase, becoming effective January 1, 2000, will require approximately 2000 utilities to reduce their emissions to a level equivalent to the product of an emissions rate of (1.2 lbs of S02/mm Btu) X (the average mm Btu of their 1985-1987 fuel use). In both phases, affected sources will be required to install systems that continuously monitor emissions in order to track progress and assure compliance. 

The second phase in resole formation is reaction of the activated phenol with the aldehyde to form the phenol alcohol derivative. When the aldehyde is formaldehyde, the derivative is a hydroxymethyl phenol and the process is known as methylolation. Scheme 2 illustrates this reaction. Since resoles are usually made with excess aldehyde, more than one substitution may be made on the ring. When the reactants are phenol and formaldehyde, up to three methylol groups may be substituted. This reaction has been extensively studied and the rates of... 

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