Optimum conversion

In converter passes downstream of the first pass, exit temperatures are limited by thermodynamic equiUbrium to around 500°C or less. To obtain optimum conversion, the heats of reaction from succeeding converter passes are removed by superheaters or air dilution. The temperature rise of the process gas is almost direcdy proportional to the SO2 converted in each pass, even though SO2 and O2 concentrations can vary widely. 

As with chemical etches, developing optimum conversion coatings requires assessment of the microstructure of the steel. Correlations have been found between the microstructure of the substrate material and the nature of the phosphate films formed. Aloru et al. demonstrated that the type of phosphate crystal formed varies with the orientation of the underlying steel crystal lattice [154]. Fig. 32 illustrates the different phosphate crystal morphologies that formed on two heat-treated surfaces. The fine flake structure formed on the tempered martensite surface promotes adhesion more effectively than the knobby protrusions formed on the cold-rolled steel. 

The reactor model is also able to describe the dependence of conversion on the specific interfacial area (Figure 5.32) which passes through a maximum owing to the antagonistic role of increasing interfacial area at the expense of reducing residence time [10]. For a liquid volume flow of 50 ml h , optimum conversion was achieved at a specific interfacial area of 12 000 m m and at a residence time of 0.093 s. 

In Figure 13.17, the only cost forcing the optimum conversion back from high values is that of the reactor. Hence, for such simple reaction systems, a high optimum conversion would be expected. This was the reason in Chapter 5 that an initial value of reactor conversion of 0.95 of the maximum conversion was chosen for simple reaction systems. 

Figure 13.22 Putting all the costs together allows the optimum conversion and recycle inert concentration to be determined. (Reproduced from Smith R and Linnhoff B, 1988, Trans IChemE, CHERD, 66 195 by permission of the Institution of Chemical Engineers.)...

Influence of THP/Ru ratio and solvent systems. Many empirical studies were carried out on variation of conversions with the THP Ru ratio, defined as R, which was varied from 0.5 to 6.0. Invariably, in the H20/buffer standard conditions (and other solvent systems - see below), conversions for any selected reaction time decreased when R > 3, but this was not usually the optimum ratio. For the ketone 10b, the maximum conversion was at R = 3, but for ketone 10c and the alkene substrates such as lb and 3a, R was closer to 1 for 6c, the aldehyde substrate, optimum conversion was at R 2. The unknown nature of the catalytic species present in solution makes any discussion of these data meaningless. 

The time for optimized conversion has been determined by GLC for all olefins. It is crucial for all reactions to be stopped at optimum conversion, because slow decomposition of the allylic product occurs during the reaction. To obtain optimum yields one should follow the reaction by GLC. Optimized conversion is defined as allylic acetate/allylic acetate plus remaining olefin. 

Mass spectrometer analyses of the fractions taken at regular intervals indicate the optimum conversions of aromatic hydrocarbons directly to aldehydes and alcohols by oxidation, as shown in Table III. Semiquanti-tative yields derived from low voltage mass spectral intensities and values found by gas chromatography were generally in good agreement—for example, oxidations of toluene and p-xylene, worked up after 2 hours, gave the results shown in Table IV. 

By adjusting catalyst concentration from the higher value of Hay and Blanchard to that used in this study, we can direct the oxidation of aromatic hydrocarbons to increase the yields of alcohols and aldehydes. The oxidation period for optimum conversion can readily be determined by low voltage mass spectrometry. 

The bioconversion of (4/ )-(-)-limonene to (4/ )-(-)-a-terpineol by immobilised fungal mycelia of Penicillium digitatum was described more recently [86]. The fungi were immobilised in Calcium alginate beads. These beads remained active for at least 14 days when they were stored at 4°C. a-Terpineol production by the fungus was 12.83 mg/g beads per day, producing a 45.81% bioconversion of substrate. The optimum conversion temperature was 28°C and the optimum pH was 4.5. The highest... 

FAME production of rapeseed oil by alkali-catalyzed transesterification reaction was investigated. To obtain optimum conversion yield, anhydrous methanol and rapeseed oil with a free fatty acid content of <0.5% were used. The optimum conditions for alkali-catalyzed transesterification using KOH were determined as follows an oil to methanol molar ratio of 1 8 to 1 10 KOH, 1.0% (w/w) on the basis of oil weight, as catalyst a reaction temperature of 60°C and reaction time of 30 min. At these conditions, the FAME conversion yield was approx above 98%. From the refined FAME product (biodiesel), the FAME purity was obtained above 99% through posttreatment such as washing and centrifugation. 

If we employ optimum conversion levels in all of the runs, we may calculate E. in advance of the experiment. Using the results... 

Monomer Concentration. When 2-methyl-5-vinylpyridine is used alone, the incorporation or conversion of the monomer to block polymer is low, of the order of 10% of monomer used. However, conversion of vinylpyridine is increased greatly by the presence of acrylonitrile (Table II). Table II also shows that a lower temperature favors conversion, with 50°C. being optimum. Conversion at 70°C. is lower than at 30°C., even when twice the peroxide is used. 

Description The process consists of a reactor section, continuous catalyst regeneration section (CCR) and product recovery section. Stacked radial flow reactors (1) facilitate catalyst transfer to and from the CCR catalyst regeneration section (2). A charge heater and interheaters (3) are used to achieve optimum conversion and selectivity for the endothermic reaction. 

Description The process consists of a reactor section, continuous catalyst regeneration (CCR) section and product-recovery section. Stacked radial-flow reactors (1) facilitate catalyst transfer to and from the CCR catalyst regeneration section (2). A charge heater and interheaters (3) achieve optimum conversion and selectivity for the endothermic reaction. Reactor effluent is separated into liquid and vapor products (4). The liquid product is sent to a stripper column (5) to remove light saturates from the C6 aromatic product. Vapor from the separator is compressed and sent to a gas recovery unit (6). The compressed vapor is then separated into a 95% pure hydrogen coproduct, a fuel-gas stream containing light byproducts and a recycled stream of unconverted LPG. 

In case of reversible immobilization, minimum amount of the enzyme can be added, whenever required, to obtain optimum conversion rates. This results in considerable economy in cases where costly enzymes are required. 

The pressure drop showed that the reaction was usually completed in less than two hours, but heating was continued for four hours to ensure optimum conversions. The autoclave was allowed to stand overnight, the gaseous product was discharged, the autoclave was opened and the liquid product (usually chiefly in the liner) was recovered. The organic product was washed with water, dried and distilled and/or inspected by gas chromatography. 

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