Performance data

Table 10.11 provides some general performance data on a visbreaking process applied on a typical VR. 

The applicability of mesoscale techniques to systems difficult to describe in any other manner makes it likely that these simulations will continue to be used. At the present time, there is very little performance data available for these simulations. Researchers are advised to carefully consider the fundamental assumptions of these techniques and validate the results as much as possible. 

Practically all cyclone performance data have been related to a present cyclone set of geometric ratios. One model for cyclone grade-efficiency curves has been tested against reported commercial cyclone efficiencies (159). A good fit was obtained. 

Fig. 16. Performance data obtained ia laboratory cells using Nafion NX-961, DSA anode, activated cathode, narrow gap, at 90°C. Energy consumption is...

Eor design of a large-scale commercial extractor, the pilot-scale extractor should be of the same type as that to be used on the large scale. Reflable scale-up for industrial-scale extractors still depends on correlations based on extensive performance data collected from both pilot-scale and large-scale extractors covering a wide range of Hquid systems. Only limited data for a few types of large commercial extractors are available in the Hterature. 

Motionless inline mixers obtain energy for mixing and dispersion from the pressure drops developed as the phases flow at high velocity through an array of baffles or packing in a tube. Performance data on the Kenics (132) and Sul2er (133) types of motionless mixer have been reported. 

The Oldshue-Rushton column (Eig. 15d) was developed (162) in the early 1950s and has been widely used in the chemical industry. It consists essentially of a number of compartments separated by horizontal stator-ring baffles, each fitted with vertical baffles and a turbine-type impeller mounted on a central shaft. Columns up to 2.74 m in diameter have been reported in service (162—167). Scale-up is reported to be reliably predictable (168) although only limited performance data are available (169). A detailed description and review of design criteria are available (170). 

A specially designed water induction system was used in the Provo-Orem bus to increase the water induction mass ratio when operating at or near full power setting. Engine performance data as a function of the equivalence ratio and water injection mass ratio are shown in Figure 7. 

By-products include propylene dibromide, bis-(bromopropyl) ether, propylene glycol, and propionic acid. Bromide losses are to the brominated organics and bromate formation. Current efficiency is a function of ceU design and losses to bromate. Energy consumption decreases with an increase in electrolyte concentration and a decrease in current density. Space—time yield increases with current density. See Table 5 for performance data (see... 

Vendor information (available materials, their composition, properties and applications available sizes, shapes and geometry availability, delivery schedule, cost and performance data)... 

Filtration is employed when the suspended soUds concentration is less than 100 mg/L and high effluent clarity is required. Finely dispersed suspended soUds require the addition of a coagulant prior to filtration. Filters most commonly used in wastewater treatment are a dual media (anthrafUt and sand) or a moving bed or continuous-backwash sand filter. Performance data for the tertiary filtration of municipal and industrial wastewater are shown in Table 10. 

With the exception of the ADI process, anaerobic processes usually operate at a temperature of 35°C. In order to maintain this temperature, the methane gas generated ia the process is used to heat the reactor. Anaerobic processes are shown ia Figure 18. Anaerobic treatment performance data are shown ia Table 14. 

The hterature consists of patents, books, journals, and trade Hterature. The examples in patents may be especially valuable. The primary Hterature provides much catalyst performance data, but there is a lack of quantitative results characterizing the performance of industrial catalysts under industrially reaHstic conditions. Characterizations of industrial catalysts are often restricted to physical characterizations and perhaps activity measurements with pure component feeds, but it is extremely rare to find data characterizing long-term catalyst performance with impure, multicomponent industrial feedstocks. Catalyst regeneration procedures are scarcely reported. Those who have proprietary technology are normally reluctant to make it known. Readers should be critical in assessing published work that claims a relevance to technology. 

One goal of catalyst designers is to constmct bench-scale reactors that allow determination of performance data truly indicative of performance in a full-scale commercial reactor. This has been accompHshed in a number of areas, but in general, larger pilot-scale reactors are preferred because they can be more fully instmmented and can provide better engineering data for ultimate scale-up. In reactor selection thought must be given to parameters such as space velocity, linear velocity, and the number of catalyst bodies per reactor diameter in order to properly model heat- and mass-transfer effects. 

This equation has two unknowns Xq and Xe), and an empirical relation between them is needed. Many have been tried, and one of the best is to assume that the excess of To over Te expressed as a ratio to Tp (zero for a perfectly stirred chamber) is a constant A [ (Tg — Tg)/ Tp]. Although A should vaiy with burner type, the effects of firing rate and percent excess air are small. In the absence of performance data on the land of furnace under study, assume A = 300/Tp, °R or 170/Tp, K. The left side of Eq. (5-178) then becomes D 1 —Xc + A), and with coefficients of Xc and Xc collected, the equation becomes... 

Collapse of vapor bubbles once they reach zones where the pressure exceeds the vapor pressure can cause objectionable noise and vibration and extensive erosion or pitting of the boundaiy materials. The critical cavitation number at inception of cavitation, denoted <7, is useful in correlating equipment performance data ... 

For quick pump selec tion, manufacturers often give the most essential performance details for a whole range of pump sizes. Figure 10-30 shows typical performance data for a range of process pumps based on suction and discharge pipes and impeller diameters. The performance data consists of pump flow rate and head. Once a pump... 

Another development features a nonmetallic belt [Pla.st. Des. Process., 13 (July 1968)]. When rapid heat transfer is the objective, a glass-fiber, Teflon-coated construction in a thickness as httle as 0.08 mm (0.003 in) is selected for use. No performance data are available, but presumably the thin belt permits rapid heat transfer while taking advantage of the nonsticking property of Teflon. Another development [Food Process. Mark., 69 (March 1969)] is extending the capa-bihty of belt solidification by providing use of subzero temperatures. 

Tests on plant-scale dryers are usually carried out to obtain design data for a specific material, to select a suitable diyer type, or to check present performance of an existing diyer with the objective of determining its capacity potential. In these tests overall performance data are obtained and the results used to make heat and material balances and to estimate overall drying rates or heat-transfer coefficients. 

Initial comparison of diyers. The diyers so selected should be evaluated approximately from available cost and performance data. From this evaluation, those diyers which appear to be uneconomical or unsuitable from the standpoint of performance should be eliminated from further consideration. 

Performance Data for Direct-Heat Tray Dryers A standard two-truck diyer is illustrated in Fig. 12-48. Adjustable baffles or a perforated distribution plate is normally employed to develop 0.3 to 1.3 cm of water-pressure drop at the wall through which air enters the truck enclosure. This will enhance the uniformity of air distribution, from top to bottom, among the trays. In three (or more) truck ovens, air-reheat coils may be placed between trucks if the evaporative load is high. Means for reversing air-flow direction may also be provided in multiple-truck units. 

Performance data on some typical tray and compartment diyers are tabulated in Table 12-10. These indicate that an overall rate of evaporation of 0.0025 to 0.025 kg water/(s m") of tray area may be expected from tray and tray-truck diyers. The thermal efficiency of this type of diyer will vary from 20 to 50 percent, depending on the diying temperature used and the humidity of the exhaust air. In diying to very low moisture contents under temperature restrictions, the thermal efficiency may be in the order of 10 percent. The major operating cost for a tray diyer is the labor involved in loading and unloading the trays. About two labor-hours are required to load and unload a standard two-truck tray diyer. In addition, about one-third to one-fifth of a... 

TABLE 12-10 Manufacturer s Performance Data for Tray and Tray-Truck Dryers ... 

Performance Data for Vacttum-Shelf Dryers The purchase price of a vacuum-shelf dryer depends upon the cabinet size and number of shelves per cabinet. For estimating purposes, typical prices (1985) and auxiliai y-emiipment requirements are given in Table 12-12. Installed cost of the equipment will be roughly 100 percent of the carbon steel purchase cost. 

TABLE 12-13 Performance Data of Vacuum-Shelf Dryers... 

Experimental performance data are given in Table 12-15 for numer-... 

TABLE 12-16 Performance Data for Continuous Through-Circulation Dryers ... 

PSYCHROMETRY, EVAPORATIVE COOLING, AND SOLIDS DRYING TABLE 12-18 Warm-Air Direct-Heat Cocurrent Rotary Dryers Typical Performance Data ... 

Some commercial performance data for cement and lime kilns are shown in Table 12-20. 

Table 12-23 outhnes typical performance data from three drying apphcations in steam-tube dryers. 

TABLE 12-23 Steam-Tube Dryer Performance Data... 

Performance and Cost Data for Batch Vacuum Rotary Dryers Typical performance data for vacuum rotaiy diyers are given in Table 12-26. Size and cost data for rotaiy agitator units are given in Table 12-27. Data for double-cone units are in Table 12-28. 

Performance and Cost Data for Turbo-Tray Dryers Performance data for three apphcations of closed-circuit diying are included in Table 12-29. Operating, labor, and maintenance costs compare favorably with those of direct-heat rotating eqmpment. 

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