Sieves types

Direct interception refers to a sieve-type mechanism in which contaminants larger than the filter pore size are directly trapped by the filter. This sieve retention mechanism of particle arrest is the mechanism of choice and occurs owing to geometric or spatial restraint. This type of particle arrest is considered to be absolute, that is, it is independent of filtration conditions. 

The 2eohtes are prepared as essentially bindedess preformed particles. The kaolin is shaped in the desired form of the finished product and is converted in situ in the pellet by treatment with suitable alkaU hydroxide solutions. Preformed pellets of 2eohte A are prepared by this method. These pellets may be converted by ion exchange to other forms such as molecular sieve Type 5A (1). ZeoHtes of higher Si02/Al202 ratios, eg, 2eohte Y, can be obtained by the same method, when sodium metasiUcate is incorporated in the preshaped pellets, or when acid-leached metakaolin is used. 

CARBON DIOXIDE CAPACITY AT 25 C Molecular Sieve Type A Equilibrium 0818... 

HYDROGEN SULFIDE CAPACfTY AT 25 Molecular Sieve Type A... 

Tetrahydrofuran may be purified by refluxing over solid potassium hydroxide, followed by distillation from lithium alu-miniun hydride. Tetrahydrofuran may be replaced by ethylene glycol dimethyl ether (dimethoxyethane). The submitter has indicated that either solvent may be freed conveniently from water, alcohols, and moderate amounts of peroxides by passing the commercial solvent through a column (2 in. diameter X 2-3 ft. length) of Linde Air Products Molecular Sieves (type 13A iQ- n. pellets), at a rate of approximately 100 ml. per minute. 

The importance of the downcomer seal is to prevent vapor from the tray from bubbling into the downcomer (see Figure 8-63), whether the trays are bubble cap, valve or sieve types. If a seal weir is not included in the tray design, then operation problems to avoid flooding, weeping and unstable performance, including pressure drop, are increased, particularly during the start-up phase. 

Figure 10-173. Direct contact tray column for heat transfer. This could be a baffle tray, sieve type tray, bubble or other contact device, or open spray or random packed column. (Symbols only used by permission Smith, J. H. Hydrocarbon Processing, Jan. 1979, p. 147. Gulf Publishing Company. All rights reserved.)...

Dried by distillation under reduced pressure and storage for several days over Linde Molecular Sieves Type 4A. 

A mixture of 7 (0.200 g. 0.97 mmol) and molecular sieves type 3A, 1/16 inch pellets (1 g) in benzene (40 mL) was refluxed for 6 h. The molecular sieves were filtered of) and the filtrate was evaporated in vacuo to leave 6c yield 0.130g (75%) pale-yellow prisms mp 46-49 C (acetone/hexanes). 

EDULJEE, H. E. (1958) Brit. Chem. Eng. 53, 14. Design of sieve-type distillation plates. 

With appropriate membrane pore size and a narrow distribution, membrane selectivity for smaller gas molecules can be high but the overall permeability is generally low due to a high flow resistance in fine pores. Several studies are being conducted to develop molecular sieve-type membranes using different inorganic materials, for example, those based on carbon (Liu, 2007), silica (Pex and van Delft, 2005), and zeolites (Lin, 2007). 

Two major new classes of molecular sieve type materials were reported in the 1990s (i) microporous frameworks based on mixed octahedral-tetrahedral frameworks in contrast to the previously described tetrahedral frameworks and (ii) mesoporous molecular sieves with pore sizes ranging from about 2 nm to greater than 10 nm. 

This work prompted a flurry of activity in the mid- to late 1980s to find the type IM isotherm. A number of inventions can be found in which alumina, or silica gel are blended with zeolites type X or Y to mimic the shape of the isotherm that Collier defined. Mol Sieve type DDZ-70(g) is in fact one of only a few true type IM isotherms. This product and Engelhard s type ETS-10 both have the required isotherm shape for water and deliver the benefits expected, to wit excellent capacity for water, self-sharpening mass transfer zone and low energy investment required to regenerate. Mol Sieve type DDZ-70(g) is used commercially in rotors... 

Molecular sieves, type 4A, size 1/16 inch pellets... 

N,N-Dimethylformamide is distilled under reduced pressure and stored over molecular sieves, type 4A. 

Dimethyl sulfoxide was distilled from calcium hydride and stored over Linde Molecular Sieves Type 3A. 

Figure 15.11. Effect of temperature on molecular sieve type 5A, silica gel and activated alumina at water vapor pressure, 13.3 kPa (lOOmmHg). A, molecular sieve type 5A B, silica-type adsorbent C, alumina-type adsorbent. (Chi and Cummings, 1978).

In an additional experiment, it was verified that under the conditions employed here, the uptake of nitrogen by molecular sieve type 3A (KA) is negligible. 

To this point we have covered general tray design for any type of tray— valve, bubble cap, or sieve type. Beginning here, we will review the design and rating of valve-type trays, followed by bubble cap and sieve tray design and rating. 

The jet flood equation is also based on the work of Souders and Brown [12]. This equation computes the ratio of the square power of the vapor load (noted in this chapter as Vload) to a constant, 8.75, to derive the tray flood. It has been used for over three decades by tray vendors (Koch and F.W. Glitsch [3]) to design and rate sieve-type trays. In many cases, especially for sieve-type tray design, jet flood governs tray flood and thus is the primary sieve tray design and rating equation. In contrast, Eqs. (3.88) through (3.90) are the principal equations for flood determination for both valve- and bubble cap-type trays. 

An extractor column is generally a tall, vertical packed tower that has two or more bed sections. Each packed bed section is typically limited to no more than 8 ft tall, making the overall tower height about 40 to 80 ft. Tower diameter depends fully upon liquid rates, but is usually in the range of 2 to 6 ft. Liquid-liquid extractors may also have tray-type column internals, usually composed of sieve-type trays without downcomers. These tray-type columns are similar to duoflow-type vapor-liquid separation, but here serve as contact surface area for two separate liquid phases. The packed-type internals are more common by far and are the type of extractor medium considered the standard. Any deviation from packed-type columns is compared to packing. 

Traps (specifically foreline traps) can also improve the vacuum in a vacuum system either by becoming a separate vacuum station (such as the cryogenic capabilities of a cold trap) or by limiting the backflow of oils from a pump (either a cold trap or a molecular sieve type trap). 

Abstract. Activated carbon Norit R 08 Extra, and molecular sieve type 4A, were investigated using dynamic (tert-butylbenzene (TBB), cyclohexane (CHX) and water vapour) adsorption methods. The TBB, CHX and water breakthrough plots for fixed activated carbon - molecular sieve beds were analyzed. It was found that the type of bed composition with mechanically mixed activated carbon with molecular sieve, or separated activated carbon and molecular sieve layers, affects the dynamic adsorption characteristics. 

Two different adsorbents, activated carbon Norit R 0.8 Extra (Norit N.V., The Netherlands) and molecular sieve (type 4A, Merck), were used to study tert-butylbenzene, cyclohexane, and water vapour breakthrough dynamics. Structural parameters of the carbon adsorbent were calculated from benzene vapour adsorption-desorption isotherms measured gravimetrically at 293 K using a McBain-Bakr quartz microbalance, and nitrogen adsorption-desorption isotherms recorded at 77.4 K using a Micromeritics ASAP 2405N analyzer described in detail elsewhere.22,24 Activated carbon Norit has a cylindrical... 

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