Vacuum condensers

Type 77 units are the condenser and reboiler designs. One side is spiral flow and the other side is in cross flow. These SHEs provide veiy stable designs for vacuum condensing and reboiling seiwices. A SHE can be fitted with special mounting connec tions for refliix-type vent-condenser apphcations. The vertically mounted SHE directly attaches on the column or tank. 

Applications The common Heliflow apphcations are tank-vent condensers, sample coolers, pump-seal coolers, and steam-jet vacuum condensers. Instant water heaters, glycoLwater seivdces, and cryogenic vaporizers use the spiral tube s ability to reduce thermally induced stresses caused in these apphcations. 

Entering vacuum condensers to cut down pressure drop... 

Figure 1. Baffling and inlet bathtub are shown in this typical vacuum condenser design.

Another example of pressure control by variable heat transfer coefficient is a vacuum condenser. The vacuum system pulls the inerts out through a vent. The control valve between the condenser and vacuum system varies the amount of inerts leaving the condenser. If the pressure gets too high, the control valve opens to pull out more inerts and produce a smaller tube area blanketed by inerts. Since relatively stagnant inerts have poorer heat transfer than condensing vapors, additional inerts... 

A vacuum condenser has vacuum equipment (such as steam jets) pulling the noncondensibles out of the cold end of the unit. A system handling flammable substances has a control valve between the condenser and Jets (an air bleed is used to control nonflammable systems). The control method involves derating part of the tube surface by blajiketing it with noncondensibles that exhibit poor... 

The control valve allows the Jets to pull noncondensibles out of the condenser as needed for system pressure control. In addition to requiring extra surface area for control, the vacuum condenser also needs enough surface area for subcooling to ensure that the Jets do not pull valuable hydrocarbons or other materials out with the noncondensibles. To allow proper control and subcooling, some designers add approximately 50% to the calculated length. 

In direct contact heal exchange, there is no wall to separate hot and cold streams, and high rales of heal transfer are achieved. Applications include reactor off-gas quenching, vacuum condensers, desuperheating, and humidification. Water-cooling lowers are a particular example of a direct contact heal e.xchanger. In direct contact cooler-condensers, the condensed liquid is frequently used as the coolant. 

Plate and frame e.xchangers (plate heat exchangers)-used for heating and cooling in reactor off-gas quenching, vacuum condensers, desuperheating, and humidification. 

Pressure drop is only likely to be a major consideration in the design of vacuum condensers and where reflux is returned to a column by gravity flow from the condenser. 

Round-bottomed flasks should always be employed, or, in certain cases, filter flasks, but the latter should only be warmed cautiously. If, as so often happens in the case of sensitive substances, large amounts of solvent have to be removed by distillation in a vacuum, condensation is accelerated by the use of a fairly large condenser and, where necessary, by cooling the receiver with ice. 

V band spect Absorption bands that appear in the ultraviolet part of the spectrum due to color centers produced in potassium bromide by exposure of the crystal at temperature of liquid nitrogen (81 K) to intense penetrating x-rays. ve. band ( vcp See vacuum condensing point. 

Using vacuum condensers (see Section 2.15). These act as selective pumps and should be sized so that the downstream gas ballast pump will not receive more vapor than the amount corresponding to the appropriate vapor tolerance. 

The condensing turbine does not produce exhaust steam. All the turbine exhaust steam is turned into water in a surface condenser. We will study surface condensers in Chap. 18. The surface condenser is just like the sort of vacuum condensers we discussed in Chap. 16, sections on steam jets. The exhaust-steam condenses under a deep vacuum— typically 76 mm Hg, or 0.1 atm. Basically, then, a condensing steam... 

Although the rate of heat transfer to or from fluids is improved by increase of linear velocity, such improvements are limited by the economic balance between value of equipment saving and cost of pumping. A practical rule is that pressure drop in vacuum condensers be limited to 0.5-1. Opsi (25-50 Ton) or less, depending on the required upstream process pressure. In liquid service, pressure drops of 5-10 psi are employed as a minimum, and up to 15% or so of the upstream pressure. 

The utility system has as typical units steam and gas turbines, electric motors, electric generators, fired or waste heat boilers, steam headers at different pressures and auxiliary units (e.g., vacuum condenser, water treater, deaerator), and provides the required electricity, power, and utilities. 

However, droplet systems can enable much higher energy input (via gas phase pressure drop in cocurrent systems) and, as a result, dominate applications where a quick quench is needed. See Examples 21 and 22. Conversely, droplet systems can also be designed for very low pressure drop which is advantageous in applications such as vacuum condensers. 

Ashida, M. (1966) The orientation overgrowth of metal-phthalocyanines on the surface of single crystals. I. vacuum condensed films on muscovite. Bulletin of the Chemical Society of Japan, 39,... 

Porous structure of the outer support surface has been modified by deposition of the additional layer of metal Ni. Two vacuum condensation techniques have been used for nickel deposition dc ion magnetron sputtering and electron beam evaporation. To produce coatings on tubes additional installation for dc sputtering has been designed. 

This experimental assembly is much more complex than the preceding one. The oxide surfaces are ultrathin alumina films grown on NiAl(l 1 0) single crystals, in the preparation chamber following a standard procedure [16]. The alumina films are characterized in situ by AES and LEED. The metal clusters are prepared by vacuum condensation at RT of a metal atoms beam generated by an electron bombardment evaporator calibrated by a quartz microbalance. Metal atoms condense only on the sample through an aperture placed closed to it. After preparation the sample is transferred in the reaction chamber. The characterization of the metal clusters is based on STM observations of deposits performed in the same conditions in another UHV chamber [16]. 

Because of the high conversions in the synthesis, the recycle section of the plant is very small. An evaporation stage with vacuum condensation system produces urea melt with the required concentration either for the Stamicarbon fluidized-bed granulation or for prilling. Process water produced in the plant is treated in a desorbtion/hydrolyzer section. This section produces an effluent, which is suitable for use as boiler feedwater. 

Due to high conversions in the synthesis, the recycle section is very small. An evaporation stage with vacuum condensation system produces urea melt with the required concentration either for granulation or for prilling. 

Pyrolysis reactions of mononuclear carbonyls and low-nuclearity cluster compounds have been used extensively in the syntheses of HNCC of osmium (54, 72,80,95,108), ruthenium (18,20,29), and, more recently, rhenium (2-4). The reactions have been carried out either in inert solvents or, to facilitate the ejection of CO or other volatile ligands, in the solid state under vacuum. Condensation processes under pyrolytic conditions are rarely specific and, as such, lead to the formation of a wide range of products. In order to obtain optimum yields of a particular HNCC, the reaction conditions must be carefully screened. Solution reactions offer advantages such as the ability to monitor the progress of the reaction using IR spectroscopy. As they often give... 

Into a 100-mL reactor, and transferred by vacuum, were placed SO3 (5.6 mmol) and F2C = CFSO,F (9.0 mmol). The reactor was then heated at 120 C for 40 h, which was followed by irap-io-trap vacuum condensation the product was collected in a — 45 C trap. A small amount of yellow oil remained in the reactor and did not vacuum transfer at 22 C. Based on FNMR analysis, the product consisted of sultonc 4, 2-fliioro-2,2-bis(fluorosuIfonyi)acetyl fluoride (5), and the acetyl fluoride 6 in the ratio (4/5/6) 77 20 2.7 the products were separated by preparative GC. 

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