Surface condensers example

Mg. 11, 56, 17 (Davies types) and Fig. 11, 56, 18 (double coil type) are examples of efficient double surface condensers. Fig. 11, 56, 19 depicts a screw type of condenser (Friedrich pattern) the jacket is usually 10, 15 or 25 cm. long and the cone and sockets are fil9 or 24 this highly efficient condenser is employed for both reflux and for downward distillation. 

However, it is not practical to set the gas temperature in steady state without equally setting the temperature of the surface and bulk phases hounding the gas. Consideration of the response of the system as a vacuum environment can then provide a sufftciendy precise prediction of the pressure P and the surface coverage 9 at temperature Tfor molecules of a known species in a known state on a known surface. For example, an isotherm is estabhshed between the surface of the condensed and the gaseous phases, depending, eg, on the heat of desorption. For submonolayer coverage on a... 

Example 3-8 Closed System Steam Surface Condenser NPSH Requirements, Use Figure 3-44... 

Example 6-9 Ejector Load For Steam Surface Condenser... 

Example 3-6 NPSH Available in Vacuum System, 191 Example 3-7 NPSH. Available in Pressure System, 191 Example 3-8 Closed System Steam Surface Condenser NPSH Requirements, 191 Example 3-9 Process Vacuum System, 192 Reductions in NPSHr, 192 Example 3-10 Corrections to NPSHr for Hot Liquid Hydrocarbons and Water. 192 Example 3-9 Process Vacuum System, 192 Example 3-10 Corrections to NPSHr for Hot Liquid Hydrocarbons and Water, 192 Example 3-11 Alternate to Example 3-10, 194 Specific Speed,... 

The design of this double surface condenser can be changed as desired for example, FigURE 62, V, shows a double surface reflux condenser which may be made by modifying the above general procedure. 

Condensate pumps serving surface condensers have a common problem. Their suction is under a vacuum. For example, let s assume the following for Fig. 18.3 ... 

After distillation, heat transfer is the most important operation in a process plant. Most of the heat transfer in chemical plants and petroleum refineries takes place in shell-and-tube heat exchangers. The surface condenser we discussed in Chap. 18 is an example of a shell-and-tube heat exchanger. 

Reactions proceed faster and more smoothly when the reactants are dissolved, because of diffusion. Although reactions in the solid state are known [1] they are often condensations in which a molecule of water is formed and reaction takes place in a thin film of water at the boundary of the two solid surfaces. Other examples include the formation of a liquid product from two solids, e.g. dimethylimidazolium chloride reacts with aluminum chloride to produce the ionic liquid, dimethylimidazolium tetrachloroaluminate [2]. It is worth noting, however, that not all of the reactant(s) have to be dissolved and reactions can often be readily performed with suspensions. Indeed, so-called sol-id-to-solid conversions, whereby a reactant is suspended in a solvent and the product precipitates, replacing the reactant, have become popular in enzymatic transformations [3]. In some cases, the solvent may be an excess of one of the reactants. In this case the reaction is often referred to as a solvolysis, or, when the reactant is water, hydrolysis. 

The remarks set out under the previous heading also apply to advanced glassblowing, except that the standards sought are higher and the glassware made will be of greater complexity. For example, the students should learn to make double surface condensers of various patterns, and, if required, should prepare and assemble the components of the glassware for a vacuum line. It is also desirable that they receive some instruction in the use and maintenance of the vacuum apparatus. 

In what follows, heterogeneous transformations are understood as chemical or physical-chemical transformations that take place on some surfaces, for example, on interfaces or surfaces possessing catalytic properties. This wide understanding of the term heterogeneous transformation includes surface catalytic reactions, adsorption and desorption on solid and fluid surfaces, dissolving of crystals in fluid, electrochemical reactions on the surface of an electrode in electrolyte, sublimation and condensation, sedimentation of aerosols and colloids, etc. Chemical transformations taking place in the bulk of fluid will be called homogeneous transformations or volume chemical reactions. 

Alkali metals uniformly distributed over a surface often act as promoters in the kinetics of catalytic reactions. Their high mobility can give rise, on the other hand, to pattern formation. In the H2 + O2 reaction on a Rh(l 10) surface, for example, preadsorbed K atoms may condense reversibly into mesoscopic islands where they interact with O atoms and may then become subject of propagating reaction fronts [27,28]. Differences in the mobility and bonding strength of K on the O-rich and reduced surface regions are decisive factors for this type of concentration pattern formation. 

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