Condensation single vapor

Only parts needed above but for the vapor-phase reactor are listed here. Most of the description for the installation for methanol synthesis experiments (Figure 4.2.1) holds for this installation, too. In the mentioned unit, product was blown down while still hot, thus keeping all product in a single vapor phase. This simplifies material balance calculations. When avoiding condensation is difficult, cooling and separation becomes necessary. This method was used in the cited AIChEJ publication. 

This section describes the phase change process for a single component on a molecular level, with both vaporization and condensation occurring simultaneously. Molecules escape from the liquid surface and enter the bulk vapor phase, whereas other molecules leave the bulk vapor phase by becoming attached to the liquid surface. Analytical expressions are developed for the absolute rates of condensation and vaporization in one-component systems. The net rate of phase change, which is defined as the difference between the absolute rates of vaporization and condensation, represents the rate of mass... 

With a mole fraction given by point (b) we repeat the process at a composition to the left of (richer in Ar than) point (c). The changes that occur can be followed by referring to the lower (b) set of cylinders. At (1) we are below the vapor line and only a gaseous mixture is present. In (2) we have intersected the vapor line and liquid is present. As the pressure increases, more condensation occurs as shown in (3). With continued compression, however, the liquid level shrinks as shown in (4) until we again intersect the vapor line where the liquid disappears and only a single vapor phase remains as shown in (5).n... 

When a saturated vapor is brought into contact with a cool surface, heat is transferred to the surface and a liquid condenses. The vapor may consists of a single substance or a mixture, some components of which may be non-condensable. 

The simplest case of practical interest to us involves the condensation of a single vapor in the presence of a noncondensing gas. Condensation of steam in the presence of air is an important practical application. The equations developed in the preceding section may also be used here to determine the rate of condensation of the vapor. However, some simplifications are possible since the liquid phase will be a pure component. 

Algorithm 15.3 Condensation of Single Vapor in the Presence of Inert Gas... 

A wide variety of other geometrical configurations have been proposed for enhancing heat transfer in single-phase, condensing, and vaporizing systems. Extended treatments of many of these geometries are available in the literature [5-7]. 

The J shell is mainly used for condensation of low-pressure vapor because it splits the flow, reducing velocities and resulting in lower pressure drops. It is also sometimes used for single-phase flow. The J shell can also be used with the two nozzles on top, and two J shells can be mounted nozzle to nozzle in series for long-condensing-range vapors. 

Nonequilibrium, or film, methods provide physically realistic formulations of the problem that yield more accurate local coefficients at the expense of complexity. Colburn and Hougen [77] developed a trial-and-error solution procedure for condensation of a single vapor mixed with a noncondensable gas. Colburn and Drew [203] extended the method to include condensation of binary vapor mixtures (with no noncondensables). Price and Bell [204] showed how to use the Colburn and Drew [203] method in computer-assisted design. 

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