Ideal contact stages

Absorption takes place in either staged or plate towers or continuous or packed contactor. However, in both cases the flow is continuous. In the ideal equilibrium stage model, two phases are contacted, well mixed, come to equilibrium, and then are separated with no carryover. Real processes are evaluated by expressing efficiency as a percentage of the change that would occur in the ideal stages. Any liquid carryover is removed by mechanical means. 

Each of the two contacting phases (gas and solid) can be either in plug flow (perfectly staged) or backmixed (perfectly mixed) condition. At this stage of reactor selection it is only necessary to specify what the ideal contacting pattern ought to be the technical limits of feasibility are taken into account in a subsequent analysis. 

In entrainer sublimation, an entrainer gas is blown into the vaporisation chamber of a sublimer in order to increase the vapour flowrate to the condensing equipment, thereby increasing the yield. Air is the most commonly used entrainer, though superheated steam can be employed for substances such as anthracene that are relatively insoluble in water. If steam is used, the vapour may be cooled and condensed by direct contact with a spray of cold water. Although the recovery of the sublimate is efficient, the product is wet. The use of an entrainer gas in a sublimation process also provides the heat needed for sublimation and an efficient means of temperature control. If necessary, it may also provide dilution for the fractional condensation at the desublimation stage. Entrainer sublimation, whether by gas flow over a static bed of solid particles or through a fluidised bed, is ideally suited to continuous operation. 

Since the strain arising from an ideal sharp indenter cannot be wholly elastic (as is the case with a blunt indenter), a number of new specific features of failure of a particular material may arise, especially in the early stages of crack formation under the influence of surface penetration at low loads. It is reasonable to suppose at the same time that as the crack region extends widely below the contact zone, the influence of indenter geometry should become significant. 

Parastiilation. This relatively new approach to distillation, as proposed by A.F..O. Jenkins in 1983. is a method for multistage, counter-current contact between vapor and liquid and is reputed to provide 33 3 more ideal stages than traditional factional distillation at the same tray spacing. The... 

Ideal stage Hypothetical device in which gas and liquid are perfectly mixed, are contacted for a sufficiently long... 

---