Partial condenser

On introducing acetochloroglucose into an alkaline solution of a monosaccharide in aqueous alcohol, apart from their condensation, partial removal of acetyl groups, in the form of ethyl acetate, occurs. This was the first indication of transesterifico-tion by alkoxide (1902), a reaction that later achieved great importance. 

In controlling the pressure of a column, the key pieces of equipment are the condenser and accumulator. First, the overhead vapors enter the condenser (partial or total), and next, the liquid condensate is collected in an accumulator vessel. Some of the accumulated condensate is returned to the column as reflux, while the remainder is withdrawn as overhead product (distillate). 

Number of ideal stages Total condenser Partial reboiler Stage holdup Condenser holdup Maximum reboiler duty... 

A simple total-condensation, partial take-off column with... 

Volatilization from batch and glass is mainly responsible for particulate emissions vapours condense partially and are settled in regenerators and flue ducts, but very fine condensates succeed in passing into the stack. The content of sulphur oxides (SO2 + 5 - 11 % SO3) depends on the type of fuel and batch composition the content of nitrogen oxides (N2O, NO, NO ) is a function of flame temperature in the furnace. In all-electric cold-top furnaces, atmospheric pollution by the substances mentioned above is virtually non-existent. 

The submitter used an insulated column with a 38 by 1.1 cm. section packed with H-in. copper helices made of No. 26 B S gauge copper wire. He states that a column packed with glass helices is unsatisfactory. The checkers used a 100 by 1.7 cm. Vigreux column. Either type of column shorfld be equipped with a total condensation, partial take-off head. 

Simple distillation Total (liquid product) condenser Partial (liquid product) reboiler 152 Stages Feeds to stages 43... 

For a column whose geometry [the total number of stages, the feed plate locations, and the type of condenser (partial or total)] and feed have been specified, the remaining variables to be specified are as follows ... 

A sketch of the condenser-accumulator section for the general case where two liquid phases and one vapor phase are formed in the accumulator is shown in Fig. 6-10. The functions and variables selected depend upon the particular set of specifications made on the column. Three cases are considered. All of the specifications are the same for each case except for the specification of the type of condenser (partial or total) and the product specifications such as Lx and L v or Qc and QR. In addition to these two specifications, the fractions a and p of the liquid streams withdrawn from the system may be specified. Generally, a and P are set equal to 0 or 1 such that one phase is returned to the column as reflux and the other phase is withdrawn as a product. 

Let the total number of stages be denoted by N which includes the reboiler and the condenser, partial or total. The number of plates is then equal to N — 2 which is also equal to k2 for a conventional column. The upper and lower bounds on kx are denoted by klfJ and klL, respectively. Similarly, the upper and lower bounds on the total number of plates are denoted by k2V and k2L> respectively. For example, values of k2 greater than 50 or 100 are seldom encountered, and the designer might well take kl(J = k2U = 100 (or 200). The lower bounds might well be taken to be klL = k2L = 1. 

The operating line for the rectifying section then intersects the diagonal at point (jcc.xtd). This is true for either a partial or a total condenser. (Partial condensers are discussed in the next section.)... 

As an exercise, the reader is invited to demonstrate that both for condenser and reboiler, the degrees of freedom are (A +4), identical with a flash. Typically, the specifications are input stream N. + 2) variables plus two others. Outlet pressure is usually imposed. The remaining variable may be liquid or vapour fraction, including bubble-point liquid (1=1), dew-point vapour (1=0), or sub-cooled liquid or superheated vapour (unusual). The above specifications enable to compute the duty Q, but this may be given also as specification. Note also that in steady state flowsheeting the reflux drum is included in the simulation of condenser. The type of condenser (partial, total, or sub-cooled liquid), as well as the type of reboiler (kettle or thermosyphon) does not change the analysis. 

Distillation (one inlet stream, partial condenser, partial reboiler, both liquid and vapor distillates)... 

---