Condensers - Process Design Practice - Lecture Slides, Slides of Process Engineering

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Distillation Modeling

Overview

•^

Purpose of Overhead Condensers–^

Provide reflux flow to the top of a column and acts asan additional theoretical stage above the trays/packing

•^

Types of Condensers–^

Knock-back reflux

-^

Total condenser

-^

Partial condenser^ Proper condenser design is critical to the

optimum operation of a column!

Partial Condenser

• Used when vapor product isrequired, or if non-condensiblegases are present in theoverhead product.• Controlling the vapor streamsplit can be challenging.• Condenser can be in thevertical or horizontal position. -^ Horizontal – Process onthe shell side. -^ Vertical – Process is onthe tube side. - Elevation is not critical.

LiquidDistillate VaporDistillate

Total Condenser

• Total condensers are used whenno non-condensable gases arepresent.• As with other condensers, verticalor horizontal operation is possible.• Elevation is not critical for a totalcondenser.• Subcooling of the reflux can be aproblem with overheadcondensers, especially with verticaldesigns.

LiquidDistillate

Condensers in ASPEN Plus

Air-Cooled Heat Exchangers

V FD

V FD

Process In

Process Out

Design Equations:

13 Pr Re^

 

^

m C k OD U

)

(^

,

,^

in Air out Air

lm^

T

T Cp m T A U Q^



     ^



Tube Detail

Note:

The surface area,

A, includes the area of the fins!

C and

m are parameters based on the size of the fin.

•^

Typical Air-Cooled Condenser

Air-cooled HX are primarilyused when no other coolingutilities are available on site