Figure 835 case stuoy tfo

(ßflS6D OKJ REF ü) CONDENSATE TEMPERATURE CONTROL

CASE STUDY No. 6 Hot Vapor Bypass Problem

INSTALLATION A hydrocarbon column equipped with a submerged !

condenser and an elevated reflux drum (Figure 8.3.6). The control j system in similar to that shown in Figure 17.5D in Reference 12. j

PROBLEM Pressure fluctuations and inability to keep column pressure | constant. ;

ANALYSIS The cause was diagnosed to be mixing of liquid, which left the condenser subcooled, with vapor. Collapse of vapor took place at the point of mixing. With changes in subcooling, overhead temperature and rate of condensation, the rate of vapor collapse would change, causing pressure fluctuations and control valve !

hunting.

SOLUTION The liquid and vapor lines were separated. The vapor line was modified so that it introduced the vapor into the top of the reflux drum. The liquid line was separated from the vapor line, and was extended into the bottom of the reflux drum. These changes completely solved the problem.

LI&uiD

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