Partial condensers design

More elaborate means have been described for removing the acetone by distillation with relatively little isopropyl alcohol. These include various columns such as a Vigreux13 or a modified Widmer column.10 They are to be recommended when the aldehyde or ketone boils Within 50° of isopropyl alcohol, but are unnecessary under other circumstances. A reflux condenser maintained at constant temperature by boiling methanol has been suggested.6 More convenient than this is the simple but effective partial condenser designed by Hahn.49 An easily constructed modification is illustrated in Fig. 3 (adapted from Organic Syntheses).60 The partial condenser is attached directly to the round-bottomed flask, and ethanol is placed in the inner condensing tube. The... 

The UCB collection and refining technology (owned by BP Chemicals (122,153—155)) also depends on partial condensation of maleic anhydride and scmbbing with water to recover the maleic anhydride present in the reaction off-gas. The UCB process departs significantly from the Scientific Design process when the maleic acid is dehydrated to maleic anhydride. In the UCB process the water in the maleic acid solution is evaporated to concentrate the acid solution. The concentrated acid solution and condensed cmde maleic anhydride is converted to maleic anhydride by a thermal process in a specially designed reactor. The resulting cmde maleic anhydride is then purified by distillation. 

Overhead condensers sometimes need to be located in the stmcture. Usually, partial condensers need to be elevated above the reflux accumulator. Considerable stmcture cost reduction can be achieved if the process can use grade-mounted condensers. Mounting the exchangers at grade may require them to be designed with subcooling so that the reflux accumulator can be located above the condenser. This should be considered as part of the process design. 

Design a partial condenser to cool a mixture of hydrogen chloride-water vapor from 178°F to 90°F using 60 gal per min of chilled water at 70°F The unit is to have the acid mixture in the tubes, because this will allow for a cheaper construction than if this material were in the shell. The tube-side material is to be impervious graphite, and the shell and shell-side baffles are to be steel. The acid vapor is essentially at its dew point. 

The reboiler, and a partial condenser if used, act as equilibrium stages. However, when designing a column there is little point in reducing the estimated number of stages to account for this they can be considered additional factors of safety. 

Gilmore (1963) gives an integrated form of equation 12.57, which can be used for the approximate design of partial condensers... 

As a rough guide, the following rules of thumb suggested by Frank (1978) can be used to decide the design method to use for a partial condenser (cooler-condenser) ... 

Bell, K. J. andGHALY, M. A. (1973) Chem. Eng. Prog. Symp. Ser. No. 131, 69,72. An approximate generalized design method for multicomponent/partial condensers. 

Ward, D. J. (1960) PetroJChem. Eng. 32, C-42. How to design a multiple component partial condenser. 

Process designers sometimes like to use dephlegmators or partial condensers mounted directly in the top of the distillation column when the overhead product is taken off as a vapor. They arc particularly popular for corrosive, toxic, or hard-to-handle chemicals since they eliminate a. separate condenser shell, a reflux drum, and a reflux pump. Comment on the relative controllability of the two process systems sketched below. 

Figure 4. Reformer plant design. Key 1, output cooler 2, partial condenser 3, feedwater heater 4, boiler ...

Column 1 As the base case design in Table 5.3 shows, column 1 has 51 stages, and operates with a partial condenser with a duty of 1.371 MW at the top, and a side condenser with a duty of 8.144 MW at stage 2. It has no reboiler however, it receives a side heat stream with a duty of 15.299 MW to the last stage from section 2 of the plant. The temperature profiles of both columns are shown in Figure 5.9. 

---