Styrene Stripping Section

The SPS powder is dried in the dryer. Under high temperatures, SPS powders melt and the adhesion problem occurs in the dryer [12], Under low temperatures, the drying rate is low. Therefore, drying temperature and pressure are important. 

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The rate-based model gave a distillate with 0.023 mol % ethylbenzene and 0.0003 mol % styrene, and a bottoms product with essentially no methanol and 0.008 mol % toluene. Miirphree tray efficiencies for toluene, styrene, and ethylbenzene varied somewhat from tray to tray, but were confined mainly between 86 and 93 percent. Methanol tray efficiencies varied widely, mainly from 19 to 105 percent, with high values in the rectifying section and low values in the stripping section. Temperature differences between vapor and liquid phases leaving a tray were not larger than 5 F. 

A packed distillation column for the separation of ethylbenzene(l) and styrene(2) was designed in Example 14.3.3. The packing is Koch Flexipac II with characteristic dimensions in Table 14.6. Estimate the mass transfer coefficients and the heights of transfer units for the rectifying and stripping sections in this column. 

The engineering analysis and design of these operations addresses questions which are different than those addressed in connection with the shaping operations. This is illustrated in Fig. 1 which is a flow sheet, cited by Nichols and Kheradi (1982), for the continuous conversion of latex in the manufacture of acrylonitrile-butadiene-styrene (ABS). In this process three of the nonshaping operations are shown (1) a chemical reaction (coagulation) (2) a liquid-liquid extraction operation which involves a molten polymer and water and (3) a vapor-liquid stripping operation which involves the removal of a volatile component from the molten polymer. The analysis and design around the devolatilization section, for example, would deal with such questions as how the exit concentration of... 

Reactor effluent is cooled in a series of exchangers (3) to recover waste heat and to condense (4) the hydrocarbons and steam. Uncondensed offgas—primarily hydrogen—is compressed (5) and then directed to an absorber system (6) for recovery of trace aromatics. Following aromatics recovery, the hydrogen-rich offgas is consumed as fuel by process heaters. Condensed hydrocarbons and crude styrene are sent to the distillation section, while process condensate is stripped (7) to remove dissolved aromatics and gases. The clean process condensate is returned as boiler feedwater to offsite steam boilers. 

Figure 12.1 Flow diagram of the monomer purification section. V-100 styrene storage tank V-110 oxygen stripping column V-120 alumina column V-130 hydrogenation column V-140 surge vessel F-140 filter V-150 styrene feed tank.

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