Relative gain volatility

The numerical case given is fgr a 20-tray column with 10 trays in the stripping section. A constant relative volatility of 2 1 used. The column steadystate profile is given in Table 12.3, together with the values of coefficients and the transfer functions in terms of log modulus (decibels) and phase angle (degrees) at frequencies from 0 to 10 radians per minute. The values at zero frequency are the steadystate gains of the transfer functions. 

The distillation column used in this example separated a binary mixture of propylene and propane. Because of the low relative volatility and large number of trays, the dominant time constant is very large (500 minutes). Despite this large time constant, a sampling period of 9.6 minutes gave poor results. The period had to be reduced to 1,8 minutes to get good identification, both dynamic and steadystate gain. 

Another relatively new SPE approach originally developed for the analysis of volatile organic compounds in environmental samples is solid-phase microextraction (SPME). This technique has gained acceptance for a wide variety of additional applications for the isolation of organic compounds from aqueous solu-... 

Wastewater iriiriirnization in batch processes has gained much attention in the very recent past. Mainly 2 reasons lie behind this heightened interest. Firstly, batch operations are inherently flexible, which renders them ideal for volatile conditions that characterize today s markets. Secondly, batch processes tend to produce highly toxic effluent streams, albeit in relatively small quantities in comparison to their continuous counterparts. The stringent environmental conditions militate against the latter characteristic of batch plants, hence the need to eliminate or minimize effluent. 

Other problems may arise if the modeler s objective is to explain or predict the results of an "applications level" experiment (one involving a relatively complex system) that is carried out in the field or, more commonly, the laboratory. First, the conditions assumed to prevail in the experiment may not be the actual ones. For example, the experiment may be thought to be a closed system, when in fact there is loss or gain of volatiles such as carbon dioxide. For another, the walls of the experimental vessel may be thought to be not a factor in the course of reaction when in fact they are via such mechanisms as diffusive absorption or corrosion. 

---