Distributed Feed Addition

It is also interesting to note that, from a mathematical point of view, these strange positions of X that may be created through distributed feed addition allow the roots of the DPE to be complex. The profiles are in such cases, of course, still perfectly valid and it is still possible to design a feasible column if the roots of the DPE happen to be complex in a particular CS. 

What should be clear from the illustrations presented in Ingures 6.5 6.8 is that the concept of distributed feed addition columns presents unique opportunities to the designer. Each stream addition gives the designs an additional degree of freedom that may be used to manipulate profiles to suit the separation. However, although... 

Thus, if we could improve either of these cost measures, distributed feed addition will certainly be a worthwhile consideration. First, let us consider whether a reduction in the reflux ratio may be achieved. 

Product Distribution. In addition to ethylene, many by-products are also formed. Typical product distributions for various feeds from a typical short residence time furnace are shown in Table 5. The product distribution is strongly influenced by residence time, hydrocarbon partial pressure, steam-to-od ratio, and coil outlet pressure. 

Center for veterinary Medicine (CVM) Releases guideline for manufacture and distribution of drugs and feed additives intended for animals www.fda.gov/cvm /... 

This principle may also be illustrated by some real cases. In the codimerization of propene and hexene it is important primarily to minimize the dimerization of the reactive propene. In order to favor the codimerization, a stage injection of propene according to the principle in Fig. 1 was therefore performed [2]. A similar process design with distributed additions of chlorine was applied in the chlorination of propene to allyl chloride in order to suppress different side reactions [3]. For liquid-phase processes, a distributed feed to the cascade of stirred reactors was a more natural variant. This was applied in the sulfuric acid alkylation of / obutane, where the olefin feed has to be subdivided due to selectivity reasons and the goal was to reach a desired octane number of the product [4]. 

Estimated end-use distribution of arsenic in the United States was 70% (16,000 tons as elemental arsenic) in industrial chemicals (mainly as wood preservatives), 22% (5200 tons) in agricultural chemicals (mainly as herbicides and desiccants), 4% (900 tons) in glass manufacture, 3% (700 tons) in nonferrous alloys and 1% (300 tons) for other purposes (animal feed additives, pharmaceuticals etc.) in 1989. Estimated end-use of arsenic in Japan was 35% (230 tons) for refining of zinc, 34% (220 tons) for glass manufacture, 15% (100tons) for electronics as ultrapure arsenic metal and 15% (lOOtons) for wood preservatives and agricultural chemicals in 1988. 

Comment 2 The only additional information that is needed if the number of components is larger than 3 is the mole fraction of those components in the feed. The initial guess for the distribution of additional components in the product streams is determined by the following rules ... 

Development of analytical methodology for 62,63 fast separation of As species. Application for studies on distribution and possible transformation of phenylarsonic compounds used as poultry and swine feed additives presented different wine samples analyzed [As(in) the only species found] and arsenosugars determined in kelp samples... 

Ueberschar KH, Matthes S (2004) Dose-response feeding study of chlorinated paraffins in broiler chickens effects on growth rate and tissue distribution. Eood Addit Contam 21 943-948... 

Because of their relative simplicity, the Underwood minimum reflux equations for Class 2 separations are widely used, but too often without examining the possibility of nonkey distribution. In addition, the assumption is frequently made that (/ )min equals the external reflux ratio. When the assumptions of constant relative volatility and constant molal overflow in the regions between the two pinch-point zones are not valid, values of the minimum reflux ratio computed from the Underwood equations for Class 2 separations can be appreciably in error because of the sensitivity of (12-34) to the value of q as will be shown in Example 12.5. When the Underwood assumptions appear to be valid and a negative minimum reflux ratio is computed, this may be interpreted to mean that a rectifying section is not required to obtain the specified separation. The Underwood equations show that the minimum reflux depends mainly on the feed condition and relative volatility and, to a lesser extent, on the degree of separation between the two key components. A finite minimum reflux ratio exists even for a perfect separation. 

Examples of such complex distillation structures are thus columns that have more than one feed point and/or more than two product streams, like distributed material addition/removal columns, and thermally coupled columns. Obviously, as the complexity of the distillation structure increases, so does the design itself thereof. This chapter will, as an introduction to complex column design, treat the design of elementary complex columns such as distributed feed and sidestream withdrawal columns, and side rectifiers, and strippers, before discussing more intricate complex columns like fully thermally coupled columns (sometimes referred to as the Petlyuk and Kaibel columns) in the subsequent chapter. Despite... 

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