Decanation

Example 4.1 Monochlorodecane (MCD) is to be produced from decane (DEC) and chlorine via the reaction... 

What is the minimum selectivity of decane which must be achieved for profitable operation The values of the materials involved together with their molecular weights are given in Table 4.1. 

Four possible arrangements can be considered a. Complete conversion of both feeds. Figure 4.7a shows the most desirable arrangement complete conversion of the decane and chlorine in the reactor. The absence of reactants in the reactor effluent means that no recycles are needed. 

Although the flowsheet shown in Fig. 4.7a is very attractive, it is not practical. This would require careful control of the stoichiometric ratio of decane to chlorine, taking into account both the requirements of the primary and byproduct reactions. Even if it was possible to balance out the... 

Note that no attempt has been made to separate the chlorine and decane, since they are remixed after recycling to the reactor. 

In practice, there is likely to be a trace of decane in the reactor eflfluent. However, this should not be a problem, since it can either be recycled with the unreacted chlorine or leave with the product, monochlorodecane (providing it can still meet product specifications). 

Again, in practice, there is likely to be a trace of chlorine in the reactor effluent. This can be recycled to the reactor with the unreacted decane or allowed to leave with the hydrogen chloride byproduct (providing this meets with the byproduct specification). 

It cannot be said at this stage exactly how great an excess of decane would be required in order to make Fig. 4.7d feasible. This would have to be established experimentally, but the size of the excess does not change the basic structure. 

An arrangement is to be chosen to inhibit the side reaction, i.e., give low selectivity losses. The side reaction is suppressed by starving the reactor of either monochlorodecane or chlorine. Since the reactor is designed to produce monochlorodecane, the former option is not practical. However, it is practical to use an excess of decane. 

The last of the four flowsheet options generated above, which features excess decane in the reactor, is therefore preferred (see Fig. 4.7[Pg.104]

Now the process must convert at least 72 percent of the decane to monochlorodecane. 

Estimate the surface tension of n-decane at 20°C using Eq. 11-39 and data in Table II-4. 

Using Eqs. VI-30-VI-32 and data from the General References or handbooks, plot the retarded Hamaker constant for quartz interacting through water and through n-decane. Comment on the relative importance of the zero frequency contribution and that from the vuv peak. 

A thin film of hydrocarbon spread on a horizontal surface of quartz will experience a negative dispersion interaction. Treating these as 1 = quartz, 2 = n-decane, 3 = vacuum, determine the Hamaker constant A123 for the interaction. Balance the negative dispersion force (nonretarded) against the gravitational force to find the equilibrium film thickness. 

From the variation of contact angle with SAM composition in Fig. X-3, what do you think the measuring liquid is What would the plot in Fig. X-3 look like if, say, n-decane were used instead ... 

Fig. XII-12. Top friction traces for two calcium alkylbenzenesulfonate monolayers on mica where the monolayers are in a liquidlike state. A—in inert air atmosphere B—in saturated decane vapor. Bottom contact radius-load curves showing adhesion energy measured under the same conditions as the friction traces. (From Ref. 53.)...

As an example figure B 1.14.13 shows the droplet size distribution of oil drops in the cream layer of a decane-in-water emulsion as determined by PFG [45]. Each curve represents the distribution at a different height in the cream with large drops at the top of the cream. The inset shows the PFG echo decay trains as a fiinction of... 

Figure Bl.14.13. Derivation of the droplet size distribution in a cream layer of a decane/water emulsion from PGSE data. The inset shows the signal attenuation as a fiinction of the gradient strength for diflfiision weighting recorded at each position (top trace = bottom of cream). A Stokes-based velocity model (solid lines) was fitted to the experimental data (solid circles). The curious horizontal trace in the centre of the plot is due to partial volume filling at the water/cream interface. The droplet size distribution of the emulsion was calculated as a fiinction of height from these NMR data. The most intense narrowest distribution occurs at the base of the cream and the curves proceed logically up tlirough the cream in steps of 0.041 cm. It is concluded from these data that the biggest droplets are found at the top and the smallest at the bottom of tlie cream.

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