Solution self-flow

Titanium tetrachloride can also be purified from impurities by the continuous technique. The installation for continuous purification consists of several vertical pipe coolers. Liquid products of the reaction are sent into the first cooler, which is located a little higher than the rest, where the mixture is cooled at agitation to -3 - -5°C. After that, the mixture is abruptly cooled to -20 - -23.5 °C the solution deposits crystals of Si2Cl6 and VOCI3. The deposited crystals remain in the primary cooler, and the solution self-flows into the secondary coolers, where it is gradually cooled from -23 to -27 °C titanium tetrachloride deposits as white sediment. It is collected in the secondary coolers and washed with water. The TiCl4 thus purified is 99.92% pure. 

The first rectification stage. From collector 10 the mixture of methyl-chlorosilanes is periodically fed into pressure container 11, from where at 50-65 °C it is sent through heater 12 (by self-flow) onto the feeding plate of rectification tower 13. From the tower the tank liquid (methyltrichloro-silane, dimethyldichlorosilane and tank residue) flows into tank 14, where the temperature of 80-90 °C is maintained, and from there is continously poured into collector 22. After the tower, vapours of the head fraction at a temperature below 58 °C, consisting of the rest of methylchloride, di- and trichlorosilane, dimethylchlorosilane, methyldichlorosilane and the azeotropic mixture of silicon tetrachloride and trimethylchlorosilane are sent into refluxer 15, cooled with water, and into refluxer 16, cooled with salt solution (-15 °C). After that, through cooler 17 the condensate is gathered in receptacle 19. Volatile products, which did not condense in reflux-ers 15 and 16, are sent into condenser 18 cooled with Freon (-50 °C). There they condense and also flow into receptacle 19. As soon as it is accumulated, the condensate is sent from receptacle 19 into collector 20. 

Separation of head fractions. The head fraction, which is obtained at the first stage of continuous rectification of methylchlorosilanes, from collector 20 self-flows into tank 44. The temperature in the tank in the beginning of the process is maintained at 60-70 °C, and at the end it should be from 90 to 95 °C. Vapours from the tank rise up tower 40 and enter reflux-ers 39, cooled with water and salt solution (-15 °C) from there, part of condensate is returned to reflux tower 40, and the rest is sent through cooler 38 into receptacles 41 and fed into collectors 43. 

The reaction gases from the higher part of reactor 5 enter filter 6, then cooler 7, cooled by salt solution after that, the abgases enter the abgase purification unit (not shown in the diagram). The condensate from the cooler self-flows into receptacle 8 and is poured into tanks 9 as it accumulates. The average composition of the condensate is (%) ... 

From container 18 dimethyldichlorosilane is sent into batch box 1 placed over apparatus 2, where a 2% solution of the initiator in dimethyldichlorosilane is prepared. Apparatus 2 is an enameled flask with an agitator and a filling hatch. While the agitator operates, one sends there dimethyldichlorosilane and adds the initiator solution in the amount necessary to form a 2% solution. After 30 minutes of agitation at 20 °C the mixture of dimethyldichlorosilane and initiator is poured into intermediate container 17, from where it is periodically pumped into pressure batch box 4. After that, the mixture self-flows through rotameter 6 into chlorinator 5. The chlorinator is a steel cylindrical apparatus with a heating jacket and a thermometer pocket the lower part of the apparatus contains a distribution device which feeds chlorine. The temperature in the chlorinator is maintained within 65-70 °C and regulated with vapour sent into the jacket of the apparatus and with the speed at which chlorine is fed. 

The reaction of heterofunctional condensation is carried out in reactor 5, which is a steel enameled apparatus with a water vapour jacket and an anchor agitator. Reactor 5 is loaded at a residual pressure of 730 200 GPa with a,eo-dihydroxydiphenylsiloxane, the product of dihydroxydiphenylsilane condensation a calculated amount of the toluene solution of triace-toxymethylsilane self-flows at agitationffom batch box 6. 

With nanospray, the spray tip has a much smaller diameter. Also, for the by far most often used nonviscous solutions, the flow is not a forced flow due to a driven syringe as used in ESI (see Figure 1.2a). Instead, the entrance end of the spray capillary is left open and a self-flow results, which is due to the pull of the applied electric field on the solution at the capillary tip (see Section 1.2.2). This self-flow is controlled by the diameter of the tip of the spray capillary. 

Similarity Variables The physical meaning of the term similarity relates to internal similitude, or self-similitude. Thus, similar solutions in boundaiy-layer flow over a horizontal flat plate are those for which the horizontal component of velocity u has the property that two velocity profiles located at different coordinates x differ only by a scale factor. The mathematical interpretation of the term similarity is a transformation of variables carried out so that a reduction in the number of independent variables is achieved. There are essentially two methods for finding similarity variables, separation of variables (not the classical concept) and the use of continuous transformation groups. The basic theoiy is available in Ames (see the references). 

The beauty of the reptation model is that it is able to make predictions about molecular flow both in solution and at fracture by assuming that the molecules undergo the same kind of motions in each case. For both self-diffusion in concentrated solutions and at fracture, the force to overcome in pulling the polymer molecule through the tube is assumed to be frictional. 

The chip micro reactor ([R 6]) was only one part of a complex serial-screening apparatus [20]. This automated system consists of an autosampler (CTC-HTS Pal system) which introduces the reactant solutions in the chip via capillaries. A pumping system (p-HPLC-CEC System) serves for fluid motion by hydro dynamic-driven flow. A dilution system [Jasco PU-15(5)] is used for slug dilution on-chip. The detection system was a Jasco UV-1575 and analysis was carried out by LC/MS (Agilent 1100 series capLC-Waters Micromass ZQ). All components were on-line and self-configured. 

A typical example is the protonation of tetraphenylporphirin (TPP) at the dodecane-acid solution interface. The interfacial protonation rate was measured by a two-phase stop flow method [6] and a CLM method [9]. In the former method, the stagnant layer of 1.4 jxm still existed under the highly dispersed system. In the CLM method, the liquid membrane phase of 50-100 /am thickness behaved as a stagnant layer where the TPP molecule has to migrate according to its self-diffusion rate. 

Figure 4 shows the application (6) of potentials to the Pt and Au electrodes of the sandwich (vs. a reference electrode elsewhere in the contacting electrolyte solution) so that they span the E° of the poly-[Co(II/I)TPP] couple (Fig. 4B). There is a consequent redistribution of the concentrations of the sites in the two oxidation states to achieve the steady state linear gradients shown in the inset. Figure 4C represents surface profilometry of a different film sample in order to determine the film thickness from that the actual porphyrin site concentration (0.85M). The flow of self exchange-supported current is experimentally parameterized by applying Fick s first law to the concentration-distance diagram in Fig. 4B ...

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