Controlling Crystallization

Com symp soflds are also dry products, have a smaller average size, and are comparatively sweeter (12). Both maltodextrins and com symp soflds are used to prevent caking enhance dispersibiUty and solubiUty provide body or bulk impart deskable texture bind, carry, and protect flavors control extmsion expansion provide viscosity form films and coatings provide an oxygen barrier inhibit crystallization control sweetness improve sheen improve organoleptic characteristics slow meltdown and improve freeze—thaw stabiUty. 

The combination of non-ideal phase behaviour of solutions, the non-linearity of particle formation kinetics, the multi-dimensionality of crystals, their interactions and difficulties of modelling, instrumentation and measurement have conspired to make crystallizer control a formidable engineering challenge. Various aspects of achieving control of crystallizers have been reviewed by Rawlings etal. (1993) and Rohani (2001), respectively. 

Chang, C.-T. and Epstein, M.A.F., 1982. Identification of batch crystallization control strategies using characteristic curves. American Institute of Chemical Engineers Symposium Series, 78(215), 68-75. 

Thermodynamic inhibitors Antinucleants Growth modifiers Slurry additives Anti-agglomerates Methanol or glycol modify stability range of hydrates. Prevent nucleation of hydrate crystals. Control the growth of hydrate crystals. Limit the droplet size available for hydrate formation. Dispersants that remove hydrates. 

Figure 3.10 Typical STM experimental arrangement with negative feedback circuit to the piezoelectric crystal controlling movement in the z-direction.

In the measurement technique, which has been used on D3 for many years, the ratio of the time spent counting with the cryoflipper in (+) or (-) mode is controlled by a quartz crystal controlled oscillator with a highly stable output frequency / of 1 MHz. There are two scalers to count the detector pulses (+ and - states), a single monitor scaler and a single time scaler used to end the measurement when the total time is reached (precision of 1 ms). 

The detector signal is conditioned through a single channel pulse height analyzer whose output pulses are fed to a scaler-timer in the single crystal controller. 

Takada, M. (2004) PhD Thesis, Crystallization control and foam processing of semi-crystalline... 

In all these reactions, crystallographic studies demonstrated the crystal control responsible for formation of the observed products. Thus, the prereaction ketone oxygen-steroidal hydrogen distance is in all cases 3.4 0.5 A, the ketonic carbon-steroidal (to-be-attacked) carbon distance is of the order of 4 A, and the... 

Ice Crystal Growth. In order to quantify these results for the production of large disc and spherical crystals, seversd batch experiments on 6% lactose solutions were undertaken. The experimental conditions and results are shown in Table II. In these experiments, nuclei were generated at -2.5 C (except for Run Sa at -4.0°C) and input to the batch crystallizer controlled at various refirigerant temperatures. As these crystals grew, the total crystal surface area was controlled manually in order to maintain a heat balance for a constant value of the refrigerant temperature. Slurry removal rate for these experiments... 

Wax Crystal Control Nanocomposites Stimuli-Responsive Polymers... 

Figure 4-35 Concentration profile during melting of two crystals controlled by (a) interface reaction and (b) diffusion in the melt. The open circles indicate melt compositions in equilibrium with titanite (position A in Figure 4-34) and with anorthite (B in Figure 4-34).

Q. Explain the difference between a free-running and a crystal-controlled radiofrequency generator 4.4.3 Sample Introduction... 

The second approach is thru the modification of the Compn B formulation and the elimination of cast charge defects, especially at the interface with the projectile base. Studies have centered primarily in the utilization of crystal control agents — polymeric materials, HNS, etc, the finish on the interior of the projectile, and on controlled loading cooling processes... 

The pulses are provided by a precision bipolar voltage source, which is switched into the input of the pulsing amplifier by the switch at point A in the circuit. A very accurate crystal-controlled timing circuit (not shown) drives the switch to ensure that the pulses are symmetrical. The pulsing amplifier inverts the signal as shown by waveform B and supplies current to the cell. The cell current is amplified by the current follower, the output of which is illustrated by waveform C. 

Digital timers of excellent quality that are based on crystal oscillators are available. The resonant frequency of such oscillators is temperature dependent and subject to aging effects, but the state of the art is highly developed. Crystal-controlled clock oscillators having a maximum error of 1 ppm at 25°C are commercially available from a number of manufacturers. Some units are tem-... 

Costa, F. R., Saphiannikova, M., Wagenknecht, U., and Heinrich, G., Layered double hydroxide based polymer nanocomposites, Adv. Polym. Sci. (2008), 210(Wax Crystal Control Nanocomposites Stimuli-Responsive Polymers), 101-168. 

A 1- to 2-kW radio frequency power supply, either free-running or crystal-controlled, drives current through a water- or air-cooled copper tube that acts as the induction coil (often called a load coil). The oscillating current through the load coil produces an oscillating electromagnetic field. 

Recently [38], Prosonix has been launched as a new American company with the aim of exploiting academic technology to apply ultrasonics to crystallization control and process intensification on a commercial scale. 

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