Crystal processing technology

When paraxylene content in the feed is enriched above equilibrium, for example, streams originating from selective toluene conversion processes, the proprietary crystallization process technology is even more economical to produce high-purity paraxylene product at high recoveries. The process technology takes advantage of recent advances in crystallization techniques and improvements in equipment to create this economically attractive method for paraxylene recovery and purification. 

Talanin, V.I. Talanin, I.E. Ustimenko N.Ph. (2011b). A new method for research of grown-in microdefects in dislocation-free silicon single crystals. Journal of Crystallization Process Technologys, Vol.l, Nq 2, pp. 13-17, ISSN 2161-7678. 

Y. Sato, 04 Newest Liquid Crystal Process Technology, 78 (2008)... 

Currendy, about 40% of the PX produced woddwide uses crystallization technology. A number of crystallization processes have been commercialized over the years. The more common ones are those developed by Chevron, Kmpp, Amoco, ARCO (LyondeU), and Phillips. Some of the features of these processes are discussed herein. 

Shock, R.A.W., 1983. Encrustation of crystallizers. Journal of separation process technology, 4, 1-13. 

It should therefore not be surprising that for relatively small-scale operations involving solids handling within the fine and intermediate chemicals industry, batch operation is preferred. Similarly, continuous processes that involve precipitation or crystallization, a common unit operation in fine chemicals, are rare. Small-scale examples are known, for instance, a continuous crystallization process was used by Bristol-Myres Squibb in order to improve dissolution rates and bioavailability of the product [12]. The above does indicate that not all process or parts thereof are suited for conversion from B2C, given the current technology. 

Many different zeolite structures are already known, but there is permanent need for new or improved ones to satisfy novel and specific industrial and technological applications. To successfully accomplish this task, a deeper understanding of the zeolite crystallization process is certainly needed. One of the important parts in that study is the structural investigations of their amorphous aluminosilicate precursors (gels). 

The non-random two-liquid segment activity coefficient model is a recent development of Chen and Song at Aspen Technology, Inc., [1], It is derived from the polymer NRTL model of Chen [26], which in turn is developed from the original NRTL model of Renon and Prausznitz [27]. The NRTL-SAC model is proposed in support of pharmaceutical and fine chemicals process and product design, for the qualitative tasks of solvent selection and the first approximation of phase equilibrium behavior in vapour liquid and liquid systems, where dissolved or solid phase pharmaceutical solutes are present. The application of NRTL-SAC is demonstrated here with a case study on the active pharmaceutical intermediate Cimetidine, and the design of a suitable crystallization process. 

Shekunov BY, York P (2000) Crystallization processes in pharmaceutical technology and drug delivery design. J Cryst Growth 211 122-136... 

T0297 EPOC Water, Inc., Microfiltration Technology (EXXFLOW and EXXPRESS) T0319 FTC Acquisition Corporation, DirCon Freeze Crystallization Process T0359 GTS Duratek, DuraMelter... 

The DirCon freeze crystallization process is a technology that can be used to purify aqueous waste streams and concentrate liquid waste by the freezing and subsequent melting of the liquid. This technology is a type of direct-contact secondary-refrigerant freeze crystallization and operates on the principle that when water freezes, the crystal structure that forms naturally exudes contaminants from its matrix. The terms freeze crystallization and freeze concentration are often used interchangeably. 

Yu LX, Lionberger RA, Rawa AS, Wu D Costa R, Hussain AS. Applications of process analytical technology to crystallization processes. Center Drug Eval Res FDA 2003 8. 

The Phillips process is a two-stage crystallization process that uses a pulsed column in the second stage to purify the crystals (79,80). In the pulsed column, countercurrent contact of the high purity PX liquid with cold crystals results in displacement of impurities. In the first stage, a rotary filter is used. In both stages, scraped surface chillers are used. This process was commercialized in 1957, but no plants in operation as of 1996 use this technology. 

Huang, C Pan, J.R., Lee, M. and Yen, S. (2007) Treatment of high-level arsenic-containing wastewater by fluidized bed crystallization process. Journal of Chemical Technology and Biotechnology, 82(3), 289-94. 

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