General Design and Operational Considerations

In continuous evaporating or cooling crystallizers there are five main functional steps that must be accommodated in the design  

Mother liquor is circulated, with or without crystal contem, through a heat exchanger where heat is added or removed from the system. (Adiabsffic vacuum cooling crystallizers do not require this step.) 

Supersaturation is generated by flashing vapor, by direct or indirect cooling, Ity evaporative concentration, or by salting out. 

Supersaturation is dischaiged by growth on crystals suspended in the liquor and, to a varying extent, generation of new crystals or nuclei. 

The product crystals and residue liquor (mother liquor) are discharged either together or as separate streams. 

The natural shape or habit of a crystal obtained in the medium from which it is crystallized is of minus) importance in designing an industrial-scale ciystallizer. Crystal habit is also of extrema interest to crystallization thcorisia, Many anicles have been writtno describing variables ther affect natural habit, and) 

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General Considerations The following general design and operational considerations for avoiding unintended chemical reactions are summarized from a CCPS Safety Alert (2001) ... 

Some details of the microstructures and physical, chemical and surface properties of inorganic membranes (particularly the porous ones) have been described in Cluster 4. In this chapter, those properties related to membrane performance during and between applications and general features of commercial membrane elements, modules and systems will be discussed along with application characteristics and design and operating considerations. 

Additional considerations in the design and operation of a remote hydrogen plasma system include the following (1) convective heat transfer between the downstream gas and the specimen can introduce a significant difference between the heater temperature and the specimen surface temperature (this effect is generally not as severe as for direct immersion in... 

General Considerations The following should be taken into account whenever designing or operating a chemical process that involves intended chemical reactions (Hendershot 2002). CCPS (1999) also details many key issues and process safety practices to consider that are oriented toward the design and operation of batch reaction systems. 

The mitigation of fouling in combustion equipment therefore, is of primary concern for designers and operators with special reference to the fuel. The problem of fouling and slagging is an important consideration in the choice of combustion process and for convenience the various fuels will be discussed separately as they generally generate different problems. 

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