Crystallizer Design

Crystallizer

Crystallization •

•

Crystallization is an important operation in the chemical industry as a method of purification and as a method of   prov provid idin ing g cry crysta tall llin ine e mat materia erials ls in the the desi desirred siz size rang ange A process where solid particles are formed from a homoge homogeneo neous us phase. phase.

•

It is a soli solidd-lliqu iquid sep separa aration tion proc proces esss

•

For For cont contro roll 1) 2) 3)

Yield ield of  crystal’s   crystal’s Puri Purity ty of  crystal’s   crystal’s Size izes and and shap shape es of  crystal’s   crystal’s

Theory of crystallization : 1)

2)

Supe Su perr satu saturration tion of the the so solu luti tion on a)

It can be don done by thre hree ways.

b)

Heat Heatin ing g the solut solutio ion n

c)

Cooli Cooling ng the the solu soluti tion on Salt Salting ing out

Nucleation

Thi This take akes plac place e in sev several eral steps. ps. During their random motion, the atoms/ molecules/ ions will come clos closer er to one one anot anothe herr and and form orms aggr aggreg ega ates call calle ed as CLUS CLUSTE TER RS. These clusters will combine to form an EMBRYO. In this stage only the lattic lattice e forma formatio tion n begins begins.. This   embryo’s combine to form NUCLEI. From nuclei crystals are formed 3)

Cryst Crystal al Growt Growth h

Once the crystals are formed, nuclei formation stops and crystal growt growth h begins begins..

Crystallization The crystallization process consists of two major events: Nucleation Is the step where the solute molecules dispersed in the solvent start together into clusters

The crystal growth Is the subsequen subsequentt growth growth of the nuclei nuclei that succeed succeed in achieving achieving the critical cluster size

Crystallizer Design Procedure

Crystallizer Design Procedur Procedure e The Following Step are outline for the Design of Crystallizer: 1) Choose the type of crystallizer that must meet the requirement for a)

Product Size

b)

Product Quality

c)

Process economics

2) Make a list of temp and physical properties required for calculation. 3) Make a Material balance, Heat balance and Flow sheet. 4) Decide what retention time is required to make the required product. a)

By experience

b)

From growth and nucleation rate Reference:

Cont.… 5. Size the body on the basis of controlling volume for crystal retention with due consideration for minimum cross-section required for vapor release. 6. Size the heat transfer surface. 7. Size the Vapor Pipe. 8. Select the Circulate pump. 9. Select the Agitator Ag itator..

Reference: Handbook of Industrial Crystallization

Crystallizer Designing Parameters 1) Retention time 2) Minimum Active Volume 3) Sizing 4) Height of Cylinder 5) Height of Cone

Equipment Sizing: Calculation Flow Diagram

Retention time

=

 3.67

Equipment Sizing: Calculation Flow Diagram

Retention time

=

 3.67

Minimum Active Volume

 = 

Equipment Sizing: Calculation Flow Diagram Retention time

=

 3.67

Minimum Active Volume

 = 

Sizing

 =  +    = 0.1868 +

 4

 (1.5)

Equipment Sizing: Calculation Flow Diagram Retention time

=

 3.67

Minimum Active Volume

 = 

Height of Cone

 0.1 ℎ = tan tan 55 ( − ) 2 2 

Sizing

 =  + 

Height of Cylinder

ℎ = 1.5

  = 0.1868 +

 4

 (1.5)

Mechanical Engineering Design The selected material for the crystallizer crystallizer is ( stainless steel 316) due to its high corrosion resistance. resistance. •

Shell Thickness

 =   •

 

Tori spherical Head Thickness

 = 4

 



Mechanical Engineering Design •

Cone Thickness

 =  

•

Corrosion Allowance: 2 mm







Mechanical Engineering Design •

Leg Support, Angle Type





=

=

 

[ [  −  + 6 +

 

















[ [  −  − 6 +

(−  + 6 )

(−  − 6

Mechanical Engineering Design

Figure A.5.4.5.Angle Leg Dimensions

Swirl Breaker

Pipe and Nozzle Sizing To calculate the diameters of the pipe the following equation is used. ,  = 3.9 .  .

Importance of crystallization : 1) Purification of drugs . 2) Improve bio-availability of the drug and choose the most stable form. 3) A crystalline powder is easily handled ,stable , possesses good flow properties and an attractive appearance .

Application of crystallization : 1) Puri Purifi fica cati tion on of drug drug 2) Bette Betterr proce processi ssing ng chara characte cteris ristic ticss 3) Ease ase for hand handli ling ng 4) Impro Improve ved d phys physica icall stabi stabilit lity y 5) Sustain Sustained ed release release 6) Improved Improved bioavail bioavailabil ability ity 7) Prep Prepar arat atio ion n of org organic anic and and inor inorg ganic anic API API 8) Sepa Separrat atio ion n of API API from from Ga Gale leni niccal ext xtrracts acts 9) Manu anufactu acturi rin ng of pure ure API API by high igh yiel ield