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Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
Evoparation
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Evoparation

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  • 1. EVAPORATION HEAT TRANSFER COEFFICIENTS AND SINGLE EFFECT EVAPORATORS By T.Shivakumar B.PharmacyShiva.pharmacist@gmail.com
  • 2. PROCESS DESCRIPTION• OBJECTIVES – CONCENTRATE SOLUTE – RECOVER SOLVENT – FORM CRYSTALS• MECHANISM – HEAT EXCHANGE WITH PHASE CHANGE – BATCH OR CONTINUOUS http://www.niroinc.com/html/evaporator/rising_film_evaporators.html
  • 3. DESIGN FACTORS• SOLUTION FLUID VISCOSITY – HEAT TRANSFER COEFFICIENTS – PRESSURE DROPS• SOLUTE SOLUBILITY – SUPERSATURATED CONDITION• MATERIALS (BIO-MATERIALS) http://www.aai- MAY BE HEAT SENSITIVE csi.com/images/evaporator. jpg – DEGRADATION TEMPERATURE • ELEVATED PRESSURE • BOILING POINT ELEVATION
  • 4. EVAPORATION DESIGN FACTORS• HIGH TEMPERATURE REACTIONS• FOAMING• SCALING AND CORROSION http://www.aquasant- mt.com/Foam.159.0.html?&L=1 http://www.champ- tech.com/images/products/p ipe.jpg
  • 5. OTHER DESIGN FACTORS• SPECIFIC HEAT• HEAT OF CONCENTRATION• FREEZING POINT VS. CONCENTRATION• GAS LIBERATION• TOXICITY• EXPLOSION HAZARDS• NEED FOR STERILITY
  • 6. EVAPORATION COMPARED WITH DISTILLATION• SOLUTE IN EVAPORATION IS GENERALLY NON-VOLATILE, RELATIVE TO SOLVENThttp://www.novasep.com/technologies/i http://www.schoolscience.co.uk/contenmg/evaporation-graph2.gif t/4/chemistry/petroleum/knowl/images/ still.jpg
  • 7. EVAPORATION EQUIPMENT• SUMMARIZED IN FIGURE 8.2-1 http://www.niroinc.com/html/evaporator/esys.html
  • 8. EVAPORATION EQUIPMENT• FORCED CIRCULATION AND RECOMPRESSION UNITS http://www.niroinc.com/html/evaporator/esys.html
  • 9. EVAPORATOR EQUIPMENT• PLATE & FRAME - CRYSTALLIZERS http://www.niroinc.com/html/evaporator/esys.html
  • 10. OSLO TYPE CRYSTALLIZERS http://www.niroinc.com/html/evaporator/esys.html
  • 11. OTHER CRYSTALLIZERS http://www.niroinc.com/html/evaporator/esys.html
  • 12. THIN FILM EVAPORATORS• USED FOR VISCOUS AND THERMALLY SENSITIVE MEDIAhttp://www.artisanind.com/documents/pa_lecithin.pdf
  • 13. INTEGRATED PLANThttp://www.niroinc.com/html/evaporator/flash-ppt/VMPfcopy1.html
  • 14. EVAPORATOR CONFIGURATION• SINGLE STAGE EVAPORATORS• HEAT TRANSFER q = UA(T s−T1 ) (8.2 − 1)
  • 15. MULTI-EFFECT EVAPORATORS• STEAM FROM ONE EFFECT IS THE HEAT SOURCE FOR THE SECOND EFFECT http://www.nukem.de/global/downloads/englisch/Evaporation.pdf
  • 16. MULTI-EFFECT COUNTERFLOW CONFIGURATION• FIGURE 8.2-3 FEED-FOREWARD – PRESSURE IS REDUCED IN EACH STAGE – FEED & STEAM ENTER THE SAME STAGE IN THE TRAIN• FIGURE 8.2-4 – FEED-BACKWARD – PRESSURE IS INCREASED IN EACH STAGE – FEED & STEAM ENTER FROM OPPOSITE ENDS OF THE TRAIN
  • 17. PARALLEL FEED• SOLAR EVAPORATION SYSTEM http://www.rio5.com/proceedings/Solar/da_Silva_et_al_201-206.pdf
  • 18. EVAPORATOR HEAT TRANSFER• OVERALL HEAT TRANSFER COEFFICIENTS – SEE TABLE 8.3-1• NEED TO KNOW RANGE TO REVIEW QUOTED DESIGNS• NOTE THAT PLATE & FRAME CAN HAVE HIGHER COEFFICIENTS THAN SHELL & TUBE.
  • 19. CHANGE OF PHASE HEAT TRANSFER• SECTION 4.8 FOR SUMMARY OF MECHANISMS• FIGURE 4.8-1 – CONVECTION – NUCLEATE – TRANSITION – FILM http://www.scielo.br/img/revistas/jbsmse/v 27n1/25372f10.gif
  • 20. HEAT TRANSFER COEFFICIENTS• BASED ON ΔT NUCLEATE BOILING CONFIGURATION EQUATION RANGE REFERENCE HORIZONTAL q/A, kW/m2 < 16 (4.8-1) HORIZONTAL 16 < q/A, kW/m2 (4.8-2) < 240 VERTICAL q/A, kW/m2 < 3 (4.8-3) VERTICAL 3 < q/A, kW/m2 < (4.8-4) 63 FORCED Psys = kPa (4.8-5) CONVECTION IN TUBES FILM BOILING HORIZONTAL (4.8-6) TUBE
  • 21. OTHER CORRELATIONS• FOR EACH CONFIGURATION• PERRY’S PAGE 5-22• HANDBOOK – http://www.wlv.com/product s/databook/ch5_3.pdf• CONVECTIVE BOILING IN COILED TUBES – http://www.graham- mfg.com/downloads/12.pdf• BASED ON SURFACE – http://www.energy.kth.se/in dex.asp? pnr=10&ID=125&lang=0
  • 22. SINGLE STAGE MODELS• MASS AND ENERGY BALANCES PRODUCT VAPOR FEED SOLUTION F, TF,xF,hF V,TBP,yV,HV L, TBP,xL,hL CONDENSATE STEAM C,TC,hC PRODUCT LIQUID S,TS,HS F = L +V S = C
  • 23. MASS & ENERGY BALANCES• COMPONENT MASS BALANCE xF F = xL L NO SOLUTE IN VAPOR• SYSTEM HEAT BALANCE Fh F +SH S = LhL +VH V + Sh S (8.4 − 6) Fh F +Sλ = LhL +VH V λ = ∆H vap (8.4 − 7) q = Sλ (8.4 − 8)
  • 24. OTHER DESIGN FACTORS• LOWER EVAPORATION PRESSURE – WILL INCREASE EFFECTIVE ΔT – LOWER EVAPORATOR AREA – INCREASED SOLVENT CONDENSER AREA – HIGHER VELOCITIES MIST ELIMINATION• BOILING POINT ELEVATION – REDUCES EFFECTIVE ΔT WITH INCREASING CONCENTRATION
  • 25. BOILING POINT ELEVATION• DÜRING’S RULE – SOLUTION BOILING POINT IS LINEARLY RELATED TO PURE WATER NBPt AT PSYS• FIGURE 8.4-2http://www.nzifst.org.nz/unitoperations/unopsassets/fig8-3.gif
  • 26. ENTHALPY- CONCENTRATION• HEAT OF MIXING EFFECTS• NON-IDEAL Dharmendira Kumar, M.; Ashok Kumar, P.; Rajendran, M., Salt Effect on the Enthalpy of Mixing of 1,4-Dioxane + Acetic Acid at 303.15 K , J. Chem. Eng. Data; (Article); 2003; 48(6); 1422-1424.

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