Evoparation

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Evoparation

  1. 1. EVAPORATION HEAT TRANSFER COEFFICIENTS AND SINGLE EFFECT EVAPORATORS By T.Shivakumar B.PharmacyShiva.pharmacist@gmail.com
  2. 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. 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. 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. 5. OTHER DESIGN FACTORS• SPECIFIC HEAT• HEAT OF CONCENTRATION• FREEZING POINT VS. CONCENTRATION• GAS LIBERATION• TOXICITY• EXPLOSION HAZARDS• NEED FOR STERILITY
  6. 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. 7. EVAPORATION EQUIPMENT• SUMMARIZED IN FIGURE 8.2-1 http://www.niroinc.com/html/evaporator/esys.html
  8. 8. EVAPORATION EQUIPMENT• FORCED CIRCULATION AND RECOMPRESSION UNITS http://www.niroinc.com/html/evaporator/esys.html
  9. 9. EVAPORATOR EQUIPMENT• PLATE & FRAME - CRYSTALLIZERS http://www.niroinc.com/html/evaporator/esys.html
  10. 10. OSLO TYPE CRYSTALLIZERS http://www.niroinc.com/html/evaporator/esys.html
  11. 11. OTHER CRYSTALLIZERS http://www.niroinc.com/html/evaporator/esys.html
  12. 12. THIN FILM EVAPORATORS• USED FOR VISCOUS AND THERMALLY SENSITIVE MEDIAhttp://www.artisanind.com/documents/pa_lecithin.pdf
  13. 13. INTEGRATED PLANThttp://www.niroinc.com/html/evaporator/flash-ppt/VMPfcopy1.html
  14. 14. EVAPORATOR CONFIGURATION• SINGLE STAGE EVAPORATORS• HEAT TRANSFER q = UA(T s−T1 ) (8.2 − 1)
  15. 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. 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. 17. PARALLEL FEED• SOLAR EVAPORATION SYSTEM http://www.rio5.com/proceedings/Solar/da_Silva_et_al_201-206.pdf
  18. 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. 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. 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. 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. 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. 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. 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. 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. 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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