1. SINGLE EFFECT EVAPORATORS

2. PROCESS DESCRIPTION
• OBJECTIVES
• CONCENTRATE SOLUTE
• RECOVER SOLVENT
• FORM CRYSTALS
• MECHANISM
• HEAT EXCHANGE WITH
PHASE CHANGE
• BATCH OR CONTINUOUS

3. DESIGN FACTORS
• SOLUTION FLUID VISCOSITY
• HEAT TRANSFER COEFFICIENTS
• PRESSURE DROPS
• SOLUTE SOLUBILITY
• SUPERSATURATED CONDITION
• MATERIALS (BIO-MATERIALS)
MAY BE HEAT SENSITIVE
• DEGRADATION TEMPERATURE
• ELEVATED PRESSURE
• BOILING POINT ELEVATION

4. EVAPORATION DESIGN
FACTORS
• HIGH TEMPERATURE
REACTIONS
• FOAMING
• SCALING AND CORROSION

5. OTHER DESIGN FACTORS
• SPECIFIC HEAT
• HEAT OF CONCENTRATION
• FREEZING POINT VS. CONCENTRATION
• GAS LIBERATION
• TOXICITY
• EXPLOSION HAZARDS
• NEED FOR STERILITY

6. EVAPORATION EQUIPMENT

7. EVAPORATION EQUIPMENT
• FORCED CIRCULATION AND RECOMPRESSION UNITS
http://www.niroinc.com/html/evaporator/esys.html

8. EVAPORATOR EQUIPMENT
• PLATE & FRAME - CRYSTALLIZERS

9. THIN FILM EVAPORATORS
• USED FOR
VISCOUS AND
THERMALLY
SENSITIVE
MEDIA

10. EVAPORATOR CONFIGURATION
• SINGLE STAGE EVAPORATORS
• HEAT TRANSFER
q = UA(T s−T1 ) (8.2 − 1)

11. 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

12. 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)

13. BOILING POINT
•
ELEVATION
DÜRING’S RULE –
SOLUTION BOILING
POINT IS LINEARLY
RELATED TO PURE
WATER NBPt AT PSYS