single effect evaporators
TRANSCRIPT
SINGLE EFFECT EVAPORATORS
PROCESS DESCRIPTION
• OBJECTIVES• CONCENTRATE SOLUTE• RECOVER SOLVENT• FORM CRYSTALS
• MECHANISM• HEAT EXCHANGE WITH
PHASE CHANGE• BATCH OR CONTINUOUS
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
EVAPORATION DESIGN FACTORS
• HIGH TEMPERATURE REACTIONS
• FOAMING
• SCALING AND CORROSION
OTHER DESIGN FACTORS
• SPECIFIC HEAT• HEAT OF CONCENTRATION• FREEZING POINT VS. CONCENTRATION• GAS LIBERATION• TOXICITY• EXPLOSION HAZARDS• NEED FOR STERILITY
EVAPORATION EQUIPMENT
EVAPORATION EQUIPMENT• FORCED CIRCULATION AND RECOMPRESSION UNITS
http://www.niroinc.com/html/evaporator/esys.html
EVAPORATOR EQUIPMENT
• PLATE & FRAME - CRYSTALLIZERS
THIN FILM EVAPORATORS
• USED FOR VISCOUS AND THERMALLY SENSITIVE MEDIA
EVAPORATOR CONFIGURATION
• SINGLE STAGE EVAPORATORS• HEAT TRANSFER
)12.8()( 1 TTUAq s
SINGLE STAGE MODELS
• MASS AND ENERGY BALANCES
STEAMCONDENSATE
FEED SOLUTIONPRODUCT VAPOR
PRODUCT LIQUID
F, TF,xF,hF V,TBP,yV,HV
L, TBP,xL,hL
S,TS,HSC,TC,hC
CSVLF
MASS & ENERGY BALANCES
• COMPONENT MASS BALANCE
• SYSTEM HEAT BALANCE
VAPORINSOLUTENOLxFx LF
)84.8(
)74.8(
)64.8(
Sq
HVHLhSFh
ShVHLhSHFh
vapVLF
SVLSF
BOILING POINT ELEVATION
• DÜRING’S RULE – SOLUTION BOILING POINT IS LINEARLY RELATED TO PURE WATER NBPt AT PSYS