single effect evaporators

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