Transcript KMH 108 INTRODUCTION TO CHEMICAL ENGINEERING

DEPARTMENT OF CHEMICAL ENGINEERING
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EVAPORATORS
DAIRY INDUSTRY APPLICATION
Asist. Prof. Levent AKYALÇIN
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Evaporation
• Evaporation is the
conversion of a liquid to
a vapor.
• Evaporation is the
removal of volatile
solvent from a solution
or relatively dilutes slurry
by vaporizing the
solvent.
Evaporators are used for
this process.
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Evaporators
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Evaporators are used to separate materials
based on differences in their boiling
temperatures.
Its purpose is to concentrate nonvolatile
solutes such as organic compounds,
inorganic salts, acids or bases. Typical
solutes include phosphoric acid, caustic
soda, sodium chloride, sodium sulfate,
gelatin, syrups and urea.
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Types of Evaporators
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Long-Tube Vertical Evaporators
Short-Tube (Calandria) Vertical
Evaporators
Horizontal-Tube Evaporators
Forced Circulation Evaporators
Agitated, Thin Film Evaporators
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LONG-TUBE VERTICAL (LTV)
EVAPORATORS
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These types of evaporators are used more than
all other types combined for evaporation
because of
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low cost per unit capacity
simplicity of construction
heat transfer performance
The LTV-type evaporator cannot handle
crystallizing solutions but excellent for foaming
solution.
There are two main types of LTV evaporators:
a)
b)
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Climbing (Rising) film evaporators
Falling film evaporators
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Climbing (Rising) Film Evaporators
• LTV rising-film evaporator is
used primarily to concentrate
non-salting liquors.
• Climbing film evaporators are
used mainly in the paper
industry, food industry to
condense milk.
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Double-Effect, LTV Climbing (Rising) Film Evaporator
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Falling Film Evaporators
• LTV falling film evaporator
can be used to concentrate
the non-salting liquids and
more viscous liquors.
• Principal applications have
been for citrus juices. They
are also used to
concentrate heat-sensitive
materials and corrosive
solutions.
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Two, 4-Stage, Mechanical Recompression, Falling-Film
Evaporators
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SHORT-TUBE (CALANDRIA)
VERTICAL EVAPORATORS (STV)
• The short tube evaporators
were the first developed
commercially and still represent
probably the largest number of
unit in operation.
• Used in sugar factory.
• Used for noncorrosive materials.
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Advantages
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Inexpensive
Efficient heat transfer at high temperature
Easy to descale
Disadvantages
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Poor heat transfer at low temperature
differences or with viscous liquids
Require a great deal of floor space
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HORIZONTAL TUBE EVAPORATORS
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Horizontal tube evaporators use a tube and
spray method of heat transfer.
The tubes are arranged so as to maximize
the heat transfer area between the steam
and the liquor.
Symbols:
 C = condensate
 F = feed
 N = noncondensibles’ vent
 P = product or concentrate
 S = steam
 V = vapor
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The major use is for making distilled water
for boiler feed. Horizontal tube
evaporators are used in the
pharmaceutical industry, pulp and paper
industry.
They are relatively low cost. They have
very low headroom. Horizontal tube
evaporators are not suitable for salting or
scaling liquids, and they have smaller
capacity than other evaporators.
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Horizontal Tube Evaporator
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FORCED CIRCILATION
EVAPORATORS
• The liquor in a forced-circulation evaporator
is pumped through the tubes to minimize
tube scaling or salting when precipitates are
formed during evaporation.
• Submerged-tube type is the most common
type forced circulation evaporator.
• Forced circulation evaporators are used in the
mining industry, and also they are used to
evaporate corrosive or highly viscous
solutions.
• Forced circulation evaporators are efficient
the transfers heat from steam to liquid,
continuous liquid flow, low amount of salting,
scaling and fouling. They are expensive and
need power for circulating pump.
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Forced Circulation Evaporator
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AGITATED THIN (WIPED-FILM) FILM
EVAPORATORS
Agitated film evaporators use mechanical to promote heat transfer.
They employ a single large diameter straight or tapered tube as the
heating surface, in which a set of the blades is rotated. The cost of
these evaporators is very high and the capacity relatively low.
 These evaporators are used highly viscous liquids or liquids requiring
very low residence times. These evaporators exhibit poor heat transfer
performance on low viscosity fluids.
 Their maintenance are difficult because of internal moving parts.
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Symbols:
 C = condensate
 F = feed
 N = noncondensibles’ vent
 P = product or concentrate
 S = steam
 V = vapor
Agitated Thin Film Evaporator
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Evaporated and Condensed Milk
Evaporated milk is made by reducing the water content by
using an evaporator. Condensed milk is processed similarly to
evaporated milk, but sugar is added to improve flavor and
increase storage life. The following processing steps are
usually involved:
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Milk is received an cooled.
Milk is sampled and evaluated for bacterial count, sediment, acidity, alcohol,
appearance, flavor, and odor.
Milk is clarified or filtered.
Milk is stored and fat standardized to solids not fat.
Milk is preheated and held.
Water is removed by evaporation.
Product is homogenized.
Product is cooled. (If making condensed milk, homogenized precedes evaporation
and sugar is added immediately after condensation.)
Product is restandardized
Product is placed in cans which are sealed.
Leaking cans are rejected.
Product in cans is heated, sterilized, and cooled.
Cans are cased.
Cans with product are stored.
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EVAPORATION İN DAIRY INDUSTRY
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Definition of evaporation in application of
dairy industry is removing moisture from
milk under a vacuum with boiling.
A type of evaporator used in milk industry
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EVAPORATOR TYPES USED IN THE
MILK INDUSTRY
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Many evaporators are produced in various
designs.
Single-or multiple-effect evaporators are
used. Double- and triple- effect evaporators
are most common.
Appropriate types of evaporators that can be
used in the milk industry are as follows;
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Falling Film Evaporators
Circulation/Vertical Evaporators
Horizontal Tubes Evaporators
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Some Photos of Evaporators Which are used in
Bozüyük Milk Industry
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Number
Name
23378324080
BERDA ALTUN
24395379350
EMRAH ÖREK
37750471576
CANSU KAYAALP
55129570408
SEVİM ÖZGÜL
60907135168
PINAR ERKUŞ
25
THANKS…
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