evaporator from net
Post on 09-Apr-2018
218 Views
Preview:
TRANSCRIPT
-
8/7/2019 Evaporator from net
1/30
Equipment used in evaporation, the process ofboiling a liquid in order to reduce its volume
NeedReduces transportation cost
Storage costs
Prepare for the next Unit operation drying,
crystallisation etc.Reduces deteriorative chemical reactions
Better microbiological stability
Recovery of solvent
-
8/7/2019 Evaporator from net
2/30
Driving force:Temperature difference in between steam chest
temperature and product temperature.
Result :
Volatile solvent is removed from the feed.
Solution (volatile solvent + non volatile solute)
Concentrate (Higher solute Conc.)
-
8/7/2019 Evaporator from net
3/30
Concentration of milk to produce condensedmilk
Concentration of juices
Concentration of NaOH, NaCl from aqueoussolutions to produce salt.
Ether recovery from fat extraction
-
8/7/2019 Evaporator from net
4/30
Heat-exchanger
Vacuum
Vapour separator Condenser
-
8/7/2019 Evaporator from net
5/30
Vapor out
Feed in
Steam in (Saturated
vapor)
Product out
Condensate out(Saturated Liquid)
Vapor
Separator
Heat Exchanger
Vaccum for non
condensable
Condensor unit
Coolant In
Coolant out
-
8/7/2019 Evaporator from net
6/30
Batch Pan
Rising Film
Falling Film
Multiple Effect Evaporators
-
8/7/2019 Evaporator from net
7/30
Conc of solute in feed
Conc of solute in product/concentrate
Pressure and Temp. of the system
Depends on temperature sensitivity of material.
Boiling point elevation
-
8/7/2019 Evaporator from net
8/30
Steam pressure and temperature
Material of construction
Foaming
Low heat transfer rate
Entrainment loss
-
8/7/2019 Evaporator from net
9/30
A coefficient which indicates the amount ofheat flow that is exchanged across a unit areaof a medium or system in a unit amount of
time with a unit of temperature differencebetween the boundary of the system.
S.I. unit W m-2 K-1.
-
8/7/2019 Evaporator from net
10/30
In cases of combined heat transfer for a heat
exchanger, there are two values for h.
Convective heat transfer coefficient for thefluid film inside the tubes
Convective heat transfer coefficient forthe fluid film outside the tubes.
The thermal conductivity (k) and thickness(Dx) of the tube wall must also be accountedfor.
So an additional term (Uo), called the overallheat transfer coefficient, must be used instead.
-
8/7/2019 Evaporator from net
11/30
-
8/7/2019 Evaporator from net
12/30
Feed water Vaporised
tank feed water
Tank Volume out to
0.92 litre/cm atmosphere
Overflow
to drain Water
main
Steam in
Constantlevel Sight
device glass
Steam
trap
Condensate
out
Condensate
tank
Tank Volume
1.31 litre/cm
-
8/7/2019 Evaporator from net
13/30
-
8/7/2019 Evaporator from net
14/30
-
8/7/2019 Evaporator from net
15/30
-
8/7/2019 Evaporator from net
16/30
Function
Discharge condensate, air and other incondensablegases from a steam system while not permitting the
escape of live steam
-
8/7/2019 Evaporator from net
17/30
-
8/7/2019 Evaporator from net
18/30
Reduces the
ferocity of
discharge andsound. Sound
levels can be
reduced by up to
80%.
-
8/7/2019 Evaporator from net
19/30
-
8/7/2019 Evaporator from net
20/30
-
8/7/2019 Evaporator from net
21/30
Vapor Out
mvhv
Steam in
mshs
Condensate out
mchc
Water in mwhw
QQEE
QQLL
-
8/7/2019 Evaporator from net
22/30
Calculate U, overall heat transfer coefficient forthe evaporator
Perform a mass balance and energy balance
Calculate discrepancy
-
8/7/2019 Evaporator from net
23/30
Feed Side:m (kg/s)
m (feed in) = m(Vapor)
Steam Side
m (steam)= m
(condensatecollected) + m (flash)
-
8/7/2019 Evaporator from net
24/30
The amount of flash steam produced during thepressure reduction can be expressed as:
w = (Hil - Hfl) / Hfewhere
w = ratio of flash steam generated (kg flash steam/ kg condensate)
Hil = initial liquid enthalpy (kJ/kg)
Hfl = final liquid enthalpy (kJ/kg) Hfe = enthalpy of evaporation (kJ/kg)
-
8/7/2019 Evaporator from net
25/30
H (kJ/kg)
Energy from the steam to the water QE
The Heat Loss from the vessel to the room, QL
Amount of heat in condensing steam QS
QS = QE + QL
-
8/7/2019 Evaporator from net
26/30
QS and QE
Mass Flow rate- condensate, feed waterT,P will give H Specific Enthalpy
Q = mH QL
Surface area
Surface temperature
QL =hA T QE = UA T
-
8/7/2019 Evaporator from net
27/30
Further Reference
Transport Processes and Separation processprinciple by:
Christie. J. Geankoplis
Animations on evaporator visit:
www.rpaulsingh.com and click animations thenevaporator
-
8/7/2019 Evaporator from net
28/30
-
8/7/2019 Evaporator from net
29/30
Water is boiled in a sequence of vessels, eachheld at a lower pressure than the last.
Because the boiling point of water decreases aspressure decreases, the vapor boiled off in onevessel can be used to heat the next
Generally the first vessel (at the highestpressure) requires an external source of heat
-
8/7/2019 Evaporator from net
30/30
top related