7/29/2019 Evaporator Presentation
1/63
Nestle Milkpak Ltd. SKP 2004
M.Arshad
Training onPowder Manufacturing
Evap & Egron Department
7/29/2019 Evaporator Presentation
2/63
Nestle Milkpak Ltd. SKP 2004
M.Arshad
Evaporator
7/29/2019 Evaporator Presentation
3/63
Nestle Milkpak Ltd. SKP 2004
M.Arshad
Introduction
7/29/2019 Evaporator Presentation
4/63
Nestle Milkpak Ltd. SKP 2004
M.Arshad
Contents:
Milk evaporation statistics
What is evaporation and why do it
Characteristics of evaporation Evaporator types
Falling film principle
Falling Film Evaporator elements
7/29/2019 Evaporator Presentation
5/63Nestle Milkpak Ltd. SKP 2004 M.Arshad
Global Statistics on Milk (2004)
World fresh milk
production:
577 Mio Ton Nestle share:
12.1 Mio Ton
Nestle
2.1%
Others
97.9%
Nestle
Others
7/29/2019 Evaporator Presentation
6/63Nestle Milkpak Ltd. SKP 2004 M.Arshad
Statistics on Milk Processed withEvaporators (2004)
Fresh milk processed atNestl: 12.1 Mio Ton
Milk processed in
Evaporators: 8.0 Mio Ton
(66% of Nestl total milk)
SCM9%
Others
6%
UHT + steril
7%
Chocolate
7%
IceCream
5%Milk powders
50%
Evap
7%
White refr.
9%
7/29/2019 Evaporator Presentation
7/63Nestle Milkpak Ltd. SKP 2004 M.Arshad
What is Evaporation?
Change from liquid phase to the vapour phase
For example,Boiling water
Heat
Water
Vapour
7/29/2019 Evaporator Presentation
8/63Nestle Milkpak Ltd. SKP 2004 M.Arshad
What is Condensation
Change from vapour phase to the liquid phase
For example,
Condensing steam
Heat
Condensate
Vapour
?
7/29/2019 Evaporator Presentation
9/63Nestle Milkpak Ltd. SKP 2004 M.Arshad
Evaporation by means of steam
Heat transfer because of
temperature difference
Condensate
Steam
Milk
Vapour
Steam at
Higher temperature
Vapour at
Lower temperature
Surface to
exchange heat(indirect)
7/29/2019 Evaporator Presentation
10/63Nestle Milkpak Ltd. SKP 2004 M.Arshad
So during evaporation:
* Solids do not evaporate ,hence
* Concentration of solids in liquid phase increases
100 kg Milk, 12 % TS:
12 kg solids88 kg water Evaporator
76 kg vapour
24 kg Milk, 50 % TS:
12 kg solids12 kg water
7/29/2019 Evaporator Presentation
11/63Nestle Milkpak Ltd. SKP 2004 M.Arshad
Evaporation / ConcentrationMethods
Evaporator(indirect) - liquid in - liquid out
Spray Dryer(direct) - liquid in - solid out
Roller Dryer(indirect) - liquid in - solid out
7/29/2019 Evaporator Presentation
12/63Nestle Milkpak Ltd. SKP 2004 M.Arshad
Why Evaporate/concentrate
Volume ReductionFor example: to reduce transport volume of Milk from source to factory.
PreservationFor example: Milk Powder: suspended bacteriological activity due to lack of
water.
?
ConvenienceFor example: - Evaporated Milk.
- Instant Coffee/ Tea whitener
7/29/2019 Evaporator Presentation
13/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Evaporator Types
The Old Vacuum Pan
Recirculation Evaporators
Climbing Film Evaporators
Falling Film evaporators
Plate Evaporators
7/29/2019 Evaporator Presentation
14/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Energy Use =
1.25 KW/Kg H2O
Energy Use =
0.07 KW/Kg H2O
SPRAYDRYER
Fresh milk:
1000 kg
Energy Use
= 4.2 KW/Kg H2O
Energy Use
= 4.2 KW/Kg H2O
Evaporates
3.1 kg of water
Evaporates
121 kg of water
Evaporates
747 kg of water
Why are Evaporatorsthe preferredconcentration
equipment(example IMP)
time: 12-15 min Time: 1/4-1 min Time: 5-15 min
12.5% 97.3%95%49.5%Evaporator Spray dryer Afterdryer
7/29/2019 Evaporator Presentation
15/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Evaporator Process ATSKP
Std silo
Condenser
Pre-heating
Thermo compressorPasteuriser
DSI
Back pressure
Evaporation in
1st Effect
2nd Effect
4
th
Effect-A&B3rd Effect-A&B
Ex-Evap
Homo tank
Buffer tank(if need)
7/29/2019 Evaporator Presentation
16/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
BRAN & LUEBBEMETERING SYSTEM
Flowsheet of SKP evap.
7/29/2019 Evaporator Presentation
17/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Evaporator Process
Standardized Silo Plan
Batch card
Quality
MSA/DPSA
7/29/2019 Evaporator Presentation
18/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Evaporator Process
CondenserSTD Milk Temp
Cooling tower
Preheating of milk
Vapour condensation
7/29/2019 Evaporator Presentation
19/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Condenser
Vapoursarecondensedby
means of Cooling Water
This creates a SUCTION EFFECT
i.e. VACUUM
In
The BIG volume
0ccupied by the
VapoursIs suddenly
reduced to
To a very small
volume of liquid
Out
7/29/2019 Evaporator Presentation
20/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Condensate
Condensate from Pasteurizer: -->Boiler House
Condensate from 1st effect: -
conductivity measurement, if OK
--> to Boiler House
Condensate from other effects andCondenser:
--> Other uses
Pure-Condensate
Condensate-
from Product
Vapour
Condenser
Pasteurizer
Condensate from Steam-recompressedvapours
Steam
Steam
7/29/2019 Evaporator Presentation
21/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Pre-Heaters
Product IN
Pre-Heater C
Pre-Heater 1
Pre-heat Product to ~70 C
Thermal EconomyEnergy has already worked
upstream Gentle heating
Low T
Heating media (vapours) at the rightT readily available
7/29/2019 Evaporator Presentation
22/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Evaporator Process
Balance TankBalance tank is a feeding source of Evaporator in
this we volume makeup
Buffer milk & wet rework
Th C
7/29/2019 Evaporator Presentation
23/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Thermo-Compressor
Vapour Pump H P Driving Steam
recompresses and mixes
with the Sucked Vapour
Simple, no moving parts
Robust (not much to go wrong) Small Unit, for Large Volumes.
To Next Effect-or
To Condenser
Vapour, mixed
Compressed
with Steam
Driving Steam
Sucked Vapours
Heating Side
Fed to
of #1 Effect at
higher T
7/29/2019 Evaporator Presentation
24/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Msteam
Psteam
Msuck
Mdisch
Psuck
Pdisch
1 2 3 4 5
1) Head
2) Steam Nozzle
3) Converging Section
4) Throat
5) Diverging Section
Thermocompressor Nozzle
7/29/2019 Evaporator Presentation
25/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Pasteuriser
Pasteuriser
Heats Product, from ~70 C to ~ 85 C Heating time is Critical
long time = Coil
short time =PHE
= Straight Tube Running time > = 20h
7/29/2019 Evaporator Presentation
26/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
DSI
7/29/2019 Evaporator Presentation
27/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
DSIDirect Steam Injection
Short Time Heat Treatment
Heat Productfrom 85 C to say 108C
Followed by Holding Tube
-Holding time - 5 to 10 Sec
-Variable holding time as needed
-Watering effect ~ 4% for 20Ctemperature rise
7/29/2019 Evaporator Presentation
28/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Why Back Pressure?
Product at high T >100 C
Uniform flow
To avoid boiling
Ensures:
Correct T is reached
Correct holding time Prevents:
Premature Flashing
Back Pressure
7/29/2019 Evaporator Presentation
29/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Evaporator Process
Evaporation in1st Effect
Product Inlet Nozzle at ist effect
7/29/2019 Evaporator Presentation
30/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Product Inlet Nozzle at ist effect
Flash-Vapour
Calandria Top Cover
Product Feed-Under Pressure
And Diverter
Flow through
S.S. Nozzle
d lThe Back pressure
will depend on "l"
and "d",
calculated for a
certain flowrate
7/29/2019 Evaporator Presentation
31/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Evaporator Process
Evaporation in2nd Effect
E P
7/29/2019 Evaporator Presentation
32/63
Nestle Milkpak Ltd. SKP 2004 M.Arshad
Evaporator Process
Evaporation in
4th Effect-A&B
E t P
7/29/2019 Evaporator
