Transcript COM KEY PROD Working principle of a PHE

Sanitary Plate Heat
Exchangers
Working Principle of a
Plate Heat Exchanger
PHE - Main Components
Carrying bar
Frame plate
Pressure
plate
Plate pack
Tightening bolts
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PHE - Dismantling
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Plate Heat Exchanger
360˚ turn
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Plate Heat Exchanger
inside
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End Plate I
Channel plates
End Plate II
Plate Pack - Example Single Pass
Hot out
Cold in
Cold out
Hot in
Only 2 plates that do not transfer heat - the end plates
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Plate Pack – Example Multipass
Pass/Channel: Hot Side 2 x 4
Cold Side 2 x 4
Cold out
Cold in
Hot in
Hot out
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Applications
In the Dairy
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Milk pasteurization
Cream pasteurization
Cultured milk treatment
UHT
Cheese milk heat treatment
Ice cream mix heat treatment
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Applications
Pasteurization
IP
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Frame - purpose
• Holds the plates together
• Supports the plates (load / pressure)
• Base for connections (inlet / outlet for media)
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Frame - Types
• Industrial types (mild steel, painted):
FM, FG, FD
Only used for utility (water heaters/coolers)
• Hygienic types (stainless steel):
Base, FMC, FHC, FRM, FRH, FRD, RM
Normally used in the Food industry
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Frame - > M15 and FrontLine™
Carrying bar
• Unique 5-point alignment system
– Provides exact positioning
of the plates horizontally
and vertically
– Ensures good sealing
throughout the plate pack
Plate
Guiding
bar
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FrontLine™
• Solid stainless steel frame and
pressure plates
• Cleaner since there is no risk of
cracks in cladding allowing dirt
and bacteria build-up
• More durable since there is no
internal mild steel structure that
can corrode
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FrontLine™
• Stainless steel bolts with ball
bearing washers
• Reduces service time
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FrontLine™
• Bolt-in corners at connection
plates
• Easy to modify for new duties
and applications
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FrontLine™
Other Options
• 3A polished fittings
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Connections in Titanium
High legs
Protection sheets
Stainless steel bolt covers
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Hygienic Frame - Connection Plate
• Connection plates are used in multi–section
units when one or more fluid must enter or
leave the PHE at a location other than the
frame or pressure plate.
• Available as standard for types with hygienic
frames – Front 10, Front 8, Front 6, Clip 3,
M15, M10, M6, TL10B
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Plates - Purpose
• Create channels for the liquids (corrugation).
• Create turbulence for the flow
• Provides the heat transfer from one media to the other media.
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The Channel Plate Construction
• Plate pattern (L , M and H )
• Pressing depth
• Clip and M plates
B plates
• Physical length and width of plate
• Increase the number of passes
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Plates
Inlet / outlet Media 2
Inlet / outlet Media 1
Distribution area
Fully supported gasket
groove
Heat transfer area
Distribution area
Inlet / outlet Media 1
Inlet / outlet Media 2
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Plate - Distribution Area
• Chocolate pattern
– Distributes flow evenly over the plate
– Same P for distance A and B
– Uses a minimum of P for distribution
A
– Gives more P for efficient heat transfer
– Avoids dead spots in the far corner
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Corner Guidance
• First alignment made by the
carrying & guiding bar
• Corner guidance locks the
plates in position and finetunes the alignment
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Plate - Corrugation and Channels
• We have two plate corrugations (L and H)
• These form three different channels (L, M and H)
H: High theta
L: Low theta
L + L = L channels
L + H = M channels
H + H = H channels
• We choose between L, M and H channels
• Tailor-made for the specific duty
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Plate - corrugation and channels
Low turbulence
& pressure drop
Medium turbulence
& pressure drop
High turbulence
& pressure drop
L + L = L channels
L + H = M channels
H + H = H channels
Advantages
Benefits
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Efficient heat transfer
High wall shear stress
Variable thermal length
Strong construction
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Increased heat recovery
Low fouling
Optimal design
Insensitive to vibration
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The Plate Corrugation has
two Functions:
Mechanical – to make the plate
rigid and provide interplate
support points.
Flow dynamic – to promote
interplate fluid turbulence for
high efficiency.
Compact
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Plate Pattern
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Herring bone
Contact points
– Mechanical Strength
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Flow pattern
– Cork screw
– High turbulence
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The Front Standard Plate
• High and Low theta plates
• Optimize the design for both
thermal and product
considerations
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The Front Standard Plate
• Deeper pressing depth
• Ability to handle small
particulates
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The Front Standard Plate
• Wide corrugations
• Longer run times at same rate
of fouling
Clip plate
Other unit
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The Front Standard Plate
• Five point alignment system
• Ensures plate and gasket are
aligned during take-up
• Reinforced for frequent
opening and closing
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The Front Standard Plate
• Long & narrow geometry
• Even flow & heat transfer
across plate surface
• Low CIP flow rates
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The Front Standard Plate
• Flow distribution area
• No “dead spots” for better
hygiene
• Promotes even flow across
plate surface
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The Front Standard Plate
• Smaller port holes, tubing
dimensions
• Lower CIP flow rates, better
hygiene
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The Front Standard Plate
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Bright annealed finish
Easier to clean
Easier to inspect
Higher corrosion resistance
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Sanitary PHE Plate Design
• Plate geometry (long & narrow)
• Port holes
• Distribution area
• Stagnant areas
• Pressing depth and corrugation
• Plate surface
Front standard plate
Other plate
•…to eliminate any risk for
infection in pasteurisers
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Plate Pack Assembly
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Channel Plate
End Plate II
(gasket against frame)
•
End plate I
(metal against frame)
• Turn Plate
• Transition Plate
• Partition Plate
• Connection Plate
End
plate I
End
plate II
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Plate Pack - Channel Plates
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Channel Plates are the heat transfer plates
They dominate the plate pack
Most frequently with 4 holes punched
Alternating A / B (turned 180 degrees)
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Plate Pack - End Plate I
• In single pass,
– Stops fluid at the end of the plate pack
– Last plate at carbon steel pressure plate
– No port holes are punched
• In multi-pass,
– Stops one fluid as it reaches the end
– Allows other to flow into the plate pack
– 2nd last plate in the plate pack
(transition plate behind it)
– Hole combination as per pass
arrangement
Normal gasket as on channel plates
•
• Usually in 0.6 mm with high-theta pattern
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Plate Pack - Turning Plate
• Used in multi-pass
• 1, 2 or 3 port can be un-punched
• Change the flow direction of one or both fluids
in between the passes
• Normal channel plate gasket
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The Construction
Number of plates depends on:
• Flow rates
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Permitted pressure drops
Temperature program
Size & design of plates
Heat recovery
Material & thickness of plates
Physical properties
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Plate Pressing
Single Step Pressing
• Plates are totally uniform
• Uniform metal-to-metal contacts points
• Stronger plates that can handle
– High pressure
– High differential pressure
– Vibrations
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Plate - Pressing Depth
• Alfa Laval has a range of pressing depths from
1.5 mm to 11 mm for optimal solution to any duty
There is no good and no bad pressing depth.
Just different ones to fit various duties
Performance
• pressure drop
• heat recovery
• compact design
• gentle product
treatment
• special products
• clogging problems
Pressing depth
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Plate - Parallel vs. Diagonal Flow
Parallel flow advantages
180º
• One plate & one gasket
– Identical plates in plate pack
– Rotated 180º to achieve both
sides
• Less spares required
• Fully supported diagonal
– Higher design pressure or
thinner plate material
• No crossing of nozzles
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Plate - Materials
• Standard materials and thicknesses
• AISI 304 (stainless steel)
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- Usually 0.4 or 0.5 mm thick
- Cheapest possible solution
AISI 316 (stainless steel) - 0.5 and 0.6 mm thick
- Some with thicker plates
(high-pressure applications)
254 SMO (high-alloy stainless steel)
- Usually in 0.6 mm to allow stock-keeping
Titanium - 0.5 and 0.6 mm thick
- Some with thicker plates
(high-pressure applications)
- Some with 0.4 mm (low-pressure applications)
Alloy C-276 (Nickel alloy)
- Usually in 0.6 mm to allow
stock-keeping
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Relative
Price
100%
115%
250%
300%
600%
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Gaskets - Purpose
• The purpose of the gaskets is to seal between the channel
plates and between plates and the frame parts (connecting
plate).
• Are the only wear part (the ageing of rubber).
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The Front Standard Plate
• Glueless gasket
• Gasket & plate work together
as a system to replace
adhesives
• Less downtime, plates can be
re-gasketed in frame
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The Front Standard Plate
• Deep gasket groove
• Protection of gasket from
elements
• Higher pressure ratings
• Ensures gasket remains on
plate during opening
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The Front Standard Plate
• Thicker Gasket
• Better resistance to thermal,
pressure and CIP cycles
• Longer gasket life
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The Front Standard Plate
• Twin gasket w/ leak detect
ports
• No chance for cross
contamination across
gaskets at port holes
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Gasket - double sealing system
Special venting ports are an integral part of the gasket design to
prevent cross contamination
If the gasket fails  Leakage is detected on the outside
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Gaskets - Standard
Nitrile:
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NBRP
= (performance) up to 110°C, Food grade
NBRB
= (base) inexpensive, lower temperature, Food grade
NBRHTF = (high temperature) Food grade
NBRFF
= upgrade of NBRHTF Food grade
Ethylene Propylene rubber:
• EPDMC = clip-on/non-glued. High temperature (non food)
• EPDMF = Food grade (FDA)
• EPDFF = upgrade of EPDMF Food grade (FDA)
(Not resistant to oil and fat)
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Gasket - Profile and Groove
Other
Alfa Laval
Profile
Higher sealing
pressure
Risk of leakage.
Groove
Full support
to gasket
Openings. Risk of
gasket blow-out.
The difference is lifetime and reliability
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Gasket - Sealing Lifetime
Product
Duty
• Gasket material
• Fastening
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– Glue or glue-free
– Type of glue
• Gasket geometry
• Gasket groove
• Alignment of plate pack
Operating temperature
Operating pressure
Media
Type of operation
continuous / cyclic
• Cleaning methods &
chemicals
• Opening frequency
Life time!
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Gasket - Sealing Lifetime
• Maximum temperature in CAS and product manual (PMP),
for example,
– NBR up to 130ºC
– EPDM up to 160ºC
 Gives about 1 year lifetime
When no chemical attack takes place
• Rule of thumb:
– 10ºC lower than max temperature  2 years lifetime
– 10ºC above the max temperature  6 months lifetime
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PMP - Pressure/Temperature
• A P/T graph can be made from data sheet information showing the
expected performance of the plate & gasket
– The design P/T should be inside the performance area
– If P/T is on the line  1 year gasket lifetime
– If P/T is outside  Cannot guarantee the performance
– If the gasket is chemically attacked  more aspects to be added
Limited by the max design pressure for the plate
Pressure (barg)
25
Gasket lifetime limited by a
combination of pressure and
temperature
20
15
Performance
area
10
5
Gasket lifetime limited by
the max temperature
0
0
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50
100
TemperatureSlide
(°C)55
150
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PMP - Pressure/Temperature
• The data is found in the data sheet
– In the gasket performance table
• T(T) = The maximum allowed operating temperature.
Above this temperature the gasket will last less than one year.
• T(P) = Recommended temperature at max pressure.
Higher pressure  More strain on the gasket 
We cannot allow the max temperature
– In the plate performance table
• P(P) = Maximum design pressure for the plate.
Above this pressure the plate will deform.
• P(T) = Recommended max operating pressure at max
operating temperature.
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Higher pressure  Softer gasket 
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We cannot allow the maxSlidepressure
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