sanitary plate heat exchangers working principle of a plate heat exchanger

Sanitary Plate Heat Exchangers

Working Principle of a Plate Heat Exchanger

© Alfa Laval Slide 2 www.alfalaval.com

PHE - Main ComponentsCarrying bar

Pressureplate

Plate packTightening bolts

Frame plate


PHE - Dismantling

Click on animation to play again


Plate Heat Exchanger

360˚ turn


Plate Heat Exchanger

inside


Cold in

Hot out

Hot in

Cold out

Plate Pack - Example Single Pass

End

Pla

te I

I

End

Pla

te I

Cha

nnel

pla

tes

Only 2 plates that do not transfer heat - the end plates


Pass/Channel: Hot Side 2 x 4

Cold Side 2 x 4

Cold in

Hot outHot in

Cold out

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Plate Pack – Example Multipass


In the Dairy

• Milk pasteurization

• Cream pasteurization

• Cultured milk treatment

• UHT

• Cheese milk heat treatment

• Ice cream mix heat treatment

Applications


Pasteurization

ApplicationsIP


Frame - purposeFrame - purpose

• Holds the plates together

• Supports the plates (load / pressure)

• Base for connections (inlet / outlet for media)


Frame - TypesFrame - 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


• Unique 5-point alignment system

– Provides exact positioning of the plates horizontally and vertically

– Ensures good sealing throughout the plate pack

Carrying bar

Guiding bar

Plate

Frame - > M15 and FrontLine™


FrontLine™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


• Stainless steel bolts with ball bearing washers

• Reduces service time



• Bolt-in corners at connection plates

• Easy to modify for new duties and applications



Other Options• 3A polished fittings

• Connections in Titanium

• High legs

• Protection sheets

• Stainless steel bolt covers



Hygienic Frame - CHygienic 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


Plates - Plates - Purpose

• Create channels for the liquids (corrugation).

• Create turbulence for the flow

• Provides the heat transfer from one media to the other media.


• 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

The Channel Plate Construction

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PlatesPlates

Distribution area

Inlet / outlet Media 1

Heat transfer area

Distribution area

Inlet / outlet Media 1Inlet / outlet Media 2

Inlet / outlet Media 2

Fully supported gasket groove


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

– Gives more P for efficient heat transfer

– Avoids dead spots in the far corner

A

B


Corner Guidance

• First alignment made by the carrying & guiding bar

• Corner guidance locks the plates in position and fine-tunes the alignment


Plate - Corrugation and Channels

L: Low theta H: High theta

• We have two plate corrugations (L and H)

L + L = L channels L + H = M channels H + H = H channels

• These form three different channels (L, M and H)

• We choose between L, M and H channels

• Tailor-made for the specific duty


Plate - corrugation and channels

Advantages

• Efficient heat transfer

• High wall shear stress

• Variable thermal length

• Strong construction

Benefits

• Increased heat recovery

• Low fouling

• Optimal design

• Insensitive to vibration

Low turbulence& pressure drop

L + L = L channels

Medium turbulence& pressure drop

L + H = M channels

High turbulence & pressure drop

H + H = H channels


The Plate Corrugation hastwo Functions:

Mechanical – to make the plate rigid and provide interplate support points.

Flow dynamic – to promote interplate fluid turbulence for high efficiency.

Compact


• Herring bone

• Contact points

– Mechanical Strength

• Flow pattern

– Cork screw

– High turbulence

Plate Pattern


The Front Standard Plate

• High and Low theta plates

• Optimize the design for both thermal and product considerations



• Deeper pressing depthDeeper pressing depth

• Ability to handle small Ability to handle small particulatesparticulates


The Front Standard Plate • Wide corrugationsWide corrugations

• Longer run times at same rate Longer run times at same rate of foulingof fouling

Other unit

Clip plate



• Five point alignment systemFive point alignment system

• Ensures plate and gasket are Ensures plate and gasket are aligned during take-upaligned during take-up

• Reinforced for frequent Reinforced for frequent opening and closingopening and closing



• Long & narrow geometryLong & narrow geometry

• Even flow & heat transfer Even flow & heat transfer across plate surfaceacross plate surface

• Low CIP flow ratesLow CIP flow rates



• Flow distribution areaFlow distribution area

• No “dead spots” for better No “dead spots” for better hygienehygiene

• Promotes even flow across Promotes even flow across plate surfaceplate surface



• Smaller port holes, tubing Smaller port holes, tubing dimensionsdimensions

• Lower CIP flow rates, better Lower CIP flow rates, better hygienehygiene



• Bright annealed finish

• Easier to clean

• Easier to inspect

• Higher corrosion resistance


Sanitary PHE Plate DesignSanitary PHE Plate DesignSanitary PHE Plate DesignSanitary PHE Plate Design

• Plate geometry (long & narrow)Plate geometry (long & narrow)

• Port holesPort holes

• Distribution areaDistribution area

• Stagnant areasStagnant areas

• Pressing depth and corrugationPressing depth and corrugation

• Plate surfacePlate surface

•……to eliminate any risk for to eliminate any risk for infection in pasteurisersinfection in pasteurisers

• Plate geometry (long & narrow)Plate geometry (long & narrow)

• Port holesPort holes

• Distribution areaDistribution area

• Stagnant areasStagnant areas

• Pressing depth and corrugationPressing depth and corrugation

• Plate surfacePlate surface

•……to eliminate any risk for to eliminate any risk for infection in pasteurisersinfection in pasteurisers

Front standard plate

Other plate


Plate Pack Assembly

• Channel Plate

• End Plate II(gasket against frame)

• End plate I(metal against frame)

• Turn Plate

• Transition Plate

• Partition Plate

• Connection PlateEnd plate II

End plate I


Plate Pack - Channel Plates

• Channel Plates are the heat transfer plates

• They dominate the plate pack

• Most frequently with 4 holes punched

• Alternating A / B (turned 180 degrees)


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

Sin

gle

pass

Exa

mpl

e,

Mul

ti pa

ss• 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


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


Number of plates depends on:

• Flow rates

• Permitted pressure drops

• Temperature program

• Size & design of plates

• Heat recovery

• Material & thickness of plates

• Physical properties

The Construction

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• Plates are totally uniform

• Uniform metal-to-metal contacts points

• Stronger plates that can handle

– High pressure

– High differential pressure

– Vibrations

Single Step Pressing

Plate Pressing


Plate - Pressing Depth

Performance

Pressing depth

• pressure drop• heat recovery• compact design

• gentle product treatment• special products• clogging problems

Thermal Product

• 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


Plate - Parallel vs. Diagonal Flow

Parallel flow advantages

• 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

180º


Plate - Materials• Standard materials and thicknesses

• AISI 304 (stainless steel)

- 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

100%

115%

250%

300%

600%

RelativePrice


Gaskets - PurposeGaskets - 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).



• Glueless gasket

• Gasket & plate work together as a system to replace adhesives

• Less downtime, plates can be re-gasketed in frame



• Deep gasket groove

• Protection of gasket from elements

• Higher pressure ratings

• Ensures gasket remains on plate during opening



• Thicker Gasket

• Better resistance to thermal, pressure and CIP cycles

• Longer gasket life



• Twin gasket w/ leak detect ports

• No chance for cross contamination across gaskets at port holes


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


Gaskets - StandardGaskets - Standard

Nitrile:

• 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)


Gasket - Profile and Groove

Profile

OtherAlfa Laval

Groove

Higher sealing pressure

Risk of leakage.

Full support to gasket

Openings. Risk of gasket blow-out.

The difference is lifetime and reliability


Gasket - Sealing Lifetime

Product

• Gasket material

• Fastening

– Glue or glue-free

– Type of glue

• Gasket geometry

• Gasket groove

• Alignment of plate pack

Duty

• Operating temperature

• Operating pressure

• Media

• Type of operation continuous / cyclic

• Cleaning methods & chemicals

• Opening frequency

Life time!


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


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

0

5

10

15

20

25

0 50 100 150

Temperature (°C)

Pre

ssu

re (

bar

g)

Performance area

Limited by the max design pressure for the plate

Gasket lifetime limited by the max temperature

Gasket lifetime limited by a combination of pressure and temperature


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.

Higher pressure Softer gasket We cannot allow the max pressure

sanitary plate heat exchangers working principle of a plate heat exchanger

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