This document is an instruction manual for Plate Heat Exchangers (PHEs) manufactured by Alfa Laval. The manual covers models M3, M6, M10, TS6, T2, T5, T8, TL3, and TL6.
Function Description
A Plate Heat Exchanger (PHE) consists of a pack of corrugated metal plates with port holes for the input and output of two separate fluids. Heat transfer between the two fluids occurs through these plates. The plate pack is assembled between a frame plate and a pressure plate and compressed by tightening bolts. Each plate is fitted with a gasket that seals the channel and directs the fluids into alternate channels. The plate corrugation promotes fluid turbulence and supports the plates against differential pressure.
Multi-pass configurations can be created using turning plates, with 1, 2, or 3 unholed ports, primarily to change the flow direction of one or both fluids. Some units require a partition plate to support unholed ports in turning plates, and transition plates may be added to prevent media contact with the partition or pressure plate. Multi-pass setups are useful in processes requiring longer heating periods or slower heating of media.
Important Technical Specifications
The nameplate, typically fixed to the frame plate or pressure plate, provides crucial technical specifications including the unit type, manufacturing number, manufacturing year, and pressure vessel details in accordance with applicable codes. It also specifies the mechanical design pressures and temperatures, which must not be exceeded. The mechanical design temperature may exceed the operating temperature for which the gaskets were selected; if operating temperatures are to be exceeded, the supplier should be consulted.
Key components include:
- Frame plate: A fixed plate with port holes for piping connections, to which the carrying and guiding bars are attached.
- Carrying bar: Supports the plate pack and pressure plate.
- Plate pack: The core of the PHE where heat transfer occurs, comprising channel plates, end plates, gaskets, and sometimes transition plates. Its measurement (A dimension) is critical.
- Pressure plate: A movable plate that may have port holes for piping connections.
- Guiding bar: Aligns the channel plates, connection plates, and pressure plate at their lower end.
- Supporting column: Supports the carrying and guiding bars (not used in smaller PHE models).
- Tightening bolts: Compress the plate pack between the frame and pressure plate. Typically four or six are used for opening and closing, with remaining bolts acting as locking bolts.
- Port holes: Allow media to enter or exit the PHE, protected against corrosion by metal or rubber linings.
Connections can be fixed pipe connections (for welding, threaded, or grooved pipes), stud bolts (threaded bolts around port holes for flange connections), or squared loose flanges (special Alfa Laval flanges attached with four stud bolts).
Optional components include:
- Foot: Provides stability and secures the PHE to the foundation.
- Protection sheets: Cover the plate pack to protect against leakage of hot or aggressive fluids and to shield the hot plate pack.
- Bolt protection: Plastic tubes protecting tightening bolt threads.
- Insulation: Used when the PHE surface will be hot or cold.
- Earthing lug: For static electricity dissipation.
- Nozzle cover: Protects against particles during transportation.
- Drip tray: May be necessary depending on fluid type and installation to prevent injury or equipment damage from leaks.
Usage Features
Installation:
- Ensure all foreign objects are flushed from piping before connection.
- Verify tightening bolts are firm and plate pack dimensions are correct.
- Pipes must not subject the PHE to stress or strain.
- Avoid water hammer by not using fast-closing valves and ensuring no air remains.
- Install safety valves per regulations.
- Use protective sheets if leakage of hot/aggressive fluids or hot plate pack is a risk.
- Insulate if surface temperature poses injury risk.
- Maintain minimum free space for plate lifting.
- Install on a flat, supportive foundation.
- An elbow connection in the pressure plate, directed upwards or sideways, facilitates disconnection.
- Shut-off valves are required in all connections to allow opening the PHE.
- Ensure correct engaged threaded length for headed bolts to prevent leakage.
- Position drip tray before PHE if used.
Lifting and Raising:
- Use approved straps for lifting, placed according to diagrams, never by connections or studs.
- When raising, ensure straps are long enough for rotation without obstructions, especially considering the support column.
Operation (Start-up, Unit in Operation, Shut-down):
- Start-up:
- Check for visible leakages.
- Ensure PHE temperature is within the specified range before pressurizing.
- If below minimum gasket temperature, heat PHE slowly to avoid cold leakage.
- If multiple pumps, know which to activate first.
- Start centrifugal pumps against closed valves and operate valves smoothly.
- Do not run pumps empty on suction side.
- Adjust flow rates slowly to avoid pressure surge (water hammer).
- Verify tightening bolts are firm and dimension A is correct.
- Close valve between pump and unit controlling flow rate to avoid surge.
- Fully open vent valve at exit.
- Increase flow rate slowly.
- Open air vent and start pump.
- Open valve slowly, especially with media over 100°C, increasing temperature over at least one hour.
- Close air vent when all air is expelled.
- Repeat for second media.
- Unit in Operation:
- Adjust flow rates slowly to prevent sudden temperature/pressure variations.
- Ensure media temperatures and pressures are within nameplate limits.
- In case of safety-endangering failures, turn off flow to decrease pressure and stop heat transfer.
- Shut-down:
- If multiple pumps, know which to stop first.
- Slowly close valve controlling pump flow rate.
- Stop pump when valve is closed.
- Repeat for second media.
- For shut-down longer than several days, drain the PHE. Also drain if ambient temperature is below freezing.
- Rinse and dry PHE plates and connections if media processed requires it.
Maintenance Features
Regular maintenance is crucial for PHE longevity, including recording maintenance activities. Plate cleaning frequency depends on media type and temperatures.
Cleaning - Non-product side (CIP):
- Cleaning-In-Place (CIP) equipment allows cleaning without opening the PHE.
- CIP aims to clean fouling/lime deposits, passivate cleaned surfaces against corrosion, and neutralize cleaning liquids before draining.
- Always use proper protective equipment (safety boots, gloves, eye protection) with cleaning agents.
- Corrosive cleaning liquids can cause serious injuries.
- Residuals after cleaning must be handled per local environmental regulations. Neutralized chemicals may be drained to wastewater if fouling deposits are free of heavy metals or other toxic compounds.
- Consult Alfa Laval for CIP equipment sizing.
Cleaning Liquids:
- AlfaCaus: Strong alkaline liquid for removing paint, fat, oil, biological deposits.
- AlfaPhos: Acid cleaning liquid for removing metallic oxides, rust, lime, inorganic scale; contains repassivation inhibitor.
- AlfaNeutra: Strong alkaline liquid for neutralizing AlfaPhos.
- Alfa P-Neutra: For neutralizing AlfaP-Scale.
- Alfa P-Scale: Acidic powder cleaner for primary carbonate scale and other inorganic scale.
- AlfaDescalent: Non-hazardous acidic cleaning agent for inorganic scale.
- AlfaDegreaser: Non-hazardous cleaning agent for oil, grease, wax deposits; prevents foaming with Alpacon Descaler.
- AlfaAdd: Neutral cleaning strengthener for use with AlfaPhos, AlfaCaus, Alfa P-Scale (0.5-1 vol%); improves cleaning on oily/fatty surfaces and reduces foaming.
Chlorine as a growth inhibitor:
- Reduces corrosion resistance of stainless steels (including high alloys like Alloy 254 SMO).
- Weakens the protection layer, making steels more susceptible to corrosion.
- Exposure time and concentration are critical.
- Consult local representative if chlorination of non-titanium equipment cannot be avoided.
- Water with over 300 ppm Cl ions should not be used for cleaning solutions.
- Ensure handling of residuals after using chlorines follows local environmental regulations.
Manual cleaning of opened units:
- If CIP is not possible, manual cleaning is required.
- Opening:
- Check warranty conditions before opening.
- If PHE is hot, wait until it cools to about 40°C (104°F).
- Use proper protective equipment (safety boots, gloves, eye protection).
- Shut down and isolate the PHE.
- Drain the PHE.
- Remove protective sheets.
- Dismantle pipes from the pressure plate.
- Inspect and clean/grease carrying bar sliding surfaces.
- Mark plate assembly with a diagonal line.
- Measure and note dimension A.
- Loosen and remove locking bolts (LB) first, then tightening bolts (TB). Grease threads before loosening.
- Open PHE using tightening bolts, keeping frame and pressure plate parallel (skewing not to exceed 10 mm width, 25 mm vertically). Loosen bolts evenly (1-2-3-4 order) until all reaction forces disappear, then remove bolts.
- Open plate pack by sliding pressure plate on carrying bar. Plates usually don't need removal for cleaning.
- For M3, T2, TL3 models, be careful when moving pressure plate; use a starlock ring (part no. 33500045-45) to prevent it from passing the end of the carrying bar.
- If plates are to be numbered, do so before removal.
- Plate pack may contain residual liquid; use drainage box if necessary to avoid injury/damage.
- Cleaning:
- For deposits removable with water and brush: Start cleaning when heating surface is wet and plates are hanging. Remove deposits with soft brush and running water. Rinse with high-pressure hose.
- For deposits not removable with water and brush: Plates must be removed. Brush with cleaning agent, then rinse immediately. Long exposure to cleaning agents can damage gasket glue.
- Never use hydrochloric acid with stainless steel plates. Water with over 330 ppm Cl is unsuitable for cleaning solutions.
- Protect aluminum carrying bars and support columns from chemicals.
- Do not damage gaskets during manual cleaning.
Closing:
- Ensure all sealing surfaces are clean.
- Clean and grease bolt threads (e.g., Gleitmo 800).
- Attach gaskets to plates or check proper attachment (gasket should not rise out of groove).
- If plates were removed, insert them in alternate directions with gaskets turned towards frame/pressure plate as per hanging list. Use marked line from opening.
- Check if plates are correctly assembled (A/B/A/B pattern forms a "honeycomb").
- Press plate package together. Position tightening bolts according to figure.
- For TL6-B, position bolts 1 and 2 (or 3 and 4), tighten until reaction force is noticed, ensuring frame and pressure plate are parallel (max 10 mm skew). Position remaining bolts and tighten to same dimension.
- Tighten tightening bolts evenly (1-2-3-4 order) until dimension A is reached.
- For TL6-B, continue tightening 10 mm or less with bolts 5 and 6, then remaining bolts to same length until dimension A is achieved.
- For pneumatic tightening, use specified maximum torque (M10: 32 Nm, M16: 135 Nm, M20: 265 Nm, M24: 450 Nm, M30: 900 Nm).
- If dimension A cannot be reached, check plate count, dimension A, and ensure nuts/bearing boxes run freely; clean/lubricate/replace if needed.
- Position locking bolts, tighten, and check dimension A on both sides (top and bottom) (not valid for TL6-B).
- Mount protection sheets.
- Connect pipes.
- If PHE does not seal at dimension A, tighten further to A minus 0.5%.
- For TL6-B with ASME standard frame, tighten top and bottom bolts after or slightly before dimension A is reached.
Pressure test after maintenance:
- Strongly recommended after plate/gasket removal/insertion/exchange to confirm internal and external sealing.
- Test one media side at a time with the other side open to ambient pressure.
- Test pressure must equal operating pressure, never exceeding design pressure on nameplate.
- Recommended test time: 10 minutes per media.
- Consult local Alfa Laval representative for advice on procedure.
Regasketing:
- Clip-on/ClipGrip gaskets:
- Before removing old gaskets, note how they are attached.
- Open PHE, remove plate needing new gasket.
- Check warranty conditions before opening.
- Remove old gasket.
- Ensure sealing surfaces are dry, clean, and free of foreign matter.
- Check new gasket and remove rubber residual before attaching. Pay special attention to end plate gasket.
- Attach Clip-on/ClipGrip gasket to plate, slipping tabs under plate edge. Ensure prongs are in correct position.
- Repeat for all plates needing regasketing.
- Close PHE per "Closing" instructions.
- Glued gaskets:
- Use Alfa Laval recommended glue; separate gluing instructions provided with glue.
- Other glues may contain chlorides that damage plates.
- Do not use sharp tools to remove glued gaskets to avoid plate damage.
Other regular maintenance: Keep carrying bar, guiding bar, and tightening bolts clean and greased.
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