MONTAGE
Les tuyaux doivent être raccordés de manière à ce que la dilatation thermique
n’affecte pas l’échangeur de chaleur au niveau des raccords. S’il existe un risque
que la pression statique puisse dépasser la pression nominale, une soupape de
sûreté doit être installée. Ne jamais exposer l’unité à des pulsations ou des
variations cycliques excessives de la pression ou de la température. Il est
également essentiel qu’aucune vibration ne soit transmise à l’échangeur de
chaleur. Si un tel risque subsiste, installez des amortisseurs de vibrations.
Utilisez une bande de montage en caoutchouc en guise d’amortisseur entre le
Minex et la bride de fixation. Le sens de pose influe peu ou pas du tout sur le
rendement du Minex.
Plusieurs solutions de montage du Minex SWEP sont illustrées ci-dessous.
a)
b)
c)
d)
a) Supporté par la base
b) Tôle métallique de support (joint en caoutchouc entre la bride et l’échangeur)
c) Barre transversale et boulons (joint en caoutchouc entre la barre
transversale et l’échangeur)
d) Pour un Minex plus petit, il est également possible de poser l’unité en la
suspendant simplement aux conduites/raccords.
RACCORDS
Suivant les normes nationales/locales et l’application, il existe différentes options
de raccordement. Il est important de disposer de raccords conformes à la norme
internationale ou nationale, étant donné qu’ils ne sont pas toujours compatibles.
La conception des raccords de Minex diffère quelque peu de celle des raccords
de CBE.
Raccords à enclenchement
La plaque de bâti du Minex dispose de fentes
spécialement conçues dans lesquelles les raccords
peuvent être insérés. Lorsque le paquet de plaques est
assemblé, les raccords sont verrouillés en position.
Le verrouillage des raccords au bâti s’effectue sans
soudure ni brasure des connexions. Cela signifie par la
même occasion que le matériau des raccords et des
bâtis peut être personnalisé suivant les préférences et
les exigences du client, par ex. un bâti en acier au
carbone anticorrosion combiné à des raccords en acier
inoxydable peu coûteux d’un côté et des raccords en
titane de l’autre.
Tous les raccords sont dotés d’un bouchon en plastique
spécial destiné à protéger le raccord fileté et empêcher
la pénétration de saleté dans le Minex. Ce bouchon en
plastique doit être enlevé avec précaution, pour éviter
d’endommager le filet, la surface d’étanchéité ou tout
autre élément du raccord. Utilisez un tournevis, une
pince ou un couteau.
Surface d’étanchéité
Raccords filetés
Exemples de raccords filetés: raccord fileté femelle/mâle, ISO-G, NPT, ISO 7/1
Raccords filetés à
l’extérieur (Mâles)
Raccords filetés à
l’intérieur (Femelle) ou
de type standard
Raccords filetés à
l’intérieur (Femelle)
avec
un extérieur
hexagonal
STRAINERS
If any of the media contain particles larger than 1 mm (0.04 inch), we recommend
installing a strainer with a size of 16-20 mesh (number of openings per inch)
before the exchanger. The particles could otherwise block the channels, causing
bad performance, increased pressure drop and risk of corrosion. Some strainers
can be ordered as accessories.
INSTALLATION OF MINEX IN SINGLE-PHASE
APPLICATIONS
Normally, the circuit with the highest temperature and/or
pressure should be connected on the left side of the heat
exchanger when the arrow points upwards. For example,
in a typical water-to-water application, the two fluids are
connected in a counter-current flow, i.e. F1 for the hot
water inlet, F3 for the outlet, F4 for the cold-water inlet and
F2 for the outlet. This is because the right-hand side of the
heat exchanger contains one channel more than the left-
hand side, and the hot medium is thus surrounded by the
cold medium to prevent heat loss.
F1
F2
F3
F4
Start-up
Make sure that the tightening measure (total plate package measurement) is
correct according to the label on the heat exchanger. Close the pump discharge
valves to the heat exchanger completely. The static pressure must be increased
slowly until the operating pressure is reached, in order to not displace the
gaskets. It is recommended that the inlet valves on both sides are opened
simultaneously to avoid over-pressure on one side. It is also important to avoid
hammering, as the elastomer gaskets may be displaced and thereby cause
leakage.
Dismantling
The pressure on both sides should be decreased simultaneously and gradually
when shutting down the unit. Remove the pipe work connected to the heat
exchanger. The tightening bolts must be loosened with the frame and pressure
plate as parallel as possible. This is most easily done with a hydraulic hand pump.
For M10:
Start to release the center nut and unscrew the bolt from the unit. NOTE! Do not
punch the bolts through the plate package as this might damage the channel
plates. Loosen the upper and lower tightening bolts max 2-3 mm (0.1 inch) at a
time, in order to keep the plate package parallel.
Since the gaskets are not glued, try to keep the plate package together. Keep the
unit lying on the back, P-side, and remove one plate at the time. The start gaskets
are made of two half-channel plate gaskets and should be removed carefully and
saved. On the M10 you also have a center ring gasket on each plate, which seals
off the center-tightening bolthole. There is only one way to place the gasket in the
groove. The start plate gaskets therefore have to be adjusted (with a pair of
scissors) to fit in to the gasket groove.
Start plate (4-hole)
with gasket
Channel plate (4-hole)
with gasket
End plate (0-hole)
without gaskets
Assembly of plates
The plates should always be mounted with the gasket facing the front frame
plate. Make sure the center ring gaskets are correctly located in the gasket
groove in the middle of channel plate. In a single-pass unit, the start plate should
always be mounted with the herringbone pattern pointing down, in the opposite
direction of the arrow on the front of the frame. Make sure to alternate the channel
plates so that every second plate has the arrow pointing up and on every second
pointing down all through the plate package.
The bolts are short in order to decrease the outline dimensions. To be able to
mount the nut on the bolt, we recommend using a screw clamp or similar tool to
tighten the unit enough
.
After this tightening, the upper and lower bolt can easily
be located in their holes. Take care that the plate package is not over-tightened as
this might cause deformation of the plates and gaskets and thus affect the
thermal performance. After dismantling and cleaning, always let the gaskets dry
for 24 hours so they can revert to their original form before assembly. This
procedure will prevent the risk of leakage and should not be ignored. The
performance of the heat exchanger and the lifetime of the gaskets depend on the
accuracy of the tightening. If leakage occurs when the plate pack is equal to the
total plate package measurement, the gaskets should be replaced instead of
further tightening.
Principle of assembly
There are a few differences such as number of plates, number of packages,
placing of connections etc. when mounting different versions of Minex. The
example below illustrates the assembly of a two-pass Minex.
Figure 1. When assembling the Minex,
start with the last channel plate. The
chevrons of the plate should point
downwards. Alternate the channel
plates so that every second plate has
the arrow pointing up and every
second pointing down all through the
plate package.
Figure 2. A multi-pass unit has a 2-hole
middle plate between the two plate
packages.
Figure 3. When mounting the second
plate package, the chevron on the first
plate should point upwards. Alternate
the channel plates as described in
figure 1. Put the second plate package
on top of the 2-hole plate.
Figure 4. The start plate, which in this
case is a 2-hole plate, should be placed
next. Observe that this plate has a gasket
covering all four corners.
Figure 5. Put the connections into the
designed slots in the front frame and
place the frame on the top of the
package with the arrow pointing up.
Figure 6. Turn the whole package upside-down and place the flat rubber gasket
between the last channel plate and the end cover plate. Please note that the flat
rubber gasket is used only for multi-pass units.
Figure 7. Put the two outer bolts and lock
washers in place and use two screw
clamps to tighten the unit in parallel.
NOTE! If the bolt gets stuck, do not
punch it through the plate package, as
the channel plates can be damaged.
The bolts must be screwed through the
plate package. Finally, put the center
bolt in place and do the final manual
tightening in parallel.
Leakage
If there is leakage when the unit is cold but no signs of leakage during operation,
no action needs be taken. If however there is leakage under normal operating
conditions, the Minex unit should be further tightened. Checked that the unit is
parallel and not out of alignment. Note that the total plate package measurement
is the absolute limit! If the unit leaks when the total plate package measurement is
reached, try to locate the leakage before disassembling in order to be able to pick
out and correct the suspected damaged plates. The gaskets have to be replaced
for all leaking plates. It is important that the frame and channel plates are parallel.
If not, this might cause leakage.
Storage of gaskets
All gaskets are to be stored under appropriate conditions. Gaskets made of NBR
have a shelf life of one year while EPDM gaskets may be stored for up to three
years. This is valid for an assembled Minex as well as separate gaskets. These
time limits are naturally not valid for a unit in service. In practice, the gasket's
lifetime depends on the application and the gasket's exposure to variations in
temperature, pressure and chemical influences, which means that it may affect
the lifetime both positively and negatively. The reason for the restricted shelf life is
that elastomers such as Nitrile and EPDM are oxidized in presence of O , O , UV-
3
2
light etc. This oxidation causes the rubber to harden and ultimately leads to small
cracks in the gaskets.
CLEANING
Thanks to the high degree of turbulence in the Minex, there is a self-cleaning
effect in the channels. However, in some applications the fouling tendency can be
very high, e.g. when using extremely hard water at high temperatures. There are
several different possibilities to clean the unit.
•
CIP cleaning (Cleaning In Place): Clean the exchanger by circulating a
cleaning liquid. Use a tank with weak acid, 5% phosphoric acid or, if the
exchanger is frequently cleaned, 5% oxalic acid. Pump the cleaning liquid
through the exchanger. For optimum cleaning, the cleaning solution flow rate
should be a minimum of 1.5 times the normal flow rate, preferably in a back-
flush mode. After use, do not forget to rinse the heat exchanger thoroughly
with clean water. A solution of 1-2% sodium hydroxide (NaOH) or sodium
bicarbonate (NaHCO ) before the last rinse ensures that all acid is
3
neutralized. Clean at regular intervals.
•
Manual cleaning: Open the unit according to enclosed dismantling directions.
When cleaning a multi-pass unit, make sure where the “2-hole” plate is
located. Since the gaskets are unglued you can easily clean the plates. Use a
fiber brush and water (do not use a steel brush or steel wool). Greasy
deposits, e.g. oil, are removed with a soft brush and paraffin (kerosene).
Organic deposits are removed with a soft brush and alkaline detergent (2%
caustic soda, 50°C (122°F)). Precipitates of calcium components may be
removed with either 10% nitric acid (HNO ) or 2% sodium
3
polymethaphosphat, 50°C (122°F), 2% sodium trimethaphosphate, 50°C
(122°F), 5% EDTA. After cleaning, the heat exchanger should be thoroughly
flushed with clean water. The gaskets, which have been deformed due to the
tightening, have to dry for 24 hours to revert to their original form before
assembly. This procedure will avoid the risk of leakage and should not be
ignored. (Note! You may want to have a spare set of gaskets on hand so you
don't have to wait 24 hours to re-assembly.)
Note that all acids and bases are hazardous and should be handled with great
care.
For further information, please consult SWEP's CIP leaflet or your local SWEP
representative.
WARRANTY
SWEP offers a 12-month warranty from the date of installation, but in no case
longer than 15 months from the date of delivery. The warranty covers
manufacturing and material defects.
DISCLAIMER
SWEP's Minex performance is based on installation, maintenance and operating
conditions done in conformance with this manual. SWEP cannot assume any
liability for Minex units that do not meet these criteria.
For further information, please consult SWEP's technical information or your
local SWEP representative.