Note: Descriptions are shown in the official language in which they were submitted.
2~2~
The present invention is related to cleaning equipment ~or a heat
exchanger of the so-called jacket-pipe section type with built-in
baffles and containing a jacket fitted with an inlet and an
outlet for a medium which circulates through the jacket and a
number of pipes fitted in the jacket parallel with the jacket's
longitudinal axis and supported by built in baffles.
When a liquid or gas is led through heat exchangers, soot or
other particles will always be deposited. For example, when gas
is used in the jacket and water in the pipes, soot will be
deposited on the outside of the pipes and after a period of time
efficiency will be reduced. It is consequently necessary to clean
the outside of the pipes at regular intervals.
One disadvantage of pipe heat exchangers i5 that they are relati~
vely complicated to clean for encrustation. Pipe heat exchangers
are usually cleaned by flushiny both the jack~t and the pipes in
countercurrent direction with a ~luid, possibly with an added
anti-encrustation solvent. Another method i5 to clismantle the
whole heat exchanger and clean the baffle~ and the pipes mechani-
cally. However, both these methods req~lire that the heat
exchanger be disconnected from the prosess, which is relatively
expensive and laborious.
The objective of the present invention is thus to produce
cleaning equipment which makes it possible to clean the heat
exchanger e~ficiently and speedily during operation.
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After having examined alternative cleaniny methods, the inventors
reached the surprising conclusion that it would be possible to
use the main pipe and the ba~fles as part of a cleaniny device.
Both the main pipe and the baffles are already part o~ the heat
exchanger itself, and it would consequently not be necessary to
make further changes to the heat exchanger jacket unit. The
design of spiral heat exchangers is such that the whole pipe
section is fitted around a main pipe which secures the baffles.
The inventors were therefore of the opinion that it would be
possible to scrape the outside of the pipes free of encrustation
by pulling/pushing the baffles forwards and backwards over the
pipes. The baffles had to be modified by enlarging the bores for
the pipe insertion holes to such an extent that there would be a
clearance all around the pipe. In addition, all baffles were
stiffened to prevent them from being displaced. Furthermore, the
baffles were secured in the main pipe thus allowing for all the
baffles to be moved over the outside of the pipes by pulling/
pushing the main pipe out/in. The necessary displacement length
for the main pipe was equivalent to the distance between two
adjoining baffles. The whole length of the pipes could conse-
quently be scraped. As an alternative design the inventors
discovered that it was possible to mount circular brushes at the
pipe holes of the ba~fles. In addition to an increase in cleaning
efficiency, the brushes also reduced the necessity o~ making pipe
holes with extremely low tolarances.
Another possible so.lution o~ the problems related to the pipe
inserti.ons is to mount a pipe casing in the baffle holes. These
pipe casings have an :internal diameter adjusted to the pipes'
external diameter and an external diameter adjusted to the
baffle's hole. When the pipe is pulled forwards and backwards
through the inside of the casing, the outside of the pipe will be
scraped free of any encrustation. The casings have a smaller
diameter than the holes in the baffles so that they will ~it
concentrically with the pipes. This pre~ents the pipes from be-
coming stuck in the casings in connection with the baffles being
moved back and forth.
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Pulling/pushing the baffles forwards and backwards o~er the pipes
can be achieved in a number o~ ways, for example by using motor
power or a hydraulic or pneumatic cylinder which is directly
connected to the main pipe. In connection with the use of hydrau-
lic or pneumatic operation the cylinder may be placed outside the
end bottom of the heat exchanger, or it can be mounted internally
as part of the main pipe. The hydraulics can be operated by
external oil/gas pres.sure or, by using a pump, the pressure for
either the inflowing liquid or yas can be used to operate the
cylinder. The choice of solution for operation of the main pipe
depends, among other things, on where the heat exchanger is to be
used.
The sweeping operation can be controlled in a number of ways. The
baffles can be moved over the pipes automatically at fixed inter-
vals or depending on the outflow temperature of the medium, as an
increase in the medium's outflow temperature would indicate poor
heat transfer due to pipe encrustation. After each scraping/
sweeping, the scraped off encrustation flows out with the gas or
falls to the bottom of the heat exchanger from where it can be
removed with a mechanical device such as a scraper, a screw, etc.
The invention covers all types of ba~fle heat exchancJer w ih~o~
without a main pipe. A baffle heat exchanger withouk a main pipe
has to be modified by the baffles being stif~ened and attached to
a joint bar which links all the baffles together. Furthermore, it
will be necessary to mount one or more push/pull bars on the end
baffle which is/are, ~or example, operated by a hydraulic device,
as previously described.
The invention has been defined in the attached patent
requirements and will be described in the following in relation
to the drawings which show a detailed example of the design of
a baffle heat
exchanger.
More precisely fig. 1 shows a schematic cross-section through the
heat exchanger with the main pipe, baffles and an attached
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hydraulic cylinder.
Fi~. 2 shows a cross-section AA of the heat exchanger~
Fig. 3 shows an enlarged section of a baffle with a bar, pipe and
casing.
Fig. 1 shows a schematic section of a heat exchanger 7 consisting
of a jacket 1 with an inlet ~ for the inflow of the heating me-
dium, which is gas in the example shown. In this example the
inlet 2 and an upper inlet part (a vapour belt) 3 and the jacket
1 have been insulated with a fire-proof substance. This is done
because the inflowing medium may have a temperature of up to
approx. 1000C. Furthermore, an outlet pipe 5 for the cooling
medium, in this ca~e water, is connected to an end lid 6. The end
lid 6 i5 secured to the jacket 1 by flanges 8. At the other end
there are an inlet pipe 9 for the cooling medium and an outlet
pipe 10 for the heating medium. Inside the jacket a main pipe 11
has been concentrically fitted to the pipe section as shown in
fig. 2. The baffles 12 carry the pipes 13 as they are fitted with
a number of openings 19 through which the pipes run. The baffles
have been adjusted exactly in accordance with the reference line
both in relation to each other and the pipes. The pipes are not
fixed to the baffles but are mounted freely. In turn, the pipes
have been welded or fixed in another way to the pipe plates 18.
The baffles are mutually secured by khe bars ~4 stretchirlg
through all the baffles. This can be seen more clearly in fig. 3
which shows a section of a baffle 12 with bars 14, pipes 13 and
pipe casinys 16.
The pipe casings 16 are placed in the baffle holes. The pipe
casings have an internal diameter which has been adjusted to the
external pipe diameter, and an external diameter which has been
adjusted to the baffle diameter. The casing is secured in the
baffle holes by two end stops which prevent the casing fxom being
pulled out of the baffle when the pipes are pulled/pushed
~orwards and backwards. The movement of the casings will also
contribute to cleaning the baf1es.
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The main pipe 11 i~ attached to a hydraulically-conkrolled arm ~0
allowiny the main pipe to be pulled/pushed forwards and
backwards.
At the same time this has the effect that all baffles which are
connected to the main pipe will also be pulled/pushed forwards
and backwards over the pipes and consequently scrape/brush any
encrustation of the pipes. The hydraulic device can be controlled
automatically, for example on the basis of the outflow
temperature of the heating medium measured with a sensor. If the
flow quantity and the inflow temperature are constant, an
increase in the outflow temperature registered by a sensor will
indicate a reduction of the heat transfer between the media due
to pipe encrustation. The hydraulic device can thus be activated.
Other solutions are to control the hydraulic device manually or
automatically at regular intervals. With these solutions it will
be necessary neither to dismantle the heat exchanger nor to stop
the process for cleaning. Cleaning can be carried out during
operation.
As mentioned, the majority of the scraped off material will be
led out through the outlet pipe along with the water/gas. A screw
17, however, leads heavier, scraped off particles out of the heat
exchanger, as shown in the figures. In case of scraped off
encrustation which can be melted, it is, moreover, possible to
fit a heated jacket part at the base of the heat exchanger. rn
this case the heat exchanyer may be fitted with a-va].ve for
draining out the molten encrustation.
Even if the invention primarily covers cleaning equipment for a
heat exchanger, it is also within the scope of the invention to
cover the same type of cleaning equipment adjusted to be used in
a boiler.
With the present invention equipment is available for cleaning a
baffle pipe heat exchanger with the heat exchanger remaining in
full operation during cleaning of the outside of the pipes.
The equipment is very simple to use and easy to install.
