Note: Descriptions are shown in the official language in which they were submitted.
2~4~10~
Title: Pump System
Description.
The invention concerns a pump syste~ provided with a
displacement pump with a horizontal commuting-pipe, said
commuting-pipe being connected on one side to a feed-pipe via
a primary one-way valve to allow sucking of a quantity of
medium from the feed-pipe into the commuting-pipe, said
10 commuting-pipe being likewise connected Oll that side to a
r~moval-pipe via a second one-way valve in order to allo~
pushing of a corresponding quantity of medium out of -the
commuting-pipe, whereby said pump system possesses a bent
pipe which is connected to the other side of the commwting-
15 pipe and which is coupled to the displacement pump, and thesaid pump system also possesses a vertical pipe and heat-ex-
changing media.
Such a pump system is known from EP-A-0048535. The
known pump system is provided ~Jith a displacement pump in the
20 form of a cylinder-plunger pump, said cylinder-plunger pump
being connected to a horizontal pipe, around which pipe heat
exchanging media have been placed. The horizontal pipe is
connected to a vertical pipe. The uppermost part of said
vertical pipe is provided with a valve, said valve functio-
25 ning as a gas-pressure exhaust and being of service in taking
samples for the purpose of checking the degree of pollution
of the medium in the vertical pipe, said valve also functi-
oning as the means by which li~uid can be locally in~ected
and, furthermore, serving as a liquid-exhaust for working
30 media injected into the cylinder-plunger pump. The undermost
part of the said vertical pipe is connected to the bent pipe
via an expansion chamber~ The expansion chamber, ~hich pos-
sesses a relatively large cross-section, is provided wi-~h a
stabilising device in order to limit Reynolds' Number for the
35 flow in the said chamber to 2000. The cross-section of the
expansion chamber is greater than the cross-section of the
vertical pipe, and the cross-section of the vertical pipe is
smaller than that of the horizontal pipe.
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With the aid of the liquid injection-system, a quanti-
ty of working medium is injected into the cylinder-p:Lunger
pump, this quantity being continually greater than the leaka-
ge~losses which occur along the displacement body which moves
5 back and forth in the plunger pump. The iniection of fresh
and cool working medium maintains the necessary low working
temperature in the displacement pump, and ensures that the
medium to be pumped, which is generally aggressive and hot,
does not come into contact with the pump.
The known pump system is complicated.
The purpose of the invention is the provision of a
pump system in which a plunger-membrane pump can be used to
transport hot, erosive media (in particular, sludges which,
due to inadequate flow-rate, deposit sediment in the system)
15 and in which injection of a working medium into the medium to
be pumped does not have to occur at the installation site of
the pump system.
~ o this end, the pump system according to the inventi-
on is characterised by the fact that the displacement pump is
;~ 20 a plunger-membrane pump, that the said plunger-membrane pump
is mounted in the vertical pipe, and that the heat exchanging
media are mounted around the said vertical pipe.
At this point, it should be stated that the term
"membrane pump" ought to be interpreted as referring to a
25 pump whose operation is based on the motion of a hermetically
sealed element. The motion of this element, which, for e~am-
ple, can take the form of a me~ran~, bellows, hose, etc.,
can be effected by a pneumatically or mechanically driven
organ which is directly coupled to the said element. The said
30 motion can also be effected indirectly, meaning that the
motion of a displacement-body, such as a plunger, is trans-
ferred to the hermetically sealed element via an intervening
medium, often a liquid.
The advantage of the pump system according to the
35 invention is that, by using the membrane pump, any pump fluid
which has to be injected cannot leak through the membrane. In
this way, the vertical pipe in particular remains free of
injected medium. The embodiment of the pump system according
.
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to the invention is also simpler because of the fact that the
plunger-membrane pump is directly fitted into the vertical
pipe, around which the heat exchanging media are also moun-
ted. The result is that a horizontal pipe which, in the known
5 system, led from the pump to the vertical pipe, becomes de~
funct. Moreover, insulation of the vertical pipe is unneces-
sary, and an expansion chamber with associated stabilisation
device is no longer required.
The pump system according to the invention does not
lO require any special working medium. If a very hot medium is
being pumped, one can still inject a cooling medium if one
wishes. This cooling medium can, ~Jithout any problem, itself
be part of the medium to be pumped (~hence the cooling medium
will, of course, have to be pre-cooled somewhat). Use of a
15 working medium different from the medium to be pumped is not
really necessary.
A further advantage of the pump system according to
the invention is that the somewhat elastically deformable
angular pipe-section which includes the commuting-pipe, the
20 bent pipe and the additional pipe, can, in the event of
temperature-changes, withstand expansion ~nd contraction.
This means that, ~hen pumping media with widely varying
temperatures, the occurrance of large forces and deformations
is avoided at locations in the pump system where these would
25 be undesirable.
The said pump system according to the invention takes
up little floor space, thanks to the construction and place-
ment of the distinct components. As a result, the costs of
constructing and maintaining a housing for placement of the
30 said pump system are limited.
In addition, it is advantageous that the cross-secti-
ons of the horizontal pipe, the bent pipe and the vertical
pipe can remain the same, since, in this way, the probability
o~ blockages occurring in the pump system according to the
35 invention is considerably reduced.
A preferential embodiment of the pump system according
to the invention is characterised by the fact that the capa-
city of the commuting-pipe is larger than the stroke-volume
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of the plunger-membrane pump by a factor which is dependent
on Reynolds' Number for the medium to be pumped.
The advantage of this embodiment of the pump system
according to the invention is that the so-called turning
5 point (i.e. that point nearest the membrane pump which demar-
cates the internal volume of the commuting-pipe, said commu-
ting-pipe being filled time after time with sucked-in medium)
is located in the commuting-pipe itself. ~s a result, the
~uantity of heat given off by the hot medium will only be
10 significant in the commuting-pipe itself, and the additional
pipe does not come into direct contact with the hot medium.
In this way, the heat capacity of the heat e~changing media
can be further limited, in order to accomplish a sufficiently
low temperature near the membrane pump.
In practice, the said factor lies in the range 1.2 to
5, usually around 1.5.
It is preferable to have the radius of the bent pipe
equal to at least about 1.5 times the internal diameter of
the bent pipe.
The invention, along with its other advantages, shall
be further elucidated using the accompanying figure, which
figure shows a prelerential embodiment of the pump system
according to the invention.
The figure shows a pump system 1 which contains a
25 feed-pipe 2 and a removal pipe 3. The pump system 1 also
contains a partially sketched displacement pump ~ for suckin~
in a medium 5 (e.g. a sludge) from the feed-pipe 2 via a
primary one-way valve 6 in a commuting-pipe 7, which commu-
ting-pipe 7 is usually horizontally placed. The sucking-in of
3~ ths medium 5 occurs in a suction phase, which is followed by
a compression phase in which the medium 5 which has accumula-
ted in the commuting-pipe 7 is pushed via a second one-way
valve ~ into the removal-pipe 3, said removal-pipe being
directly connected to the commuting-pipe 7. Both one-way
35 valves 6 and 8 ta~e the form of ball valves in the depicted
embodiment; in the suction phase, valve 6 opens and valve 8
closes, whereas in the compression phase, valve 6 is closed
and valve 8 is opened.
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Point A indicates the position oE the turning point or
boundary in the commuting-pipe, ~hich point marks the positi-
on in the commuting-pipe to which medium 5 is sucked before
being removed again.
A bent pipe 9 i5 coupled to the commuting-pipe, and
coupled to the bent pipe 9 is a pipe 10 which is preferably
placed vertically. Heat exchanging media 11 are located
around the pipe 10, which media shall, in general, include a
heat exchanger through which cooling fluid can flow (in a
10 manner and with the aid of media which are not depicted in
the figure).
By placing the pipe 10 vertically, one ensures that
the turning point A in the commuting-pipe 7 stays still, and
does not move through the bent pipe 9 in the direction of the
15 heat exchanging media 11 and the pump ~. Due to the action of
gravity, the medium near the displacement pump ~ will have a
greater tendency to sink downward, thereby pushing the
turning point A toward the commuting-pipe 7, thus
guaranteeing a good and long-lasting performance of the
20 displacement pump (embodied as a plunger-membrane pump).
The membrane pump 4 possesses a membrane 12 which is
mounted in a pump housing 13, said pump housing being connec-
ted to the pipe 10. The membrane pump is provided with a
; plunger-rod 14 which is moved back and forth by fitting
25 driving media. Attached to the plunger-rod 14 ia a displace-
ment body 15 which is movable in a cylinder 16. If so desi-
red, the plunger-rod 14 can directly bring the membrane 12
into a back-and-forth motion, but this motion can also be
effected via an intervening medium 17 (shown in the figure),
30 which medium is brought into back-and-forth motion by the
displacement body 15 and which transfers this motion to the
membrane 12. The back-and-forth motion of the membrane 12
gives rise to the respective suction and compression phases
whereby the medi~m 5 is transported from the feed-pipe 2 into
35 the removal-pipe 3. The quantity of heat ~hich hereby reaches
the membrane 12 (which membrane is to be protected against
this heat) is minimal, this being due to the fact that the
relatively hot medium 5 remains at a relatively large distan-
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ce from this membrane 12. In this way, the heat ~hich iscontained in the hot medium 5 to the right of A can only
reach the area to the left of A by conduction. If the medium
to the left of A is heated, this surplus heat will be removed
5 via the heat exchanging media 11, whereby the membrane 12
will show only a slight temperature-rise as a result of
addition of the hot medium.
The membrane pump can be of the single type, working
in the manner just ~escribed, but can also be of the dual
10 type, in which case there is also an intervening medium to
the left of the displacement body 15, which medium is capable
of moving a membrane (not depicted) and driving a further
pump system. If so desired, it is of course possible to
employ multiple plunger-rods (not depicted) in parallel, with
15 single or dual type displacement pumps.
In general, the stroke-volume of the displacement pump
4 will be smaller than the internal volume of the commuting-
pipe 7, so that the boundary A shall remain situated in the
commuting-pipe 7. How much smaller depends on a factor which,
20 given the temperature of the sludge, is determined empirical-
ly via ~eynolds' Number. In practice, this factor lies in
general between 1.2 and 5. If so desired, a cooling medium
can be introduced at the upper face of the pump housing 13
(which cooling medium can be the same as the medium 5), with
25 the purpose of ensuring that the boundary ~ remains situated
sufficiently deep within the commuting-pipe and of preventing
too much heat from reaching the media 11 and the pump 4.
It is preferable to have the radius of the bent pipe 9
equal to at least about one and a half times the internal
30 diameter of the pipe 9, and, moreover, to have the diameters
of the pipes 7, 9 and 10 equal, so that the probability of
blockages is very small.
