Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF ~HE INVEN~ION
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The invention rela-tes -to a vacuum plant for
ships, for -the removal of pollu-ted water. In known
plant a vacuum pump is connected to a collecting
container at the suction side, one or more polluted water
ducts (with inlet valves) opening ou-t into this collect-
ing container, the said valves controlling the suction of
polluted water and air into the ducts and into the
collecting container.
Vacuum plan-ts for the removal of polluted water
are suitable for ships because they allow freedom in the
layout of the ducts. ~he design and layout of the duc-ts
can take into account the particular spatial conditions
prevailing in the given instance; there is no need -to
produce a pressure head; and smaller duc-t cross-sections
can be used. Vacuum plants for the removal of polluted
water of the kind in question are described, for example,
in German Patent Specification No. 1,238,858 and in
German laid-open Specifica-tion No. 24 55 551.
As correct operation of the vacuum plan-t for -the
removal of pol-luted water depends, inter alia, on the
vacuum level prevailing in the system, both the vacuum
pump and also the polluted water ducts have hitherto been
connected to the collecting container above the highes-t
possible water level, so that the suction side of the
vacuum pump was in direct communication with the polluted
water ducts above -the space in the collecting container
and above the water level in this container. However,
no attention was devoted to the aeration of the polluted
wa-ter~ Attention was merely devoted to the question of
maintaining as small as possible the flow resistance
between the vacuum pump and the polluted water ducts and
also to the question of precluding the chances of back-
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` flow. When, as is fre~uently the case on ships, the
polluted water, containing faeces, has been passed to a
clarification plant, a special aeration process took place,
by means of compressed air and in conjunction with the
clarification process1 for the purpose of promoting -the
aerobic decomposition procedllres. However, this aera-
tion did not affect those coarser solid componen-ts of the
polluted water which were retained, for example by sieves,
before the clarification plant, and which were then
separated from the polluted water.
SUMMARY OF THE INVE~r~IO~
; Underlying this invention is the object of
providing a vacuum plant, which serves for the removal of
~; polluted water and which is of the kind defined at the
; 15 outset of this specification, in which aeration of the
polluted water is appreciably improved withou-t entailing
additional expense. It is proposed according -to the
invention and for realising -this object, that the polluted
water duct shall arrive from a higher level and -then open
20 out near the bottom of the collecting container.
As a result of this provision, proposed according
-to -the invention, the air, which is suctioned by way of
the polluted water duct and which is in the form of
bubbles, must "bubble through" the volume of polluted
25 water present in the collecting container before this air
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is sucked ou-t of the collecting container by way of the
vacuum pump. Accordingly, there is achieved, in the
s collecting con-tainer itself, not only strong turbulence,
particularly of the sediment, but also continuous aera-
` ~0 tion of the polluted wa-ter in the collecting container.
The water receives air in dissolved form, and air bubbles
continue to adhere to the constituents of the polluted
water. The desired aerobic decomposition processes
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start to take place immediately; indeed, these decomp-
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osition processes take place at all the components of the
polluted water removed from the collection points includ-
ing those components which are not directly passed, in
the ship, to a clarification plant.
~ 5 In dependence on the par-ticular design of the
; clarification plant communicating with the vacuum plant
for the removal of pollu-ted water it is possible, when
the provisions of the present invention are adopted,
either to reduce the separate aeration process, which has
hitherto been carried out in the plant for the removal of
polluted water, or possibly to dispense with this aera-
tion process completely.
With regard -to the operation of the vacuum plant
for the removal of polluted water, it has surprisingly
' 15 been found that the operation of this plant for the
` removal of polluted water has even been improved by means
of the invention. ~he additional flow resistance,
presented at the collecting container by the modification
to the duc-ting layout, or the loss in pressure, cost
practically no energy, as, on account of the relatively
short length of the polluted water ducts on a ship, the
; suction force - hitherto present at the inlet valve,
;~ through which the polluted water, which accumulated at
! : toilets and at other collection points for the polluted
water, was sucked into the vacuum ducting system - was so
- great that even when the inle-t valves were opened only
for a very short period of time, larger quantities of air
than were necessary were suctioned in the normal case,
and the suction flow was so powerful that it produced
undesirably loud noises. In this respect 9 when the
provisions of the present invention are adopted, the
water, through which the air has to flow and which is
present in the collecting container and in the end of the
polluted water duct, presents a resistance which is
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altogether of benefit and which somewhat reduces the power
of the reactions o~ the plant when an inlet valve is
opened for a short period of -time.
It is also feasible, as an alternative to -the
inventive proposal, to arrange for all the polluted water
duc-ts to be connected to the collecting container at the
upper portion of the lat-ter and, in the course of the
further pa-th of travel of the polluted water, to thrust
the air, expelled from the pressure side of the vacuum
pump, through the polluted water after the collecting
container. However, this procedure would entail the
drawback of a decreased efficiency, as vacuum pumps should,
insofar as is possible, not operate with counterpressure.
BRIEF D~SCRIP~IO~ OF l'HE DRAWINGS
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Embodiments of the inven-tion are described below
with reference to the accompanying schematic drawings,
in which:-
Fig. 1 illustrates a first embodiment, wi-th a
polluted water duct which en-ters a collecting container
from above the latter; and
Fig. 2 illustra-tes an embodiment with a polluted
water duct which is connec-ted to the bottom of the
collecting container and enters the latter from below
after descending from a higher level.
D~AILED D~SCRIP~IO~ OF THE PREF~RRED ~MBODIME~S
~ oth Fig. 1 and Fig. 2 only show the collecting
container, designated as 10, of a vacuum plant for the
removal of polluted water, this vacuum plant being
installed on a ship and having a single polluted water
duct 12. It is to be understood that a number of ducts
may be branched onto the duct 12 for the purpose of
leading polluted water -to the collecting container from a
number of toile-ts and other points from which the polluted
water is collected. Alternatively, a number of polluted
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` water ducts 12 could individually lead to the collecting
container 10~ ~or the sake of simplicity, in the embodi-
ment shown in ~ig. 1 only a single toilet 14 is shown, an
inlet valve 16 being arranged from this toilet 14. ~he
ac-tuation of the inlet valve 16 may take place automatic-
ally by means of the underpressure present in the system,
when a certain quanti-ty of polluted water has accumulated
upstream of the valve. ~he inlet valve 16 may be so
~ controlled that, each time the valve opens, a specified
i 10 amount of polluted water - and, also, a specified volume
of air, which should be a multiple of the quantity of
polluted water - is admitted into the polluted water duct
12 before the valve automatically re-closes. With
reference to the con-trol of the inlet valve 16 reference
is made to German laid-open Specification ~o. 24 55 551,
referred to earlier in this specification. Instead of
the sys-tem whereby the inle-t valve 16 opens automatically,
i-t is also possible, as is known in the case of vacuum
toilets, to provide an opening mechanism which can be
actuated at will; however, it is also preferable if the
; opening dura-tion can be adjusted to a fixed value so as
to prevent losses occurring through the inlet valve being
open too long.
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~he underpressure in the collecting container 10
and in the network of polluted water ducts 12 is produced
by a vacuum pump 18 and is maintained during operation of
the plant for the removal of polluted water. ~he under-
pressure causes the polluted water, which has been
admitted into the duct system by the inlet valve 16, and
also the air which has been admitted, to be sucked into
j the collecting container 10. Whereas the air is immed-
;; iately removed from the collecting con-tainer 10 by the
vacuum pump 18, the polluted water accumulates, and thus
attains a greater volume in the collecting container 10,
before it is pumped out of the collecting container 10 by
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one or more conven-tional polluted water pumps (not shown),
and is passed to (for example) a clarification plant.
A clarification plant of this kind usually has a number of
stages in which take place, for example, the successive
steps of primary clarification, aera-tion, biological
purification, and secondary clarification. Conveniently,
a sieve is arranged upstream of the polluted water pump,
which also serves to comminute the solid components of the
polluted water, this sieve retaining the coarser compon-
ents of the polluted water, so that these coarser compon-
en-ts can be removed from the water.
As is clear from Fig. 1, the polluted water duct
12 leads, from above, into the polluted water container
10, which is completely closed and kept under vacuum,
this duct 12 -terminating close to the bottom of the
collecting container and below the wa-ter level of the
latter. ~he underpressure produced by the vacuum pump
18 is propagated to the polluted water duc-t 12 through
the pollu-ted wa-ter present in the collecting container 10
When the inlet valve 16 is closed there is hardly any
difference between the underpressure in the polluted water
duct 12 and in the upper area of the collec-ting container
10 above the water level in the latter. Consequently,
the water level is almost the same in the foremost end
of the duct 12 and in the collecting container 10.
~ he arrangement, shown in Fig. 1, of the down-
stream end of the polluted wa-ter duct 12 relative to the
collecting container 10 is such that the suctioned air
must pass the volume of water present in the collecting
container 10 before this air can be removed, by suction,
by -the vacuum pump 18. A guide and distribution device
20 may be provided for effecting a better dis-tribution of
the air in the polluted water contained in the collecting
container 10. In the embodiment shown in Fig. 1 this
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device 20 has the form of a flange which is located at
the end of the duct 12 and which surrounds -the la-tter.
~his flange may possibly also be perforated.
It may be recommendable to arrange for that part
of the polluted water duct 12 which debouches into the
collecting container 10 - polluted water thus being
present in this particular part of the polluted water
duct 12 - to be of greater cross-section th~n the
remaining part of the polluted water duct 12; in this
w~y it is possible to reduce the flow resistance pres-
ented to the air by the water contained in the downstream
end of the duct 12. ~his is illustrated in ~ig. 2.
As is readily apparent from Fig. 1, the down-
stream end of the polluted water duct 12, which extends
downwardly into the collecting container 10, does no-t
have to be in the form of a tube or hose. ~hus, the
collecting con-tainer 10 may, by the shape given to it,
;itself form the downstream end of the polluted water
duc-t 12. ~or example, this modification may be such
that a partition wall extends transversely through the
collecting container and runs from the upper closure wall
-to a point lying close to the bottom of the collecting
container, the polluted water duct 12 debouching on one
side~of this partition wall within the upper closure
; -25 wall of the collecting container, while the vacuum pump
`18 is connected to the collecting container on the
opposite side of the partition wall~ If this modifica-
tion is adopted the air arriving from the polLuted water
duct 12 will be sucked, under the partition wall, through
~30 the water contained in the collecting container 10.
~ he embodiment shown in ~ig. 2 differs from that
shown in ~ig. 1 in that the polluted water duct 12 passes
to the inner region of the collecting container, close -to
the bottom of this collecting container, outside the
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., collecting container 10 and, agaln, leads to this point
. from above the maximum water level in the collecting
.. container. ~he construction and arrangeme:nt of the
s remaining part of the polluted water duct are of no
' 5 significance for the purposes of the invention. In this
i respect use may be made of experience hitherto gained,
wi-th alternately rising and descending duct sections.
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