Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to apparatus for the
transport of liquids, e.g. in a vacuum sewer system.
A conventional vacuum sewer system comprises a
waste inlet and a vacuum pump connected by a line including
a valve providing a seal in the line. The pressure diff-
erence across the valve is often about O.S atm. Opening
the valve causes evacuation of the inlet,and a plug of
waste is subjected to considerable`acceleration under the
influence of the pressure difference. On evacuation,
this plus acts like a projectile and can make the system
very noisy.
A further disadvantage of such a system is the
need to pass waste through a mechanical valve. Moreover,
since the valve is usually operated on a time-delay basis,
air may be drawn into the system unnecessarily after the
plug of waste has been evacuated from the inlet and before
the valve closes.
The flushing, cleaning and filling of conventional
lavatories, whether or not flushed under vacuum, involves
the use of a considerable amount of water. The design of
conventional lavatories is such that they are usually
constructed from porcelain, and are shaped to provide the
most advantageous flow of flushing wateT. They also
require an odour trap, usually in the form of a "U-bend".
These design features combined make a number of internal
and external surfaces which are difficult to reach for
thorough cleaning.
There may be occasions on which is is desirable
to join a vacuum-flush lavatory or a vacuum sewer system,
e.g. of the type described and claimed in International
` i i'7'7~5
Pat~t Publication No. W0 81/00102, to a conventional sewer
system operated under ambient pressure, or vice versa. For
example, it may be desired to increase the number of houses
in an area where ground conditions and topography for the
S undeveloped sites favour the introduction of one or more
vacuum-flushed system,but where a conventional system has
previously been used in the area. This may involve the con-
trasting problems of transferring liquid, e.g. effluent,
from a vacuum environment to an ambient pressure environ-
10 ment, and vice versa. Further, where waste or other liquidis transported via a pipe under ambient pressure, and the
pipe has to pass over unfavourable terrain, it may be des-
irable to use a vacuum system to transport the liquid from
one section of the pipe to another over the terrain.
International Patent Publication No. W0 81/00102
discloses and claims apparatus comprising a tank having an
inlet and an outlet; means for reducing pressure in the
tank; and an air inlet into the tank. Figure S of this
Publication illustrates an embodiment of such apparatus in
20 which a first tank (as defined) is connected via a rise
pipe to a secondary tank. The secondary tank is connected
to a vacuum pump and has an outlet through which liquid may
be discharged. When the level of liquid in the first tank
reaches the inlet to the rise pipe, a mixture of air and
25 liquid in the primary tank is drawn up through the rise
pipe under the influence of the reduced pressure.
According to the present invention, there is
provided a method for intermittently transporting liquid along
a line comprising, in order, a liquid inlet always or substant-
30 ially always submerged in the liquid, a rise pipe and a collectiontank, and in which there is an air inlet through which air can
flow into the line, which comprises operating a pump which
reduced pressure in the line and
~ i) leaving the air inlet open to the atmosphere, such
that a column of liquid is maintained in the rise pipe above the
level of liquid at the inlet, the height of the column being
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~ _,
( 11'7'7;~5~'3
determined by the reduc~d pres~ur~ drawn by the pump working
against the 109s 0~ pressure reduction caused by air inflow,
and
(ii) intermittently causing liquid to pass up the
S column and into the collection tank.
The present invention provides a method which can be
used, in general, where vacuum sewer systems are employed.
The method is of particular use in transporting liquid from a
lavatory.
When a column of liquid stands in the rise pipe,
apparatus of the invention in use may be said to exist in
a "steady state". The height of the liquid column is
determined, in the steady state, by the pressure reduction
achieved by the pressure-reducing means (for simplicity,
15 hereinafter referred to as a "pump") working against the
leak caused by allowing air to pass into the line through
the air inlet. Closure of the air inlet causes further
redution of pressure in the line and transport of liquid
` from the inlet, up the rise pripe above the steady state
20 level.
It will be appreciated that the rise pipe should
be sufficiently high to aliow a column of liquid to stand
therein in the steady state. For example, a water column
may be about 1 m. higher than the liquid level at the
25 inlet. If transport along the line is desired, the rise
pipe should not be so high that there cannot be liquid
transport when the air inlet is closed.
If desired, the air inlet may be blocked manually,
although it may be preferred to provide a valve which
30 blocks the air inlet mechanically when it is desired to
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transport liquid along the lin~. ~or ~xample, a suitable
valve may comprise a sprin~-loaded closure member, such
that the air inlet is open except when the member is caused
to close the inlet against the action of the spring.
, 5 Closure of the air inlet may be effected on a time-delay
sequence. An automatic sequence may be appropriate for
use with urinals.
If the air inlet is closed for a relatively short
period of time, a proportion only of liquid previously
lO standing in the rise pipe may be transported. If the air
inlet is closed for a relatively long time, depending on
the liquid replenishment means, the liquid seal between the
inlet and the pump may be wholly removed. The resultant
increase in pressure in the line may be used of itself to
15 cause replenishment. Similarly, re-opening of the air
inlet may be used to cause replenishment.
Any suitable means may be provided to replace
transported liquid, positively or otherwise. The replen-
ishment means may comprise, for example, a vessel or pipe
20 in which there can be a standing or continuously flowing
body of liquid such that the inlet to the transport line
can stand in the body of liquid. A standing body of liquid
may itself need replenishment once a sufficient volume of
liquid has been transported therefrom using apparatus of
25 the invention. Alternatively, replenishment means may be
designed to deliver liquid to replace that transported, only
when required. For example, a replenishment tank, or series
of tanks, may be provided, designed to deliver a predeter-
mined quantity of liquid to the inlet when, or at a short
30 space of time after, the air inlet is blocked. Such an
35 9
arrangement is particularly appropriate when a lavatory
forms the liquid inlet for apparatus of the invention. A
replenishment tank for a domestic lavatory can be mounted
in the same manner as a conventional lavatory cistern.
It will often be appropriate to discharge the
liquid transported from the column in the rise pipe into a
tank having an inlet connected to the rise pipe; an outlet
through which liquid may be removed as desired or necessary;
and which is connected to the pump. It is then convenient
10 to introduce an air inlet into the discharge tank. The
air inlet can provide the dual purpose of aerating, and
causing mechanical attrition of, any solids in the tank,
and of acting as the cause of transport, on being blocked.
Such discharge tanks are of the type described and claimed
15 in International Patent Publication No. W0 81/00102. The
novel apparatus can provide the inlet valve suggested, and
illustrated in the drawings as valve 3, in that publicat-
ion. For maximum attrition and circulation, the point of
air inlet into liquid may be surrounded by a skirt.
A replenishment tank discharging directly to the
liquid inlet of liquid transport apparatus of the invent-
ion may be connected to a liquid supply tank,e.g. via a
hydraulic leg, which is in communication withthe pump. In
the steady state, if the limbs of the hydraulic leg are of
25 sufficient length, separate columns of liquid stand in each
limb of the leg. By control of the relative heigh~s and/or
cross-sections of the limbs, closure and re-opening of the
air inlet can cause liquid to pass into the limb in connec-
tion with the replenishment tank. This effect can be used
30 to replace liquid in the transport apparatus inlet, simply
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by allowing the liquid level in the replenishment tank to
pass through an overflow outlet connected to the liquid in-
let of the apparatus.
By way of example, a "flushing" tank may be
5 present in the leg, and this tank may be connected to the
pump. The liquid inlet to the flushing tank may be a
relatively large bore connection,to the supply tank, and
the liquid outlet from the flushing tank a relatively small
bore connection, to the replenishment tank. The former
10 connéction may be of a height greater than the column of
liquid which can be maintained therein in the steady state,
but less than the height of the "column" when the air inlet
- is closed.
The flushing/replenishment tank arrangement
15 described above requires that the height of the limb above
the replenishment tank should be such that it can hold a
column of liquid, in the steady state. If it is desired
that the flushing tank, which will normally be in the apex
of the leg, is a smaller height above the replenishment
20 tank, then this can be achieved by leading the air inlet
into the flushing tank, and then into a discharge tank of
the type described. The pressure difference between the
flushing and replenishment tanks is then smaller than the
difference between the discharge tank and the inlet ~which
25 determines the height of the column in the rise pipe) by a
factor determined by the depth of the air inlet line beneath
liquid in the discharge tank.
The height or a flushing tank/replenishment tank
arrangement may be such that a lavatory can be sufficiently
30 well flushed by discharge of water thereinto, under gravity.
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Cleaning o a lavatory may be achieved by control of the
air inlet, such that the level of liquid therein is
caused to oscillate.
Individual supply tanks can be supplied with,
5 say, water from a main. The supply into each tank is
suitably monitored by, say, a conventional ball-cock. It
may also be desirable to replace liquid in a hydraulic
leg leading to a replenishment tank, e.g. into a flushing
tank of the type described, and this can be controlled as
10 desired.
A plurality of liquid inlets may be connected,
each via an associated rise pipe, to a single vacuum pump.
For example, where a discharge tank is present, liquid
removed from each rise pipe on closure of the air inlet
15 may be discharged into one such tank. It will be appreci-
ated that a single such operation will cause removal of
liquid from all the rise pipes connected to the pump. This
may be satisfactory where, for example, the liquid inlets
are a plurality of urinals but will be less satisfactory
20 where, for example, each liquid inlet is an individual
lavatory.
Further, liquid in the apparatus of the invention
may carry solids, e.g. when the inlet is a lavatory. It
may be desirable to ensure that any solids are disintegrat-
25 ed before being carried long distances through pipes inthe apparatus, in order that not all the pipes have to be
of a cross-section sufficient to allow the solids to pass
therethrough.
Where it is desired to control the transport of
30 liquid to a common discharge tank from a plurality of
il'7'7359
inlets, and/or wher~ it is dosir~d to disintegrate solids
; before transporting liquid to a discharge tank, it may be
desirable to form each rise pipe as an intermediate tank, OT
to connect each rise pipe to an intermediate tank. In the
5 latter case, the intermediate tank can be connected to the
discharge tank via a secondary rise pipe in which a column
` of liquid can be maintained,in the steady state. Attrition
of solids in an intermediate tank can be provided by an
air inlet. Difference in pressure between air inlets into
10 intermediate and discharge tanks can be achieved by provid-
ing a constricted line leading into the intermediate tank
from a point where the atmosphere is regulated by the pump.
A constricted line can also be used to provide
the pressure difference necessary to maintain columns of
15 liquid when the transport line comprises two rise pipes.
The height of~the liquid column in a rise pipe
between one liquid inlet and its intermediate tank is
then determined, in the steady state, by the pressure re-
duction caused by the pump, taking into account the pressure
20 increase caused by the air inlet and the drop in the
pressure at the constriction in the air line. Sufficient
difference in pressure can be achieved by blocking the air
inlet to cause liquid in the first rise pipe to be removed
into the intermediate tank.
In apparatus of the invention including a plural-
ity of liquid inlet/rise pipe/intermediate tank units, it
may be desirable -to use a constant pressur0 vacuum valve,
such that the treatment vacuum is unchanged on blocking the
air leak into any intermediate tank. If desired, the over-
30 pressure rom the pump may be used to aerate waste
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dischargedfrom the system, e.g. in a trickle filter.
As an alternative to the type of discharge tank
j described above, the liquid transport line may have an
outlet submerged in liquid in a discharge tank. Owing to
5 the presence of the pump, a column of liquid will then
stand in the line above the liquid level at the outlet.
Transport of liquid between the inlet and the outlet may
be controlled, if desired, by varying the cross-section of
pipes in the line, and/or by providing further air inlets,
10 e.g. between the pump and the outlet, and/or by providing
a plurality of vacuum pumps.
The invention will now be described with relation
to the use of the apparatus in transferring liquid from
a standing, or continuously flowing, body of liquid, depend-
15 ing on the level of the body. This can be achieved byproviding the inlet to the transport line in the body of
liquid and the air inlet in connection with- an opening a
small distance above the level of the line inlet. When the
level of the body of liquid is below the opening, the air
20 inlet is open and there is no transport. When the level of
the body of liquid rises above the opening, liquid or a
liquid/air mixture is drawn into the opening, the air inlet
is effectively blocked, the pressure in the line is reduced
and liquid transport through the line inlet can take place.
25 In this way, for example, apparatus of the invention can be
used to transfer liquid from an atmospheric to a vacuum
system, e.g. waste from a conventional sewer system to a
vacuum sewer system. Por this purpose, apparatus may com-
prise a primary flow pipe; a rise pipe extending into the
3q primary pipe; and a level control pipe, in parallel to the
~) ` 11''7'7;359
11
discharge pipe, both discharg~ and rise pipes being
connected to a vacuum pump.
The rise and control pipes may both lead into the
same discharge tank. A first constant pressure valve may
5 be provided in the control pipe line, which causes reduced
vacuum to be applied when the inlet to the control pipe is
` uncovered. A second constant pressure valve may be provided
to allow a higher vacuum pressure to bc applied between the
pump and the inlet to the rise pipe when the inlet to the
10 control pipe is covered. The possibility of large volumes
of air being drawn up through the rise pipe can be minimised
by providing a recess in the lowermost wall of the primary
pipe, into which the discharge pipe extends.
The invention will now be described with relation
15 to the use of the apparatus with the inten~ion of transfer-
ring liquid from a vacuum system to a system under atmos-
pheric pressure. For example, apparatus of the invention
can be used to discharge waste or other liquid from a vacuum
sewer syste~ to a conventional sewer.
For the purposes of illustration, it may be
assumed that, in use, waste or other liquid is transported
along a primary flow pipe under atmospheric conditions. A
rise pipe extends upwardly from the flow pipe and is connect-
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'7359
ed to a vacuum system, e.g. tho o~tlet o~ apparatus illust-
rated in Figure 1 of International Patent Publication No.
W0 81/00102. The risç pipe, which acts as the discharge
pipe from the vacuum system, should have an internal di-
5 ameter sufficiently large to permit the continuous sedi~ent-
ation of solid material. In the steady state, a column of
liquid stands in the rise pipe while the level of liquid in
the flow pipe is above the inlet to the rise pipe. Again,
in order to ensure that the level of liquid in the flow
10 pipe is maintained above the outlet of the rise pipe, it
will often be preferred to provide a recess in the wall of
the flow pipe, into which the rise pipe extends.
An air inlet is provided in the rise pipe, at a
point above the normal level of liquid in the flow pipe,
15 in order that air can pass into the rise pipe and aerate
the waste standing therein. In this way, standing waste
is prevented from turning septic.
Apparatus of the invention, while being applic-
able to the transport of all types of liquids, can avoid
20 the disadvantages described above when the inlet is a waste
inlet such as a domestic lavatory. The pressure difference
which is needed to maintain a liquid column in the rise
pipe need not be as great as the vacuum conventionally used
in a vacuum-flushed sewer system. For example, the press-
25 ure difference may be about 0.1 atm. Apparatus of theinvention can yet provide substantially complete, substant-
ially noiseless removal of waste in the inlet when the
vacuum above the column is increased.
Transport can be associated with the introduction
30 of materials such as disinfectants, deodorants and dyes,
and the invention provides a convenient dosing system for
such materials. The apparatus can be used for exhaust
ventilation, and allows central monitoring of undesirable
gas evolution.
By comparison with conventional vacuum transport
systems, where opening of a valve causes transport of a
plug of material and subsequent reduction in the transport
force, the present invention provides an increased
il'7'7;~59
13
transport orce when this ~s applied. This is despite
the reduction in noise associated with ballistic systemsA
Apparatus of the invention can be used with con-
siderably simpler lavatories than the conventional domestic
5 lavatory. Firstly, the system provides an odour trap and
there is no need for any conventional "U-bend". Secondly,
the lavatory does not have to be constructed in a config-
uration designed for the transport of flushing water. In
other words, apparatus of the invention does not limit the
10 shape of a lavatory which may thus be, for example, funnel-
shaped, suitably with vertical or near~vertical side-walls
above the funnel. The lavatory can be designed to minimise
the area of the surface which can become soiled, and the
configuration can be such that a small depth of water is
15 maintained, in use over this area. A funnel-shaped con- -
figuration may readily be modified to cause a swirling flow
on flushing, if desired.
AppaTatus of the invention can have wide utility
and yet require a minimum of moving parts. A vacuum pump
20 may be the only moving part, and this can be physically
separated from the or each liquid inlet. In particular,
any replenishment tank needs no moving parts. The system
not only causes transport of water but also removes air,
rather than requiring any separate fan as has previously
25 been the case in conventional lavatories. Liquid and any
waste do not have to pass through mechanical valves. While
specific applications have been described with regard to
waste transport, apparatus of the invention may also be used
to transport, for example, potable water.
3~ The point at which air is allowed to enter the
line may be permanently (e.g. in-the rise pipe), occasionally
or never in contact with liquid, whether or not during
transport. The actual inlet into the line may need to be
formed such that it allows the passage of air in one
35 direction, but not liquid in the other. It should not
allow the passage of air to a degree which prevents the
maintenance of a liquid column in the rise pipe.
11'7'7359
14
The invention will now be described by way of
example wi'th`reference`'to the accompanying drawings,
in whi`ch Figures 1 to 7 are schematic representations
of different embodiments of the inv0ntion.
Figure l shows apparatus comprising a liquid inlet
1 (wh'ich may be a lavatory bowl) connected v'ia a rise pipe
2 ~o a discharge tank 3. Reduced pressure can be main-
tained in the tank 3 by virtue of its connection, via a
line 4, to a vacuum pump ~not shown). The tank 3 also
has a liquid outlet 5. An air leak having an inlet 6
and a safe~y tank 7 is connect~ to the appaTatus by a
line 8. In use, in the steady state, a column of liquid
stands in the' rise pipe 2, to a height' h above the level
of liquid tshown as a dotted line) in the inlet 1. Liquid
lS in the inlet and the rise pipe forms a seal between the
inlet and the vacuum pump. Removal of liquid in the
column may be effected by blocking the air inlet 6. A
tank (not shown) provides liquid to replenish that removed,
without breaking the seal.
Figure 2 shows apparatus comprising a plurality of
liquid inlets 10, 11 connected'v'ia associated rise pipes
12, 13 to a discharge tank 14. Reduced pressure can be
achieved in the tank 14 by virtue of its connection,via
'~ a line 15, to a vacuum pump (not shown). The tank 14
- 25 also has a liquid outlet 16. An air pipe having an inlet
17 passes into the tank 14 and its outlet 18 is formed as
an aerator.
Figure 2 also illustrates means whereby liquid
removed from inlet 10 can be replaced. A replenishment
tank 20 is connected to a liquid-supply tank 21 via a
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` hydraulic leg compri~ing a rclatively large bore limb 22,
; a relatively small bore l~mb 23 and, between the limhs, a
~lushing tank 24. The flushing tank 24 is connected via
! an air line 25 to the discharge tank 14. The replenishment
5 tank 20 has an overflow outlet 26.
In use of the apparatus illustrated in Figure 2,
liquid lies in the inlets 10, 11 and in the tanks 20, 21
and 24 at least, while columns of liquid, the height of
which is the same as the height of the columns of liquid in
10 the rise pipes 12, 13, stand in limbs 22, 23. On closure
of the air inlet 17, liquid is transferred via the rise
pipes 12, 13 into the discharge tank 14 and via limb 22
into the flushing tank 24. At the same time, the level of
liquid in limb 23 is raised. When the liquid in any rise
lS pipe has been wholly or partially transferred to the dis-
charge tank 14, air is allowed to ente~ the system to
raise the pressure above the liqùid in both tanks 14 and
24. The liquid transferred to the flushing tank 24 via
limb 22 is thus transferred via limb 2-3 to the replenish-
20 ment tank 20 and is discharged to the inlet 10 via theoverflow 26. Re-opening the air inlet 17 permits re-
establish~ent of the "steady state" conditions prevail-
ing before the air inlet was closed.
Figure 3 illustrates apparatus having the same
25 components as that of Figure 2, except that no second
inlet/rise pipe assembly is shown. The important dis-
tinction lies in the connection of the line 15 to the
flushing tank 24. The illustrated apparatus operates in
the same manner as that of Figure 2, except that, in the
30 steady state, a lower column of liquid stands in the limb
23.
Figure 4 shows apparatus comprising a liquid in-
let 30 connected via a rise pipe 31 to an inteTmediate
tank 32. The intermediate tank 32 is connected via a
35 secondary rise pipe 33 to a discharge tank 34. The
discharge tank 34 has a liquid outlet 35, a line 36
connected to a vacuum pump (not shown) and an aerator 37.
The intermediate tank 32 and the discharge tank 34 have a
il'7';';~59
16
connectin~ air lines 38 including a constriction at 39. The
intermediate tank 32 is connected to an air inlet 40
which terminates in an aerator 41.
In use, with a vacuum pump operating and liquid
in the inlet 30, liquid stands in the rise pipes 31,35
5 to dif$erent heights, owing to the different degrees of
vacuum pulled in the intermediate tank 32 and the discharge
tank 34. The difference is the effect of the ~onstriction
; 39. Closure of the inlet 40 causes removal of liquid from
the column in the rise pipe 31 into the intermediate tank
10 32, and replenishment liquid passes into the inlet 30 from
a source ~not shown). This operation does not affect any
further waste inlet/rise pipe/intermediate tank systems
which may be connected, in a similar manner, to the dis-
charge tank 34. Accordingly, each unit can be operated
15 independently.
The illustrated rise pipe 31 can be replaced by
a lead directly into the intermediate tank 32 at any level.
The intermediate tank can function to break up solids by
attrition on aeration. The pipe 33 can thus be of
20 smaller cross-section than that of pipe 31.
Figure s shows a primary flow pipe 50, a rise
pipe 51 connected to a vacuum sewer system (not shown) at
its upper end, and an air leak 52. The rise pipe Sl
extends at its lower end into a recess 53 in the flow pipe
25 50. In use, as a means of connection between a vacuum
sewer system and a conventional sewer system, there is a
continuous flow of waste along the primary flow pipe 50,
while a column of waste stands in the rise pipe 51 and is
; discharged therethrough as appropriate. The waste standing
30 in the rise pipe is aerated by virtue of the provision of
the air inlet 52.
.
7'7~ s g
Figures 6 and 7 again show a primary flow pipe
and rise pipe 51 and ~in Figure 7) a recess 53. Figures
5 and 6 also show that the upper end of the rise pipe 51
terminates in a discharge tank 54, to which a vacuum pump
5 (not shown) is connected, and a control pipe 55 in parallel
with the rise pipe 51. Transport into the discharge tank
54 occurs, in use, when the opening into the control pipe
! 55 (which is higher than the inlet to the rise pipe 51) is
I covered by liquid in the flow pipe 50, but not when the
! lo control pipe 55 allows the passage of air only.
~ Figure 7 shows constant pressure valves 56 and 57.
¦ These valves bring reduced and normal vacuum pressure into
I play, respectively, when the opening into the control pipe
55 is uncovered and covered, respectively.
.
