EP0333045A1 - Vacuum sewage conveying system - Google Patents

Abstract

A collector (42) receives sewage from a water closet (43) provided with flushing mechanisms and vacuum valves. This sewage and air are sucked up therefrom by means of a liquid ring pump (P) which discharges them into the drain (44). The liquid ring is maintained by fresh water arriving via an inlet pipe (45). The invention is applicable to on-board or ground-based sewage removal systems. <IMAGE>

Description

Waste water evacuation systems have been known for a long time. Such waters often contain poorly resistant materials. They come in particular from water closet bowls. They circulate in the vacuum evacuation conduits in the form of bundles which occupy the entire section of the conduit and which are therefore called plugs. These plugs are followed by air masses which ensure their propulsion.

Compared to gravity evacuation, vacuum evacuation has three essential advantages:
- the diameters of the conduits required for vacuum evacuation are much smaller than the diameters necessary for gravity evacuation,
- unlike gravity evacuation, vacuum evacuation works regardless of the slope of the conduits. In particular, it allows the flow to go up to a maximum height corresponding to the value of the depression expressed in meters of water column,
- the evacuation of water from a closet requires only a small volume of flushing: less than 1.5 liters of water, compared to 6 to 9 liters for gravity drainage systems.

These advantages are particularly advantageous for the evacuation of water from water closets in surface or submarine ships.

Different techniques are known for generating the vacuum:
- A first known technique consists in collecting the waste water in a tank which is put under vacuum by means of a vacuum pump. The function of this pump is only to create and maintain a vacuum in the installation. So it only sucks air. To be able to drain the tank without interrupting the operation of the installation, another pump must be able to suck up the materials under vacuum, or provide sophisticated airlock systems. Furthermore, the wastewater being stored under vacuum, the aerobic degradation of the materials does not take place.
- To overcome these drawbacks, a second technique is known from French patent n ° 82 04710. It consists of completing the installation with vacuum pump by a barometric column which allows to transfer wastewater continuously from the vacuum network to a collector at atmospheric pressure. The storage tank is no longer essential. The major drawback of this technique is that it requires a significant height (5 to 10 m) between the collector and the low point of the vacuum network.
- A third known technique is described in French patent No. 2,308,742 and its American correspondent No. 4,034,421. According to this technique, a storage tank is used at atmospheric pressure. A circulation pump sucks the wastewater stored in this tank, and discharges it under pressure into an ejector, the diverging line of which returns it to the tank. The neck of the ejector is connected to the evacuation network in which it maintains the vacuum. Wastewater, air and materials are thus transferred from the vacuum network to the tank via the ejector. This technique has the advantage of leaving the storage tank at atmospheric pressure without major complication of the installation. However, it has the disadvantage of ejectors which is poor efficiency, which results in an over-power of the circulation pump, or by the multiplication of ejector / pump groups.
- Finally, a fourth known technique consists in using a vacuum pump with an Archimedes screw to create and maintain the vacuum in a tank connected to the wastewater collection network. A special screw pump capable of sucking liquids and gases has been developed for this application. This pump is not, however, capable of passing solids. The tank must therefore be equipped to sort the materials and grind them. Installation then becomes much more complex.

The object of the present invention is in particular to provide a simple system for evacuating waste water under vacuum. It also aims to make this system robust, energy efficient and directly connectable, with or without storage tank, to a manifold at atmospheric pressure, without barometric column height constraints.

In general, a system according to the invention comprises the following elements which are common, at least as regards some of their purposes for this system and for a known system produced according to the third known technique mentioned above:
a tubular collector for receiving said wastewater in the form of successive plugs, as well as air masses consecutive to these plugs and coming from the atmosphere,
- and circulation, suction and discharge means connected to this manifold to suck up these plugs and these consecutive air masses by lowering the air pressure in said manifold to a suction pressure below atmospheric pressure, and for discharging said wastewater under a discharge pressure greater than said suction pressure and sufficient to allow their discharge.

In this known system, said circulation, suction and discharge means comprise in particular said circulation pump and said ejector, the latter for constituting suction and discharge means.

Compared to this known system, the system according to the invention is characterized in that said suction and discharge circulation means comprise
- a liquid ring pump provided with a suction passage connected to said collector, a discharge passage for the evacuation of said waste water, and a water supply passage for receiving a minority flow of supply water suitable for forming and / or maintaining a liquid ring in this pump,
- And water supply means for supplying said feed water.

According to the invention, the following preferred arrangements can also be adopted, if the circumstances allow,:
- As in said known system, said means of circulation, suction and discharge also comprise a reservoir receiving and temporarily containing said waste water under a storage pressure greater than said suction pressure. In the system according to the invention, said reservoir is connected to said delivery passage of said liquid ring pump.
- A supply pipe connects a lower part of said tank to said suction passage of said liquid ring pump so as to suck up a minority flow of waste water from this tank to maintain said liquid ring, said water supply means supplying clear water and being controllable from so as to be able to stop supplying this clear water when this ring can be maintained by this waste water.
- The system further comprises valves and piping to allow, after a period of storage of said wastewater in said tank, which then constitutes a storage tank, to empty this tank under the action of suction and discharge of said pump with liquid ring.
- Said valves and pipes for emptying said storage tank comprise
an air introduction valve which, when open, communicates said suction passage of said liquid ring pump with the atmosphere,
- a separation valve which, when closed, eliminates the connection of this suction passage to said manifold,
- And a drain pipe connecting a lower part of said storage tank to an evacuation zone so that, during a storage period during which this air introduction valve is closed and this separation valve open, this pump sucks said plugs and said consecutive air masses and discharges said waste water into said tank to store this waste water there, and so that, during a draining period during which this air introduction valve is open and this valve closed separation, this same pump draws an air flow from the atmosphere and discharges this air flow into said storage tank under a drain pressure which constitutes said discharge pressure and which is higher than the pressure atmospheric and at said storage pressure, whereby this flow of discharged air itself discharges, through said drain pipe, the waste water which has been stored in this tank for a said previous storage period.
- Said storage tank is provided with an aeration valve which is located in the upper part and which is closed during said emptying period, and a drain valve which is located on said emptying pipe and which is open for this emptying period.
- Said collector is connected to said suction passage of said liquid ring pump by means of a heavy particle trap.
- The invention applies in particular to the case where the wastewater contains organic matter, the polluting power of which can be reduced by continued aeration for a suitable period of aeration. In this case, said tank is a storage tank for storing said waste water during said aeration time, and said delivery passage communicates with this tank by means of a delivery pipe opening out at the bottom of this tank, so that the air discharged by this pump rises in the form of bubbles through the thickness of the waste water stored in this tank
- Like known pumps, said liquid ring pump comprises
- a pump body having a generally cylindrical peripheral wall around a body axis,
- a rotor provided with blades, having a rotor axis and rotating in this body around this axis, the latter being offset relative to said body axis,
- a motor to drive this rotor,
a distributor constituting a wall in contact with the interior space of said pump body,
- a suction light and a discharge light pierced in this distributor,
- And a feed passage allowing water to be introduced into said body so that the water thus introduced constitutes a liquid ring driven in rotation by said blades of the rotor and pressed by centrifugal force against said peripheral wall and that separate rotating pumping chambers are formed by these blades and this ring and that they suck a fluid to be pumped through said suction lumen and discharge it through said discharge lumen. According to the invention, said suction light is sufficiently wide to contain a circle with a diameter of approximately 40 mm, so as to facilitate the suction of weak materials which can form part of said plugs.
- Like known pumps, said liquid ring pump is further provided with tubular suction and delivery passages connected respectively to said suction and delivery ports and each having an axis. According to the invention, said axis of said suction passage and preferably that of said delivery passage are substantially parallel to said body and rotor axes and their extensions pass substantially through said suction and discharge ports, respectively.

• La figure 1 représente une vue en perspective éclatée d'une pompe à anneau liquide connue.
• La figure 2 représente une vue en coupe du corps de cette pompe en fonctionnement.
• La figure 3 représente une vue du distributeur d'une pompe à anneau liquide modifiée selon l'invention, le tracé de lumières d'aspiration et de refoulement du distributeur de ladite pompe connue étant représenté en pointillé.
• La figure 4 représente une vue d'extrémité de ladite pompe modifiée, les passages d'aspiration et de refoulement de ladite pompe connue étant représentés en pointillé.
• Les figures 5, 6 et 7 représentent des vues d'ensemble d'un premier, d'un deuxième et d'un troisième systèmes selon l'invention.

With the aid of the attached schematic figures, a more specific description will now be given below, by way of nonlimiting example, how the present invention can be implemented in the context of the description which has been given thereof. above. When the same element is represented in several figures, it is designated therein by the same reference sign. It should be understood that the elements mentioned may be replaced by other elements ensuring the same technical functions.

• Figure 1 shows an exploded perspective view of a known liquid ring pump.
• Figure 2 shows a sectional view of the body of this pump in operation.
• FIG. 3 shows a view of the dispenser of a modified liquid ring pump according to the invention, the drawing of suction and discharge ports of the dispenser of said known pump being shown in dotted lines.
• FIG. 4 represents an end view of said modified pump, the suction and delivery passages of said known pump being shown in dotted lines.
• Figures 5, 6 and 7 show general views of a first, a second and a third system according to the invention.

The principle of the liquid ring pump has been known since long for pumping gas, in particular to create a vacuum in an enclosure. It is for example described a liquid ring pump known for this use and shown in fig.1 comprises a rotor 11 provided with blades 11A and driven by an electric motor 10. This rotor rotates in a pump body 12 around a axis 11B parallel to the axis 12A of this body. The gas to be pumped enters through a suction flange 13 of a flange 14. It then passes into the pump body through a suction port 15 of a distributor 16 (see fig.3). The compressed gas is finally discharged by a discharge port 17 from the distributor and discharged by a discharge flange from the flange. A liquid ring 92 (see fig. 2) consists of water which has been introduced in suitable volume into the body 12 and driven in rotation by the rotor 11. It is pressed by centrifugal force against the cylindrical wall of this body and leaves a free axial volume for gas suction and compression. It constitutes a gas seal between the rotor blades and the wall of the pump body. Two successive blades and the liquid ring delimit a rotating chamber, the volume of which is large when it passes opposite the suction light 15 and small opposite the discharge light 17.

The calories produced by the compression of the gas and by friction are absorbed by the water in the liquid ring, which must therefore be renewed to avoid excessive heating. This is why a supply of water to the liquid ring is carried out permanently by means of an orifice 19 of the flange, the water then entering the pump body through a supply orifice 100 of the distributor. This excess water radially thickens the liquid ring which continuously pours the surplus through the discharge port 17. Known advantages of this type of pump are that it is robust and not very sensitive to the presence of liquids or entrained dust. by the pumped gas.

• 1) Les lumières d'aspiration 15 et de refoulement 17 du distributeur connu 16 sont remplacées par des lumières agrandies 21 et 22 comme indiqué sur la figure 3. L'objet de cet agrandissement est principa­lement d'éviter qu'un objet ayant pu s'introduire dans le réseau sous vide puisse se bloquer à l'entrée de la lumière d'aspiration. C'est pourquoi cette lumière est agrandie jusqu'à pouvoir contenir au minimum un cercle dont le diamètre est le diamètre intérieur de la canalisation de raccordement des water-closets, soit environ 40 mm.
• 2) Pour éviter le colmatage des conduits délimités par le flasque 14 et le distributeur 16, les brides d'aspiration 13 et de refoulement 18 sont remplacées par des brides d'aspiration 33 et de refoulement 34 présentant des orifices de diamètre plus importants percés sur la face du flasque 14, de manière que leurs axes soient paral­lèles aux axes 11B du rotor et 12A du corps de pompe, et qu'ils intersectent les lumières d'aspiration et de refoulement 21 et 22 dans la zone où elles ont été agrandies.

According to the invention a similar pump is used to aspirate and discharge a water-based mass. It turned out that this pump lent itself to the transit of soft materials which, entering the pump body through the suction port 15, are chopped by the blades of the rotor 11. The grinding is made possible by the robustness of the rotor which equips this type of pumps. To facilitate the transit of materials and avoid blockage of the pump, it is adapted as follows:

• 1) The suction 15 and discharge 17 lights of the known distributor 16 are replaced by enlarged lights 21 and 22 as indicated in FIG. 3. The object of this enlargement is mainly to avoid that an object having been able to s '' entering the vacuum network can be blocked at the inlet of the suction light. This is why this light is enlarged until it can contain at least one circle, the diameter of which is the inside diameter of the water-closet connection pipe, ie about 40 mm.
• 2) To prevent clogging of the conduits delimited by the flange 14 and the distributor 16, the suction 13 and discharge 18 flanges are replaced by suction 33 and discharge 34 flanges having larger diameter holes drilled on the face of the flange 14, so that their axes are parallel to the axes 11B of the rotor and 12A of the pump body, and that they intersect the suction and discharge ports 21 and 22 in the area where they have been enlarged.

FIG. 5 shows a first system in which the liquid ring pump is connected to a vacuum water collection network for wastewater. This network is shown schematically by a collector 42 to which is connected a water closet bowl provided with a flush and a vacuum-tight discharge valve. This flush and this valve are of known types and are not shown. The suction flange 33 is connected to the collection network. The discharge flange 34 is connected via the pipe 41 directly to the discharge pipe or sewer 44 which is at atmospheric pressure. The operation of the liquid ring pump requires a low flow water supply, intended to maintain the volume of the liquid ring and to ensure cooling. This supply reaches the supply port 19 of the pump by means of the conduit 45, the flow rate being regulated by the valve 46.

In the system which has just been described, the liquid ring pump ensures the transfer of gases, water and solid materials from the vacuum network to the sewer 44 at atmospheric pressure, as well as the grinding of these solid materials. The advantages of the invention appear clearly since on the one hand a single rotating machine is sufficient to ensure the triple function of vacuum pump, water pump, and crusher, that on the other hand the storage tank is not essential and that finally the electrical power installed and consumed is much lower than the power required for an installation with ejectors of the same suction capacity.

According to a preferred arrangement also shown in FIG. 5, a trap is placed upstream of the liquid ring pump to retain very heavy particles, such as for example metallic objects, which could have been introduced, by accident or maliciously, into the wastewater collection system which could damage the liquid ring pump. This trap can be constituted by a simple box 51 through which the wastewater transits, the inlet / outlet orifices 52 and 53 being placed at the top of the box so that heavy objects fall to the bottom of the box and fail at the pump. The box can be emptied periodically by means of an inspection hatch 54.

According to another preferred arrangement also shown in FIG. 5, it is useful to set up between the vacuum network and the liquid ring pump a non-return valve 55, and upstream of the valve a vacuum switch 56 capable, by via a relay 57, to start the pump on a high pressure threshold and to stop it on a low pressure threshold. Thus, when the sanitary installation is used little or not at all, the liquid ring pump stops when the low pressure threshold is reached, and the valve closes, thereby isolating the vacuum installation. Depending on the frequency of use of sani devices shut up, the void gradually breaks. The pump then resets to the high pressure threshold and evacuates the water and the materials accumulated in the pipes.

A drawback of the first system which has just been described according to the invention is the need to supply the liquid ring with clear water, which penalizes the water consumption of the entire installation. To overcome this drawback, it is preferable to introduce, between the pump and the evacuation manifold of a second system according to the invention, a storage tank 61 as indicated in FIG. 6. This tank is provided with 'a ventilation chimney 62 and a drain pipe 63 closed by a valve 64. The tank is emptied either periodically or continuously, by any means not described here, without the level falling below a minimum level located above the supply nozzle of a pipe 65 connecting the base of the tank to the suction pipe 66 of the liquid ring pump. Thus, the liquid ring can be supplied by recirculating part of the wastewater, the flow in the conduit 65 being effected without an auxiliary pump, under the effect of the vacuum created by the liquid ring pump. A supply of clear water 45 is however necessary in the start-up phase of the pump. This supply is then cut by the valve 46.

In such a system comprising a storage tank, another preferred arrangement also shown in FIG. 6 consists in extending the discharge line 71 of the liquid ring pump to the bottom of the tank. Thus, the air discharged by the pump escapes from the discharge pipe in the form of bubbles. This bubbling is conducive to aerobic degradation of the materials contained in the tank.

In a third system according to the invention shown in FIG. 7, the liquid ring pump is also used for emptying the storage tank. More particularly, here a temporary use is made of a liquid ring pump which is known in itself and according to which such a pump can operate as an air compressor. To perform a drain on closes a separation valve 81 through which the storage tank is connected to the vacuum network and an air introduction valve 82 is opened which allows communication with the atmosphere. The pump then sucks in air at atmospheric pressure which it compresses by discharging it into the tank. We also closed a valve 83 located on the tank ventilation chimney. If a tank drain valve 84 is then opened, it results in a pressure drain of the latter. It is thus possible to discharge the waste water into a drain pipe 86 to a collecting duct 88 located higher than the tank.

Claims (10)

1 / Vacuum wastewater evacuation system in which the wastewater is sucked in and discharged by a liquid ring pump. 2 / Wastewater evacuation system comprising
- a tubular collector (42) for receiving said wastewater in the form of successive plugs, as well as air masses consecutive to these plugs and coming from the atmosphere,
- and circulation, suction and discharge means connected to this manifold to suck up these plugs and these consecutive air masses by lowering the air pressure in said manifold to a suction pressure below atmospheric pressure, and for discharging said wastewater under an evacuation pressure higher than said suction pressure and sufficient to allow their evacuation,
this system being characterized by the fact that said means of circulation, suction and delivery include
- a liquid ring pump (P) provided with a suction passage (33) connected to said collector, with a discharge passage for the discharge of said waste water, and with a water supply passage for receive a minority flow of supply water suitable for forming and / or maintaining a liquid ring in this pump,
- And water supply means (45, 46) for supplying said feed water. 3 / System according to claim 2, wherein said circulation, suction and discharge means further comprises a reservoir (61) receiving and temporarily containing said wastewater under a storage pressure greater than said suction pressure, this reservoir (61 ) being connected to said delivery passage (34) of said liquid ring pump (P). 4 / System according to claim 3, characterized in that a supply pipe (65) connects a lower part of said tank (61) to said suction passage (33) of said liquid ring pump (P) so sucking a minority flow of wastewater from this tank to maintain said liquid ring, said water supply means (46) supplying water clear and being controllable so as to be able to stop supplying this clear water when this ring can be maintained by this waste water. 5 / System according to claim 3, characterized in that it further comprises valves (81, 82) and pipe (86) allowing, after a period of storage of said wastewater in said tank which then constitutes a storage tank (61), to empty this tank under the suction and discharge action of said liquid ring pump. 6 / System according to claim 5, in that said valves and pipes for emptying said tank comprise
an air introduction valve (82) which, when open, communicates said suction passage (33) of said liquid ring pump (P) with the atmosphere,
a separation valve (81) which, when closed, eliminates the connection of this suction passage (33) to said manifold (42),
- And a drain pipe (86) connecting a lower part of said storage tank (61) to an evacuation zone (88) so that, during a storage period during which this air introduction valve is closed and this separation valve open, this pump sucks said plugs and said consecutive air masses and discharges said waste water into said storage tank to store this waste water there, and so that, during a draining period during which this valve the air introduction valve is open and this separation valve closed, this same pump sucks in an air flow from the atmosphere and discharges this air flow into said storage tank under a drain pressure which constitutes said discharge pressure and which is higher than atmospheric pressure and said storage pressure, whereby this flow of discharged air itself discharges, through said drain pipe, the waste water which has been stored in ns this tank during a so-called previous storage period. 7 / System according to claim 6, characterized in that said storage tank is provided with an aeration valve which drain, and a drain valve (84) which is located on said drain pipe (86) and which is open during this drain period. 8 / System according to claim 3, for the evacuation of waste water containing organic matter whose polluting power can be reduced by aeration continued for a suitable aeration time, this system being characterized in that said tank is a storage tank (61) for storing said waste water during said aeration time, and said delivery passage (34) communicates with this tank via a delivery pipe (71) opening at the bottom of this tank, so that the air discharged by this pump rises in the form of bubbles through the thickness of the waste water stored in this tank. 9 / The system of claim 1 wherein said liquid ring pump (P) comprises
- a pump body (12) having a peripheral wall (12B) generally cylindrical around a body axis (12A),
- a rotor (11) provided with blades (11A), having a rotor axis (11B) and rotating in this body around this axis, the latter being offset with respect to said body axis,
- a motor (10) for driving this rotor,
- a distributor (16) constituting a wall in contact with the interior space of said pump body,
- a suction light (21) and a discharge light (22) drilled in this distributor,
- And a feed passage (19) allowing water to be introduced into said body so that the water thus introduced constitutes a liquid ring driven in rotation by said blades of the rotor and pressed by centrifugal force against said wall peripheral (12B) and that separate rotating pumping chambers are formed by these blades and this ring and that they suck a fluid to be pumped through said suction light and discharge it through said discharge light,
- this system being characterized by the fact that said suction light tion (21) and wide enough to contain a circle with a diameter of about 40 mm, so as to facilitate the suction of weak materials which may form part of said plugs. 10 / The system of claim 9, wherein said liquid ring pump (P) is further provided with tubular suction passages (33) and discharge (34) connected respectively to said suction ports (21) and discharge (22) and each having an axis (33A, 34A),
this system being characterized by the fact that said axis (33A) of said suction passage (33) and preferably that (34A) of said discharge passage (34) are substantially parallel to said body (12A) and rotor (11B) axes ) and that their extensions pass substantially through said suction (21) and discharge (22) ports, respectively.

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