FR2837244A1 - Pump, for a drainage system, is controlled according to the liquid flows to ensure that there is no dry running - Google Patents

Abstract

The pump assembly for liquids in drains etc., where the liquid level is variable, is between an inflow pipe (200) and an outflow pipe (2000) with a main conduit pipe linking the outflow with the inflow. The main conduit pipe has a sealed connection at the inflow to take in a given volume for a continuous transfer to the pump. The pump operation is structured to adjust its working, according to the inflow volume. A pulsator (524) is at the upper pump body (534), driven by a motor (504,506), to give a tailed vortex propulsion. A sensor (804) registers the liquid level, with its signals transmitted to a control unit (904).

Description

deviation device (a) is adjustable.

  The invention relates to devices and installations for pumping liquid.

  pumping of liquid, in particular for gravity networks.

  The installations are involved in particular in sewerage, rainwater and industrial effluent collection networks. Wiles act as a relay to overcome the distances and topographic obstacles that separate the effluents from their destination. Wiles allow, for example, to collect and transport wastewater to

treatment plants.

  The effluents circulate in pipes according to the slope which is imposed on them. When this slope has an excessive inclination, a pumping installation, of the pumping station or lifting poses type, raises the effluent from a level lower to a higher level, and the effluent can

  then resume its flow in pipes.

  In known installations, the pumping device comprises several submersible pumps, placed in a common tank, and connected to a piping installation. The pumps can operate simultaneously or as back-up

each other.

  When the device has a failure, its renovation

  imposes a complete interruption of pumping. This interrup-

  tion causes effluent overflows. In the case of a wastewater lift, these overflows are accompanied by spills in neighboring stormwater networks,

that pollute the natural environment !.

  To ensure continuity of service during the renovation works, other pumping stations provide an emergency pump. This emergency pump requires creating a look upstream of the station. Another solution is to use an expensive rotation of emptying trucks, throughout the duration of the work. In still other embodiments, it is known to build a second pumping station intended to provide pumping to compensate for a possible failure of the first. This behind solution doubles the initial cost of the installation, which is

very important.

  In addition to the problems associated with the renovation of pumping stations, known pumping installations have other drawbacks. In known embodiments, the waters coming from a gravity network are poured out at the bottom of

  the tank until they reach a deter-

  mine, correspond to a loading volume. When this height is reached, two separate pumps prime to empty this charge volume and discharge it to an outlet pipe of the same network. This level detection pumping, also called "tarpaulin pumping", is

  intended to regulate the incoming waters.

  Dry running of the pumps is observed when the pump receives a liquid having a substantially zero flow rate. The

  existing wind projects generally fitted with packing

  fragile and expensive mechanical resins for sealing pumps, which require regular lubrication. However, this lubrication is not ensured in operation to see, which reduces the tightness of the pumps and consequently causes a de-priming of the pumps. Dry running is therefore not desirable. The pumping with "tarpaulins" guarantees the presence of liquid when the pumps are primed and therefore allows

  to avoid such dry running.

  However, the water present at the bottom of the tank, consciously

  due to the volume of ise charged, aga ga, such as for example methane and hydrogen sulfide. These gases cause the equipment to deteriorate, a risk of asphyxiation for personnel working in the tank, and a risk

  of explosion. [the waters present at the bottom of the tank favori-

  Also the proliferation of bacteria and the accumulation of

  we have sand and grease. Regular cleaning is therefore necessary to clean the pumping stations. The cleaning of pumping stations also includes the evacuation of the water present at the bottom of the tank, which therefore represents tedious work. In addition, the presence of water at the bottom

  of the tank does not allow Alectri-

in the tank.

  The operation by level detection is also troublesome when the level detection system is subject to a fault. The pump then continues to operate with an identical dAbit and ends up by priming. In other cases, the pump does not start, which causes an overflow

of the installation.

  In addition, this pumping "by bAchAs causes hydraulic slumps, in the networks and at the head of treatment stations, detrimental to the quality of the treatments. pollutants treated by intermittent spills due to these hydraulic discharges. Regular and constant spills were more favorable because too large or insufficient spills cause the destruction of the purifying microorganisms. Pumps must then be used

costly submersibles.

  It is an object of the present invention to provide an installation

  lation and a pumping device for pumping a

  liquid, without spilling the liquid at the bottom of the cove.

  It is another object of the invention to provide such a

  pumping device usable in renovation of installation

  faulty, capable of pumping liquid in a just-in-time fashion, and of operating in the absence of liquid arrival

without risk of defusing.

  To this end, the invention provides a device for pumping liquid, in particular for gravity networks, comprising a

  set of pumps having at least one pump. The device-

  is intended to be connected to a liquid network, in

  which the liquid height is variable, by a channel-

  clean intake to transmit the liquid from the network to the pumping device and through an outlet pipe suitable for transmitting the liquid from the pumping device to the network. The device also includes a main conduit

  connecting the pump assembly to the outlet pipe.

  Advantageously, the main conduit also directly connects the pump assembly to the inlet pipe, the main pipe being in sealed contact with the inlet pipe to receive the liquid arriving in the inlet pipe with a flow rate. given inlet and to transmit it continuously to the set of pumps, while the pumps of the set of pumps are designed to operate, whatever the flow rate of the liquid, in particular for a substantially zero flow rate , and to adjust their pumping flow according to the flow of arrival

some cash.

  According to another aspect of the invention, a pump of the pump assembly comprises a pump body consisting of a lower body and an upper body connected, the upper body

  being surmounted by an impeller driven by a motor.

  According to an essential characteristic of the invention, a pump of the pump assembly comprises a first connection duct connecting the lower pump body to an upstream part of the main duct, and a second connection duct connecting the upper pump body to a downstream part of the main duct, the upstream part of the main duct being connected to the inlet pipe and the downstream part of the main duct being linked to the outlet pipe. In particular, the first conduit is tangent to the lower pump body while the second conduit is tangent to the

upper pump body.

  The upper pump body is a hollow part, of circular horizontal section, intended to discharge the liquid to

  the second connection conduit, under the action of the impulse

  sor. The lower pump body is a hollow part, of circular horizontal section, intended to receive the liquid coming from the first connection conduit, this conformation of the lower pump body making it possible to create a rotation of the liquid having a speed linked to the flow rate of the liquid at

  the entry of the lower pump body.

  Advantageously, the upper pump body has a lower opening while the lower body has an upper opening, these openings being connected by a conical body, capable of discharging the liquid from the lower pump body to the upper pump body in operation. the speed of rotation of the liquid in the lower pump body, which allows the flow rate of all the pumps to be adjusted to the flow rate of the liquid in the

inlet pipe.

  The invention also provides a pumping installation, comprising a tank into which an inlet pipe and an outlet pipe opens, and a pumping device installed in the tank. Advantageously, the device

  pumping has one of the features described above

  before. The invention further covers a method of pumping liquid, arriving in an inlet pipe which opens onto a liquid network, in which the height of liquid is variable. The liquid is intended to be discharged to an outlet pipe connected to this network. According to an essential characteristic of the invention, pumping is

  carried out continuously and directly at the outlet of the pipe

  tion of arrival, whatever the flow rate of the liquid, in particular for a flow rate of substantially zero, while adjusting the pumping rate to the flow rate of the liquid. Other characteristics and advantages of the invention

  will appear on examination of the detailed description below,

  and annexed drawings in which: - the figure represents a pumping installation according to a first known embodiment, - figure lb represents a pumping installation according to a second known embodiment, - figure lc represents a pumping installation according to the invention , - Figure 2a is a diagram representing the height of liquid pumped into the tank as a function of time according to the first and the second known embodiment, i - Figure 2b "is a diagram representing the height of liquid pumped as a function of time according to the invention,

  - Figure 3 is a detailed representation of the installation

  tion according to the invention, - Figure 4 is a front view of the installation according to the invention, - Figure 5 is a top view of the installation according to the invention, - Figure 6 is a side view of the installation according to the invention, and - Figure 7 is a sectional view of the conical body

according to the invention.

  The drawings essentially contain elements of a certain character. They can therefore not only serve to

  make the description better understood, but also contribute

  to the definition of the invention, if applicable.

  In a known embodiment, represented in FIG. 1b, the pumps 50 vent placed at the bottom of the tank 10 and connected to an outlet pipe 201 by a main conduit 300. The water coming from an inlet pipe 20 is directly discharged at the bottom of the tank, the pumps being thus immersed, until they reach a predetermined height H. When this water level is reached,

  the pumps pump water.

  This level detection pumping is found in a previous embodiment. In this previous embodiment, illustrated in FIG. 1 a, the tank 1 has two parts 11 and 12. In the first part 11, the waters are poured out at the bottom of the tank up to a predetermined height H. When this height is reached, the water contained in the tank is transmitted by a conduit to the pumps 5 which are located in the second part 12 of the tank and proceed to pumping. The second part 12 of the tank is a dry pit, which means that the water circulates only in the piping. Figure 2a shows the height of the water pumped to the bottom of the tank as a function of time, in the two embodiments of the prior art. This diagram indicates more precisely that the installations treat a predetermined load volume, periodically. The period alone depends on the flow of incoming water. The invention provides an installation which allows continuous operation in just flow, without the presence of water at

bottom of the tank.

  FIG. 1c represents a pumping installation according to the invention. The tank 100 includes an inlet opening into which an inlet pipe 200 is introduced.

  conveying wastewater from a gravity network.

  The pumping installation according to the invention is suitable for pumping any liquid, possibly a body charge.

  solid and fibrous. The description will be made with reference to

  pumping of wastewater intended to be treated by a

  sewage treatment plant, by way of nonlimiting example.

  Advantageously, this inlet pipe is connected to an inlet valve 800 by a main conduit 300. The inlet valve is for example a commercial guillotine valve, mounted between flanges. The valve is connected to a set of pumps 500 by a part of the main conduit 300. Wile makes it possible to interrupt the flow of water to the pumps, for example in the event of personnel intervention for

maintenance.

  All of the pumps 500 are connected to an outlet pipe 2001, connected to the main conduit 300 at an opening in the tank. Between the pump set 500 and the outlet pipe, another valve 600 can be provided, fitted with a valve 700 to isolate the pump set from the outlet pipe and prevent any return.

of water in the pump set.

  The waste water arriving in the inlet pipe is poured directly and continuously into the main conduit 300 in the direction of the set of pumps. This installation

  therefore prevents the presence of liquid at the bottom of the tank.

  However, the invention includes other essential characteristics which make it possible, in addition, to compensate for regulation by level detection and dry operation.

  shoes. -They are detailed in the description below

after.

  Figure 3 is a detailed representation of the invention.

  In a preferred embodiment, the pump assembly 500 comprises two pumps 54 and 56, symmetrical with respect to the main conduit and each provided with a motor. These two pumps can operate simultaneously to increase the pumping rate. Wiles can also work

  independently of each other, especially in the event of a failure

spear from one of them.

  In the following, the description will be made with reference to a

  new installation according to the invention. The use of

  the invention under renovation will be discussed later. The disposi-

  pumping hose can be assembled before being installed in

tank 100.

  An adaptation piece 202, of the wall flange type, comprising an opening, is fixed to the wall of the tank to make contact between an upstream part 302 of the duct, generally leveled, and the inlet pipe 200. This piece d adaptation can adapt to any shape of tank. It can be a curved stainless steel plate with a flanged cuff. The seal between the adaptation piece 202 and the inlet pipe 200 is ensured by a seal, for example a

  flexible elastomer seal, not shown in the figure.

  The upstream part 302 of the conduit comprises the inlet valve 800, fixed by the flanges 802 and 803. The free end 2000 of the upstream part of the conduit is an auxiliary inlet, designed to receive water from another pipeline. arrival, not shown. The auxiliary input is notably

  planned for the renovation of faulty pumping installations

  lantes which have several inlet pipes.

  The auxiliary input allows vehicular, to the pumps, the

  waters which arrive by another arrival pipe.

  The upstream part of the duct is also connected, symmetrically, to the two pumps. Each pump is connected to the upstream part 302 of the conduit by a first connection conduit 314 (316) and to the downstream part (303) of the conduit by a second connection conduit 304 (306. More precisely, the second connection conduit is connected to a discharge manifold 600 which discharges the pumped water to the

exit.

  The upstream part of the main conduit also comprises a probe 804, placed at the outlet of the inlet valve, intended to measure the height of liquid in the upstream part of the conduit. This probe can be an analog pressure sensor, which transforms the height of liquid measured into an electrical signal, to transmit it to a cabinet.

regulation 904.

  This control box, supplied by known embodiments, allows regulation of the pumping device according to external conditions. It contains for example a circuit breaker, a programmable relay and 2 frequency converters allowing: - the reading of the liquid height in the upstream part of the duct, - the control of the pump flow by acting on variable speed drives coupled to the pumps. This external regulation system makes it possible to adjust the flow rate of the pumps to a desired output flow rate,

  - reversing or accelerating the direction of rotation of the pumps -

  pumping rate to get rid of an obstruction

  eventual tion, - the activation of the automatic back-up functions from one pump to the other, and the distribution of alternating running times, etc. This regulation box can be controlled remotely by a lat installation. i on such egest ion or directly by the information measured and transmitted by the probe. In particular, the probe is coupled to the speed controllers of the motors which then adapt the drive speed of the motors, and therefore the flow rate of the pumps, to the flow rate of the water entering the pumping device. This behind information is deduced from the information provided by the

measuring probe.

  This variable speed control of the motors reduces energy consumption to a strict minimum and promotes

  engine monitoring and longevity.

  The remote control, of the telegestion type, allows

  come remotely without dismantling and without stopping the device

pumping.

  We now refer to Figures 4, 5 and 6 which represent

  respectively try a front view, a top view and a

  side view of the pumping device according to the invention.

  A pump 54 (56) according to the invention comprises a motor 504 (506), for example a normalized asynchronous motor, supplied by a variable speed drive and a pump body. The motor is connected to a 524 impeller (526) via a drive wheel. The priming of the pumps takes place automatically as soon as the liquid / gas mixture reaches a sufficient density, thanks to degassing chambers, not shown, located behind

the impellers.

  A seal is placed between the motor and the impeller. Wile advantageously consists of sealing rings, for example lip rings, mounted in series to ensure the sealing of the pump body towards the outside, perpendicular to the impeller. This lip seal system allows operation at full load, but also the admission of large quantities of air and dry operation. It consists of simple and easy to replace parts. The seal of the invention does not require an oil chamber as in the

  known rotary systems which do not support a function-

  dry. In addition, the machining of parts is simple and inexpensive. The impeller rotates at a speed transmitted by the motor to impart a speed to the liquid flowing in an upper pump body 534 (536). For example, an impeller of the "built-in vortex" type is used which makes it possible to pump an air-water mixture and the passage of large solid bodies. It is in contact with the motor drive shaft and with the sealing rings. This arrangement eliminates the succession of spare parts of the systems

  known, in particular fragile mechanical seals.

  The upper pump body is connected to a lower pump body 554 (556) via a conically shaped body 544 (546). The upper pump body is also connected to the second connection duct 304 (306) and the lower pump body

  is connected to the first connection conduit 314 (316).

  Advantageously, the second connection duct 304 (306) is tangent to the upper pump body 534 (536) and the first connection duct 304 (306) is tangent to the body

of lower pump 314 (316).

  The upper pump body 534 (536) is a hollow cylindrical part, of circular horizontal section and has a lower opening to which is connected the smaller diameter end of the conical body, cited as the non-flared end. The lower pump body 554 (556) is a hollow boiler-like piece, of circular horizontal section and has an upper opening to which is connected the larger diameter end of the conical body,

cites flared end.

  Pump bodies 534, 536, 554, 556 and the conduits

  300, 302, 303 wind made of stainless materials.

  FIG. 3 also illustrates the progression of the water in the pumping installation. Flowing waters wind

  represented by arrows 102, 103, 104 and 105.

  The water to be lifted 102 arrives via the inlet pipe 200. Wiles arrive with a variable input flow over time. Wiles are then sent directly to the upstream part of the conduit. If the inlet valve 800 is open, they progress towards the first connection conduits 314 (316). These conduits bring the water 103 into the lower pump body 554 (556) or they are rotated. The shape of this body, its tangent connection with the first connection conduit and the speed of water arrival contribute to create this rotation. This rotational movement is all the more rapid as the speed of arrival of the waters is important. It recovers energy from the liquid

  which arrives in the lower body to accelerate it.

  This pre-rotation then allows the water to be sent to the upper pump body, via the conical body. The conical body 544 (546), shown in FIG. 7, concentrates the liquid in rotation towards the center of the upper pump body 554 (556). It allows on the one hand to connect the lower pump body 534 (536) to the upper pump body 554 (556) and on the other hand to print an upward movement to the waters present in the lower pump body, while accelerant. The speed of discharge of water from the lower pump body 534 (536) to the upper pump body 554 (556) depends on the speed of the pre

  rotation created, and therefore of the flow of water arrival.

  The diameter of the lower pump body 534 (536) is chosen to be greater than the diameter of the non-flared end of the conical body. The ratio of these two diameters is chosen according to the acceleration desired at the entry of the body.

upper pump.

  In the upper body 534 (536), shown in fig 3, the waters 104 are again rotated, due to the pre-rotation created in the lower body 554 (556) and the rotational movement transmitted by the impeller. The impeller is driven by the motor 504 (506) whose speed is adjusted according to the information from the probe 804. It creates a centrifugal force which pressurizes the liquid against the walls of the upper body and increases the speed of rotation

some cash.

  The speed of rotation of the liquid in the upper body is therefore obtained from a first form of regulation due to the pre-rotation in the lower body and from a second form of regulation due to the coupling of the probe and the variator. The first form of regulation allows the flow of incoming water to be regulated by using the energy it transports. The second form of regulation makes it possible to regulate the flow of water leaving the pumps. These two forms of regulation help to serve the pump flow to the incoming water flow and to external pumping needs. The speed obtained in the upper pump body makes it possible to create a pressure at the inlet of the discharge manifold 508 and therefore to discharge the water 105 towards the outlet pipe. The pumping installation is therefore capable of absorbing in a just-in-time manner the variable flow rate of a gravity network loaded with solid or fibrous bodies, without requiring any loading volume. Figure 2b shows the height of treated water

  by an installation according to the invention, as a function of time.

  This diagram, presented as an example, shows that the pumps operate continuously on a load volume

variable.

  In addition, the absence of loading volume makes it possible to limit the dimensions of the tank to the size of the device. Consequently, the tanks of the new installations according to the invention may have smaller dimensions.

to the tanks of prior art.

  The absence of water at the bottom of the tank facilitates intervention.

  staff. In addition, it makes it possible to arrange the

  room, by placing, for example, the 'direct electrical cabinet-

lying in the tank.

  The dry installation of the pumping device in the installation and its simple construction improve the maintenance of works and equipment, by proposing a material placed in a dry pit and which can be easily isolated from the inlet and outlet pipes. The installation also allows control of the flows actually collected and vehicles. Billing to communities and manufacturers of treated effluents is

therefore better controlled.

  The just-flow pumping of charged effluents, comprising fibers or papers is no longer disturbed by an obstruction of the inlet pipe as is

was producing in prior art.

  In addition, the pumping device can be used

  to renovate failed art installations

  or facilities according to the invention.

  The pumping device described above is used, choosing a range of flow rates for the set of pumps, adapted to the space available in the tank of the installation to be renovated and to the electrical power available on the

site.

  In the case of the renovation of an art installation

  earlier, there is no need to empty the water present

your at the bottom of the tank.

  The pumping device according to the invention adapts to

  different types of effluents and different shapes of tank.

  An inflatable tube is placed beforehand in the inlet pipe to cut off the arrival of water while the pumping device is attached. The pumping device

  the defaulter is then removed for service.

  The adaptation to the inlet pipe is notably carried out by an adaptation piece 202. After having fixed the adaptation piece 202 on the wall of the tank, the pumping device is then fixed by flanges in the cove of the 'faulty installation, at the inlet pipe and the outlet pipe. We then withdraw

  the inflatable tube of the inlet pipe. The adaptation to the outlet pipe is achieved by a set of

  parts which replace existing valves of

the installation to be renovated.

  The control box used in the invention is supplied in a transportable waterproof case for renovation. It can be connected to any electrical cabinet tail and be

  fixed at any point in the tank.

  The electric cables of the motors and of the probe provided by the invention are fitted with withdrawable plugs and are fitted with wind.

  protected by a flexible umbilical conduit.

  The installed pumping device then treats the incoming water, as described above, while eliminating level problems, until the installation

failing to be renovated.

  The installation of the pumping device according to the invention in a faulty pumping installation is therefore simple and rapid, which avoids polluting spills in the environment. The invention has been described with reference to an installation comprising a tank for pumping wastewater intended to be treated by a treatment plant, not

  limiting. Other installations and applications of the device

  tif pumping can be considered.

  The device of the invention can, for example, be used to maintain the level of a basin receiving water from a

  waterfall, to regulate the storm basins or to freeze

  chir the construction of a loading basin. It can still be used for a common regulation of

  back-ups from several pumping stations.

  The invention is not limited to a set of pumps either.

  including two pumps. For particular applications-

  demanding in terms of flow or safety, it is possible to use several pumps and preferably several

couples of pumps in eerie.

  In addition, it is possible to envisage connecting the lower pump body to an under-draft valve to recover the solids present in the liquid. The rotation of the

  fluid in the lower body indeed promotes an under-

  pulling of suspended solids which concentrate in the middle

from the body.

Claims (18)

claims   1. Liquid pumping device, in particular for gravity network, comprising a set of pumps (500) having at least one pump, the device being intended to be connected to a liquid network, in which the height of liquid is variable, by an inlet pipe (200) suitable for transmitting the liquid from the network to the pumping device and by an outlet pipe (2001) suitable for transmitting the liquid from the pumping device to the network, the device comprising a main conduit (300) connecting ['set of pumps to the outlet pipe, characterized in that the main duct (300) also directly connected [' set of pumps to the inlet pipe (200), the main pipe being in tight contact with the inlet pipe to receive the liquid arriving in the inlet pipe with a flow rate   of given arrival and to transmit it continuously to the whole   ble of pumps (500), and in that the pumps of the set of pumps are designed to operate, whatever the flow rate of the liquid, in particular for a substantially zero flow rate of arrival, and to adjust their flow rate pumping in   function of the liquid arrival flow.   2. A pumping device according to claim 1, characterized in that a pump of the pump assembly comprises a pump body consisting of a lower pump body (554,556) and an upper pump body (534,536 ) connected, the upper pump body (534,536) being surmounted by a   impeller (524) driven by a motor (504,506).   3. Pumping device according to claim 1, characterized in that a pump ['pump assembly comprises rings (514,516) mounted in eerie, placed between the motor and the impeller, which guarantees the tightness of the pump body and allows the pump to operate at a flow rate   substantially zero liquid arrival.   4. Pumping device according to claim 1, characterized in that ['the pump assembly comprises a valve (800), said inlet valve, suitable for stopping the evolution of the liquid coming from the inlet pipe to [ set of pumps. 5. Pumping device according to claim 1, characterized in that the pump assembly comprises two pumps (54, 56), symmetrical with respect to the main duct,   able to operate independently of each other.   6. Pumping device according to one of the preceding claims   tes, characterized in that a pump of the pump assembly comprises a first connection duct (314,316) connecting the lower pump body to an upstream part (302) of the main duct, and a second connection duct (304,306) connecting the upper pump body (514, 516) to a downstream part (303) of the main pipe, the upstream part of the main pipe being linked to the inlet pipe and the downstream part of the main pipe being linked to the pipe of exit.   7.Pumping device according to claim 6, characterized in that the first conduit (314,316) is tangent to the lower pump body (554, 556-) and in that the second conduit   (304,306) is tangent to the upper pump body (534,536).   8.Pumping device according to claim 6, characterized in that the upper pump body (534,536) is a hollow part, of circular horizontal section, intended to discharge the liquid towards the second connection conduit   (304,306), under the action of the impeller (524).   9. Pumping device according to claim 6, characterized in that the lower pump body (554,556) is a hollow part, of circular horizontal section, intended to receive the liquid coming from the first connection conduit (314,316), this conformation of the lower pump body making it possible to create a rotation of the liquid (103) having a speed linked to the flow rate of the liquid at the inlet of the pump body lower (554,556).   10. Device according to claim 8 taken in combination with claim 9, characterized in that the upper pump body has a lower opening and in that the lower body has an upper opening, these openings being connected by a body of conical shape (546), capable of pumping the liquid from the lower pump body (554,556) to the upper pump body (534,536) as a function of the speed of rotation of the liquid in the lower pump body, which makes it possible to adjust the flow rate of the set of pumps at the flow rate of the liquid in the inlet pipe.   11. Device according to claim 10, characterized in that the larger diameter end of the conical shape body, cited flared end, is connected to the lower pump body (534,536) and in that the diameter of the end not - flared body of conical shape is less than   diameter of the lower pump body (534,536).   12. Pumping device according to claim 1, characterized in that the main conduit comprises an auxiliary liquid inlet (2000), intended to be connected to a second inlet pipe.   13. Pumping device according to claim 7 taken in combination with claim 5, characterized in that the inlet valve (800) is placed on the upstream part of the main duct.   14. Pumping device according to one of claims   previous, characterized in that the conduits (300,302, 303), the lower pump body and the upper pump body (534,536,554,556) are made from stainless materials.   15. Pumping device according to one of claims   previous, characterized in that it comprises a sensor (804) for measuring a value relating to the flow rate of the liquid. 16.Pumping device according to claim 15, characterized in that it comprises a variable speed drive (904) coupled to the pump assembly and connected to the sensor (804) for measuring the flow rate of the liquid, capable of '' adjust the flow rate of the set of pumps to the value measured by the sensor.   17. Pumping device according to one of claims   previous, characterized in that it includes a remote control system capable of acting on the speed variator speed (904).   18. Pumping installation, comprising a tank (100) into which an inlet pipe (200) and an outlet pipe (2001) open, and a pumping device installed in the tank, characterized in that the device   pumping is as described in one of the claims   preceding. l9. Liquid pumping process, arriving in an inlet pipe (200) which leads to a liquid network, in which the height of liquid is variable, and intended to be discharged towards an outlet pipe (2001) connected to this reseal, characterized in that the pumping is carried out continuously and directly at the outlet of the inlet canalization, whatever the flow rate of the liquid, in particular for a substantially nut flow rate, and in that one adjusts the pumping flow to the flow of arrival of the