FR2668187A1 - WC system operating by suction and using a treated rinsing liquid, and method for operating such a system - Google Patents

Abstract

The invention relates to a WC system operating by suction and using a treated rinsing liquid, and to a method for operating such a system. The performance of a WC system for a transportation vehicle, in which the waste substances are deposited in a bowl (64) and are evacuated by flushing with a rinsing liquid driven by suction into a discharge channel is improved by adding a metered quantity of reagent, taken from a container (74), to the rinsing liquid, taken from another container (68), in order to improve the evacuation by flushing and to act on the waste substances removed. Application in particular to the WC systems operating by suction and used in trains and aircraft.

Description

 The present invention relates to a W.C.

vacuum operated with a treated flushing liquid, a method for operating such a
WC and a method for improving the operating efficiency of a transport vehicle having a
Vacuum WC, in which rinsing is carried out.

 A non-recirculating vacuum WC system, which uses ordinary water as a flushing liquid is advantageous for its use in a transport vehicle. In such a system, it is conventional for the flushing liquid to be delivered from the vehicle's drinking water system. The drinking water system includes a tank, pipes connecting the tank to user devices such as vacuum toilets and sinks, and a pump to keep water under pressure in the pipes.

 A known vacuum WC system suitable for use in a vehicle such as a train or an airplane, comprises a bowl for receiving the excrement, a drain pipe which can be subjected to a pressure much lower than that present at the inside the bowl for receiving the droppings, and an evacuation valve used to control the passage of the droppings from the bowl, which receives them, in the direction of the drainage pipe. A spray ring can be arranged around the rim of the bowl receiving the droppings and this ring can be equipped with nozzles which are arranged so that the entire internal surface of the bowl is rinsed when the spray ring is supplied in water from the vehicle's drinking water system.

 The supply of water to the spray ring must be controlled by a rinse water control valve, which can operate in response to an electrical signal which is produced by a wash down control unit. , when the latter receives an evacuation trigger signal by washing. A pressure relief switch can be connected between the rinse water control valve and the spray ring.

A disadvantage of this known type of system
Vacuum WC is linked to the fact that a small amount of water remains in the flushing water supply line downstream of the pressure relief switch, when the water control valve rinsing closes, and this water exits through the spray water nozzles between the washing discharge operations.

Part of this water evaporates and calcium carbonate dissolved in the water is deposited in the toilet bowl.

and in the nozzles themselves. This is why the surface of the toilet bowl becomes rough and the nozzles are partially blocked. The roughness of the toilet bowl surface reduces the efficiency with which droppings are removed during the washing process, and even partial obstruction of the nozzles changes the spray pattern provided by the nozzles and affects the flushing function.

 The problem of calcium carbonate formation is at least partially avoided in the vacuum WC system described in EP-A-0363012, since in this WC system no water remains in the supply line of the rinsing water after evacuation by washing is complete.

 In an airplane vacuum system, the supply of drinking water is strictly limited and that is why a very small quantity of rinsing liquid is available for each evacuation by washing, although a very large volume of air passes through the system during each evacuation by washing. Taken in combination, these two factors lead to the formation of a residue or a hard plate on the interior surfaces of the drain pipe and the holding tank. It is possible to remove the residue by periodically cleaning the pipeline with acid, but safety factors preclude the use of acids on board an aircraft. In addition, depositing droppings on level sensors in the tank can affect the accuracy of the level sensors.

 It is known to introduce a chemical reagent into the rinsing water of a conventional flush toilet to carry out hygienic cleaning of the toilet bowl during each evacuation by washing. This can be achieved by hanging a pad of water soluble material in the wash water tank. However, to the knowledge of the applicant, a similar technique has never been applied to a vacuum WC system and in particular by a vacuum WC system intended for use in a vehicle. This may be due to the fact that, in accordance with current practice, an electric pump is necessary to introduce the chemical reagent into the flushing liquid of a vacuum WC system and this requires an additional electrical outlet. an additional electrical outlet is a particular drawback when transforming a toilet system

with vacuum existing by equipping it with a pump for the introduction of the reagent. In addition, the electric pump must be controlled and this implies that the wash evacuation control unit is modified and that it is necessary to install control conductors between the wash control unit and the pump.

 A vacuum WC system installed in an airplane or train includes a holding tank used to receive the droppings. In accordance with standard practice, a bactericide preload is placed in the holding tank in order to treat the excrement which is collected in the holding tank. A large aircraft such as the Boeing 747-400, for example, could include four independent vacuum WC systems, each with a holding tank, the total mass of the preload possibly exceeding 75 kg.

 It has been found that a plate forms on the rotary disc of the vacuum valve of the vacuum toilet, shown in US-A-4 713 847. This is probably due to the fact that droppings enter the valve housing when the hole in the disc passes in front of the sealing elements, and the high concentration of salts in the droppings inside the valve housing leads to a deposit on the disc. The plate increases the drag applied to the disc and therefore the current required to drive the valve increases as well as the time required for the disc to rotate to come into its final position. This situation increases the risk of a valve malfunction.

According to a first aspect of the invention, a vacuum toilet system comprises a bowl
WC having an outlet opening for manure, a drain pipe having an interior space intended to receive manure and ending at least in a holding tank, an evacuation valve connecting the outlet opening of the toilet bowl to the drain line, a source of partial vacuum for establishing a significantly lower pressure in the interior space of the drain line than in the toilet bowl, which creates a pressure difference of sufficient value to carry out an effective entrainment of the waste water in the drain pipe, means defining an outlet for the flushing liquid, making it possible to introduce a flushing liquid into the toilet bowl for washing the latter, means for sending the flushing liquid rinsing at the outlet of the rinsing liquid, a container for reagent, placed in communication with the outlet for the rinsing liquid, the reagent placed in the container being chosen so as to improve the evacuation by washing and acting on the excreta evacuated by washing, in the at least one holding tank, and means for introducing a selected volume of the reagent from the container into the toilet bowl by intermediate the outlet of the rinsing liquid during each evacuation operation by washing, the additions of the reagent in the at least one holding tank taking place in an incremental manner and associated with the use of the system.

 According to another aspect of the invention, there is provided a method for operating a W.C.

vacuum, which comprises a toilet bowl having an outlet opening for manure, a drain pipe having an interior space, a discharge valve connecting the outlet opening of the toilet bowl to the drain pipe, a source of partial vacuum for the establishment of a clearly lower pressure in the interior space of the drain pipe than in the toilet bowl and sufficient to carry out a drive of the excretions from the toilet bowl in said interior space, means defining an outlet for the flushing liquid for introducing a flushing liquid into the toilet bowl for washing the toilet, and a source of flushing liquid, said method comprising sending the flushing liquid from the source to the outlet of the liquid rinse, add a selected volume of reagent to the rinse aid supplied by the rinse aid source, and introduce the liquid e of rinsing and the reagent in the toilet bowl by means of the outlet of the rinsing liquid, the reagent being chosen so as to improve the evacuation by washing and to act on the excretions located in the drain pipe.

 According to a third aspect of the invention, a method for improving the operating efficiency of an aircraft comprising a vacuum WC system comprising at least one flushed WC bowl, is characterized in that a metered amount of bactericide is added to the rinse water sent to the toilet bowl (s)

Other characteristics and advantages of the present invention will emerge from the description given below taken with reference to the appended drawings, in which
- Figure 1 schematically shows a first vacuum WC system according to the present invention; and
- Figure 2 schematically shows a second vacuum WC system according to the present invention.

 The invention is particularly suitable for use in planes or trains (for example the TGV - high speed train), but, for convenience, the description which follows mentions only the use in an airplane since this mode of use includes certain specific aspects which are not necessarily required on a train.

Figure 1 schematically illustrates how a liquid reagent can be introduced into a flow of pressurized flushing liquid in a vacuum toilet system of the type known in US-A-4 713 847. The system shown comprises a device vacuum switch and a solenoid valve 2, integrated, of the type described in
US-A-4 811 754 and which has an inlet connected to a pressurized rinsing water supply and an outlet connected via a rinsing water supply pipe 4, to a projection ring 6 This system also includes a pump 10 actuated by pressure, which comprises a housing defining cylinders 14,16 having a large diameter and a small diameter, and pistons 20,22 respectively housed in the cylinders, these elements delimiting two chambers variable volume 17.18 having different diameters. The two pistons are rigidly connected together so as to form a unitary piston element. A pressure spring 26 pushes the piston element back into the position in which the volume of the chamber 17 of large diameter is minimum.

 The large diameter chamber 17 is an actuation chamber and is connected to a branch of the rinsing water supply pipe 4. A container 30 or a liquid reagent is equipped with a submerged tube 34, which is connected , by a non-return valve 36 and a throttled passage 38, to the small-diameter pumping chamber 18 of the pump 10, and is also equipped with an aeration tube 40. The connection point of the non-return valve 36 and the throttled passage 38 is connected by means of a second non-return valve 44 to the pipe 4 for supplying the rinsing water.

 When the valve 2 for rinsing water supply is open so that the pressurized water is sent into the line 4 for supplying the rinsing water, the pressure in this line increases and consequently the piston element 20/22 is moved against the force of the compression spring 26, in a direction leading to a reduction in the volume of the pumping chamber 18. The fluid present in the pumping chamber is discharged through the passage 38 and the second non-return valve 44, and enters the line 4 for supplying rinsing water. When the valve 2 for supplying the rinsing water closes, the compression spring 26 must again move the piston element 20/22 in a direction such that the volume of the actuation chamber 17 is reduced. The pressure in the pumping chamber 18 decreases and the non-return valve 44 prevents this pressure difference from being reduced by an entry of fluid from the line 4 for supplying the rinsing water.

In this way, the liquid reagent is withdrawn from the container 30 to be introduced into the pumping chamber 18.

The next time the rinse water supply valve 2 is open and the piston element 20/22 is moved against the force of the compression spring 26, the liquid reagent located in the chamber pumping 18 is discharged through the passage 38 of the non-return valve 44 inside the pipe 4 for supplying rinsing water. This is why, each time the valve 2 for supplying the rinsing water is open, a measured dose of the liquid reagent is introduced into the supply line for the rinsing water. Since the pump 10 is actuated by pressure, it is not necessary to provide an additional electrical outlet or control conductors, and this facilitates the adaptation of an existing vacuum WC system, by means of mounting 'a pump 10 and a container 30 on this system.

The passage 38 is dimensioned so that the stroke of the pump is basically carried out with a duration identical to that of the washing and rinsing cycle, so that the liquid reagent is sent during the washing and rinsing cycle and is diluted substantially uniformly before being sprayed onto the surfaces of the
WC

 The liquid reagent present in the container 30 preferably comprises an aqueous mixture formed of four main components miscible with water. It is desirable that these components be a bactericide, a surfactant, an agent to inhibit the precipitation of calcium carbonate and an agent for dissolving existing deposits of calcium carbonate. The mixture of components must be as concentrated as possible (in particular in the case of an airplane) provided that it is not too concentrated to the point that phase separation in the mixture occurs, which would cause the rinse water would not receive the expected amounts of the components of the mixture.

 The bactericide is the most important component of the liquid reagent since it acts against the bacteria present in the droppings. If a sufficient amount of bactericide is present in the holding tank, personnel responsible for emptying the tank and / or disposing of its contents may be exposed to the danger presented by live bacteria. The use of an appropriate load of bactericide in the liquid reagent avoids the need to put a preload of bactericide in the or each droppings container and ensures that the amount of bactericide, which is used, is always closely associated with the quantity required. The preferred bactericide is a quaternary amine, namely the same amine as the "quaternary ammonium compound". A modern airplane vacuum toilet system uses approximately 0.2 liters of water during each flush, and the volume of water is typically about 0.25 liters during each wash. To be effective, and it is essential that the bactericide is effective, the quaternary amine must be present in the waste water (excreta plus rinse water) in a concentration in the range between about 600 ppm and about 800 ppm. A correct dose of bactericide can be obtained by introducing the quaternary amine into the aqueous mixture of the constituents, in a concentration equal to about fifteen percent by volume and by introducing a dose of 1.5 ml of the mixture during each evacuation by washing. .

 At a concentration of fifteen percent by volume, the quaternary amine is considered non-hazardous. When the plane lands, it is preferable to evacuate the contents of the or each holding tank in a municipal sewer. Quaternary amines are non-toxic and biodegradable and that is why the wastewater present in the tank and treated with this biocide can be discharged into a municipal sewer without additional treatment.

 The preferred surfactant is an amphoteric surfactant, preferably ethoxylated alcohol, which slowly forms a foam, is not ionic and is biodegradable. The role of the surfactant is to prevent precipitation of solids on the interior surfaces of the drain lines and the holding tank by an emulsifying action which keeps the solids in suspension.

The surfactant also improves the wetting of the interior surfaces of the holding tank and the pipes and thus facilitates the removal of any plaque-shaped deposits which have formed before. In addition, the surfactant improves cleaning of the bowl.
WC Suitably, the concentration of amphoteric surfactant derivatives in the liquid reagent is about twenty percent by volume.

 The preferred anti-precipitation agent is sodium phosphonate, which forms complex ions with calcium and thereby increases the threshold concentration for the calcium precipitate. The preferred concentration of sodium phosphonate in the liquid reagent is about twenty percent by volume.

 The agent, which is used to dissolve precipitates of calcium carbonate that have already formed, appropriately imparts a pH of less than 7 to the reagent.

Suitably, acetic acid is present in the liquid reagent in a concentration of about five percent by volume. A preferred pH of the liquid reagent is approximately 5.2.

 In addition to the four main components previously mentioned, coloring agents and deodorants can be inserted into the liquid reagent, typically in a concentration of less than about one percent by volume.

 Surprisingly, we have found that adding a chemical reagent (such as a reagent indicated above in detail) to the flushing liquid of an airplane vacuum WC system rather than pretreating the or the aircraft's wastewater holding tanks with a biocide, can lead to an improvement in the aircraft's operating performance. This is due in part to the small reduction in the tare weight of the aircraft and in part to a reduction in the amount of chemicals required. One liter of liquid reagent is sufficient for approximately seven hundred evacuations per wash, and depending on the use of the WC, this extends over a period of at least fifty hours of flight.A liter of liquid reagent has a mass d about 1.02 kg, so that the average mass of the reagent, if it is assumed that it is present when the reagent is half full, is equal to 0.51 kg. The container itself and the pump have a mass of approximately 1.4 kg. Consequently, the total mass is equal to approximately 1.9 kg per WC In the case of a boeing 747-400 having fourteen WCs, the total mass is 26.6 kg, which leads to a reduction of approximately 50 kg compared to the use of a bactericide preload.

 The vacuum WC system shown in Figure 2 is similar to that described in Figures 5 and 6 of EP-A-0363012. In the context of the present invention, it suffices to mention that, when a cover 60 of a WC bowl 64 is closed and a discharge valve 62 connecting the bowl to a vacuum emptying system is open, a partial vacuum is established inside the space of the bowl 64 due to a system sealing the lid placed above the cup. This depression entrains the raw water which has accumulated before in a reservoir 68 (for example from sinks such as that shown in 50), by means of a conduit 66 for supplying rinsing water to a pipe 70 for distributing rinsing water , so that this water is evacuated in the toilet bowl by performing an evacuation by washing and rinsing each time the valve 62 is opened while the cover 60 is closed.

 The system shown in Figure 2 includes a container 74 containing the liquid reagent. A submerged tube 76 is connected to the conduit 66 for supplying the rinsing water and extends downwards near the bottom of the container, where it is equipped with a non-return valve 80. The container 74 has an opening d ventilation 78 at its upper part.

When a pressure lower than the ambient pressure is established in the conduit 66 for supplying the rinsing water during an evacuation operation by washing, a charge of the liquid reagent is entrained from the container 74 and is introduced into the flow of rinse water entering the line 70. When the reagent rinse water, which has been added, enters the cuvette
WC, air is mixed with the liquid and the presence of a surfactant and a bactericide in the reagent results in the formation of an antiseptic foam.

 The valve 62 is a rotary disc valve of the type described in US-A-4 713 847. A tube 82 shown connected between the conduit 66 and the valve housing 62 can be used to evacuate part of the rinsing liquid and the reagent, which is added to it, in the valve, and prevent the formation of calcium deposits and a plaque in the valve, in particular on the disc of the latter. Injecting a rinse aid into the valve housing reduces the amount of waste water that can enter the valve housing and dilutes the salt concentration of the waste water entering the valve housing. In addition, the rinse aid rinses out the wastewater by sending it to the drain system. In this way, the operating life of the valve is increased. In addition, the preferred composition, described above, of the liquid reagent has a lubricating effect, which makes it possible to relearn the drag on the disc, while reducing the energy (eg electric current) required to rotate the disc and while reducing the time required for the disc to rotate between end positions. This is why the risk of a malfunction is reduced.

 The system shown in Figure 2 operates by automatically adding a reagent to the rinse aid, in metered amounts related to the flow of rinse aid to the bowl 64 (and therefore operating in a functional relationship related to the flow of rinse aid) without the use of a pump currently driving the reagent.

 FIG. 2 also schematically represents a switch 51 for initiating the evacuation by washing for actuating the valve 62 by means of a unit 52 for controlling the evacuation by washing, which can also be used to control a valve 53 sending water to the bowl 50.

 It should be noted that the invention is not limited to the particular embodiments which have been described and that modifications can be made thereto without departing from the scope of the invention. For example, the embodiment shown in Figure 1 is not limited to a pump having a movable piston, since an injector pump can be used to introduce a liquid reagent into the supply line of the rinse water.

Claims (23)

 1. Vacuum WC system, characterized in that it comprises  (a) a toilet bowl (64) having an outlet opening for excrement,  (b) a drain pipe having an interior space intended to receive the excrements and ending at least in a holding tank,  (c) a drain valve connecting the outlet opening of the toilet bowl to the drain pipe,  (d) a source of partial vacuum for establishing a significantly lower pressure in the interior space of the drainage pipe than in the toilet bowl, which creates a pressure difference of a value sufficient to achieve efficient entrainment of wastewater in the drain pipe,  (e) means (6 ;; 70) defining an outlet for the rinsing liquid, making it possible to introduce a rinsing liquid into the toilet bowl for washing the latter,  (f) means (2.10) for sending the rinse aid to the outlet of the rinse aid,  (g) a receptacle (30; 74) for reagent, placed in communication with the outlet for the rinsing liquid,  (h) the reagent placed in the container (30; 74) being chosen so as to improve the evacuation by washing and to act on the excreta evacuated by washing, in the at least one holding tank, and  (i) means for introducing a selected volume of the reagent from the container into the toilet bowl (64) by means of the outlet for the flushing liquid during each evacuation operation by washing, the additions of the reagent in the minus a holding tank which is performed incrementally and associated with the use of the system.  2. Vacuum WC system according to claim 1, characterized in that the means (2.10) for sending the flushing liquid comprise a first pump (10) serving to send a flushing liquid under pressure and a valve (2 ) mounted between the pump and the rinse aid outlet, and the introduction means comprise a second pump for adding the reagent from the container to the rinse aid between the valve and the outlet for the rinse aid.  3. Vacuum WC system according to claim 2, characterized in that it comprises a pipe for supplying the flushing liquid mounted between the valve (2) and the outlet for the flushing liquid (6; 70), and that the second pump is a pump actuated by a pressure and which responds to the pressure prevailing in the line for rinsing liquid to add said reagent from the container to the rinsing liquid located in the line for rinsing liquid when the valve is open.  4. Vacuum WC system according to claim 1, characterized in that the introduction means comprise means for adding a metered quantity of liquid reagent to the flow of rinse liquid sent to the outlet of the rinse liquid, the metering means operating each time supply means send rinse aid to the outlet of the rinse aid.  5. Vacuum WC system according to claim 1, characterized in that the WC bowl (64) has a rim, the outlet for the flushing liquid is arranged so as to introduce the flushing liquid into the WC bowl when a lid (60) of the bowl is in a closed position relative to the rim, whereby the flushing liquid and the reagent are drawn from a source of flushing liquid and from the container, respectively, into the toilet bowl through the via the outlet for the flushing liquid (70), when the drain valve is open and the cover is in the closed position.  6. Vacuum WC system according to claim 5, characterized in that it further comprises a reservoir (74) having an inlet opening intended to receive the flushing liquid from a source of the flushing liquid ( 68), and an outlet opening in communication with the outlet of the rinsing liquid, the inlet opening of the reservoir being subjected to substantially the same pressure as the outlet of the rinsing liquid when the cover is in the open position and the discharge valve is in the closed position, the flushing liquid and the liquid reagent being entrained respectively from the reservoir (74) and the container (68), into the toilet bowl via the liquid outlet when the drain valve is open and the cover is in the closed position.  7. Vacuum WC system according to any one of claims 1 to 6, characterized in that a housing of the discharge valve is connected to a conduit extending between the pipe for supplying the flushing liquid and the valve housing for the introduction of the rinsing liquid into this housing.  8. Method for operating a Vacuum toilet, which includes a toilet bowl (64) having an outlet opening for excrement, a drain pipe having an interior space, a discharge valve connecting the outlet opening of the toilet bowl to the pipe a partial vacuum source for the establishment of a significantly lower pressure in the interior space of the drain pipe than in the toilet bowl and sufficient to carry out a drive of the droppings from the toilet bowl W.C. in said interior space, means defining an outlet for the rinsing liquid for introducing a rinsing liquid into the toilet bowl for washing the latter, and a source of rinsing liquid, characterized in that it consists of  (a) send the rinsing liquid from the source to the outlet of the rinsing liquid,  (b) adding a selected volume of reagent to the rinse aid supplied by the source of rinse aid, and  (c) introducing the flushing liquid and the reagent into the toilet bowl by means of the outlet of the flushing liquid, the reagent being chosen so as to improve the evacuation by washing and to act on the excretions situated in the drain pipe. emptying.  9. Method according to claim 8, characterized in that step (b) comprises the addition of a reagent which contains at least two of the following products, namely a bactericide, a surfactant, an agent inhibiting the formation of calcium carbonate deposits and an agent which removes existing calcium carbonate deposits.  10. Method according to claim 9, characterized in that the volume of the reagent added to the rinsing liquid during each evacuation by washing is of the order of 1.5 ml.  11. Method according to any one of claims 8 to 10, characterized in that step (b) comprises the addition of a liquid reagent which contains a quaternary amine.  12. Method according to claim 11, characterized in that the concentration of the quaternary amine in the droppings plus the rinsing liquid is in the range from 600 ppm to 800 ppm.  13. The method of claim 12, characterized in that the concentration of the quaternary amine in the holding tank supplied from the drain does not exceed 15 percent.  14. Method according to any one of claims 8 to 13, characterized in that step (b) comprises the addition of a liquid reagent including a surfactant.  15. The method of claim 14, characterized in that the surfactant occupies 20 percent of the volume of the reagent.  16. Method according to one of claims 14 or 15, characterized in that the surfactant is an amphoteric surfactant derivative.  17. Method according to any one of claims 8 to 16, characterized in that step (b) comprises the addition of a liquid reagent which includes a composition forming complex ions with calcium.  18. The method of claim 17, characterized in that said composition is sodium phosphonate.  19. The method of claim 18, characterized in that the concentration of sodium phosphonate occupies 20 percent of the volume of the reagent.  20. Method according to any one of claims 8 to 19, characterized in that step (b) comprises the addition of a liquid reagent with a pH below 7.  21. The method of claim 20, characterized in that 5 percent of the volume of the reagent is formed by acetic acid.  22. Method according to any one of claims 8 to 21, characterized in that the pH of the reagent is approximately 5.2.  23. The method of claim 8, for improving the operating efficiency of an aircraft comprising a vacuum WC system comprising at least one flushed WC bowl (64), characterized in that a metered amount of bactericide is added to rinse water sent to the toilet bowl (s)