EP0258525A2 - Vacuum dewatering installation - Google Patents

Abstract

1. A vacuum drainage installation having one or more collection tanks in which an underpressure prevails and to which are connected vacuum conduits (10) which are laid alternately ascending and descending and to which connecting ducts of the units to be drained are connected via a respective extraction valve, normal pressure prevailing in said connecting ducts, which extraction valve is opened automatically when a given amount of water of from 5 to 40 litres has accumulated upstream thereof, and which during each opening operation admits air together with the waste water into the vacuum conduit (10), wherein at least one venting aperture (34), which is controlled by a control device as a function of the water level or pressure at a given location of the vacuum conduit (10), is provided in the vacuum conduit (10), characterised in that the aperture width of the venting aperture (34) can be controlled continuously or in a plurality of stages within a range in which such small quantities of air are admitted that said air bubbles through water columns present in the vacuum conduit (10).

Description

The invention relates to a vacuum drainage system with one or more vacuum tanks and connected to it, alternatingly rising and laid vacuum lines, to which are connected to normal pressure connecting lines of the units to be dewatered via a suction valve, which opens automatically when a certain amount of wastewater of about 5 to 40 liters has accumulated in front of it, and with each opening process, together with the wastewater, lets air into the vacuum line, at least one ventilation opening on the vacuum line being controlled by a control device depending on the water level or pressure at a specific point on the vacuum line Vacuum line is arranged.

Such a vacuum drainage system is known from DE-OS 26 37 962. It works on the principle of letting as little air as possible into the vacuum line during times of normal operation, and in quiet times when the air flowing in together with a portion of waste water when opening a suction valve is no longer sufficient to transport the water, i.e. in form long water columns in the Line remains, through which the air just bubbles through, to open ventilation devices that suddenly let in a lot of air. The ventilation devices remain open until the water columns in the vacuum line have at least been transported over the next slope or until the line is completely empty, which can result in opening times of more than 30 minutes.

The known device has not proven itself in practice because the condition conditions in the vacuum line are too different when the ventilation devices are closed or open. Since the intermittent intake of large amounts of air is an extreme measure, it is only used when the filling of the vacuum line with waste water has already reached an advanced stage in which the so-called simultaneity factor, i.e. a coincidence of the opening processes of several suction valves, no longer applies could help. However, the poor pressure conditions in the largely filled line do not change immediately even if the ventilation devices suddenly take in a lot of air. Since the existing large water columns start to move only slowly, the vacuum now collapses even more, there are malfunctions in the suction valves that are automatically operated with the system vacuum, and the vacuum pumps take a long time to process not only the accumulated water but also the water have sucked in any additional large amounts of air. If the ventilation devices are located in the middle area of vacuum lines, the vacuum reservoir in the outer line part also has an effect such that the suddenly flowing air drives the water in the wrong direction. Finally, the known drainage system also does not work particularly economically, since with longer, standing water columns that can only be accelerated slowly, a considerable part of the amount of air entering through the ventilation devices and the house connections bubbles through without to be able to contribute a lot to the acceleration or possibly even to the movement of the water columns.

From US Pat. No. 3,730,884, it is also known to mount adjustable ventilation devices at the end of vacuum lines which, according to the respective setting, allow a constant, very small amount of air to flow in via a screw thread in order to constantly aerate the waste water and thereby prevent decay . However, the small amounts of air set to a constant value cannot contribute to the wastewater transport and its automatic control, since in this known system the wastewater amounts let into the vacuum line when a shut-off valve is opened are very large at around 400 liters and form very long water columns from the outset.

The invention has for its object to provide a vacuum drainage system of the type mentioned, in which the wastewater volume is constantly delicately influenced, so that it prevents the formation of sluggish water columns from the outset and therefore does not interfere with the function, shock-like aeration actions.

The above object is achieved in that the opening width of the ventilation opening can be regulated continuously or in several stages within a range in which air flows in such small quantities that it bubbles through water columns in the vacuum line.

The peculiarity of the invention, namely the constantly changing opening width of the air inlet openings, offers the advantage that the air supply is regulated as required at every moment. The vents close to the extent that they result from opening several Suction valves in various houses provide enough normal air intake to remove the waste water and to keep the waste water volume in the vacuum line at a low value. If the frequency of the opening of the suction valves and thus the simultaneity factor decreases, the clear width of the controllable ventilation openings increases, so that more air flows into the vacuum line, which adds to the air flowing in via the house connections.

Since an existing partial vacuum can only suck up water columns a few meters at a time, vacuum lines with higher gradients have to be divided into several short, rising, and in-between sections of the line. Also in the plane, vacuum lines are usually laid alternately with line sections rising and falling over a small height (see DE-PS 26 41 110). If one operates such vacuum drainage systems without the regulated ventilation devices proposed according to the invention, water columns extending from bottom to top are formed on many short slope sections of the vacuum lines, which can make up a total of more than 60% of the line cavity. If there are now controllable aeration devices according to the invention, the many short water columns in the vacuum line contain more or less dissolved air contained in the water in the form of bubbles. The water columns then often have the same length and height as before because they cannot be longer than this in a short, rising line section, but they consist to a greater or lesser extent of air than water, are accordingly lighter and can be opened when opening of suction valves via the house connection lines, air entering suddenly due to their lower inert mass can be accelerated better. The water volume replaced by air in the water columns is displaced into the collecting tank. The result can be in the vacuum Pipes of a drainage system according to the invention are up to about 50% less water than without the aforementioned controllable ventilation openings.

Another advantage of the new system compared to the prior art is that the pressure conditions in the vacuum lines are not subject to large fluctuations that are difficult to predict from the start and can lead to malfunctions. Larger vacuum pumps are also not required because of the additional air volume let in via the ventilation devices. In times of heavy wastewater, enough air is introduced through the house connection lines through frequent opening of the suction valves, so that the controllable ventilation openings can be completely or almost completely closed. The vacuum pumps therefore only need to be dimensioned in accordance with the waste water volume occurring at peak times and the associated air volume flowing in via the house connection lines. The air volume can even be smaller than in systems without a ventilation device according to the invention, and accordingly the vacuum pumps can also be dimensioned smaller in individual cases, because the system can also be used in quiet times when the smaller amounts of air set on the suction valves would not be sufficient for trouble-free operation. works perfectly when the ventilation openings are open.

Finally, the improved aeration of the waste water should be mentioned as an advantageous side effect.

In a preferred practical embodiment of the invention, at least one ventilation device is arranged at the outer end of a vacuum line. The air flowing in is then effective over the entire length of the line. In a further preferred embodiment, ventilation devices are attached to a vacuum line between a larger number from near a collecting tank closed connecting lines and a smaller number of connecting lines further away from the collecting tank. In this way, in addition to the basic advantage described, it is achieved that the wastewater is not sucked backwards as a result of the vacuum reservoir in the outer line regions. Further expedient places at which ventilation devices according to the invention can be arranged are located in the flow direction before problem sections of the vacuum line, for. B. in front of larger incline sections or z. B. culvert.

Reliability is required for vacuum drainage systems, which must be measured against that of conventional systems with free fall lines. The reliability of the moving parts, i.e. the pumps, valves and actuators, plays a decisive role in this. In order to ensure trouble-free operation of the proposed vacuum drainage systems, it is provided in a further preferred embodiment of the invention that the adjusting device for changing the opening width of the ventilation opening consists of a diaphragm piston which can be acted upon by the negative pressure of the vacuum line and which, when the absolute pressure drops, acts as a valve element against one Return spring pulls into a position reducing the ventilation opening. In this case, the line connection between the vacuum line and a cavity delimited by the membrane piston is expediently designed with a throttle point, so that in each case only a certain time elapses until a pressure change in the vacuum line communicates itself to the membrane piston. Short-term pressure changes, as they occur in particular when opening the suction valves on the house connection lines, therefore do not influence the regulation of the ventilation opening. In order to adapt to the different circumstances of different drainage systems and different vacuum lines of the same drainage system, the opening width of the throttle point is preferably one adjustable. Another individual setting option in a preferred practical embodiment of the invention is that the length of a control rod between the membrane piston and the valve member is adjustable. This allows the largest opening width of the ventilation opening to be set. Overall, a range of about 3 to 700 mm² will be selected as the adjustable clear cross section of a ventilation opening. It can also be provided that the ventilation opening closes completely under certain operating conditions.

A vacuum drainage system normally has ascending inspection pipes arranged at certain intervals on the vacuum lines, which are normally covered tightly by removable sealing caps. In the house connections there are house shut-off devices in the direction of flow behind the suction valve, the closing elements of which block the connection to the vacuum line in the meantime between the construction of a drainage system and the connection of a house. It is known to design the upper ends of the inspection pipes and the inspection openings on the house shut-off devices identically. This fact is used in a further embodiment of the invention, in which it is proposed that the ventilation opening, the valve member, the actuating device and the line connection to the actuating device form a structural unit with a closure cap that fits on an inspection pipe on a vacuum line.

The invention is explained below with reference to the drawing. There is the outermost, ie the most distant end of a vacuum station shown a vacuum line 10, the z. B. can have an inner diameter of 75 to 220 mm and is usually made of plastic. A riser pipe 12 is connected to the vacuum line 10, which rises and rises in the course of the earth, which z. B. can be a conventional inspection pipe or a riser pipe leading to a house shut-off device with, for example, an inner diameter of 40 mm. The riser pipe 12 shown broken off is sealed off at the upper end by a cap-shaped end piece 14. This end piece also fits other inspection pipes and riser pipes on house connections.

A cylinder 18 is welded or glued to the end piece 14 via an intermediate piece 16. These parts are also preferably made of plastic and, in the example, form an extension of the riser pipe 12. In the upper end wall 20 of the cylinder 18 there is a connection opening 22 to which a connecting line 24 to the riser pipe 12 is connected. The inner cavity of the cylinder 18, which is closed off at the lower end by a membrane 26, is thus constantly subjected to the negative pressure prevailing in the vacuum line via the connecting line 24 and the connection opening 22. While this strives to pull the membrane 26 upwards, a compression spring 28 clamped in the cylinder 18 presses the membrane 26 in the downward direction. With the membrane 26 a downwardly extending control rod 30 is connected, which carries a truncated cone-shaped valve member 32 which more or less closes a ventilation opening 34 in the end wall of the end piece 14 when the membrane 26 is moved. The ventilation opening 34 can, as shown, be cylindrical, but alternatively also conical to match the valve member 32. The control rod 30 is suitably adjustable in length by z. B. consists of at least two axially adjustable relative to each other or z. B. can be screwed into the valve body 32 at different depths.

If the intermediate piece 16 is tubular, one or more holes 36 must be present on it so that the interior of the vacuum line 10 with the ventilation opening 34 is open atmosphere.

The sensitivity or sluggishness of reaction of the adjusting device consisting of parts 18 and 26 to 30 for the ventilation opening 34, which can be regulated in its opening width, can be changed by means of an adjustable throttle point 38 at the connection opening 22. The setting is made e.g. B. by means of an adjusting screw 40, which is screwed more or less deep into the free cross section of the connecting line 24 at the terminal 22, depending on the desired inertia.

The ventilation device described above requires no maintenance after assembly within long intervals. The vacuum drainage systems of the type mentioned at the outset can basically be operated in the same vacuum range as before. Since the actuating device 18, 26 to 30 described in the example uses the negative pressure in the vacuum line 10 as the drive source, there are no complications in connection with a special energy supply. Nevertheless, there is in principle the possibility of using electrically or electronically controlled actuating devices as actuating devices for the proposed controllable ventilation openings, in which pressure or water level sensors generate signals which are converted into electrical control signals for the actuating device.

Up to this point, it has been assumed above that the ventilation openings 34 mentioned are used in vacuum drainage systems in which the suction valves are each opened and closed by a pneumatic control device, as described, for example, in DE-PS 24 62 295 and DE- OS 35 25 729 are shown and described. Here, at a certain maximum water level in a collection container in front of the suction valve, if possible via air upholstery in a riser pipe that extends upwards from the collecting container - a pneumatic switching valve is opened, which on the one hand triggers the opening of the suction valve directly or indirectly, and on the other hand starts a pneumatic time switch that closes the suction valve again after a certain period of time. The time period is set such that the air volume admitted into the vacuum line together with the wastewater when an exhaust valve is opened is 2 to 15 times the admitted wastewater portion. While according to DE-PS 24 55 551 this air volume is let into the vacuum line after the wastewater portion, DE-OS 35 25 729 provides that the greater part of the air volume let in each time a suction valve is opened before and / or during the Sucking in the wastewater portion is let into the vacuum line.

In the vacuum drainage system proposed here, too, the total volume of air admitted into the vacuum line over a longer period of time is preferably 2 to 15 times the total volume of wastewater admitted. However, since a large part of the air enters the vacuum line through the ventilation openings 34 described, the air volume let in when a suction valve is opened can be substantially smaller than before. This distribution of the air supply to the suction valves on the house connections and on the ventilation openings 34 not only has the advantage of better economy because the air supply via the ventilation openings 34 can be minimized because of their regulation, but also the further advantage that the previously when opening of the suction valve on a house connection strong noises caused by the intake of air can now be reduced.

The known pneumatic control devices with time switches have always had the function of the suction valve to be kept open so long that all waste water that had accumulated in the collection container in front of a suction valve could be sucked off and then a certain amount of air could flow into the vacuum line. It has now surprisingly been found that in the vacuum dewatering system according to the invention with controllable ventilation openings, the control devices with time switches can be dispensed with. All that is required is a switching valve actuated by the water pressure in the collecting container upstream of the suction valve or the air pressure in a riser pipe connected to the collecting container, as was used according to DE-PS 24 62 295 at the entrance of the known control devices for the suction valve, in order to maintain a certain maximum water level trigger the opening of the suction valve in the collection container and close the suction valve again immediately after the complete or partial extraction of the waste water from the collection container. If air is bubbled in at the same time as the waste water flows through the suction valve, as described in DE-OS 35 25 729, there is no hard blow after the passage of the waste water when the suction valve is closed, but instead the air-permeated waste water can flow from the house to the main vacuum line under the street with a slow flow rate when the connecting pipe is slightly inclined. The amount of air admitted through the suction valve before the waste water portion is preferably about 10 to 25% and the amount of air flowing in through the suction valve in the form of bubbles and beads is preferably about 30 to 50% of the water volume of the waste water portion. The rest of the total air required to operate the drainage system is also regulated in this case, where the suction valves are not kept open by a timer for a certain period of time, but only until all or part of the waste water collected in front of the valves is sucked off Vents entered. Overall, this is over a longer period of time the air volume again 2 to 15 times the wastewater volume. Under the same conditions, however, the air consumption is lower, and the system nevertheless operates more trouble-free than a conventional comparable system without the simple automatic control mechanism by means of the ventilation openings 34 described.

It has been shown in practical tests that a drainage system according to the invention with controllable ventilation openings 34 works particularly well when the vacuum line, which in the usual way consists of plastic pipes with essentially the same diameter as in known drainage systems of this type, is laid at intervals of approximately each time it is laid in the pipe trench 20 to 30 m is relined in such a way that a high point arises in the line which is approximately 15 to 20 cm higher than the low points of the line which are approximately 10 to 15 m away therefrom. The latter form the sinks, in which not as much wastewater in the form of a plug can accumulate in the system according to the invention as in conventional vacuum drainage systems, because the air flowing in continuously through the ventilation openings displaces a corresponding volume of wastewater from the line. The adjacent ascending and descending line sections formed in this preferred type of laying the vacuum line are essentially of the same length if the line is laid over a certain distance as a whole or on average approximately horizontally, slightly upward or downward.

The automatic control of the air supply of the drainage system according to the invention can be further improved and supplemented by the switching valve, which triggers the opening of the suction valve, depending on the instantaneous strength of the vacuum in, by means of a corresponding actuating device, as described above in connection with the ventilation openings 34 Closing direction is preloaded, as described in European patent application 87104153.9, so that it is weaker Vacuum is more likely, ie opened at a lower water level in the collection container in front of a suction valve than with a strong vacuum in the vacuum line. This means that if the vacuum line begins to become “clogged” by too much waste water, not only through more open ventilation openings 34, but also through more frequent opening of the suction valves, more air is admitted into the vacuum line and the simultaneity factor is also improved. The pressure surges that occur when the suction valves essentially open at the same time as a result of a suddenly greatly increased air flow now have a much easier time accelerating the water plugs constantly bubbled with air in the sinks of the line and driving them over the next high point or over several high points the mass of water plugs interspersed with air is significantly smaller than that of plugs of the same size consisting only of waste water. In addition, the water plugs constantly interspersed with air in the drainage system according to the invention have a substantially lower pipe friction when moving along the line, which also contributes to their better acceleration and higher transport speed.

Another advantage of the new drainage system is that there is always a gas and liquid flow to the vacuum station in the vacuum line. This gives a wastewater portion flowing in from a house connection in the transverse direction immediately the correct deflection to the vacuum station, whereby the previously often observed backward flow is effectively avoided.

The great practical importance of the invention is evident from the fact that in vacuum drainage systems for residential developments in the 24-hour cycle, waste water accumulates only for about four to five hours in such a way that the suction valves open frequently enough to have a result of the simultaneity factor that then occurs to be able to count on the proper functioning of the system. In contrast, with conventional vacuum drainage systems, approx. 80% of the total operating time is problematic because the suction valves are only operated rarely. If you want to introduce enough air into the piping system even in these times without additional ventilation openings, the suction valves must remain open for a long time with each opening process so that a lot of air can flow in each time. However, this again has the disadvantage that one works with a large, uneconomical excess of air in times when the suction valves are operated at a higher frequency. The proposed vacuum drainage system, on the other hand, ensures more economical air consumption during active times of the day through greater throttling at the controllable ventilation openings and through better ventilation openings 34 for better functioning during problematic rest periods.

With regard to the exemplary embodiment described, it should be noted that the invention is not limited to the embodiment shown in the drawing. For example, the parts shown can also be arranged vice versa such that a e.g. conical valve body 32 points with the tip downwards and is pushed further in the closing direction into the opening 34 by a membrane 26 which is subjected to the system vacuum on its underside with an increasingly strong vacuum. In this latter case, the line 24 and the opening 36 are to be arranged such that the membrane 26 is exposed to the outside atmosphere on its upper side and to the vacuum on its lower side.

Claims (10)

1.Vacuum drainage system with one or more collecting tanks under vacuum and connected to it, alternating rising and falling vacuum lines, to which the normal pressure connecting lines of the units to be dewatered are each connected via a suction valve, which opens automatically when one a certain amount of water from 5 to 40 liters has accumulated in front of it, and with each opening process, together with the waste water, lets air into the vacuum line, at least one ventilation opening controlled by a control device depending on the water level or pressure at a specific point on the vacuum line being arranged on the vacuum line , characterized in that the opening width of the ventilation opening (34) can be regulated continuously or in several stages within a range in which air flows in such small quantities that it bubbles through water columns in the vacuum line (10). 2. Drainage system according to claim 1, characterized in that at least one ventilation opening (34) at the outer end of a vacuum line (10), in front of a slope section or culvert or between a larger number of connecting lines connected near a collecting tank and a smaller number of further from the collecting tank remote connecting lines is arranged. 3. Drainage system according to one of claims 1 to 2, characterized in that the adjusting device (18, 26-30) for changing the opening width of the ventilation opening (34) has a vacuum piston (10) which can be acted upon by a diaphragm piston (26), which when the absolute pressure drops Pulls valve member (32) against a return spring (28) into a position that reduces the ventilation opening (34). 4. Drainage system according to claim 3, characterized in that the line connection (24) between the vacuum line (10, 12, 14) and one of the membrane piston (26) delimited cavity (18) is formed with a throttle point (38). 5. Drainage system according to claim 4, characterized in that the opening width of the throttle point (38) and / or the length of a control rod (30) between the diaphragm piston (26) and the valve member (26) is adjustable. 6. Drainage system according to one of the preceding claims, characterized in that the ventilation opening (34), the valve member (32), the actuating device (18, 26-30) and the line connection (24) to a unit with an inspection pipe (12) a suitable sealing cap (14) form a vacuum line (10). 7. The method for operating a vacuum drainage system according to claim 1 with one or more vacuum tanks under vacuum and connected to them, alternatingly rising and laid vacuum lines, to which the normal pressure connecting lines of the units to be dewatered are connected via a suction valve, which is automatically opened when a certain amount of water from 5 to 40 l has accumulated in front of it, and in addition to an amount of air flowing into the vacuum line together with the waste water during each opening process, additional air is admitted into the vacuum line via a ventilation opening, thereby characterized in that a small amount of air regulated in dependence on the water level or pressure in the vacuum line is continuously admitted via the ventilation opening and bubbles through water columns standing in the vacuum line. 8. The method according to claim 7, characterized in that when opening a suction valve only before and / or during the admission of wastewater into the vacuum line, air is admitted into the vacuum valve. 9. The method according to claim 7 or 8, characterized in that when opening a suction valve about at most about the same volume of air as waste water is admitted into the vacuum line, and the volume of air let in through the ventilation openings is greater than that of the suction valves let-in volume of waste water. 10. The method according to any one of claims 7 to 9, characterized in that the suction valves are opened at a stronger vacuum in the vacuum line only after a larger amount of water has accumulated in front of them than with a weaker vacuum.

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