EP1559841B1 - Method of installation and/or working of a sewage collection well - Google Patents

Abstract

A sub-surface waste water collector and treatment shaft (2) is closed by a cover and has an atmosphere (8) that is potentially explosive. The shaft has a part-submerged water pump (12) that is operated depending upon the water depth (0). The pump is operated by a pump control unit (30) in conjunction with a time switch and pressure sensor.

Description

The invention relates to a sewer manhole with explosive or non-hazardous atmosphere above the sewage level, wherein in the wastewater at least one sewage pump is immersed, the sewage pump can be switched on depending on an upper level of the sewage and after a delivery time off again.

Such a sewage collection shaft is known from the prior art. For such sewage collection shafts or their operation guidelines must be complied with, according to which it must be avoided that mechanically moving parts come into contact with the air-gas mixture of a potentially explosive atmosphere. So it must be avoided in the discharge of wastewater, that moving parts of the sewage pump come into contact with the explosive atmosphere by excessive drop of the sewage level. This means that the sewage pump may not be switched off too late.

DE 39 18 294 A1 describes a device for monitoring sewage pumping stations. The wastewater pump is connected to a monitoring device that continuously monitors the pump output and compares this output with previously determined reference values.

Out DE 31 10 735 A1 a dry run protection device for sewage pumps is known. The device has two modes which are used depending on the amount of wastewater. At low inlet, the pumps are only switched on and their running time compared with a fixed time. If the pump runs too long, the system will run dry and an alarm will sound. With a strong inflow is pumped as long as a correspondingly provided membrane switch signals the concern of a Drukkes. If there is no pressure left, the system is switched off.

In sewage collection shafts, where the atmosphere above a sewage level is not at risk of explosion, it should also be avoided that the sewage pump is exposed. Such exposure leads to air being sucked in, whereby the reliable operation of the sewage pump is no longer guaranteed. It is therefore desirable even in sewer manholes with non-hazardous atmosphere to limit the delivery time such that the Abwsserförderpumpe permanently immersed in the wastewater.

There is also the problem that the devices that detect a maximum waste water level in the sewer manhole and are located above the sewage pump should not be continuously submerged in the sewage for accurate detection even over a long period of operation.

In order to achieve that on the one hand after reaching a maximum waste water level, the detection devices completely be released, but on the other hand is excluded that the sewage pump is also exposed, it is necessary in the installation of conventional sewer manholes to determine the optimal delivery time of the sewage pump by an installer using a stopwatch. The optimal delivery time depends, among other things, on the back pressure against which the sewage pump removes the wastewater. If a low back pressure is present, the delivery time is shorter, with higher back pressures the delivery time increases. An inflow of wastewater when the pump is activated also influences the optimum delivery time.

The procedure described is disadvantageous for several reasons. First, the delivery time must be determined manually and the pump must be programmed accordingly. In addition, it may happen that during the installation of the sewer manhole counterpressure from "zero" to "maximum" is not applicable, so that the determination of the delivery time is fraught with some uncertainty.

Proceeding from this, the present invention has the object, a method for installation and / or 3a to operate a sewer manhole of the type assumed to be known, with the reliable and with little effort an optimal delivery time can be determined.

This object is achieved in that a pump control, a timing device and a pressure sensing device is provided, wherein with the timing device a time period between the detection of two different heights of the waste water level corresponding, predetermined pressure values can be measured, wherein depending on the measured time duration, the delivery time of the pump control can be predetermined.

The wastewater collection shaft according to the invention allows the determination of an optimal delivery time without manual intervention. In principle, the time required to lower the wastewater level by a certain amount is determined and the delivery time is determined on the basis of this time period. The beginning and the end of the mentioned time period correspond to the detection of predetermined pressure values which correspond to different heights of the wastewater level.

The delivery time can be specified during installation and / or maintenance of the wastewater collection shaft. This funding period Can be maintained for further operation of the sewer manhole without changes. The delivery time can correspond to a multiple of the measured time duration.

It is particularly advantageous if the delivery time can be varied as a function of a respectively last measured time duration. This makes it possible, without manual intervention, to be able to adapt the delivery time in accordance with a changing counterpressure applied to the sewage pump. In this case, successive measurements can also be taken into account pro rata.

The pressure sensing device may include a dynamic pressure bell and / or a back pressure hose. This has the advantage that no electrical components come into contact with the potentially explosive atmosphere.

Furthermore, the pressure-sensing device may have a dynamic pressure sensor, a differential pressure sensor and / or a pressure switch, in particular a pressure switch with hysteresis. These sensors or switches may be connected downstream of the dynamic pressure gate and / or the back pressure hose, wherein the switches or sensors should be arranged in a non-hazardous environment. The pressure detection device or the switches or sensors can communicate with the pump controller electrically or via radio. The use of a radio link has the advantage that the pump control also at one distant location of the sewer manhole is positionable.

The invention further relates to a method for operating a sewer manhole.

Figur 1 -

eine schematische Seitenansicht eines Abwassersammelschachts,

Figur 2 -

einen Ausschnitt der Seitenansicht gemäß Figur 1, wobei die Druckerfassungsvorrichtung einen Druckschalter aufweist,

Figur 3 -

eine der Figur 2 entsprechende Ansicht, wobei die Druckerfassungsvorrichtung einen Differenzdrucksensor aufweist.

Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings. Show it:

FIG. 1 -

a schematic side view of a sewer manhole,

FIG. 2 -

FIG. 2 shows a detail of the side view according to FIG. 1, wherein the pressure-sensing device has a pressure switch,

FIG. 3 -

a view corresponding to Figure 2, wherein the pressure sensing device comprises a differential pressure sensor.

According to FIG. 1, a wastewater collecting shaft 2 is provided, which is arranged below a cover 2a. Within the sewage collection shaft 2 waste water 4 can be collected, which forms a waste water level 6. The space 8 above the water level 6 is at risk of explosion.

The waste water 4 is fed to the sewage collecting shaft 2 through a supply line 10. In the collected wastewater 4 at least partially submerged sewage pump 12 a. This has a spiral housing 14, which should always be immersed in the wastewater 4. The pump 12 is over a Flange 16 mounted in an anchoring area 18 in the ground 20.

The pump 12 is followed by a drain line 22, wherein the pressure applied in the drain line back pressure can vary.

Above the sewage level 6 within the sewage collecting shaft 2, a dynamic pressure bell 24 is arranged, which communicates via a dynamic pressure hose 26 with a switching / sensor device 28 in connection. The device 28 communicates with a pump controller 30.

FIG. 2 shows a unit 28a with a hysteresis-type pressure switch corresponding to the unit 28 according to FIG.

The unit 28a has a housing 28b which delimits an inner space 28c in which two gas-tight membranes 28d and 28e arranged adjacent to one another are provided. The membranes 28d and 28e define a membrane space 28f. Through the membrane 28 e, a downstream switch 28 g is actuated, which is isolated via a potting compound 28 h from the housing of the adjacent pump control 30 a.

The interior 28c of the unit 28a is connected via a housing stub 28i with the illustrated back pressure hose 26a in connection, which is connected at its lower end to the dynamic pressure bell 24a.

In the event of damage to the diaphragm 28d, an explosive mixture, which is supplied via the ram pressure hose 26a to the inner space 28c, can be discharged through a laterally arranged channel 28j.

Only indicated in FIG. 2 is a second unit 28k, which corresponds in its construction to the unit 28a. With such a second unit, the sewage level 6 can be detected via another, not shown, back pressure bell. Such a second device 28k may be provided for safety reasons to provide a redundant arrangement.

With reference to FIG. 3, the unit 28 according to FIG. 1 is designed as a differential pressure sensor 281. This has a housing 28m, which is filled with a potting compound 28n. The housing 28m has a first housing socket 28o, which communicates via a dynamic pressure hose 26b with a dynamic pressure bell 24b. The housing 28m has a second housing spigot 28p against which a simple ambient pressure is applied. Inside the potting compound 28n, a differential pressure sensor element 28q is provided, which is suitable for detecting a differential pressure between the pressure applied to the housing connection 28p and to the housing connection 28o. The differential pressure sensor element 28q is connected via a downstream board 28r and via electrical lines 28s to a pump control 30b.

Below, the installation and operation of the sewage collection shaft 2 will be described. For this purpose are in Figure 1 indicates different levels or heights of the sewage level 6 with "0" to "IV".

When the waste water 4 reaches an upper level designated "0", a corresponding pressure is applied in the dynamic pressure hose 26, which pressure can be detected by the unit 28. Upon reaching this uppermost level "0", the pump 12 is turned on, so that the sewage level 6 drops. The water level heights "I" and "II" correspond to given pressure values. The period of time elapsing between the detection of these pressure values corresponding to water level heights "I" and "II" can be measured by means of a time measuring device (not shown). This period of time is, for example, 5 seconds. It is dependent on the counterpressure present in the discharge line 22, against which the pump 12 must discharge the wastewater 4. On the basis of the measured time duration, the entire delivery time can now be determined, for example with the aid of a predetermined multiplier. If the pump 12 is to be turned off when reaching a water level "III", the measured time duration would have to be multiplied by a factor of "2". If a waste water level 6 denoted by "IV" is to be reached, the measured time duration would have to be multiplied by a multiplier of "3".

Of course, the switching on of the pump 12 can also be initiated when the height "I" of the wastewater mirror 6 is reached. In this case, the uppermost level from which the waste water pump 12 is turned on corresponds to highest height of the heights corresponding to the predetermined pressure values. In this case, the turning on of the sewage pump 12 and the start of the measurement of the period between the detection of the heights "I" and "II" of the sewage mirror 6 coincide.

With the described method, the wastewater collection well 2 can be put into operation without the need for manual intervention by an installer. However, it is particularly advantageous if the delivery time is variable. This will be explained below with reference to an example.

If, for a first measurement between the heights "I" and "II" of the wastewater mirror 6, the measured time duration is, for example, 5 seconds, this measured time duration can be multiplied by a predetermined multiplier, for example "3", for a total delivery time of 15 seconds. to obtain. After expiration of this delivery time, the pump 12 is turned off. When the sewage level 6 subsequently rises again to the level "I", the pump 12 is turned on and the time to reach the height "II" can be measured again. Should the time duration of this second measurement be equal to the time duration of the first measurement, no change in the delivery time is required. If the time duration of the second measurement is shorter than that of the first measurement, this second measurement of the delivery time can be used as a basis. For example, in the second measurement, the time duration is 4 seconds, so that a multiplier of "3" determines a delivery time of 12 seconds in total can be. This ensures that the dynamic pressure bell 24 can be completely exposed by wastewater 4.

If, however, due to a higher backpressure in the drain line 22, the measured time duration of the second measurement is longer than that of the first measurement, the time duration of the second measurement can not be readily based on the delivery time, without the risk that too long is pumped, which could lead to an exposure of the volute casing 14 of the sewage pump 12. In order to minimize this risk, the second, longer period of time is initially taken into account only proportionally. With a freely selectable proportion factor of, for example, 50% with a measured first time duration of 5 seconds and a measured second time duration of 10 seconds, a new delivery time would initially be based on a duration of only 7.5 seconds. These 7.5 seconds are used to determine the funding period with the o.g. Multiplier multiplied.

If a shorter time duration is then measured in a subsequent, third measurement, this can, as described above, again be based directly on the new delivery time. If the time duration of the third measurement is equal to the time duration of the second measurement, this can be maintained. If the time duration of the third measurement is longer than that of the second measurement, for example 12.5 sec., The time duration of the second and the third measurement can again be taken into account proportionately, which with a proportional factor of 50% to a delivery time of 10 sec. This funding period would again be multiplied by the predetermined multiplier.

Claims (8)

1. Method for installing and/or operating a sewerage collection well (2) with an explosion-risk or non-explosion-risk atmosphere (8) above the sewerage level (6), whereby a sewerage pump (12) is immersed into the sewerage (4) and is switched on when the highest point (0) of the sewerage level (6) is reached and is switched off again after a pumping period, and whereby two pressure values are predefined and measured which correspond to different points (I; II) of a sewerage level (6),
   characterised by the following steps:

   - the duration between the measurement of the pressure values assigned to the points (I; II) of the sewerage level (6) is measured,

   - the pumping time is predefined in dependence upon the measured duration.
2. Method according to claim 1,
   characterised in that
   the pumping time is adapted on the basis of successive duration measurements according to the following stipulations:

   - if the duration of a second measurement is equal to the duration of a first measurement the pumping time is not changed,

   - if the duration of a second measurement is shorter than the duration of a first measurement, the pumping time is adapted in dependence upon the duration of the second measurement,

   - if the duration of a second measurement is longer than the duration of a first measurement the pumping time is adapted in dependence upon the durations of the first and the second measurement.
3. Method according to claim 1,
   characterised in that
   the durations of the first and the second measurement are taken into consideration in accordance with a predefinable, particularly variable, ratio.
4. Method according to one of the claims 1 to 3,
   characterised in that
   the pumping time is predefined during installation and/or maintenance of the sewerage collection well (2).
5. Method according to one of the claims 1 to 4,
   characterised in that
   the pumping time is equal to a multiple of the measured duration.
6. Method according to one of the preceding claims,
   characterised in that
   the pumping time is changed in dependence upon the last measured duration in each case.
7. Method according to claim 6,
   characterised in that
   the last measured duration in each case is taken into consideration only in part for the change in the pumping time.
8. Method according to one of the preceding claims,
   characterised in that
   the pressure detection system (24; 26; 28) communicates electrically and/or by means of radio with the pump control (30) .

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