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Title:
THE METHOD OF FLUSHING AND AERATION OF A PRESSURE PIPELINE AND THE WASTEWATER PUMPING DEVICE
Document Type and Number:
WIPO Patent Application WO/2017/196196
Kind Code:
A1
Abstract:
The method of the present invention is characterized in that: at the first stage, compressed air is supplied in the place of the pressure pipeline that is at a distance from the pumping device (3) of wastewater for the purpose of at least partial removal of wastewater from the remaining part of the pressure pipeline (2) and a reduction of the operating pressure of the pumping device (3) while it is started again, and at the second stage, compressed air is supplied during another pumping cycle in order to increase and maintain pressure that is close to the proper operating pressure of the pumping device (3), whereas after the proper wastewater operating pressure of the pumping device has been exceeded, the first stage "a") occurs. The device according to the invention is characterized in that the flushing device (7) of the pressure pipeline (2) possesses a horizontal pipe storage tank (6) of compressed air, whose beginning is found in the immediate vicinity of the pumping device (3), and its end is in the immediate vicinity of the place where compressed air is supplied to the pressure pipeline (2).

Inventors:
SZUSTER, Mirosław (Szuster Consulting, Naramice 30, 98-350 Biała, 98-350, PL)
Application Number:
PL2017/050025
Publication Date:
November 16, 2017
Filing Date:
May 12, 2017
Export Citation:
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Assignee:
SZUSTER, Mirosław (Szuster Consulting, Naramice 30, 98-350 Biała, 98-350, PL)
International Classes:
B08B9/032; B08B5/02; E03F1/00; E03F5/22
Foreign References:
PL195015B12007-07-31
CN205183227U2016-04-27
PL215041B12013-10-31
Attorney, Agent or Firm:
WITEK, Rafał (WTS Patent Attorneys, Witek Sniezko & Partner, ul. Rudolfa Weigla 12 53-114 Wrocław, 53-114, PL)
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Claims:
Claims

1. The method of flushing and aeration of the pressure pipeline of the pumping device of wastewater, and municipal wastewater in particular, where compressed air with a pressure that is higher than the proper operating pressure of the wastewater pumping device, for a pressure pipeline that is completely filled with wastewater, is supplied in order to empty it, is characterized in that:

a) at the first stage, compressed air is supplied in the place of the pressure pipeline (2) that is at a distance from the pumping device (3) of wastewater for the purpose of at least partial removal of wastewater from the remaining part of the pressure pipeline (2) and a reduction of the operating pressure of the pumping device (3) while it is started again;

b) at the second stage, compressed air is supplied during another pumping cycle in order to increase and maintain pressure that is close to the proper operating pressure of the pumping device (3), whereas once the proper operating pressure has been exceeded, the pumping device is switched off and the first stage "a") occurs.

2. The method according to Claim 1, characterized in that during the first stage "a)" the operating pressure of the pumping device (3) is lowered to the assumed minimum level while it is started again at the stage "b)'\

3. The method according to Claim 1, characterized in that during the second stage '¾)", once the proper operating pressure of the pumping device (3) has been exceeded and the maximum assumed operating pressure of the pumping device (3) has been reached, the first stage "a)" occurs.

4. The method according, to Claim 1, characterized in that during the first stage "a)", compressed air is supplied with such a pressure so as to ensure the rates of the self-deaeration of the pressure pipeline (2) from Im/s to 2m/s and greater.

5. The method according to Claim 1, characterized in that during the first stage "a)", compressed air is supplied to the pressure pipeline (2) at the moment the centrifugal pump (1) is being switched off, in order to use the kinematic energy of the accelerated liquid stream.

6. The method according to Claim 5, characterized in that initially compressed air is supplied under a lower pressure owing to the flow being throttled or reduced, in order to avoid a strong water hammer.

7. The wastewater pumping device with a collective sewage chamber that possesses at least one pump that is connected to the pressure pipeline and that possesses at least one flushing device for the flushing of the pressure pipeline, which possesses a compressed air source, connected through an air line to the pressure pipeline, and that possesses a control device for turning the flushing device on and off and controlling its parameters, characterized in that the flushing device (7) of the pressure pipeline (2) possesses a horizontal storage tank (6) of compressed air, whose beginning is in the immediate vicinity of the pumping device (3), and its end is in the immediate vicinity of the place where compressed air is supplied to the pressure pipeline (2).

8. The device according to Claim 7, characterized in that an automatic throttle valve (12) is installed on the air line (11), which reduces the flow and the pressure of compressed air.

9. The device according to Claim 7, characterized in that at least one controlled shut-off valve (13) is installed on the air line (11) to supply compressed air to the pressure pipeline (2).

10. The device according to Claim 7, characterized in that the beginning of the horizontal pipe storage tank (6) is connected by an additional air line (14) with an additional throttle valve (15) and an additional controlled shut-off valve (16) that are installed on it.

1 1. The device according to Claim 7, characterized in that in the starting section of the pressure pipeline (2), near the pumping device (3), a pressure transducer is installed (17).

12. The device according to Claim 7 or 8 or 9 or 10 or 1 1, characterized in that in the control device (8) is adapted to the method according to one of Claims 1 - 6.

13. The device according to Claim 7, characterized in that the horizontal pipe storage tank (6) is made up of a pressure sewage pipe that is placed in soil along the pressure pipeline (2).

Description:
The method of flushing and aeration of a pressure pipeline and the wastewater pumping device

The object of the present invention is the method of flushing and aeration of a pressure pipeline according to the preamble of Claim 1 and the adequate wastewater pumping device according to the preamble of Claim 7.

These methods and respective devices are well-known from the following patent documents, for example: EP 1894638 Bl and DE 2850202 C2.

Pressure pipelines, through which wastewater for wastewater transporting equipment is supplied in batches by at least one pump from a collective sewage chamber, need to be flushed in regular time intervals and depending on the size of the wastewater inflow to the collective chamber, and depending in particular on their retention time in the pressure pipeline. The practice shows that when raw municipal sewage that contains biological impurities is held in the pressure pipeline for a period that is longer than two hours, there occur biological processes in it that lead to its putrification when there is no access to oxygen, which in turn results in the production of unpleasant odours as a result of its decomposition, especially in the places where it is discharged to decompression chambers in pressure sewer systems. In order to reduce these processes of biological sewage decomposition in conditions with no oxygen, sewage pressure pipelines are flushed with compressed air, usually in regular time intervals, and also depending on the sewage inflow size so that, if possible, there are no residues of organic substances that cause among others the production of hydrogen sulfide, which is hazardous to health and life.

The aforementioned regular flushing of the whole wastewater pressure pipeline with the aid of compressed air with a pressure that is higher than the operating pressure of the wastewater pumping device, for a pipeline that is completely filled with wastewater, is sometimes uneconomical for various reasons as flushing processes occur also when no flushing is required at all. In a slightly improved method of flushing of the whole wastewater pressure pipeline, according to the method described in the following Patent Document: EP 189463 8 Bl , flushing of the entire pressure pipeline depends on the size of the current sewage inflow to the collective chamber of the sewage pumping device, and it is not realized in a given period of time if, at a given moment, this is not required.

This improved method offers some energy savings, yet it does not solve the elementary problem of a sewage pumping device that possesses centrifugal pumps as the capacity of a given centrifugal pump depends from instantaneous flow resistance in the pressure pipeline.

In practice, external factors have an impact on the capacity of the centrifugal pump. This includes forcing compressed air into the sewage pressure pipeline, which results in variable flow resistances, the result being that the centrifugal pump works in a capacity range that is not permitted by the manufacturer, and there may occur large vibrations while cavitation occurs on the pump rotor, which leads to an early wear of the pump or even its failure.

When sewage is being pumped into a pipeline from which sewage has been completely removed by compressed air, the centrifugal pump initially possesses capacity that is too large and it is threatened by increased vibrations and cavitation. If the pump is pumping sewage to a pressure pipeline that has been emptied in part only, as a result of airlocks it may have too low capacity, which also involves the risk of cavitations and increased vibrations; furthermore, no sufficient flow rate is ensured for the self-purification of the pipeline.

In the case of air pumping devices, like those from Patent Description no. PL 211675, the aforementioned problems are not so serious, yet with total periodical emptying with compressed air, e.g. once or twice a day, and with high working pressures of 5 to 10 bar, there occur fairly strong water hammers when sewage is forced into an empty pressure pipeline, which may have an impact on the stability of the air sewage pumping device.

Flushing of the sewage pressure pipeline with compressed air is expected to ensure at least two- or three-fold exchange of its entire volume. However, as sewage putrification begins if there is no access of oxygen from outside as soon as after two hours of remaining in the pressure pipeline, an intervention consisting in introducing oxygen into the sewage pressure pipeline needs to be started as early as after 2 to 4 hours of their remaining in the pressure pipeline. Possibly, one also needs to consider the degree of their dilution and the condition of possible putrification on the inlet to the collective chamber of the sewage pumping device.

Furthermore, air relief valves valves that are used on the pressure pipeline cause a partial escape of compressed air that is used for flushing the pressure pipeline, which constitutes a problem of an economical, teclmical and technological nature.

The purpose of the present invention is to improve the method and the device for wastewater transport that are known from the state of the art, so that flushing of the sewage pressure pipeline with compressed air should not cause the aforementioned problems and be economically justifiable.

The method according to the invention consists in the following:

- at the first stage, compressed air is supplied in the place of the pressure pipeline that is at a distance from the pumping device of wastewater for the purpose of at least partial removal of wastewater from the remaining part of the pressure pipeline and a reduction of the operating pressure of the pumping device while it is started again;

- at the second stage, compressed air is supplied during another pumping cycle in order to increase and maintain pressure that is close to the proper operating pressure of the pumping device, whereas after the proper operating pressure has been exceeded, the pumping device is switched off and the first stage occurs.

As an advantage, during the first stage, the operating pressure of the pumping device is lowered to the assumed minimum level while it is started again at the stage.

As an advantage, at the second stage, after the proper operating pressure of the pumping device has been exceeded and the maximum assumed operating pressure of the pumping device has been reached, the first stage occurs.

As an advantage, during the first stage, compressed air is supplied with such a pressure so as to ensure the rates of the self-deaeration of the pressure pipeline from lm/s to 2m/s and greater. To the best advantage, during the first stage, compressed air is supplied to the pressure pipeline at the moment the centrifugal pump is being switched off, in order to use the kinematic energy of the accelerated liquid stream.

Equally as an advantage, initially the compressed air is supplied under a lower pressure owing to the flow being throttled or reduced, in order to avoid a strong water hammer.

As an advantage, the place where compressed air is supplied to the pressure pipeline is located behind the pumping device at a distance adapted to the time during which sewage remains in a given pipeline in order to prevent sewage putrification. It is of particular advantage to supply the compressed air to the pressure pipeline in the place where remains the sewage which had passed through the pumping device two to four hours before.

In the device according to the invention, the flushing device of the pressure pipeline possesses a horizontal storage tank of compressed air, whose beginning is in the immediate vicinity of the pumping device, and its end is in the immediate vicinity of the place where compressed air is supplied to the pressure pipeline.

As an advantage, an automatic throttle valve is installed on the air line, which reduces the flow and the pressure of compressed air.

As an advantage, at least one controlled shut-off valve is installed on the air line to supply compressed air to the pressure pipeline.

As an advantage, the beginning of the horizontal pipe storage tank is connected by an additional air line with an additional throttle valve and an additional controlled shut-off valve that are installed on it.

As an advantage, in the starting section of the pressure pipeline, near the pumping device, a pressure transducer is installed.

To the best advantage, the control device is adapted to the method according to one of Claims 1 - 6.

As an advantage, the horizontal pipe storage tank is made up of a pressure sewage pipe that is placed in soil along the pressure pipeline. The advantage of the method according to the invention is that independently of regular flushing of the pressure pipeline 2 of sewage, it is possible to maintain pressure on at least the minimum level for the correct functioning of the centrifugal pump 1.

The advantage of the device according to the invention is the possibility to lower the costs of workmanship and foundation of the horizontal pipe storage tank owing to the use of the sewer pressure pipe.

The subject of the invention is presented in embodiment in the figure, where Fig. 1 presents a diagram including an example of the characteristics of the centrifugal pump with its permissible working parameters, Figs. 2 and 3 provide a graphical presentation of the application according to the invention in a conventional manner, and they illustrate the content from Claims 1 to 3; with one difference, i.e. the device in Fig. 3 additionally possesses a compressed air storage tank, and Fig. 4 provides a graphical presentation of the application according to the invention and it illustrates the content from Claims 4 to 5, while Fig. 5 provides a graphical presentation of the solution of the device according to the invention.

Fig. 1 presents an example of the characteristics of the centrifugal pump 1 with fields marked on it of working pressures that are correct for it and permissible working pressures, and with Ρ !ΙΜΧ marked as the assumed maximum working pressure and P m i n as the assumed minimum working pressure. Additionally, the curve is marked that illustrates the level of the vibrations of the centrifugal pump 1 for the entire range of its characteristics. When supplying compressed flushing air to the pressure pipeline 2, in a place that is far away from the pumping device 3 after removing sewage from the remaining section of the pressure pipeline 2, the pumping device 3 still possesses certain back pressure in the pressure pipeline after it has been started, and there is no case of pumping into an empty pipeline. This back pressure is usually too low and for this reason, during subsequent cycles of forcing sewage to the pressure pipeline 2, compressed air is supplied to it, which causes an increase of flow resistances, and thereby an increase of the working pressure of the pumping device so that work could always be ensured at least in the area of the assumed working pressures of the centrifugal pump 1. Furthermore, during each pumping cycle, sewage is aerated, which prevents its strong decomposition.

Fig. 2 and 3 provide a graphical presentation of the application according to the invention in a conventional manner according to the known solution of flushing devices, only that the device in Fig. 3 possesses additionally the storage tank 4 of compressed air.

Fig. 4 provides a graphical presentation of the application of the method according to the invention and it illustrates the content contained in Claims 4 to 5, only, as an advantage, compressed air is supplied to the pressure pipeline 2 at the moment the centrifugal pump is switched off, which causes the average flow rate of the water-gas mixture to be much higher, with the same flushing time of 30 minutes. This is an action that is beneficial for energy conservation considerations. Total emptying of the pressure pipeline 2 of sewage is advantageous to the self-deaeration of this pipeline while it is being filled with new portions of sewage, and it eliminates the use of air relief valves that are expensive and troublesome in operation. In order to prevent uncontrolled water hammers, the flow of compressed air is throttled at the beginning, or its pressure is reduced.

The device according to the invention is presented in Fig. 5 and it possesses a collective sewage chamber 5, where two centrifugal pumps 1 are placed that are connected with the pressure pipeline 2 via check and shut-off fittings, which are not marked in Fig. 5, as well as the flushing device 7 for flushing the pressure pipeline 2 and the control device 8 to control the parameters of the flushing device. The novelty of the device according to the invention is the use of the horizontal pipeline storage tank 6, which may be constituted by a pressure sewage pipe that is placed in soil along the pressure pipeline 2. The pressure pipeline ends with the expansion well 9.

The flushing device 7 possesses a source of compressed air 10, which is connected via the air line 11 to the pressure pipeline 2 and to the control device 8 for the purpose of switching the flushing device 7 on and off and to control its parameters. The automatic throttle valve 12 is installed on the air valve 1, which reduces the flow and pressure of compressed air. At least one controlled shut-off valve 13 to supply compressed air to the pressure pipeline 2 is installed on the air line 1 1. The beginning of the horizontal storage tank 6 is connected with the additional air line 14 with the additional throttle valve 15 that is installed on it and the additional controlled shut-off valve 16.

On the initial section of the pressure pipeline 2, near the pumping device 3, the pressure transducer 17 is installed. The control device 8 is adequately adapted to the flushing and aeration of the pressure pipeline 2 of the pumping device. Owing to the additional air valve 14 that is connected to the beginning of the horizontal storage tank 6, periodical flushing and aeration of the initial section of the pressure pipeline 2 is possible when the inflow of sewage to the collective sewage chamber 5 is small.

List of designations

1. Centrifugal pump

2. Pressure pipeline

3. Pumping devices

4. Accumulator tank

5. Collective sewage chamber

6. Horizontal pipe storage tank

7. Flushing device

8. Control device

9. Expansion well

10. Compressed air source

11. Air line

12. Throttle valve

13. Controlled shut-off valve

14. Additional air line

15. Additional throttle valve

16. Additional shut-off valve

17. Pressure transducer




 
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