Device for sewage pumping stations

Abstract

 The invention concerns a device for pump stations comprising two or more pump units (4), (5). The pressure pipes (8), (9) from the pump units are connected via a shunt lead (10) which is kept open during short intervals at pump starts, thus obtaining a backward flow through the pump(s) which not operate at the moment, thereby flashing out pollutions through the inlet(s) of said pump(s).

Description

[0001] A Device to diminish the risk for clogging of pumps for sewage water and other liquids containing contaminations.

[0002] The invention concerns a device to diminish the risk for clogging of the hydraulic parts in pump stations for sewage water and other heavily polluted liquids.

[0003] A pump station for sewage water comprises a tank with inlets and outlets, that latter(s) from one or several pumps. The sewage water always contains a lot of pollutions such as sludge and elongated objects such as rags which easily clog pumps and pipes. In order to diminish this risk the hydraulic parts of the pumps are designed with large throughlets and the inlets sometimes being provided with cutting means which cut the elongated objects into pieces. An example is shown in the Swedish Patent No 820 5774-6.

[0004] In order to diminish the risk for sludge banks being built up in the pump station it is known practice to arrange special mixers or valves which during certain periods obtain an agitation of the water. An example is shown in the Swedish Patent No 8900597-9.

[0005] Another method which is used to take away elongated objects from the pump inlet is to operate the pump in reverse a short time before each pump start. In this way rags being stuck to the impeller may be flushed away.

[0006] According to the invention is obtained a simple and reliable solution to the above mentioned problems by help of a special shunt lead which is stated in the claims.

[0007] The invention is described more closely below with reference to the enclosed drawing. Here 1 stands for a pump station with inlet 2 and outlet 3 for sewage water. 4 and 5 stand for submersible pumps with inlet 6 and 7 respectively and pressure pipes 8 and 9 respectively 10 stands for a shunt lead having a valve arrangement 11. 12 and 13 finally stand for non-return valves.

[0008] The device according to the invention operates in the following way.

[0009] When the water level in the pump station has risen so much that pumping shall begin, one of the pumps 4 starts to transport the water to the outlet 3. During the initial period of the pumping, some seconds, the valve 11 in the shunt lead is open. This means that a part of the pumped water goes through the shunt lead, downwards through the pressure pipe 9, backwards through the pump 5 and out through its inlet 7. The flow is very strong which means that rags etc being stuck within the pump will be flushed out. The flow will rotate the impeller backwards making objects being wound around the impeller to unwind which makes the cleaning easier. After a predetermined time or when a certain amount of water has passed the valve arrangement 11, the latter is closed and the pumping continues in the normal way. Non-return valves 12 and 13 prevent unintentional back - flow.

[0010] If the incoming water amount is so big that also the other pump 5 needs to be started, this is done in the normal way and no return flow through the other pump 4 takes place. On the other hand, return flow always takes place as soon as one pump starts after both pumps having been stopped. In order to secure cleaning of both pumps the starting order is alternated.

[0011] The valve 11 may, as previously mentioned, be controlled in various ways, manually or automatically, independant of time, amount of flow etc. The invention also includes the use of three or more pump units in the same or adjacent pump stations being provided with shunt leads in the way described above.

Claims

1 A device to diminish the risk for clogging of the hydraulic parts in pumps arranged in a pump station comprising at least two pump units (4), (5) characterized in that it comprises a shunt lead (10) between the outlet pipes (8), (9) from the two pumps (4), (5), the shunt lead being provided with a valve arrangement (11) which keeps the shunt lead open under a certain period when one of the pump starts and at least one of the other pumps does not operate, thus obtaining that a part of the flow from the operating pump (4) goes backwards through the non-operating pump (5), thereby flushing pollutions in its hydraulic part through its inlet (7).

2 A device according to claim 1, characterized in that the valve (11) is time controlled.

3 A device according to claim 1, characterized in that the valve (11) is controlled by the flow.

Drawing