JPS6359037B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for operating any number of sewage pumps installed in parallel, such as mixed flow with guide vanes, axial flow pumps and volute pumps with stevens.

The biggest problem with conventional pumps of this type is clogging when pumping wastewater. Therefore, in order to remove the dirt adhering to the impeller, a method is used in which the pump is operated in a low flow rate region and uses the backflow effect on the pump inlet side.

In such a method, as shown in FIG.
It is not possible to remove foreign matter attached to the steven 4 provided on the discharge side of the impeller 2 which is attached to the casing 3 and housed in the casing 3. Among these foreign substances, fibers are the most difficult to remove.

In order to remove the fibrous material 5 entangled in the impeller 2 and steven 4 as described above, if the fluid flows backward from the discharge side as shown by the arrow as shown in FIG. It was confirmed through experiments that it could be easily removed from Car 2 and Steben 4.

The purpose of the present invention is to eliminate the above-mentioned clogging phenomenon of irrigation pumps and improve their reliability. Close the discharge side merging pipe to form a closed loop with the piping of the parallel pumps, stop some of the parallel pumps, and reverse the discharge flow from the remaining operating pumps to the discharge ports of these stopped pumps. This feature is characterized in that it allows the user to

An embodiment of the present invention will be described below with reference to the drawings.

3 and 4, 10 and 11 are sewage pumps installed in parallel, 12 and 13 are the motors of the pumps 10 and 11, and 14 is the suction confluence pipe 1.
8 is a suction valve provided, 15 is a discharge valve provided in a discharge merging pipe 19, and 16 and 17 are pumps 10 and 1.
These valves are respectively provided in the discharge side branch pipes 20 and 21 of 1. Also, the solid line arrows Qs, Q ₁ ,
Q ₂ and Qd indicate the fluid flow direction in normal forward flow operation, and the dotted arrow shown in FIG. 4 indicates the fluid flow direction in reverse flow operation.

Next, the operating procedure for reverse flow operation of the parallel pump configured as described above will be explained with reference to the time chart shown in FIG.

First, the valves 16 and 17 provided in the branch pipes 20 and 21 of the pumps 10 and 11 are closed, and the suction valve 14 and the discharge valve 15 are closed.
The pumps 10 and 11 are operated via the motors 12 and 13 in an open state. Motors 12 and 13 are the time
After reaching the rated rotation speed (100%N) at t ₁ , the valve 16,
17 is opened appropriately, and this open state is maintained for a certain period of time t ₁ to _{t 2}
When the valves 16, 17 are fully opened at time _t2 , the flow rates of the confluence pipes 18, 19 and the branch pipes 20, 21 become Qs, Qd and _Q11 , _Q21, respectively.
Then, the operation is continued for a certain period of time _t2 to _t3 .

If foreign matter adheres to the impeller and Steinben, reverse flow operation begins at time _t3 . this time t ₃
The time t ₂ to _{t 3} of the forward flow operation may be determined in advance, and the reverse flow operation may be performed periodically. Also pump 10,1
The shaft power of No. 1 may be monitored, and the reverse flow operation may be performed when the shaft power rises above a permissible value.

Next, the valve 16 on the pump 10 side is closed at time _t3 to start backflow operation, the motor 12 is stopped at time _t4 , the discharge valve 15 is closed at time _t5 , and the valve 17 on the pump 11 side is opened. The suction valve 14 is closed at time _t6 . In the state at time _t7 , one pump 11 performs a shut-off operation, and the other pump 10 is stopped.

When the valve 16 on the pump 10 side is opened appropriately from time _t7 , the pump 10 starts to flow backwards, so the flow rate _Q2 becomes a negative flow rate _-Q2 . Then, when the removal of foreign matter attached to the steven and impeller on the pump 10 side is completed, the valve 16 on the pump 10 side is closed at time t ₉ , and the motor 13 is stopped at time t ₁₀ to stop the operation of the pump 11. .

Thereafter, the pump 10 is started in reverse and operated according to the above operation, thereby causing the discharge flow of the pump 10 to flow back to the discharge port of the pump 11, thereby removing foreign matter adhering to the impeller and steven. After the removal of foreign matter from the pump 11 is completed, the pumps 10 and 11 are normally started again to continue operation.

As explained above, according to the present invention, by causing the discharge flow from the operating pump to flow back to the stop pump, foreign matter adhering to the impeller and steven of the stop pump can be removed, clogging phenomenon can be eliminated, and reliability can be improved. can be improved.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing normal flow operation and reverse flow operation of the sewage pump, and FIGS. 3 and 4 show an embodiment of the method of operating the sewage pump according to the present invention, that is, the forward flow FIG. 5 is a system diagram showing operation and backflow operation, and FIG. 5 is a diagram showing a time chart during pump operation according to the present invention. 10, 11...Pump, 14-17...Valve.

Claims (1)

[Claims] 1. For any number of sewage pumps installed in parallel, close the suction side merge pipe and discharge side merge pipe of these parallel pumps to form a closed loop with the piping of the parallel pumps, and operate some of the parallel pumps. A method for operating a sewage pump, characterized in that, at the same time as the pumps are stopped, the discharge flow from the remaining operating pumps is caused to flow back to the discharge ports of the pumps that are out of operation.