Submersible sewage pump is the abbreviation of submersible sewage pump. On the basis of submersible pump, the channel adopts anti-clogging design, which is used for primary lifting, intermediate lifting and sludge return. Mainly used in municipal engineering, building construction, industrial sewage and sewage treatment occasions, to discharge sewage, waste water and rainwater containing solids and long fibers.
The submersible sewage pump has simple installation conditions and a large flow coverage. It is one of the most commonly used lifting equipment in water treatment projects, especially in small and medium-sized projects. There are mainly two common installation methods for submersible sewage pumps: coupled installation and mobile installation.
Coupling installation is to connect the pump to the pipeline through a couple, and it is convenient to disconnect the pump from the outlet pipeline. The pump can be lifted by the lifting device during maintenance. Coupling installation is suitable for submersible sewage pumps of various specifications and is the most commonly used installation method for submersible sewage pumps. The couple is supplied as a complete set by the equipment manufacturer.
Mobile installation means that the pump outlet pipeline is directly connected to the surface of the water through a hose, and the submersible sewage pump is self-reset at the bottom of the pool or hung on the lifting device through iron chains. The mobile installation does not require a couple and the bottom of the pool to be fixed, so it is easy to move, and the pipeline can be lifted together during maintenance. At the same time, due to the installation method, it is difficult to bear a large torque, which is only suitable for small submersible pumps.
After the selection is confirmed, the manufacturer of the submersible sewage pump will provide a drawing of the installation conditions, and the designer needs to be able to read the meaning of each size and symbol. Examples are as follows:
(1) The lowest operating liquid level
For pumps above 11kW, the motor cooling system can be selected to cool the pump. If the cooling system is not selected, the pumped medium will directly cool the motor. The two different cooling methods correspond to different minimum liquid levels. The direct cooling method requires a higher liquid level than the method with a cooling system.
In the installation condition diagram provided by the manufacturer, a solid triangle "▼" and a hollow triangle "▽" are used to distinguish, where "▼" means with cooling system, and "▽" means without cooling system.
In the installation condition diagram of the above case, with the cooling system, the effective minimum liquid level is 570mm from the bottom of the coupling device, and without the cooling system, the distance is 785mm. That is, the effective liquid level can be lowered by 215mm when there is a cooling system.
(2) Plane opening and positioning
When the submersible pump is installed in coupling mode, the minimum installation size of the submersible pump should be considered for the opening of the plane. The A-direction view in the case shows the size of the smallest mounting hole of the pump, which is 1000×700mm.
When positioning, the edge of the pool where the guide rod is installed is the reference line. This is because the positioning of the submersible sewage pump is completed by the guide rod connected with the coupling device, and the position of the guide rod is determined by the side of the pool. When positioning the bolts of the couple base, it is also necessary to take the edge of the pool as the reference line. According to the above case, first determine the position of the bolt hole 253mm from the edge of the pool, and then determine the position of the other two bolt holes through the bolt hole spacing of 350mm.
The most important dimensions finally reflected in the drawings are: the position and size of the top plane opening, and the position and specifications of the embedded anchor screws at the bottom (usually reserved holes are used for post-pouring concrete design).
The top guide rod is usually fixed by means of expansion bolts.
(3) Electrical protection measures
Since the submersible sewage pump is submersible, it may be damaged by water leakage, etc., which needs to be prevented. Take a submersible sewage pump manufacturer as an example, the measures adopted are:
Pumps below 7.5kW are equipped with motor winding overheating protection elements and water leakage probes. Pumps of 11kW and above are equipped with motor winding overheating protection elements, float switches, and water leakage probes. For pumps of 30kW and above, a water leakage probe is added in the upper end cover of the motor.
Among them, the overheating protection element is placed in the stator winding of the motor. Under abnormal operating conditions, when the winding stably reaches the set value of the overheating protection element, the electric cabinet overheating protection device stops the motor.
The water leakage probe is used for water leakage detection. After water enters the motor side, the electric control cabinet will alarm and stop. The float switch is used to detect the failure of the mechanical seal on the motor side and whether the motor cavity has water ingress. After detecting the water ingress, the electric control cabinet will alarm and stop.
In the electrical installation of the submersible sewage pump, it is necessary to design the electric control cabinet according to the selection conditions and the electrical requirements feedback from the manufacturer to achieve the protection effect.
