Submersible sewage pumps belong to a type of non clogging pump and come in various forms, such as submersible and dry. Currently, the most common submersible sewage pump is the submersible sewage pump, while rare dry sewage pumps include horizontal and vertical sewage pumps. Important for transporting urban sewage, feces or liquids containing fibers. The medium containing solid particles such as paper scraps is usually transported at a temperature not exceeding 80 ℃. Because the guaranteed medium contains fibers that are prone to entanglement or clumping. Therefore, the flow channel of this type of pump is prone to blockage. Once the pump is blocked, it will be unable to function properly and even destroy the motor, resulting in poor drainage. It has a significant impact on urban life and environmental protection.
Therefore, anti clogging and reliability are important factors for the quality of sewage pumps. Like other pumps, the impeller and pressure chamber are the two central components of the sewage pump. The quality of its performance represents the quality of the pump performance. The anti clogging performance, effectiveness, cavitation performance, and anti abrasion performance of the sewage pump are mainly guaranteed by the two components of the vane pump and the pressure chamber.
1. Impeller construction type:
The construction of impellers can be divided into four categories: blade type (open, closed), swirl type, channel type, and spiral centrifugal type (including single channel and double channel)
The production of open and semi open impellers is inconvenient. When blockages form inside the impeller, it can be easily cleaned and repaired. However, during temporary operation, the erosion of particles can increase the gap between the blades and the side wall of the pressurized water chamber, resulting in a decrease in efficiency. And increasing the gap will damage the pressure difference spread on the blades. Not only does a small amount of vortex loss occur, but it also increases the axial force of the pump. At the same time, due to the increased gap, the stability of the liquid flow in the channel is damaged, causing the pump to vibrate. This type of impeller is not easy to transport media containing large particles and long fibers. In terms of performance, this type of impeller has low efficiency, with high efficiency about 92% of that of ordinary closed impellers, and a relatively smooth head curve.
Swirl impeller:
The pump with this type of impeller is used because the impeller is partially or completely retracted from the pressure chamber flow channel. So the non obstructive performance is good, and the passage of particles and long fibers is stronger. The particles move in the pressurized water chamber and are pushed to rest by the vortex generated by the rotation of the impeller. Suspended particles do not generate energy on their own, but only replace energy with the liquid in the flow channel. During the activity, suspended particles or long fibers do not come into contact with the blades, resulting in less wear and tear on the blades. There is no increase in clearance due to abrasion, and there is no significant decrease in power efficiency during temporary operation. Pumps with this type of impeller are suitable for pumping media containing large particles and long fibers. In terms of performance, the efficiency of this impeller is relatively low, only about 70% of that of a regular closed impeller, and the head curve is relatively smooth.
Closed impeller:
The normal efficiency of this type of impeller is relatively high. And during temporary operation, the situation is relatively stable. The pump with this type of impeller has less axial force and can be equipped with auxiliary blades on the front and rear cover plates. The auxiliary blades on the front cover plate can increase the loss of vortex at the impeller outlet and the wear of particles on the sealing ring. The secondary blades on the rear cover plate not only serve to balance the axial force, but also prevent suspended particles from entering the mechanical seal chamber and providing cover for the mechanical seal. However, this type of impeller has poor non clogging performance, is easy to wrap, and is not suitable for pumping untreated sewage media containing large particles (long fibers).
Flow channel impeller:
This type of impeller belongs to bladeless impellers, and the impeller flow channel is a tortuous flow channel from the outlet to the outlet. So it is suitable for pumping media containing large particles and long fibers. Good anti blocking performance. In terms of performance, this type of impeller has high efficiency and is not much different from ordinary closed impellers, but the head curve of the pump with this type of impeller drops sharply. The power curve is relatively bumpy, making it less prone to over power issues. However, the cavitation performance of this type of impeller is not as good as that of ordinary closed impellers, especially suitable for use in pumps with pressure outlets.
Spiral centrifugal impeller:
The blades of this type of impeller are twisted spiral blades that extend axially from the suction port on the conical hub body. This type of impeller pump serves as both a backup volumetric pump and a centrifugal pump. Suspended particles expire in the flow of the blades and do not collide with any part of the pump, making it non-destructive. The damage to the insured item is minimal. Due to the pushing effect of the spiral, suspended particles have strong passability, so pumps with this type of impeller are suitable for pumping media containing large particles and long fibers, as well as high concentration media. It has significant characteristics in places where there are strict requirements for damage to the guaranteed medium.
In terms of performance, the pump has a steep head curve and a relatively smooth power curve.
The pressure chamber adopted by sewage pumps is a snail shell, and radial guide vanes or flow channel guide vanes are often used in built-in submersible pumps. There are three types of snail shells: spiral, ring, and intermediate. On the basis of the spiral volute, it is not necessary to use it in the sewage pump. Circular pressurized water chambers are commonly used in small sewage pumps due to their simple construction and inconvenient production. But due to the emergence of intermediate (semi spiral) pressure chambers, the scale of application of annular pressure chambers is gradually decreasing. Due to the combination of high efficiency of spiral and high permeability of annular pressure chambers, the intermediate type pressure chamber.
2. The five major advantages of submersible sewage pumps:
(1) The structure of the sewage pump is relatively compact and occupies a small area. Submersible sewage pumps can be directly installed in sewage tanks due to their underwater operation, without the need to build specialized pump rooms for installing pumps and machines, which can save a lot of land and infrastructure costs.
(2) The installation and maintenance of sewage pumps are very convenient. Small submersible sewage pumps can be freely installed, while large submersible sewage pumps are generally equipped with automatic coupling devices for automatic installation, making installation and maintenance quite convenient.
(3) The continuous operation time of the sewage pump is relatively long. Submersible sewage pumps, due to their coaxial pump and motor, short shaft, and lightweight rotating components, bear relatively small radial loads on their bearings and have a much longer lifespan than regular pumps.
(4) There are no issues such as cavitation damage or water injection during the operation of the sewage pump. Especially the latter point has brought great convenience to the operators.
(5) The environmental performance of the sewage pump is good. Low vibration noise, low motor temperature rise, and no pollution to the environment.
