Sewage pump structure

Impeller

The sewage pump shares similarities with other pumps, as both rely on two essential elements: the impeller and the pressure chamber. These two components not only determine the overall performance of the sewage pump but also reflect its advantages and disadvantages. The pump's effectiveness in preventing clogging, its level of efficiency, and its ability to resist cavitation are key criteria for evaluating its performance. Moreover, the anti-abrasion capability of the sewage pump heavily relies on the vane pump and the pressurized water chamber. Now let's delve into a more detailed explanation of these aspects.

Impeller structure type:

The impeller structure can be broadly classified into four categories- blade type, swirl type, flow channel type, and spiral centrifugal type. The blade type impeller can be further classified into open and closed types. The swirl type impeller is designed to create a vortex in the fluid medium to improve the mixing process. The flow channel type impeller can be further classified into single and double flow channel type. The spiral centrifugal type impeller is designed to generate a high centrifugal force to extract solid particles from the fluid medium.

The open semi-open impeller boasts easy manufacturing processes, allowing for convenient cleaning and repairs when blockages occur. However, prolonged use leads to increased gaps between the blades and the pressurized water chamber's side wall due to particle abrasion. This results in reduced efficiency and disrupts the pressure difference distribution on the blades. The consequences are twofold: the generation of significant vortex losses and an increase in the axial force exerted on the pump. Moreover, the enlarged gaps destroy the stability of liquid flow within the channel, causing pump vibrations. Consequently, this type of impeller is unsuitable for transporting media with large particles and long fibers. In terms of performance, it exhibits lower efficiency compared to an ordinary closed impeller, with the highest efficiency reaching only about 92% of that achieved by the latter. Additionally, this impeller's head curve is relatively flat.

Swirl impeller:

This type of pump features an impeller that can be partially or fully retracted from the pressure chamber's flow passage. This unique design provides excellent non-clogging performance and high particle and long fiber passing abilities. The impeller's rotation generates a vortex that drives suspended particles through the pressurized water chamber. These particles do not create energy themselves but exchange it with the liquid flowing in the channel. The impeller's blades are less prone to wear and tear as suspended particles or long fibers do not come into contact with them during the flow process. This means that the blades do not experience any enlargement of gaps due to abrasion. As a result, the pump maintains its efficiency even after long-term operation. This impeller pump is ideal for pumping mediums with large particles and long fibers.

The impeller's performance efficiency is relatively low, approximately 70% compared to a regular closed impeller. Additionally, its head curve is relatively flat. To generate highly similar content based on the original information, the impeller's efficiency is significantly less as it only achieves about 70% of the efficiency seen in a standard closed impeller. Moreover, the head curve remains relatively flat in comparison.

Closed impeller:

Generally, this impeller type exhibits higher efficiency and maintains relatively stable performance during long-term operation. It generates minimal axial force, allowing for the incorporation of auxiliary vanes on both the front and rear cover plates. The presence of auxiliary vanes on the front cover aids in reducing vortex loss at the impeller inlet and protects the seal ring from particle wear. On the other hand, the auxiliary vane on the back cover serves a dual purpose: balancing the axial force and preventing the entry of suspended particles into the mechanical seal cavity, thus safeguarding the mechanical seal. However, despite these advantages, this impeller type has limited ability to handle clogging and is prone to entanglement. Therefore, it is not suitable for pumping untreated sewage media containing large particles or long fibers.