In addition to economic considerations, the two main considerations for dredge pump operation are that the deposits in the pump are not settling and the amount of wear in the pump is minimal due to flow operations. The key design parameters to remember to meet the main requirements are installation type, critical flow, total discharge head and pump design material.
Know your slurry type:
Before continuing to estimate the design parameters of your dredge pump, a very critical step is to become familiar with the materials that need to be transported. Therefore, estimating the pH and temperature of the slurry, the specific gravity of the slurry, and the concentration of solids in the slurry are the first critical steps toward the “your” ideal pump selection.
Critical flow estimate:
The critical flow rate is the transition flow rate between the laminar and turbulent flows and is calculated based on the particle diameter (the size of the slurry particles), the solids concentration in the slurry, and the tube diameter. For minimum sedimentation of the sediment, the actual dredge pump flow rate of your "pump" should be higher than the calculated critical flow rate for your application. However, it is important to carefully select the pump flow as the increase in flow will increase the wear or wear of the pump material, thus shortening the life of the pump. Therefore, in order to achieve uninterrupted performance and extended service life, the pump flow should be optimized.
Unloading head estimate:
The total discharge head is a combination of the static head (the actual elevation difference between the slurry source surface and the discharge port) and the frictional losses in the pump. In addition to relying on pump geometry (pipe length, valve or bend), friction losses are also affected by pipe roughness, flow rate and slurry concentration (or percentage of solids in the mixture). Friction losses increase with increasing pipe length, slurry specific gravity, slurry concentration, or slurry flow rate. The pump selection procedure requires that the discharge head of your dredge pump be higher than the calculated total discharge head. On the other hand, it is important to note that the discharge head should be kept as low as possible to reduce pump wear due to slurry flow.
The power consumption of the dredge pump is estimated from the discharge head, the flow rate and the specific gravity of the pumped slurry. It is important to verify that the rated power of the selected pump is above the calculated power consumption after taking into account reasonable changes in operating conditions.
Typical materials used to construct dredge pumps are cast iron, stainless steel and high chromium steel. Some dredge pumps are lined to better address slurry wear problems. Some of the elastomers used in the lining material are natural rubber, polyurethane or neoprene. The choice of lining material depends on the operating temperature, the pH of the slurry, and the presence of the particular abrasive fluid used during the dredging process.