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Sewage pump and slurry pump efficiency comparison recommendations
In some literature, it is commonly mentioned that sewage pumps and slurry pumps exhibit relatively high water efficiency, with some even approaching the performance of water pumps. Based on this, I would like to share my perspectives:
(1) With the continuous advancement in theoretical research and the accumulation of experimental data, especially with the application of two-phase flow theory, it is inevitable that the efficiency of sewage and slurry pumps will keep improving over time.
(2) Ordinary water pumps are designed for maximum efficiency, meaning their hydraulic structure parameters are optimized for peak performance. However, for sewage pumps and slurry pumps, which have special requirements, their efficiency cannot be directly compared to that of general water pumps. This comparison should be based on contemporary standards rather than individual design capabilities.
(3) A key reason why the efficiency of sewage and slurry pumps is generally lower is due to the widened flow channels. The degree of widening significantly affects efficiency. Therefore, comparing the efficiency of different sewage or slurry pumps without considering capacity (Q, H, n) is not meaningful.
(4) The widened runner in sewage pumps is designed to prevent clogging, which typically results in lower efficiency compared to secondary sewage pumps.
According to statistical data on sewage pumps with φ/DS ranging from 0.6 to 0.8 and Q less than 600 m³/h, the author proposed an efficiency formula under these conditions [1]:
η = 0.78 - (6.74Q)^(-0.32) - 0.29 × (0.32 - lg 0.013 ns)^2
Where Q is the flow rate in m³/h, φ is the pump size in mm.
(5) In mud pumps, the runner is often enlarged to reduce the flow velocity of the two-phase mixture, thus minimizing wear. As a result, strong abrasive slurry pumps usually have lower efficiency compared to those handling less abrasive materials. For example, Zigong Industrial Pump Co., Ltd. produces NG and ND pumps for highly abrasive slurry, while NQ pumps are used for lighter slurries.
(6) It is recommended that when specifying the efficiency of sewage and slurry pumps, the minimum passing size should also be provided to allow for more accurate comparisons of pump design quality.
It is also suggested that an experimental relationship between η = f(Q, ns, φ) should be established for sewage and slurry pumps to better understand and optimize their performance.