Selection of concentrated acid pumps and calculation of pipeline resistance

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When selecting a pump for concentrated acids, it is something most people are familiar with; the key aspects are determining the head and flow rate. The relationship between headroom and flow rate can be illustrated by the range of a cannon and the power of its projectiles; no matter how powerful the projectiles are, it’s useless if their range is insufficient. It is evident that in the industry, the selection of concentrated acid pumps is often based on experience, resulting in situations where overpowered pumps are used for tasks that require less power. I remember that when selecting an imported Lewis pump, in order to determine the pump’s head, I went to the trouble of calculating the resistance in the cathodic protection pipeline as well. Even though the calculations were done using Excel, it was still quite cumbersome. The resulting resistance loss in the pipeline (including head loss and kinetic energy loss) was not high, at only 18 meters (with the dry suction tower positioned at a lower level). Taking into account the influence of the pipeline electrodes for cathodic protection, the pump head was promptly determined to be 22 meters, and a report was submitted to higher-level management. The higher-level management decided that, since imported pumps were being purchased, it was necessary to leave some margin; therefore, the head was set at 27 meters and the flow rate was increased to 1600 m3/h. When the Lewis pump arrived at the site, the workshop leaders and colleagues were very pleased; finally they had good equipment, and indeed the Lewis pump also had an attractive appearance! However, after the pump was installed and started up, it was found that the pump motor was overloaded, the outlet valve of the pump was open only slightly, and vibration occurred as well. In response to the above situation, it was immediately suggested to cut the impeller, but the management disagreed, arguing that if we cut the impeller on our own for the inlet pump, it would be difficult to find a supplier in case problems arise later. What should I do? It was ultimately decided to install 2 reducers at the pump outlet to increase resistance. After the aforementioned modifications were made, the motor overload during pump operation improved significantly, and as the pump ran for longer periods of time, its current gradually decreased, leading to more stable operation. Through the above practices, it became clear in no time that the selection of concentrated acid pumps in China relies mainly on experience; no wonder the impellers often get damaged!