Selection of circulation pump for the absorption tower in a 300,000-ton acid production plant

Thread Content

Our factory’s new ASIA Bank-funded sulfuric acid production system has a design capacity of 330,000 tons. The dry absorption process employs the most advanced low-level, high-efficiency dry absorption technology available in China at that time; the first and second absorption towers share a circulation tank, acid pump, and acid cooler. Originally, a Lewis pump was chosen; however, due to financial constraints at the time, two 750 m3/h Dalian Great Wall pumps were used instead. When these two pumps operated simultaneously, excessive vibration occurred, so it became necessary to use them one at a time! The amount of acid in the absorber tower was consistently insufficient. In March 2007, the workshop submitted a report requesting the use of larger pumps, suggesting the Lewis pump; however, since the Lewis pump is an imported device, its delivery time is long. In April 2007, a Kunming Jiahe pump was installed, and its performance has been satisfactory. The Lewis pumps arrived in June 2007, and it was decided at that time to replace them with Lewis pumps during the annual maintenance. On January 3, 2008, the Lewis pump was installed and tested. The main problems were that the opening degree of the outlet butterfly valve was too low (below 20%), the pump vibrated severely, the motor current reached 580A, and the acid flow rate was close to 1200 m3/h. Due to the high vibration of the pump, in order not to affect operation, it was necessary to replace it with a Xihe pump. An analysis meeting was held in the workshop this morning; it is believed that the main reason is that the pump was selected in a too conservative manner, with high head and flow rates, resulting in the pump not operating near its highest efficiency point. I would like to ask my colleagues here: for the aforementioned low-energy, high-efficiency dry absorption process, the head required by the pump in the absorption tower is only 18 meters; choosing a pump with a head of 22 meters should be sufficient. I’m wondering what head value is typically used when selecting pumps for handling concentrated acid in absorption towers in this industry?