The Theoretical Analysis And Experimental Comparison On The Air-lift And Gas-injection Pump

The air-lift pump is a machine of conveying fluid which takes the compressed air as working medium, it can pump and transport fluid or slurry. Its structure is very simple comparing with other types of pumps, furthermore, the air-lift pump has many advantages of itself, it hasn't moving components, the questions of lubrication and friction could not appear consequently. So speaking from theory, the expenses of equipment maintenance are very low, and the pump's reliability is high. The application of air-lift pump is very wide in oil production engineering,deep-sea mining and desilting works.But also the air-lift pump has some limitations, the relative low efficiency is the primal problem. To solve this problem, The lifting solids capability and the efficiency of the air-lift pump and the gas-injection have been studied from this paper, The force of the solids in the pipe has been analysed by combining the theory. The models of pressure loss has been established basing on the three-phase flow, and the model of efficiency has been established by the momentum theorem and energy conservation.Basing on the conditions of the laboratory and the project, a small-sized air-lift system which selected normal riversand(diameter 1~5mm) as the working medium has been established. In order to improve the accuracy of solid and water flow rate, we have made an creative design on the testing device. Experiment shows that, the submergence ratio and air input are the very important factors in effecting the characteristic curve of ail-lift pump. The more the submergence ratio, the more the solid output and efficiency. There has the optimum air input making the solid output and efficiency to the peak. We design the parameters of structure about air-lift pump, the gas-injection pump uses the structure of annular injector, at low air input, the efficiency of gas-injection pump is not higher than air-lift pump, while at high air input, the efficiency of gas-injection pump is more higher than air-lift pump, when the air input is optimum, the efficiency of gas-injection pump is 2.75 times higher than air-lift pump.In summary, the efficiency of gas-injection pump is higher than air-lift pump , this paper has a guiding significance to deep-sea mining and desilting works and so on.