Le système de pompage air-lift et la remontée des nodules polymétalliques marins

Air-lift pumping and raising of polymetal nodules from the bottom of the sea

Université Catholique de Louvain Département Thermodynamique et Turbomachines

Abstract

Basic principles for the design of air-lift pumps and their applications to the pumping of polymetallic nodules from the floor of the oceans are presented in two sections. The first section discusses the pumping of liquids. The relationship between the liquid and gas flow-rates is deduced from the momentum equation of the mixture and by using the Zuber and Findlay expression for the void fraction. The total efficiency of the pump is divided into two factors : one is the isothermal efficiency of the compressor, whereas the other is related to the two-phase flow in the pipe. Results of calculations are presented and general design rules are deduced concerning submergence ratio, tube diameter, type of injector and air flow-rate. In the second section, on the pumping of solid elements by means of the air-lift pump, the momentum equation of the three-phase flow is written, and expressions are given for both void fraction and friction pressure drop. Typical results of the solid versus gas flow-rate and efficiency versus gas flow-rate calculations are presented.