심해저 망간단괴 시험집광기 혼합식 채집장치의 소형 물제트 펌프 개발사례

Abstract

A compact size pump of mixed flow type was developed in order to supply water flow to water-jet nozzles of hydraulic lifter of test miner for collecting deep-seabed manganese nodules. Required specifications such as flow rate, head loss and rotation speed were determined or calculated as 16m, 6.87 m3/min, 2930 rpm, respectively. Since the specific speed was calculated as 958 [m, m3/min, rpm], we determined a mixed flow type pump. Under these specifications, we designed the mixed flow type pump with 3 vanes of impeller, 5 vanes of guide vane and IGV (Inlet Guide Vane). The vane was designed by using In-house design calculation sheet of KJI(Keumjung Ind. Co. Ltd). The lubrication oil of bearing housing was connected with pressure-compensator in order to keep the pressure difference to be constant between the oil and ambient fluid. Thordon bearing was chosen as radial bearing located in the center of the stator casing. 18.4 m in head and 73.8% in efficiency was measured at 6.87 m3/min and 2930 rpm in Factory Acceptance Test. 6.15 m3/min in flow rate was measured at 2610 rpm in 1st operation test of test miner. The reason of 10% performance reduction in flow rate was found that we couldn't increase the rotating speed because of reaching at maximum setting value for pressure of hydraulic motor. In order to overcome this problem, we attached guide vane for reducing the pressure drop of water flow and we will replace the 23 cc hydraulic motor with the lager displacement of motor about 30 cc for increasing the power of motor.