Improvements relating to centrifugal pumps for non-homogeneous media

摘要

653,161. Centrifugal pumps. SULZER FRERES SOC. ANON. Oct. 19, 1948, No. 27140. Convention date, Oct. 25, 1947. '[Class 110(i)] A centrifugal pump for non-homogeneous media, i.e. mixtures of liquid and either or both solids or gases, is provided with means for imparting to the medium in the centripetal field of the impeller a circulation about an axis substantially parallel with the impeller axis, in such a way that the intensity of the circulation increases as the rate of delivery decreases. According to one arrangement, auxiliary blades 7, Figs 3 and 4, are placed between the main impeller blades 12, the leading surfaces 8 being inclined forwards in the direction of rotation. In addition or alternatively, the outer ends of the main blades may be chamfered so as to slope away towards the rear, as at 14, or the leading surfaces 10 may be curved forwards in the direction of rotation in the vicinity of the impeller periphery. In the construction shown in Fig. 1, the impeller has not more than four blades, the axial width of which is greater at the outlet than at the inlet. Preferably. the cross-sectional areas of the impeller channels, measured in a surface normal to the meridional component of the velocity of flow, is at least three times as great at the outlet as at the inlet, and the radial distance of the outlet end of each blade from the impeller axis does not exceed 2.7 times that of the inlet end. A further arrangement, which may be used by itself or in conjunction with any of the other arrangements, comprises stationary guide blades 17 which protude into the impeller eve and are spaced from the impeller hub by only a small clearance.