High-pressure high-temperature coal slurry centrifugal pump and let-down turbine

摘要

A two-stage, high-pressure centrifugal pump comprises a pump housing and at least one pair of external inlets and outlets for charging and discharging each stage of the pump. The inlets and outlets are located through the periphery of the pump for allowing on-line maintenance. Prerotator vanes are located along the interior wall of the pump housing and convey a fluid from the external inlet to the impeller while reducing the inlet relative velocity at the impeller inlet and primarily at the impeller inlet tip. A pair of face-to-face impellers located along the pump shaft are designed to increase the fluid velocity while transferring fluid to a vaneless radial diffuser. The diffuser then decreases fluid velocity and increases fluid pressure due to increasing diffuser volume. From the diffuser the fluid is conveyed into a fold-over volute which is likewise designed to increase fluid pressure while additionally eliminating flow patterns which would increase losses within the system. A replaceable cutwater is interposed between the diffuser and the volute to channel fluid into the volute and, finally, a hydrostatic slurry seal is coaxially located along the pump shaft so as to prevent leakage of the primary fluid from the high-pressure pump interior to the atmospheric pump exterior. Upon reversing the fluid flow, the pump discharge pipe or external outlet becomes turbine intake 102 and pump inlet volute 14 becomes the turbine radial discharge scroll 112. Discharge scroll 112 is then connected with cross-over duct 114 and leads via a second turbine intake 102 into the second stage of the let-down turbine 100.