Method and apparatus for providing oscillating contaminant-removal stream

摘要

For removal of the contaminant deposits from a surface such as a tube sheet of a vertical tube heat exchanger, as in a nuclear steam generator, having plural spaced heat exchange tubes connected to the tube sheet, a lance is radially moved along the tube sheet between parallel rows of tubes. The lance carries a nozzle for ejecting a stream of high pressure cleaning fluid toward the sludge deposits, the nozzle acting cyclically to sweep the stream throughout a range of directions centered about the nozzle axis. The nozzle may include diverting streams for deflecting the cleaning fluid stream, with the diverting streams either being generated by a fluidic oscillator or being fed back from the outlet portion of the nozzle. Alternatively, pivoting vane means may be provided in the nozzle to divert the cleaning fluid stream.