Abstract: Particles are separated from a source viscoplastic fluid by flowing streams of the viscoplastic fluid and a destination fluid in parallel streamed relationship inside a rotating cylindrical annulus by using baffles to introduce each fluid independently at an inlet lower end of the annulus and for separating the upper streams consisting of an un-yielded source and destination flow proximate the radially innermost side of the annulus, a bulk axial flow in a more central region and a yielded layer destination flow adjacent the radial outermost side of the annulus which contains the particles that have separated. Inlet and outlet baffles are provided at each end of the vertically oriented device to maintain the flows discrete on entry and to maintain the separated flows discrete on exit so as to facilitate removal of the component flows from the fractionator.

Abstract: Particles are separated from a source viscoplastic fluid by flowing streams of the viscoplastic fluid and a destination fluid in parallel streamed relationship inside a rotating cylindrical annulus (FIG. 16 (106, 102b) by using baffles (112, 114) to introduce each fluid independently at an inlet lower end of the annulus and for separating the upper streams consisting of an un-yielded source and destination flow proximate the radially innermost side of the annulus, a bulk axial flow in a more central region and a yielded layer destination flow adjacent the radial outermost side of the annulus which contains the particles that have separated. Inlet and outlet baffles are provided at each end of the vertically oriented device to maintain the flows discrete on entry and to maintain the separated flows discrete on exit so as to facilitate removal of the component flows from the fractionator. The flow is maintained as laminar Poiseuille flow by adjusting the flow rates of the source and destination fluids.

Abstract: A method and system for determining trace oversize contaminant particles in a paper-making pulp employs a screen assembly having a screen housing with a screen mounted therein, and ports for introduction of aqueous pulp and rinsing and flushing fluids, and for withdrawal of screened aqueous pulp, the screen housing has no port designated for the sole purpose of removing accumulated contaminant particles from the screen housing; instead the port employed for introduction of aqueous pulp and which may also be employed for introduction of rinsing fluid to the housing, is employed as the flushing port for removal of contaminant particles.

Abstract: A method and system for determining trace oversize contaminant particles in a paper-making pulp employs a screen assembly having a screen housing with a screen mounted therein, and ports for introduction of aqueous pulp and rinsing and flushing fluids, and for withdrawal of screened aqueous pulp, the screen housing has no port designated for the sole purpose of removing accumulated contaminant particles from the screen housing; instead the port employed for introduction. of aqueous pulp and which may also be employed for introduction of rinsing fluid to the housing, is employed as the flushing port for removal of contaminant particles.