Determination of the solids-concentration profile in slurry pipe using radiometric method.
Type:
Presented during:
CEDA Dredging Days 2005 - Dredging: The Extremes, Rotterdam
Authors:
Geus A.M. de, Matousek V., Berg C.H. van den and Vlasblom W.J.
Abstract: Transported coarse particles like medium- and coarse-sand fractions are not uniformly distributed throughout a carrying-liquid flow in a horizontal or inclined slurry pipe. Instead, the particles develop a solids-concentration profile across a pipe cross section with a high local solids-concentration at the bottom of the pipe and a low local solids-concentration at the top of the pipe. The distribution of solids in the slurry flow has a profound effect on friction and wear at the wall of a pipe, therefore the knowledge of solids-concentration profiles is important for an evaluation/optimization of a practical operation of slurry pipelines. A suitable method for the determination of concentration profiles in a large field pipeline connected with a dredge is not yet available. The Laboratory of Dredging Engineering of the Delft University of Technology uses a radiometric density meter as a concentration profiler for the small pipe (diameter of 150 mm) of its test circuit. Recently, the MTI Holland (MTI) and dredging company Jan De Nul (JdN) carried out a field test in which they applied a radiometric concentration profiler to a large slurry pipe. This paper discusses an application of the radiometric method in both a small laboratory- pipe and a large field-pipe. The paper brings the following information:
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Analysis of the principles of the measuring method;
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Report on the improvements made on the laboratory meter;
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Analysis of the concentration profiles from the lab-tests and the MTI & JdN field tests;
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Definition of the turbulent-dispersion coefficient for sand-slurry flows in small and large pipes;
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Recommendations regarding the future use of the measuring method in field pipelines.
Keywords: radiometric density measurement, turbulent dispersion, solids distribution, mixture flow