Partial Blockage Detection in Pipelines by Modified Reconstructive Method of Characteristics Technique

Abstract

Blockage detection using transient analysis has emerged as a promising technique because it requires measurements at only one location. This study proposes a modified reconstructive method of characteristics (RMOC) technique suitable for detecting multiple partial discrete and extended blockages in elastic and viscoelastic conduits. It is proposed that evaluating the steady-state (SS) head in a pipe can determine the discrete blockage parameters, and the pipe area reconstruction can be employed to estimate the multiple extended blockages. The pipe is discretized into several finite cells, and characteristic equations are derived for the inverse computation of SS flow parameters. The blockage is assumed to be at the interface of the cells. The blockage location and size predictions are more accurate than those using the techniques that use multiple signal cycles, because the short-duration signal (half-wave cycle) is used. The friction factor need not be known a priori in discrete blockage detection, and the need for the assumption of regular geometric blockages is eliminated in extended blockages. Prior knowledge of the number of blockages and the upstream reservoir boundary conditions also is not required. The paper discussed the significance of the inclusion of viscoelasticity in the model. The numerical and experimental validations showed excellent consistency between the actual and estimated fault parameters. The error in the estimation of the size of a discrete blockage from experimental data was less than 5% in all cases except one, which had an error of 8%. A sensitivity analysis was performed to determine the influence of the system parameters on the results.