51314-4325-Evaluation of Sand Erosion Measurement Techniques for Model Validation in Elbows for Low Liquid Loading and Annular Flow Conditions

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Product Number: 51314-4325-SG

ISBN: 4325 2014 CP

Author: Ronald Vieira

Publication Date: 2014

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Erosion is a complex process that is affected by numerous factors which can significantly affect the damage it causes. Detection of erosion as it progresses is also difficult and operators rarely have a good measure of the internal condition of the pipes and fittings in their systems. This makes erosion management difficult especially for those unfamiliar with the manner in which erosion occurs. This work discusses measuring erosion in standard 76.2 mm (3-inch) elbows for evaluation of models for low-liquid loading and annular flow conditions that occur frequently in gas productions conditions. Erosion data was collected using three different techniques: an erosion test cell with an elbow specimen intrusive electrical resistance (ER) probes and non-intrusive ultrasonic technique with a modified data acquisition algorithm. A CPVC test cell was used to observe erosion patterns and measure metal loss of an aluminum specimen. The electrical resistance probe was flush mounted in the outer bend at 45 degrees of a stainless steel elbow. The ultrasonic transducers were permanently mounted at 16 locations on the outside bend of a stainless steel elbow which enables the measurement of thickness loss patterns over a broad area of the elbow surface area under different operating conditions. Experimental conditions were varied in order to gain a firm understanding of the ER probe's and ultrasonic transducer's accuracies for measuring metal loss as superficial gas and liquid velocities sand size and flow orientation are varied. Erosion experiments were conducted in a large scale multiphase flow loop with varying gas (air) and liquid (water) velocities generating low-liquid loading and annular conditions. Particle sizes used in the experiments were 150 and 300 microns with 1% concentration by weight (based on liquid rate). The experiments were performed in the upward vertical and horizontal orientation. The location of the maximum measured erosion for vertical and horizontal annular flows under low pressure and high gas flow rates is on the outer radius of the bend near the 45 degree position. Significant differences were observed between ER probes and ultrasonic transducers trends of maximum erosion values. Furthermore based on the experimental results a mechanistic model that was previously developed has been improved to predict erosion in gas dominant flow regimes considering the effects of sand particle distribution and particles velocities in gas liquid-flows.