A high-pressure visual flow loop for hydrate blockage detection and observation.

Abstract

More than 65% of the worldwide natural gas is transported through pipelines. Gas hydrate formation and blockage in the pipeline are commonly encountered, causing significant problems in safe and efficient transportation. Yet the instrument simulating the high-pressure multiphase flow and demonstrating the hydrate blocking behavior at flowing conditions is not available. In this work, a high-pressure visual flow loop is developed to detect and observe the hydrate nucleation, growth, and deposition during the multiphase flow. The pressure limit is designed to be 8 MPa, and the temperature can go down to -20 °C. This device allows a direct observation of the gas-liquid flow regime during transportation; investigations on the initiation and evolution of hydrate blockage in the dead-leg section, U-shaped region, and rising pipes are now possible. Sensors are distributed along the pipelines to detect the pressure and temperature change; the differential pressure is used to effectively detect the degree of hydrate blockage, which increases upon hydrate formation. The visual flow loop could also help examine the effect of shut-down and restart of the pump on the flow behavior. The system has been verified feasible demonstrating the flow behavior and predict hydrate blockage. The developed device would help understand the mechanism of hydrate blockage in the transportation pipelines and provide guidance to efficiently avoid such problems.