Impact Wear Prediction And Wall Thickness Monitoring Of The Elbow Region In The Oil-Coal Slurry Pipeline

Wear of pipelines transporting fluid under high temperature, high pressure and high solid content rate is often very serious. Wear prediction and thickness monitoring are essential for safety assessment of such pipelines.Numerical flow simulation was done by Fluent for elbows with 7 different kinds of diameter and 8 kinds of bending radius to diameter ratio which are used to transport coal-oil slurry in coal liquefying industry. The velocity field was obtained under turbulent flow. Wear model was inserted into Fluent by secondary development to predict the erosion at the elbow region. It reveals that there are remarkable differences of wear position and wear value with different ratios of bending radius to diameter. The maximum wear values decrease with the increase of ratios of bending radius to diameter for the elbow with the same diameter. Elbows with the ratio of bending radius to diameter from 4 to 6 are recommended for economic reason.Waveguide with the same material was suggested to be vertically welded to the pipe thickness monitoring position with full penetration, in which the waveguide is cooled by water to the temperature that make thickness monitoring possible for pipes under high temperature and high pressure with conventional ultrasonic sensor and coupling medium. Take stainless steel as example, waveguides were welded to circular flat plate, straight pipe and elbow for thickness measuring. The experiment results are in agreement with the specimen thicknesses. Water jacket was designed to cool the waveguide which is able to cool the waveguide end to ambient temperature. The relationship between the sound velocity and temperature was worked out for the thickness measuring system and was used for correction of Ultrasonic Thickness Gauge readings. The deduced thicknesses are in good agreement with the actual values, which promises the feasibility of the method.