Drag reduction in coal log pipelines

It is well-known that solutions of dissolved long-chain macromolecules produce lower friction or drag losses than with the solvent alone. In coal log pipeline (CLP), water is the conveying medium. Synthetic polymers such as poly(ethylene oxide) have been dissolved in water and tested for their extent of drag reduction as a function of concentration and other variables. Lab-scale experimental results for CLP indicate substantial drag reduction at low concentration levels of polymer. But, the macromolecules exhibit degradation under mechanical shear stresses. The large molecules break into smaller units. This degradation effect causes a loss of drag reduction. However, high levels of drag reduction can be maintained as follows: (1) by injecting polymer into the CLP at several locations along the pipeline, (2) by injecting polymer of different particle sizes, (3) by using more robust types of polymers, or (4) by using polymer-fiber mixtures. This report presents the value of drag-reducing agents in terms of pumping power net cost savings. In addition, this report outlines the environmental impact of drag reduction polymers, and end-of-pipeline water treatment processes. For an operating CLP, hundreds of miles in length, the use of poly(ethylene oxide) as a drag reducing agent provides significant pumping power costmore » savings at a minimal materials cost.« less