ABSTRACT
The flow of liquid in a conduit, such as a pipeline, results in frictional energy losses. As a result of this energy loss, the pressure of the liquid in the conduit decreases along the conduit in the direction of the flow. For a conduit of fixed diameter, this pressure drop increases with increasing flow rate. The effect of a drag reducer added to a liquid is to reduce the frictional resistant in turbulent flow (Reynold’s number greater than about 2,100) compared with that of the pure liquid. Drag-reducing agents (DRAs) are sometimes known as friction reducers or flow improvers, although the latter term can be confused with wax inhibitors/pour-point depressants such as poly(meth) acrylic esters. DRAs interact with the turbulent flow processes and reduce frictional pressure losses such that the pressure drop for a given flow rate is less, or the flow rate for a given pressure drop is greater. In most petroleum pipelines, the liquid flows through the pipeline in a turbulent regime. Therefore, DRAs can perform very well in most pipelines. Because DRAs reduce frictional energy losses, increase in the flow capability of pipelines, hoses, and other conduits in which liquids flow can be achieved. DRAs can also decrease the cost of pumping fluids, the cost of equipment used to pump fluids, and provide for the use of a smaller pipe diameter for a given flow capacity. As crude oil is cooled to near its pour point, the effectiveness of DRAs may be reduced. The largest use of oil-soluble DRAs is for pipeline transportation of refined oils, not crude oils.
