What is DRA?
Drag Reducing Agents are long-chained polymers with a very high molecular weight. They commercially utilized to significantly reduce frictional pressure drop under turbulent flow conditions by injecting a very small amount (ppm) into the flowing fluid.
How does DRA work?
When DRA is injected into turbulent pipe flow, the active polymer ingredient dissolves in the fluid and elongates to form long “strings” which orientate themselves in the direction of flow then long chain polymer coils interact with and reduce turbulent energy in the fluid. It is believed that these agents work by directly reducing turbulence or by absorbing and later returning to the flowing stream energy that otherwise would have been wasted in turbulence cross flow.
Application of DRA
DRA is frequently used in the oil industry to reduce frictional pressure drop in the pipelines, which may result in the following applications:Decrease in discharge pressure when flowing into severely corroded pipelines, or to lowering the working pressure of the pump to extend the life of the pump and save energy.
Increase in terminus pressure of one section of pipeline in order to allow taking the next pump station offline for turbine maintenance purposes.
Increase in flow rate while discharge and terminus pressure remain constant, when higher flow rate is a concern.
Or a combination of the above mentioned cases.
Types of RapidFlow DRA
DRA for long crude oil pipeline [over 27 km] with flash point over 200 ºC, tailor-made for single phase and two phase crude oil.
Quick acting DRA for short pipelines [5 km to 27 km].
DRA with vegetable oil as suspending medium with flash point over 300 ºC [new composition formula].
DRA containing corrosion inhibitors for crude oil pipelines with high water cut.
Pump and System Curve
To reduce frictional pressure drop in hydro carrying pipelines, a cartain amount, as low as part per million, ppm by weight of high molecular polymers can be added to the liquid flowing through the pipeline to reduce the frictional energy losses and alter the relationship between pressure drop and flow rate. As it depicted in the figure, the system curve after RapidFlow DRA injection shows throughput increase at lower discharge pressure.
DRA as a unique solution for obstacles in pipelines
By DRA injection the pipeline will deliver the same flow to terminus while bypassing intermediate pump station when intermediate pump station is switched off for maintenance purposes. (Modified hydraulic pressure gradient under DRA injection shown in blue color).
In case that throughput increase is favorable and there is a need for standby pump to get back online, DRA can be injected in the pipeline, thereby increasing in throughput without bringing standby pump into operation.
Modeling & Optimization
Black Gold is able to manufacture the different type of injection pumps with different flow and pressure rating in accordance with customer requirements. Our injection pump skids are totally self-contained units which are delivered to siteand ready for operation once they are connected to the chemical shipping container and to a suitable electrical power supply. Performance and dependability of these pumps are of the highest standards.
The following illustrates an overview of injection RapidFlow DRA in pipelines.
Plunger (Piston) Driving Pumps
These Pumps can be produced in single head and double heads. These pumps include gauge for injection rate, calibration cylinder to calibrate the injection rate of pump.
|Discharge Pressure||0 – 110||Barge|
|Flow Rate||0.5 – 100||L/hr|