De-asphalting
With the increasing use of heavy crude oil as a feedstock, refineries are modifying their facilities to include a De-asphalting system. The system, which is located downstream of the vacuum distillation tower, uses a pump to cycle the vacuum tower bottoms residuum through an additional treatment process to further harvest valuable distillates from the residue. A solvent like propane, pentane or butane is mixed with the charge stock prior to its entry into a vertical separation vessel to dissolve the molecular bonds of the inputted fluid, thereby increasing the yield of de-asphalted oil and asphaltenes. By means of a multistage separation and stripping process, the de-asphalted oil is further treated, to condition it for its ultimate use as feedstock for a fluid catalytic cracker or hydrocracker. The separated asphaltenes are reheated prior to injecting into a stripping vessel, with the final product being pumped to asphalt handling facilities for distribution to road asphalt plants or roof shingle manufacturers.
De-asphalting services, similar to those residuum fluid-handling applications found on upstream distillation systems (atmospheric and vacuum types), need to manage highly viscous products due to the concentrated asphaltene content. This sticky process fluid, which is often laden with a high concentration of solid contaminants, demands a robust and efficient pumping technology. In these services proper heat tracing and insulation of the pumps, and in particular their shaft seal(s), is essential to achieve good pump life. Operating the pumps at reduced speeds will also help to extend the design life of the pump rotating assembly and mechanical seals, while also affording the best suction lift capabilities.
Have you considered the value of using rotary PD pumping technology?
Refinery production managers and operators around the globe have experienced the benefits that volumetric, rotary PD pumps can bring to these services. Having one machine that can efficiently transport heavy, medium and lightweight products simplifies the number of pieces of fluid-handling equipment required at these facilities. Controlling the rotary PD pumps with an adjustable speed drive allows operations to be performed in a "timed" manner without the need for flow control valves, eliminating the need for the recirculation of surplus process fluid. This reliable system control method takes full advantage of the tremendous turndown flow range of rotary PD pumps and their inherent high suction lift capability, making them an ideal fluid-conveying solution for your De-asphalting systems.