(438b) Compact Rotating Packed Bed Contactor for Process Intensification in Offshore and Onshore Gas Separations

Mello, M. - Presenter, Chevron Energy Technology Company
Conventional tray or packed towers have been traditionally used for gas separations. The towers perform satisfactorily, but they have disadvantageous characteristics for sites where space and weight are at a premium such as offshore marine environments or onshore retrofits: footprint, height (need to be vertical, especially for tray towers), weight, foaming issues, large liquid inventory, relatively low turn-down ratio, high cost of installation and difficulty in modularization.

Rotating Packed Bed technology (also known as â??Higeeâ?) is one of the recognized Process Intensification technologies in industry. It can shrink the process unit size significantly as compared with conventional technologies. The RPB internals consist of a high surface area donut shaped rotating packed bed mounted on a shaft in a pressure vessel. Gas enters from the outer radius surface of the packed bed, flows radially inwards, and passes through the whole packing before exiting through the center eye. Liquid is sprayed through a series of nozzles in the center eye into the inner radius surface of the packing and flows radially outwards through the packing due to the centrifugal force. The liquid, moving counter-currently to the gas, exits at the outer surface of the packing. Internal seals are used to ensure that there is no gas or liquid bypass or short-circuiting around the packed bed.

The high centrifugal force generated by rotation in the RPB allows the formation of thin liquid films, small droplets and high liquid-gas interfacial areas in the packing leading to significantly higher mass transfer coefficient than conventional (tray or packed tower) technology. The significantly higher mass transfer coefficient of the RPB leads to reduced footprint, weight, height and CAPEX. In addition, RPB offers other benefits such as high turn-down ratio, low liquid hold-up, elimination of anti-foaming agent.

The use of RPB as an alternative compact technology for gas processing will help to monetize Chevronâ??s equity gas both onshore and offshore through the use of reduced size and weight equipment.

This talk will review the latest developments in the technology and will discuss the efforts within Chevron to develop the technology for the gas processing application.