Case Study

CAROL successfully unloads mercury guard bed material

CAROL robot - remote catalyst removal

Our robotic catalyst removal technology successfully removed ceramics and carbon media, without the need for confined space entry during the unloading process.

The challenge

For its 2019 Gladstone LNG turnaround, an LNG operator asked EnerMech to help deliver and implement several technologies as they wanted to reduce the high-risk activities that are often involved with catalyst change outs. CAROL, the first commercial robot for catalyst unloading, was used to eliminate the need for workers to be inside the vessel.

The solution

CAROL was used to remove ceramic material from above the top tray in the vessel. The new rubber tips on CAROL’s screws provided grip on the tray’s smooth surface, allowing the robot to move throughout the entire vessel. Once the top tray was removed, CAROL was deployed in the main bed of one of the mercury guard bed reactors. CAROL removed most of the carbon media (30m3) in less time than a regular shift, with the robot working around three sample points that protrude towards the centre of the vessel.

CAROL was also trialed on a dryer where the adsorbent was fused together. It was hoped that CAROL's screws could break the agglomerated media in the bed, however, it was too severe for the screws to be effective.

CAROL catalyst unloading


CAROL demonstrated that catalyst removal technology can be used effectively to remove mercury guard material, reducing the need to put workers in high-risk situations during catalyst change outs. Confined space entry was limited to the top tray sections and a final clean at the bottom entry. What’s more, EnerMech replaced the internal top tray with a mesh screen to further reduce confined space entry for the next turnaround.

CAROL also proved its ability to operate in a wet environment when carbon beds are flooded with water to prevent a potential explosive atmosphere. Part of the CAROL unloading operations were live streamed to the client, so the turnaround team and other stakeholders could view the robot in real-time.

As we continue to develop our CAROL technology, Advisian Digital will apply the lessons learned from the fused dryer bed and look to develop additional tools to help CAROL break apart agglomerated media.

Aerial view of refinery