Leonard launches dual-head robot for refractory demolition

Dual head robot arm (Image: Leonard)

The Descender Duo has been designed to demolish castable refractory, cut and weld anchors, and spray-on refractory inside boilers, calciners and silos in the cement, metals, waste-to-energy and petrochemical sectors.

Weighing less than two tonnes, the robot arm comes pre-assembled. It requires an opening of 1.2 metres squared for access before being lowered into the vessel from where it can be operated by remote control using on-board live feed cameras.

Once in position, with the support of an external overhead hoist, the non-loadbearing stabilising legs are extended using electric hydraulics to secure the robot.

The dual headed configuration offers 360-degree rotation, ideal for working in vessels of approximately 9 metres (29.5ft) in diameter, says Leonard, but it can be extended with strategic porthole placements.

Compared to manual operation, the electric-powered robot arm delivers higher productivity with up to 50%-time savings, according to the manufacturer.

Because it can operate at temperatures of 100°C+ (212 °F+), work can also begin faster – from as little as 24 hours after burner off.

With two heads working simultaneously, the robot provides double the operational capacity. It is controlled by two remotes, meaning the heads can carry out either the same, or different, tasks, for example cutting anchors on one arm while performing demolition and spraying refractory on the other.

Development phase and debut

The Descender Duo recently debuted at Burmeister & Wain Scandinavian Contractor’s (BWSC)’s Lisahally power station in Derry Londonderry, Northern Ireland.

Beforehand, the Danish power plant specialist and Leonard had worked together for several years to explore safer ways of supporting shutdown activity across the facility; however, the 26-metre furnace presented an access challenge. Extensive pipework surrounding the exterior meant a fully customised solution was necessary.

Commenting on this challenge, which led to the development of the Descender Duo, managing director Mark Leonard said, “We took our years of cement plant experience, coupled with our working knowledge of the BWSC plant, and designed, engineered and tested a completely new vertical solution within just seven weeks from that initial conversation with the customer.”

Traditionally, the furnace was shut down and allowed to cool for up to a day and a half before preparatory works would commence to allow a team on rope access to enter the hazardous space and remove slag manually.

With the Descender Duo work can begin 24 hours after the furnace is powered down, saving up to a one day of downtime. The process helped keep at least six people out of the high-risk interior of the vessel and returned 26 hours to the shutdown programme, the company reports.

“The effectiveness exceeded expectation,” plant manager Martin Doran said.

“When the Descender Duo concept was first discussed, we had to spend some time with the team from Leonard looking at how it was going to be moved into the furnace.

“Every site is different and that presented its own challenges, but nothing that the team couldn’t overcome. Once it was installed, we were hugely impressed by its efficiency.”