The Descender Duo has been designed to demolish tough castable refractory, cut and weld anchors, and spray on refractory inside boilers, calciners and silos in the most demanding industries: cement, metals, waste-to-energy, and petrochemical.
Like the name suggests, the Descender Duo is lowered into vessels and operated via remote control using its on-board live feed camera, giving operators full visibility while completely removing people from confined, hazardous spaces. By reducing the need for personnel to enter vessels, it also helps shorten the critical path of shutdowns.
Relatively light at less than two tonnes, the Descender Duo is pre-assembled for immediate deployment and, in line with Leonard’s wider suite of robotic arm solutions, requires only a compact 1.2 m2 opening to access vessels. Once in position, with the support of an external overhead hoist, the non-loadbearing stabilising legs are extended using electric hydraulics to secure the Descender Duo as it descends through the vessel.
The dual headed solution offers full 360-degree rotation and is ideal for working in vessels of approximately 9m (29.5ft) diameter, however that can be extended with strategic porthole placements. The Descender Duo delivers high productivity with up to 50% time savings compared to manual methods. Its ability to operate at temperatures of 100°C+ (212°F+) also enables work to begin faster – from as little as 24 hours after burner off – while its all-electric power supply provides a reliable, cost-effective, and cleaner energy source.
The Descender Duo provides double the operational capacity with two robotic heads working simultaneously. Operated using two remote controllers, it gives operators the flexibility to perform the same, or different, tasks simultaneously, from cutting anchors on one arm to demolition and spraying refractory on the other.
The Descender Duo recently debuted at Burmeister & Wain Scandinavian Contractor’s (BWSC)'s Lisahally Power Station in Derry~Londonderry, Northern Ireland, a critical piece of infrastructure that generates electricity from grade C waste wood for some 40 000 homes and businesses.
The Danish headquartered power plant specialist and Leonard had already worked together for several years to explore safer ways of supporting shutdown activity across the facility, however the 26-metre furnace presented a very different access challenge. Extensive pipework surrounding the exterior meant a fully customised solution was necessary.
Mark Leonard, managing director at Leonard said: “It required new thinking and rather than step away from the problem we were committed to solving it for the customer, with the customer. We’re relentless in our approach to tackling complex challenges, head-on. 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. That solution was the Descender Duo as we know it today.”
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 began just 24 hours after the furnace was powered down, saving up to a one day of downtime. The entire process help keep at least six people out of the high-risk interior of the vessel and returned 26 hours to the shutdown programme.
“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.”
