Inspectors in Mörrum (Sweden) needed to conduct a scheduled inspection of a recovery boiler and decided to use the unmanned aerial vehicle (UAV) Elios for the inspection.

The boiler is a giant cuboid that stands 60 meters high. The walls are built up by pipes filled with circulating water, resulting in a cooled construction. Black liquor is fed into the furnace through nozzles and burnt at high temperature.

Shutting the boiler down for an inspection costs about 1 000 000  dollars a day, so every single minute that can be saved for the outage is crucial.

Building a scaffold that allows inspectors access to every part of the boiler is challenging, since there are so many small elements on the top and bottom, and so many tight spaces to navigate. Given all of these complexities building the scaffold can take two-three days, time in which the boiler has to be shut down. The scaffold is also expensive - it costs about $20 000 to build it for each individual inspection.

Benefits of inspection by use UAV Elios 2:

SAFETY

Elios allowed inspectors to closely view burners, tubes and openings that are usually difficult to access using manual methods. During the inspection no person came inside the boiler.

COST REDUCTION

The inspection lasted only one day and allowed us to work and profit for the next two days. Some cost was saved by not having to build a scaffold.

EFFICIENCY

With the help of the UAV only for a few hours of inspection were collected all the necessary visual data of hard-to-reach inspection sites.