TechNews: A robotic solution for a harsh environment

The recovery boiler smelt spout area is an unwelcoming and potentially dangerous place to work. However, essential regular tasks need to be carried out in the area for efficient and smooth operation of the boiler. A combined team of ANDRITZ design experts and workshop engineers have come up with a smart solution, the Smelt Spout Cleaning System, that enables essential work and maintenance to take place in a harsh environment.

Smelt can cause several issues in the spout area since it tends to coagulate and plug the openings, which means regular cleaning is essential. In most cases, this operation is carried out manually by the operators with long steel rods to remove solidified smelt. Splashing smelt and a hot environment may sometimes make the spout area a dangerous place to work.

Design and engineering teams from ANDRITZ in Finland merged and used their combined expertise to create a robotic solution that turns a possibly harmful task into an efficient, automated process. Jokke Jantunen, Product Engineer, Recovery Boilers, ANDRITZ says, “The smelt spout area has always been a potentially dangerous place to work due to the splashing smelt. The smelt spouts are sensitive to plugging and need to be cleaned regularly to prevent hot splashes and small explosions from occurring. In most recovery boilers, this task is carried out manually, which exposes personnel working in the spout area to possible injuries.”


“Our main mission is to provide our customers with the finest products that are also the safest to operate and maintain.”

Recovery and Power, Product Engineer, Recovery Boilers, ANDRITZ


After a lot of research and analyzing other products on the market – including other heavy industries where harsh environments are the norm – ANDRITZ teams collaborated and designed a solution that would fit the purpose by utilizing the latest in robotic technology. After a few trials and many experiments, they came up with the Smelt Spout Cleaning System, an automated, intelligent concept that will clean and maintain up to three ANDRITZ standard spaced smelt spouts using one robotic arm.

On the end of the arm is a specially designed tool that cleans away the solidified smelt.

© Riku Isohella


The robots are placed in front of the smelt spouts, hanging from a separate steel support construction. The robots are extremely powerful in order to deal with larger amounts of solidified smelt and one robot can clean up to three spouts using a long-reach arm. Despite its power, the robot recognizes the position of the spouts through positioning sensors and does not damage them during the cleaning procedure. On the end of the arm is a specially designed tool that cleans away the solidified smelt.

Safety elements have been paramount in the design of the Smelt Spout Cleaning System. The actual working area of the robots is isolated behind a safety fence and the area is locked and clear of personnel when in operation. Access to the area is by permission only, and when an operator wants to enter the area, robots are automatically driven into a standby mode.

The ANDRITZ Smelt Spout Robot at the testing environment in ANDRITZ Warkaus Works in Varkaus, Finland.

© Riku Isohella


The robots themselves are supplied by the German company KUKA Robotics, but it’s the bespoke design, tailor-made components, and actions for recovery boilers that have brought to life the Smelt Spout Cleaning System.

Jantunen says, “There has been a lot of knowledge, experience, and hard work applied to bringing the Smelt Spout Cleaning System to the market. We have implemented many features that are specifically designed for operation in the smelt spouts of recovery boilers, and we are really pleased with the results we are getting.”