In this video, we’ve removed the top cover from the carriage, to show you where the progressive helix mechanism (PHM) fits inside the IK-700 retractable sootblower. This sootblower has a four-inch helix, meaning for every revolution, the lance tube travels four inches. While four-inches is the standard, some sooblowers have a six- or eight-inch helix.

A PHM model provides a closer look at the gear rack, which is driven by the pinions in the carriage, and a friction key, which provides extra resistance and keeps the component in place. As the pinion rotates, torque is applied to push the PHM rear sliding rack back, creating a one tooth wide opening. When the PHM snaps shut, the pinion will move one tooth over and the nozzles will then cover a different cleaning path on the way in and out.

It takes roughly 414 cycles before the nozzles cover the same cleaning path, providing for more thorough cleaning and helping to prevent erosion inside the boiler. The PHM allows the lance tube to come to rest at a different orientation each time, removing any permanent heat set which could cause the lance tube to droop.

Progressive helix mechanisms are made for all B&W Diamond Power^® retractable sootblowers and can be retrofitted onto existing equipment.