Patent ID: 8573598

Claim:
A wall box assembly for a sootblower of the type having a lance tube for cleaning internal surfaces of a combustion device, and wherein a fluid cleaning medium flows through the lance tube during a cleaning cycle and is ejected from the lance tube within the combustion device, the lance tube passing through the wall box assembly and being retractable into and withdrawn from the combustion device, the wall box assembly comprising: a clamping seal assembly having a plurality of movable seal assemblies, the movable seal assemblies each having a seal element movable in a radial direction relative to the lance tube, the seal elements engageable with the outside surface of the lance tube in a sealing position and withdrawn from sealing contact with the outside surface of the lance tube in a released position, the seal elements movable between the sealing and released positions through the action of an actuator, wherein the clamping seal assembly includes a housing forming an internal chamber with a cylindrical wall and a circular jaw plate, the jaw plate mounted within the internal chamber with a clearance gap between the jaw plate and the cylindrical wall, the actuator being formed of a plurality of pistons retained by the jaw plate and each piston coupled with one of the seal elements and configured to move the one of the seal elements radially with respect to the jaw plate, and the jaw plate being radially movable within the internal chamber and self-centering around the lance tube.