Abstract: A shaft furnace bleeder valve for controlling a gas outflow from the interior of a pressurized furnace to the ambient atmosphere through an exhaust conduit is proposed. The bleeder valve comprises a valve seat associated with the exhaust conduit, a movable closure member having a central closure surface and a peripheral sealing surface cooperating with the valve seat, the closure surface comprising a convex surface at least in proximity to the sealing surface. The valve further has an actuating mechanism, which is connected to the closure member for moving the closure member between a closed position on the valve seat and an open position distant from the valve seat.

Abstract: A method for improving the operation safety of the smelt spout area of a recovery boiler, which smelt spout area comprises a working area (6), as well as smelt spouts (2) connected to the lower part of the boiler for directing the smelt from the boiler to a dissolving tank (4). In the method the smelt spouts (2) are separated from the working area (6) by a shielding wall (8, 10) arranged movable in relation to the smelt spouts. The invention also relates to a smelt spout area of a recovery boiler.

Abstract: A shaft furnace bleeder valve for controlling a gas outflow from the interior of a pressurized furnace to the ambient atmosphere through an exhaust conduit is proposed. The bleeder valve comprises a valve seat associated with the exhaust conduit, a movable closure member having a central closure surface and a peripheral sealing surface cooperating with the valve seat, the closure surface comprising a convex surface at least in proximity to the sealing surface. The valve further has an actuating mechanism, which is connected to the closure member for moving the closure member between a closed position on the valve seat and an open position distant from the valve seat.