Abstract: A tower for cooling a liquid includes an impermeable outer wall, and a flexible but non-stretchable, porous, air-permeable inner wall spaced inwardly from the outer wall to define a chamber between the two walls. The air-permeable inner wall has a multiplicity of pores through which air can pass in order to remove deposits from the internal face of the inner wall. A delivery means is provided for injecting air into the chamber between the two walls, and further delivery means injects air into the internal volume within the inner wall, this being the cooling air. A further means sprays the liquid into the internal volume surrounded by the inner wall.

Abstract: A cover is provided for a launder, or an equivalent open-topped vessel for containing molten metal, the cover including a heat-insulative layer spanning the open top of the vessel, with a spacer arrangement to maintain a gap of uniform width between the heat-insulative layer and the open-top. A housing defines an evacuation plenum, and connections are made to allow an exhaust device to remove gaseous materials from the plenum. Adjacent the gap is an air-guide arrangement which directs outside air into the evacuation chamber along a path which is intercepted by any gaseous materials exiting through the gap, whereby such gaseous materials are entrained into the evacuation chamber.