Membrane Water Wall

Boiler water walls are membrane walls that are made of tubes welded together with or without a strip of metal in between. These walls form the enclosure of the coal combustion chamber. Water wall tubes are also referred to as the evaporator section; they contain water mostly in liquid form which gradually evaporates as it rises in the boiler.

Challenges

As the water wall tubes form a lining along the whole boiler, they are submitted to a temperature gradient of 300 °C to 500 °C between the bottom section of the boiler and its top. To facilitate fitting, the panels in the boiler should preferably be made of steel grades that do not require any post-weld heat treatment. Vallourec supplies tubes for water walls in all grades, from carbon steel to advanced low-alloy steel, with outside diameters ranging from 31.8 mm to 63.5 mm.