A steaming plant for the treatment of continuous webs of textile material which contain thermoplastic synthetic fibers, especially polyacrylic nitrile fibers of the like. The steaming plant includes a steaming chamber and a vat-shaped, bath-free cooling device which when viewing in the direction of movement of the web through the plant is located behind the steaming chamber. Air from the outside passes through the cooling device in a direction opposite to the direction of movement of the web, while between the steaming chamber and the cooling device there is arranged an air or steam floodgate or charging valve lock or seal (also identifiable as air-lock or steam lock as well as air-trap or steam trap) from which conduit means lead to a chimney or flue and/or to a blower.