Convective system for a dryer installation

Abstract

The present invention concerns a convective system for a dryer installation for a passing web, more particularly paper. The convective systemis an assembly of an exterior casingfor suction of combustion products with openingtowards the web, with a firstand secondsuction ducts sucking the combustion products into the convective system. The combustion products coming from the first suction ductare guided through the exterior casingto a mixing and blowing device. Cold airis mixed in this mixing and blowing devicewith the combustion products, resulting in a gas mixture with lower temperature. The convective systemalso has an internal casinginside the external casing. This internal casinghas at least one opening towards the weband has also openingsallowing gas flow from the mixing deviceto the internal casingof said gas mixture. Under the internal casing, there is also a blowing duct. The second suction ductis also arranged under this internal casingthereby extracting a second flow of combustion productsinto the internal casing. This second flowof combustion products is then mixed with the gas mixturecoming from the mixing device, resulting in a mixture of gasseswith a temperature that is higher than the first gas mixtureand higher than e.g. 350° C. or 370° C., more preferably 390° C. or 410° C., even more preferably 420° C., 450° C. or 500° C. These hot gassesare then blown to the drying web by the blowing ductof the internal casing