Steam drying device for paper making machine

Claim 2

In a papermaking machine having travelling web-supporting means, headbox means for depositing stock onto said websupporting means, and suction means for removing water from the stock downstream of said headbox means to form a progressively dewatered paper web, the improvement which comprises: means positioned opposite said suction means for applying a high mass rate flow blanket of steam substantially at atmospheric pressure to said web substantially uniformly throughout a planview area extending across said web and an area sufficient to dewater the web by evaporation without damaging the web by steam impingement thereagainst, said means for applying a high mass rate flow blanket of steam comprising a housing having a substantially uniform transverse dimension substantially to encompass the width of said web and presenting an unrestricted discharged throat of sufficient plan view area to deliver steam at said high mass flow rate without damaging said web, a final steam delivery chamber having openings facing away from said throat, and delivering steam into said housing, at least one further steam delivery chamber within said final delivery chamber having openings facing toward said throat, said openings in said final delivery chamber and said further chamber being sized to reduce the pressure of said steam in stages to provide substantially atmospheric pressure steam at a sufficient mass flow rate to dewater said web by evaporation.

Claim 3

In a papermaking machine as defined in claim 1 wherein said housing means includes an arched roof facing said throat, said final delivery chamber is in the form of a cylinder extending along the length of and spaced closely to said roof, and said further chamber is in the form of a cylinder and substantially coextensive in length with said cylinder.

Claim 4

In a papermaking machine as defined in claim 2 wherein said further chamber is eccentrically disposed within said final chamber in the direction of said throat.

Claim 5

In a paper making machine as defined in claim 1 and further characterized in that the openings in the further steam delivery chamber are of a constant size and of a spacing which progreSsively diminishes away from said means for supplying steam.

Claim 6

In a paper making machine as defined in claim 1 further characterized in that the openings in the further steam delivery chamber are of equidistant spacing and which progressively increase in a size from said means for supplying steam.

Claim 7

In a paper making machine including travelling web-supporting means having a partially dewatered paper web thereon, and drying means for receiving said web, the combination of: supply means for supplying steam at a pressure sufficiently high to deliver steam to said web, prior to introduction to said drying means, at a flow rate high enough to evaporate water from said web; and steam applicator means disposed adjacent said web-supporting means and connected to said supply means for reducing the pressure of said steam in stages substantially to atmospheric pressure and applying it at said high mass rate of flow to said web whereby to remove water from the web by evaporation, said steam applicator means comprising a housing having a substantially uniform transverse dimension substantially to encompass the width of said web and presenting an unrestricted discharge throat of sufficient plan veiw area to deliver steam at said high mass flow rate without damaging said web, a final steam delivery chamber having openings facing away from said throat and delivering steam into said housing, at least one further steam delivery chamber within sid final delivery chamber having openings facing toward said throat, said openings in said final delivery chamber and said further chamber being sized to reduce the pressure of said steam in stages to provide substantially atmospheric pressure steam at a sufficient mass flow rate to dewater said web by evaporation.

Claim 8

In a paper making machine including travelling web-supporting means having a partially dewatered paper web thereon, and drying means for receiving said web, the combination of: supply means for supplying steam at a pressure sufficiently high to deliver steam to said web, prior to introduction to said drying means, at a flow rate high enough to evaporate water from said web; and steam applicator means disposed adjacent said web-supporting means and connected to said supply means for reducing the pressure of said steam in stages substantially to atmospheric pressure and applying it at said high mass rate of flow to said web whereby to remove water from the web by evaporation, said steam applicator means comprising a housing having a substantially uniform transverse dimension substantially to encompass the width of said web and presenting an unrestricted discharge throat of sufficient plan veiw area to deliver steam at said high mass flow rate without damaging said web, a final steam delivery chamber having openings facing away from said throat and delivering steam into said housing, at least one further steam delivery chamber within sid final delivery chamber having openings facing toward said throat, said openings in said final delivery chamber and said further chamber being sized to reduce the pressure of said steam in stages to provide substantially atmospheric pressure steam at a sufficient mass flow rate to dewater said web by evaporation.