Method and apparatus for extracting dust that is released when creping off a paper web

An apparatus for extracting dust entrained in a boundary layer of air adjacent an advancing paper web that is advanced along a predetermined path of travel comprising:

• a hood located adjacent one side of the predetermined path of travel of the web and having a width corresponding to that of the paper web and having a front side edge and a rear side edge with respect to the path of travel,
• an imperforate plane cover plate located adjacent the hood and defining an internal space between the cover plate and the hood, said cover plate being so positioned relative to said front side edge and said rear side edge of said hood as to form a gap along at least one of the front and rear side edges, and said cover plate being positioned in the predetermined path of travel of the web such that the web passes thereacross and the gap is situated in the dust containing boundary layer of air adjacent the advancing web, and
• means for producing a subatmospheric pressure in said internal space to draw air through said gap so as to effectively extract the boundary layer of air from the traveling web exclusively by suction while stabilizing the web as it travels along the path adjacent the imperforate plane cover plate.

A method of extracting dust entrained in a boundary layer of air running with an advancing paper web, wherein the dust is separated from the paper web as the paper web is creped off a Yankee dryer by a creping doctor, the method comprising the steps of

• directing the advancing web along a predetermined path of travel past a dust extractor having an internal space and an imperforate plate such that the predetermined path of travel of the web runs adjacent the imperforate plate, and wherein a rear edge, in relation to the direction of travel of the web, of said dust extractor has an adjustable transverse gap,
• extracting from the advancing paper web by suction into the internal space of the dust extractor at least a portion of the dust containing boundary layer by providing suction at such a volumetric flow rate that the air velocity in the gap is of the same order of magnitude as the velocity of the moving web and the air direction is opposed to the direction movement of the web and wherein the step of extracting dust includes adjusting the gap at said rear edge.

A method of extracting dust entrained in a boundary layer of air running with an advancing paper web, wherein the dust is separated from the paper web as the paper web is creped off a Yankee dryer by a creping doctor, the method comprising the steps of

• directing the advancing web along a predetermined path of travel past a dust extractor having an internal space and an imperforate plate such that the predetermined path of travel of the web runs adjacent the imperforate plate, and wherein the dust extractor has a front edge and a rear edge in relation to the direction of travel of the web, and
• extracting from the advancing paper web into the internal space of the dust extractor by suction at the front edge and at the rear edge of the dust extractor at least a portion of the dust containing boundary layer.

A method of extracting dust entrained in a boundary layer of air running with an advancing paper web, the method comprising the steps of

• directing the advancing web along a predetermined path of travel past a dust extractor having an internal space and an imperforate plane cover plate such that one side of the web runs adjacent the imperforate plate, and adjacent a gap along at least one of a front or rear edge, in relation to the direction of travel of the web, of said dust extractor, and
• extracting from the advancing paper web exclusively by suction into the internal space of the dust extractor at least a portion of the dust containing boundary layer.