The disclosure is directed towards a through-air drying system comprising a hood and a rotatable cylinder with a porous cylindrical deck. The system includes a seal, and more particularly a seal along the lateral edges of the system. The seal generally prevents the exhaust of drying medium from the system through the gap between the hood and the rotatable cylinder and enables the system to be operated at positive air pressure. The seal may be formed by providing the hood with an axial hood flange, which extends at least partially along the bottom edge of the hood and overlaps an axial annular flange disposed on the cylinder when the hood is in a closed and sealed position.

The disclosure is directed towards a through-air drying system comprising a hood and a rotatable cylinder with a porous cylindrical deck. The system includes a seal, and more particularly a seal along the lateral edges of the system. The seal generally prevents the exhaust of drying medium from the system through the gap between the hood and the rotatable cylinder and enables the system to be operated at positive air pressure. The seal may be formed by providing the hood with an axial hood flange, which extends at least partially along the bottom edge of the hood and overlaps an axial annular flange disposed on the cylinder when the hood is in a closed and sealed position.

Disclosed is a through-air dryer shower assembly disposed within the through-air dryer and enables efficient cleaning of the through-air dryer without having an operator enter the dyer. The shower may comprise an elongated shower conduit having a plurality of nozzles disposed thereon and may be affixed to a baffle disposed within the through-air dryer cylinder. The shower assembly is generally positioned to spray a pressurized stream of wash fluid against the interior surface of the dryer causing debris accumulated within the deck to flow through the structure to the outer surface for discharge.

An apparatus for measuring flowing suspension includes a radiation source that directs wave motion to the suspension, a flow causing particles of the suspension to be sorted by size. A measuring arrangement measures first values of a first parameter of the wave motion interacted with the suspension at a first wavelength band of the wave motion, and measures second values of at least one of the following: a second parameter of the wave motion interacted with the suspension, and the first parameter of the wave motion interacted with the suspension at a second wavelength band of the motion, the measurement of the first and second values being synchronized. The arrangement forms at least one comparison being configured to relate to one of the first and one of the second values, and forms a distribution with at least one of first values as a function of one of the comparisons.

When the efficiency of heating with steam is enhanced by adding a condensed water film formation-suppressing amine in a heating step of heating a material to be heated with the steam via a metallic material, the amount of the condensed water film formation-suppressing amine to be added is controlled based on any of the concentration of the condensed water film formation-suppressing amine in a drain, the pH of the drain, the electroconductivity of the drain, the amount of the drain, the amount of the steam, the temperature of the drain, the temperature of the metallic material, and the amount of the metallic material eluted in the drain.

Provided are tissue webs and products that have a modest degree of surface texture, but are still soft. In certain instances the tissue products and webs may also have good sheet bulk and low stiffness. For example, the tissue products may have good softness, such as a TS7 value (measured using the EMTEC Tissue Softness Analyzer) less than 11.0, and a textured surface, such as an R2 value from about 11,000 to about 20,000 (measured using an OpTiSurf tester). The foregoing tissue products may have a sheet bulk greater than about 8.0 cc/g and a Stiffness Index less than about 15.0. In certain instances the tissue product and webs may be through-air dried and may be either creped or uncreped.

Methods of improving the drying rate of a cellulosic web, such as a tissue web, by providing an apparatus having two noncompressive dewatering devices, such as two through-air driers, where the temperature of the drying medium supplied to each device is separately controlled. The temperature of the medium supplied to the first device may exceed 450 F., such as from about 450 to about 600 F. On the other hand the temperature of the medium supplied to the second device may be less than the temperature supplied to the first, such as from about 350 to 450 F. Drying the web in this manner not only improves drying efficiency, but also limits or prevents degradation of the web, such as the combustion of cellulosic fibers making up the web or monosaccharides associated therewith. As such, webs that are substantially free from furan and acetaldehyde may be produced by the present methods.

Systems and methods for drying or bonding materials are described. A material to be dried or bonded may be passed through a through air dryer (TAD) or through air bonder (TAB). Some of the air output by the TAD/TAB may be recirculated to be passed back through material. As the air is recirculated, it is heated and mixed to a desired uniform temperature distribution. As heated air of the desired uniform temperature distribution is passed through ducting for transport to the material, the desired uniform temperature distribution deteriorates due to heat loss experienced at the walls of the ducting. Heating tape is implemented with respect to particular locations of ducting and selectively operated to maintain air traveling through the ducting at the desired uniform temperature distribution. Heat generated by the heating tape is used to counteract heat loss experienced by air traveling through the ducting.

Methods of improving the drying rate of a cellulosic web, such as a tissue web, by providing an apparatus having two noncompressive dewatering devices, such as two through-air driers, where the temperature of the drying medium supplied to each device is separately controlled. The temperature of the medium supplied to the first device may exceed 450 F., such as from about 450 to about 600 F. On the other hand the temperature of the medium supplied to the second device may be less than the temperature supplied to the first, such as from about 350 to 450 F. Drying the web in this manner not only improves drying efficiency, but also limits or prevents degradation of the web, such as the combustion of cellulosic fibers making up the web or monosaccharides associated therewith. As such, webs that are substantially free from furan and acetaldehyde may be produced by the present methods.

Described herein are devices and methods for the drying of permeable and semi-permeable webs such as paper products in a physical environment with limited space while providing for higher flow rates. The devices and methods of the present invention are for use with rotating, foraminous shelled roll dryers and are implemented by redesigning the aspects of the devices and methods associated with exhausting spent drying gas.