Method of dewatering wet web using an integrally sealed air press

A method for making a cellulosic web comprising the steps of:

• a) depositing an aqueous suspension of papermaking fibers onto an endless forming fabric to form a wet web;
• b) dewatering said wet web to a consistency of from between about 10 percent to about 30 percent;
• c) further dewatering said wet web to a consistency of from between about 30 to about 40 percent using an air press that is adapted to cause at least about 85 percent of a pressurized fluid at at least 15 pounds per square inch gauge to flow through said wet web due to an integral seal formed between an air plenum and a collection device;
• d) transferring said wet web to a molding fabric to give said wet web a molded structure and a bulk of at least about 8 cubic centimeters per gram;
• e) pressing said dewatered and molded web against a surface of a heated drying cylinder with said molding fabric to preserve said molded structure and said bulk of at least about 8 cubic centimeters per gram;
• and
• f) drying said web to a final dryness.

A method for making a cellulosic web comprising the steps of:

• a) depositing an aqueous suspension of papermaking fibers onto an endless forming fabric to form a wet web;
• b) sandwiching said wet web between a pair of fabrics to form a wet web structure, at least one of said fabrics being a three-dimensional molding fabric;
• c) passing said wet web structure between an air plenum and a collection device with said three-dimensional molding fabric disposed between said wet web and said collection device, said air plenum and said collection device being operatively associated and adapted to create a pressure differential across said wet web structure of at least about 30 inches of mercury and direct a stream of pressurized fluid through said wet web structure of at least about 10 standard cubic feet per minute per square inch;
• d) dewatering said wet web using said stream of pressurized fluid to a consistency of at least about 30 percent;
• e) pressing said dewatered web against a surface of a heated drying cylinder with a fabric;
• and
• f) drying said web to a final dryness.

A method for making a cellulosic web comprising the steps of:

• a) depositing an aqueous suspension of papermaking fibers onto an endless forming fabric to form a wet web;
• b) covering said wet web with a support fabric to form a wet web structure;
• c) transporting said wet web structure through an air press, said air press including an air plenum and a collection device which are operatively associated with each other and adapted to create a pressure differential across said wet web structure, said air plenum and said collection device cooperating with said wet web structure to form an integral seal therewith;
• d) passing a stream of pressurized fluid of at least about 5 psig and having a volume of at least about 10 standard cubic feet per minute per square inch through said wet web structure from said air plenum to said collection device and creating a vacuum in said collection device of at least about 10 inches of mercury to cause a pressure differential across said wet web structure of at least about 25 inches of mercury, said pressure differential noncompressively dewatering said wet web to a consistency of at least about 25 percent;
• e) transferring said dewatered web to a third fabric;
• and
• f) pressing said dewatered web against at least a portion of a heated drying cylinder using said third fabric to a obtain a desired final dryness.

A method for making a cellulosic web comprising the steps of:

• a) depositing an aqueous suspension of papermaking fibers onto an endless forming fabric to form a wet web;
• b) covering said wet web with a support fabric to form a wet web structure;
• c) transporting said wet web structure through an air press, said air press including an air plenum and a collection device which are operatively associated with each other and adapted to create a pressure differential across said wet web structure, said air plenum and said collection device cooperating with said wet web structure to form an integral seal therewith;
• d) passing a stream of pressurized fluid of at greater than 10 psig through said wet web structure from said air plenum to said collection device and creating a vacuum in said collection device of at least about 10 inches of mercury to cause a pressure differential across said wet web structure of at least about 25 inches of mercury, said stream of fluid having a volume of at least 10 standard cubic feet per minute per square inch, said pressure differential noncompressively dewatering said wet web to a consistency of at least about 25 percent;
• e) transferring said dewatered web to a third fabric;
• and
• f) pressing said dewatered web against at least a portion of a heated drying cylinder using said third fabric to a obtain a desired final dryness.