A method for drying drying-stock includes separating solvent-containing drying stock within a drying unit into a base material and a solvent with the aid of a first heat transfer medium that flows through a first circuit, where after the solvent has been taken up by the first heat transfer medium, the solvent is extracted from the heat transfer medium via heat energy (condensation), where the heat energy is transferred by a heat exchanger with the aid of an evaporation unit to a second circuit and made available to a second heat transfer medium, and where the heat energy is fed in a condensation unit of the heat pump back to the first circuit with the aid of a heat pump.

A method for operating a heating group subsystem of a machine for the production or treatment of a fibrous web. The heating group subsystem includes a first heating group and a last heating group and at least one additional heating group; in each case having at least one device that is heated with pressurized heating steam. Viewed in a direction of travel, the fibrous web is fed first through the first heating group, then through the at least one additional heating group, and thereafter through last heating group. The steam pressure of the heating steam of the at least one additional heating group is adjusted lower than the respective steam pressure of the heating steam of first heating group and of last heating group.

A method for operating a heating group subsystem of a machine for the production or treatment of a fibrous web. The heating group subsystem includes a first heating group and a last heating group and at least one additional heating group; in each case having at least one device that is heated with pressurized heating steam. Viewed in a direction of travel, the fibrous web is fed first through the first heating group, then through the at least one additional heating group, and thereafter through last heating group. The steam pressure of the heating steam of the at least one additional heating group is adjusted lower than the respective steam pressure of the heating steam of first heating group and of last heating group.

An exemplary process air recirculation system, and an electric heater mixing apparatus is disclosed herein. Exemplary process air recirculation systems comprise the electric heating mixing apparatus. An exemplary electric heating mixing apparatus comprises: walls defining a first chamber having a first upstream opening and a first downstream opening, and a second chamber having a first upstream opening and a first downstream opening, wherein the second chamber is adjacently disposed to the first chamber, a first inlet damper disposed at the first upstream opening, a second inlet damper disposed at the second upstream opening, and a resistance-type electric air heater disposed in the first chamber.

A papermaking process including the steps of forming a wet paper web on a papermaking machine, pulling vacuum through the web to remove water from the web and thereby generate discharge air, and diverting at least a portion of the discharge air through a control loop to a hot air drying system within the papermaking process to aid in drying the web, wherein the vacuum is generated by centrifugal blowers.

A papermaking process including the steps of forming a wet paper web on a papermaking machine, pulling vacuum through the web to remove water from the web and thereby generate discharge air, and diverting at least a portion of the discharge air through a control loop to a hot air drying system within the papermaking process to aid in drying the web, wherein the vacuum is generated by centrifugal blowers.

A method for operating a heating group subsystem of a machine for the production or treatment of a fibrous web. The heating group subsystem includes a first heating group and a last heating group and at least one additional heating group; in each case having at least one device that is heated with pressurized heating steam. Viewed in a direction of travel, the fibrous web is fed first through the first heating group, then through the at least one additional heating group, and thereafter through last heating group. The steam pressure of the heating steam of the at least one additional heating group is adjusted lower than the respective steam pressure of the heating steam of first heating group and of last heating group.

A method for operating a heating group subsystem of a machine for the production or treatment of a fibrous web. The heating group subsystem includes a first heating group and a last heating group and at least one additional heating group; in each case having at least one device that is heated with pressurized heating steam. Viewed in a direction of travel, the fibrous web is fed first through the first heating group, then through the at least one additional heating group, and thereafter through last heating group. The steam pressure of the heating steam of the at least one additional heating group is adjusted lower than the respective steam pressure of the heating steam of first heating group and of last heating group.

An installation for drying a web of non-woven material includes a fan (6), a heating oven (3), an outlet pipe (C2) which puts the outlet of the oven (3) in communication with the intake of the fan (6), a branch pipe (C3) branching from the inlet pipe (C1) upstream of the heat source (4) putting the pipe (C1) in communication with the inlet of a drying device (10, 11), a pipe (C4) for the extraction of air from the drying device (10, 11) and a humidity level probe (13) mounted in the extraction pipe (C4).

An installation for drying a web of non-woven material includes a fan (6), a heating oven (3), an outlet pipe (C2) which puts the outlet of the oven (3) in communication with the intake of the fan (6), a branch pipe (C3) branching from the inlet pipe (C1) upstream of the heat source (4) putting the pipe (C1) in communication with the inlet of a drying device (10, 11), a pipe (C4) for the extraction of air from the drying device (10, 11) and a humidity level probe (13) mounted in the extraction pipe (C4).