Container manufacturing plant comprising an air recycling circuit and recycling method

A method for recycling air in a plant (10) for manufacturing containers (12) from preforms (14), the plant including a protective enclosure (18) that isolates an interior volume (20) thereof from ambient air contained in an industrial premises (16), the protective enclosure (18) containing an oven (26) for thermally conditioning the preforms (14), said method comprising at least the following sequential steps:

• a) with an air-cooling device (34) comprised of i) ventilation means (32), located above the oven (26) and within the interior volume (20) of the protective enclosure (18), that draws in the ambient air contained in the industrial premises (16) through a wall of the protective enclosure (18), and ii) filtration means (36), located between the oven (26) and the wall of the protective enclosure (18), that filters the ambient air drawn from the industrial premises by the ventilation means (32) through the wall of the protective enclosure (18) to form filtered air exiting the filtration means (36) that is introduced into the oven (26) in order to cool at least part of the preforms (14) in transit inside the oven (26) using said filtered air introduced by the air cooling device (34), filtering, via the filtration means (36), the ambient air drawn in by the ventilation means (32) through the wall of the protective enclosure (18) and introducing said filtered air into the oven and onto the preforms to air-cool at least part of the preforms (14) while the preforms (14) are undergoing thermal conditioning in the oven (26);
• b) extracting the filtered air through ventilation means (32) and out from the oven (26) after said air has been used for cooling the preforms (14);
• and
• c) recycling at least some of said filtered air extracted from the oven (26) by piping said filtered air from an outlet of the ventilation means (32) and introducing all or some of said extracted air into an air inlet of one of the group consisting of a conversion unit (38) and a filling unit (48) of the plant (10).

A plant (10) for manufacturing containers (12) from preforms (14), comprising:

• a protective enclosure (18) with an interior volume (20) isolated from ambient air contained in an industrial premises (16) surrounding the protective enclosure (18);
• an oven (26) for thermally conditioning the preforms (14), the oven located within the interior volume (20) of the protective enclosure (18),
• the oven (26) comprising i) heating means (30) and ii) an air-cooling device (34),
• the air-cooling device (34) comprising i) ventilation means (32) that draws in the ambient air contained in the industrial premises (16) surrounding the protective enclosure (18), and ii) filtration means (36) that filters the ambient air drawn from the industrial premises by the ventilation means (32) to form filtered air, the air-cooling device (34) arranged with the ventilation means being located above the over (26) and with the filtration means being located between the oven (26) and a wall of the protective enclosure (18), the air-cooling device (34) for introducing the filtered air exiting the filtration means (36) into the oven (26) to blow on and cool at least part of the preforms (14) in transit inside the oven (26), and then to draw the air up the oven through the ventilation means for discharge out of the oven at a discharge side of the ventilation means (32);
• a conversion unit (38) for converting the preforms (14) into containers (12);
• a filling unit (48) for filling the containers (12) obtained from said preforms (14);
• and
• a cooling-air recycling circuit (60) comprising:
• i) extraction means (56) having an inlet side and an outlet side, the inlet side being connected to the outlet side of the ventilation means (32), the air discharged out of the oven through the ventilation means (32) being taken into the inlet side of the extraction means (56) to extract, from the oven (26), the filtered air introduced into the oven (26) by the air-cooling device (34), and
• ii) a first pipe (62) connected to the outlet side of the the extraction means and to an air inlet side of the conversion unit (38) and a second pipe (74) connected to the outlet side of the the extraction means and to an air inlet side of the filling unit (48) to convey said filtered air extracted from the oven (26) by the extraction means (56) into the air inlet side of the conversion unit (38) and the filling unit (48), such at least some of said air received through the wall of the protective enclosure, filtered by the filtration means (36), and then used for air-cooling the performs in the oven (26) is recycled at least directly into the air inlet of the conversion unit (38) and the filling unit (48),
• wherein the preforms (14) are thermoplastic preforms.