GB1090877A - Method and apparatus for removing liquids from fibrous articles - Google Patents

Abstract

The liquid content of a wet fibrous article is reduced by pressing on to it a resilient body formed of polyamide particles and having a porosity of at least 15%, the pores being capillary in size and then removing from the polyamide body liquid transferred to it from the wet fibrous article. The article to be treated may be a web from a papermaking machine or a liquid-treated web. The polyamide body may be formed by sintering from particles of average diameter no more than 40 microns, and may be the surface of a roll, a platen or a die form. The liquid may be removed from it by applying vacuum to the same surface to which the wet article is applied, or to the other surface. Five embodiments are described. In the first (Figs. 1-3, not shown) paper from a wet press is passed through one or more presses each comprising a nonporous roll and a porous nylon roll. The latter comprises a number of porous rings mounted on a hollow, cylindrical, perforated roll mounted on a hollow perforated shaft. Vacuum is applied to the end of the shaft to withdraw liquid from the roll. In a second embodiment (Figs. 4 and 5, not shown), the press is like that of Fig. 1, but the roll comprises a continuous sleeve of porous nylon fitted on a metal shaft with circumferential grooves, communicating through longitudinal channels, and radial channels with a central channel to a vacuum source. In the third (Fig. 6, not shown) a sleeve of porous nylon is mounted on a solid shaft. A vacuum chamber is mounted to contact the surface of the roll after it has separated from the wet web, and so to remove liquid from it. In the fourth embodiment (Fig. 7, not shown), suitable for pressing flat paperboard, the wet board is placed between two flat sheets of porous polyamide. These are then placed between two perforated platens and pressed while vacuum is applied to the space above the upper platen. In the fifth embodiment (Figs. 8 and 9, not shown) four forming dies are rotatably mounted on retractable arms on a shaft. Vacuum or compressed air can be applied through each arm. Each die in turn is immersed in a tank of fibrous slurry, white vacuum is applied to form a fibrous mat. Each die is then rotated until it is opposite a complementary form in a wheel. This form comprises a shaped body of porous nylon on a perforated support plate with a vacuum chamber behind it. The fibrous web is transferred from the die to the complementary form, and when its liquid content has been sufficiently reduced is again transferred to a conveyor which takes it to a dryer.