Patent GB-809694-A (GB)
Title: Humidifier with control system for humidifying articles or travelling webs of paper or regenerated cellulose
IPC: B29D7/00
Filed: 1956-07-12
Abstract: <PICT:0809694/IV (a)/1> <PICT:0809694/IV (a)/2> <PICT:0809694/IV (a)/3> <PICT:0809694/IV (a)/4> <PICT:0809694/IV (a)/5> A humidifier for moistening hydrophilic materials, especially for humidifying running webs of hydrophilic sheet material such as regenerated cellulose film and paper, comprises a vertical or horizontal chamber, means for passing the hydrophilic materials through the chamber, and means for subjecting the materials to saturated steam in the chamber, and is characterized by means for reducing or cutting off the supply of steam to the chamber, to prevent over-humidification, when the passage of the materials through the chamber temporarily ceases.  As shown in Fig. 1, a multi-colour printing press P is provided with conventional printing and drying rolls 10, 11.  The web S, which may be regenerated cellulose film or a sheet of paper or glassine, passes from the press and is carried over a guide roll 12 into the humidifier chamber 13.  The web then travels downwardly through the latter and around a cooling roll 14.  Saturated steam is admitted to two banks of steam coils 25, 26 (Fig. 2) in the chamber on either side of the travelling web through steam line 32 (Fig. 1), valve 39 and vertical headers 27, 28 provided with pressure gauges 29.  The horizontal steam lines or runners 30 connecting the headers are provided with jets 31 (Fig. 3) through which steam is discharged directly on to the web, or with jets 31A through which steam is discharged indirectly on to the web (Fig. 2).  The jets 31 have an angled bore 38 which has a horizontal outlet portion which directs the steam generally at right angles against the web.  If the web is composed of very absorbent material such as glassine, jets 31a are used to direct the steam upwardly at an angle of about 45 degrees against the lateral slats 35 of baffle assemblies 36 which are supported from the uppermost horizontal runner 30 by adjustable hangers 37 (Figs. 2 and 4). The horizontal runners 30 are bent slightly downward at each end to prevent accumulation of condensate, and the baffle slats 35 are similarly shaped so that they are in alignment with the jets 31a (Fig. 4).  When direct impingement of the steam normal to the web is desired and the jets 31a are used, the baffle sections 36 are raised or removed from in front of the banks 25, 26 so that the lateral slats 35 are no longer interposed between the jets 31a and the web.  Air and excess steam are withdrawn from the chamber through ducts 15, 16, and the elongated intake sections 19, 20 of the ducts are surrounded by the uppermost row of banks of steam coils 17, 18, to which saturated steam is supplied through pipes 21, 22 respectively.  Condensate or saturated steam is exhausted from the coils through pipes 23, 24.  The main switch 40 (Fig. 5) for starting the printing press motor 41 also controls the opening and closing of valve 39 through an electro-pneumatic relay 42 connected to air line 43 through a combined pressure regulator and air filter 44.  The discharge air line 45 from relay 42 is connected to the pneumatic coil valve 39 so that, when switch 40 is closed, the valve 39 will eventually open to admit steam into the upper header lines 46, 47.  There is a delay of several seconds between the time when switch 40 is closed and the actual entry of steam into lines 46, 47, so that discharge of steam on to the web in the humidifier during the short temporary closing of switch 40, for the purpose of registering the web on the printing rolls, is avoided.  The positioning of the jets 31, 31a above the centres of the horizontal runners 30 is an additional means of preventing premature discharge of the steam from the jets. Condensate in the banks 25, 26 is removed through four large exhaust lines 48-51.  When the materials to be humidified are in the form of separate articles, such as sheets, the humidifier is provided with a substantially horizontal porous endless belt upon which the articles are supported during their passage through the chamber.