Patent GB-722888-A (GB)
Title: Improvements in or relating to the production of viscose
IPC: D01D1/10
Filed: 1952-02-07
Abstract: <PICT:0722888/IV (a)/1> <PICT:0722888/IV (a)/2> <PICT:0722888/IV (a)/3> <PICT:0722888/IV (a)/4> <PICT:0722888/IV (a)/5> <PICT:0722888/IV (a)/6> A continuous de-aerator for viscose comprises a vertical vessel, the walls of at least the upper part of which slope inwards from the top downwards, a pipe leading from the vessel through which air can be withdrawn from the vessel to maintain a reduced pressure therein, means for feeding viscose into the vessel continuously at all points round its periphery so that the viscose forms a thin film on the inner wall of the vessel, and means for withdrawing viscose from the lower part of the vessel.  As shown in Fig. 1, viscose flows from the conduit 23 through the orifice plate 28, manifold 24 and conduits 25 into the annular passage-ways 26 (Figs. 1 and 2) and through the narrow annular passage-way 22, by means of which it is fed directly on to the inner surface of the inwardly sloping wall of the vertical, generally cylindrical, vessel 10 round its entire periphery.  The viscose then flows in a thin film down the wall of the vessel 10 and collects in a pool 27 in its lower portion.  The interior of the vessel 10 is maintained at a reduced pressure, the conduit 15 in the cover 12 being connected with an exhauster (not shown), and the gas bubbles dispersed in the viscose film together possibly with some of the dissolved gases and water are thereby removed. The orifice plate 28 in the conduit 23 serves to maintain the pressure of the viscose in the conduit 23 and to prevent premature boiling.  The pool of viscose 27 is illuminated by a beam of light from a source (not shown) outside the de-aerator passing through a rod 29 of a material (e.g. methyl methacrylate polymer) having a high index of refraction, so that the viscose may be examined for freedom from gas bubbles as it passes the viewing port 30 on its way to the outlet.  When a substantial proportion of water boils off from the viscose in the vessel 10, the resultant temperature drop may be employed to control the degree of vacuum in the de-aerator and thus the amount of boiling which takes place. This is effected by the passage of the incoming viscose over a thermo-element 31 in the conduit 23 and a thermo-element 32 in a cup 33 (provided with a drainage opening 34) attached to the wall of the vessel 10 slightly above the surface of the pool of viscose 27.  The thermo-elements 31, 32 are connected to a controller (not shown) which, when the viscose flowing down the vessel 10 becomes too cool (showing excessive boiling), opens a valve (not shown) admitting steam into the vacuum line and thus lowering the degree of vacuum.  A cover 12 is bolted to the top of the vessel 10 and is provided with a skirt 16, the wide clearance between the upper part 18 of which, and the wall of the vessel 10, forms the annular passage-way 26.  The lower part 20 of the skirt 18 is slightly and uniformly spaced from the wall of the vessel 10 by spacers 21, and the clearance between the part 20 of the skirt and the wall of the vessel 10 forms the narrow annular passage-way 22. In the modification shown in Figs. 3-6, mounted on the upper end of a vertical, generally cylindrical, vessel 41 is a flanged collar 42, 43 on which is seated a fitting 44 comprising a body part 45 having a downwardly opening passage-way 46 extending round its entire circumference, the passage-way being bounded on its inner side by a downwardly-extending skirt 47.  The latter extends below the level of the flange 43, and is slightly spaced from the collar 42 so as to form with it a narrow passage-way 49 opening downwardly into the vessel 41.  A cover 52 fastened to the fitting 44 closes the vessel 41, and a vacuum line 53 opens into the cover 52.  The viscose is fed to the de-aerator through the conduit 54 (Figs. 3 and 4) into a manifold 56 that distributes it to four entrance conduits 57 extending through the flange 43 at four points spaced uniformly round its periphery and opening into the passage-way 46, whence it flows down through the narrow passage-way 49 on to the wall of the vessel 41.  To distribute the viscose uniformly about the entire periphery of the wall of the vessel 41, the annular passage-way 46 is contoured so that its cross-sectional area is greatest at the points where the viscose is introduced through the conduits 57 (Figs. 4 and 5), and decreases gradually until it reaches a minimum at a point mid-way between each pair of conduits (Figs. 4 and 6).  De-aerators according to the invention are suitable for use in the process of Specification 722,827.ALSO:<PICT:0722888/III/1> <PICT:0722888/III/2> <PICT:0722888/III/3> <PICT:0722888/III/4> <PICT:0722888/III/5> <PICT:0722888/III/6> A continuous de-aerator for liquids such as viscose comprises a vertical vessel, the walls of at least the upper part of which slope inwards from the top downwards, a pipe leading from the vessel through which air can be withdrawn from the vessel to maintain a reduced pressure therein, means for feeding the liquid into the vessel continuously at all points round its periphery so that the liquid forms a thin film on the inner wall of the vessel, and means for withdrawing the liquid from the lower part of the vessel.  As shown in Fig. 1, the liquid flows from the conduit 23 through the orifice plate 28, manifold 24, and conduits 25 into the annular passage-ways 26 (Figs. 1 and 2) and through the narrow annular passage-way 22, by means of which it is fed directly onto the inner surface of the inwardly sloping wall of the vertical p generally cylindrical vessel 10 round its entire periphery.  The liquid then flows in a thin film down the wall of the vessel 10 and collects in a pool 27 in its lower portion.  The interior of the vessel 10 is maintained at a reduced pressure, the conduit 15 in the cover 12 being connected with an exhauster (not shown), and the gas bubbles dispersed in the liquid film together possibly with some of the dissolved gases and water are thereby removed. The orifice plate 28 in the conduit 23 serves to maintain the pressure of the liquid in the conduit 23 and to prevent premature boiling.  The pool of liquid 27 is illuminated by a beam of light from a source (not shown) outside the de-aerator passing through a rod 29 of a material (e.g. methyl methacrylate polymer) having a high index of refraction, so that the liquid may be examined for freedom from gas bubbles as it passes the viewing port 30 on its way to the outlet.  When a substantial proportion of water boils off from the liquid in the vessel 10, the resultant temperature drop may be employed to control the degree of vacuum in the de-aerator and thus the amount of boiling which takes place.  This is effected by the passage of the incoming liquid over a thermo-element 31 in the conduit 23 and a thermo-element 32 in a cup 33 (provided with a drainage opening 34) attached to the wall of the vessel 10 slightly above the surface of the pool of liquid 27.  The thermo-elements 31, 32 are connected to a controller (not shown) which, when the liquid flowing down the vessel 10 becomes too cool (showing excessive boiling), opens a valve (not shown) admitting steam into the vacuum line and thus lowering the degree of vacuum.  A cover 12 is bolted to the top of the vessel 10 and is provided with a skirt 16, the wide clearance between the upper part 18 of which, and the wall of the vessel 10, forms the annular passage-way 26.  The lower part 20 of the skirt is slightly and uniformly spaced from the wall of the vessel 10 by spacers 21, and the clearance between the part 20 of the skirt and the wall of the vessel 10 forms the narrow annular passage-way 22.  In the modification shown in Figs. 3-6, mounted on the upper end of a vertical, generally cylindrical, vessel 41 is a flanged collar 42, 43 on which is seated a fitting 44 comprising a body part 45 having a downwardly opening passage-way 46 extending round its entire circumference, the passage-way being bounded on its inner side by a downwardly extending skirt 47.  The latter extends below the level of the flange 43, and is slightly spaced from the collar 42 so as to form with it a narrow passageway 49 opening downwardly into the vessel 41.  A cover 52 fastened to the fitting 44 closes the vessel 41, and a vacuum line 53 opens into the cover 52.  The liquid is fed to the de-aerator through the conduit 54 (Figs. 3 and 4) into a manifold 56 that distributes it to four entrance conduits 57 extending through the flange 43 at four points spaced uniformly round its periphery and opening into the passage-way 46, whence it flows down through the narrow passage-way 49 on to the wall of the vessel 41.  To distribute the liquid uniformly about the entire periphery of the wall of the vessel 41, the annular passage-way 46 is contoured so that its cross-sectional area is greatest at the points where the liquid is introduced through the conduits 57 (Figs. 4 and 5), and decreases gradually until it reaches a minimum at a point mid-way between each pair of conduits (Figs. 4 and 6).