US2684728A - Apparatus for removing air from viscose solution - Google Patents

Description

July 27, 1954 L. MALM 2,684,728

APPARATUS FOR' REMOVING AIR FROM VISCOSE SOLUTION Filed May 17, 1952 INVENTOR LAWRENCE LOU/5 MALM By g AT ORNEY Patented July 27, 1954 UNITED STATES ATEN T ()F F ICE APPARATUS FOR REMOVING AIR FROM VISCOSE SOLUTION Application May 17, 1952, Serial No. 288,392

3 Claims. 1

This invention relates to an apparatus for the removal of air and other gases dissolved and entrained in liquids. More particularly, it relates to the continuous removal of air and other gases 'from viscous liquid solutions such as viscose.

In the process of preparing viscose solutions for the spinning of synthetic fibers, gas and air become entrained in such solutions in the form of bubbles. Should these gas and air bubbles be permitted to remain, broken filaments in the spun yarn would result when the viscose solution is extruded through the holes of spinnerets. Yarn thus produced has a varying number offilaments and is therefore not of uniform quality.

Various methods have been proposed to remove these gases from viscose spinning solutions. One of the methods comprises subjecting a batch of viscose in a receptacleto a vacuum. In another method the viscose solution is agitated while subjected to a vacuum. Still various other methods employ bafiies, plates, cones, etc. as means for spreading the viscose solution into a thin film with or without a supporting and flow directing surface, then subjecting such thin film of viscose to a vacuum. These aforementioned deaerating methods are generally not satisfactory since through their practice utilized apparatuses are generally frequently taken out of service for cleaning and the gases are not substantially completely removed.

In some deaerating apparatuses it is necessary to stop their operation and clean their interiors at regular intervals of adhering andhardened viscose. This is necessary because viscose on entering a tank is caused to boil because of reduced pressure created by vacuum on the tank. The boiling-action frees the entrained gases and causes spattered viscose to be carried away from the surface of the liquid and deposited on the bare walls of the deaerating chamber. This forms a skin due to the aging characteristics of the viscose liquid. This skin then builds up and impedes the flow of viscose. In the event that the deaerating apparatus is not cleaned at the proper time the hardened skin breaks away from the metal surface and falls into the viscose, subsequently tending to block pumps, controls, filters, etc.

This invention has for its purpose the provision of an apparatus which isadapted to continuously and substantially more completely degasify and deaerate a flowing viscose solution and to prevent spattered viscose from becoming fixed to the interiortank walls. The deaeration is effected by causing an initialboiling of a viscose solution and over the outer surface of the bell.

'ing of the viscose solution allows the more minute in a'limited collecting enclosure such as a channel and a trough into which the solution is initially emptied. The viscose solution is continuously fed to the channel and trough which it overflows to spread as a thin film over support ing surfaces such as the interior wall of a tank and the exterior wall of a bell shaped cylinder centrally located within the lower portion of the tank.

To prevent clinging spattered viscose a jacket is placed about the upper portion of the viscose deaerating tank. A cooling fluid is pumped through an inlet, into the jacket, circulated through the jacket, and then it is forced out through an outlet. The tank walls are wettcd by the condensation of rising vapors. A suf ficient quantity of cooling medium at a desired temperature to produce condensation of water vapors on the walls of the-deaerating chamber is circulated through the ja set, the condensed vapors return by gravity as a water film to the main body of the flowing liquid viscose, and whatever spattered viscose hits this flowing film of condensed water it is diluted on contact and also returned to the main liquid viscose body. Spattered viscose does not remain on the tank wall but flows downwardly to rejoin the main viscose body. An additional advantage is that no additional dilution is, generally, required to compensate forthewater boiled off during the deaeration since the water vapor is returned as condensate to the viscose solution. Also, condensation of the water vapors and the return of the condensatelowers the requirement in vacuum pump capacity resulting in lower cost operation.

In removal of entrained gas and air bubbles from the viscose solution a boiling and subsequent thinning of the viscose solution frees entrained gases which are being continuously evacuated. The more deeply entrained gas bubbles are yielded as the solution overflows a channel and trough as a film which is spread in a flowing thin layer on the inner surface of the tank The filmbubbles to .escape since their entrainment is in a thin layer and they are closer to the surface of the viscose so as to be more easily drawn out by the vacuum within the tank. There is provided, further, a second channel below the first mentioned channel to effect a repeated filming of the solution a second time to remove gases not already given up. Attached to this second channel there may be provided a baffle plate to collect viscose that may become spattered dur ing the initial boiling. The bafiie redirects such spattered viscose to the flowing stream along and against the inner wall of the tank.

The invention will be better understood by reference to the following description and accompanying drawing wherein the deaerating apparatus is shown in section.

As shown in the drawing the deaerating apparatus comprises an enclosed tank In having a cylindrical intermediate portion ll enclosed by a tank top i2 and tank base l3.

In the tank top I2 there is positioned a viscose inlet conduit [6 which extends substantially into the tank interior. Positioned within the tank l and at its upper portion is a viscose distribution manifold ll which is attached to the viscose inlet conduit l5. Projecting from the distribution manifold H are a plurality of laterally extending viscose distribution tubes i8, and a downwardly extending tube H9. The distribution tubes I8 have outlets in channel 38, and tube 19 extends into trough 45.

In order to facilitate the removal of the air bubbles and gases from the viscose a vacuum and it is controlled at a point depending upon the vacuum applied which permits a boiling of the viscose through a predetermined temperature range. This boiling action removes readily releasable gases from the viscose, as well as some water vapor.

Positioned about the top portion of the tank It is a jacket as having a cooling medium inlet pipe 25 and an outlet pipe 25. In the space 2'! there is circulated a cooling medium. The cooling medium cools the upper portion of the tank it, the cooled inner walls chill the vapor in the withdrawn gases to form a condensate on the inner wall of the tank wetting the wall, preventing the accumulation of spattered viscose and lubricating the wall surface.

Positioned in the upper portion on the interior of the tank H} is the channel 39. Channel as is formed by the inner Wall of tank cylinder l i! and a frustum of a cone 3! with its diverging portion 32 in contact with the inner tank wall of the tank cylindrical portion l. Positioned below the first channel 39 is a second channel 35 formed in a like manner. The second channel 35 also has the diverging portion 3'! of the frustum of a cone 3% contactin the inner wall of the it tank cylinder H. Attached to the second channel 35 is a baiile 33, also shaped as a frustum of a cone. The baffle as is spaced from the second channel 35 being supported by hangers ll and it is positioned with its diverging portion Ail placed into close proximity to the diverging portion 37 of the second channel 35 and of the inner wall of tank cylinder ll.

Resting in the base it of the tank iii is a bell A4 formed in such a manner so as to facilitate the spreading of viscose by means of a curved surface. At the top portion of the bell 44 there is positioned a circular trough $5. In the base of the bell 44 and in the vertical sides fill, are a plurality of openings 46. These openings allow the viscose to flow through the screen as to the viscose outlet 5! in the base l3 of tank It.

In the continuous operation of the deaerating apparatus comprising this invention viscose is fed to the tank through the viscose inlet conduit l6 and flows to the viscose distribution manifold IT. From the manifold H the viscose passes through distribution tubes 18 to the channel at the upper portion of the tank. The viscose overflows the converging edges of the frustum of a cone SI of the channel 39) and flows downwardly in the form of a film and continues downwardly along the inner wall of tank cylinder l I. In its flow from the upper annular trough 30 the viscose solution tends to divide and to collect into separate but considerably thicker streams rather than as a uniformly thin cylindrical flowing stream. Bafile 39 serves to again spread and unify the various streams into a thin film. The viscose solution that flows into the trough formed by the bafile and the wall of the tank i0 flows out through the base opening as a single thin cylindrical stream of tank I0. The flow of viscose continues downwardly until it reaches the second channel where, again, the viscose is caused to overflow the converging edges of the frustum of a cone 36 in the form of a thin film of liquid. The deaerated viscose solution then flows downwardly along the inner wall of the tank cylinder l i to the tank base it, and through the screen 50, and out through the viscose outlet 5|.

Simultaneously with the feeding of viscose into the upper channel 30 viscose is also continuously fed from the manifold I? through the distribution tube is into the trough on the viscose spreading bell 44. The viscose overflows the trough 45 and flows in a spreading manner downwardly along the walls 4! of the bell 44 in the form of a thin film releasing gas and air bubbles. The film of viscose flowing along the wall of the bell proceeds downwardly until it reaches the base of the bell 44 and then flows through the holes 46 at the base of bell walls 4! and then through the screen 58 into the viscose outlet 5 l.

The interior of the tank is is made accessible through the side manhole cover 54. Further, the deaeration process can be checked by means of sight glasses 55, 56 positioned in the side of the tank at below the first channel 38 and at about below the top of the bell 44.

I claim:

1. A continuous viscose deaerating apparatus comprising; a tank, a jacket about the upper portion of said tank, a cooling medium circulating through said jacket, said cooling medium cooling the upper portion of said tank forming a condensate to wet the inner wall, means for placing a vacuum on said tank, a viscose inlet conduit extending into said tank, a viscose outlet in the base of said tank, a plurality of distribution tubes associated with said viscose inlet conduit, a channel in said tank at substantially its upper portion, said channel being formed by the inner tank wall and a frustum of a cone, a viscose spreading device having a generally cylindrical body portion with an enclosed top being centrally located within the lower portion of said tank, said device having on its top portion a circular trough, and said plurality of distribution tubes extending into said channel and into said circular trough for continuously supplying viscose thereto, said viscose simultaneously overflowing said channel and said trough forming a film and flowing downwardly along the inner surface of said tank and along the outer surface of said device to the outlet at the base of said tank.

2. A continuous viscose deaerating apparatus comprising; a tank, a jacket about the upper portion of said tank, a cooling medium circulating through said jacket, said cooling medium cooling the upper portion of said tank forming acondensate to wet the inner wall, means for placing a vacuum on said tank, a viscose inlet conduit extending intosaid tank, a viscose outlet in the base of said tank, a plurality of distribution tubes associated with said viscose inlet conduit, a channel in said tank at substantially its upper portion, said channel being formed by the inner tank wall and a frustum of a cone, a second like channel positioned below said first channel, a viscose spreading device having generally cylindrical body portion with an enclosed top being centrally located within the lower portion of said tank, said device having on its top portion a circular trough, said distribution tubes extending into said first channel and into said circular trough for continuously supplying viscose, said viscose overflowing along the outer surface of said first channel forming a film and flowing downwardly along the inner surface of said tank then into said second channel and filmed a second time in a like manner, said viscose flowing to said outlet at the base of said tank, simultaneously said viscose overflowing said circular trough of said device is formed into a film which flows downwardly along the outer surface of said device to said outlet at the base of said tank.

3. A continuous viscose deaerating apparatus comprising; a tank, a jacket about the upper portion of said tank, a cooling medium circulating through said jacket, said cooling medium cooling the upper portion of said tank forming a condensate to wet the inner wall, means for placing a vacuum on said tank, a viscose inlet conduit extending into said tank, a viscose outlet in the base of said tank, a plurality of distribution tubes associated with said viscose inlet conduit,

a channel in said tank at substantially its upper portion, said channel being formed by the inner tank wall and a frustum of a cone, a second like channel positioned below said first channel, a baffle formed as a frustum of a cone attached to said outer surface of said second channel, a viscose spreading bell centrally located within the lower portion of said tank, said bell having on its top portion a circular trough, said distribution tubes extending into said first channel and into said circular trough for continuously supplying viscose, said viscose overflowing along the outer surface of said first channel forming a film and flowing downwardly along the inner surface of said tank then into said second channel and filmed a second time in a like manner, said viscose flowing to said outlet at the base of said tank, simultaneously said viscose overflowing said circular trough of said bell is formed into a film which flows downwardly along the outer surface of said bell to said outlet at the base of said tank, said baffle collecting spattered viscose overflowing said channels and redirecting said viscose to said tank inner wall and said outlet at the base of said tank.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,556,098 Gibson Oct. 6, 1925 2,041,059 French May 19, 1936 2,146,532 Crane et al Feb. '7, 1939 2,355,057 Copeland Aug. 8, 1944 2,408,021 Hill Sept. 24, 1946 2,498,836 Cross Feb. 28, 1950 2,515,648 Hunt et a1 July 18, 1950

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