IL34007A

IL34007A - Process and apparatus for producing a suspension of particles in a liquid

Info

Publication number: IL34007A
Application number: IL34007A
Authority: IL
Original assignee: Neyrpic Bmb
Priority date: 1969-03-07
Filing date: 1970-03-04
Publication date: 1972-12-29
Also published as: FI51772B; BE746374A; DE2010189A1; ES377217A1; AT298217B; IL34007A0; DE2010189B2; YU50970A; US3664096A; GB1254825A; YU33343B; FR2036249A5; FI51772C; SE360273B

Description

vf The invention relates to processes and apparatus for the homogeneous suspension of particles in a for to the production of aqueous suspensions of eellulose or textile fibres serving as a feed for continuously operated machines for the of paper or textile granular fibrous particles which are to be suspended in a are produced from natural or synthetic materials by preceding operations which impart to them the desired grain size or fiber These operations are mostly carried out in a natural and even if they are performed in the moist the particles are nearly always dried for in order to facilitate their As a the smallest hollow or however of the granular filled with and similarly the fibrils of the fibrous particles which form a kind of are filled with air at atmospheric cannot be which When the particles are contacted with the dispersing surface tension phenomena whose magnitude depends on the material of both the particles and liquid prevent the liquid from displacing the air from the aforesaid hollows and from moistening the particles Numerous air bubbles remain thus adhering to the which prevents the homogeneous dispersion of the particles and makes for their or it may even impart to them different apparent specific depending on the proportion by volume of the air which they The invention overcomes these drawbacks by facilitating the preliminary elimination of the gas which tends intimately to adhere to the According to the invention the particles are stirred in a vessel in which a state of pressure is maintained in the same are projected on the surface of a moving layer of the dispersing The invention also provides an apparatus for carrying out the process which an hermetically sealable vessel and means for producing a vacuum a arrangement disposed outside the upper part of the vessel and including at leaet one feeding mechanism disposed inside the vessel and traversing the wall of the a sealing gasket being interposed between the feeding mechanism and the wall of the vessel a hopper within the vessel beneath the feeding a stirring device within the and a rotating spreader at the bottom end of the ptacle a with large surface within the vessel beneath the spreader and coaxial with the and at least one dispersing liquid feed conduit and at least one suspension ptacle drain coordinated to the The invention is by way of example in the accompanying drawings i which 1 is a section of an apparatus according to the invention for suspending textile fibres in 2 is an axial in greater of the lower part of the T between them being tightened by a gasket The enclosure 25 is surrounded by an annular space 27 closed at the bottom by the flange 28 and at the top by the lid space 27 is connected to a vacuum conduit Within the apparatus and at a level slightly higher than the bottom end of the hopper there are disposed three concentrical sprinkler pipes 30 whose nozzles 31 are directed The dispersing liquid is fed to the pipes through a conduit 32 which passes from outside through the wall the As shown in the stirrer shaft 6 has secured to its slightly open bottom end of the hopper a scattering disc 35 with radial ribs In operation a state of pressure diminution of about bar below atmospheric pressure is maintained within the vessel 2 by a vacuum pump connected to the conduit The enclosure 25 decreases the volume of the space within the vessel 2 in whic he vacuum has to be The are d f om the hoppers 10 the hopper 4 at a rate which can be controlled by the motors In the hopper 4 the fibres are subjected to the whereby the occluded in their fibrils at normal is made to expand and its adherence to the fibres is The mechanical action of the stirrer enhances even more the liberation of the small amounts of The fibres are again subjected to a mechanical action at atmospheric pressure when they are projected centrifugaHy by the scattering disc and again by the impact of the liquid particles sprayed through the nozzles The fibres are thus brought into contact with the dispersing liquid without adherent gas particles and can thus homogeneously be dispersed in the The height of the liquid seal in the channel the difference between the levels of the liquid in the drains 21 and the surface of the fibre suspension in the channel corresponds to the pressure difference between the interior of the apparatus and the external The invention is not limited to the particular ment described above by way of and includes other embodiments differing in Thus the fibres can be the apparatus by any other device which provides a similar and the and the actuation of the stirrer may be different from the one described the fluid sprayed by the sprinkler pipes 30 need not necessarily be the same as the dispersing whatever the the sprayed liquid may be a wetting the spray may consist of the dispersing liquid either in the vapour state or as a liquid but at a temperature different of the liquid supplied throug the conduit 7 insufficientOCRQuality

Claims

1. A process for producing a suspension of particles in a liquid, wherein the particles are stirred in a vessel in which a state of sub-atmospheric 'pressure is maintained and in which the particles are projected on to the surface of a moving layer of the dispersing liquid.

2. A process according to Claim 1, wherein the particles are cellulose fibres and the disposing liquid is water.

3. A process according to Claim 1 or 2, wherein the particles are textile fibres and the dispersing liquid is water. '

4. · A process according to Claim 1, 2 or 3» wherein before contacting the surface of the moving layer of dispersing I liquid the projected particles are sprayed upon with a fluid within the vessel at sub-atmospheric pressured ί ' ■

5. ' A process according to Claim 4, wherein the sprayed fluid is the same as' the. dispersing liquid.

6. A process according to Claim 4, wherein the sprayed fluid is a wetting agent.

7. A process according to Claim 4, wherein the sprayed fluid is steam.

8. '8. 'An apparatus for carrying out the process according to Claim 1, comprising an hermetically sealable vessel and means for producing a vacuum therein; a particle-feed arrangement disposed outside the upper part of the vessel and including at least one feeding mechanism disposed inside the vessel and traversing the wall of the vessel, a sealing gasket being 34007/2 8 - stirring device within the hopper, and a rotating spreader at the bottom end of the hopper? a receptacle with large surface within the vessel beneath the spreader and coaxial with the hopper, and at least one dispersing liquid feed conduit and at least one suspension drain coordinated to the receptacle.

9. An apparatus according to Claim 8, comprising within the vessel above the spreader and concentrical with the hopper, at least one sprinkler pipe disposed to spray the fluid downwardly towards the receptacle.

10. An apparatus according to Claim 8, wherein the stirring device within the hopper comprises a vertical shaft disposed in the axis of the hopper, and substantially horizontal paddles secured to the shaft.

11. An apparatus according to Claim 10, wherein the spreader rotating at the bottom end of the hopper is a centri-fugally acting ribbed disc mounted at the lower end of the stirrer shaft.

12. An apparatus according to Claim 8, wherein the ptacle r ceiver is dish-shaped with a central pit and a broad edge ptacle sloping inwardly towards th pit, and the rece^A6©-*- is surrounded by an annular channel which overflow from the receptacle and is provided with at least one drain at a level beneath the overflow level. PC/ru