US2920761A

US2920761A - Apparatus for separating and deaerating pulp suspension

Info

Publication number: US2920761A
Application number: US331062A
Authority: US
Inventors: Freeman Horace; John D Boadway
Original assignee: Nichols Engineering and Research Corp
Current assignee: Nichols Engineering and Research Corp
Priority date: 1952-09-24
Filing date: 1953-01-13
Publication date: 1960-01-12
Anticipated expiration: 1977-01-12

Description

Jan. 12, 1960 R M ETAL 2,920,761

'APPARATUS FOR SEPARATING AND DEAERATING PULP SUSPENSION Filed Jan. is. 1955 MCUUM DISCHA E65 72 VACUUM PUMP INVENTORS. Hon/a CE fkEEMA/M BY JOHN D. BOADWAK 6; y M 1 ATTOAMEKS'.

BnROMETR/C LEG cw TO Sucrlou PUMP search Corporation, New York, N.Y., a corporation of Delaware Application January 13, 1953, Serial No. 331,062

1 Claim. (Cl. 209-211) This invention relates to methods and apparatus for separating gases, vapor and solid particles such as dirt from liquids and liquid suspensions, the invention among various other possible uses being adapted for the treatment of paper pulp suspensions.

' Vortex type separator devices for separating dirt from paper pulp suspensions have heretofore been used of a construction comprising an elongated very gradually tapered conical chamber into which the suspension is forced tangentially at the larger end so as to form a vortexof gradually decreasing diameter extending toward the smaller or apex end of the chamber, portions of the vortex reversing and running back to form an inner v'ortex from which the treated stock is withdrawn axially from within the larger end, while a small portion of the stock together with the dirt particles is discharged from the other'and quite small apex end.'

The present invention involves certain modifications in the construction of and method of operating apparatus of the general type above referred to and which will adapt the same for use for effectively separating from the liquid .or suspension dissolved and occluded gases, bubbles and froth as well as the dirt particles.

As heretofore proposed, separators of the type above referred to were not adapted for removing gases or vapors in any of these various forms. In such devices as heretofore operated a small hollow gas core would normally exist at the center of the vortexes, but if the apex or dirt outlet was placed in free communication with the atmosphere then such hollow core would be maintained at atmospheric pressure and thus there would be no effect in the vortexes such as required to liberate the dissolved or occluded gases from the liquid of the vortexes, and such bubbles and froth as might accumulate along within the hollow core would be largely carried out in the outgoing stream of treated stock and thus not separated therefrom. On the other hand, if the apex or dirt outlet of such separators were immersed in a body of liquid, while there might be a tendency for a slightly sub-atmospheric pressure to occur within the hollow core due to the removal of air bubbles along with and in the stream of treated stock, yet any dissolved or occluded gas which might tend to come into such hollow core by reason of any such sub-atmospheric pressure would be all carried out along with and still in admixture with the stream of treated stock or with the small stream of rejected dirt-containing stock passing out through the apex opening, thus still leaving no chance for separation of gases from the suspension, and in fact as a result of the agitation of the suspension the froth and bubbles therein would tend to increase.

Another proposal has been to withdraw both the treated stock stream and the rejected dirt-containing stream from this type of device and to pump such streams to secondary cleaners and thence to the paper machines, but here again the outgoing streams would embody all of the gas originally contained in the suspension.

With the present invention on the other hand the United States Patent greater part of the gases and vapors in their various forms in the suspension may readily'be removed without interfering with the dirt-separating functions of such ap paratus.

Various further and more specific objects, features and advantages of the invention will appear from the detailed description given below taken in connection with the accompanying drawing which forms a part of this specification and illustrates merely by way of example, one form of apparatus for the practice of the invention. The invention consists in such novel features, arrangements and combinations of parts and method steps as may be shown and described herein.

In the drawings, the single figure is a vertical sectional view of the apparatus of the invention.

The suspension or liquid mixture to be treated'is admitted under pressure through inlet 10 tangentially into a cylindrical upper end portion 11 of the separating cham-.v

outlet 17 where with a small amount of the stock, same will be discharged into an enclosed chamber 18.

This chamber or enclosure 18 as indicated, is brought into communication by a pipe 19 with a suitable vacuum pump and such enclosure is so designed and arranged that it will normally be partially filled, as indicated, with the discharged dirt-containing suspension. The under side of the chamber 18 is connected by a pipe 20 either to a barometric leg or to a suitable suction pump such as will insure discharge of the rejected stock from the chamber at about the same rate as the discharge of such stock from the conical chamber above.

Thus it will be seen that the small elongated hollow core 15 in the vortexes may, by means of the evacuated chamber 18 be maintained constantly under a low subatmospheric pressure preferably a pressure about equal to the normal vapor pressure of the suspension being treated in chamber portion 13, or for example from 4 to 8 cms. Hg absolute.

Hence dissolved and occluded gases within the vortexes in the conical chamber portion 13 will tend strongly to be liberated from Within the liquid nearest the hollow core 15 because of such sub-atmospheric pressure, and such liberated gases as well as vapor present in the hollow core and the gas contained in any bubbles or froth which will be forced into the hollow core will be constantly evacuated downwardly through the hollow core to the enclosure 18 and out to the vacuum pump.

Meanwhile the treated stock embodied in the upward return vortex 14 will pass out through the central outlet 21 at the upper end and may be withdrawn therethrough by applying to the outlet connection 22 any suitable evacuating device such as a barometric leg or suction pump.

While because of the evacuated condition maintained in the core 15 and the constant rapid withdrawal of gases therefrom into the enclosure 18 will insure that most of the gas in the suspension will be evacuated through the connnection 19 to a vacuum pump, yet some bubbles may be carried out along with the treated stock through the connection 22, and if desired same, if sufiicient in quantity to be objectionable, may be separated by running the stock through a supplemental froth-separating chamber in the manner disclosed in our co-pending ap- Other: Fluids, and now abandoned in favor of "Serial No. 324,561, filed December'o, 1952, issued as Patent No. 2;849;930 on- September 2, 1958, entitledL-Method and Apparatus for Treating Pulp Suspensions and ther. Fluids for Removal of Undesired Particles and Gases, reference-to which is hereby made, for a more'detailed explanation of various aspects of the invention. In said application certain phases of the invention as well as alternative embodiments are. broadly claimed and other alternative embodiments are disclosed'and claimed inour co-pending application, Serial No. 425,942, filed April 27, 1954', issued as Patent No. 2,757,582, on August 7; 1956.

Although one embodiment of the invention is herein disclosed for purposes of explanation, various modifications thereof, after study of this specification, will be apparent to those skilled'in the art to which the invention pertains. Reference should accordingly be had to the appended claim in determining the scope of the invention.

What is claimed and desired to be secured by Eetters Patent is:

Apparatus for separating gas, dirt particles and the like from liquid pulp suspensions which comprises: an elongated chamber of circular internal cross-section; a liquid inlet connection positioned to discharge the suspension tangentially into one end of said chamber for maintaining a helical flow about the inside walls of the chamber'and surrounding a gas core extending throughout the length of the chamber, portions at least of said chamber which are adjacent the end thereof opposite from said" inlet connection being of gradually restricted diameter terminating in a relatively small outlet, there by to cause the larger part of such helical flow to reverse and to extend back toward the inlet end of the chamber as an inner vortex also surrounding the gas core; an outlet conduit for the desired treated suspension communieating with the central portion of .the'inlet end of said chamber and concentric with said small outlet; a second chamber closed to the atmosphere and into which said small outlet freely communicates to discharge into such second chamber the outer. portion of the helical flow surrounding the gas core and containing said dirt particles; means for withdrawing the dirt containing liquid from said second chamber to maintain the liquid level therein below said small outlet; and vacuum pump means connected to said second chamber at a point above said liquid level for separately evacuating gas from above the level of said liquid received in said secondchamber andacting to maintain said second chamberunder low subatmospheric pressure and also continuously to evacuate the contents of said gas core throughthe middle-of said small outlet and to discharge such 'gas from'the second chamber, thus maintaining said gas core also under low subatmospheric pressure.

References Cited in the file of this patent UNITED STATES PATENTS 2,102,525 Freeman .Dec. 14, 1937' 2,377,524 Samson June 5, 1945 2,571,219 De Cew Oct. 16, 1951 2,614,656 Clark .Oct. 21, 19.52 2,642,950 Clark June 23, 1953. 2,685,937 Clark Aug, 10,1954 2,878,934 Tomlinson Mar. 24, 1959