US2682772A

US2682772A - Sampling device

Info

Publication number: US2682772A
Application number: US337201A
Authority: US
Inventors: Herbert T Peterson
Original assignee: Weyerhaeuser Timber Co
Current assignee: Weyerhaeuser Timber Co
Priority date: 1953-02-16
Filing date: 1953-02-16
Publication date: 1954-07-06
Anticipated expiration: 1971-07-06

Description

H. T. PETERSON SAMPLING DEVICE Juy 6, 1954 Filed Feb. 16, 1955 Patented July 6, 1954 UNITED STATES PATENTy ortica SAMPLING DEVICE Herbert T. Peterson; Longview, Wash., assignor to Weyerhaeuser; Timber Company, Longview, Wash., a.. corporation of Washington Application February 16, 1953, Serial No. 337,201

(Cl.` 'Z3-424) 9 Claims. 1

This invention relates` to sampling devices, and provides an' improved rotating screw sampling device for obtain-ing a continuous sample of both the liquid and solid phases of high-consistency pulps from vessels in which such pulps are contained under substantial superatmospheric pressure.

Many manufacturing processes, particularly those or a chemical natu-re, require close and substantially continuous control of operating conditions. In such processes it is often necessary to obtain frequent or continuous samples of the material being processed for purposes of analysis and control. For example, in the manufacture of cellulose from wood pulp, it is desirable to make frequent o-r continuous pH or other determinations on the liquid component of cellulosic pulps undergoing treatment, and it is also desired sometimes to make tests on the pulp nbers. It is difficult, however, to provide for continuous or frequent withdrawal of small test samples of such pulps, especially when they are of high consistency andY are being processed at high pressures. Y

I have devised an improved sampling device for continuously withdrawing a small sample of the liquid component of high consistency pulps, which sample also contains a smallV proportion' of the solid component of the pulp. The new sampling device comprises a rotating screw Aelement mounted for rotation within a sampling tube having an inlet opening at its outer end and a discharge openingr at its inner end. The rotating screw element comprises a shaft which is provided with inner and outer helical screw flights of opposite pitch. The outer helical lscrew night is disposed on the shaft adjacent the inlet opening of the sampling tube, and the inner' helical screw night is disposed on the shaft adjoining the outer screw night and extending along the shaft toward the discharge opening of the tube. Means are provided for rotating the shaft in the direction which causes' the outer helical screw night to appear to travel outwardly, whereby excessiveaocumulation of solid material at the inlet opening of the sampling tube is prevented. Simultaneously the inner helical screw flight appears to travel toward the discharge opening of the tube, and thereby it propels toward such discharge opening the small sample of stock liquor and pulp fibers which work their way pastv the outer screw,V night.

The rotatable shaft of the rotating screw element advantageously is. mounted for reciprocating movement along its longitudinal axis and is provided with means for moving it back and forth within the sampling tube. Thev reciprocating motion thus imparted to the shaft and screw nights is effective for keeping the inlet opening of the sampling tube free from solid material, which otherwise would accumulate there and clog the tube, even when the pulp4 is of very high consistency and is being processed at. high pressure.

A particularly advantageous embodiment oi the new samplingl device is described below in connection with the accompanying drawings, in

which:

Fig. l is a longitudinal section through the .new sampling device;

Fig. 2 is a top view of one end of the device showing the reciprocating mechanism at one limitof its travel, and

Fig. 3 is a cross section taken substantially along the line 3 3 of Fig, 2.

The sampling device comprises a samp-ling tube I@ having an inlet opening ii at its outer end and a dischargeopening. i2. at its inner end. A shaft I3 is mounted for rotation about vand for reciprocating movement alongk its longitudinal axis within the sampling tube In. `The sha-it i3 lis provided with outer andinner helical screw responds to a right-hand screw thread. and the l other night lli corresponds to a left-hand screw thread. The'outer helical screw le is disposed on the shaft i3 adjacent the inlet opening il, and projects slightly therebeyond. The pitch of the screw night is advantageously not very steep, and it comprises rather few complete turns. The inner helical screw night l5 extends along the shaft i3 from the inner end of the outer night about to the discharge opening l2 of the sampling tube Ill. The pitch of this inner screw night is advantageously somewhat steeper than that of the outer night, and of course it comprises a sufficient number of turns to extend from where it adjoins the outer night to the discharge opening of the tube I9.

The discharge opening l2 of the sampling tube I0 communicates with a sample collection cham.- ber I6. This chamber is provided with a nipple Il through which liquid delivered into the chamber I6 through the tube i'may be withdrawn. A tapped access opening I8, into which a vent pipe or other device may be threaded, is provided in the upper portion of the collection chamber I6. A bearing support l@ is attached to the wall of the collection chamber opposite the 3 sampling tube I0, and a bearing 20 is mounted therein. The bearing support i may advantageously be provided with a lubrication fitting 2l, and, if desired, with a packing and packing nut 22.

The shaft I3 extends inwardly through the discharge opening I2, across the collection chamber I6, and through the bearing 2li, and is rotated by a motor 25. The motor is connected to tne shaft by means of a coupling collar '25, a coupling liange 2l and coupling pins 28. The coupling collar 26 is secured to the end of the shaft I3 by a set screw 29, and the coupling flange :il is secured to the motor shaft by a set screw 30. The coupling pins 28 are rigidly fixed to the coupling collar 26 and extend through holes in the coupling nange 2. The motor 25 rotates in the direction which causes the inner helical screw night to appear to travel inwardly toward the discharge opening I2 and which causes the outer helical screw night i4 to appear to travel outwardly toward th-e inlet opening Il of the sampling tube I. This is the direction of rotation which causes the inner night I5 to cause material to move through the sampling tube I5 toward the discharge opening I2 thereof.

In addition to means for rotating the shaft, a mechanism is provided to cause the shaft I3 to reciprocate back and forth along its longitudinal axis. The reciprocating mechanism shown comprises a peripheral cam groove 33 formed in the outer surface of the co-upling collar 26, a fixed collar 34 surrounding the coupling collar, and a cam follower 35 held by the nxed collar and riding in the cam groove 33. The cam groove 33 extends completely around the coupling collar 26, and follows an elliptical path lying in a plane disposed at an angle other than perpendicular to the longitudinal axis of the shaft i3. The nxed collar 33 is secured to support brackets 3S which .maintain it in a fixed position. The cam follower 35 advantageously is a hard steel ball received in a hole drilled in the nxed collar and held in place by a set screw 3l. As the coupling collar 23 is rotated by the motor 25, the cam follower 35, traveling in the elliptical cam groove 33, causes the coupling collar to move back and forth. The reciprocating motion thus imparted to the coupling collar 26 causes the shaft I3 and its ,associated helical screws to move bacx and forth within the sampling tube as the shaft rotates. The coupling collar and the shaft are shown in Fig. 1 to be at the innermost limit of travel of their back and forth movement, while Fig. 2 shows the coupling collar and shaft, having been rotat-ed one-half revolution, at the outermost limit of their travel.

To use the sampling device, the outer end Il of the sampling tube It is inserted into the slurry or pulp to be sampled. When the device is inserted through an opening in the wallof the vessel containing such slurry or pulp, an adapter plug 38 and packing nut 33 may be provided to make a leak-tight joint between the wall of the vessel and the outside of the sampling tube. As

vthe motor 25 rotates the shaft I3, the outer screw night I4 holds the bulk of the solid material away from the inlet opening II of the sampling tube.

Some of the liquid component of the pulp, however, nnds its way past the threads of the outer screw night I4 and reaches the inner helical screw I5. Thereupon the inward travel of the threads of the inner screw I5 conveys it rapidly to the collection ychamber I6. The sample thus collected generally contains a small quantity of the Lil solid component of the pulp, but it is free from contain enough of the solids to permit performing control or other tests thereon.

'lhe combination of outward travel of the threads or' the outer helical screw flight ifi, and the back and forth motion of the shaft and helical screw nights carried thereby, prevents the accumulation of an excess of solid material about the inlet opening II of the sampling tube i5, and thereby prevents clogging of the tube with such accumulation. The over-all length of the outer screw night it should be at least equal to and preferably somewhat greater than the stroke of the shaft I3, so that the reciprocating movement of the latter does not at any time bring the inner screw flight I5 to beyond the inlet opening il.

Sampling devices constructed in accordance with my invention have been successfully used to obtain continuously samples of the sulnte stock liquor from high density cellulosic pulps. One

such sampling device used for this purpose was provided with inner and outer helical screw nights of opposite pitch, as described above, but had no provision for reciprocating movement of the screw nights along the longitudinal axis of the sampling tube. This sampling device has been used successfully to obtain samples of sulnte liquor from pulps having a consistency up to 6% by weight of cellulosic nbers. Another sampling device according to my invention, constructed as described above with mechanism for reciprocating the shaft along its longitudinal axis, has been used successfully to obtain samples of the stock liquor `from pulps containing up to 16% of cellulosic nbers and maintained at pressures in excess of 1G@ pounds per square inch. With pulp mixtures of the latter consistency, there has been heretofore no satisfactory way to obtain samples of the liquor more or less continuously for pH Control of the pulp. With my sampling device, however, such samples may readily be obtained, and without interruption due to clogging of the sample tube with an accumulation of pulp or other solid material.

I claim:

l. A sampling device of the character described comprising a sampling tube adapted to be mounted with one end extending into the material to be sampled, a shaft extending through said tube and mounted for rotation therein, a first helical screw flight disposed on said shaft adjacent the inlet end of the sampling tube, a second helical screw night of opposite pitch to said nrst night disposed on the shaft adjoining said first flight and extending along the shaft toward the discharge end of said tube, and means for rotating said shaft in the direction to cause said nrst screw night to urge material outwardly away from the inlet opening of the sampling tube and said second screw night to convey material to the discharge opening of said tube.

2. A sampling device of the character described comprising a sampling tube adapted to be mounted with one end extending into the material to be sampled, a `shaft extending axially through said tube, said shaft being mounted for rotation about and for linear movement along its longitudinal axis, a first helical screw night disposed on said shaft adjacent the inlet end of the sampling tube, a second helical screw night of opposite pitch to said nrst night disposed on the shaft adjoining said first night and extending therefrom toward the discharge end of said tube, means for rotating the shaft and screw nights thereon,

and reciprocating means for moving the shaft back and forth along its longitudinal axis.

3. A sampling device ofthe character described comprising a sampling tube adapted to be mounted with one end extending into the material to be sampled, a shaft mounted for rotation within said tube, said shaft carrying inner and outer helical screw nights of opposite pitch, the outer helical screw night being disposed on the shaft within the sampling tube adjacent the sample inlet end thereof and the inner helical screw flight being disposed on the shaft adjoining said outer flight and extending along said shaft toward the sample discharge end of said tube, and means for rotating the shaft in the direction to cause said inner screw night to move material toward the sample discharge end of said tube.

4. A sampling device of the character described comprising a sampling tube adapted to be mounted with one end extending into the material to be sampled, a shaft extending through said tube and projecting slightly beyond the sample inlet end thereof, said shaft carrying inner and outer helical screw nights of opposite pitch, the outer helical screw flight being disposed on said shaft adjacent the inlet end of the sampling tube and extending from within the tube to slightly beyond said end, and the inner helical screw flight being disposed on the shaft adjoining said outer screw flight and extending along said shaft toward the sample discharge end of said tube, and means for rotating the shaft in the direction to cause said inner helical screw night to move material toward the sample discharge end of said tube.

5. A sampling device in accordance with claim 4 in which the pitch of the outer helical screw night is less steep than the pitch of the inner helical screw night.

6. A sampling device of the character described comprising a sampling tube adapted to be mounted with one end extending into the material to be sampled, a shaft mounted axially within the sampling tube for rotation about and for reciprocating movement along its longitudinal axis, said shaft carrying inner and outer helical screw flights of opposite pitch, said outer helical screw flight being disposed on the shaft adjacent the sample inlet end of the sampling tube and said inner helical screw flight being disposed on the shaft adjoining said outer screw night and extending toward the sample discharge end of said tube, means for rotating the shaft in the direction to cause said inner helical screw night to move material toward the sample discharge end of said tube, and means for simultaneously reciprocating the shaft back and forth along its longitudinal axis.

7. A sampling device of the character described comprising a sampling tube adapted to be mounted with one end extending into the material to be sampled, a shaft mounted axially within the sampling tube and projecting slightly beyond the sample inlet end thereof, said shaft carrying inner and outer helical screw nights of opposite pitch, said outer helical screw flight being disposed on the shaft adjacent the sample inlet end thereof and projecting slightly beyond said end and said inner helical screw flight being disposed on the shaft adjoining said outer screw night and extending towardthe sample discharge end of said tube, means for rotating the shaft in the direction to cause said inner helical screw night to move material toward the sample discharge end of said tube, and means for simultaneously reciprocating the shaft back and forth along its longitudinal axis.

8. A sampling device according to claim 7, in which the length of the outer helical screw night is greater than the length of the stroke of the reciprocating shaft, whereby reciprocation of the shaft does not at any time cause the inner screw night to pass beyond the sample inlet end of the tube.

9. A sampling device of the character described comprising a sampling tube adapted to be mounted with one end extending into the material to be sampled, a shaft mounted for rotation and for reciprocating movement within said tube, said shaft being Iprovided with an outer helical screw night disposed on the shaft adjacent the inlet end of the sampling tube and with an inner helical screw night of opposite pitch to said outer screw night disposed on the shaft adjoining said outer flight and extending toward the inner end of the sampling tube, a coupling collar secured to said shaft and provided with a peripheral cam groove extending completely therearound, the path of saidV cam groove lying in a plane disposed at an angle other than perpendicular to the longitudinal axis of the shaft, anxed collar surrounding said coupling collar and provided with a cam follower protruding from its inner surface into said cam groove, and means for rotating the shaft in the direction to cause the inner helical screw night to move material toward the discharge end of the sampling tube, whereby said shaft is simultaneously caused to move back and forth along its longitudinal axis.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date '751,340 Raht Feb. 2, 1904 1,170,842 Newhouse Feb. 8,. 1916 1,860,107 Lien May 24, 1932 1,862,250 Anderson June 7, 1932