US 3612276 A
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States ate  Inventor Thomas William Lowe Needham, Mass.
 Appl. No. 820,261
 Filed Apr. 29, 1969  Patented Oct. 12, 1971  Assignee Bird Machine Company South Walpole, Mass.
 VORTEX-TYPE SEPARATOR APPARATUS 5 Claims, 1 Drawing Fig.
 U.S.Cl 209/211  llnt. Cl 1804c 5/081, B04c 5/14  Field of Search 209/211, 496; 210/512  Reiierences Cited UNITED STATES PATENTS 1,686,435 10/1928 Chance 209/496 2,377,524 6/1945 Samson et a1 209/211 X 3,501,001 3/1970 Mulleret a1. 210/512X FOREIGN PATENTS 516,806 1/1940 England 209/211 Primary Examiner-Frank W. Lutter Assistant Examiner-William Cuchlinski, Jr. Att0rney--Edgar I-I. Kent ABSTRACT: A vortex separator is provided which is substantially more efficient than prior separators in cleaning fiber slurry at concentrations of 3 percent and above of impurities which will pass a 14-inch hole screen, the separator and its connections to a sump having specified design parameters and features some of which are critical for obtaining such efficiency and others of which are preferred for maximizing it.
VORTEX-TYPE SEPARATOR APPARATUS This invention relates to hydrocyclone or vortex-type separators for cleaning fiber slurry of impurities up to a size which will pass a it-inch hole screen, particularly at slurry concentrations of 3 percent and above.
lmpurities of the size range involved are commonly present in large quantities for example in waste paper slurry after it has been coarse-cleaned either in the pulper or by coarse screens or other coarse cleaners following the pulper to remove large objects such as tramp iron which will not pass a %-inch hole screen. The remaining impurities include as well as dirt a large amount of metal most usually in the form of staples and bits of paper which are held together by staples and are called in the trade puffed wheat. If such impurities are retained in substantial amount in the slurry as it goes to refiners which normally follow pulping, serious problems are encountered not only of wear and breakage of the refining equipment but also in that bits of the metal may escape the refiner and subsequent fine cleaning to cause defects in the l-leretofore, fiber slurries of dilute concentration such as l to 2 percent solids have been effectively cleaned of these remaining impurities by means of large size vortex separators, 12-inch diameter or larger, equipped with sumps to which the separated impurities are discharged. But at the higher concentrations of 3 to 6 percent or more which are increasingly utilized in mills it was found that these same separatorswere seriously deficient. In an effort to increase their efficiency on concentrated slurry such separators have been equipped with impellers operating at high speed in the vortex theoretically to increase velocity, energy, centrifugal force and separation; however, the increase in separation efficiency has not been satisfactory and the additional rotating equipment is expensive to build and operate.
The object of this invention is to provide a separator of the vortex type which is capable of cleaning high-density slurries of impurities of the specified size range much more effectively than prior cleaners without the use of additional vortex accelerating equipment.
I have discovered that the foregoing object can be attained with separators having a maximum diameter (herein referred to as D") in the range 4% inches to 10 inches provided the slurry feed rate is such as to maintain a pressure drop of at least of the order of 13 p.s.i. for slurry consistency of about 3 percent and higher for greater consistencies (attainable at usual available pressures of 20 to 30 p.s.i. or higher) and provided all the following critical design factors of the separator are observed:
1. The separator has a substantially nonconvergent (usually cylindrical) inlet end which joins a convergent section of frustoconical shape terminating in an apex outlet for separated impurities and has at the opposite inlet end a vortex finder through which accepted stock of the reversed inner vortex is discharged.
2. The apex outlet of the convergent section is connected to s sump, and a connection is provided for supplying elutriation water to the separated impurity fraction adjacent the outlet and before it reaches the sump.
3. The slurry inlet is tangential, feeding below a scroll which guides the first turn of the helically moving slurry below the inlet and has an area equivalent diameter (area equivalent to that of a circle having a diameter) in the range 1 inch to 0.5 D.
4. The included angle of the convergent conical section is in the range 6' to 12 and the total axial length of the nonconvergent and convergent sections from the portion of the slurry inlet furthest from the larger end of the convergent section is in the range D to 7.5 D.
5. The vortex finder inlet is located axially beyond the bottom of the inlet to the separator by a distance in the range 0.5 D to 1.25 D, it is spaced from the convergent section by a distance of at least 0.25 D and it has an inlet area equivalent diameter in the range 1.5 inches to 0.75 D.
6. The apex outlet has an area equivalent diameter in the range of which the maximum is 0.6 D and the minimum is 1.5 inches for cone angles of 8 and above and for smaller cone angles the larger of an area equivalent diameter of 1.5 inches or the area equivalent diameter of the outlet of a convergent section of the included angle less than 8 and having the maximum length permitted by other limitations set forth above, namely, (6.75 D)-l inch (maximum combined length of nonconvergent and convergent sections of 7.5 D under paragraph 4 above less the minimum length of nonconvergent section required by paragraphs 5 and 3 above of 0.5 D plus 0.25 D plus 1 inch or 7.50(0.5 D+0.25 D+l )=(6.75 D-l In addition to observing all the above-stated critical design factors, in preferred embodiments the apex outlet is connected to the pump by a tube having an area equivalent diameter at least substantially equal to that of the outlet, having a length of l to 3 D and being equipped with a tangential elutriation water feed. In preferred embodiments also D is about 5-7 inches; the axial length of the nonconvergent section from the top of the slurry inlet is about 3 D; the axial length of the convergent action is about 3 D to 3.5 D; the cone angle is about 8; the slurry inley has an area equivalent diameter of about 0.3 D to 0.45 D; and the vortex finder has a substantially circular inlet of a diameter about 0.5 D.
Separators according to the invention were extensively tested in a mill for efficiency in cleaning waste paper stock from a pulper dump chest of staples and puffed wheat. Comparison tests were also made with a lZ-inch diameter vortex separator having an impeller operating in the outer vortex.
In these tests, the numbers of staples and puffed wheat rejected and accepted in given time under like operative conditions were counted and the efiiciency of separation was determined as the percentage of the number rejected to the total number rejected and accepted. With a pressure drop of [3 p.s.i. and above the separator according to the invention and conforming to the preferred as well as the critical features at tained efficiencies of percent and. above at a slurry consistency of 3-4 percent. With a presure drop of 20 p.s.i. the efficiency was 94 percent. The l2-inch diameter separator was operated on the same slurry at pressure drop of 13 and above and also with elutriation in a tube between the apex outlet and the sump. With the impeller operating at approximate optimum speed of 3,600 rpm. the efiliciencies obtained were in the 60 to 70 percent range or below. With the impeller shut off there was no separation of puffedl wheat and the separation of staples was negligible.
In all tests with the separator according to the invention the amount of acceptable fibrous material rejected was small, well below an acceptable maximum. With higher consistency slurry, the results are comparable provided sufficient pressure drop is maintained, the minimum increasing about 2 p.s.i. with each 1 percent increase in consistency.
Tests were also run with separators according to the invention with various design parameters varied from the preferred ranges toward the outer limits of the critical ranges. The efficiencies obtained were not as good as with preferred embodiments but were better than the best efiiciencies consistently obtained with the l2-inch diameter unit.
The single FIGURE of the accompanying drawing shows a vortex separator according to the invention in a view partly in vertical section and partly in side elevation.
Referring to the drawing, the separator has a tubular body portion designated generally 10 formed of a cylindrical inlet end section 12 and a convergent frustoconical section 14 terminating in a circular apex outlet 16. An inlet i8 is provided at the outer end of the cylindrical section for connection to a source (not shown) of the aforedescribed slurry under the requisite pressure and has a rectangular inlet opening arranged to feed the stock tangentially into the separator under a scroll 20, which extends helically about the wall of section 112 sufficiently to insure that the first spiral turn of the incoming flow about the wall is guided below the inlet. A vortex finder 22 extends through the end of section 12 for connection at its outer end to piping (not shown) for removal of the accepted fraction and has a circular open inner end projecting below the inlet within section 12 as previously specified.
Outlet 16 is connected by a divergent frustoconical tube 24 and a gate valve 26 to the inlet 28 of a sump 30 shown as having a transparent wall 32 through which the contents may be observed. A gate valve 35 is provided at the bottom of sump 30. The operating levers 36, 38 of valves 26 and 34 respectively are connected by respective links 40, 42 to the pistons of fluid motors 44, 46 respectively which are supported by arms 48 and 50 respectively attached to the side of the valves. The operating connections to motors 44, 46 which are not shown may be arranged for hand operation or for automatic operation in a timed sequence.
A tangential inlet 52 is provided in tube 24 for connection to a source of water under pressure (not shown) for elutriation, preferably arranged as shown to direct the water opposite to the direction of spiral flow of the slurry along the wall section 14. An inlet 54 for connection to such source is also provided in sump inlet 28 to provide water for filling the sump after it is emptied and also preferably for dilution.
ln operation the slurry entering inlet 18 spirals about the wall of body 10, the impurities separating toward the wall under the shear and centrifugal forces developed. As the flow approaches outlet 16 the inner fraction separates to form an inner vortex containing accepted stock within and flowing in reverse direction to the outer vortex containing the impurities. The inner vortex is removed through vortex finger 22 as the accepted fraction while the outer vortex continues its vortical flow from outlet 16 through tube 24 where it receives elutriation water through inlet 52 preferably supplied at around 9 g.p.m. The function of elutriation at this point is to dilute the concentrated reject flow from outlet 16 in order to separate the solids thereof and to permit acceptable fibers or fibrous matter retained therein to escape with the elutriation water in reverse flow into the inner vortex without carrying impurities with it. This function is accomplished better by injecting the elutriation water into the reject stream counter to its direction of flow which also tends to slow down the flow, enabling better settling out of the rejected impurities in sump 30. Such settling is also facilitated by the addition of elutriation water at lower flows such as 3 g.p.m. throughinlet 54 in sump inlet 28, into which the rejected fraction flows through opened gate valve 26.
When the. rejected solids have accumulated sufficiently in sump 30 above closed gate valve 34, valve 26 is closed and valve 34 is opened, thereby emptying the sump. Valve 34 is then closed and sump 30 is preferably filled or nearly filled with water via inlet 54 before valve 26 is opened to repeat the cycle. In addition to its functions previously mentioned, the elutriation water through connection 52 aids in breaking up any mass of solids that may have accumulated above valve 26 while closed, thereby avoiding plugging. Avoidance of plugging and the elutriation function are also aided by making tube 24 divergent as shown, which is preferred.
The separator may be mounted in any convenient manner. As shown it is provided with mounting lugs 56 on the outer wall of section 12 for suspending the device from supporting structure with its axis generally vertical.
It will be understood that the parts and their interrelation conform to the design parameters specified above as critical because it has been determined that they are necessary for satisfactory perfonnance, and desirably also to the parameters specified above as preferable because it has been determined that better performance is thereby obtained. For convenience these parameters are recapitulated here in relation to the parts shown in the drawing:
The diameter D of section 12 is from 4.5 to inches, preferably 5-7 inches.
The combined axial lengths of sections 12 and 14 from the top of inlet 18 is 5 D to 7.5 D, preferably about 6 D, such length of section 12 being preferably about 3 D and of section 14 being preferably about 3 to 3.5 D;
The included cone angle of section 14 is from 6 to 12, preferably about 8.
Tangential inlet 18 has an area equivalent diameter of 1 inch to 0.5 D; preferably 0.3 D to 0.45 D;
Vortex finder 22 has its inlet spaced below the bottom of inlet 18 by a distance in the range 0.5 D to 1.25 D, has its inlet spaced from section 14 by a distance of at least 0.25 D and has an inlet with an area equivalent diameter in the range 1.5 inches to 0.75 D, being preferably circular with a diameter about 0.5 D;
Outlet 16 has an area equivalent diameter in the range 1.5 inches to 0.6 D, being preferably circular as shown;
Tube 24 preferably has an axial length of 1 to 3 D and is divergent as shown.
Manually operated leverage may of course be substituted for the fluid motor valve-operating connections shown or valve 26 may be dispensed with by substituting for valve 34 a reject removal system such as a helical conveyor extrusion system capable of removing the solids collected in sump 30 without dumping its liquid content continuously or intermittently.
In order to maintain the requisite pressure drop of about 13 psi. or more, it may be desirable to provide for adjustable recirculation of accepted stock to the slurry feed source.
l. Vortex-type separator apparatus capable of efficiently separating from high-density fibrous slurry impurities in a size range up to a size which will pass a -inch-hole screen at a maintained pressure drop at least of the order of 13 p.s.i., said apparatus comprising:
a tubular body formed of a substantially nonconvergent section joined to a convergent substantially frustoconical section having an included angle in the range 6 to 12, said body having a maximum diameter D in the range 4% to 10 inches;
an inlet for directing said slurry into said nonconvergent section adjacent the outer end thereof and tangentially along the wall thereof, said sectionbeing provided with a helical scroll for guiding said slurry below said inlet, said inlet having an area equivalent diameter in the range 1 inch to 0.5 D;
the combined axial lengths of said nonconvergent and convergent sections from the portion of the slurry inlet furthest from the larger end of said convergent section being in the range 5 D to 7.5 D;
a vortex finder for removing accepted slurry extending axially into said nonconvergent section, said vortex finder having an inlet spaced axially of said section from the bottom of said slurry inlet by a distance in the range 0.5 D to 1.25 D and from the larger end of said convergent section by a distance of at least 0.25 D and having an inlet area diameter equivalent in the range 1.5' inches to 0.75 D;
said convergent section having an outlet for a rejected slurry fraction containing such impurities at the smaller end thereof, said outlet having an area equivalent diameter in the range of which the maximum is 0.6 D and the minimum is 1.5 inches for cone angles of 8 and above and for cone angles less than 8 is the larger of (a) an area equivalent diameter of 1.5 inches or (b) the area equivalent diameter of the outlet of a convergent section having the included angle of less than 8 and a length of (6.75 D)-l inches;
a sump and connection means connecting said sump to said outlet;
means for discharging elutriation liquid into said rejected fraction adjacent said outlet and before said fraction reaches said sump;
means for discharging liquid into said sump, and means for removing from said sump at least periodically rejected impurities collected therein.
2. Separator apparatus according to claim 1 wherein said connection means includes a tube connecting said outlet to the inlet to said sump, said tube having an area equivalent 5. Separator apparatus according to claim 1 wherein D is about 5 to 7 inches, the axial length of said nonconvergent section from the portion of the slurry inlet furthest from the larger end of said convergent section is about 3 D, the axial length of said convergent section is about 3 D to 3.5 D and said included angle thereof is about 8, said slurry inlet has an area equivalent diameter of about 0.3 D to 0.45 D, and said vortex finder has a substantially circular inlet of a diameter about Patent No.
Inventor(s) C01. and the (SEAL) Attest:
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTEON Dated October 12, 1971 Thomas Hi1 l "I am Lowe sump is Signed It is certified that error appears in the above-identified patent and that said Letters Patent are ber t-,3; correcte as shown below:
line 59, change "s" to -a--.
line 16, change "pump" to --sump--.
after line 18, add --feed for elutr-iation also equipped f0rline 22, change "action" to -----section---.
line 23, change inley" to --inlet--.
line change "35" to --3 i--.
claim 5, line 9, after about, insert sealed this 25th day of April 1972.
OUZR GOTTSCHALK o on 1'- cf Patents (M POIOSD (104.9)