US3057665A - Pump - Google Patents

Description

A. A. ZALIS Oct. 9, 1962 PUMP 4 Sheets-Sheet 1 Filed June 24, 1960 ALBERT A. ZAL/S INVENTOR.

FIG. 3.

ATTORNEY A. A. ZALIS 3,057,665

PUMP

4 Sheets-Sheet 2 Oct. 9, 1962 Filed June 24, 1960 ALBERT A. ZALIS INVENTOR.

ATTORNEY Oct. 9, 1962 A. A. ZALIS 3,057,665

PUMP

Filed June 24, 1960 4 Sheets-Sheet 3 I TAT} [AmmumnmumDW/A FIG. 7.

W Ill mm- ALBERTA. ZALIS INVENTOR.

A T TOR/VEY A. A. ZALIS Oct. 9, 1962 PUMP 4 Sheets-Sheet 4 ALBERT A. ZALIS JZZWW l m EIIII ,I m mmmmmm ELM. I m mi I IIE Filed June 24, 1960 U States This invention relates to a pump and more particularly to apparatus arranged to produce a flow of fluid containing a high concentration of suspended solids of fibers by the interaction of a pair of mating screws.

It is common practice to use a two-screw pump where high-speed units are used for cases requiring constant, pulse-less flow of non-corrosive liquids having a wide range of viscosity. Such pumps are especially useful for heavy duty industrial and marine applications such as in supplying oil to burners, for transferring and unloading oil and similar fluid plastic materials. These pumps are capable of being designed with very simple construction of high quality materials with the result that they are extremely reliable for long-term, economical service, as Well as having a low initial cost. However, when one attempts to pump liquids containing high suspendedsolids concentrations and of very high viscosity, such as the pulp slurries which are encountered in paper mills, the screw pumps of the prior art are found to be deficient in many respects. Considerable difficulty is encountered with the material coming out of suspension, caking, and forming obstructions in the pump. Furthermore, such materials will not feed directly into the main pumping screws by gravity alone. Also, some of these suspended materials are likely to be abrasive in character and difficulty is experienced in maintaining seals. Furthermore, because of the non-homogeneous character of the fluid, the pump elements are presented with fluctuations in pumping force, thus producing axial force variations on the main shaft; this is troublesome in connection with bearing maintenance. Some of these pulp slurries and the like are corrosive to a certain extent and difficulty is experienced in maintaining the bearings and seals. These and other difficulties experienced with the'prior art devices have been obviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide a pump particularly adapted to use with very heavy slurries and fluids containing high concentrations of suspended material.

Another object of this invention is the provision of a screw type pump having a novel inlet construction which assists the feeding of high-density material into the pump.

A further object of the present invention is the provision of a twin screw pump having apparatus arranged to feed liquids containing a high concentration of solids into the main pumping screws despite its high concentration.

It is another object of the instant invention to provide a screw-type pump which is particularly adapted for use with high concentration of suspended solids and suspended abrasive solids which, nevertheless, is capable of a long life of useful service with a minimum of maintenance problem.

It is a further object of the invention to provide a screwtype pump having an inlet auxiliary screw arrangement for use with heavy slurries and high concentration suspended solids without loss of feed.

A still further object of this invention is the provision of a screw-type pump having a bearing construction particularly adapted for use with non-homogeneous materials where wide fluctuations of force on the main screws is encountered and to withstand both axial and thrust loadings imposed by the main screws.

atent O p 3,057,665 Patented Oct. 9, 1962 It is a still further object of the present invention to provide a pump of the screw type having means for being conveniently cleaned by steam and water.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to certain of its structural forms, as illustrated by the accompanying drawings in which:

FIG. 1 is a perspective view of a pump embodying the principles of the present invention;

FIG. 2 is a front elevation of the pump;

FIG. 3 is a rear elevation of the pump;

FIG. 4 is an end elevation of the pump;

FIG. 5 is another end elevational view of the pump;

FIG. 6 is a plan view of the invention;

FIG. 7 is a horizontal sectional view of the pump taken on the line VIIVII of FIG. 2; and

FIG. 8 is a vertical sectional view of the pump taken on the line VIII-VIII of FIG. 6.

Referring first to FIGS. 1 through 6, wherein are best shown the general features of the invention, it can be seen that the pump, designated generally by the reference numeral 10, consists of a body 11 having a front head 12 and a rear cover 13 attached, respectively, to a front bearing bracket 14 and a rear bearing bracket 15; these, in turn, are attached to the respective ends of the body 11. Split glands 16 (see FIG. 6) are associated with a long shaft 17 and a short shaft 18. The body 11 includes a main portion 19 of oval cross-sectional shape mounted on legs 21 and 22. At the end of the main portion 19 which is adjacent the rear bearing bracket 15 an inlet hopper 23 is formed, while at the other end of the main portion 19, which is adjacent the front bearing bracket 14, an outlet or discharge fitting 24 is formed. One side of the inlet hopper 23 is provided with an access door 25, while the other side is provided with another access door 26. It should be noted that all of the main elements of the pump are provided with flanges with which they are bolted to adjacent parts. For instance, the front bearing bracket 14 is provided with a flange at each end by which it may be bolted to the front head 12 and to one end of the body 11. In a similar manner, the rear bearing bracket 15 is provided with a flange at one end for bolting to the rear cover 13, while a similar flange is provided at its other end for bolting to the body 11. The discharge fitting 24 is provided with a suitable flange at its outer end for attachment to a conduit (not shown) leading to the apparatus in which the slurry or liquid is to be used. The inlet hopper 23 is provided at its upper edge with a broad flange 27 which is adapted to be bolted to an inlet conduit (not shown). It should also be noted that the major elements of the pump are provided with suitable strengthening ribs. For instance, between the end flanges of the front bearing bracket 14 strengthening ribs are cast. This is also true of the rear bearing bracket 15 which has suitable strengthening ribs extendingbetween its end flanges; similar ribs are provided on the legs 21 and 22. and on the discharge fitting 24, as Well as certain portions of the body 11, particularly around the inlet hopper 23.

Referring now to FIGS. 7 and 8, which best show the interior of the pump, the long shaft 17 is provided with a main pumping screw 28, while the short shaft 18 is provided with a similar main pumping screw 29. The screws 28 and 29 are formed for conjugate mating action and lie within a suitable bore 31 formed within the main portion 19 of the body 11. The construction and action of these screws is well known in the art and serves to create, when rotating, a pressure diflerence and a flow of material from the inlet hopper 23 to the outlet fitting 24. The main portion 19 of the body 11 is formed with a chamber 32 which underlies the hopper 23 and in this chamber the long shaft 17 is provided with a feed screw 33, while the short shaft 18 is provided with a similar feed screw 34. As is evident in FIG. 7, these screws are of very thin-walled construction and are provided with a fairly long lead. They do not touch, although their relationship is such that the portion of one which is adjacent the shaft of the other lies midway between two portions at which the latter screw approaches the shaft of the first-mentioned one; this guarantees that not only can there be no mating, but also that there be no interference between the two. The chamber 32 has approximately the same height as its dimension in the direction of the axes of the shafts; however, its width is approximately twice that of its heighth and axial length, as is evident from the drawings. Overlying this chamber is the interior chamber 35 of the inlet hopper 23. The chamber 35 has approximately the same width but is considerably larger than the horizontal cross-sectional area of the chamber 32 and is generally square in shape. As is evident in FIG. 8, the lengthwise dimension merges into the lengthwise dimension of the chamber 32 by the provision of a shelf 36 overlying the main body portion 19 containing the bore 31. Another shelf 37 arranged considerably higher in the hopper overlies the portion of the body 19 to which the rear bearing bracket is bolted. The side surfaces of the chamber and the chamber 32 are generally aligned, and the chamber 32 is tapered inwardly at its lower portion to roughly approximate the outer edges of the screws 33 and 34. The bottom of the chamber 32 is provided with a drain hole 38 which is normally closed by a plug 39.

The front head 12 is provided with a hollow interior 41 and apertures 42 and 43, 44 and 45, suitably normally closed by plugs, are provided on the tops, bottoms and both sides. Within this chamber the long shaft 17 is provided with a timing gear 46 which meshes with a similar timing gear 47 keyed to the short shaft 18. Also within the chamber 41 of the from head 12 is a roller bearing 48 mounted on the short shaft 18 and a roller bearing 49 mounted on the long shaft 17, in both cases the bearings being at the outboard end of the shafts relative to their timing gears. At the inboard side of the timing gear 46 and lying within the front bearing bracket 14 the long shaft 17 is provided with a roller bearing 51, while in a similar location the short shaft 18 is provided with a roller bearing 52. It can be seen, then, that the timing gears 46 and 47 are mounted between bearings and are separately lubricated through the apertures 42, 43 44 and 45. It can be seen that the long shaft 17 is provided with a threaded portion 53 on which a lock nut 54 is mounted and which engages and holds in place the inner race of the roller bearing 49. The short shaft 18 is similarly provided with a threaded portion 55 on which is threaded a lock nut 56 which engages and holds in place the inner race of the roller bearing 48. The adjacent end of the long shaft 17 is suitably formed for attachment to a drive motor (not shown). The opening in the front head 12 through which the long shaft 17 extends is provided with a suitable seal 57 to prevent access thereto of dirt and to prevent loss of lubricant from the chamber 41. A snap ring 58 engages a groove in the surface of the front head 12 on the side of the bearing 49 opposite the lock nut 54 and holds the outer race of the bearing in place within a counterbore provided therefor. A similar snap ring is provided for the bearing 48 and for the roller bearings 51 and 52 on the sides which face the timing gears 46 and 47. Furthermore, suitable annular spacer blocks are provided between the inner race of each of the bearings and its corresponding timing gear.

The front bearing bracket 14 is provided centrally with an opening 59 which extends vertically entirely therethrough and defines an inner wall 61 and an outer wall 62, both extending transversely of the pump. The inner wall 61 is provided with a bore 63 in which lies the bearing '51. Also located in this bore is a bushing 64, an oil labyrinth ring 65, and an oil seal 66. The outer wall 62 of the front bearing bracket is provided with a similar bore 67 through which the short shaft 18 passes and which carries the bearing 52 as well as a similar sealing assemblage to that described above in connection with the long shaft 17. The long shaft 17 is provided with a shaft sleeve 68 while the short shaft 18 is provided with similar shaft sleeve 69; around each of these sleeves is one of the split glands 16 suitably connected to an extension of the inner wall 61 of the front bearing bracket 14. Extending into the opening 59 from the inner wall 61 the front bearing bracket 14 is provided with an abutment 71 having two suitable bores for carrying the shafts 17 and 18 and it is with these bores that the split glands 16 are associated as well as with the shaft sleeves 68 and 69. Between the glands 16 and the inner part of the pump the bores in the abutment 71 are provided with packing rings 72 surrounding the shaft sleeves 68 and 69. Next to these packing rings the sleeve is surrounded with a Teflon lantern ring 73 having a Teflon packing ring on either side. Finally, each of the bores is closed by a stufiing box bushing 74. In the drawing it can be seen that each of the shaft sleeves 68 and 69 is provided with an enlarged head which lies within the main portion 19 of the body 11 and which is suitably threaded to the shaft on which it is mounted. Mounted on the long shaft 17 within the main portion 19 of the body 11 and lying between the shaft sleeve 68 and the main screw 28 is a discharge feeder 75 which is in the form of a paddle wheel suitably keyed to the shaft. The short shaft 18 which is closest to the discharge pipe 24 is not provided with such a feeder and the ends of the feeder blades come closely adjacent to the shaft at that point. The blades, incidentally, of the feeder 75 extend axially lengthwise from the end of the screw 28 to the inner wall 61 of the front bearing bracket 14. It should be noted throughout that the main screws 28 and 29 as well as the feed screws 33 and 34 are suitably keyed to their respective shafts. The discharge feeder 75 has its blades arranged in a generally helical fashion to form what might be termed a right hand screw as it will be observed when looking from the hopper 23 toward the protruding end of the long shaft 17.

At the other end of the pump it may be observed that the rear bearing bracket 15 is also provided with a vertical passage 76 extending therethrough and defining an outer wall 77 and an inner wall 78 which is immediately adjacent the body 11. From the wall 78 extends an abutment 79 having bores to receive the shafts and being provided with sealing means similar to those associated with the bores in the abutment 71. As can be observed in this view, the split gland 16 associated with the long shaft 17 is provided with a swing bolt 81 which is pivoted to the abutment 79 by means of an eye formed in the bolt and surrounding a suitable cap screw 82. Each gland is provided with an upper and a lower swing bolt for bringing the gland into engagement with the seal and sleeve arrangement lying Within the abutment 79. The outer wall 77 of the rear bearing bracket 15 is provided with a counterbore 83 opening away from the main part of the pump and in this counterbore is located a double tapered roller bearing 84, this being a bearing particularly adapted to receive axial loads as well as radial loads. At its inner side a suitable seal 85 prevents the entrance of dirt to and the escape of lubricant from the passage 76, while at the other side on the extreme end of the shaft 17 a lock nut 86 is provided. The short shaft 18 is provided with a similar taper roller bearing 87 and is also provided with suitable seal and lock nut. The rear cover 13 is provided with short recesses into which the ends of the shafts may extend. An aperture 88 enters the cover 13 and is normally closed by a plug 89, while similar apertures and plugs are applied in the upper and lower parts of the cover to permit lubrication and drainage.

A steam jet opening 91, normally closed by a plug, extends through the wall of the hopper 23 in the upper portion thereof. The lantern rings which are provided in connection with each of the abutments 71 and 79 are shown as having an H-shaped cross-section and the walls of the abutments are provided with normally-plugged apertures for flushing the lantern rings and packing; each lantern ring is provided on either side with a special Teflon packing ring. By continuous flushing with adequate pressures, the suspended material (which may be abrasive) is kept from entering the packings. The two main pumping screws are provided with a special profile which is well known in the art and which is particularly adapted to prevent trapping of the stock as it moves through the pump.

The operation of the invention will now be readily understood in vie-w of the above description. The material to be pumped, which in this case is a high-viscosity or high-density fluid or a fluid containing a high concentration of suspended solids, such as paper pulp, enters the pump through the inlet hopper 23. The fluid lies for a while in the chamber 35 of the hopper which is very large and has abroad horizontal cross section. From this large chamber the material flows by gravity at a high velocity into the chamber 32 which is considerably smaller. This it does by liquid falling over the edge of the shelves 36 and 37 as well as falling directly downwardly onto the feed screws 33 and 34. The long shaft 17 is driven by the exterior drive motor (not shown) and drives the short shaft through the timing gears 46 and 47. As is normal in such pumps, the shafts run in opposite directions. The feed screws 33 and 34 lying almost entirely along the length of the chamber 32 force the material, despite it lack of fluidity, toward the main screws 28 and 29. These screws lie well within the bore 31 in the main portion 19 of the body 11. Although the high concentration of solids in this fluid tends to inhibit its flow into the feed screws, once it has arrived at the feed screws this characteristic is of assistance in forcing the fluid toward the main screws. These screws also have the effect of breaking up any agglomeration of solids which may be present in the fluid because of its lack of homogeneity and, of course, it overcomes difficulties due to entrapped pockets of air in the fluid. Large particles of wood or chemical masses of suspended material are easily forced into the screws by the feed screws 33 and 34. When the fluid reaches the main pumping screws 28 and 29, these screws act in their normal way to force the material out through the discharge fitting 24. However, again, because of the high density characteristic of this fluid, it is possible that plugging and dead areas may occur in the discharge areas of the screws within the main portion 19 and, for this purpose, the discharge feeder 75 rotates to clean this outlet chamber of material. Since the movement of the discharge material from the pump is at a right angle to the main axis of the screws, it can be seen that in the case of a heavy slurry and high concentrations some difliculty might be encountered, but the discharge feeder 75 takes care of this problem and expels the material at right angles to the shaft axis. Because of the non-homogeneous characteristic of the material being pumped, one of the problems encountered is that of bearing failure due to heavy axial or thrust loading. The bearing 87 takes care of this problem very effectively since it is a tapered roller bearing capable of thrust loads as well as radial loads. It should be noted that the pumping cavities are isolated from the bearings by means of the relatively complex sealing or packing members contained within the abutments 71 and 79 of the front bearing bracket 14 and the rear bearing bracket 15, respectively. The bearing 87 is at the outer end of the shaft 17 and the bearings 49 and 51 are exterior at the other end of the shaft, In this connection it is also interesting to note that the timing gears 46 and 47 are located between two sets of roller bearings, thus obviating any problem of gear mis-alignment and wear. It should be noted that throughout the pump it is provided with means for cleaning the seals and lubricating the bearings. Furthermore, all of the cavities which might give difliculty are provided with handholes or steam cleaning apertures. The glands 16 in every case are readily accessible through the vertical passages in the bearing brackets 14 and 15.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent is:

l. A screw pump for fluids containing a high concentration of suspended solids, comprising an elongated body, two shafts extending through the body, means connecting the shafts for rotation in opposite directions, a pumping screw associated with each shaft, an inlet hopper overlying the body at a position removed from one end of the pumping screws, a discharge fitting extending from the body at the other end of the pumping screws, a feed screw associated with each shaft and underlying the hopper, the feed screws being formed to transfer the fluid from the hopper to the said one end of the pumping screws, a bearing bracket attached to each end of the body and having a vertical wall substantially spaced from the body, bearings mounted in the wall constituting substantially the sole support for the shafts, and a stufling box surrounding each shaft at the position it emerges from the body, and a passage entirely through each bracket for exposing a portion of each shaft adjacent each stuffing box and permitting adjustment of the stufflng box.

2. A screw pump as recited in claim 1 wherein one bearing of each shaft is capable of carrying substantial axial loading.

3. A screw pump for high density fluids, comprising an elongated body, two shafts extending through the body, means connecting the shafts for rotation in opposite directions, a pumping screw associated with each shaft, an inlet hopper having a large rectilinear cross-sectional area overlying the body at a position removed from one end of the pumping screws, a discharge fitting extending from the body at the other end of the pumping screws, a feed screw associated with each shaft and underlying the hopper, the feed screws being formed to transfer the fluid from the hopper to the said one end of the pumping screws, the feed screws lying in a chamber formed in the body and opening upwardly into the hopper, the chamher having a rectilinear cross-sectional area substantially less than that of the hopper, a bearing bracket attached to each end of the body and having a vertical Wall substantially spaced from the body, bearings mounted in the wall constituting substantially the sole support for the shafts, a stufling box surrounding each shaft in the position at which it emerges from the body, and a passage extending entirely through each bracket for exposing a portion of each shaft adjacent each stutfing box and for permitting adjustment of the stufling box.

4. A screw pump for fluids containing a high concentration of suspended solids, comprising an elongated body, two shafts extending through the body, means connecting the shafts fo rotation in opposite direction, a pumping screw associated with each shaft, an inlet hopper overlying the body at a position removed from one end of the pumping screws, a discharge fitting extending from the body at the other end of the pumping screws, a feed screw associated with each shaft and underlying the hopper, the feed screws rotating without contact with one another to transfer the fluid from the hopper to the said one end of the pumping screws, the feed screws having threads of relatively small wall thickness and having relatively long leads, a bearing bracket attached to each end of the body and having a vertical wall substantially spaced from the body, bearings mounted in the wall constituting substantially the sole support for the shafts, a stuffing box surrounding each shaft in the posit-ion at which it emerges from the body, and a passage entirely through each bracket for exposing a portion of each shaft adjacent each stuffing box and for permitting adjustment of the stuffing box.

5. A screw pump for high density fluids, comprising an elongated body, two shafts extending through the body, means connecting the shafts for rotation in opposite directions, a pumping screw associated with each shaft, an inlet hopper overlying the body at a position removed from one end of the pumping screws, a discharge fitting extending from the body at the other end of the pumping screws, a feed screw associated with each shaft and underlying the hopper, the feed screws rotating without contact with one another to transfer the fluid from the hopper to the said one end of the pumping screws, the feed screws having threads of relatively small wall thickness and having load leads, the feed screws lying in a chamber formed in the body and opening upwardly into the hopper, the chamber having a rectilinear cross-sectional area substantially less than that of the hopper, a bearing bracket attached to each end of the body and having a vertical wall substantially spaced from the body, bearings mounted in the wall constituting substantially the sole support for the shafts, a stufling box surrounding each shaft in the position at which it emerges from the body, and a passage extending entirely through each bracket for exposing a portion of each shaft adjacent each stufling box and for permitting adjustment of the stuffing box.

6. A screw pump for high density fluids, comprising an elongated body, two shafts extending through the body, means connecting the shafts for rotation in opposite directions, a pumping screw associated with each shaft, an inlet hopper overlying the body at a position removed from one end of the pumping screws, a discharge fitting extending from the body at the other end of the pumping screws, and a feed screw associated with each shaft and underlying the hopper, the feed screws rotating without contact with one another to transfer the fluid from the hopper to the said one end of the pumping screws, the feed screws having threads of relatively small wall thickness and having long leads, the feed screws lying in a chamber formed in the body and opening upwardly into the hopper, the chamber having a rectilinear cross-sectional area substantially less than that of the hopper, horizontal shelves at the junction between the chamber and the hopper, a bearing bracket attached to each end of the body and having a vertical wall substantially spaced from the body, bearings mounted in the wall constituting substantially the sole support'for the shafts, a stuffing box surrounding each shaft in the position at which it emerges from the body, and a passage extending entirely through each bracket for exposing a portion of each shaft adjacent each stufling box and for permitting adjustment of the stutfing box, one bearing of each shaft being capable of carrying substantial axial loading.

7. A screw pump for fluids containing high concentration of suspended solids, comprising an elongated body, two shafts extending through the body, means connecting the shafts for rotation in opposite directions, a pumping screw associated with each shaft, an inlet hopper having a large rectangular cross-sectional area overlying the body at a position removed from one end of the pumping screws, a discharge fitting extending from the body at the other end of the pumping screws, a discharge feeder in the form of a set of vanes mounted on one of the shafts adjacent the discharge fitting to transfer the fluid from the said other end of the pumping screws to the discharge fitting, and a feed screw associated with each shaft and underlying the hopper, the feed screws rotating without contact with one another to transfer the fluid from the hopper to the said one end of the pumping screws, the feed screws having threads of relatively small wall thickness and having long leads, the feed screws lying in a chamber formed in the body and opening upwardly into the hopper, the chamber having a rectilinear cross-sectional area substantially less than that of the hopper, horizontal shelves at the junction between the chamber and the hopper, a bearing bracket attached to each end of the body and having a vertical wall substantially spaced from the body, bearings mounted in the wall constituting substantially the sole support for the shafts, a stutling box surrounding each shaft in the position at which it emerges from the body, and a passage extending entirely through each bracket for exposing a portion of each shaft adjacent each stufling box and for permitting adjustment of the stuffing box, one bearing of each shaft being capable of carrying substantial axial loading.

References Cited in the file of this patent UNITED STATES PATENTS 1,751,703 Long Mar. 25, 1930 1,762,708 Allred June 10, 1930 2,231,357 Burghauser Feb. 11, 1941 2,640,430 Sennett June 2, 1953 2,705,922 Rathman Apr. 12, 1955 2,745,643 Kleinlein May 15, 1956 2,908,226 Rich Oct. 13, 1959 2,939,745 Carlsmith June 7, 1960

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