US 3845788 A
Disclosed herein is a motor driven needle valve, with a manual override arrangement, for controllably feeding a stream of massecuite into a continuous centrifugal separator.
Claims available in
Description (OCR text may contain errors)
United States Patent 1191 Laven Nov. 5, 1974 l l MOTOR CONTROLLED VALVE FOR CONTINUOUSLY FEEDING VISCOUS  References Cited LlQUlDS UNITED STATES PATENTS Inventor: Thomas Laven, Hamilton, OhiQ 1,966,209 7/1934 Miller 251/130  Assignee: The Western States Machine Company Hamilton Primary Examiner-Robert NIISOI] Attorney, Agent, or Firm Albert C. Johnston  Filed: Oct. 3, 1973 pp 403,071 57 ABSTRACT Disclosed herein is a motor driven needle valve, with a  US. Cl 137/604, 251/122, 251/130, manual override arrangement, for controllably feeding 251/134 a stream of massecuite into a continuous centrifugal  lnt. Cl. Fl6k 19/00 separator.
5 8] Field of Search 137/604, 605, 25 Mia/112326 8 Claims, 3 Drawing Figures MQTOR CONTROLLED VALVE FOR CONTINUOUSLY FEEDING VISCOUS LIQUIDS In general, the present invention is directed broadly to continuous centrifuges of the type commonly employed for separating liquid and solid components of a viscous mixture such as massecuite. More particularly, the present invention relates to a new and improved needle valve apparatus for directing a stream of viscous liquid material into the basket of a continuously rotating centrifugal machine such as is in common use by the sugar refining industry for the separation of mother liquor and wash liquid from sugar crystals. Representative systems and apparatus for controllably and continuously delivering massecuite to centrifugal separators are shown and described in US. Pat. Nos. 3,223,283 and 3,393,805.
As discussed at length in the aforementioned patents, it is highly important to the efficiency of the separating operation that the massecuite be delivered into the rotating basket of the centrifuge at a substantially constant rate and in a uniform freely pouring stream. In other words, the pouring massecuite stream must be maintained as free from variation as possible. Accordingly, in these and other earlier feeding systems for controlling the flow of massecuite, efforts have been made to improve the control of and the characteristics of the massecuite stream which is delivered into the continuously rotating centrifugal basket. It is to such improvements that the present invention is specifically directed.
More particularly, in accordance with the present invention, a new and improved motor driven control valve having a manual override control element is provided, whereby the size of the valve opening formed at a circular outlet orifice and thus the size or flow rate of a stream of massecuite or like material pouring by gravity from the orifice is precisely determined by the positioning of a conical surface of a generally teardrop shaped needle that is movable axially relative to the orifice. The needle is supported on a stem which is displaceable axially by the rotation of a lead screw through a suitable drive transmission, such as a worm gear unit, driven by electric, pneumatic or hydraulic motor means in response to an appropriate control signal, for example, by a signal automatically generated by a servo control of known nature associated with the power supply circuit of the basket drive motor, and the valve stem is also displaceable axially relative to the lead screw by the manual operation of a handwheel associated therewith, so that the valve orifice can be closed or opened, or the size of the opening varied, independently of the motor.
The new valve may be mounted with its outlet orifice located at or even below the plane of the top rim of the continuously rotated centrifugal basket. Thus, the stream of massecuite falls only a short distance and is subjected to but minimal extraneous influences as it flows from the valve orifice to the desired point of delivery in the basket.
Further in accordance with the invention, the supporting means for the valve stem includes provisions for the introduction of a fluid treatment medium, such as water, steam or syrup, into the center of the massecuite stream flowing toward and from the outlet orifice of the valve. The treatment fluid enters the valve through a radial port communicating via a manifold with axially disposed conduits which deliver the fluid about the needle stem upstream of the orifice. As will be understood, the treatment fluid will be mixed with the viscous massecuite passing through the valve structure and into the centrifugal basket.
The new valve provides simple, efficient, and reliable control for the feeding of a free flowing massecuite stream. The foregoing and other features and advantages of the present invention will become apparent from the following detailed description of a preferred embodiment thereof taken in conjunction with the accompanying illustrative drawings, in which:
FIG. 1 is a front elevational view of a valve embodying the principles of the present invention, which valve is mounted immediately above the centrifugal basket of a centrifugal extractor (shown in cross section);
FIG. 2 is a vertical, cross-sectional view of the new valve of the present invention taken along line 2-2 of FIG. 1, and
FIG. 3 is an enlarged horizontal, cross-sectional view of the new valve taken through line 33 of FIG. 2.
Referring now to FIG. 1, a new and improved motor driven variable feed valve 10 with a discharge orifice 20 is mounted in the plane of the upper rim of a perforated conical basket 11, which is mounted on shaft 12 for rotation about a vertical axis. The shaft 12 is driven by belts 13 in known fashion to rotate the basket 11 at high speed for the centrifugal separation of the components of the charge material, typically sugar massecuite, fed therein through the valve 10.
In accordance with the invention, the discharge outlet 20 of the new and improved valve structure 10 is selectively controllable between a fully open position and a closed position. In the fully open position, a conical needle 31, mounted on a longitudinal stem 35, is substantially fully retracted within the valve body to define an annular gap between the conical surface of the needle 31 and the circular opening 32 of an orifice plate 33 mounted at the lower end of the valve body 34. In the closed position shown in FIG. 2, the needle 31 is seated in contact with the circular opening 32, eliminating any annular gap therebetween, and thereby completely closing the discharge outlet 20 to stop flow therethrough.
As an important aspect of the invention, controlled selective displacement of the needle 31 with respect to the opening 32 in the orifice plate 33 is effected by the translation of the stem 35 by a motor driven lead screw 36 threadingly engaged with the internal thread 23 of a drive nut 37 carried by a manually operable control element in the form of a handwheel 38. The nut 37 is fastened to the hub 39 of the handwheel by exterior thread 22. As shown in FIG. 2, the handwheel 38 is fixedly attached through the hub 39 and set screw 40 to the upper end of the needle stem 35, and may be used to position the valve stem 35, with respect to the orifice, independently of the operation of the motor drive for the lead screw 36.
As a further aspect of the invention, the upper portions of the needle stem 35 are supported in a bore 46 formed in the body 34 opposite the orifice 32, while the lower portions of the needle stem 35 are supported centrally of the valve body 34 within a bore 41 formed in a central supporting hub 42. The hub 42 is itself supported inwardly of the vertical, cylindrical side walls of the valve body 34 by the three radially inwardly extending arms 43, as shown in FIGS. 2 and 3. More specifically and as illustrated in FIG. 2, the valve body 34 is generally of inverted J-shape having a horizontal, cylindrical inlet portion 34a connected to the vertical, generally cylindrical portion of the valve body 34b by a 90 elbow portion 340. A flange 55 is formed at the inlet 34a for connection of the valve to a massecuite supply line (not shown). The upper portions of the needle stem 35 project through the valve body and are supported by a guide bushing 44 which is threaded into a boss 45 integrally formed in the elbow portion 34c, and by the bore 46 formed adjacent the boss. In accordance with the invention, the needle stem 35 is normally prohibited from rotation by the guide bushing and by the friction of packing ring elements 47 disposed about the needle stem within the boss cavity 48. Thus, rotation of the lead screw 36 will cause the translation of the nut 37 therealong, together with the stem 35 to vary the size of the discharge outlet 20.
As shown in FIG. 1, two vertical mounting plates 50, 51 are bolted to bosses 54 formed integrally with the valve body 34, which plates 50, 51 extend upwardly and parallel to the lead screw 36. A horizontal motor platform 52 mounting an electric motor 53, or other suitable drive such as a pneumatic or hydraulic motor, is supported between the plates 50, 51, as shown. A gear box 64 is mounted immediately beneath the motor 53, as shown in FIG. 2, which gear box supports and encloses the outer race of a ball bearing 55. The inner race of bearing 55 is fixed to the reduced diameter lead screw drive shaft 57 to which a worm wheel 58 is also fixedly mounted. A nut 59 threaded on the outer end of the shaft 57 urges the wheel 58 against the inner race of bearing 55 through a spacer 60. The worm wheel 58 is driven by a worm 59 supported on a shaft 66 journaled in the gear box on an axis perpendicular to the axis of the lead screw 36. The worm wheel is rotated by a sprocket wheel 67 carried on one end of the support shaft 66, which sprocket is driven by a roller chain 61 which transmits the drive of a bidirectional motor 53 thereto, in known fashion, through a sprocket 68. As indicated in FIG. I, the chain is covered by a suitable chain guard 62.
As will be understood and in accordance with the principles of the invention, the rotation of the lead screw 36 causes the needle stem 35 to be translated upwardly or downwardly (depending upon the direction of rotation thereof) through the threaded nut 37. The precise setting of the valve orifice may be effected through the controlled operation of the motor 53. More specifically, the amount of massecuite to be delivered at any instant through the valve 10 is remotely controlled through a servo control system which selectively energizes the motor 53. For safety purposes, the motor 53 will be automatically stopped at either of the extreme limit positions of the valve stem assembly (needle 31 seated in plate 33 or drive nut 37 adjacent gear box 64) by a limit switch 70 having switch arms 71 and 72 carefully positioned at points in the vertical path of the handwheel 38 corresponding to the desired limit positions. Accordingly, the limit switch 70 includes two sets of contacts which-are appropriately wired into the motor control circuitry in a manner to prevent energizing of the motor in a closing direction when the valve is completely closed, when the needle 31 is seated, and likewise to prevent energizing of the motor in an opening direction when the valve stem is at its upper limit of travel. Thus. when the handwheel 38 contacts either of the limit arms 71, 72, it will cause the motor to be automatically deenergized, thereby stopping further rotation of the stem 35.
In accordance with an important aspect of the present invention, it is possible to control the size of the valve opening 20, defined by the cooperation of the needle 31 and orifice 32, manually and independently of the electric motor 53. The lead screw 36 is restrained against rotation, relative to the drive nut 37, by the meshing of the worm wheel and worm. Accordingly, the needle stem may be translated with respect to the lead screw 36, by manually rotating the handwheel 38 and the nut 37 carried thereby. The manual rotation of the nut 37 through the handwheel 38 will, of course, selectively displace the needle stem 35 and the needle 31 carried thereby with respect to the orifice plate 33 in accordance with the direction of the rotation of the handwheel 38. Thus the handwheel 38 provides the valve 10 with capabilities of alternative or standby control as well as a direct manual override of the motor control.
In accordance with another important aspect of the present invention, a treatment fluid such as water or syrup or the like, may be introduced upstream of the orifice into the stream of viscous material flowing through the valve body 34. The treatment fluid is introduced through a port 80 formed in the hub 42. More specifically, as shown in FIGS. 2 and 3, the port 80 leads to a radial passage 81 extending through one of the arms 43 to an annular manifold 82 which communicates with eight axially extending conduits 83 which are arranged in the hub 42 concentrically about the needle stem 35, as shown best in FIG. 3. As will be understood, water or other treatment fluid introduced through the port 80 will flow by gravity along the outer walls of the lower portions of the stem and about the needle 31 mixing with the massecuite or other viscous fluid flow- I ing through the valve body 34. Additionally, the valve body is provided with a steam port for the introduction of steam or other treatment media into the flowing stream of viscous material, should it be desired or necessary. Enlarged openings 93, sealed by plates 94, are also included in the valve body upstream of the hub 42.
As shown in FIG. 1, the valve 10 is bolted through a horizontal plate 89 directly to an external top member 91 or the stationary curb structure 92 of the centrifugal separator. Advantageously, the discharge outlet 20, the size of which, of course, controls the massecuite stream as it flows freely under the influence of gravity into the centrifugal basket, is located as close to the basket 11 as possible, namely, the horizontal plane of the uppermost edge 11a of the rotating basket 11, as shown in FIG. 1. This location of the outlet orifice in the immediate proximity of the rotating basket 11 minimizes the time lag between changes in the flow of massecuite at the flow control point, i.e., the outlet 20, and avoids changes in the flow conditions at the delivery point of the massecuite within the basket. Moreover, the loca tion of the flow restricting orifice 20 at the final point in the massecuite supply to the centrifugal machine eliminates any possible interference with or distortion of the flow of massecuite by elbows, conducting tubes,
or the like, as is the case, for example, where the control valve (such as a gate valve) is located upstream of a massecuite discharge spout disposed above a centrifugal basket.
While the principles of the present invention and particulars of a preferred way of carrying it into practice have been described hereinabove and illustrated in the accompanying drawings, it will be evident that numerous variations and substitutions may be made by those skilled in the art without departing from the substance or contribution of the invention, which is intended to be defined by the appended claims.
What is claimed is:
l. A valve for controlling the delivery of a stream of viscous material, comprising:
an elongated valve body having an inlet at one end and a circular outlet orifice at the other end;
a conical needle means supported on an elongated valve stem means, said needle means being disposed in said orifice and movable axially relative thereto to close the orifice or to define an annular gap for outflow of a stream of said viscous material;
threaded drive nut means fixedly associated with said valve stem means; rotatable lead screw means in threaded engagement with said drive nut means; drive transmission means for rotating said lead screw means to move said valve stem means axially of said valve body; and maually operable means for rotating said drive nut means relative to said lead screw means independently of said transmission means. 2. A valve according to claim 1, further characterized in that said manually operable means comprises a handwheel fixed to said drive nut means. 3. A valve according to claim 1, further characterized in that said transmission means includes a worm wheel fixed to said lead screw means anda worm meshing with said worm wheel.
4. A valve according to claim "1, in which said valve body is a generally cylindrical hollow body having an opening defined in a portion thereof remote from said orifice;
said valve stem means extending axially through the space of said valve body and being supported in said opening; and
hub means disposed centrally in the space of said valve body and supporting said stem means therein.
5. A valve according to claim 4, in which said hub means is fixed rigidly to said valve body by at least one arm extending between said body and said hub means.
6. A valve according to claim 5, in which said hub means has a manifold formed therein;
a passage is formed in at least one said arm for conducting fluid into said manifold; and
conduit means extend from said manifold between said hub means and said valve stem means for delivering said fluid along said valve stem means to ward said needle means.
7. A valve according to claim 4, in which said opening has packing means disposed therein and means pressing said packing means in frictional engagement with said valve stem means, whereby the latter normally is restrained from rotation.
8. A valve according to claim 1, including limit means engageable by a member moved axially with said stem means at predetermined limits of a range of movement of said needle means to inactivate a motor acting through said drive transmission means to rotate said lead screw means.