Abstract:
A multi-way valve suitable for use with large particle abrasive slurries. The valve has a housing and a seat piece affixed to the housing that defines a chamber. The seat piece has a conical valve seat. A rotor defines a conical base end that is received in the conical valve seat. A spring member biases the conical base end of the rotor against the conical valve seat to center the rotor and to allow the rotor to glide over large particles and for compensating for wear of the rotor over the lifetime of said rotor. The rotor has a first fluid path that is over a top of the rotor and a second fluid path that is through a bridge passageway in the rotor, thereby pressure balancing said rotor. The first fluid path provides continual flushing of particles from the chamber.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to valves for use in the conveyance and directional control of abrasives-laden fluids, and more particularly to valve elements for use in contamination prone environments such as those found in construction, mining, or mineral processing equipment and laboratory instruments. 
       BACKGROUND OF THE INVENTION 
       [0002]    Valves are designed to selectively seal one port from another. High pressure valves are typically designed with very small clearances and fine sealing surfaces. When used with abrasive slurries, highly polished surfaces of high pressure valves are easily damaged by solids, causing the surfaces to no longer seal or resulting in mechanical binding of the rotating or sliding components. Subjecting a valve to abrasive solids presents difficulties since abrasive solids tend to grind away at valve bearings and sealing surfaces causing then to fail by leaking or mechanical binding. Generally, smaller valves can only tolerate small particles. 
         [0003]    Because of the wear issues, difficulties were encountered when attempting to locate a suitable four-way valve for directional control of slurries. Several common valves were considered for this purpose. Three-way ball valves were configured to make a four-way circuit. The ball valves were plumbed into a fluid test circuit and run less than 720 cycles before excessive torque caused them to fail. Disassembly and inspection of the components revealed that solids contamination of the bearings and rotating surfaces caused them to bind and fail. The bearings, shaft, and all sealing surfaces were damaged by the abrasive solids. A plunger type cone and seat design with an air actuator was also tested. This valve survived less than 12 cycles before failure. 
       SUMMARY OF THE INVENTION 
       [0004]    It is desirable to provide a valve suitable for use in high temperatures and pressure applications for four-way directional control of solids-laden slurries. The valve of the invention is designed to handle relatively large particle sizes while eliminating the problems commonly associated with abrasive solids. In addition, the valve can be constructed of temperature, corrosion and abrasion resistant materials for use in harsh environments. 
         [0005]    For some applications, a four-way directional control valve for applications involving corrosive, solids-laden slurries at high temperatures and pressures may be needed. In one example, the function of such a valve is to control flow direction of fluids from one accumulator to another when operated in a reciprocating manner. 
         [0006]    The slurry valve of the present invention includes a pressure housing having a cone shaped rotor that fits precisely into a conical four-port valve seat. Ports on the rotor align with ports on the valve seat to direct the flow path. The rotor may be actuated 90 degrees by a shaft or stem, causing a selected pair of ports to be in communication with one another. The ports may be designated A, B, C, and D. In position  1 , ports A-B and C-D are connected. In position  2 , ports A-D and B-C are connected. 
         [0007]    The rotor is spring loaded against the valve seat with sufficient force to effect a seal between adjacent ports. The rotor is constructed of an abrasion resistant material to resist wear. The rotor is also pressure balanced so that torque requirements and sealing forces are independent from system pressure changes. The spring loading of the rotor also allows the rotor to float over large particles without binding. The valve is constructed of high temperature, corrosion resistant materials for use in harsh environments. The design facilitates easy service and repair. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a cross-sectional side view of the HPHT four-way slurry valve of the invention. 
           [0009]      FIG. 2  is a cross-sectional bottom view of the valve of  FIG. 1 , taken along line  2 - 2  of  FIG. 1 . 
           [0010]      FIG. 3  is a bottom view of the valve of  FIG. 1  showing a schematic of the flow paths when the rotor is in position  1 . 
           [0011]      FIG. 4  is a bottom view of the valve of  FIG. 1  showing a schematic of the flow paths when the rotor is in position  2 . 
           [0012]      FIG. 5  is a perspective view of the conical base end of the rotor of the present invention. 
           [0013]      FIG. 6  is a perspective view of the stem end of the rotor of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0014]    Before explaining the present invention in detail, it is important to understand that the invention is not limited in its application to the details of the construction illustrated and the steps described herein. The invention is capable of other embodiments and of being practiced or carried out in a variety of ways. It is to be understood that the phraseology and terminology employed herein is for the purpose of description and not of limitation. 
         [0015]    Referring first to  FIG. 1 , shown is the four-way valve  10  of the invention. Valve  10  has a housing  20  having a base end  22  and a stem end  24 . Housing  20  defines a receptacle  25  in base end  22  and a longitudinal passageway that communicates stem end  24  with the receptacle. Bushing  26  is received within the longitudinal passageway proximate stem end  24  of housing  20 . 
         [0016]    A seat piece  30  ( FIGS. 1 ,  2 ) is received on base end  22  of housing  20 . Seat piece  30  has a base flange portion  32  and a central insertion portion  34 . Central insertion portion  34  is received within receptacle  25  of housing  20 . Central insertion portion  34  of seat piece  30  has a conical valve seat  35  ( FIG. 1 ), thereon. Valve seat  35  has a conical surface that defines four ports that lead to four longitudinal passageways, i.e., passageways  36 A,  36 B,  36 C, and  36 D. Base flange portion  32  defines radial passageways leading to exterior ports, i.e., radial passageway  38 A, radial passageway  38 B, radial passageway  38 C, and radial passageway  38 D. Seat piece  30  and housing  20  are bolted together with bolts  39  ( FIGS. 3 ,  4 ) to make up a pressure housing of valve  10 . Seat piece  30  and housing  20  are sealed with an elastomeric seal  40  ( FIG. 1 ). Seat piece  30  and housing  20  are constructed of materials having sufficient strength and other properties for the intended service. 
         [0017]    A stem  41  has a first diameter portion  42 , a flange  44 , and a second diameter portion  46 . First diameter portion  42  passes through the longitudinal passageway of housing  20  and through bushing  26 . Flange  44  is adjacent an interior wall of receptacle  25  of housing  20 . Second diameter portion  46  of stem  41  extends into receptacle  25 . Sealing members, such as O-rings  48 , surround stem  41  for forming a pressure seal between stem  41  and the longitudinal passageway of housing  20 . 
         [0018]    Radial support for stem  41  is provided by bushing  26 , and axial support is provided by thrust washer  49 . Thrust washer  49  provides two functions. First, thrust washer  49  provides axial support of stem  41  when hydraulic pressure and spring forces are applied. Thrust washer  49  also serves as a wiper or pre-seal to exclude particles from contaminating the running clearance between stem  41  and housing  20 . Thrust washer  49  also minimizes particle contamination of o-rings  48 . Thrust washer  49  is preferably constructed of an abrasion resistant polymer material with self-lubricating properties for low friction. 
         [0019]    Rotor  51  ( FIGS. 1 ,  5 ,  6 ) is located within the receptacle of housing  20 . In a preferred embodiment, a clearance  53  ( FIG. 1 ) is provided between an outer surface of rotor  51  and inside surface of housing  20 . Clearance  53  should be sufficiently larger than the maximum particle size for which the valve is designed to prevent potential bridging or binding of rotor  51 . Although the size of clearance  53  may differ in various applications, it is desirable for clearance  53  to be approximately four times the anticipated particle size. Rotor  51  is actuated by stem  41 . Torque applied to stem  41  is transmitted to rotor  51  via pin  57  which engages both parts. Rotor  51  has a conical base end  52  ( FIGS. 1 ,  5 ) for locating in conical seat  35  of seat piece  30 . Conical base end  52  of rotor  51  is shaped to mate precisely with the conical valve seat  35 . Rotor  51  has stem end  54  ( FIGS. 1 ,  6 ) that defines a stem receptacle for receiving an end of second diameter  46  of said stem  41 , as shown in  FIG. 1 . Pin  57  secures rotor  51  to stem  41  so that rotor  51  rotates with said stem  41 . As can best be seen in  FIGS. 5 and 6 , rotor  51  defines a first rotor passageway  55 A, a second rotor passageway  55 B, and a partial circumferential bridge passageway  56  formed in conical base end  52 . Partial circumferential bridge passageway  56  has first port end  56 C and a second port end  56 D. 
         [0020]    Referring back to  FIG. 1 , spring  60  surrounds said second diameter  46  of said stem  41 . Spring  60  is engaged with flange  44  of stem  41  on a first end and is engaged with stem end  54  of rotor  51  on a second end. Spring  60  applies a force to rotor  51  for facilitating tight engagement of conical base end  52  of rotor  51  against conical valve seat  35  of said seat piece  30 . Therefore, rotor  51  is axially loaded against valve seat  36  using spring  60  with sufficient force to affect a port-to-port seal. 
         [0021]    Stem  41  may be rotated for rotating rotor  51  for locating rotor  51  in a one of a first rotational position ( FIG. 3 ) or a second rotational position ( FIG. 4 ). When rotor  51  is positioned in the first rotational position, ports corresponding to radial passageways  38 A and  38 B are connected via partial circumferential bridge passageway  56  and ports corresponding to radial passageways  38 C and  38 D are connected via first rotor passageway  55 A ( FIGS. 1 ,  5 ,  6 ) and second rotor passageway  55 B ( FIGS. 5 ,  6 ). In the embodiment shown and discussed above, radial passageways  38 A-D are hydraulically connected in adjacent pairs to provide a four-way directional control circuit. Ports  56 C and  56 D of bridge passageway  56  are hydraulically connected across a face of conical base end  52  of rotor  51 . Rotor passageways  55 A and  55 B hydraulically connect a face of conical base end  52  through to the opposite side of rotor  51 . This hydraulic path provides pressure balancing of rotor  51  as well as a continuous flushing of particles from the valve housing  20  when in service. When rotor  51  is rotated 90 degrees to the second rotational position ( FIG. 4 ), radial passageways  38 A and  38 D are connected via partial circumferential bridge passageway  58  and radial passageways  38 B and  38 C are connected via first rotor passageway  55 A and second rotor passageway  55 B. 
         [0022]    In the present configuration, rotor  51  is designed to operate in two positions, 90 degrees apart. The present configuration provides a four-way direction control circuit. In position  1 , radial passageways  38 A-B and  38 C-D are hydraulically connected. In position  2 , radial passageways  38 A-D and  38 B-C are hydraulically connected. In the embodiment shown, two ports associated with radial passageways  38 A-D are slowly closing during rotation while the other two ports associated with radial passageways  38 A-D slowly open. This prevents pressure spikes during rotation. Radial alignment is provided by the mating of the two conical surfaces  36 ,  52 . In a preferred embodiment, the angle of the mating cone shaped components  36  and  52  is 30 degrees. The angle is designed to give sufficient centering forces for rotor  51  when rotor  51  and seat piece  30  are pressed together by the loading forces of the axial spring  60 . Rotor  51  is preferably constructed of an abrasion resistant, self-lubricating material that is chemically resistant to the fluids and service temperature, such as graphite filled polyetheretherketone (PEEK). Port-to-port sealing effectiveness is dependent on the precision and surface finish of the mating cone  52  and seat  30  and the normal force between the components. Rotor  51  is able to float axially to provide axial compliance if particles become entrapped between the sealing surfaces of conical valve seat  36  and a face of conical base end  52 . 
         [0023]    The fundamental valve design is uniquely flexible and scalable. Although the present configuration provides four-way directional control of slurries, the same design principles could readily be applied to an unlimited number of port configurations such as two-way, three-way, five-way, etc. Alternate materials could be used based on the necessary strength requirement and corrosion properties. Size is also scalable to accommodate various flow rates or slurry properties. 
         [0024]    One feature of the present invention includes cone shaped rotor  51 . The rotor  51  of the invention provides centralization and stability of rotor  51 . It is contemplated that valves having different shaped rotor and seat combinations such as flat or spherical, etc., may also be possible. 
         [0025]    Another feature of the present invention is large clearances around the rotor. The present invention has very large clearances around the rotor. This feature is essential for accommodating large particles without binding or becoming trapped. 
         [0026]    A third feature of the present invention is that pressure balance is achieved by having two ports connecting and flowing across the back side or stem end  54  of rotor  51  to counteract two ports on the front side or conical base end  52  of the rotor  51 . The balanced pressure promotes a constant rotor to seat sealing pressure which is provided by spring  60 . Spring  60  allows enough axial motion so that rotor  51  can ride up over particles rather than shear them or have them bind as rotor  51  is actuated. 
         [0027]    An additional feature of the present invention is flushing. The flow path across the top of the rotor continually flushes all cavities of the valve, thus eliminating the potential for particles to become trapped or lodged. 
         [0028]    A further feature of the present invention is that it has remarkably few parts, making it easy to service or rebuild. 
         [0029]    Additionally, the valve of the present invention is configurable for use over a broad temperature range. It is also suitable over a broad pressure range, including extremely high pressures. 
         [0030]    Further, the materials of construction for the valve design of the present invention are readily tailored to accommodate a broad range of chemical exposure. The size of the valve is scalable to accommodate various flow capacities. 
         [0031]    Thus, the present invention is well adapted to carry out the objectives and attain the ends and advantages mentioned above as well as those inherent therein. While presently preferred embodiments have been described for purposes of this disclosure, numerous changes and modifications will be apparent to those of ordinary skill in the art. Such changes and modifications are encompassed within the spirit of this invention as defined by the claims.