Abstract:
An aseptic product discharge valve and related methods for injecting steam into a sterile fluid delivery system used to transport a sterile fluid food product. The aseptic product discharge valve includes a tubular member having a longitudinal passageway and an outlet for discharging the flow of food product. The valve also includes a chamber disposed radially outward of the passageway. The chamber receives steam that is exhausted through an opening disposed adjacent to the valve. A valve member is disposed within the longitudinal passageway and fluid food product must flow about the valve member. The diverted flow of fluid food product may be intersected by the flow of injected steam. The tubular body further includes a valve seat which is bathed with the injected steam to promote sterility at the discharge location.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to aseptic valves and, more particularly, to an aseptic product discharge valve and related methods of preventing contamination of a fluid food product processing system by microorganisms. 
     BACKGROUND OF THE INVENTION 
     Many fluid food products are aseptically processed to prevent the undesirable effects of microorganism. Aseptic processing can significantly extend the shelf life of most foodstuffs and often involves the continuous sterilization of a fluid food product circulated within a closed process system. In a typical aseptic process, a fluid food product is thermally pasteurized by heating to an elevated temperature for a duration sufficient to reduce the viability of microorganism to acceptable levels. Following pasteurization, the fluid food product is typically transported through a cooling media before packaging into a sterile container. One example of such a system is shown and described in U.S. Pat. No. 5,802,96, which is assigned to the assignee of the present invention. In most processing and packaging operations, the cooling side of the system is much more prone to contamination by microorganism. One potential point of contamination is the occasional requirement to draw off a quantity of sterile product or other media from the sterile atmosphere of an aseptic cooling system to an unsterile atmosphere, such as an open tank or gutter. Over time, microorganisms can migrate up the discharge line and contaminate the system. 
     Conventional valves produce a fluid tight seal between a movable valve member and a complementary valve seat so as to discontinue or restrict flow. Absent suitable precautions, microorganisms resident in the discharge line downstream of the discharge valve can readily traverse the fluid-tight seal, invade the sterile piping system, and compromise the sterility of the closed process system. 
     Various manners of dealing with contamination issues in food processing systems have been utilized in the past. One typical system is a double block and bleed valve system which involves using two spaced apart valves in the discharge line with steam injection between the two valves. The valves are sequentially opened and timed with the introduction of stream to maintain sterility at the outlet. Unfortunately, this type of system is rather complicated and still may not maintain optimum sterility at the discharge location. 
     It would there fore be desirable to provide a product discharge valve, especially useful in the fluid food product industry, which combines simplicity of design with effective sterilization of the discharge location. 
     SUMMARY OF THE INVENTION 
     The present invention provides an aseptic product discharge valve that injects steam adjacent the interface between a valve member and an associated valve seat. The aseptic product discharge valve includes a tubular structure having a longitudinal passageway with an outlet for discharging the flow of the fluid food product. The valve further includes a chamber that is positioned radially outward of the longitudinal passageway and a steam conduit for supplying steam to the chamber. In one embodiment, the chamber is an annular chamber having an annular opening into the longitudinal passageway. The valve member may be moved by an actuating assembly configured to move the valve member between a closed position to prevent the flow of fluid food product through the outlet and at least one open position to allow the flow of fluid food product through the outlet. The actuating assembly may be a linear actuator coupled with the valve member by a valve stem. 
     The aseptic product discharge valve further includes a hollow valve stem having a cavity for receiving steam and a number of radial ports that perforate the hollow member. Steam at super-atmospheric pressure is delivered from a steam conduit attached for fluid communication with the valve stem that supplies steam to fill the cavity. The radial steam ports allow steam to bathe the full circumference of the downstream surface of the valve member. The steam injected from the opening in the annular chamber bathes the valve seat and the upstream surface of the valve member. The multiple steam injection locations form a barrier to the migration of microorganisms either along the inner surface of the discharge conduit or the outer surface of the valve stem, past the interface between the valve member and the valve seat. 
     Additional features, advantages and objectives of the invention will become more readily apparent to those of ordinary skill in the art upon review of the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a side view of an aseptic product discharge valve constructed in accordance with a preferred embodiment of the invention; 
     FIG. 1B is a side view of the embodiment shown in FIG. 1A, in which the flow of fluid food product has been blocked; and 
     FIG. 2 is an enlarged, fragmentary side view of FIG. 1A showing a section of the aseptic product discharge valve. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1A,  1 B and  2  show side axial cross sections of an aseptic valve, in accordance with the principles of the present invention, wherein the aseptic valve is configured to operate as an aseptic product discharge valve  110 . Referring to FIG. 1A, aseptic product discharge valve  110  generally includes a tubular body  112  featuring an internal annular chamber  114  that adapted to receive steam for injection, a valve assembly  116  disposed within tubular body  112 , and a valve actuator  118  attached to an opposite end of valve assembly  116 . 
     Tubular body  112  includes a longitudinal passageway  120  coupled for fluid communication with a passageway  122 . Longitudinal passageway  120  is an open space enclosed, in part, by a cylindrical wall  124  and extends along a longitudinal axis from a first up stream end  128  to a second downstream end  130 . Passageway  122  extends along a curvilinear axis toward an outlet  1   24  to an opening  130  in cylindrical wall  124 . First upstream end  128  of longitudinal passageway  120  is attached to a delivery conduit  132  for receiving a flow of a sterile fluid food product from a supply  139 , as shown by arrow  140 . Passageway  122  accepts fluid food product discharged from longitudinal passageway  120 , redirects the flow by approximately 90°, and exhausts the redirected flow through outlet  134  as shown by arrow  141 . Outlet  134  is circumscribed by an integral flange  138  adapted to attach in a fluid-tight manner to a complementary flanged end carried by a discharge conduit (not shown). 
     An inner tubular member  142  is disposed within longitudinal passageway  120 . In the embodiment shown in FIG. 1A, inner tubular member  142  is substantially coaxial and substantially concentric with longitudinal passageway  120 . Inner tubular member  142  includes a generally cylindrical wall  144  disposed radially inward from cylindrical wall  124  and has a first end  146  spaced apart from a second end  148 . A frustoconical rim or end  150  encircles the inner circumference of inner tubular member  142  near first end  146 . Rim  150  provides an annular beveled edge that functions as a valve seat, as will be dicussed below. 
     Annular chamber  114  comprises an open steam-receiving volume surrounding inner tubular member  142 . Second end  148  of inner tubular member  142  is circumferentially sealed in a fluid-tight fashion with the interior of cylindrical wall  124 . Annular chamber  114  includes an annular opening  152  disposed radially outward of frustoconical rim  150 . A steam conduit  154  penetrates cylindrical wall  124  to supply annular chamber  114  with steam at a super-atmospheric pressure generated by a remote steam source  155 . 
     Cylindrical wall  124  further includes integral flanges  158 ,  158   a  at respective first and second opposite ends  128 ,  130  that make a fluidtight seal with a Complementary flange. End  130  receives a flanged insert  160  having a central stepped bore  162  and a curvilinear interior face  164 . Angled face  164  sustains the streamline flow of fluid food product into passageway  122 . Fluid food product  139  that has been pasteurized upstream from valve assembly  116  to eliminate or substantially reduce entrained microorganisms is discharged from outlet  134 . 
     Valve assembly  116  is disposed within longitudinal passageway  120  and includes a valve stem  166  attached to the base of a valve member  168 . Valve member  168  includes a bulbous rounded surface  170  on the upstream side and an annular cusped surface  172  on the downstream side. Of course, the shapes and contours of surface  170  and surface  172  are not intended to be limiting in any way and may be varied without departing from the scope and spirit of the present invention. Valve member  168  is preferably composed of a stainless steel that can tolerate both the wear associated with the streaming food product and injected steam and the direct heat of the injected steam. 
     A portion of bulbous rounded surface  170  presents a sealing surface  173  that sealingly engages frustoconical rim  150  (FIG. 2) or, when separated from rim  150 , forms pathway  174 . Fluid food product emerges from annular pathway  174  as a thin diverging annular flow of fluid food product. The width of pathway  174  will contribute to establishing the flow rate of fluid food product through aseptic product discharge valve  110  and the radial thickness of the diverging annular flow. It may be appreciated by one of ordinary skill in the art that other geometrical configurations and shapes of sealing surface  173  and rim  150  are possible for varying the configuration of pathway  174 , the relative positioning of opening  152 , and the relative direction of the flow path of fluid food product without departing from the spirit and scope of the present invention. 
     Valve stem  166  extends axially away from an attachment point near the center of valve member  168  and through stepped bore  162 . A hollow bushing  178  is coaxially received within the larger diameter portion of stepped bore  162 . An O-ring  176  is carried by a circumferential groove formed in the inner surface of bushing  178 . O-ring  176  compressively engages a length of the outer surface of valve stem  166  to form a substantially fluid-tight dynamic seal. An opposite end of valve stem  166  is connected to an actuator finger  177  of valve actuator  118 . 
     As shown in FIG. 1B, valve stem  166  may further include a longitudinal cavity  179 . Steam is delivered at a super-atmospheric pressure to cavity  179  via a steam conduit  183  through a fitting  183 . A slot  182   a  allows back and forth movement of conduit  183 . Valve stem  166  further includes a plurality of radial steam ports  185  that vent s team outwardly from internal cavity  179  so that cusped surface  172  is bathed by steam. 
     Valve actuator  118  includes an outer housing  180  that attaches to flanged insert  160 . An opposite end of actuator finger  177  connects to a piston  184  that bisects a chamber  186  enclosed within outer housing  180  into two portions  186   a ,  186   b . Portion  186   a  includes a fitting  188   a  that extends through outer housing  180 . Fitting  188   a  is adapted to supply or exhaust pressurized gas through a conduit  190   a  coupled to a source  191  of the pressurized gas. A vent  190   b  is provided to vent air from chamber portion  186   b.    
     If pressurized gas fills chamber portion  186   a  as depicted in FIG. 1A, piston  184  will urge valve assembly  116  and separate valve member  168  from frustoconical rim  150  against the bias of a spring  189  in chamber portion  186   b . A ring  187   a  may be welded within housing  180  to carry a seal  187   b  engaged with finger or rod  177  to allow air pressure to build in chamber portion  186   a . When the pressurized gas is exhausted as depicted in FIG. 1B, valve assembly  116  will be forced by spring  189  in an opposite direction so that valve member  168  contacts rim  150  and the flow of fluid food product is at least substantially blocked. In such a contacting state, sufficient force must be applied to piston  184  so as to resist the countervailing force applied by the static pressure of food product located upstream of valve member  168 . 
     FIG. 2 schematically illustrates the flows of fluid food product and steam through a segment of longitudinal passageway  120  proximate to valve member  168 . In operation, fluid food product that has been sterilized is received by conduit  132 . When valve assembly  116  is actuated to a closed position, a steam is admitted into internal cavity  179  and into annular chamber  114 . Alternatively, steam may be continuously admitted into internal cavity  179  regardless of whether valve assembly  116  is actuated to a closed position or an open position. If the steam is draining under gravity to a waste receptacle, steam must be provided to annular chamber  114  at a pressure of greater than about 5 psi to establish a positive flow of steam. However, a greater pressure of steam may be required if the flow must overcome a hydrostatic barrier. 
     Steam exits annular opening  152  as a thin annular flow that bathes the backside of frustoconical rim  150  and a peripheral annulus of bulbous rounded surface  170 . The flow of steam is indicated by arrows  196 . Steam is simultaneously emitted as indicated by arrows  194 , from each radial steam port  185  to bathe annular cusped surface  172 . The two converging baths of steam form an effective thermal barrier. The steam also eliminates or aseptically reduces microorganisms migrating from the discharge line into passageway  122 . The pressure and temperature of steam in steam conduits  154 ,  183  (FIG. 1B) may be regulated by valves interfaced with control circuitry (not shown). While not shown, it will be appreciated that the control circuitry is well known to one of ordinary skill in the art and includes appropriate components for operating aseptic product discharge valve  110 . 
     While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant&#39;s general inventive concept.