Abstract:
In order to drastically improve the functionality of flow control, externally-pressurized porous media gas bearings is introduced into valves. The porous media gas bearings mitigate two of the biggest issues with the current technology, which are: (1) leakage of fugitive emissions, and (2) high breakaway torque values for actuating valves. By employing externally-pressurized porous media bearings, fugitive emissions are completely eliminated, and valves can be rotated effortlessly due to the non-contact nature of porous media gas bearings.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/132,719, filed Mar. 13, 2015, whose disclosure is hereby incorporated by reference in its entirety into the present disclosure. 
     
    
     FIELD OF INVENTION 
       [0002]    This application is generally related to the actuation of a variety of valve types and sealing the same from escaping fugitive emissions. The valves most benefitting from the subject invention include, but are not limited to, plug valves, butterfly valves, gate valves, valves used in the oil and gas industry, in refineries, in power plants, in chemical plants, in waste process plants, in applications where sealing of gases is critical, and in applications which currently require significant torque for opening and closing valves. 
       BACKGROUND 
       [0003]    Valves are used to prevent, permit, or regulate the flow of gases, liquids, powders, or slurries. Two key issues with state-of-the-art valves include: (1) the release of fugitive emissions (as in the case of valves that are intended to regulate gases, and (2) the fact that certain valves, especially large valves, oftentimes require a high amount of torque during opening, adjusting or closing of the valve. 
         [0004]    The Environmental Protection Agency has made continued efforts to reduce and regulate the release of fugitive emissions. However, this still involves the fact that almost all valve stems are sealed using “packing” material. Over time, the packing needs to be replaced to maintain EPA compliance, and valve leakage must be monitored as part of the EPA&#39;s Leak Detection and Repair (LDAR). Regardless of how good the packing is, no technology is considered leak-free with zero emissions. 
         [0005]    With regard to operating valves, especially via handwheels, the breakaway torque values required are often quite high, and require special tools or equipment for actuating the valves. Without special tools or equipment, manual operation of a handwheel can require more than one person in order to actuate certain valves, due to the high breakaway torques. There have been studies performed indicating that human factors, such as musculoskeletal problems, can occur due to physical exertion associated with manually operating valves with high breakaway torque values. Current solutions used to avert such human factors include equipment such as cable drive systems to actuate valves, portable valve actuators, and a plethora of actuation equipment powered by pneumatic, hydraulic, or electric power. 
         [0006]    In brief, valve assemblies have not changed much in the last 100 years. And, inherent in these old, basic designs are some of today&#39;s biggest problems: fugitive emissions and hard-to-actuate valves. The current art has not had a good redesign which will get to the root of these two issues. 
       SUMMARY 
       [0007]    Briefly stated, the invention utilizes porous materials as a restrictive element to a pressurized fluid or gas to the bearing/sealing lands in a valve. This pressure reduces or eliminates friction between the stationary and moving surfaces. 
         [0008]    The subject invention alternatively uses gas-pressurized porous media bearing gaps to prevent the escapement of fugitive emissions, by virtue of the fact that the supplied aerostatic gas pressure will present a barrier at the face of the porous media, opposing any fugitive emissions. 
         [0009]    In the case of valve actuation, the use of externally, aerostatic-gas-pressurized porous media, acting as an air bearing, essentially will create a non-friction surface, which will allow valves to be actuated by hand, with virtually no breakaway torque. 
         [0010]    The subject invention solves several key issues contained in the current art: (1) it eliminates fugitive emissions completely by invoking the use of externally-pressurized porous media as a bearing and seal, and (2) the use of externally-pressurized porous media allows for effortless, manual operation of valves, without the need for special equipment or tooling for overcoming high breakaway torque values. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The foregoing summary, as well as the following detailed description of the preferred embodiments, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are particular embodiments and configurations shown in the drawings. It should be understood, however, that the scope of invention is not limited to the precise arrangement shown. 
           [0012]      FIG. 1  shows an example of a prior art valve stem with the sealing feature being packing material. 
           [0013]      FIG. 2 . shows an example of a prior art plug (or similar) valve. 
           [0014]      FIG. 3  shows an example of a valve stem with the sealing feature being externally-pressurized porous media, also allowing ease-of-rotation 
           [0015]      FIG. 4A  shows an example of a plug valve using externally-pressurized porous media as a sealing and bearing feature 
           [0016]      FIG. 4B  shows porous media for a face seal. 
           [0017]      FIG. 4C  shows porous media for an angled seal/seat. 
           [0018]      FIG. 4D  shows porous media for a spherical seal/seat. 
           [0019]      FIG. 5  shows an example of a valve which uses externally-pressurized porous media as a bearing feature, and having a containment with a magnetic-drive feature to prevent emissions. 
           [0020]      FIG. 6  shows an example of an externally-pressurized porous media face seal to prevent emissions. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    Certain terminology is used in the following description for convenience only and is not limiting. The words “front,” “back,” “left,” “right,” “inner,” “outer,”  “ upper,” “lower,” “top,” and “bottom” designate directions in the drawings to which reference is made. Additionally, the terms “a” and “one” are defined as including one or more of the referenced item unless specifically noted otherwise. A reference to a list of items that are cited as “at least one of a, b, or c” (where a, b, and c represent the items being listed) means any single one of the items a, b, or c, or combinations thereof. The terminology includes the words specifically noted above, derivatives thereof, and words of similar import. 
         [0022]    As illustrated in  FIG. 1 , prior art valve stems are comprised of a stem  101 , a valve body  102 , a yoke  105 , a gland follower  104 , a gland stud  106 , and packing  103 . In order to seal the valve stem  101  from allowing emissions to the atmosphere from the valve, the gland stud  106  is tightened, which, in turn, creates a downward force on the yoke  105  and gland follower  104 , and eventually compresses the packing  103  so that it forms a seal around the stem  101 . In time, the packing  103  will begin to relax, and will leak, at which point the gland stud  106  will need re-tightened. Eventually, the packing  103  will leak to the point that the packing will need to be replaced. 
         [0023]    Another example of prior art is illustrated in  FIG. 2 , which illustrates a typical plug valve, which allows or prevents flow when the valve is rotated. The  FIG. 2  plug valve is comprised of a valve body  202 , a plug  201 , sleeves  203  and  204  which act as a sealing mechanism, a collar  205  which also acts as a sealing mechanism, and a possible seal/seat  206 . Other types of valves, such as gate valves, ball valves, and others all have sealing surfaces or valve seats which have a similar function as the sleeves  203  and  204 , the collar  205 , and the seal/seat  206  as shown in  FIG. 2 . There are two issues with the current technology. First, the sealing is not leak-proof, and thus fugitive emissions result. Furthermore, the seals or valve seats wear and require replacement in time. Additionally, the materials used for current art seals and valve seats are not conducive to higher temperatures. Regarding the second main issue, the current art sleeves, seals, or seats may cause the valves to have high breakaway torques which become problematic for operators, as described earlier. 
         [0024]      FIG. 3  illustrates how an externally-pressurized porous media cylindrical member can be used to provide valve stem sealing which prevents fugitive emissions. This illustration is comprised of valve stem  301 , valve body  305 , a porous media seal  302 , a port  303  for externally-pressurized incoming gas, a plurality of plenums  309  that distribute the pressurized gas to the porous media, a yoke  306 , studs  307 , and a cylindrical gap  304  between a cylindrical member and valve body  305 . For this arrangement, the porous media seal  302 , which is substantially in the form of a cylinder, is installed in the valve body  305 . The yoke  306  functions to hold the porous media seal  302  in place to prevent axial movement under pressurization. The studs  307  hold the yoke in place. Optionally, the cylindrical gap may be filled with epoxy to rigidly hold the cylindrical member to within the valve body. 
         [0025]    Externally-pressurized gas is introduced via port  303 , and is directed through the plurality of plenums  309 , and into the porous media seal  302 . The pressurized gas flows through the porous media seal  302  and creates a very thin gap of pressurized gas between the outside diameter of the valve stem  301  and the inside diameter of the porous media seal  302 . As long as the pressure in this gap exceeds any opposing pressure coming from the valve, leakage will be prevented from coming out of the valve stem  301 , and therefore fugitive emissions will be prevented. 
         [0026]      FIG. 4  illustrates how porous media technology can be used in a plug valve for the purpose of providing sealing, as well as having frictionless turning capability. Porous media cylindrical seals  403  and  404  or face seals  405 A and  405 B are inserted in valve body  402 . Several possibilities exist during operation. Externally-pressurized gas is injected into the porous media seals  403  and  404  or  405 A and  405 B in the same manner as described in  FIG. 3 . The pressure in the air gap between the seals  403 ,  404  or  405 A and  405 B and the seal body  402  is maintained at a pressure which is higher than the pressure flowing through the valve. Hence, when the plug  401  is shut, the gap pressure is higher than the pressure of the fluid flowing into the valve, and the fluid is not able to penetrate the higher pressure in the air gap. When the plug  401  is in the open position, the air gap pressure is still higher than the flowing fluid pressure, and the flowing fluid is unable to leak past the seals  403  and  404  or  405 A and  405 B. Furthermore, the air gap produced by the introduction of externally-supplied gas pressure into the seals  403  and  404  or  405 A and  405 B creates a non-friction condition at the plug interface which allows the plug  401  to be effortlessly turned to the open or closed positions. This is hereby contrasted with the current art&#39;s high breakaway torques that often exist when trying to turn such valves. The teaching shown for  FIG. 4  has far reaching applications to other types of valves, such as gate, ball, and other types of valves wherein the porous media seals can replace valve seats, thus enabling both sealing and ease of rotation. 
         [0027]      FIGS. 4B, 4C and 4D  show porous media arrangements for a face seal  470 , an angled seal/seat  480  or a spherical seal/seat  490 , respectively. In  FIG. 4B , housing  407  comprises a channel  409  that directs injected gas into plenums  408  and into porous media  406 . In  FIG. 4C , housing  413  comprises a channel  412  that directs injected gas into plenums  411  and into porous media  410 . In  FIG. 4D , housing  416  comprises a channel  417  that directs injected gas into plenums  415  and into porous media  414 . 
         [0028]      FIG. 5  is an illustration which builds upon the teaching of  FIG. 4 , but also introduces a further novelty pertaining to sealing functionality. Gas bearing sleeves  502  and  503  are installed into valve body/containment  504 , and these seals function on the basis of externally-pressurized gas in the same ways as presented in  FIGS. 3 and 4 . Plug  501  is connected to a driven magnet  505 , which is acted upon by magnetic force via a driving magnet  506  through the valve body/containment  504 . The driving magnet is installed in a casing  507  which is attached to a shaft  508 . 
         [0029]    During operation, the casing  507  and driving magnet  506  are rotated, causing a magnetic field to act upon the driven magnet  505 , thus causing the valve plug  501  to rotate to the open or closed position. The externally-pressurized gas bearing sleeves  502  and  503  allow the valve to open or close effortlessly due to the air gap created by pressure in the air gap which is higher than the pressure of the fluid in the valve. When the valve reaches its intended open or closed position, gas pressure supplied to the gas bearing sleeves  502  can be shut off. The valve will continue to perform its function in the open or closed position. When it is desired to actuate the valve from the opened-to-closed, or closed-to-opened position, the externally-supplied pressure to the gas bearing sleeves  502  and  503  is turned on, and the valve plug  501  instantly pops free by virtue of the air film created at the bearing-to-plug interface, thus allowing the valve to be operated in a frictionless manner. Furthermore, the valve body/containment prevents any leakage out of the valve at all times. The teaching shown for  FIG. 5  has far reaching applications to other types of valves, such as gate, ball, and other types of valves wherein the porous media bearings can replace valve seats, thus enabling ease of rotation, as well as the fact that the magnet-containment methodology can provide sealing at all times. 
         [0030]    An alternative face type seal is presented in  FIG. 6 . In this arrangement, a runner  607  is coupled to a rotating shaft  601  (which could be a valve stem) by an O-ring  613 . On opposing sides of the runner  607  are two porous media seal faces  609  and  610 . These face seals are installed into housings  604  and  606 , and are supplied with externally-pressurized gas via ports  614  and  615 . The externally-pressurized gas flows into plenums  608  and  611 , and then flows through the porous media seal faces  609  and  610 . The pressure introduced into the seal faces creates an air gap between the seal faces and the runner, which maintains a pressure which is higher than the opposing pressure which leaks up to this point from the valve. The gap pressure causes the fluid or gas in the valve to not be able to penetrate, and hence the valve stem is completely sealed. Adjacent to the runner  607  is spacer  605 , which separates the two housings  604  and  606 , and these components are all held together by bolts  612  (it should be noted that while only one bolt is shown, the assembly may use 4 or more such bolts). The seal assembly is attached to the valve body  602  via certain number of the  612  bolts which penetrate through the entire seal assembly and into the valve body  602 . In certain cases optional adaptive mounting member  603  and bolts  616  may be required. 
         [0031]    In addition to the sealing functionality taught above, the  FIG. 6  arrangement is also able to be used as a non-contact thrust bearing for rotating equipment. That is, by attaching the runner  607  to a rotating shaft  601 , the faces  609  and  610  act as non-contact axial bearing faces. The externally-pressurized gas to the faces  609  and  610  create an air gap between the runner  607  and seal faces, and is capable of bearing axial loads imparted on the rotating shaft. It is noted that the attachment of the runner  607  to the shaft  601  can be accomplished with hard-mounting in lieu of O-ring  613 . In such case, a set screw or thrust collar, as is typically known in the art, can be used. 
         [0032]    While preferred embodiments have been set forth in detail with reference to the drawings, those skilled in the art who have reviewed the present disclosure will readily appreciate that other embodiments can be realized within the scope of the invention, which should therefore be construed as limited only by the appended claims.