Patent Publication Number: US-2022228604-A1

Title: Gas compressor with reduced energy loss

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from U.S. Provisional Patent Application No. 62/850,484, filed May 20, 2019, entitled “Gas compressor with Reduced Energy Loss,” and U.S. patent application Ser. No. 16/418,535, filed May 21, 2019, entitled “Energy Recovery-Recycling Turbine Integrated with a Capillary Tube Gas Compressor.” 
    
    
     TECHNICAL FIELD 
     Gas compression systems and, more particularly, internal recirculating centrifugal gas compression systems. 
     BACKGROUND 
     In a centrifugal gas compression system, liquid and gas are moved from an inner area to an outer area of a rotating drum. As the liquid and gas move in this manner the gas is compressed and separated from the liquid as it reaches the outer area. Some systems recirculate the liquid from the outer area to the inner area of the system. When the liquid is recirculated externally, meaning outside of the rotating drum of the system there is very little to no energy recovered from the energy input to operate the system. When liquid is recirculated within the drum, such as through a rotating turbine, energy can be recirculated as well, but that energy is recirculated external to the drum. To recover this energy and recirculate it to the drive of the compressor, some type of electrical or mechanical power transmission system is required. It would therefore be desirable to recirculate both liquid and energy without requiring a power transmission system. 
     The channels through which liquid and gas are moved from the inner area to the outer area are generally tubular. Small capillary tubes may help to force entrained bubbles of gas to be compressed between plugs of liquid. Valves within the tubes or tapered transitions along the tubes may help to prevent gas from leaking back toward the inner area. Capillary tubes, with or without flow restrictions, may be more difficult and costlier to manufacture and present increased energy losses than larger diameter tubes or channels. 
     SUMMARY 
     A gas compressor is disclosed comprising a substantially hollow cylindrical drum having one end affixed to a shaft configured to rotate the drum. The drum includes a compression channel assembly including a plurality of compression channels extending from an opening at a common pressure zone toward an interior surface of the drum distal to an axis of rotation. A static vane return (SVR) positioned adjacent the compression channel assembly has an outlet to the common pressure zone and one or more vanes extending from an inlet at an outer circumference of the SVR, which does not rotate with the drum. A ducted spacer block positioned adjacent the SVR may form one or more channels configured to direct gas into the SVR. Rotation of the drum causes fluid inside the drum to form an annular lake. Fluid is drawn from the lake through the vanes and into the common pressure zone where the fluid is forced into the opening of the compression channels, wherein gas in the fluid within each compression channel is compressed as it travels from the common pressure zone toward the interior surface. The pressurized gas is separated from liquid prior to leaving the compression channel assembly. The liquid is returned to the lake. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings are provided to illustrate example embodiments described herein and are not intended to limit the scope of the disclosure. 
         FIG. 1  is a perspective view of a compressor assembly in accordance with an embodiment; 
         FIG. 2  is a side cross-sectional view of the compressor assembly of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the drum section of the compressor assembly of  FIG. 2  and further illustrating gas and liquid process flow; 
         FIG. 4  is a perspective view and a cross-sectional view of a static vane return assembly of the drum section of  FIG. 3 ; 
         FIG. 5  includes perspective, cross-section and top view of the static vane return of the static vane return assembly of  FIG. 4 ; 
         FIG. 6  includes perspective and translucent illustrations of the gas inlet duct body of the static vane return assembly of  FIG. 4 ; 
         FIG. 7  is a cross-sectional view of the drum assembly of the compressor assembly of  FIG. 2 ; 
         FIG. 8  includes cross-sectional views of portions of the V-block plate of the compressor assembly of  FIG. 2 ; and 
         FIG. 9  is a top perspective, cross-sectional view of a portion of the V-block plate of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     Devices, systems and methods are described herein for compressing gas through centrifugal action of a shaft driven compressor drum containing a liquid and a gas. In an energy recovery system for a centrifugal gas compressor that includes a rotating turbine, there may be high liquid pressure at the inlet, but the pressure may drop as the liquid moves toward the outlet, where a velocity of the liquid may match the speed of the compressor drum. As a result, the system may be optimized for power recovery from torque applied to a shaft of the turbine, which may then be transferred to a power transmission system and fed back to the drive for the compressor drum. 
     A different type of energy recovery system for a centrifugal compressor  10  is disclosed herein with reference to the Figures.  FIG. 1  illustrates the exterior of compressor  10 , which includes a static vane return (“SVR”) assembly  12  in place of a rotating turbine assembly. In the disclosed system, fluid pressure may be lower at the inlet to the SVR assembly  12  and remain that way as the fluid moves toward the outlet of the SVR assembly, and the velocity of the fluid may initially correspond to the rotation speed of the drum of the compressor and a radial position of an inlet of the SVR assembly  12 . This type of system may be optimized for fluid momentum conservation, with energy being returned directly to the compressor drum  14  without the need for any type of additional power transfer system, which may result in reduced energy consumption. As the compressor  10  with the SVR assembly  12  has fewer moving parts than a compressor with a rotating turbine system, it may also be easier and less expensive to manufacture. 
     The SVR assembly  12  may be supported by a cage assembly  16 . The rotating compressor drum  14  may be turned by a shaft assembly  18 . A drive system (not shown) may provide power to the shaft assembly  18 . Before power is applied to the shaft assembly  18 , the compressor drum  14  may be filled approximately halfway with a fluid such as a liquid, such as water or a petrochemical, or a liquid and gas. The compressor drum  14  and the contained fluid may then be rotated by the drive and lower shaft assembly  18  until the fluid is forced against the interior wall of the compressor drum  14  by centrifugal forces, forming an annular lake over the interior wall. 
       FIG. 2  illustrates an embodiment of at least a portion of the interior of the compressor  10 . The SVR assembly  12  includes the mounting column  20  and the static vane return (SVR)  21 . In an embodiment, rotation of the compressor drum  14  may cause gas external to the compressor drum  14  to be pulled into the compressor  10  through an opening, such as in the top or upper portion of the compressor  10 , and directly into the SVR  21 . Although reference is made herein to the compressor  10  being vertically aligned, wherein the first end of the compressor  10  or one of its components is essentially the top or upper portion of that component and the second end is the opposite end, i.e., the bottom or lower portion of that component, it will be appreciated that the compressor  10  may operate in a horizontal or other alignment, such that the first end is one side and the second end is an opposite side. 
     In an embodiment the SVR assembly may also include the ducted spacer block  22 . The ducted spacer block  22  may have a first end that extends through an opening in a first end of the compressor drum  14  and is connected to the mounting column  20 . A second (i.e., opposite) end of the ducted spacer block  22  may be connected to a first end of the SVR  21 . Gas may enter the mounting column  20  and be pulled into the compressor through gas inlet channels  23  or gas may be pulled around a shield ring positioned around the ducted spacer block  22  (shown as shield ring  46  in  FIG. 4 ) and into the SVR inlets  52 A. 
     In an embodiment, and as more fully illustrated in  FIG. 6 , there may be four gas inlet channels  23  that start where the first end of the ducted spacer block  22  connects to the mounting column  20  and that may be configured to route incoming gas through the mounting column  20  into the compressor drum  14 , although any number of channels may be used as appropriate for a desired gas flow and the routing flow may be different. The gas inlet channels  23  may not be needed when gas is pulled around the shield ring. 
     A compression channel assembly  24  may be positioned inside the compressor drum  14  such that the first end of the compression channel assembly  24  is next to but separate and apart from the second end of the SVR  21 . A gas harvest plate  25  may be positioned at the second end of the compression channel assembly  24 . The gas harvest plate  25  may be connected to first end of the shaft  26 . The second end of the shaft  26  may be connected to a gas harvest nipple  28 . 
     The inside of the compressor drum  14  is further illustrated in  FIG. 3 . As noted, the first end of the compressor drum  14  may include a compressor drum lid  30  that includes an opening for the ducted spacer block  22 . The cylindrical outer side portion of the compressor drum  14  may be formed by the rotating housing  31 , which may form an open central area  32  having a first end at the compressor drum lid  30 . The compression channel assembly  24 , which is more fully described below, may sit at the second opposite end of the open central area  32  from the compressor drum lid  30 . A drum plate  34  may form the second opposite end of the compressor drum  14 . Between the compression channel assembly  24  and the drum plate  34  may be the gas harvest plate  25 , which may include gas harvest passage  36 , as further explained below. In an embodiment with no ducted spacer block  22 , the compressor drum  14  may have a more compact design. 
       FIG. 4  further illustrates the SVR assembly  12 . The SVR assembly  12  may be a static or non-rotating device that may be used to return (i.e., recycle) fluid from the outer side portion of the compressor drum  14  to the center of the compressor drum  14 . The SVR assembly may also draw gas into the compressor  10  and may pre-pressurize that gas before being further compressed within the compression channel assembly  24 . The SVR assembly  12  may also balance gas and fluid levels within the compressor  10 , adding or removing gas and fluid to and from a common pressure zone as needed, as further described herein. As shown in FIG.  4 , the mounting column  20  may be circumscribed by a mounting flange  40  that may be affixed to the cage assembly  16 , as shown in  FIG. 1 . The ducted spacer block  22  may have a first portion  42  that includes one or more ducts  23 , a second opposite portion  44 , and a seal plate  46 . 
     During operation, fluid fills the gap between the seal plate  46  and the compressor drum lid  30  to form a water seal. As the annular lake level increases, the lake essentially acts as a p-trap that contains the pressurized gas within the compressor drum  14 . As previously noted, the SVR  21 , which is more fully illustrated in  FIG. 5 , may be affixed to the bottom of the ducted spacer block  22 . 
       FIG. 5  provides more detailed views of the SVR  21  in accordance with an embodiment. As will be more fully explained below with reference to  FIG. 7 , as fluid is added to the compressor drum  14 , the fluid level of the annular lake may move higher, meaning towards the center of the compressor drum  14 . Eventually, the fluid level may rise to the level of the vanes  50 , at which point the fluid may enter the vanes  50  at the inlet  52 A. Although there are four vanes  50  shown in the embodiment, there may be less than four vanes, including a single vane if properly balanced, or more than four vanes in other embodiments. Penetrations or ducts (not shown) in the embodiment of SVR  21  shown in  FIG. 5  may also be provided in an embodiment. Such penetrations or ducts may pitot ducts, liquid make up ports, a pressure relief ports as further described herein. Such penetrations or ducts in the SVR  21  may be similar to the penetrations or ducts of the ducted spacer block  22 , as further described herein. As the fluid level increases within the compressor drum  14  the vanes  50  may become submerged and fluid may be drawn from the lake into the SVR  21 . At the same time, pitot ducts (shown but not labeled in  FIG. 4 , and further described below) positioned near the vanes  50  in the SVR  21  or in a second portion  44  of the ducted spacer block  22  may allow removal of fluid from the drum, potentially to drain off excess fluid or implement a cooling system. 
     Fluid and possibly low-pressure gas may exit the vanes  50  at the outlets  52 B. The vanes  50  may have a substantially constant cross-sectional area, although the orientation may change from vertical to horizontal from the outer circumference of the SVR  21  to the interior area of the SVR  21 . For example, the vane  50  may ramp downward from the inlet  52 A at the top of the SVR  21  toward the bottom of the SVR  21  but become substantially level at the outlet  52 B. As a result, the fluid flow at the outlet  52 B may be substantially tangentially and downward. Other shapes, orientations and arrangements of the vanes  50  are possible. 
     The second end of ducted spacer block  22  may be mated to the first end of SVR  21  such that the gas inlet channels  23  of the ducted spacer block  22  may be matched to the SVR gas intake ports  54  of the SVR  21 . The fluid spinning in the compressor drum  14  may be traveling very fast relative to the inlet gas as the fluid enters the vane  50 , which may cause the incoming gas to achieve some fraction of the fluid velocity while moving through the vanes  50 . This action may serve to draw gas into the SVR inlet  52 A along with the fluid and may pre-pressurize gas in the fluid as it enters a central inlet chamber  56 . 
       FIG. 6  provides a more detailed illustration of the ducted spacer block  22  which may include a number of different penetrations, including the four gas inlet channels  23 , two pitot ducts  60 , a liquid make up port  62 , a pressure relief port  64  and four bolt holes  66 . The bolts hole  66  may pass all the way through the ducted spacer block  22  from the first end to the second end so that the ducted spacer block  22  may be sandwiched between the SVR  21  and the mounting column  20 . The gas inlet channels  23  may be formed so as to allow an adequate volume of gas to pass into the compressor  10 . The gas inlet channels, together with the mounting column  20  may make it possible to plumb the compressor  10  directly from a gas source, to allow the compressor to operate in an ambient atmosphere, and to allow the compressor to be fed with gas from another source. As noted above, the pitot ducts  60  may make it possible to remove fluid once their inlets are partially or fully submerged. 
     Turning now to  FIG. 7 , the operation of the compressor  10  may be explained. Once the compressor drum  14  has been roughly half filled with fluid, the shaft may be rotated in the direction of rotation (H). Such rotation of the compressor drum may cause the fluid to be forced against the interior wall of the rotating housing  31  (as shown in  FIG. 3 ) by centrifugal force (F). As the fluid is spun against the interior wall of the rotating housing  31 , the level (B) of the fluid may be perpendicular to the direction of rotation (H). The level (B) may be adjusted by adding fluid through the liquid make up port  62  at (I) or by removing fluid with the pitot ducts  60 , as further illustrated in  FIG. 6 . 
     When the level (B) of the fluid has reached the edge of the SVR  21 , a portion of the fluid (C) may be diverted into the vanes  50  of the SVR  21  and may be forced into the central inlet chamber  56  (K). If the fluid is just liquid or a combination of liquid and gas, the rotation of the drum and the resulting velocity of the liquid/fluid (C) relative to the gas (A) may result in low pressure gas being drawn into compressor  10 , such as between the top of the compressor drum  14  and the ducted spacer block  22  and/or through the gas inlet channels  23  (D), and into the central inlet chamber  56  (K) along with the liquid/fluid (C). Pulling the low pressure gas (A) into the compressor with the high velocity liquid/fluid (C) may pre-pressurize the gas in the central inlet chamber  56  (K) upstream of the compression channels of the compression channel assembly  24 . If pressure in the central inlet chamber  56  (K) exceeds a threshold, pressure may be released through the pressure release port  64  (E). Although reference is made to the central inlet chamber (K) being a central opening formed in the SVR  21 , the central inlet chamber (K) includes the joining of the openings formed in the middle of the compression channel assembly  24  and the top of the gas harvest plate  25 , as more clearly illustrated in  FIGS. 3 and 7 . 
     From the central inlet chamber (K), fluid may be forced through the inlets of the compressions channels (L) of the rotating compression channel assembly  24  by mixing and centrifugal force (F) on the fluid portion of the resulting emulsion. As further explained below, the gas in the liquid/gas fluid emulsion may be compressed within the compression channel assembly  24 . As the fluid emulsion may leave the outlets of the compression channels (L) the compressed gas (G) and the liquid (C) may immediately separate due to their differing densities. The liquid (C) may return to the annular lake in the compression drum, thereby returning rotational energy in the liquid back to the compressor. The compressed gas (G) may be captured and diverted off as further explained with reference to  FIG. 8 . 
     The compression channel assembly  24 , illustrated by the various images in  FIG. 8 , may utilize a plurality of radially arranged channels with rectangular cross-sections and agitators, rather than capillary tubes or other forms of tubes. The channel architecture may allow for a higher gas flow, while requiring less energy in comparison to prior designs. The compression channel assembly  24  may include a collar  80 , a top plate  82 , a bottom plate,  84 , and a plurality of V-shaped blocks  86 . The collar  80  may act as a duct for the incoming fluid and a spacer down to the top of the plate, but may be shortened if a larger (i.e., thicker) plate was desired for greater capacity. 
     The top plate  82  may act as a pressure plate for trapping the pressurized gas as it separates from the liquid at the outlets of the compression channels. The bottom plate  84  may act as a pressure plate and a gas harvest porting system to the gas harvest plate  25  mounted below. The V-shaped blocks  86  are illustrated in two different embodiments. The V-shaped blocks  86 A may be formed of a single manufactured block, such as by machining, casting, molding or even printing. The V-shaped block  86 B may be formed from a series of plates with various cross-sections stacked up to create the block assembly. One side of each V-shaped block may be smooth while the other side may include various geometric surface features that may increase gas entrainment (i.e., the separation of gas bubbles between blocks of fluid which serves to compress the gas as the liquid is forced outward by the centrifugal force (F)) and liquid friction within the channels. Both sides of the V-shaped blocks may be textured or geometrically surfaced. The underside of the bottom plate  84  may include a groove  87  further explained below. 
     As more fully explained with reference to  FIG. 9 , the compression channels  90  are formed between each of the V-shaped blocks  86 . As the emulsion of fluid in the central inlet chamber  56  enters the emulsion inlets  92 , liquid in the fluid may be slammed against the trailing walls of the compression channels  90  and pushed down along the length of each compression channel  90  by rotation of the compressor drum  14 . Gas in the fluid entering each compression channel  90  may be pulled downward by the rushing liquid. The two streams of liquid and gas may meet at a fluid level determined by the overall liquid column (M) (as shown in  FIG. 7 ) in the compressor drum. The liquid column (M) may act like a waterfall where actual gas entrainment occurs. Prior to arriving at the liquid column (M), the differing densities and centrifugal forces may act to keep the gas and liquid in the fluid largely separated. A venturi-type or eductor-type inlet emulsifier (not shown) may be used to feed the compression channels  90  and may have the potential for increasing the gas/liquid ratio and thereby reduce hydrodynamic drag. 
     Small surface features  95  in the compression channels  90  may operate as agitators or simply add friction that may assist in the gas compression. The emulsion outlets  94  at the end of each compression channel  90 , are below the level of the liquid column (M) where the waterfall exists, may be smooth and taper or narrow to increase the flow velocity as the emulsion leaves the compression channels  90 . The velocity increase may aid in overcoming the bubble rise velocity (i.e., the tendency of the gas bubbles to float back up the channels  90  rather than be pushed down and compressed within the compression channels  90 ) and therefore help to move the gas from the compression channels  90  to the separation chambers  96  formed within the “V” of each V-shaped block. For the same intended purpose of overcoming the bubble rise velocity, the compression channels  90  may also be swept or angled backwards with respect to the rotation direction of the channel assembly  24 . The leading side of each emulsion outlet  94  may have a slightly lower or filleted top that may promote gas flow from the compression channels  90  toward the corresponding separation chamber  96  before the emulsion leaves the volume between the top plate  82  and bottom plate  84 . A common pressure, and therefore a common liquid column (M), should be maintained across all of the V-shaped blocks to avoid creating any imbalances in the compressor  10 . 
     A small hole formed in the bottom plate  84  may form a separate gas harvest port  99  for each separation chamber  96 . The hole may be formed at any of a number of locations. Each of the gas harvest ports  99  may communicate with a common groove  87  on the underside of the bottom plate  84 . The groove  87  may align with a common groove (shown in  FIG. 3 ) in the gas harvest plate  25 . In some embodiments the bottom plate  84  and gas harvest plate  25  may be combined as a single part. During operation, pressurized gas (G) (in  FIG. 7 ) may be captured within the separation chambers  96  and pass through the gas harvest ports  99  into the common grooves formed between the bottom plate  84  and the gas harvest plate  25 . The pressurized gas (G) may then move into an opening (shown in  FIGS. 2, 3 and 7 ) in the lower shaft  26 , through the lower shaft  26 , and out of the compressor  10  through the gas harvest nipple or valve  28 . 
     In an embodiment, the gas compressor may comprise a substantially hollow cylindrical drum having a first end and a second end opposite the first end. The second end may be affixed to a shaft configured to rotate the drum. The drum may include a compression channel assembly defining a plurality of compression channels, each compression channel extending from an opening at a common pressure zone toward an interior surface of the drum distal to an axis of rotation. The compressor may also include a static vane return positioned adjacent the compression channel assembly and having an outlet to the common pressure zone. The static vane return may be configured not to rotate with the drum. 
     The static vane return may include at least one vane extending from an inlet at an outer circumference of the static vane return to the common pressure zone. The compressor may further include a ducted spacer block positioned adjacent the static vane return and one or more channels into or returning from the static vane return. The ducted spacer block may be configured not to rotate with the drum. Rotation of the drum may cause a fluid inside the drum to form an annular lake having a fluid level. When the fluid level reaches the inlet of the at least one vane, fluid may be drawn from the annular lake through the at least one vane and into the common pressure zone, where the fluid may be forced into the opening of each compression channel. Gas in the fluid within each compression channel may be compressed as it travels from the common pressure zone toward the interior surface. The pressurized gas may be separated from liquid in the fluid prior to leaving the compression channel assembly while the liquid is returned to the annular lake. 
     In the embodiment, wherein the compressor further includes a pressurized gas harvesting system that may be configured to separate the pressurized gas from the liquid. The pressurized gas harvesting system may include a plate adjacent the compression channel assembly, the plate may include passages formed therein and may be configured to receive the pressurized gas from the compression channel assembly. A first end of the passages of the plate may align with openings formed in the compression channel assembly and a second opposite end of the passages may connect to a gas harvest valve. 
     In the embodiment, wherein the compression channel assembly may include a plurality of V-shaped blocks positioned to form each compression channel between adjacent V-shaped blocks, a single manufactured part may comprise several V-blocks. The compression channel assembly may include a first plate on a first side of the plurality of V-shaped blocks and a second plate on a second opposite side of the plurality of V-shaped blocks and pressure across each compression channel of the plurality of compression channels may be balanced. 
     In the embodiment, wherein the V-shaped blocks may be formed from a single block shaped to form a first wall of a first adjacent compression channel and to form a second wall of a second adjacent compression channel. The first wall may include at least one of a smooth surface or a geometric feature surface and the second wall includes at least one of a smooth surface or a geometric feature surface. The V-shaped blocks may be one or more of machined, casted, molded and printed. 
     In the embodiment, wherein the V-shaped blocks may be formed from a series of plates stacked to form a first wall of a first adjacent compression channel and to form a second wall of a second adjacent compression channel. The first wall may include at least one of a smooth surface or a geometric feature surface and the second wall may include at least one of a smooth surface or a geometric feature surface. The series of plates may have different cross-sections so as to form one or more of a first wall and a second wall having a geometric feature surface. 
     In the embodiment, wherein at least one vane may have a substantially constant cross-sectional area from the outer circumference to the common pressure zone. Wherein the at least one vane may have a variable cross-section area from the outer circumference to the common pressure zone. 
     In the embodiment, wherein the static vane return may further form at least one gas intake port configured to direct gas to the at least one vane. 
     In the embodiment, wherein the static vane return assembly may include at least one pitot duct configured to adjust the fluid level of the annular lake, and/or allow the implementation of a cooling system by removing liquid. Wherein the static vane return assembly may include at least one fluid make up port configured to adjust the fluid level of the annular lake, and/or allow the implementation of a cooling system by adding fluid. Wherein the static vane return assembly may include at least one pressure relief port configured to adjust pressure within the common pressure zone. 
     In the embodiment, wherein the compressor further includes a mounting column adjacent to the static vane return assembly that may be configured to direct gas into the static vane return assembly. 
     While the present disclosure has been illustrated and described herein in terms of several alternatives, it is to be understood that the techniques described herein can have a multitude of additional uses and applications. Accordingly, the disclosure should not be limited to just the particular description, embodiments and various drawing figures contained in this specification that merely illustrate one or more embodiments, alternatives and application of the principles of the disclosure.