Abstract:
Floating bubble jar gas dryer include a container floating in glycol on top of input gas sample pipe. The gas flow pressure regulates the depth of sinking of the floating container in the drying liquid (glycol for water). Small holes at the bottom of the floating container disperse the gas into the liquid where the diffusion process absorbs the moisture from the gas sample.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority of U.S. Provisional Patent Application No. 60/929,355 filed Jun. 22, 2007, which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to gas analysis. More particularly, the present invention relates to drying of a gas for analysis. 
       BACKGROUND OF THE INVENTION 
       [0003]    During the drilling of a well, mud is circulated down hole to carry away drilling cuttings. On the surface the mud is pumped through a gas trap and a gas sample collected. The gas sample collected passes through what is known as a bubble jar where a liquid desiccant, such as a glycol absorbs moisture from the gas sample, thus drying the gas sample before it is sent to a gas analyzer. 
         [0004]    Conventional bubble jars utilize a liquid container and an input tube lowered through the liquid desiccant to the bottom of the liquid container. An output tube is placed at the top of the liquid container. As moisture is absorbed from the gas sample, the level of desiccant rises, and if the bubble jar becomes overfilled, the liquid, absorbed from the sample, may pass through the output tube into the gas analyzer, causing false readings and/or damage to expensive equipment, such as the gas analyzer. 
       SUMMARY OF THE INVENTION 
       [0005]    The invention relates apparatus and method for a floating bubble jar dryer, which includes a container floating in the liquid desiccant (for example glycol) on top of the input gas sample pipe. The gas flow pressure regulates the depth of the float in the drying liquid (for example glycol for water). Small holes at the bottom of the floating container disperse the gas in to the liquid where a diffusion process is absorbing the moisture from the gas sample. 
         [0006]    The bubble jar dryer of the present invention provides increased protection for gas analyzer, with reduced maintenance and monitoring, both in frequency and degree of maintenance and monitoring, and may allow configurations which are smaller and lighter. 
         [0007]    In one aspect, the present invention provides a bubble jar dryer for drying a gas stream, including a first drying section adapted to receive an initial level of liquid desiccant, an inlet adapted to receive the gas stream into the first drying section, a standpipe associated with the inlet, the standpipe adapted to extend above the initial level of liquid desiccant, a floating container movably received on the standpipe, the floating container having an interior and an exterior and an upper section and a lower section, and at least one passage between the interior and the exterior in the lower section, and an inlet adapted to direct the gas stream out of the first drying section, wherein the level of liquid desiccant rises as moisture is absorbed from the gas stream, and the floating container is adapted to at least partially float in proportion to the level of liquid desiccant. 
         [0008]    In a further aspect, the present invention provides a method for drying a gas stream including providing the gas stream from an oil and gas well operation, providing a bubble jar dryer including a first drying section adapted to receive an initial level of liquid desiccant, an inlet adapted to receive the gas stream into the first drying section, a standpipe associated with the inlet, the standpipe adapted to extend above the initial level of liquid desiccant, a floating container moyably received on the standpipe, the floating container having an interior and an exterior and an upper section and a lower section, and at least one passage between the interior and the exterior in the lower section, and an inlet adapted to direct the gas stream out of the first drying section, wherein the level of liquid desiccant rises as moisture is absorbed from the gas stream, and the floating container is adapted to rise in proportion to the level of liquid desiccant, and passing the gas stream through the bubble jar dryer, analyzing the gas stream, and providing a log of gas stream analysis in correlation to the oil and gas well operation. 
         [0009]    Other aspects and features of the present invention will become apparent to those skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Embodiments of the present invention will now be described, by way of example only, with reference to the attached Figures, wherein: 
           [0011]      FIG. 1  is a bubble jar of the present invention (with single drying section); and 
           [0012]      FIG. 2  is a bubble jar of the present invention (with double drying section). 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The present invention provides an apparatus and process for at least partially removing moisture from a gas stream using a buoyant container and liquid desiccant for moisture absorption, for example a glycol to remove water from a gas stream. 
         [0014]    Referring to  FIG. 1 , a bubble jar  10  of the present invention includes a housing  20  having at least a first drying section  30 . Preferably, as shown in  FIG. 2 , the bubble jar  10  also includes a second drying section  40 , downstream of the first drying section  30 . 
         [0015]    The first drying section  30  includes an inlet  50  for receiving the gas to be dried and an outlet  55  for delivering the gas. A level of a liquid desiccant  60 , for example a liquid glycol, for example ethylene glycol, is maintained within the first drying section  30 . A standpipe  70  is operatively associated with the inlet  50  and within a floating container  80 . 
         [0016]    Preferably, the liquid desiccant  60  is a low vapour pressure, non-combustible liquid. 
         [0017]    The floating container  80  has an upper section  90  and a lower section  100  and an interior  110  and an exterior  120 . The upper section  90  forms a vapour space  130 , above the level of the liquid desiccant  60  and the lower section  100  forms a liquid space  140 , below the level of the liquid desiccant  60 . At least one passage  150  extends between the interior  110  and the exterior  120  of the floating container  80 , within the liquid desiccant  60 . Preferably, the at least one passage  150  comprises a plurality of small holes  160 . 
         [0018]    In operation, the bubble jar  10  receives a source of gas to be sampled, for example from a turbine gas trap as described in U.S. Pat. No. 6,389,878 to Zamfes. 
         [0019]    The gas to be sampled enters the bubble jar  10  from the inlet  50 , moisture is removed in at least the first drying section  30  (and preferably moisture is removed in the second drying section  40 ), and the gas is directed to a gas analyzer for analysis, for example to a differential gas detector as described in U.S. Pat. No. 6,276,190 to Zamfes or a gas chromatograph or other gas analyzer. 
         [0020]    Within the first drying section  30 , the gas flows out the standpipe  70  into the floating container  80 . The gas flows through the vapour space  130 , through the liquid space  140 , dispersed through the plurality of small holes  160  into the liquid desiccant  60 , through the level of liquid desiccant  60 , and out of the first drying section  30 , in this preferred case, to the second drying section  40 , where the process is repeated. The inlet  50  and/or the outlet  55  may include an orifice or valve or other control means to control or regulate the flow and/or pressure of the gas. 
         [0021]    The gas analyzer (not shown, downstream of the outlet  55 ) may include a vacuum pump or other suction means to help draw the gas from the bubble jar  10 . 
         [0022]    A filter, media, membrane, mesh, or other device may be installed within the vapour space  130  to reduce the amount of fluid droplets (if any) carried or entrained in flow. Preferably, such a device is a knitted metallic or non-metallic (e.g. plastic) wire mesh entrainment separator  170  situated between the floating container  80  and the outlet  55 . 
         [0023]    A pressure differential across the bubble jar  10  will lift the floating container  80  to a level proportional to its weight and the level of the liquid desiccant  60  in the housing  20  and the pressure differential. If the level of the liquid desiccant  60  reaches the top of the standpipe  70  the floating container  80  will push the excess of liquid out into inlet  50 . This will help improve performance of the bubble jar  10  and help reduce liquid overflow that can plug or otherwise damage the gas analyzer. 
         [0024]    In the preceding description, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the embodiments of the invention. However, it will be apparent to one skilled in the art that these specific details are not required in order to practice the invention. 
         [0025]    The above-described embodiments of the invention are intended to be examples only. Alterations, modifications and variations can be effected to the particular embodiments by those of skill in the art without departing from the scope of the invention, which is defined solely by the claims appended hereto.