Abstract:
Oil which has been heated by use in a gas compressor is cooled by transferring the heat from the oil to gas upstream from the compressor.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     PROVISIONAL PATENT APPLICATION 
     Provisional Patent Application entitled Oil Separator and Cooler was filed on Oct. 26, 1999 and application number of 60/161,425. Applicant was listed as a joint inventor of that invention. Applicant claims benefit of that application. 
    
    
     BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     This invention relates to compressing natural gas for transportation in pipe lines. Managers of compression units have ordinary skill in this art. 
     (2) Description of the Related Art 
     The general practice of transporting natural gas from a well includes compressing the gas from the pressure it has at the well head to a high pressure for transportation to the point of usage. The equipment to perform this task is usually a liquid ring compressor or a screw compressor which are widely used and well known in the art. Characteristic of these compressors is that the compressor has an oil seal. 
     It is necessary in the operation of an oil seal compressor to cool the oil. Some of the oil will mix with the compressed gas at high temperatures. The oil is separated from the compressed gas before the gas enters the pipe line. It is standard practice in compression units to have a mechanical refrigeration unit to cool the seal oil after it has been separated from the compressed gas and before it is reintroduced into the compressor. 
     The refrigeration units add to the capital investment and the operation increase the cost of operating the compression unit. Also it is an additional piece of machinery which requires the normal maintenance and the other operation attention of personnel. 
     SUMMARY OF THE INVENTION 
     (1) Progressive Contribution to the Art 
     According to this invention the hot separated seal oil is fed through a heat exchanger which transfers the heat of the oil into the cold gas coming from the well. The natural gas is cold because of its expansion from the deposit within the earth to the intake of the compressor. 
     The oil is cooled in the exchanger without mechanical machinery. 
     The oil is separated from the gas in part by slinging the oil outward in a centrifugal fashion. 
     The heat transferred from the seal oil to the gas entering the compression increases the gas temperature. This increase in temperature will require more energy to compress the gas to the pipeline pressure. However the ability to avoid the initial cost of the refrigeration equipment and the normal expense necessary for workman to monitor the refrigeration equipment makes the operation advantageous over mechanical refrigeration. There will also be a slight pressure drop of the gas from the well because of the turbulence caused by the gas circulating in the heat exchanger. However; the advantages out weigh this disadvantages also. 
     (2) Objects of this Invention 
     An object of this invention is to simplify the process of cooling seal oil at gas compression units. 
     Another object of this invention is to use the natural resulting low temperature of the gas entering the compressor as a source of cooling for the seal oil used in the compressors. 
     Another object is to simplify the separation of the oil from the compressed gas. 
     Further objects are to achieve the above with devices that are sturdy, compact, durable, simple, safe, efficient, versatile, ecologically compatible, energy conserving, and reliable, yet inexpensive and easy to manufacture, install, operate, and maintain. 
     Other objects are to achieve the above with a method that is rapid, versatile, ecologically compatible, energy conserving, efficient, and inexpensive, and does not require highly skilled people to install, operate, and maintain. 
     The specific nature of the invention, as well as other objects, uses, and advantages thereof, will clearly appear from the following description and from the accompanying drawings, the different views of which are not necessarily scale drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is schematic representation of the invention. 
     FIG. 2 is a representation of an arrangement of the elements of the invention. 
     FIG. 3 is a sectional view taken on line 3—3 of FIG.  2 . 
    
    
     CATALOGUE OF ELEMENTS 
     As an aid to correlating the terms of the claims to the exemplary drawing(s), the following catalog of elements and steps is provided: 
     
       
         
               
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                  12 
                 Inlet 
                 219 
                 Inlet Axis 
               
               
                   
                  14 
                 Separator 
                 220 
                 Top Plate 
               
               
                   
                  16 
                 Heat Exchanger 
                 221 
                 Tangent Line 
               
               
                   
                  18 
                 Lower Reservoir 
                 222 
                 Bottom Plate 
               
               
                   
                  19 
                 Hot oil Conduit 
                 224 
                 Coils 
               
               
                   
                  28 
                 Compressor 
                 230 
                 Separator Inlet Pipe 
               
               
                   
                  30 
                 Compress out pipe 
                 232 
                 Filter 
               
               
                   
                  32 
                 Filter 
                 234 
                 Pipeline 
               
               
                   
                  34 
                 Pipeline 
                 236 
                 Oil Pipe 
               
               
                   
                  36 
                 Oil Pipe 
                 238 
                 Valve 
               
               
                   
                  42 
                 Upper Reservoir 
                 240 
                 Perforated Plate 
               
               
                   
                 210 
                 Tank 
                 242 
                 Upper Reservoir 
               
               
                   
                 214 
                 Separator 
                 244 
                 Oil Drain 
               
               
                   
                 215 
                 Separator Radial Line 
                 246 
                 Concentrate Drain 
               
               
                   
                 216 
                 Heat Exchanger 
                 248 
                 Sight Glass 
               
               
                   
                 218 
                 Collection Reservoir 
               
               
                   
                   
               
             
          
         
       
     
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1 the drawings, it may be seen that gas enters a heat exchanger  16  by pipe  12  from a production well. The gas entering by pipe  12  will be cold. 
     The cold gas will cool hot oil flowing through the heat exchanger. The oil is contained in one or more tubes in the heat exchanger  16 . It is preferred that the heat exchanger has conventional design of a plurality of tubes within a vessel. Heat exchanger of conventional design are readily available. It is preferred that the pressure loss of the gas flowing through the vessel be a minimum. 
     The gas departs from the heat exchanger vessel by outlet pipe  26 . The outlet pipe  26  is also an inlet pipe connected to compressor  28 . The compressor  28  compresses the gas to the is desired pipeline pressure. 
     The compressed gas from the compressor is introduced through pipe  30  into separator  14  where the oil is separated from the gas. The separator  14  may be of conventional design. Such separators are well known and readily available. 
     With the oil separated, the compressed gas flows into distribution pipeline  34  to be distributed. A filter  32  is located between the separator  14  and the distribution pipeline  34  to prevent undesirable substances from entering the pipeline. 
     The oil separated from the gas flows into an upper reservoir  42  through hot oil conduit  19 . There are no obstructions between the separator  14  and upper reservoir  42 . Therefore the oil in the upper reservoir will be under distribution pipeline pressure. Preferably, the upper reservoir  42  is located directly above the heat exchanger  16 . 
     The upper reservoir is connected to the tube or tubes in the heat exchanger  16  without obstruction. Therefore the oil flows freely through the heat exchanger  16  and is caught in lower reservoir  18 . Then the oil is moved through oil pipe  36  to the compressor as is well known to the art. 
     A sight glass (not shown in FIG. 1) is connected from the upper to lower reservoir to indicate the amount of seal oil available. It is important that the compressor unit has an adequate supply of seal oil. It is desirable that there is seal oil in the upper reservoir  42  and is visible in the sight glass. Also an alarm (not shown) will be activated if the supply of oil is reduced to a critical amount. 
     As described above the object of cooling the seal oil by the incoming gas may be achieved by assembling well known elements. However the separator, reservoirs, and heat exchanger may be combined in a single upright tank  210  (FIG.  2 ). 
     The tank  210  is divided by two solid plates into three chambers. The upper chamber contains the separator  214  and the upper reservoir  242 . The middle chamber contains the heat exchanger  216 . The lower chamber is the oil collection reservoir  218 . The three chambers are separated by top plate  220  and by bottom plate  222 . 
     Referring to FIG. 3 it may be seen that the tank  210  and separator  214  is a cylinder having a separator axis. Separator inlet pipe  230  has inlet axis  219 . Separator tangential line  221  is parallel to inlet axis  219  and separator radial line  215  which radiates from the separator axis. The axis  219  is closer to tangential line  221  than to radial line  215 . This configuration results in the oil in the compressed gas to be slung against the cylindrical sides of the separator and to the bottom of the separation chamber  214 . Filter  232  located in the separator  214  below the distribution pipeline  234  helps in preventing oil to go out with the gas in the pipeline  234 . 
     Perforated plate  240  separates the separator  214  from the upper reservoir  242 . 
     The oil will separate from the gas in the separator  214  and drain through the perforated plate  240  to the upper reservoir  242 . The oil from the upper reservoir will exit through the plate  220  into coiled tube  224  and be cool therein. The oil is discharged from the coiled tube  224  thru the bottom plate  222  into the collection reservoir  218 . In the event there is need to drain the oil, oil drain  244  is provided. 
     Condensate drain  246  drains any condensate from the chamber  216 . It will be understood that the condensate drain is connected to a drain pump in as much as the middle chamber  216  might be below atmospheric pressure. 
     A series of sight glasses  248  are connected to the upper chamber  214  above the perforated plate  240  and to the lower chamber  218 . To ensure the compressor  228  does not run low of seal oil, it is desired to keep the level in the upper reservoir  242  at least above half way between the plate  220  and the plate  240 . Although not shown in the drawing there is an automatic cutoff in the event the oil level drops below this level. The cutoff would shut down the compressor  228 . It may be seen that the cold gas from the production well is used to cool the oil from the oil seals of the compressor. The natural refrigeration of the gas is used for this purpose thereby eliminating the need to use mechanical refrigeration. In the event too much seal oil is flowing through oil pipeline  236  the flow may be reduced by valve  238  in the oil pipeline adjacent the collection reservoir. 
     Also by consolidating the different equipment, into tank  210 , the transition may be made by installing the tank  210  with its components. 
     The embodiment shown and described above is only exemplary. I do not claim to have invented all the parts, elements or steps described. Various modifications can be made in the construction, material, arrangement, and operation, and still be within the scope of my invention. 
     The restrictive description and drawings of the specific examples above do not point out what an infringement of this patent would be, but are to point out the advantages and the progressive contribution to the gas compression arts and to enable one skilled in the art to make and use the invention. The limits of the invention and the bounds of the patent protection are measured by and defined in the following claims.