Abstract:
A method for cleaning a pipline by providing a filter or a number of filters adapted to reside in the pig launcher of the pipeline. The filters can be used to remove debris and impurities from the fluid flowing in the pipeline during a pigging operation. Alternatively, the filters may be retained in the pig launcher for extended periods of time.

Description:
BACKGROUND OF THE INVENTION 
     Pipelines can cover great distances in transporting a variety of products, primarily petroleum fluids such as natural gas, crude oil and refined products. The pipelines can have build-ups of impurities, such as corrosion, and foreign particles, such as dirt, on the inside of the pipeline that can hamper transmission and contaminates the product transported in the pipeline. Also, with raw materials transported on pipelines there can be naturally occurring impurities that occur and impede the transmission of the fluids. Also, increased power costs are incurred when fluid with impurities is transported through a pipeline. 
     There are different approaches to cleaning the inside of the pipeline while not disrupting the transmission of the fluids. One method is the use of a short cylindrical body known as a pipeline pig that has on outside diameter that fits inside the pipe. The outer surface of the pig scrapes off the build up of contaminates on the inside of the pipeline and the contaminates are carried with the fluid through the pipeline. The pigs are so commonly used that modifications in the pipelines called pig launchers and pig receiver units are built into the pipelines often every 50 to 70 miles or so. The pig launcher and receiver units are above ground and easily accessible while the pipeline may or may not be above ground. The launcher and receiver units have piping arrangements so that the pig enters the pipeline without disrupting the fluid flow and can be retrieved, cleaned and redeployed. 
     The contaminates in the fluid can be kept in suspension and filtered at the end of the pipeline or are carried in the fluid and can cause contamination problems at a plant receiving the product. Dirt in the fluid can clog trays in the processing of a petrochemical product. In order to remove the contaminates in the transport process, external high pressure filter units are used and the fluid is diverted from the pipeline for filtering. This process is expensive and requires special filter units along the pipeline to be assured of clean fluid transport. 
     SUMMARY OF THE INVENTION 
     This invention is a method of filtering the fluid in a pipeline without disrupting the fluid flow and using existing pig launchers for filter apparatus. The modification of the existing pipeline structure is minimal and required to external high pressure filtering apparatus. 
     The method includes introducing a filter into the pig Launcher or receiver. The filters are sized to fit inside the launcher body and any adjacent pipe. If needed, an extension known as spool can be attached to the launcher body to accommodate the additional filters. The fluid from the pipeline enters the launcher body that contains the filters. The filter is secured in the launcher body so it will remain in place during the filtering process. Typically, the filters used in this invention are outside/in filters so that the fluid passes through the filter media and enters a fluid permeable central core. The filter media traps the impurities and the filtered fluid passes through the central core through a conduit from the central core to resume travel through the pipeline. 
     More than one filter may be used. Typically more than one filter is used and an assembly is made of several filters in a filter cartridge carrier assembly. The filters are connected with a pressure tight connection from the core exiting the filter and the core entering the adjacent filter in a series along the length of the launcher. The terminal filter of cartridge carrier assembly adjacent to the downstream pipeline entrance introduces the filtered fluid from the central core to the pipeline. The filter at the opposite end of the filter cartridge carrier assembly has a cap on the core opening that is not connected to the adjacent filter. As an option, a rupture plate can be placed on the end of the filter instead of a cap. This allows for the plate to rupture in case the filters become clogged and the differential pressure build up to a certain level, allowing the unfiltered fluid to pass through the core and the pipeline. 
     Another multiple filter arrangement includes mounting multiple filters in a series such that more than one filter fits into the inner diameter of the launcher body or the pipe associated with the launcher body. The cores of each filter are connected in a parallel fashion along the horizontal length of the body holding the filters. At the end of the parallel series there is a collector that attached to the core of each of the terminal filters and passes the fluid to the pipeline. 
     The filtering process can take place before or after a pig has traveled through the pipeline to dislodge impurities. Once the filtering operation has been accomplished, the filters can be removed from the launcher body and a pig can be redeployed. Or the filters can be placed in the launcher and used without the pigging operation. The filters can be deployed temporarily for a short period of time during the pipeline cleaning process using a pig to filter out the impurities dislodged during the cleaning process or for longer periods of time regardless of whether a pig is used. 
     To utilize the new method, the only modification to the pipeline is the insertion of a sump plate in a flange downstream to the pig launcher. The sump plate or equivalent structure is adapted to receive the filtered fluid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a pig receiver and the by-pass piping to the pig launcher which is cut away to show one embodiment of the filters. 
         FIG. 2  shows a pig receiver and the by-pass piping to the pig launcher which is cut away to show an embodiment of the filters. 
         FIG. 3  is a detail of the filter cartridge carrier assembly with centralizers. 
         FIG. 4  is a detail of a multiple filter cartridge carrier assembly with centralizers adapted for use with the arrangement shown. 
         FIG. 5  is a perspective view of the terminal centralizer and fluid collector for the multiple cartridge assembly of FIG.  4 . 
         FIGS. 6   a ,  6   b ,  6   c  and  6   d  show the insertion of a filter into the pig launcher. 
         FIG. 7  is a perspective view of the installation of the sump plate in the flange. 
         FIG. 8  is a view of the sump plate installed in the flange. 
         FIG. 9  is a schematic view of the placement of a pig launcher and receiver above ground relative to a buried pipe. 
         FIG. 10  is a more detailed description of the pig launcher above ground to be deployed with a filter. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The arrangement in  FIG. 1  illustrates the features of practicing the method of the invention. Fluid is passing through the pipeline  10 . A pig device  12 , which is generally a short cylindrical body, is shown passing through the pipeline. Generally, the outer diameter of the pig is sized to fig snuggly inside the pipeline. The pig  12  is carried by the fluid pressure through the pipeline  10  to remove dirt, debris and corrosion, and ultimately ends its travel through the pipeline  10  at pig receiver  14 . The pig receiver  14  is generally a cylindrical body at the end of the pipeline  10  that terminates with a pig receiver opener  16  that can be swung open to remove the pig once it completes its travel through the pipeline. The normal vent valves are shown but not numbered on the pipeline and pig receiver  14 . 
     There is a bypass line  18  that connects the pig receiver  14  to the pig launcher body  20 . The pig launcher body  20  is shown with the standard vent valves that are not numbered. The pig launcher body  20  is cylindrical and has the pig launcher opener  22  at one end. The other end of the pig launcher body is attached to the pipeline  24 , which resumes carrying the fluid downstream to the destination. In  FIG. 1 , the pig launcher body is shown cut away with a filter cartridge carrier assembly generally indicated at  26 . The filter assembly  26  is composed of three filters  28   a ,  28   b  and  28   c  that are arranged in a linear fashion inside the pig launcher body  20 . Filter  28   a  is the terminal filter next to the pig launcher opener  22  and has a cap  30  on the terminal end of the outlet of the filter. The cap  30  may be replaced with a rupture plate that will break when the differential pressure exceeds a predetermined level. The filters shown in  FIG. 1  are outside/in filters with filter media surrounding a central core that is fluid permeable. The central core is connected to an inlet and outlet of the filter that is not fluid permeable. 
     Filter  28   a  is held in place in the pig launcher body in part by filter centralizer body  32   a . The filter centralizer body has legs extending from a generally circular disc such that the legs are sized to hold the filter in the pig launcher body during the filtering process. The legs do not have to have a close tolerance to the inside of the pig launcher body, but provide support and stability for the filters. The filter centralizers also have a central opening sized to receive the filter inlet or outlet as shown in more detail in FIG.  3 . The filter centralizers also have openings to receive tie rods on their outer perimeter for connecting the multiple filter centralizers. Filter  28   b  is connected to filter  28   a  with filter centralizer  32   b . Tie rods connecting filter stabilizer  32   a  to  32   b  in  FIG. 1  are shown at  34   a  and  34   b . Similarly, tie rods  34   c ,  34   d ,  34   e  and  34   f  connect the filter centralizers  32   b ,  32   c  and  32   d  in the same manner. The outlet of filter  28   a  is received into the central opening of filter centralizer  32   b , while the inlet to filter  28   b  is received on the other end of the opening, thereby providing fluid communication between the filters. Filter  28   b  outlet and filter  28   c  inlet are similarly connected with filter centralizer  32   c  in a pressure tight manner. 
       FIG. 1  shows three filters in the filter cartridge assembly  26 . However, as shown elsewhere, as many filters as necessary can be used, and the arrangement in  FIG. 1  is for illustrative purposes. The outlet of filter  28   c  is inserted into the central opening of filter centralizer  32   d . The opposite end of the opening of  32   d  is connected to a tube conduit  36 , which extends from the outlet of the filters and carries the filtered fluid. The tube conduit  36  also has centralizers  38   a  and  38   b  to support it inside the extension of the pig launcher, which as shown in  FIG. 1  may have a smaller diameter than the pig launcher body. The centralizers are sized to hold the conduit tube in place. The terminal end of the conduit tube going downstream is tapered and fitted with O-rings to slide into sump plate  40  as shown in FIG.  1 . 
     Sump plate  40  is held between flanges  41   a  and  41   b  and is the only modification to the pipeline that needs to be made to practice the method of this invention. Sump plate  40  has a smaller diameter than the flange and pipeline opening. The tube conduit  36  is adapted to fit tightly in the sump plate because it has a tapered end  42  that can be guided into the sump plate  40 . There is a collar  44  at the end of the taper to stop the travel of the conduit tube  36  into the sump plate  40 . The sump plate  40  is fitted with O-rings shown at  46   a  and  46   b . The sump plate arrangement is a convenient way to secure the flow of the filtered fluid to the downstream pipeline  48 . However, other means known to those skilled in the art can be used to practice the method of this invention. 
       FIG. 2  is an embodiment of the invention with additional filters of smaller relative diameters shown. For ease of reference, the same numerals will be used for the corresponding parts, and new numerals will be used for the additional filters. There arc three additional filters shown as  50   a ,  50   b  and  50   c  that are shorter and smaller in diameter relative to filters  28   a ,  28   b  and  28   c , illustrating the feature of the method that any size or number of filters may be used. The additional filters are connected in a linear manner in the pig launcher body  20  and the extension of that body that has a smaller diameter by using filter centralizers  54   a ,  54   b  and  54   c  of the same construction as previously described for FIG.  1 . Similarly, the tie rods  52   a ,  52   b ,  52   c ,  52   d ,  52   e  and  52   f  connect the central stabilizers. 
     Filter  50   c  is the terminal downstream filter in FIG.  2 . The outlet of filter  50   c  is connected through the central opening of the stabilizer. 
       FIG. 3  is a detailed depiction of a portion of an embodiment of the filter cartridge carrier assembly  26  as shown in  FIGS. 1 and 2 . The filter centralizers are shown in greater detail with the leg extensions numbered  102   a  and  102   b  on filter centralizer  100   a . The legs terminate in a flat, slightly rounded foot that can contact the inside of the pig launcher or receiver body holding the filter cartridge carrier assembly so that it is held safely within the body during fluid flow. The filter centralizers have tubular members extending through the central opening on either side of the filter centralizer. As the centralizers are fastened to the filters, they perform the dual purpose of maintaining the filter cartridge carrier assembly in the pig launcher or receiver body and attaching the filters to allow flow of pressurized fluid through the central cores of the attached filters in the assembly. The filter centralizer tubes fit tightly on the filter inlets and outlets which are shown, and are provided with O-rings as shown on filter  108  in FIG.  3 . Any other means of providing a pressure tight fit may be used. In  FIG. 3 , the filter  108  has an inlet tube that is shown with the O-ring neck that fits inside the filter centralizer tube  104   a . The filters are joined with the filter centralizers between each filter as shown in detail in FIG.  3 . 
     The filter centralizer bodies can also be provided with openings on their perimeter to receive tie rods to stabilize the filter cartridge assembly. As shown in  FIG. 3 , filter centralizer  100   a  has three pair of openings to receive tie rods that connect each adjacent filter stabilizer. Tie rods  110   a ,  110   b  and  110   c  connect filter centralizers  100   a  and  100   b  with three tie rods surrounding the outside of filter  108 . The tie rods shown are threaded and extend the length of the filter  108  and through the filter centralizers  100   a  and  100   b . The tie rods are fastened by a nut to secure the end of the tie rod that extends through the body of each of the filter centralizers  100   a  and  100   b . The tie rods are not essential to the invention. Any method or apparatus to stabilize the filters can be used and are known to those skilled in the art. 
     To further illustrate the invention,  FIG. 4  is a detailed drawing of a filter cartridge carrier assembly that holds more than one filter in parallel. The figure shows three filters in parallel that are connected with filter centralizers in a similar fashion to FIG.  3 . The parallel filter centralizer  120  has three openings, rather than one central opening, through which tubes extend on either side to connect with filter inlets and outlets. The parallel filter cartridge assembly can be used when the configuration of the pig launcher or receiver is sized to accompany this arrangement or when the need requires optimizing the number of fibers used. The parallel filter stabilizer body  120  is shown with the tubes  122   a ,  122   b  and  122   c  extending from the body of the stabilizer. These tubes fit tightly around the inlets and outlets of the inflow filters  124   a ,  124   b  and  124   c , which are in parallel flow. Then the tubes connect to outflow filters  124   a ,  124   b  and  124   c , respectively. The tie rod stabilizer arrangement is also shown in FIG.  4  and functions in the same manner as previously described. 
     At the terminal end of the filter cartridge for the parallel filter arrangement, a specialized filter centralizer  130  may be used as shown in FIG.  5 . The centralizer has three tubes  132   a ,  132   b  and  132   c  extending from one end of the centralizer that feed the filtered fluid from the terminal filters into a conical body  134  extending from the centralizer that collects the filtered fluid from the terminal three filters in the parallel arrangement as shown in FIG.  4 . The conical body  134  tapers to a round neck  136  that extends from the conical body and is fitted with grooves for O-rings so that it can connect with tube conduit and the fluid can resume travel through the pipeline. The arrangement shown in  FIGS. 1 and 2  with the tapered conduit tube  36  with the tapered end  42  can be used. However, any type of pressure tight connectors may be used. 
       FIGS. 6A ,  6 B and  6 D illustrate the ease in preparing the filter assembly cartridge and loading into a pig launcher. For ease of reference, the same numerals from  FIGS. 1 and 2  are used. The filter flow to the pig launcher is halted, and the pig launcher opener  22  is swung to the open position to allow for entry of the filter cartridge assembly. The tube conduit with tapered end  42 , with the collar securing the O-rings  46   a  and  46   b , enter the pig launcher receiver body  14  first. The same arrangement of tube conduit centralizers  38   a  and  38   b  are used. The number of filters used to practice the invention depends on the desired filtration and the size of the pig launcher. If the pig launcher is not the desired length and needs to be longer to accommodate more filters, a cylindrical extension may be connected to the opening end of the pig launcher. These parts are known as “spools” and are connected to the end of the pig launcher with flange and gasket connections. 
     Any type of filter may be used depending on the fluid being transported and the impurities that need removal. The filters are typically cylindrical in shape. The filters illustrated in the figures are PLATINUM™ Series filters made by Filtration Technologies Corporation, and are fully described in U.S. Pat. No. 5,824,232, which patent is fully incorporated by reference herein. Filter  28   c  is stabbed into the tube in filter centralizer  32   d  in a pressure tight connection to provide communication of the filtered fluid from the core of filter  38   c  to the conduit tube  36 . The centralizers are used to guide the filters in and out of the pig launcher body and/or the pipe holding the filters. The centralizers are sized to fit comfortably inside the pipe and support the filters. As shown in  FIG. 6B , the filters are added to the assembly by use of a filter centralizer  32   c  to connect the filter  28   b  so that the cores of the filters communicate in a pressure tight connection. The tube conduit  36  travels through the pig launcher body. The number of filters and the length of the conduit tube are sized so that the tapered end  42  of conduit  36  will extend and seal into the sump plate as shown in  FIGS. 1 and 2 . 
       FIG. 6C  shows the connection of the three filters  28   a ,  28   b  and  28   c  and their introduction into the pig launcher  14 . In  FIG. 6D  the pig launcher opener  22  is swung to the closed position, and fluid can be introduced for filtration. The fluid enters from bypass line  18  as shown in  FIGS. 1 and 2  into the pig launcher with the filter assembly secured inside. The fluid enters from the outside of the filters under pressure and through the selected filter media. The fluid then passes into the cores of each of the filters  28   a ,  28   b  and  28   c . The filters are connected in the manner described so that the cores communicate the filtered fluid and passes it through the cores to the tube conduit  36 . The filter fluid then resumes flow through the pipeline. 
     Typically, one modification of the pipeline is required to accommodate the invention. The tube conduit&#39;s tapered end  42  is secured in a sump plate  40  as shown in  FIGS. 1 and 2 . The sump plate  40  is placed at a flanged connection typically already present in the pipeline.  FIGS. 7 and 8  show a detail of sump plate  40  that is inserted between flanges  41   a  and  41   b  and secured as shown in FIG.  8 . The connection is pressure tight, and gaskets (not shown) of other means to provide a pressure tight connection can be made as commonly known to those skilled in the art. 
       FIG. 9  is a schematic drawing of an underground pipeline with a pig launcher  200  and a pig receiver  202 . The pipeline  204  is underground between the pig launcher and receiver. The various bypass lines are not shown. This drawing illustrates the case of using the method of the present invention to filter fluid in the pipeline without hauling a separate high pressure filtration to a site and having the installation difficulties using a separate filtration unit. The drawing also shows a pig launcher receiver  202  that can be used to house a filter cartridge carrier assembly and practice another variation of the method of this invention. The filtration method can be employed using the pig receiver to hold the filter cartridge assembly. This is especially useful at the end of the pipeline where there is no pig launcher. The filters are placed in the receiver in the same manner as described herein. Fluid flow would be directed to the outside of the filters, and the filtered fluid would be collected in the filter cores. The filtered fluid would then be collected and transferred to the processing plant or other line at the end of the pipeline. 
       FIG. 10  is a depiction of an above ground pig launcher associated with a pipeline. The pig launcher  210  is shown with a pig launcher opener  212  in the closed position. A holder  214  is shown with a filter cartridge carrier assembly  216  placed adjacent to the pig launcher. The filter cartridge carrier assembly  216  can be easily accessed to place into the pig launcher when needed. Bypass line  218  is also shown. Flange connection  220  that would be modified to include the sump plate used with this invention is also shown. The other piping and valves are those typical to this type of installation. 
     Other embodiments are within the scope of the following claims.