Patent Abstract:
A system for recovering and recycling otherwise vented or flared volatile and non-volatile reactive organic materials from pipeline and plant operations associated with oil and gas recovery, refining and petrochemical manufacture, processing and transportation includes a means to remove and store volatile hydrocarbons for a portion of a system or pipeline.

Full Description:
This application claims the benefit of U.S. Provisional Patent Application No. 60/755,929 filed Jan. 3, 2006. 

   FIELD OF THE INVENTION 
   The invention relates generally to reducing emissions of volatile compounds. More particularly, the invention is a method for reducing emissions of highly reactive volatile organic compounds from pipeline operations associated with oil and gas recovery, production, refining, and petrochemical manufacture, processing, and transportation. 
   BACKGROUND OF THE INVENTION 
   Many oil, gas, and petrochemical pipeline operations, including pigging, swabbing, changes of meter parts, pipeline inspection maintenance (PIM), and the like, produce emissions of volatile organic compounds in associated venting or flaring operations. Pipeline operations also generally cover considerable distances, making it difficult and expensive to deal with these types of emissions. 
   Over the past few years, there has been more and more regulation of emissions of contaminants into the air. The passage of the Clean Air Act Amendments of 1990, the Kyoto Accord, and other regulations have set the stage for the reduction of air emissions worldwide. Reduction of air emissions is a priority for both countries and companies. 
   Air emissions in the United States are regulated by the Environmental Protection Agency (EPA). The EPA is the agency directly responsible for regulating air emissions in many states; however, in certain states the responsibility for regulatory compliance has been delegated to state agencies, e.g., in California, Texas, Louisiana, and others. Each state that has the responsibility for regulatory compliance must submit a State Implementation Plan (SIP) to the EPA for approval. The goal of the SIP is to implement federal standards in a manner that reflects the priorities and conditions of air emissions within the state. The SIP can be more stringent than the federal standards but not less so. 
   The Clean Air Act Amendments of 1990, and earlier legislation, divide a state or region into “attainment” and “non-attainment” areas. The “attainment” areas are those geographic areas considered capable of meeting federal standards for air quality. The “non-attainment” areas are those geographic areas that cannot meet or attain air quality standards. Those that emit pollutants into the air in “non-attainment” areas have to implement more stringent performance standards to reduce emissions. These more stringent standards extend to businesses in certain “SIC” code categories and can even extend to the general public for automobiles to meet certain emissions standards. 
   “Non-attainment” areas generally have more stringent criteria for certain air emissions. These criteria can include reduced allowable emissions of the oxides of nitrogen (NOx) or reduced allowable emissions of smog precursors such as VHAP&#39;s or HRVOC&#39;s. A “VHAP” is an acronym/abbreviation for ‘Very Hazardous Air Pollutant’ and HRVOC is an acronym/abbreviation for ‘Highly Reactive Volatile Organic Compound’. Since VHAP&#39;s and HRVOC&#39;s are smog precursors, recent SIP proposals to the EPA have stated that smog, a criteria pollutant, may be limited by controlling the amount of VHAP&#39;s and HRVOC&#39;s that are emitted to the atmosphere. Indeed, many regulated areas are beginning to place emissions “caps” on identified atmospheric pollutants, a “cap” meaning that there is a certain amount that a business entity can emit without an economic penalty and when the “cap” is exceeded then economic penalties are incurred. 
   With the introduction of the allowable emission “cap”, long-standing practices in the production, manufacturing, refining, transportation, and distribution of chemical and refined products must be examined. Recent SIP documents have resulted in regulations for HRVOC materials that define, limit, and establish the basis for documenting HRVOC emissions. HRVOC emissions events can be categorized as any of the following activities: a) venting HRVOC material to the atmosphere; b) flaring HRVOC material to the atmosphere; and c) fugitive emissions from equipment. 
   Venting and flaring of hydrocarbons has been done since the earliest days of oil and gas production. Early oil production had excess natural gas co-produced with the oil. Since there was no market for this co-produced gas, the gas was vented or flared. Old stories abound that the sky was lighted so brightly at night by flared gas that one could read a newspaper virtually anywhere oil was being produced. 
   As refining and petrochemical industries began to process “deeper into the barrel”, flaring and venting continued to play a primary role in plant safety. Pressure relief, with the accompanying venting and flaring, was then and continues to be one of the primary methods of assuring safety in refining and petrochemical facilities. Venting and flaring have long been accepted and unquestioned practices in the refining and chemical industries. 
   Over the past several years there has been increased environmental awareness that has resulted in laws and regulations implementing those laws to promote “cleaner” air and reduced earth-warming gases. Man has finally achieved a level of activity in emissions to the atmosphere and energy consumption that the earth&#39;s atmosphere is being profoundly affected. Regulatory response has been ever more stringent regulation of emissions to the atmosphere of “criteria” pollutants, including oxides of nitrogen, oxides of sulfur, earth-warming gases, carbon dioxide, volatile organic compounds, volatile hazardous air pollutants, and highly reactive volatile organic compounds. It should be noted that regulations generally do not eliminate certain activities, but rather promote regulatory “complexities” in the form of more stringent specifications and reporting requirements that create incentives to “do things a different way”. This is the case with both flaring and venting operations in industrial applications. 
   Accordingly, there exists a need for a method for reducing emissions of volatile organic compounds in pipeline and other operations and that is the subject of the present invention. 
   SUMMARY OF THE INVENTION 
   The present invention provides a system of recovering and recycling the otherwise vented or flared volatile and non-volatile reactive organic materials from pipeline and plant operations associated with oil and gas recovery, refining and petrochemical manufacture, processing and transportation. 
   Emissions of organic compounds that include the HAP, VHAP, and HRVOC compounds from such operations have in the past been disposed of by venting. To avoid putting such “hazardous air pollutants” (HAP) and “very hazardous air pollutants” (VHAP) into the atmosphere, such emissions are typically flared, that is, they are disposed of by burning. This invention/process provides an alternative to flaring and recycles products to a useful purpose rather than sending such products to the atmosphere. 
   There are many operations in which this invention is applicable. Typically, these operations are those in which flaring is performed during some operational procedure. The invention is applicable in virtually every instance that requires equipment to be “blown down”, including pipeline and equipment maintenance and startup and shutdown operations and filter and flow meter servicing. The invention is specifically applicable in any pipeline and plant operations that include a system of piping and valves adapted to be opened and closed without disturbing product flow in the main system, for example, to insert or remove pipeline pigs or swabs. 
   The invention comprises, in part, a set of pipes, valves, pumps, and associated equipment to connect operatively with the drain valves and blowdown valves that are typically associated with a pig trap or other isolation vessel associated with a maintenance or service operation that has a set of blocking valves and the necessary drainage and blowdown valves. Through these connections, organic compounds that are isolated between the blocking valves are caused to flow into a product recovery tank that may be located on a truck bed or some other suitable portable carrying means. 
   Once the products have been essentially completely recovered from the pig trap or other isolation vessel, the entire recovery system may be purged of organic materials so that it is safe to close and disconnect. 
   It should be noted that the initial flow from the pig trap or isolation vessel will ordinarily be due to the existing pressure as well as product volatility of some (but not all) of the products being handled by the main system. Thereafter, nitrogen or any other appropriate purging gas (even methane or natural gas could also be used to advantage in some processes), may be employed to complete the product recovery phase. 
   The final part of the product recovery phase is typically performed under pressure. First, a “purging” phase is conducted, to “push” the organic materials through the collection system with a suitable gas, such as nitrogen. Thereafter, where appropriate, a suitable vacuum may be applied to help vaporize and remove the remaining hydrocarbons. This is especially helpful with volatile organic compounds, the preferred target of this process. On materials like crude oil with considerably lower vapor pressures, applying a vacuum accomplishes very little. However, on materials such as propylene, butenes (alkenes), and the lighter alkanes (defined as having eight or fewer carbon atoms), which products tend to vaporize relatively easily, a vacuum is advantageously applied. The equipment used in the process of the invention is adapted to handle both positive and negative pressures. 
   The method of the invention basically involves:
     1) Connecting a product recovery tank and negative pressure generator apparatus to a pipeline, under appropriate safety precautions, at a location where a pipeline operation is underway or planned;   2) Shutting down product flow;   3) Collecting at such location residual product that has been isolated at such location as a result of the shut down into the product recovery tank;   4) Recovering the collected product, using negative pressure where necessary, by purging the residual product from the product recovery tank to assure essentially complete recovery;   5) Either, a) returning the recovered product to the pipeline or b) recycling the product as a useful product at a different location; and   6) Disconnecting the product recovery tank and making sure everything is again in the normal operating mode and safe to resume normal operations.   

   The method of the invention requires at least one trained operator and a portable unit that may be affixed on the bed of a truck but can also be transported to the appropriate location by other mobile transport means, as will be understood by those skilled in this art. The method sometimes also requires the cooperation of those employed at the specific pipeline operation at which the method is to take place. 
   The portable unit used in this invention method may comprise:
     1. A product recovery vessel, which is typically a tank suitably sized to collect all residual hydrocarbon that has been isolated and collected at the operation shut down site;   2. The necessary flexible piping and associated hardware to connect the product recovery vessel to the pipeline portion or collection vessel in which the residual hydrocarbon has been isolated;   3. Purging means, adapted to assure that essentially all residual hydrocarbon that has been collected is removed from the pipeline portion or vessel in which it has been collected; and   4. Recycling means, adapted to return the hydrocarbon product that has been collected in the product recovery vessel to the pipeline or plant facility, or to empty the product recovery vessel at another location.   

   The purging means and the recycling means used as described above may be powered by an internal combustion engine that is no larger than that typically found on motor vehicles, specifically automobiles. The engine, suitably sized to accomplish the desired purging and pumping operations, is adapted to generate the determined negative or positive pressure by any means suitable and well within the skill of those having ordinary skill in this art. It will also be noted and understood by those skilled in this art that the engine may also be adapted to run on the particular volatile hydrocarbon that is being recovered, or a mixture of such a hydrocarbon mixed with a suitable natural gas, gasoline, or diesel fuel. 
   The recovery of the products and the subsequent combustion/oxidation of the vapors of the VOC&#39;s, further reduces the “potential to emit”. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a piping diagram illustrating a pig trap arrangement in a typical pipeline system. 
       FIG. 2  is a piping diagram illustrating the functional parts of one embodiment of a system according to the present invention and how they are interconnected. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Advantageously, the present invention provides for the reduction of venting and flaring in pipeline operations associated with oil and gas production and petrochemical manufacturing and refining. This is accomplished by operating several systems together to accomplish the stated objectives of: i) reducing venting and flaring to the atmosphere; ii) maximizing product recovery; iii) documenting the operation to assure regulatory agencies that objectives were accomplished. 
   An example is used below of a “pigging” operation, where a “pig” or “swab” is received into a pipeline “pig trap”. A pig trap is a system of piping and valves constructed to receive a “pig” or “swab” and is generally arranged as shown in  FIG. 1 . While the example shows a pertinent application of the invention, the example is only one of many areas of application of the invention. 
   Description of Normal Pig Trap Operation 
   In normal operation of a pipeline  100 , a trap bypass valve  102  is open and a trap valve  101  and a trap jump over valve  103  are closed. The trap valve  101  and the trap jump over valve  103  serve to isolate a pig trap  107 . The system also includes a test valve  108  up to 1500 feet upstream of the pig trap  107 . 
   When the pigging operation is initiated, the trap valve  101  and the trap jump over valve  103  are both opened and the trap bypass valve  102  is closed. Once a pig (not shown) is captured within the pig trap  107 , the trap bypass valve  102  is opened and the trap valve  101  and the jump over valve  103  are closed. This action isolates the pig in the pig trap. Before a trap closure  106  can be opened and the pig removed from the pipeline system, a drain valve  105  is opened for the isolated pipeline product material to be vented or flared to the atmosphere through a discharge line  110 . Once the drain valve  105  is opened, the trap can be purged by attaching a nitrogen connection to a blow down valve  104 . The nitrogen purge then purges the excess material from the pig trap through the drain valve  105 . Once the pig trap has been purged, the trap closure  106  can be opened to remove the pig. 
   When the trap closure  106  is opened, in many cases, personnel working in the area must be in personnel protective equipment (PPE) that may include protective clothing or special breathing apparatus to insure the health and safety of the personnel in the area. Indeed, in many cases, liquid is trapped behind the pig and this liquid is spilled on the ground or a container on the ground and must be placed in drums later. This trapped liquid is easily handled by placing a “T-handle” (like a pipeline location probe) in the trap  107  with the “T-handle” butting up to the closure  106  and the length of the “T-handle” that extends from the pig trap closure flange past the jump over piping connection including jump over valve  103 . This enables the pig to end its journey in the pig trap slightly higher and allowing trapped liquids to pass into the drain. This helps assure that the pig trap is properly emptied in the purge procedure and makes a safer entry of the pig into the pig trap with a minimum of trapped hydrocarbons. 
   Description of Pig Trap Operation and the Invention 
   The method of the present invention eliminates the waste of the fluid that would otherwise result from the operation of the prior art as just described. The method of this invention may define different operating modes. These modes can be described as follows:
     1) Connecting the invention and taking safety precautions;   2) Product Recovery Mode;   3) Product purge mode;   4) a) Product Return mode where the product is returned to the pipeline, or
       b) product recycle mode where the product is recycled as a useful product at a different location; and   
       5) Disconnecting and making sure everything is again in the normal operating mode and safe to resume normal operations.   

   As previously described, in normal pipeline operation, the trap bypass valve  102  is open and the trap valve  101  and the trap jump over valve  103  are closed. When the pigging operation is initiated the trap valve  101  and the trap jump over valve  103  are both opened and the trap bypass valve  102  is closed. Once the pig has been received in the pig trap  107 , the trap bypass valve  102  is opened and the trap valve  101  and the jump over valve  103  are closed. This action isolates the pig in the pig trap along with remaining product. The invention is ready to be attached to the components in the pig trap. 
   Connecting the Invention and Taking Safety Precautions 
   The purpose of the following safety precautions section is to set up the invention, preferably at a shop prior to moving the invention to a work site, and then to connect the invention properly to operating equipment. This section provides a checklist and a description of all of the valve positions and equipment states that should exist for the invention when operations are initiated. 
   Once the pig is isolated in the pig trap as described above, the following should be accomplished: 
   a) A responsible operations person should check the trap valve  101  and the jump over valve  103  to make sure both valves are closed. If either of the valves is motor operated, the valve operator should be placed in the manual mode so that the valve cannot be remotely operated. Both valves are then appropriately “locked out and tagged out” for the duration of the time the pig trap (or other equipment) is being maintained. For the duration of the time the invention is in use, the invention operator should have the “lock out tag out” keys that lock the valves  101  and  103 .
 
b) Once the trap valve and jump over valves have been secured, the protecting blind flanges or bull plugs should be removed from the drain valve  105  and a blow down valve  104 . Once the blinds or plugs are removed, a flexible hose or line is attached to the pipe  110  at the drain valve  105  to connect the system of the present invention at a system block valve  200  as shown in  FIG. 2  of the drawings. Another appropriate connection is also made that joins the blow down valve  104  to a purge system nitrogen connection  380  ( FIG. 2 ) should be installed. To complete the system lineup, a recycle connection is coupled between a blowdown valve  109  and a recycle cutoff valve  420 , shown also in  FIG. 2 .
 
c) All systems, motors and test equipment should be checked before transporting the system of  FIG. 2  of this invention from the shop and the quantity of nitrogen (illustrated as nitrogen bottles  350  in  FIG. 2 ) should be checked to make sure there is enough nitrogen to perform the planned operations in the field. Once the pig trap and other field equipment are connected to the invention, motors  540  and  560 , generator and test equipment  650 , central processing unit  660 , and engine emissions analyzer  670  should be started and time allowed for the motors and test equipment to warm up and begin to operate properly. The equipment may include a central processing unit  660 , which is coupled to the test equipment with wires or wirelessly. The central processing unit  660  also communicates with various points in the system through a communications bus  661 , while the connections of the bus  661  are omitted here for simplicity.
 
d) While the motors and test equipment are warming up, a nitrogen blanket should be established on a product recovery vessel  240  by opening a nitrogen valve  340  and a nitrogen pressure regulator  320  that provides nitrogen to the product recovery tank  240 . The product recovery tank  240  may include an internal vaporization exchanger  360  inside the product recovery tank  240  to vaporize liquid nitrogen and thereby cool higher vapor pressure products in the product recovery tank  240 , such as ethylene, for example.
 
e) Next, the product recovery tank regulator  320  should be adjusted so that the regulator  320  will hold roughly 100 pounds per square inch gauge back pressure, depending on the product to be recovered, before relieving to a purge system liquid knockout drum  440 . This regulator may require adjustment to adjust the back pressure to be higher or lower depending upon the ambient conditions and the product material being recovered.
 
f) A purge system block valve  430  should be closed and “lock out-tag out” procedures should be used to make sure this valve is closed until needed in the purging process.
 
g) A product recovery block valve  210  should be in the closed position but not locked out and a product recovery tank block valve  230  should be in the open position. A flow meter  227  should be reset to zero and a reading of the total flow noted. A flow reversal valve  223  should be in the closed position.
 
h) All connections between the invention and the pipeline operating equipment of  FIG. 1  should be rechecked. The pig trap drain valve  105  should be checked to make sure that a secure connection exists to the system block valve  200  and that the pig trap blowdown valve  104  is connected to the nitrogen purge block valve  380 .
 
i) Other valve positions and component states in the system are listed by number in the table below:
 
                                             TABLE 1                   Component State/Position at the Start of Recovery Operations            Component #   State   Component #   State   Component #   State               400   Open (if 420   420   Closed/Locked   390   Closed           is locked)       370   Closed   330   Open   310   Open       270   Open/Locked   280   Sealed   490   Closed       470   Closed   450   Closed   510   Open       530   Open   630   Open   610   Open       410   Off   540   On   560   On       560   On @ 550   670   On @ 570   660   On @                           670                    
Operating in the Product Recovery Mode
 
   The purpose of the product recovery mode is to recover as much of the isolated product as possible so that the isolated product is not vented to the atmosphere; it is not flared to the atmosphere; and it can be returned to the pipeline or plant facility or the product can be carried to an offsite location and be beneficially recycled. 
   Product recovery, as considered in this invention, has distinct operational phases: a) in a first phase, 98% to more than 99% of the product is recovered while the pipeline system is under pressure (propane, for instance will be under roughly 200 to 250 psig of pressure) either from the pipeline due to product volatility or from nitrogen (from the storage area of the invention) applied to “chase” the pipeline product out of the pig trap; b) in a second phase, residual product that cannot be recovered is “sucked” out using vacuum and is combusted; c) a purge phase where the pipeline equipment is purged to the point that the system is safe to open, and finally d) recycling of the product that occurs when the recovery stage is complete. The recycle phase can be performed either onsite based on the instructions from the operations person or be performed offsite at an arranged location. 
   Once the equipment in the invention is set up, connected, and operating as defined in the prior section, the equipment operator can initiate the product recovery mode and follow the steps as outlined as follows: 
   1) Open the pig trap drain valve  105  and allow the flexible connecting tubing (not shown) to fill with the pipeline product previously isolated in the pig trap  107 . Then open the system block valve  200 . At this point there should be a reading of the pressure in the pig trap  107  on a pressure indicator  205 . Once the pressure on the pressure indicator  205  has been noted, slowly open the product recovery block valve  210 . At this point there should be a sound of product liquid entering the product recovery tank  240 . The operator should watch a level indicator  250  on the product recovery tank  240  and the pressure indicator  250  while product is being recovered.
 
2) Once the sound of the flow of recovered product diminishes, the flow meter  227  can be monitored. Once flow stops due to the pressure equalization between the pig trap  107  and the product recovery tank  240 , the nitrogen purge valve  380 , which was originally connected to the pig trap blow down valve  104 , can be opened to blow nitrogen through the pig trap  107 . This will chase out any remaining liquid in the trap  107  to the product recovery tank  240 . The equipment operator should now check the flow that has occurred through the flow meter  227  and compare the flow meter  227  reading to a calculation of the volume of fluid isolated in the trap  107 . If the flow meter  227  reading and the pig trap  107  volume calculation are reasonably close, say within 5%, the product can be considered recovered and the purge mode can begin. Otherwise, the pig trap  107  should be chased with nitrogen until more product is recovered.
 
   At this point the pig trap is considered to be empty of free flowing product and the purge cycle can begin. 
   The Product Purge Mode 
   The purpose of the purge mode of operation of the invention is to scavenge and purge the remaining hydrocarbon products, generally less than 2% of the original isolated volume, from the pig trap  107  without releasing or venting to the atmosphere or utilizing a flare. Meeting these two conditions of no venting and no flaring meets and exceeds the most stringent environmental regulations. Venting has stringent monitoring and reporting requirements that require expensive equipment and extensive reporting. Flaring is subject to complex regulations under the Code of Federal Regulations, 40 CFR §60.18, that requires the equipment operator to install expensive monitoring equipment, requires periodic testing, and requires extensive reporting. Since no flare is used in the purging process, the operator does not have to incur the capital costs, high maintenance costs, recordkeeping requirements, and manpower required to comply with 40 CFR §60.18. 
   In addition, much of the cost of the product recovery and purging process is offset by the beneficial use of the product that was vented or flared in operations prior to the invention. 
   The previously described recovery process extracts and saves to the product recovery tank  240  about 98% of the hydrocarbon product isolated in the trap  107 . A 6 inch pipeline pig trap, which will have an 8 inch diameter trap barrel some 6 feet in length with and 2 feet of 6 inch pipe will contain roughly 20 gallons of isolated product. The objective of the purging operation is therefore to remove less than 0.5 gallon of product remaining in the equipment without letting any product go to the atmosphere. Much of the product will be in the bottom of the trap  107  and will freely drain through the drain valve  105 . 
   Once the product recovery mode is complete, the following operations should be performed for system purging and scavenging for remaining hydrocarbon vapors and residual liquids: 
   a) The product recovery block valve  210  should be closed and the lock should be removed from the purge system block valve  430  and placed on the product recovery block valve  210 . The product recovery tank block valve  230  should be left open to prevent any pocketing of hydrocarbon vapors, in the event a highly volatile product has been recovered. The nitrogen valve  380  can be shut or throttled to low flow—shut being the generally preferred condition at the outset of the purge operations;
 
b) The invention operating personnel should make sure that the nitrogen test meter is running and connected to a sample point  550 , that the engine emissions analyzer  670  is running and connected to a sample point  570  and may be easily connected to a sample point  590 . In addition, the computer  660  should be running and able to acquire data from the engine analyzer  670  measuring the unburned hydrocarbon emissions from the sample points  570  and  590 ;
 
c) The engine  560 , which functions as an oxidizer for the invention, should be running and the emissions analyzer  670  and the computer  660  should be calculating lambda (λ) for the operating engine;
 
d) A liquid accumulator drain valve  450  should be open and a nitrogen valve  470  should be closed a drain valve  490  to a liquid accumulator  480  should be closed;
 
e) Begin purging material to the vacuum pump  540  by slowly opening the purge system block valve  430 . Stop opening when the ball valve handle is between an angle of 30 degrees to 45 degrees. Wait about a minute and listen if the vacuum pump  540  begins to load and feel the line with the hand between the purge system block valve  430  and the liquid knock out drum  440 . This segment of line should become noticeably cooler over the next 60 to 120 seconds.
 
f) If the line segment described above becomes cooler, the liquid should be scavenged from the isolated portion of the pipeline equipment  107  in roughly 10 to 15 minutes.
 
g) At the end of the purging and scavenging portion of the operation, the person in charge of operating the pipeline  100  equipment may desire to further purge the pipeline equipment with additional nitrogen  350 . If this is desired, open the nitrogen purge block valve  380  and allow enough nitrogen to flow to turn over two to three times the volume of the isolated product. This purging with nitrogen will normally be enough so that the pig trap  107  may be opened to remove a pig trapped in the pig trap.
 
h) At the end of the purging process, shut down the engine  560 , the vacuum pump  540 , shut the nitrogen valves  340  and  380 , open the liquid accumulator drain valve  490  and allow any accumulated liquid to flow into the product recovery tank  240 . Once the liquid in the accumulator is sent to the product recovery tank  240 , then the accumulator drain valve  490  should be closed again. The purge system block valve  430  should be closed and locked. The system block valve  200  should be closed and the flexible line removed from the system block valve  200  and the trap drain valve  105 . The nitrogen line should be removed from the nitrogen purge block valve  380  and the trap blow down valve  104 .
 
Operating in the Product Return or Recycle Mode
 
   Based on the product purity and contamination specifications, the recovered product in the product recovery tank  240  may now be returned to the pipeline system  100  or beneficially recycled to an offsite facility. 
   The procedure to return the product to the pipeline system can be performed as follows:
     a) Connect a temporary line (not shown) to a pipeline blow down valve  109  to the product return block valve  420 .   b) Close the product recovery block valve  230 , open the flow reversal valve  223 , make sure the product recovery block valve is closed  210 , and open the pump block valve  400  and the product return block valve  420 .   c) Reset the flow meter  227  to zero or note the totalized flow reading.   d) Start a product return pump  410  and allow the pump to return the product back to the pipeline system  100 .   e) Once the product recovery tank  240  is empty, remove the temporary line from the pipeline blow down valve  109  and from the product return block valve  420 .   f) Return the equipment settings and positions to the settings in the product recovery operational mode disclosed elsewhere herein.   

   At this point the product recovery, purging and product return operations at this site are complete. 
   
     
       
             
           
             
             
             
           
         
             
               TABLE 2 
             
           
           
             
                 
             
             
               Parts List 
             
           
        
         
             
               # 
               Name 
               Purpose 
             
             
                 
             
             
               FIG. 1 
               Pipeline Equipment 101-109 
               Invention Example - This is a common activity in 
             
             
                 
                 
               pipeline operations, however, other examples 
             
             
                 
                 
               could be used, such as changing the filter in a 
             
             
                 
                 
               meter run, changing prover balls, etc. 
             
             
               100 
               Pipe line system 
               The system through which pipe line products flow 
             
             
                 
                 
               from one destination to another. 
             
             
               101 
               Trap Valve Block valve) 
               Allows pig or swab to enter and isolates the pig or 
             
             
                 
                 
               swab from the pipeline system. The valve is 
             
             
                 
                 
               normally closed but is open during pigging 
             
             
                 
                 
               operations. 
             
             
               102 
               Trap Bypass Valve (block 
               The path of flow during normal non-pigging 
             
             
                 
               valve) 
               operations. During pigging operations, this valve is 
             
             
                 
                 
               closed until the pig is in the pig trap. Then the 
             
             
                 
                 
               valve is reopened in the process described herein. 
             
             
               103 
               Jump Over Valve (block 
               The Jump Over Valve enables flow through the 
             
             
                 
               valve) 
               pig trap when the trap valve 101 is open. Closing 
             
             
                 
                 
               the trap valve 101 and the jump over valve isolates 
             
             
                 
                 
               the pig trap so the pig can be removed. 
             
             
               104 
               Blow Down Valve 
               A small valve used to provide access to the pig 
             
             
                 
                 
               trap for purging the pig trap before opening. The 
             
             
                 
                 
               invention uses this as one of two connections for 
             
             
                 
                 
               the recovery of the product material with the pig in 
             
             
                 
                 
               the pig trap. 
             
             
               105 
               Trap Drain Valve 
               The Trap Drain Valve is opened to drain the 
             
             
                 
                 
               trapped product out of the pig trap so the pig can 
             
             
                 
                 
               be recovered. This drain valve is a connection for 
             
             
                 
                 
               the invention to recover trapped product. 
             
             
               106 
               Trap Closure 
               The trap closure is the method of inserting and 
             
             
                 
                 
               removing the pig or swab from the pig trap. The 
             
             
                 
                 
               trap closure is normally a “hammer flange” with a 
             
             
                 
                 
               gasket and is opened by hitting he flange with 
             
             
                 
                 
               spark proof sledge hammer so that it screws on or 
             
             
                 
                 
               off. 
             
             
               107 
               Trap Barrel 
               The trap barrel is normally 2 inches larger in 
             
             
                 
                 
               diameter than the incoming pipeline diameter. This 
             
             
                 
                 
               allows enough room to insert and remove the pig 
             
             
                 
                 
               or swab from the 
             
             
               108 
               Test Valve 
               This valve is used for the testing of pipeline 
             
             
                 
                 
               product composition when the pipeline is being 
             
             
                 
                 
               emptied with another product like nitrogen to test 
             
             
                 
                 
               when to begin recovering product to the invention 
             
             
                 
                 
               rather than sending the product on down the line. 
             
             
               109 
               Pipeline Blow Down Valve 
               This is a small valve like 104 described above 
             
             
                 
                 
               except that it is located on the pipeline/pressurized 
             
             
                 
                 
               side of the pig trap and is used as a return point for 
             
             
                 
                 
               product recovered by the invention. 
             
             
               FIG. 2 
               Diagram of the Invention 
             
             
               200 
               System Block Valve 
               This valve controls all recovery operations. This 
             
             
                 
                 
               valve is connected by flexible pressure capable 
             
             
                 
                 
               piping to the trap drain valve 105 using the 
             
             
                 
                 
               smallest practical tubing diameter. 
             
             
               205 
               Pressure Indicator 
               This pressure indicator shows the pressure in the 
             
             
                 
                 
               pig trap 107 once one has entered the product 
             
             
                 
                 
               recovery mode 
             
             
               210 
               Product Recovery Block 
               This valve provides access to the Product 
             
             
                 
               Valve 
               Recovery Tank 240 
             
             
               220 
               Product Recovery Check 
               This component prevents flow reversal of 
             
             
                 
               Valve 
               recovered product into the vacuum purge system 
             
             
               223 
               Flow Reversal Valve 
               This valve is opened along with valve 400 and 
             
             
                 
                 
               valve 230 and valve 210 is closed so flow can be 
             
             
                 
                 
               metered through the pump 410 
             
             
               227 
               Flow Meter 
               This flow meter measures the flow rate and total 
             
             
                 
                 
               flow to the product recovery tank 240 and the 
             
             
                 
                 
               amount of product off loaded through the product 
             
             
                 
                 
               pump 410 
             
             
               230 
               Product Recovery Tank 
               This valve is normally open but is provided to 
             
             
                 
               Block Valve 
               allow maintenance and change out of other 
             
             
                 
                 
               equipment in the recovery system. 
             
             
               240 
               Product Recovery Tank 
               This is a holding tank for recovered product from 
             
             
                 
                 
               the pipeline pig trap or other operation. The 
             
             
                 
                 
               product is held and either re-injected into the 
             
             
                 
                 
               pipeline at the pipeline blow down valve 109 or 
             
             
                 
                 
               carried to a recycling facility at another location. 
             
             
               250 
               Level Indicator Sight Glass 
               The level indicator is any one of several types of 
             
             
                 
                 
               level indicators that may be used to monitor the 
             
             
                 
                 
               level in the product recovery tank - for this 
             
             
                 
                 
               particular example a sight glass and level bridle is 
             
             
                 
                 
               shown. 
             
             
               260 
               Pressure Indicator 
               The pressure indicator is a pressure gauge to show 
             
             
                 
                 
               the pressure in the product recovery tank 240. 
             
             
               270 
               Relief Block Valve 
               This is a block valve that is normally open and 
             
             
                 
                 
               would be car sealed open that can be closed to 
             
             
                 
                 
               perform maintenance on the pressure relief valve 
             
             
                 
                 
               290 or rupture disk 280. 
             
             
               280 
               Rupture Disk 
               The rupture disk is a portion of the safety system 
             
             
                 
                 
               and is designed to rupture some 10 psia lower than 
             
             
                 
                 
               the relief valve 290. The rupture disk is provided 
             
             
                 
                 
               to prevent potential corrosion in the relief valve 
             
             
                 
                 
               290. 
             
             
               290 
               Relief Valve 
               The relief valve is provided for any overpressure 
             
             
                 
                 
               event that might occur when product is sent to the 
             
             
                 
                 
               product recovery tank 240, e.g., there is volatile 
             
             
                 
                 
               high pressure product contained in the pig trap and 
             
             
                 
                 
               that product is accidentally sent to the product 
             
             
                 
                 
               recovery tank 240 
             
             
               300 
               Nitrogen Blanket Check 
               This is a check valve provided so that flow 
             
             
                 
               Valve 
               reversal into the nitrogen system from the product 
             
             
                 
                 
               recovery tank 240 will not occur. 
             
             
               310 
               Regulator Block Valve 
               This is one of two regulator block valves so that 
             
             
                 
                 
               the nitrogen pressure regulator 320 can be 
             
             
                 
                 
               maintained. 
             
             
               320 
               Nitrogen Pressure 
               The nitrogen pressure regulator controls the 
             
             
                 
               Regulator 
               pressure of the nitrogen blanket on the recovered 
             
             
                 
                 
               product in the product recovery tank 240. The 
             
             
                 
                 
               ability to control the pressure in the product 
             
             
                 
                 
               recovery tank 240 allows flow and net positive 
             
             
                 
                 
               suction head to be controlled by the equipment 
             
             
                 
                 
               operator. 
             
             
               330 
               Regulator Block Valve 
               This is one of two block valves so that the nitrogen 
             
             
                 
                 
               pressure regulator 320 can be maintained. 
             
             
               340 
               Nitrogen Block Valve 
               This is the valve controlling access to a source of 
             
             
                 
                 
               nitrogen used for blanketing and purging during 
             
             
                 
                 
               product recovery operations of the invention. The 
             
             
                 
                 
               nitrogen source could be bottled nitrogen, liquefied 
             
             
                 
                 
               nitrogen or manufactured nitrogen. 
             
             
               350 
               Nitrogen Source 
               This is the nitrogen source for the purging and 
             
             
                 
                 
               blanketing operations of the invention and may be 
             
             
                 
                 
               bottled nitrogen, liquefied nitrogen, or 
             
             
                 
                 
               manufactured nitrogen from a permeable 
             
             
                 
                 
               membrane system 
             
             
               360 
               Vaporization Exchanger 
               The product recovery tank 240 may include an 
             
             
                 
                 
               internal vaporization exchanger inside the product 
             
             
                 
                 
               recovery tank 240 to vaporize liquid nitrogen and 
             
             
                 
                 
               thereby cool higher vapor pressure products in the 
             
             
                 
                 
               product recovery tank 240, e.g., ethylene 
             
             
               370 
               Vaporization Exchanger 
               This valve controls the flow of cooling material 
             
             
                 
               Block Valve 
               liquid nitrogen to the vaporization exchanger 360. 
             
             
               380 
               Nitrogen Purge Block 
               This valve controls the flow of nitrogen 350 used 
             
             
                 
               Valve 
               as a purge gas during and after the recovery 
             
             
                 
                 
               operations have occurred. 
             
             
               390 
               Recycle Valve 
               This valve is for the off loading of recovered 
             
             
                 
                 
               product at a product recycle location which is not 
             
             
                 
                 
               necessarily at the location where the recovery 
             
             
                 
                 
               occurred. Recovered product may be off loaded by 
             
             
                 
                 
               opening this valve and pressuring up the recovery 
             
             
                 
                 
               tank 240 with nitrogen 350 
             
             
               400 
               Pump Block Valve 
               This valve blocks in the recycle pump 410. The 
             
             
                 
                 
               recycle pump is capable of returning product held 
             
             
                 
                 
               in the product recovery tank 240 back to the 
             
             
                 
                 
               pipeline through the pipeline blow down valve 
             
             
                 
                 
               109. 
             
             
               410 
               Product Return/Recycle 
               This product return or recycle pump returns the 
             
             
                 
               Pump 
               recovered material in the product recovery tank 
             
             
                 
                 
               240 back to the pipeline system 100. The pump is 
             
             
                 
                 
               capable of pump pressures that enable the 
             
             
                 
                 
               recovered product to be returned to the pipeline 
             
             
                 
                 
               system 100 which may be several hundred pounds 
             
             
                 
                 
               per square inch. 
             
             
               420 
               Product Return Block 
               This valve controls the off loading of recycled 
             
             
                 
               Valve 
               product back to the pipeline system 100. This 
             
             
                 
                 
               valve is connected using flexible piping to the 
             
             
                 
                 
               pipeline blow down valve 109. 
             
             
               430 
               Purge System Block Valve 
               Opening this valve activates the vacuum purge 
             
             
                 
                 
               system. 
             
             
               440 
               Liquid Knock Out Drum 
               The liquid knock out drum recovers entrained 
             
             
                 
                 
               liquid in the vapor stream to the vacuum pump. 
             
             
                 
                 
               Liquid may be either entrained in the vapor or 
             
             
                 
                 
               prevents damage to the vacuum pump if the Purge 
             
             
                 
                 
               system Block Valve 430 is accidentally opened. 
             
             
                 
                 
               The product recovery check valve 220 prevents 
             
             
                 
                 
               recovered product from being drawn from the 
             
             
                 
                 
               product recovery tank 240 into the vacuum purge 
             
             
                 
                 
               system. 
             
             
               450 
               Liquid Drain 
               This valve allows liquids accumulated in the 
             
             
                 
                 
               Liquid Knock Out Drum 440 to free drain into the 
             
             
                 
                 
               Liquid Accumulator 480 so that there is little or no 
             
             
                 
                 
               liquid level in the liquid knock out drum 440. 
             
             
               460 
               Pressure indicator on liquid 
               This is a pressure indicator used when the liquid 
             
             
                 
               accumulator 
               drain valve 450 is closed and the liquid 
             
             
                 
                 
               accumulator is pressured with nitrogen by opening 
             
             
                 
                 
               the liquid accumulator nitrogen valve 470. When 
             
             
                 
                 
               the liquid accumulator pressure indicator is greater 
             
             
                 
                 
               than the pressure read on the pressure indicator 
             
             
                 
                 
               260 on the product recovery tank 240, then the 
             
             
                 
                 
               accumulator drain valve 490 is opened and liquid 
             
             
                 
                 
               in the liquid accumulator 480 is sent to the product 
             
             
                 
                 
               recovery tank 240. 
             
             
               470 
               Nitrogen Pressurization 
               When the Liquid drain valve 450 is closed then 
             
             
                 
               Valve 
               the nitrogen pressurization valve is opened until 
             
             
                 
                 
               the pressure on the pressure indicator 460 is 
             
             
                 
                 
               greater than the pressure on the pressure indicator 
             
             
                 
                 
               260 located on the product recovery tank 240. The 
             
             
                 
                 
               liquid accumulator drain valve 490 is then opened 
             
             
                 
                 
               and any accumulated liquid is sent to the product 
             
             
                 
                 
               recovery tank 240. Once the liquid has been sent to 
             
             
                 
                 
               the product recovery tank 240 from the liquid 
             
             
                 
                 
               accumulator 480, then the nitrogen valve is closed 
             
             
                 
                 
               470, the liquid accumulator drain valve 490 is 
             
             
                 
                 
               closed and the liquid drain valve 450 is reopened 
             
             
                 
                 
               for any additional liquid to pass to the liquid 
             
             
                 
                 
               accumulator 480. 
             
             
               480 
               Liquid accumulator 
               The liquid accumulator retains any liquids 
             
             
                 
                 
               gathered by the liquid knockout drum 440 until 
             
             
                 
                 
               sufficient liquid is present to be sent to the product 
             
             
                 
                 
               recovery tank 240. 
             
             
               490 
               Liquid accumulator drain 
               The liquid accumulator drain valve, when opened 
             
             
                 
               valve 
               and the liquid accumulator 480 is pressurized, 
             
             
                 
                 
               allows accumulated liquid entrained in the purging 
             
             
                 
                 
               operation to be sent to the product recovery tank 
             
             
                 
                 
               240 
             
             
               500 
               Liquid accumulator check 
               The liquid accumulator check valve prevents flow 
             
             
                 
               valve 
               reversals due to pressure differences between the 
             
             
                 
                 
               vacuum in the liquid knock out drum 440 and the 
             
             
                 
                 
               pressure in the product recovery tank 240 
             
             
               510 
               Regulator Block Valve 
               This valve is present to allow maintenance and/or 
             
             
                 
                 
               replacement of the pressure regulator on the 
             
             
                 
                 
               product recovery tank 240. 
             
             
               520 
               Product Recovery Tank 
               This regulator maintains a constant pressure on the 
             
             
                 
               240 Pressure Regulator 
               product recovery tank that can fluctuate during 
             
             
                 
                 
               filling operations and/or when flash vaporization 
             
             
                 
                 
               occurs in the product recovery tank 240. Pressure 
             
             
                 
                 
               regulation in emptying operations is controlled by 
             
             
                 
                 
               the nitrogen pressure regulator 320. 
             
             
               530 
               Regulator Block Valve 
               This valve is present to allow maintenance and/or 
             
             
                 
                 
               replacement of the pressure regulator on the 
             
             
                 
                 
               product recovery tank 240. 
             
             
               540 
               Vacuum Pump 
               Once the initial product recovery is complete and 
             
             
                 
                 
               the maximum amount of product is stored in the 
             
             
                 
                 
               product recovery tank 240, the purging process is 
             
             
                 
                 
               initiated by using a vacuum pump. This is 
             
             
                 
                 
               accomplished by closing valve 210 and opening 
             
             
                 
                 
               valve 430 which begins to draw unrecovered 
             
             
                 
                 
               product from the pig trap through the drain valve 
             
             
                 
                 
               105 and temporary piping connecting the system 
             
             
                 
                 
               block valve 200. Drawing a vacuum on the 
             
             
                 
                 
               remaining product in the pig trap will tend to 
             
             
                 
                 
               vaporize any remaining product as can be seen 
             
             
                 
                 
               when the thermodynamic and physical properties 
             
             
                 
                 
               of the recovered products are examined. 
             
             
               550 
               Sample Point 2 
               This sample point is located on the discharge of 
             
             
                 
                 
               the vacuum pump, which has a pressure higher 
             
             
                 
                 
               than atmospheric pressure and enables sampling of 
             
             
                 
                 
               the percentage of product and the percentage of 
             
             
                 
                 
               nitrogen, used as a purge gas through valve 380. 
             
             
                 
                 
               This allows the operator to determine when the 
             
             
                 
                 
               purge operation has reduced the product 
             
             
                 
                 
               concentration to the point that the product recovery 
             
             
                 
                 
               and purge is complete. 
             
             
               560 
               Engine 
               This is an internal combustion engine capable of 
             
             
                 
                 
               running on low octane fuels. The engine drives an 
             
             
                 
                 
               air compressor 565 designed to load the engine to 
             
             
                 
                 
               increase the engine&#39;s fuel consumption. An engine 
             
             
                 
                 
               normally has an unburned hydrocarbon 
             
             
                 
                 
               concentration between 10 and 100 parts per 
             
             
                 
                 
               million by volume and is vastly more efficient than 
             
             
                 
                 
               flaring - whose efficiency is generally 98 to 99 
             
             
                 
                 
               percent combustion or roughly 10,000 to 20,000 
             
             
                 
                 
               parts per million by volume concentration of 
             
             
                 
                 
               unburned hydrocarbons. 
             
             
                 
                 
               The discharge from the vacuum pump 540 is sent 
             
             
                 
                 
               directly to the inlet air suction of the engine and 
             
             
                 
                 
               the hydrocarbon is combusted/oxidized in the 
             
             
                 
                 
               engine. Engine performance is monitored by an 
             
             
                 
                 
               engine analyzer at sample point 3 570. 
             
             
               565 
               Air Compressor 
               The purpose of the air compressor is to provide a 
             
             
                 
                 
               variable load for the engine 560 and to make the 
             
             
                 
                 
               engine 560 require more fuel and increase the 
             
             
                 
                 
               amount of gases that can be combusted from the 
             
             
                 
                 
               vacuum pump 540. 
             
             
               570 
               Sample Point 3 
               Sample point 3 is the location where the 
             
             
                 
                 
               performance of the engine may be ascertained. By 
             
             
                 
                 
               measuring the residual oxygen concentration in the 
             
             
                 
                 
               combustion gas, the carbon dioxide concentration, 
             
             
                 
                 
               and the outlet nitrogen, the value of lambda λ) can 
             
             
                 
                 
               be determined. The value of lambda allows a 
             
             
                 
                 
               butterfly valve to be adjusted on the air intake to 
             
             
                 
                 
               compensate engine performance while combusting 
             
             
                 
                 
               the outlet gas from the discharge of the vacuum 
             
             
                 
                 
               pump 540 
             
             
               580 
               Catalytic Converter 
               The purpose of the catalytic converter is to further 
             
             
                 
                 
               combust/oxidize unburned hydrocarbon that might 
             
             
                 
                 
               remain in the engine exhaust stream from the 
             
             
                 
                 
               engine 560 
             
             
               590 
               Sample Point 4 
               The purpose of sample point 4 is the location 
             
             
                 
                 
               where the overall air emissions of the product 
             
             
                 
                 
               recovery and product purging process are located. 
             
             
                 
                 
               An engine analyzer may be used for this to provide 
             
             
                 
                 
               he concentration of unburned hydrocarbons 
             
             
               600 
               Emergency flare check 
               This component prevents flow reversal in the 
             
             
                 
               valve 
               emergency flare system that automatically actuates 
             
             
                 
                 
               if the vacuum pump cannot retain a vacuum on the 
             
             
                 
                 
               purging system. 
             
             
               610 
               Regulator Block Valve 
               This component enables the regulator 620 to be 
             
             
                 
                 
               maintained 
             
             
               620 
               Emergency Regulator 
               This regulator allows flow to an “emergency flare” 
             
             
                 
                 
               or vent in the event an excess of gas or vapor is 
             
             
                 
                 
               encountered that cannot be handled by the vacuum 
             
             
                 
                 
               pump 540. The regulator is used to be able to 
             
             
                 
                 
               predetermine the point at which emergency action 
             
             
                 
                 
               takes place. 
             
             
               630 
               Regulator Block Valve 
               This component enables the regulator 620 to be 
             
             
                 
                 
               maintained 
             
             
               640 
               Emergency Flare or Vent 
               This is for system safety in the event “slugs” of 
             
             
                 
                 
               vapor or entrained gas are encountered. 
             
             
               650 
               Nitrogen analyzer 
               This meter is used at sample point 1 108 and 
             
             
                 
                 
               sample point 2 550 to determine the nitrogen 
             
             
                 
                 
               concentration. The information from the nitrogen 
             
             
                 
                 
               meter at sample point 1 108 is used to determine 
             
             
                 
                 
               when the product recovery phase is initiated if a 
             
             
                 
                 
               line is being pigged with nitrogen. The nitrogen 
             
             
                 
                 
               concentration at sample point 2 550 provides 
             
             
                 
                 
               information as to the progress of the purging 
             
             
                 
                 
               operation following the product recovery phase of 
             
             
                 
                 
               operation 
             
             
               660 
               Computer 
               The computer is used to monitor, compute 
             
             
                 
                 
               algorithms and gather data related to the engine 
             
             
                 
                 
               analyzer 670 and its two monitoring locations 
             
             
               670 
               Engine analyzer 
               The engine analyzer is used to analyze the 
             
             
                 
                 
               following combustion products after the 
             
             
                 
                 
               combustion at sample point 3 570 and the catalytic 
             
             
                 
                 
               oxidation at sample point 4 590. The analyzer 
             
             
                 
                 
               should be capable of reading unburned 
             
             
                 
                 
               hydrocarbons, carbon dioxide, and unconsumed 
             
             
                 
                 
               oxygen at a sample rate occurring less than once a 
             
             
                 
                 
               minute. Sample point 3 570 monitors engine 
             
             
                 
                 
               performance and sample point 4 590 monitors 
             
             
                 
                 
               environmental emissions performance. 
             
             
                 
             
           
        
       
     
   
   While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.

Technology Classification (CPC): 8