Liquid product distribution system

Abstract: A liquid distribution system suitable in use for the substantially contamination free collection of one of a variety of liquid products of differing character from a selected source, and/or the substantially contamination free delivery of a said product to a selected one of a variety of destinations. The preferred embodiment utilises a novel manifold and manifold system and a novel rotary valve unit. The preferred manifold incorporates a pig which travels the length of a common conduit of the manifold between deliveries of different liquids. Satellite conduits are connected at T junctions between the extremities of the common conduit via the novel rotary valve unit. An off-take connection including a main valve is connected at a T junction spaced from the satellite junctions and the nearest extremity of the common conduit. The rotary valve unit is designed to conform to the inner surface of the common conduit in its closed position to provide a smooth unobstructed path for the pig, which is operated by pressure of the product to be delivered.

Description: Field of the Invention The present invention relates to a liquid distribution system suitable for the substantially contamination free collection of one of a variety of liquid products of differing character from a selected source, and/or the substantially contamination free delivery of such a product to a selected one of a variety of destinations. By "liquid product" is meant a material in a pumpable form which may vary from a mobile liquid such as alcohol or a light hydrocarbon which may be a compressed liquid (i.e. gaseous at ambient pressure) to a viscous or paste-like material such as a sludge. The invention is especially concerned with products employed in the chemical and petroleum industries. Background of the Invention In industry and trade there are many applications where, during production and filling, a large number of base or finished products, or components and additives, from numerous sources must be distributed to a certain destination or "place of action". Such places, sometimes called "consumers", may be e.g. blending tanks, scales, meters, loading and filling facilities or reactors. Thus, for example, a particular product may need to be selected from a bank of storage tanks located at one end of a facility and delivered to a selected reactor or blending tank at a remote part of the facility. If each product were to be delivered to an individual destination by a separate pipeline, this would hardly be possible for lack of space and would be prohibitively expensive. In the past distribution systems were developed and installed utilising e.g. hoses with coupling devices. Such systems are still in operation and constitute the state of the art. Products are pumped from storage tanks via pipelines to a central distribution point called a "snake pit" from whence other pipe lines lead to various destinations. The snake pit can contain a hundred or more hoses whose handling always represents an operational safety risk. Handling of the hoses calls for great physical exertion and can lead to accidents and mistakes which can have serious consequences. Likewise, assuring proper hose connection is not without problems. Since a single pipe to a consumer may have to carry different products, pipelines to consumers are now normally cleaned by pigs, or interior mobile cleaning devices. "Pig" herein can have the engineering meaning given in the McGraw-Hill Dictionary of Scientific and Technical Terms (1974 Edition). To solve the problem of proper and safe product distribution special systems have been marketed, most calling for great mechanical effort in manufacturing, making them expensive for acquisition and operation. In a prior system (DE-A-4 119 743), a common conduit is provided to which a plurality of supply conduits are connected, each comprising a valve, and in which, in addition, a plurality of satellite conduits connect the common conduit to different destinations with a satellite valve in each satellite conduit. Further, the common conduit comprises a pig trap for a sole pig. The pig can be moved through the common conduit by means of pressurized air to effect cleaning of the common conduit. To return the pig to the pig trap located at the end of the common conduit upstream of the first supply conduit, a return conduit is connected between the end of the common conduit upstream of the pig trap and its end downstream of the last satellite conduit. In the cleaning cycle, the pig, therefore, circulates from the pig trap through the common conduit and through the return conduit back into the pig trap. This system, therefore, requires a return conduit just for circulating the pig which return conduit might be very long since the ends of the common conduit may be located at relatively far remote positions. Another prior system (EP-A-0 375 533) comprises a common conduit to which a supply conduit and a plurality of satellite conduits are connected through valves wherein the satellite conduits connect the common conduit selectively to one of a plurality of destinations. In the common conduit, two pigs are provided. In feeding operation one of the pigs is positioned at a first end of the common conduit adjacent to the supply conduit and the other pig is held in a position just downstream of the satellite conduit opened to thereby close the remaining downstream section of the common conduit against entrance of liquid supplied by the supply conduit. For cleaning purposes, the first pig is moved through the common conduit from the pig trap at the upstream end of the common conduit to the open satellite conduit until it contacts the second pig. Thereafter, both pigs are moved back along the common conduit to its upstream end. It is the object of the present invention to provide for a simple, low cost production distribution system permitting simple cleaning after conveying a liquid product through a common conduit. Summary of the Invention The invention provides for a manifold system connectable in use for the collection of one of a variety of liquid products of differing character from a selected source, or the delivery of a said product to a selected one of a variety of destinations which comprises a manifold having a common conduit connecting a plurality of satellite conduits themselves connectable with respective said sources or destinations, a satellite valve in each satellite conduit, a connecting conduit leading from said common conduit at a position spaced from the satellite conduits, a main valve in said connecting conduit, cleaning means comprising a sole pig operable for freeing said common conduit of contaminants between conveyance of different said products, wherein said common conduit extends from a first point beyond a first satellite conduit furthermost from said connecting conduit to a second point beyond a junction with said connecting conduit, and at least one pig trap for parking said pig, and which system is characterized by a first pig trap at said first point and a second pig trap at said second point, wherein said pig is arranged to be actuated in one direction by hydraulic pressure of a said product and in the other direction by pneumatic means and wherein both hydraulic pressure and pneumatic pressure are to be applied to the dead end of the respective pig trap. This system permits cleaning of the common conduit by simple reciprocation of a sole pig in a simple and effective manner. The manifold system of the invention may be designed to be suitable for the collection of a liquid product selected from a plurality of sources. This includes a pilot manifold comprising a central pilot line connecting the first pig trap to a plurality of pilot lines each containing a pilot valve, the pilot lines being respectively associated with a respective satellite conduit and connected thereto at a connection point on the far side of the respective satellite valve from the central conduit. The manifold system of the invention may also be designed to be suitable for the delivery of a liquid product to a selected one of a variety of destinations. Such a system may e.g. include a pilot line connecting the second pig trap to a connection point on the far side of the main valve from the central conduit, the first pig trap being connected to a pneumatic gas source via a gas valve, and to an exhaust line via an exhaust valve. Brief Description of the Drawings Embodiments of the invention are hereafter described with reference to the accompanying drawings, in which: Figure 1 is a circuit diagram of a first form of manifold system, Figure 2 is a diagrammatic vertical cross-sectional view of the manifold system of Figure 1 showing a single satellite conduit and associated pilot line. Description of Preferred Embodiments Figure 1 illustrates schematically a manifold system comprising a manifold 10 having a main or common conduit 11 and e.g. twenty satellite conduits 12, only the four endmost of which, at each end, are shown in detail. As shown by these end conduits 12 each of the conduits 12 contains a satellite valve 13. The manifold system of this embodiment is suitable in use for the collection of one of a variety of liquid products and when arranged in situ each satellite conduit 12 will be connected from the remote end of its valve 13 through a pump to a respective source such as a storage tank. A connecting conduit 14 leads from the common conduit 11 at a position spaced (in this embodiment downstream) from the satellite conduits 12, and contains a main valve 15 which may be fitted with a flow meter 16. As will become apparent the satellite conduits 12 and connecting conduit 14 are connected via their valves 13 and 15 at T junctions and the common conduit is a smoothly extending pipe which may be straight as shown in Figure 1 or have a gradual curve as in Figure 2. An important feature of the invention lies in the provision of cleaning means in association with the manifold for freeing the common conduit 11 of contaminants. In the manifold system this is operable between the conveyance of different products to free the conduit from contaminants which may arise from the previous product. Preferably as shown in Figures 1 and 2 the cleaning means takes the form of a pig 17 located within the common conduit 11 and movable past the satellite connections and connecting conduit between pig traps 18, 19 at respective extremities of the conduit. The pig trap 18 defines a rest position in the present embodiment and the trap 19 an active position. As shown in Figure 1 each satellite conduit 12 is connected at the far side of its valve 13 to the remote or dead end of the pig trap 18 by a pilot line 20 containing a pilot valve 21. In this Figure the pilot lines are connected with the dead end of trap 18 through a central pilot line 20a of a manifold which is only shown diagrammatically. In practice the lines from the trap to the pilot valves, in particular the length of any common pilot line, 21 can be kept short to reduce any contamination through product remaining there between operations. In the operation of this embodiment the pig is driven from its rest position in pig trap 18 to the active position in pig trap 19 by the hydraulic pressure of product flowing in a selected pilot line. In doing so it frees the common conduit of air and ensures that no contaminant remains from earlier operations. The pig trap 19, which is downstream in the present embodiment, is connected at its dead end through return valve 22 to a source of compressed air or other pneumatic gas for return to the rest position at pig trap 18 after an operation. It is also connected through exhaust valve 23 to waste, so that air in the conduit 11 and any contaminants picked up by the pig can be discharged during active movement of the pig. Figure 2 shows the construction of the manifold in more detail than Figure 1, but only one of the satellite conduits 12 and associated components is shown for the sake of clarity and to illustrate the operation of the manifold system. It can be seen that the satellite valve has a rotatable ball member which in the closed position conforms to the cylindrical surface of the common conduit, thereby creating no dead volume or projection to impede the cleansing action of the pig 17 which can sweep the whole inner surface clean. Although the pig may be put into operation manually it is preferred to use automatic means to control the sequence of steps. The position of the pig at various points on its course is detected by sensors. Sensors 37 and 38 (Figure 2) are positioned to detect the presence of the pig respectively in the traps 18 and 19. Sensor 39 is positioned downstream of the final or last downstream satellite connection and sensor 40 upstream of the junction with the connection conduit 14. The automatic circuit arrangement will be evident from the sequence of operations. The manifold system of Figures 1 and 2, e.g. when connected in a liquid distribution system arranged for collection of a selected liquid product, operates as follows. i Upon selection of a said product or source the corresponding pilot valve 21 is first opened, and also the exhaust valve 23 in the active pig trap 19, causing the selected product to flow to the pig trap 18 under sufficient pressure to push the pig 17 from its rest position in trap 18 to its active position in pig trap 19. The passage of the pig 17 frees the conduit 11 of any contaminant which is driven out with the contained air through the exhaust valve 23. ii Passage of the pig 17 past sensor 39, i.e. after the last satellite connection has been passed, triggers the opening of the satellite valve 13 corresponding to the selected product source allowing flow of the appropriate product into the common conduit 11. iii Arrival of the pig 17 at the active pig trap 19 triggers sensor 38 closing the exhaust valve 23 and opening the main valve 15, causing product to flow to the destination to which the main valve is connected. iv Upon completion of a selected product flow volume, either by a manual operation or by programming the flow meter 16, the main valve 15 is closed triggering subsequently the introduction of pneumatic gas via valve 22 to pig trap 19 to return the pig to its rest position in pig trap 18. v Passage of the pig 17 past sensor 40 i.e. after passing the junction with connecting conduit 14, triggers the closing of the satellite valve 13, whereby remaining product being handled in the common conduit 11 is returned to its source satellite conduit via the appropriate pilot line 20 and the corresponding open pilot valve 21. The sensor 40 should be sufficiently spaced (e.g. 2m) from the first satellite connection to ensure that there is always sufficient time for the valve 13 to close before arrival of the pig, so keeping the satellite system air free. The entire product handling is air free and does not affect flow meters. The use of liquid product to push the pig means that the entire conduit volume behind the pig is full of the liquid product being conveyed. vi Finally the arrival of the pig 17 at the rest pig trap 18 triggers sensor 37 closing the pilot valve 21 and valve 22, shutting off the pneumatic gas. It will be evident that the only possible sources of contamination will be any residual product left after the operation in the common portion of the pilot line manifold and in the connection conduit between common conduit and main valve. The nominal diameter of the conduit 11 will normally be designed in line with the volume to be handled. No physical movement is required of the manifold for the conveyance of the liquid products. Essentially only two valves need to be opened and closed again on return of the pig. Contamination in a manifold of 25 satellite lines has been found in tests to be at a maximum 0.1 to 1 litre, depending upon product viscosity and the arrangement of the pilot lines and is negligible. Products tested had viscosities from 30 to 3,000 cSt (3x10 7 to 3x10 9 m 2 /s). While the illustrated embodiment is designed to be suitable for the collection of liquid products from a number of different sources, the concept of the invention can also be applied to the delivery of a product to a number of different destinations. In such a case the satellite conduits will be connected in use to the respective destinations or consumers. It will be evident that in such an arrangement the satellite conduits will require to be cleaned throughout their lengths, since different products may be flowing through them. As mentioned earlier, this is normal. The control of the operations can be effected generally as before, i.e. utilising pneumatic pressure for pig propulsion in the return direction and utilising hydraulic pressure from the single product line as the forward propulsion medium. In this case a single pilot line and pilot valve can be used to connect the dead end of pig trap 19 to the upstream (right hand) side of main valve 15 (which will in use be receiving a pumped liquid product) and the dead end of pig trap 18 arranged for receiving pneumatic gas and expelling exhaust as presently shown for trap 19. Since the downstream direction will in this case be from right to left in Figure 2 the following is a possible sequence. i Upon selection of a destination the pilot valve and exhaust valve are opened causing product to flow to pig trap 19 through the pilot line under sufficient pressure to push the pig from a rest position in trap 19 to an active position in pig trap 18. ii Passage of the pig past a sensor corresponding to sensor 39 but located downstream of the final downstream satellite connection triggers the opening of the main valve allowing flow of the product into common conduit 11. iii Arrival of the pig at pig trap 18 triggers sensor 37 to close exhaust valve and open the satellite valve 13 corresponding to the selected destination, causing product to flow to that destination. iv Upon completion of a selected product flow volume the satellite valve 13 is closed triggering subsequently the introduction of pneumatic gas to pig trap 18 to return the pig to its rest position in pig trap 19. v Passage of the pig past a sensor corresponding generally in position to sensor 40 beyond the last satellite junction and sufficiently spaced from the connection or main valve conduit 14 closes the main valve 15, whereby remaining product in common conduit 11 is returned to the source conduit on the far side of main valve 15 via the pilot line and open pilot valve. vi Finally, the arrival of the pig 17 at pig trap 19 triggers sensor 38 to close the pilot valve and shut off the pneumatic gas. It is naturally possible to utilise a manifold system of the invention at two ends of a liquid product distribution system, i.e. both for collection from a variety of sources and final delivery to a selected one of a number of destinations or consumers, the two manifold systems, which may be as separately described above, being interconnected by a common transit conduit. The transit conduit may run e.g. from a storage facility at one plant location to a consumer facility at another general location. It, like the satellite lines to different consumers, will normally require to be cleaned by a suitable pig. It will be evident that the invention provides a simple and inexpensive liquid distribution means avoiding the problems inherent in snake pits. It can be used in a great number of plants or facilities, some examples being in the loading and unloading of tank trucks, rail tanks or barges, the collection and delivery of products at tank farms, and in the filling of products via scales or meters, as well as in refineries and chemical reaction facilities.

Claims: A manifold system connectable in use for the collection of one of a variety of liquid products of differing character from a selected source, or the delivery of a said product to a selected one of a variety of destinations, comprising: a manifold (10) having a common conduit (11) connecting a plurality of satellite conduits (12) themselves connectable with respective said sources or destinations, a satellite valve (13) in each satellite conduit, a connecting conduit (14) leading from said common conduit at a position spaced from the satellite conduits, a main valve (15) in said connecting conduit, cleaning means comprising a sole pig (17) operable for freeing said common conduit of contaminants between conveyance of different said products, wherein said common conduit (11) extends from a first point (18) beyond a first satellite conduit furthermost from said connecting conduit (14) to a second point (19) beyond a junction with said connecting conduit (14), and at least one pig trap (18; 19) for parking said pig (17), characterized by a first pig trap (18) at said first point and a second pig trap (19) at said second point, wherein said pig (17) is arranged to be actuated in one direction by hydraulic pressure of a said product and in the other direction by pneumatic means and wherein both said hydraulic pressure and said pneumatic pressure are to be applied to the dead end of the respective pig trap (18; 19). A system according to claim 1 for the collection of a said product selected from a plurality of sources, characterized by a pilot manifold comprising a central pilot line (20a) connecting said first pig trap (18) to a plurality of pilot lines (20) each containing a pilot valve (21), said pilot lines (20) being respectively associated with a respective satellite conduit (12) and connected thereto at a connection point on the far side of the respective satellite valve (13) from said common conduit (11). A system according to claim 2, characterized in that said satellite conduits (12) are connected via pumps to respective product sources. A system according to claim 2 or 3 including control means (37, 38, 39, 40) arranged: upon selection of a said source to open the corresponding pilot valve (21), and to open an exhaust valve (23) in said second pig trap (19) to enable selected product to flow to said first pig trap (18) under sufficient pressure to push the pig (17) from a rest position in said trap (18) to an active position in the second pig trap (19), after passage of the pig (17) past the final satellite connection to trigger (at 39) the opening of the satellite valve (13) corresponding to the selected source to enable flow of the product into said common conduit (11), upon arrival of the pig (17) in said second pig trap (19) to close said exhaust valve (23) and open said main valve (15), enabling product to flow to a desired destination, upon completion of a selected product flow volume to close the main valve (15) and subsequently to enable the introduction of pneumatic gas (22) to said second pig trap (19) to return the pig (17) to its rest position in the first pig trap (18), following passage of the pig (17) past the junction with said connecting conduit (14) to close said satellite valve (13), whereby in use remaining product in said common conduit (11) is returned to the source conduit via the pilot line (20a, 20), upon arrival of the pig (17) in the first pig trap (18) to close said pilot valve (21) and disable entry of pneumatic gas (22). A system according to claim 1 for the delivery of a said product to a selected one of a variety of destinations, characterized by a pilot line connecting said second pig trap (19) to a connection point on the far side of the main valve (15) from the common conduit (11), said first pig trap (19) being connected to a pneumatic gas source via a gas valve (22), and to an exhaust line via an exhaust valve (23). A system according to claim 5 including control means (37, 38, 39, 40) arranged: upon selection of a said destination to open the pilot valve (21), and to open the exhaust valve in said first pig trap to enable product to flow to said second pig trap under sufficient pressure to push the pig (17) from a rest position in said trap to an active position in the first pig trap, after passage of the pig (17) past the final satellite connection to trigger the opening of the main valve (15) enabling flow of the product into said common conduit (11), upon arrival of the pig (17) in said first pig trap to close said exhaust valve and open the satellite valve (13) corresponding to the selected destination, to enable product to flow to the desired destination, upon completion of a selected product flow volume to close the satellite valve (13) and subsequently enable the introduction of pneumatic gas to said first pig trap to return the pig (17) to its rest position in the second pig trap, following passage of the pig past (17) the junction with said connecting conduit (14) to close said main valve (15), whereby in use remaining product in said common conduit (11) is returned to the source conduit via the pilot line (20), upon arrival of the pig (17) in the second pig trap to close said pilot valve (21) and disable the entry of pneumatic gas.

Inventors: LABUS WENDELIN, LABUS, WENDELIN
Applicants: NORDWIG MASCHF, MASCHINENFABRIK NORDWIG
Application year: 1995
Main classification: B08B9
IPC codes: B08B9, F17D3