Abstract:
An endless chain of elongated vehicles, each carrying a thermally insulated sealed container for liquefied gas (LNG) traveling at high speed along a guideway between loading and unloading locations. A folding mechanism turns vehicles into dense vertical side-by-side relationship for loading and unloading at low speed, similar to filling bottles by conventional bottling machines. Containers are connected to piping which recovers and returns in transit re-gasified LNG for re-liquefaction. Containers are capable of holding gas under pressure in case of extended conveyor stoppage. High vehicle speed is enhanced with magnetic levitation suspension and linear induction motor propulsion.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to design and construction of an endless chain of elongated vehicles, each carrying an elongated sealed container for liquefied gas (LNG). More specifically it relates to vehicle and container design, method of loading, unloading and transporting LNG safely and without undue re-gasification or boil-off loss in transit. Furthermore, container design and attached piping feature recovery and recycling of in transit re-gasified fluid. In general, liquefaction plants liquefy gas by cooling it to below −260° F. (−160° C.). Elongated containers are then dynamically loaded with LNG while in side-by-side upright position, similar to filling bottles by conventional bottling machines. Thereafter, containers are sealed, rotated by their vehicles into horizontal end-to-end position and rapidly transported to their destination where they are returned into the same side-by-side upright position for unloaded. Any in transit re-gasified LNG, which may occur during extended conveyor stoppage is recovered and returned for re-liquefaction by a to vehicles attached flexible endless gas return pipeline. 
       SUMMARY OF THE INVENTION 
       [0002]    The present invention provides the ability to carry LNG by a conveyor of a type having in a closed loop an endless string of elongated vehicles containing cylindrical containers traveling at relatively high rate of speed between a loading end and an unloading end, vehicles with containers being folded into dense vertical side-by-side relationship at relatively low rate of speed for loading at a loading end and for unloading at an unloading end. Containers are heat insulated and can carry contents under pressure. When in densely folded upright relationship, vehicles with containers reveal two access ports, one at the top for fluid loading and unloading, and one on the side for returned gas release. Containers are equipped with safety pressure release valves, which are connected to an attached endless flexible gas return pipe. Discharge of gas from containers is returned for re-liquefaction by a flexible gas return pipe. The box-shaped vehicles have suspension, guidance and propulsion means for high-speed travel along guideways. Vehicles are paired and coupled together by couplings so that two adjacent access ports face each other. There are two types of couplings, one with wing-like cam followers near their upper edge, which are located at the access port ends of the vehicles, and one with wing-like cam followers near their bottom edge, which are located at the opposite ends of the vehicles. Vehicles have attached on each side a row of permanent magnets magnetized in vertical direction. High-speed sections of the guideway consist of up-facing U-shaped channels having near the top of each channel leg matching rows of permanent magnets magnetized in opposite direction to those on vehicles. Suspension of vehicles thus occurs by magnetic repulsion between vehicle magnets and guideway magnets. Dual guide channels in guideway and guideway followers on the vehicles provide lateral guidance. Propulsion is by linear induction motors, the primary of which is located at intervals in the bottom center of the U-shaped guideway channel. The underside of vehicles is covered by platens, which act as linear motor secondary. The cam followers on the couplings engage stationary dual cams before and after each loading and unloading location whereby vehicles are rotated from end-to-end relationship to side-by-side relationship and back. While in side-by-side relationship, vehicles are held against, and rotate with, loading and unloading carousels, at which time containers and the flexible gas return line is accessed for loading and unloading. The flexibility of the endless gas return pipe allows it to bend with containers when they fold and unfold at loading and unloading ends. Said LNG conveyor comprising: 
         [0003]    (a) means for carrying LNG in heat insulated pressure containers; 
         [0004]    (b) means for dynamic loading and unloading containers; 
         [0005]    (c) means for in transit re-gasified LNG to be recovered for re-liquefaction; 
         [0006]    (d) means for guiding and propelling containers along guideways. 
         [0007]    The present invention is intended to enable transportation overland of LNG in large quantities, similar to what is already commonly done by ship at sea. The advantage of liquefaction is that gas volume is thereby reduced by a ratio of about 620 to one. While LNG ships take many days for a single delivery, they have on board refrigeration machines to prevent re-gasification of their cargo. Re-gasification expands LNG back to its original volume, except when it is confined in pressure containers. The present invention has no refrigeration machines traveling with its containers. Instead it relies on delivering LNG at high rate of speed, thereby leaving very little time for temperature increase and LNG re-gasification in transit. To enable high speed, means of suspension consist of permanent magnets in repulsion, and means for propulsion consist of linear induction motors. 
         [0008]    Large quantities of stranded natural gas in remote regions could be brought as LNG to market with this invention, for example, from the North Slope of Alaska for a distance of 800 miles (1,300 Km) to a shipping port in the south of Alaska. With a line speed of 200 miles/hour (320 Km/hour), containers would be exposed for four hours to LNG re-gasification inducing surroundings, which with pre-cooling of LNG to lower than re-gasification temperature and with good insulation would keep heat intrusion and re-gasification to a minimum. However, the present invention provides that any emitted gas due to re-gasification and excessive container pressure would be recovered and returned for re-liquefaction by the endless flexible gas return pipe to which all containers are connected. No gas would be released to the outside. 
         [0009]    For a shorter application, the present invention could also be used as an LNG Land Bridge across Panama similar to what already exists there for crude oil. Many new LNG ships are now also too large to fit through the Panama Canal. LNG re-gasification while in transit may also be reduced or even totally avoided by (1) pre-cooling containers before filling, (2) filling containers only partially and (3) replacing long conveyors with shorter ones interspaced with liquefaction booster plants. 
     
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0010]      FIG. 1  shows a plan view of an LNG Land Bridge. 
           [0011]      FIG. 2 . shows a longitudinal section of a vehicle with LNG container. 
           [0012]      FIG. 3  shows a cross-section of a vehicle with LNG container and linear motor. 
           [0013]      FIG. 4  shows a side view of a vehicle with connecting links, cam followers and linear motor. 
           [0014]      FIG. 5  shows vehicles being folded and unfolded by cams. 
           [0015]      FIG. 6  shows a partial cross-section through a loading carousel. 
           [0016]      FIG. 7  shows a partial cross-section through an unloading carousel. 
           [0017]      FIG. 8  shows prior art of an elevated view of an LNG Land Bridge construction by helicopter. 
           [0018]      FIG. 9  shows prior art of a triangular truss support structure for an LNG Land Bridge. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]      FIG. 1  shows a plan view of a typical LNG Land Bridge  1 . Being temporarily attached to carousel  2 , an endless succession of container-carrying vehicles progress slowly through loading end  3  in dense upright side-by-side relationship being filled with LNG through ports at their tops. Assuming carousel  2  is rotating clockwise in  FIG. 1 , containers are rotated in a vertical plane in deceleration section  4  from a horizontal end-to-end relationship to an upright side-by-side relationship. The reverse vertical rotation occurs in acceleration section  5 . Thereafter, vehicles carrying LNG filled containers are propelled at high speed along guideway  6  and empty returns are propelled at high speed along guideway  7 . Arriving for discharge, vehicles with filled containers are again rotated in a vertical plane into dense upright side-by-side relationship in deceleration section  8 . Vehicles are unloaded through ports at their tops, while being temporarily attached to carousel  9 , at unloading end  10 . Thereafter, vehicles are again unfolded in acceleration section  11 . 
         [0020]      FIG. 2  shows a longitudinal section of vehicle  12  exposing the therein-located LNG container  13  embedded in thermal insulation  14 . Container  13  has an internal filling and emptying tube  15  with an access port  16  at the top for loading and unloading of LNG. Tube  17  connects container  13  to the inlet side of pressure release valve  18 . Tube  19  connects the outlet side of pressure release valve  18  to endless flexible gas return pipe  20 . The flexibility of gas return pipe  20  allows it to bend with vehicles  12  as they fold and unfold during speed change. Gas return pipe  20  has an access port  21  at a uniform location on each vehicle  12  for unloading returned gas. 
         [0021]      FIG. 3  shows a cross-section of high-speed guideway sections  6  and  7 . Vehicle  12  has in the center on each side from end-to-end wing-like lateral extensions  22 . Imbedded in lateral extensions  22  flush with their underside surfaces are rows of permanent magnets  23  magnetized in vertical direction. Directly underneath magnets  23 , in close proximity and magnetized in opposite direction to those on vehicles  12 , are matching permanent magnets  24  attached to the tops of the sides of open at the top guideway channel  25 . Magnets  23  on vehicle  12  and magnets  24  in guideway channel  25  are magnetically repelling each other vertically and thereby cause magnetic levitation of vehicle  12 . Attached at the bottom corners of vehicle  12  and facing outwards are periodically adjustable self-lubricating plastic sliders  26 . Imbedded in the sides of guideway channels  25 , opposite sliders  26  and facing inwards, are recessed guide channels  27 . Sliders  26  are in sliding engagement with guide channels  27 , thereby providing lateral guidance. Located centrally underneath vehicle  12  and attached at intervals to guideway channel  25  is primary winding  28  of linear motor  29 . Attached to the underside of vehicle  12  and held in close proximity above linear motor primary winding  28  is linear motor secondary  30  in the form of a platen extending the full length of vehicle  12 . 
         [0022]      FIG. 4  shows a side view of vehicles  12  in end-to-end alignment connected to each other by couplings  31  and  32  with linear induction motor  29  underneath. Coupling  31  has on each side laterally extending wing-like cam followers  33  at its top edge, alternating with coupling  32 , which has laterally extending wing-like cam followers  34  at its bottom edge. Pins  35  connect couplings  31  and  32  to vehicle  12 , whereby adjacent vehicles  12  can be folded into dense side-by-side relationship and back to end-to-end relationship. Containers  13  are oriented in alternating directions in vehicles  12  so that two adjacent access ports  16  are facing each other at coupling  31  and their closed ends facing each other at coupling  32 . 
         [0023]      FIG. 5  shows an illustration of how diverging and converging cams cause the continuous folding and unfolding of vehicles  12  in acceleration sections  5  and  11  and in deceleration sections  4  and  8 . Assuming direction of motion in  FIG. 5  from left to right, on arrival in end-to-end relationship wing-like cam followers  33  engage and follow dual upper cams  36 , and wing-like cam followers  34  engage and follow dual lower cams  37 . Cams  36  and  37  end at the point where vehicles  12  are densely folded against each other, which is also the point where loading or unloading starts. 
         [0024]      FIG. 6  shows the right half of a cross-section of carousel  2  depicting the loading operation as occurring at loading end  3 . LNG is flowing through stationary intake pipe  38  to, and thereafter downward, along the center of rotation  39  of carousel  2 . From there it flows on through swivel coupling  40  into header  41  which is attached to, and rotates with, carousel  2  at an elevated location. Down-sloping pipes  42  connect header  41  with loading nozzles  43 , one for each container  13 . Concurrently with the LNG loading operation, gas from gas return pipe  20  is released through temporary connection to access port  21  into pipe  44  and from there to the center of rotation  39  and through swivel coupling  45  into stationary discharge pipe  46  for re-liquefaction. 
         [0025]      FIG. 7  shows the right half of a cross-section of carousel  9  depicting the unloading operation as occurring at unloading end  10 . LNG arrives under pressure in containers  13 . Unloading nozzles  47  make contact with access port  16  at each container  13 . Induced pressure differential forces LNG out of containers  13  through internal filling and emptying tube  15 . Down-sloping pipes  48  transmit the LNG to header  49  at the center of rotation  50 , and from there through swivel coupling  51  to stationary discharge pipe  52 , which is connected to the suction sides of pumps which forward the LNG to storage and shipping facilities. Concurrently with the LNG unloading operation, gas from gas return pipe  20 , if present, is released through temporary connection to access port  21  into pipe  53  and from there to the center of rotation  50  and on through swivel coupling  55  into stationary discharge pipe  56  for re-liquefaction. 
         [0026]      FIG. 8  shows prior art of construction by helicopter of an elevated guideway support structure required for an LNG Land Bridge. It has a continuous cable suspended triangular truss, which is needed to hold the LNG Land Bridge guideways in smooth alignment in straight-aways, vertical curves, banked horizontal curves and transitions in between, enabling the passing at high speed over rugged terrain and high mountains. 
         [0027]      FIG. 9  shows prior art of details of an elevated triangular truss support structure with a loaded vehicle guideway and empty return vehicle guideway on top. 
         [0000]    The best mode of carrying out the present invention is as follows:
       1. Elect capacity, design physical components for the elected capacity and perform full size tests.   2. Erect an elevated triangular truss support structure along the route and attach the LNG Land Bridge to its top.   3. Constructs LNG supply facilities at the loading end of the LNG Land Bridge,   4. Construct LNG shipping facilities at the unloading end of the LNG Land Bridge.