Portable system and method for transferring liquefied gas

Abstract

A portable self-contained system for transferring liquefied gas, such as liquid petroleum gas or anhydrous ammonia, from a source tank (e.g., a railcar) to a receiving tank (e.g., a truck cargo tank), includes a portable platform providing transfer equipment such as a motor powered compressor, operating controls, transfer lines as well as valves and connectors to manage and direct the flow of fluid, and emergency controls such as shut off valves and pull away connectors for safety. A grounding system, safety shower and fire suppression system are also provided. A method for transferring liquefied gas from a source tank to a receiving tank using the portable self-contained transfer system includes steps of positioning the transfer system; establishing liquefied gas line and vapor line connections; pulling vapor from the receiving tank, compressing it and forcing it into the source tank, thereby enabling the pressurized vapor to force liquid from the source tank through a vapor line into the source tank; reconfiguring valves, lines and connections to recover residual liquid and vapors from the nearly emptied source tank; evacuating liquid from the liquid lines; and disconnecting the system.

Having thus described the present invention, what is claimed as new and desired to be secured by Letters Patent is as follows:  
     
         1 . A system for transferring liquefied gas from a source tank to a receiving tank, said system including: 
 a portable platform and    liquefied gas transfer means.    
     
     
         2 . A system according to claim I further including a plurality of rotatable wheels functionally connected to the portable platform to facilitate transportation.  
     
     
         3 . A system according to  claim 2  further comprising means for towing the portable platform.  
     
     
         4 . A system according to  claim 3  wherein the means for towing includes a tow bar, said tow bar having a first end and a second end, the first end being functionally connected to the portable platform to facilitate towing, the second end having means for releasable attachment to a vehicle for towing.  
     
     
         5 . A system according to  claim 1  further including an elevated platform attached to the portable platform, said elevated platform having a height above ground level.  
     
     
         6 . A system according to  claim 5  further including means for accessing the elevated platform.  
     
     
         7 . A system according to  claim 6 , wherein the means for accessing the elevated platform includes climbing means from the group consisting of a stairway and a ladder.  
     
     
         8 . A system according to  claim 5  further including a walkway for accessing the top of a nearby tank having a height that is the same as or close to the height of the elevated platform.  
     
     
         9 . A system according to  claim 8  further including hinged attachment means for attaching the walkway to the elevated platform.  
     
     
         10 . A system according to  claim 9  wherein the walkway further includes means for folding the walkway to facilitate storage.  
     
     
         11 . A system according to  claim 8  wherein the walkway is comprised of a material that is not likely to generate sparks upon contacting the nearby tank.  
     
     
         12 . A system according to  claim 11  wherein the walkway is comprised of aluminum.  
     
     
         13 . A system according to  claim 5  further including an elevated vapor hose fluidly connected to the liquefied gas transfer means, an elevated liquid hose, a first boom and a second boom, a plurality of releasable boom attachment means for releasably attaching the elevated vapor and liquid hoses to the first and second booms, the first boom and second boom being functionally attached to the elevated platform, the elevated vapor hose being releasably attached to the first boom using a releasable boom attachment means, and the elevated liquid hose being releasably attached to the second boom using a releasable boom attachment means.  
     
     
         14 . A system according to  claim 13  wherein the first boom is pivotable about a first vertical axis to facilitate positioning of the boom, and the second boom is pivotable about a second vertical axis to facilitate positioning of the boom.  
     
     
         15 . A system according to  claim 13  further including a first pullaway connector functionally connected to the elevated vapor hose and a second pullaway connector functionally connected to the elevated liquid hose.  
     
     
         16 . A system according to  claim 13  further including a first emergency shutoff valve functionally connected to the elevated vapor hose and a second emergency shutoff valve functionally connected to the elevated liquid hose.  
     
     
         17 . A system according to  claim 16  further including a platform level vapor hose fluidly connected to the liquefied gas transfer means, and a platform level liquid hose fluidly connected to the elevated liquid hose.  
     
     
         18 . A system according to  claim 17  further including a third pullaway connector functionally connected to the platform level vapor hose and fourth pullaway connector functionally connected to the platform level liquid hose.  
     
     
         19 . A system according to  claim 18  further including a third emergency shutoff valve functionally connected to the platform level vapor hose and a fourth emergency shutoff valve functionally connected to the platform level liquid hose.  
     
     
         20 . A system according to  claim 19  further including an emergency shutoff means for shutting off the first, second, third and fourth emergency shutoff valves.  
     
     
         21 . A system according to  claim 20  wherein the emergency shutoff means includes an emergency shutoff switch located at or near the platform, an emergency shutoff switch located at or near the elevated platform and an emergency shutoff switch located a determined distance from the platform.  
     
     
         22 . A system according to  claim 1  further including a grounding means for grounding the source and receiving tanks.  
     
     
         23 . A system according to  claim 22  wherein the grounding means includes a portable grounding system.  
     
     
         24 . A system according to  claim 1  further including a safety shower.  
     
     
         25 . A system according to  claim 24  wherein the safety shower is a portable safety shower.  
     
     
         26 . A system according to  claim 1  further including fire suppression means.  
     
     
         27 . A system according to  claim 26  wherein the fire suppression means includes an ABC class fire extinguisher releasably attached to the system.  
     
     
         28 . A system according to  claim 1  wherein the liquefied gas transfer means includes a compressor having an outlet and an inlet.  
     
     
         29 . A system according to  claim 28  further including a control valve fluidly connected to the inlet of the compressor and to the outlet of the compressor, said control valve having a first line connection and a second line connection each of which may be used for connecting a line to the control valve, said control valve also having a first setting that fluidly connects the first line connection to the inlet of the compressor and the second line connection to the outlet of the compressor, and a second setting that fluidly connects the second line connection to the inlet of the compressor and the first line connection to the outlet of the compressor.  
     
     
         30 . A system according to  claim 29  further including: 
 a first vapor hose having a first end and a second end, the first end being fluidly connected to the first line connection of the control valve,  
 a first liquid hose having a first end and a second end,  
 a second vapor hose having a first end and a second end, the first end being fluidly connected to the second line connection of the control valve, and  
 a second liquid hose having a first end and a second end.  
 
     
     
         31 . A system according to  claim 30  further including: 
 a first pullaway connector functionally connected to the first vapor hose and a second pullaway connector functionally connected to the first liquid hose,  
 a first emergency shutoff valve functionally connected to the first vapor hose and a second emergency shutoff valve functionally connected to the first liquid hose,  
 a third pullaway connector functionally connected to the second vapor hose and fourth pullaway connector functionally connected to the second liquid hose, and  
 a third emergency shutoff valve functionally connected to the second vapor hose and a fourth emergency shutoff valve functionally connected to the second liquid hose.  
 
     
     
         32 . A system according to  claim 31  further including: 
 an emergency shutoff means for shutting off the first, second, third and fourth emergency shutoff valves, wherein the emergency shutoff means includes an emergency shutoff switch located at or near the platform and an emergency shutoff switch located a determined distance from the platform.  
 
     
     
         33 . A system according to  claim 32  further including a portable grounding means for grounding the source and receiving tanks.  
     
     
         34 . A system according to  claim 33  further including a portable safety shower.  
     
     
         35 . A system according to  claim 34  further including a fire suppression means, wherein the fire suppression means includes an ABC class fire extinguisher releasably attached to the system.  
     
     
         36 . A system according to  claim 35  further including a means for towing the portable platform, the means for towing including a tow bar, said tow bar having a first end and a second end, the first end being functionally connected to the portable platform to facilitate towing, the second end having means for releasable attachment to a vehicle for towing.  
     
     
         38 . A method for transferring liquefied gas from a source tank having liquefied gas and vapors to a receiving tank having vapors using a system according to  claim 1 , said method including steps of 
 positioning the system to perform the transfer,    fluidly connecting the liquefied gas transfer means to the receiving tank to enable the liquid transfer means to draw vapors from the receiving tank,    fluidly connecting the liquefied gas transfer means to the source tank to enable the liquid transfer means to pump compressed vapors drawn from the receiving tank into the source tank, thereby increasing the vapor pressure in the source tank,    fluidly connecting the source tank to the receiving tank to enable liquefied gas to flow from the source tank to the receiving tank,    operating the liquefied gas transfer means to draw vapors from the receiving tank through the liquefied gas transfer means and into the source tank, thereby increasing the vapor pressure in the source tank and forcing liquefied gas from the source tank into the receiving tank.    
     
     
         39 . A method according to  claim 38  further including steps of 
 disabling the fluid connections established according to  claim 35 , thereby preventing liquefied gas from flowing from the source tank into the receiving tank, and preventing vapors from being drawn from the receiving tank and pumped into the source tank,  
 fluidly connecting the liquefied gas transfer means to the source tank to enable the liquid transfer means to draw vapors from the receiving tank,  
 fluidly connecting the liquefied gas transfer means to the receiving tank to enable the liquid transfer means to pump compressed vapors drawn from the source tank into liquefied gas that was forced into the receiving tank according to  claim 38 , and  
 operating the liquefied gas transfer means to draw vapors from the source tank through the liquefied gas transfer means and into the liquefied gas contained in the receiving tank, thereby decreasing vapor pressure in the source tank and promoting evaporation of liquefied gas in the source tank, and enabling all or some of said compressed vapors to cool and condense in the liquefied gas of the receiving tank.  
 
     
     
         40 . A method for transferring liquefied gas and vapors from a source tank having liquefied gas and vapors to a receiving tank having vapors using a system according to  claim 30 , said method including steps of 
 positioning the system to perform the transfer,    fluidly connecting the second end of the first vapor hose to the source tank,    fluidly connecting the first end of the first liquid hose to the first end of the second liquid hose,    fluidly connecting the second end of the first liquid hose to the source tank,    fluidly connecting the second end of the second vapor hose to the receiving tank,    fluidly connecting the second end of the second liquid hose to the receiving tank,    setting the control valve such that the first line connection, which is connected to the first end of the first vapor hose, is fluidly connected to the outlet of the compressor and the second line connection, which is connected to the first end of the second vapor hose, is fluidly connected to the inlet of the compressor, and    operating the liquefied gas transfer means to draw vapors from the receiving tank, through the second vapor hose, into the liquefied gas transfer means, through the first vapor hose and then into the source tank, thereby increasing the source tank's vapor pressure to force liquefied gas from the source tank, through the first liquid hose, into the second liquid hose, and then into the receiving tank.    
     
     
         41 . A method according to  claim 40  further comprising steps of 
 disabling at least one of the following connections: 
 the connection between the first end of the first liquid hose and the first end of the second liquid hose,  
 the connection between the second end of the first liquid hose and the source tank, and  
 the connection between the second end of the second liquid hose and the receiving tank, and  
 
 setting the control valve such that the first line connection, which is connected to the first end of the first vapor hose, is fluidly connected to the inlet of the compressor and the second line connection, which is connected to the first end of the second vapor hose, is fluidly connected to the outlet of the compressor, and  
 operating the liquefied gas transfer means to draw vapors from the source tank, through the first vapor hose, into the liquefied gas transfer means, through the second vapor hose and into the liquefied gas contained in the receiving tank, thereby decreasing vapor pressure in the source tank and promoting evaporation of liquefied gas in the source tank, and enabling all or some of said compressed vapors to cool and condense in the liquefied gas of the receiving tank.  
 
     
     
         42 . A method according to  claim 41  further comprising steps of 
 evacuating liquefied gas from the first liquefied gas hose,  
 and evacuating liquefied gas from the second liquefied gas hose.  
 
     
     
         43 . A method for transferring liquefied gas and vapors from a source tank to a receiving tank using a system according to  claim 1 , said method including steps of 
 positioning the system to perform the transfer,    establishing a vapor line connection from the source tank to the liquefied gas transfer means,    establishing a vapor line connection from the receiving tank to the liquefied gas transfer means,    establishing a liquefied gas line connection from the source tank to the receiving tank, 
 operating the liquefied gas transfer means to draw vapors from the receiving tank, through vapor line connection from the receiving tank to the liquefied gas transfer means, through the vapor line connection from the source tank and then into the source tank, thereby increasing the source tank's vapor pressure to force liquefied gas from the source tank, through the liquefied gas line connection from the source tank to the receiving tank, into the receiving tank.  
   
     
     
         44 . A method according to  claim 43  further comprising the step of recovering vapors from the source tank into the liquefied gas transferred into the receiving tank.  
     
     
         45 . A method according to  claim 44  further comprising the step of evacuating liquefied gas from the liquefied gas line connection from the source tank to the receiving tank.