Method for Handling Bituminous Crude Oil in Tank Cars

Abstract

Bituminous heavy crude oil is kept at elevated temperatures in order to flow and may be transported in one direction, and light hydrocarbons typically comprising of mixtures of components of which the majority will have molecular chain lengths of 2 to 12 carbon atoms, such as Liquefied Petroleum Gas (LPG), Natural Gas Liquids (NGL), light naphtha, natural gasoline and natural gas condensates may be transported in the opposite direction.

What is claimed is: 
     
         1 . A method for changing a rail tank car from transporting heated bituminous crude oil to transporting light hydrocarbons comprising:
 transporting the bituminous crude oil at a temperature of 70° C. or higher under its own vapor pressure; and   discharging bituminous crude oil from a rail car at a destination without reheating using light hydrocarbon vapor.   
     
     
         2 . The method of  claim 1  including using the presence of near vacuum in the rail tank car's vapor space as a safety check against the potential ingress of air during transit before the introduction of light hydrocarbons, using light hydrocarbon vapors under pressure to discharge the bituminous crude oil from the rail tank car, and refilling the rail tank car with light hydrocarbons to be transported back to the location where the bituminous crude oil was loaded. 
     
     
         3 . The method of  claim 2  including controlling the introduction of light hydrocarbon liquids such that the vapor generated by the boil off when these liquids come into contact with the rail tank car and a small quantity of remaining bitumen liquids does not cause the pressure in the rail tank car to exceed its design pressure, and the vaporization of the light hydrocarbons is used to cool down the rail tank car and its contents. 
     
     
         4 . The method of  claim 3  including condensing the boiled-off light hydrocarbon vapors and the vapors displaced when filling the rail tank car with light hydrocarbons by reversing the flow in the system that delivered the light hydrocarbon vapors for the discharge of the bituminous crude oil and leading the vapors to a condenser to recover liquids. 
     
     
         5 . The method of  claim 1  including filling the rail tank car with liquid light hydrocarbons at a fill rate of greater than 100 cubic meters per hour. 
     
     
         6 . The method of  claim 1  using the presence of overpressure in the rail tank car's vapor space as a safety check against the potential ingress of air during transit before the introduction of light hydrocarbons, and venting off the excess nitrogen pressure upon arrival of the rail tank cars at the destination. 
     
     
         7 . The method of  claim 6  including venting incondensable inert gases containing the nitrogen introduced in the vapor space at the loading point in a controlled manner, using a vapor recovery unit or vapor destruction unit to remove any hydrocarbons contained in the incondensable inert gases. 
     
     
         8 . The method of  claim 1  including providing the rail car with external coils that allow the transfer of heat from a suitable heating medium to reheat the bitumen, said coils acting as external stiffeners to enable the rail tank car to withstand full internal vacuum. 
     
     
         9 . A method comprising:
 receiving a tank car with bituminous crude oil at a temperature of at least 70° C.;   discharging the bituminous crude oil at a temperature of at least 30° C. using light hydrocarbon vapors; and   refilling the rail tank car with light hydrocarbons.   
     
     
         10 . The method of  claim 9  including using the presence of near vacuum in the rail tank car's vapor space as a safety check against the potential ingress of air during transit before the introduction of light hydrocarbons, using light hydrocarbon vapors under pressure to discharge the bituminous crude oil from the rail tank car, and refilling the rail tank car with light hydrocarbons to be transported back to the location where the bituminous crude oil was loaded. 
     
     
         11 . The method of  claim 10  including controlling the introduction of light hydrocarbon liquids such that the vapor generated by the boil off when these liquids come into contact with the rail tank car and a small quantity of remaining bitumen liquids does not cause the pressure in the rail tank car to exceed its design pressure, and the vaporization of the light hydrocarbons is used to cool down the rail tank car and its contents. 
     
     
         12 . The method of  claim 11  including condensing the boiled-off light hydrocarbon vapors and the vapors displaced when filling the rail tank car with light hydrocarbons by reversing the flow in the system that delivered the light hydrocarbon vapors for the discharge of the bituminous crude oil and leading the vapors to a condenser to recover liquids. 
     
     
         13 . The method of  claim 9  including filling the rail tank car with liquid light hydrocarbons at a fill rate of greater than 100 cubic meters per hour once the rail tank car and its contents have been cooled down sufficiently to allow rapid filling. 
     
     
         14 . The method of  claim 9  using the presence of overpressure in the rail tank car's vapor space as a safety check against the potential ingress of air during transit before the introduction of light hydrocarbons, and venting off the excess nitrogen pressure upon arrival of the rail tank cars at the destination. 
     
     
         15 . The method of  claim 14  including venting incondensable inert gases containing the nitrogen introduced in the vapor space at the loading point in a controlled manner, using a vapor recovery unit or vapor destruction unit to remove any hydrocarbons contained in the incondensable gases. 
     
     
         16 . A rail car terminal comprising:
 a condensate vaporizer to vaporize liquid light hydrocarbons and to supply the hydrocarbons to a rail car;   a condenser to condense light hydrocarbon vapors from said car; and   a pressure control system to control the pressure of condensate vapors.   
     
     
         17 . The terminal of  claim 16  said vaporizer to fill the car at a rate greater than 100 cubic meters per hour. 
     
     
         18 . The terminal of  claim 16  including a vapor recovery unit or vapor destruction unit to remove hydrocarbons contained in condensable inert gases. 
     
     
         19 . The terminal of  claim 16  to discharge bituminous crude oil from said car using light hydrocarbon vapors. 
     
     
         20 . The terminal of  claim 19  to discharge bituminous crude oil from said car at a temperature of at least 30° C. 
     
     
         21 . A rail car comprising:
 a shell;   external heating coils extending around said shell to heat the contents of said shell; and   said coils acting as stiffeners to enable said shell to withstand full internal vacuum.