Patent ID: 7404301

Claim:
A method for liquefying a natural gas stream in an LNG facility, said method comprising: (a) cooling at least a portion of said natural gas stream in a first closed-loop refrigeration cycle via indirect heat exchange with a first refrigerant to thereby provide a cooled natural gas stream; (b) introducing at least a portion of an initial LNG produced in said LNG facility into a first LNG tank, wherein said initial LNG comprises at least a portion of said cooled natural gas stream, wherein said initial LNG has a higher heating value (HHV) less than 1,150 BTU/SCF; (c) removing at least a portion of said initial LNG from said first LNG tank; (d) cooling a spiking fluid having an HHV greater than 1,500 BTU/SCF in a second refrigeration cycle via indirect heat exchange with a second refrigerant to thereby provide a cooled spiking fluid, wherein said second refrigerant has a different composition than said first refrigerant; (e) combining at least a portion of said cooled spiking fluid with at least a portion of the removed initial LNG stream to thereby form a spiked LNG stream; and (f) introducing at least a portion of the spiked LNG stream into a second LNG tank.