| 摘要 |
In a cryogenic condensation scheme used for benzene removal in a process for liquefying natural gas, two series connected separation columns (10, 12) are provided with a feedstream (44) precooled in a heat exchanger (16) to a temperature that will at least condense the benzene component. In the first column (50), benzene is absorbed and vapor/liquid is separated with the liquid passed to the second column (60). The second column (60) provides an overhead vapor stream (68) conserved for processing to LNG, and a bottom stream comprising NGL. The cooling for condensation of gaseous feed in the heat exchanger is controlled by automatically manipulating bypass flow (38) around the heat exchanger responsive to measured vapor flow (80) from the second separation column. Accordingly, the amount of liquid (36) condensed is responsive to the flow rate of vapor withdrawn overhead from the second separation column.
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