| 摘要 |
A natural gas liquefaction train (100, 100a-100n) includes a nitrogen cooling loop. A controller (208a-208n, 300) is provided for controlling one or more controlled variables by adjusting one or more manipulated variables. The one or more manipulated variables may include a nitrogen flow associated with the nitrogen cooling loop in the natural gas liquefaction train. The controller could adjust the nitrogen flow by adjusting operation of a compressor (178) associated with the nitrogen cooling loop. The one or more controlled variables may include a rundown temperature of liquefied natural gas exiting the nitrogen loop and/or a calorific or heating value of the liquefied natural gas exiting the nitrogen loop. A second controller (206a-206n) could control other aspects of the natural gas liquefaction train, such as by controlling a mass flow rate of a feed gas in the natural gas liquefaction train. |
