| 摘要 |
In a fractional distillation process in which first (light key) and second (heavy key) components contained in a feed stream are separated with the major portion of the light key component being removed in an overhead product stream and the major portion of the heavy key component being removed in a bottoms product stream, a signal which is responsive to the concentration of the light key component in the bottoms product stream is summed with a signal which is responsive to the concentration of the heavy key component in the overhead product stream to derive a signal which is utilized to manipulate the flow rate of the external reflux (sigma control). Also, the difference between a signal which is responsive to the concentration of the light key component in the bottoms product stream and a signal which is responsive to the concentration of the heavy key component in the overhead product stream is utilized to control the flow rate of the bottoms product stream (delta control). The sigma-delta control results in decoupling of the overhead product composition control and bottoms product composition control, improved recovery from disturbances and increased stability of the process.
|
