| 摘要 |
Method and apparatus are disclosed for the automatic adjustment of the fractionation column pressure in a fractionator system which employs total condensation of overhead vapor and a liquid full reflux accumulator to thus float the column pressure above minimum column pressure. The set point of a condensder fan pitch controller, which manipulates the blade pitch of the condenser fan, is automatically adjusted in response to a desired offset of condensate subcooling from the overhead bubble point temperature which is repeatedly automatically calculated in response to analysis of the overhead product composition and pressure. The set point of a pressure controller, which manipulates the overhead product control valve to adjust column pressure, is automatically adjusted in response to a fan pitch signal from the condenser fan pitch controller and a desired fan pitch set point. Appropriate limits and overrides are also disclosed to prevent sudden changes in column pressure which might upset system operation.
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