Pressure responsive fractionation control
AssigneePhillips Petroleum Company
InventorsDexter E. Smith, Russel A. Buss, William S. Stewart
Life of this patent
Estimating the term…
Abstract
In a fractionation system in which pressure fluctuations within the fractionation vessel can result in alteration of the fractionator product composition, fractionation column pressure is monitored and converted to a temperature requirement signal representative of the temperature required within a preselected portion of the fractionation column in order to provide the desired product constituent distribution. The heat input to the fractionation column is controlled in response to the temperature requirement signal, corrected as necessary by actual analysis of the product. In a preferred embodiment, control of a demethanizer column in a cryogenic natural gas liquids separation process can be practiced advantageously.
Claims21
Apparatus comprising:
- fractionation column means for receiving at least one feed material stream and delivering an overhead product stream from the top portion thereof and a bottom product stream from the bottom portion thereof;
- heating means for providing heat to said bottom portion of said fractionation column means;
- temperature transducer means for sensing a column bottom temperature within said fractionation column means adjacent the bottom thereof and delivering a bottom temperature signal representative of the thus sensed temperature;
- temperature controller means for controlling the amount of heat flow delivered to said bottom portion of said fractionation column means by said heating means in response to a comparison of said bottom temperature signal with a bottom temperature set point signal;
- pressure transducer means for sensing the pressure at a preselected location within said fractionation column means and delivering a column pressure signal representative of the thus sensed pressure;
- signal conversion means for accepting said column pressure signal and delivering in response thereto a temperature requirement signal representative of the value of said column bottom temperature required to provide a preselected value of a constituent ratio in said bottom product stream at the column pressure represented by said column pressure signal;
- analyzer means for analyzing said bottom product stream and delivering an analysis signal representative of the analyzed value of said constituent ratio within said bottom product stream;
- analysis controller means for delivering, in response to comparison of said analysis signal with a constituent ratio set point signal, a temperature requirement adjustment signal representative of the adjustment of said temperature requirement signal necessary to compensate for the difference between said preselected value of said constituent ratio and the analyzed value of said constituent ratio;
- and
- correction means for applying said temperature requirement adjustment signal to said temperature requirement signal to produce said bottom temperature set point signal.
A method for operating a fractionation column, said method comprising:
- providing at least one feed material stream to said fractionation column;
- recovering an overhead product stream from the top portion of said fractionation column;
- recovering a bottom product stream from the bottom portion of said fractionation column;
- generating a column bottom temperature signal representative of the temperature within said fractionation column adjacent the bottom thereof;
- generating a column pressure signal representative of the pressure at a preselected location within said fractionation column;
- generating an analysis signal representative of the composition of said bottom product stream;
- generating, in response to said column pressure signal and said analysis signal, a temperature set point signal representative of the fractionation column bottom temperature required to provide a preselected bottom product composition;
- and
- controlling the flow of heat to the bottom portion of said fractionation column in response to a comparison of said bottom temperature signal and said temperature set point signal to provide a fractionation column bottom temperature represented by said temperature set point signal.
Dependencies are inferred from the claim text.