Texaco Inc.

Glenn A Senters

Charles W Harrison

Herbert J Pitman

A method of dewaxing oil which employs the application of reversing electromotive force to the oil while it is being chilled, in order to prevent adherence of the wax crystals. An apparatus combination for dewaxing oil. It includes an elongated container for chilling a body of waxy oil as it flows through. The container acts as one of a pair of electrodes for applying a reversable electromotive force to the oil in order to prevent any adherence. The wax may be recovered by separation following the application of the electrical force.

Apparatus for oil dewaxing

The reboiler temperature of a depropanizer tower is controlled as the function of the propane content of the feed to the depropanizer tower and of the gasoline provided by the tower in accordance with a control signal. The Reid Vapor Pressure of crude oil feeding a flash tower is determined from the propane content of the depropanizer feed while the Reid Vapor Pressure of the gasoline is determined from the gasoline propane content. A control unit includes a network which determines a change in the Reid Vapor Pressure as the quality of the feed crude oil to the flash tower changes. When the change in the Reid Vapor Pressure exceeds a predetermined limit, the network provides a feed forward signal corresponding to a desired temperature associated with the new Reid Vapor pressure. The feed forward desired temperature signal is determined in accordance with the equations hereinafter disclosed. The feed forward desired temperature signal is supplied to a set point signal circuit which implements the feed forward desired temperature signal, after the elapse of a first predetermined time interval to account for the delay time for the change of feed crude oil, to affect the quality of the product from the depropanizer tower. A feedback desired temperature signal is developed from the equations. The set point signal circuit provides the feedback desired temperature signal as the control signal whenever it is not providing the feed forward desired temperature signal as the control signal.

Controlling the temperature of a depropanizer tower by chromatographic

The temperature of light straight run gasoline from a depropanizer tower is controlled as the function of the Reid Vapor Pressure change of a crude oil feeding a flash tower which provides an overhead product to the depropanizer tower and flashed crude oil to an atmospheric tower. The Reid Vapor Pressure is determined from the overhead product, the flashed crude, the pressure of the vapor in the flash tower and the temperature of liquid in the flash tower. A control unit includes a network which determines a change in the Reid Vapor Pressure as the quality of the feed crude oil to the flash tower changes. The network determines the change in the Reid Vapor Pressure and when the change exceeds a limit, provides a feed forward signal corresponding to a desired temperature associated with the new Reid Vapor Pressure. The desired temperature signal is determined in accordance with the equations hereinafter disclosed. The desired temperature signal is supplied to a time select circuit which will not implement the desired temperature signal until after the elapse of a predetermined time interval to account for the delay time for the change of feed crude oil to effect the quality of the feed to the depropanizer tower so that the temperature control may be implemented at the proper time.

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Beaumont, TX, United States of America

Glenn A Senters