Abstract: Overflash within a withdrawal zone of a complex fractionating column is monitored to provide a control characteristic related to the efficiency of the fractionation column, and associated processes linked to the column. To accurately monitor the overflash, notched weir means including an upright wall means, is positioned at the intersection of the withdrawal tray and the downcomers connecting the former with a lower, adjacent fractionating tray. Differential pressure measuring means is also provided with sensing means in the vicinity of the notched weir means. The differential pressure measuring means produces a signal characteristic of said overflash. A complex controller means, external of the column, generates correction operators in response to said signal. Respective control means regulate column feed and withdrawal streams in response to said correction operators and thus maintain a pre-selected material balance within the column.

Abstract: 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.

Abstract: A scale removal method for use in saline water desalting apparatus characterized in that, during the time the desalting operation is being performed, an acid is added to the saline water for short periods at predetermined time intervals in the salt water passages for condensation, heating and heat recovery.

Abstract: 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.